Knowledge of water quality in aquaculture ponds in Ghana is limited due to lack of qualitative and quantitative field data. We conducted detailed field measurements to assess the effect of hydrographic and production factors on water quality. Ponds cultured with Nile tilapia Oreochromis niloticus, and African catfish Clarias gariepinus, were selected for the study. Eleven fish ponds with stock ranging between 7-21 days were randomly selected and sampled at monthly intervals for five months, with the aim of capturing water quality patterns through a full production cycle. Seventeen parameters were measured and analyzed using Partial Least Squares (PLS) - Path Modeling. Most ponds had unusually shallow depths, characterized by excessive stocking densities of 200% on average above recommended rates. This necessitates high feeding rates, thereby reducing the assimilative capacity of ponds. The effect of feeding intensity on water quality increased with stock age. Persistent algal blooms, low DO, high temperatures and elevated levels of ammonia, nitrite, phosphate, TDS and conductivity were indicative of generally poor water quality. The model showed that 82 % variability in water quality was due to production inputs. Standard stocking rates, feeding rates and construction of deeper ponds are recommended.
This document discusses improving the quality of raw water used in hatcheries for culturing Oreochromis niloticus fingerlings. It outlines the methodology used which included three water treatment options - untreated raw water (TA), biologically sand filtered water (TB), and polypropylene cartridge filtered water (TC). Results showed TB had the highest survival rate (93.89%) and growth performance compared to the other treatments. Water quality parameters like temperature, pH, and dissolved oxygen were within acceptable ranges for tilapia culture across all treatments. Bacterial levels were lowest in TC. The study demonstrates that biological sand filtration is the best method for improving raw water quality in hatcheries.
Macedo et al (2015)-Irrigation Groundwater Quality for Agricultural UseJenkins Macedo
The document summarizes a study on assessing irrigation groundwater quality for agricultural use in Ekxang Village, Lao PDR. Daily field tests were conducted to measure parameters like EC, TDS, pH, and temperature of the groundwater. Laboratory analyses found that mean EC and SAR were below thresholds for crop tolerance, indicating groundwater quality was suitable for agriculture with low salinity and sodicity risks. While groundwater irrigation could help smallholders adapt to climate change, constant monitoring of quality is needed to sustainably increase crop yields and soil health.
This research aims to identify the most cost-effective combination of upland, riparian, and in-stream conservation practices to reduce sediment loads in the Fort Cobb watershed. Research includes modeling erosion under different land management scenarios and surveying stakeholders. Preliminary results show streambank erosion contributes significantly to sediment loads. Field studies quantified streambank erodibility, which varies within the watershed. Process-based models are being used to predict streambank erosion at site and reach scales. Landowner surveys found enrollment in conservation programs increases with farm revenue, education, and stewardship mindsets.
IRJET- Eutrophication Assessment of the Kelegeri Lake using GIS TechniqueIRJET Journal
This document summarizes a study assessing the eutrophication level of Kelegeri Lake in India using GIS techniques. Water samples were collected monthly from 7 locations around the lake from February to April 2019. The samples were analyzed to determine physico-chemical parameters like temperature, transparency, pH, COD, BOD, DO, nitrates and phosphates. Carlson's Trophic State Index was calculated based on secchi depth, total phosphorus and total nitrogen to classify the trophic state. Spatial distribution maps of parameters were developed using GIS. The results found the lake to be oligotrophic in February and April, mesotrophic in March, and in the moderately upper mesotrophic range overall during
This document summarizes findings from multiple watershed-scale studies on the effects of conservation practices conducted between 2004-2018 as part of the USDA CEAP program. Key findings include:
1) The implementation of conservation practices like cover crops, riparian buffers, and nutrient management plans effectively reduced nutrients and sediments in surface waters in several watersheds across the country.
2) Models were used to identify priority areas for conservation and predict load reductions, however watershed responses were complex and variations in practices and conditions made broad effects difficult to detect.
3) While edge-of-field water quality often improved with conservation practices, stream impacts were more dependent on factors like bank erosion and riparian conditions.
This study investigated nitrogen transformations in aquaponic systems under different conditions. The main findings were:
1) Nitrate continuously accumulated in the recirculating water, termed the "Balloon Effect", because nitrate input from fish waste exceeded plant uptake.
2) Denitrification, the conversion of nitrates/nitrites to nitrogen gas, was found to be the major source of nitrogen loss. Higher dissolved oxygen and lower feeding rates decreased denitrification.
3) Isotopic analysis showed denitrification rates were higher under low dissolved oxygen conditions, as evidenced by higher nitrate δ15N values. This supported denitrification as the primary nitrogen loss pathway.
This document summarizes a study on using saturated riparian buffers to remove nitrate from subsurface agricultural drainage. Key findings include:
- Saturated buffers significantly reduced nitrate levels in tile drainage water compared to conventional buffers, removing on average 80% of nitrate.
- Nitrous oxide emissions, a greenhouse gas, were higher in saturated buffer soils than conventional buffer soils but remained low overall.
- Saturated buffers are a promising alternative to conventional buffers for removing nitrate from tile drainage in agricultural landscapes and improving water quality.
This document summarizes research on managing a recirculating aquaculture system (RAS) to sustainably produce shrimp. The RAS was designed to conserve water, recycle nutrients, and prevent escapement of shrimp. Water quality parameters like dissolved oxygen, salinity, and ammonia were monitored daily or biweekly. Initial data showed difficulties maintaining adequate dissolved oxygen levels in the nursery and leaks in the RAS. With improvements to aeration and sealing, the RAS aims to provide a sustainable alternative to traditional aquaculture and fisheries facing declining yields.
This document discusses improving the quality of raw water used in hatcheries for culturing Oreochromis niloticus fingerlings. It outlines the methodology used which included three water treatment options - untreated raw water (TA), biologically sand filtered water (TB), and polypropylene cartridge filtered water (TC). Results showed TB had the highest survival rate (93.89%) and growth performance compared to the other treatments. Water quality parameters like temperature, pH, and dissolved oxygen were within acceptable ranges for tilapia culture across all treatments. Bacterial levels were lowest in TC. The study demonstrates that biological sand filtration is the best method for improving raw water quality in hatcheries.
Macedo et al (2015)-Irrigation Groundwater Quality for Agricultural UseJenkins Macedo
The document summarizes a study on assessing irrigation groundwater quality for agricultural use in Ekxang Village, Lao PDR. Daily field tests were conducted to measure parameters like EC, TDS, pH, and temperature of the groundwater. Laboratory analyses found that mean EC and SAR were below thresholds for crop tolerance, indicating groundwater quality was suitable for agriculture with low salinity and sodicity risks. While groundwater irrigation could help smallholders adapt to climate change, constant monitoring of quality is needed to sustainably increase crop yields and soil health.
This research aims to identify the most cost-effective combination of upland, riparian, and in-stream conservation practices to reduce sediment loads in the Fort Cobb watershed. Research includes modeling erosion under different land management scenarios and surveying stakeholders. Preliminary results show streambank erosion contributes significantly to sediment loads. Field studies quantified streambank erodibility, which varies within the watershed. Process-based models are being used to predict streambank erosion at site and reach scales. Landowner surveys found enrollment in conservation programs increases with farm revenue, education, and stewardship mindsets.
IRJET- Eutrophication Assessment of the Kelegeri Lake using GIS TechniqueIRJET Journal
This document summarizes a study assessing the eutrophication level of Kelegeri Lake in India using GIS techniques. Water samples were collected monthly from 7 locations around the lake from February to April 2019. The samples were analyzed to determine physico-chemical parameters like temperature, transparency, pH, COD, BOD, DO, nitrates and phosphates. Carlson's Trophic State Index was calculated based on secchi depth, total phosphorus and total nitrogen to classify the trophic state. Spatial distribution maps of parameters were developed using GIS. The results found the lake to be oligotrophic in February and April, mesotrophic in March, and in the moderately upper mesotrophic range overall during
This document summarizes findings from multiple watershed-scale studies on the effects of conservation practices conducted between 2004-2018 as part of the USDA CEAP program. Key findings include:
1) The implementation of conservation practices like cover crops, riparian buffers, and nutrient management plans effectively reduced nutrients and sediments in surface waters in several watersheds across the country.
2) Models were used to identify priority areas for conservation and predict load reductions, however watershed responses were complex and variations in practices and conditions made broad effects difficult to detect.
3) While edge-of-field water quality often improved with conservation practices, stream impacts were more dependent on factors like bank erosion and riparian conditions.
This study investigated nitrogen transformations in aquaponic systems under different conditions. The main findings were:
1) Nitrate continuously accumulated in the recirculating water, termed the "Balloon Effect", because nitrate input from fish waste exceeded plant uptake.
2) Denitrification, the conversion of nitrates/nitrites to nitrogen gas, was found to be the major source of nitrogen loss. Higher dissolved oxygen and lower feeding rates decreased denitrification.
3) Isotopic analysis showed denitrification rates were higher under low dissolved oxygen conditions, as evidenced by higher nitrate δ15N values. This supported denitrification as the primary nitrogen loss pathway.
This document summarizes a study on using saturated riparian buffers to remove nitrate from subsurface agricultural drainage. Key findings include:
- Saturated buffers significantly reduced nitrate levels in tile drainage water compared to conventional buffers, removing on average 80% of nitrate.
- Nitrous oxide emissions, a greenhouse gas, were higher in saturated buffer soils than conventional buffer soils but remained low overall.
- Saturated buffers are a promising alternative to conventional buffers for removing nitrate from tile drainage in agricultural landscapes and improving water quality.
This document summarizes research on managing a recirculating aquaculture system (RAS) to sustainably produce shrimp. The RAS was designed to conserve water, recycle nutrients, and prevent escapement of shrimp. Water quality parameters like dissolved oxygen, salinity, and ammonia were monitored daily or biweekly. Initial data showed difficulties maintaining adequate dissolved oxygen levels in the nursery and leaks in the RAS. With improvements to aeration and sealing, the RAS aims to provide a sustainable alternative to traditional aquaculture and fisheries facing declining yields.
This document summarizes a study that monitored water quality in five tributaries that provide 70% of inflow to Otsego Lake. It analyzed fecal coliform levels at 23 sites between May and July 2015 to track nonpoint sources of pollution. Key findings included: 1) Temperature, dissolved oxygen, pH, conductivity, and turbidity varied across sites and were consistent with past studies; 2) Fecal coliform levels suggested potential manure runoff or inadequately treated wastewater; 3) Best management practices had been implemented on farms near some sites to help reduce nutrient loading to the lake.
Effect of Salt and Water Stresses on Jujube Trees under Ras Sudr Conditionsiosrjce
This investigation was carried out during two successive seasons (2010 and 2011) on 5 years old
Nabq (Zizyphus spina christi) trees at Ras Suder Research Station, Desert Research Center- South Sinai
Governorate, Egypt. This investigation aimed to study the effect of saline water treatments, water regulation
and water irrigation levels on vegetative growth, some fruit parameters, leaf mineral contents, yield and fruit
quality. The treatments contained the combination of three main factors: The first factor: two wells as a saline
water source (well I and well II with EC values 3.68 and 6.80 dS/m, respectively). The second factor: water
regulation method (WR): DI= deficit irrigation and RDI = regulated deficit irrigation by partial root zone
drying (PRD). The third factor: irrigation levels of ETc = crop evapotranspiration 50, 75 and 100% (IL)). The
obtained results showed that well I X deficit irrigation (DI) & regulated deficit irrigation (RDI) X 100% gave
the highest values of tree circumference, Number shoots/tree, leaf area, yield/tree, fruit length, fruit diameter,
fruit weight, fruit volume, fruit flesh weight, fruit moisture% and leaf contents of N, P, Mg beside TSS and total
sugars. Moreover, treatments with well I X deficit irrigation (DI) recorded the highest values of shoot length,
shoot diameter, fruit set, fruit retention, K and Fe. We can be recommended by treatment of trees with well I
under stresses with regulated deficit irrigation under 100 % ETc to get the best results of fruit quality
This cruise summary report describes a research cruise conducted from May 17-24, 2015 that aimed to study the chronic effects of bottom trawling on benthic communities and fish in the Celtic Sea. A team of scientists from Spain and the UK sampled 12 stations in a Nephrops fishing ground using grabs to collect infauna, imaging to assess bioturbation, and trawls to collect fish and invertebrates. Bad weather limited sampling to 5 days, but replicate samples were collected at each station. Infauna and fish length and weight data were recorded to analyze impacts on community composition and trophic structure across a trawling gradient. Tissue samples were also taken for stable isotope analysis to further assess
Established the Environmental Monitoring Program Indicators to Prevent Diseas...CrimsonpublishersCJMI
Established the Environmental Monitoring Program Indicators to Prevent Disease Infection and Promote Sustainable Development by Yi-Che Shih in Cohesive Journal of Microbiology & Infectious Disease
This document summarizes research on phosphorus transport processes in Midwestern streams. It finds that stream banks and beds are major sources of phosphorus due to erosion. Methods to estimate bank erosion rates using LiDAR are presented. Sediment samples from different geological layers have distinct phosphorus retention properties. Restoration has not yet reduced sediment loads or bank erosion rates, indicating a slow transition from historical disturbance. Streambank erosion is a substantial source of phosphorus that restoration has not yet addressed.
The document summarizes a study that monitored water quality and benthic ecosystems around fish farms in Igoumenitsa Bay, Greece between 2011-2012. Water samples found increased nutrients like phosphorus near the fish farms, especially in summer, indicating localized eutrophication. A dispersion model showed waste from the farms could spread over 120 meters, mostly towards the coast. The benthic ecosystem was not significantly disturbed, though a biotic index found potential ecological risk in summer. Increased feeding and fish metabolism in summer, combined with seasonal currents, contributed to the localized nutrient increase near the farms.
This document summarizes an agent-based model of Atlantic salmon migration in Scottish coastal waters. The model uses data on salmon movements to simulate individual salmon searching for their home rivers along the coast. Initial results show the model can replicate some patterns from historical tagging studies. Further refinement is needed by incorporating more accurate estimates of river productivity and fishing effort data to improve matching with real data patterns. The next steps aim to test the model under different scenarios to better understand salmon migration behaviors.
utstanding Poster Contest winner at 36th Annual Oklahomaha Govern's Water ...saroj kandel
1) The document evaluates aged bioretention cells using fly ash as a filter media for enhanced phosphorus removal and water quality improvement.
2) Soil core samples were taken from five bioretention cells to quantify phosphorus accumulation in the filter media after seven years.
3) Stormwater monitoring of the cells showed 54-94% total phosphorus mass reduction and 14-82% ortho-phosphorus concentration reduction, indicating that fly ash improved phosphorus sorption in the bioretention cells over time.
This presentation was given at the EPA’s National Water Event 2019, which took place on 29 and 30 May 2019 in Galway. This presentation by Rebecca Jeffrey from NPWS is on the status of protected habitats and species in Ireland
Assessment of Water Quality Indices for Irrigation of Dharta Watershed, Udaip...ijtsrd
Validate the suitability of water for agriculture on the basis of the quality indices is the key objective of this study. The quality of water was evaluated by analyzing parameters such as calcium, magnesium, sodium, alkalinity and bicarbonates. The quality indices were evaluated and ranged as Sodium Absorption Ratio 0.54 to 5.80 ppm, Soluble Sodium percentage 10.47 to 59.17 ppm, Residual Sodium Carbonate 26.25 to 1.24 ppm, Permeability Index 25.16 to 79.78 and Kelly’s Ratio 0.12 to 1.45 ppm. The outcomes were compared to the WHO and BIS standards. According to salinity hazard in which based on EC, 18.33 samples are unsuitable for irrigation, while 26.67 samples are utilize by suitable water treatment, On the basis of TDS 5 of water samples are belongs to moderately saline category which is reduce by some irrigation practices. On the other side based on Sodium hazard all the samples are found within the range of excellent category, which means water is suitable for irrigation purpose. The calculated indices were fit in agreement by means of WHO and BIS. The documentation contains information about the impact of the irrigation water quality on the agriculture. Katara P. | Mittal H. K. | Maheshwari B. L. | Singh P. K. | Dashora Y. "Assessment of Water Quality Indices for Irrigation of Dharta Watershed, Udaipur, Rajasthan, India" Published in International Journal of Trend in Scientific Research and Development (ijtsrd), ISSN: 2456-6470, Volume-4 | Issue-3 , April 2020, URL: https://www.ijtsrd.com/papers/ijtsrd30429.pdf Paper Url :https://www.ijtsrd.com/engineering/agricultural-engineering/30429/assessment-of-water-quality-indices-for-irrigation-of-dharta-watershed-udaipur-rajasthan-india/katara-p
Researchers compared the growth, body condition, and survival of juvenile muskellunge reared in ponds with and without added structural habitat. They found that muskellunge reared in ponds with added structures like PVC pipes had greater growth, higher body condition, and higher relative survival compared to those reared in ponds without structures. While results were preliminary and from a single year of study with limited replication, the findings suggest adding structural habitat can benefit muskellunge production goals in hatchery settings by increasing growth, survival, and overall production. The study will continue for several years to obtain more data and detailed statistical analysis.
IRJET- A Seasonal Assessment of Groundwater Quality in Dharmapuri RegionIRJET Journal
This document analyzes seasonal groundwater quality in the Dharmapuri region of Tamil Nadu, India. 20 groundwater samples were collected from bore wells across the region in the pre-monsoon, post-monsoon, and pre-monsoon seasons. The samples were analyzed for various physicochemical parameters including turbidity, pH, EC, TDS, TH, and others. The results found that groundwater quality varied seasonally, with higher TDS values in pre-monsoon seasons indicating dilution during post-monsoon. Total hardness was generally high, making most groundwater unsuitable for drinking. Sodium percentage analysis showed water suitability ranged from excellent to unsuitable depending on location and season. The study assessed groundwater
This study examines the physicochemical controls on the transport of veterinary pharmaceuticals and hormones from animal manures to surface waters. The researchers investigated the long-term sorption kinetics of the antibiotic lincomycin on various biochars derived from animal manures. They also studied the sorption and transport of the hormone 17β-estradiol on biochars using batch experiments and fixed-bed column experiments. The results showed fast initial surface sorption and slower long-term pore diffusion of lincomycin onto the biochars. Additionally, biochar had a greater sorption capacity for 17β-estradiol than sand and reduced its transport compared to biochar-free sand in column experiments.
AQGR and Climate Change (Aquaculture and fisheries) reducedPatrick White
This document discusses the impacts of climate change on aquatic genetic resources and how aquatic species and ecosystems can both adapt to and mitigate the effects of climate change. It outlines various climate change stressors such as temperature fluctuations, precipitation changes, ocean acidification and sea level rise. It then examines the impacts of these stressors on different aquatic environments, ecosystems, species and fisheries and aquaculture. This includes impacts to key habitats like coral reefs, seagrass beds and mangroves, as well as different types of fisheries and aquaculture systems. The document provides graphics and tables to illustrate climate change impacts and risks.
The document summarizes data collected by volunteers from two streams, Delaware Creek and Coffee Creek, in Oklahoma. The volunteers measured physical habitat, collected fish and macroinvertebrates, and tested water chemistry. Delaware Creek had higher quality physical habitat and biological communities than Coffee Creek, indicating it is in better condition. Both streams are compared to a reference for their ecoregion.
Response aquatic systems and livelihoods to climate change presentation finalCANAAFRICA
This document summarizes how climate variability and change impact inland aquatic ecosystems, fisheries productivity, and livelihoods in Africa. It finds that temperatures have increased in African lakes since 1980s, affecting mixing dynamics and stratification. This caused shifts in aquatic organisms and fisheries toward faster growing species. Communities have adapted fishing methods and diversified livelihoods. However, more policy interventions are needed to support adaptation, mitigate impacts, and incorporate climate change into management.
Aquaculture is an important industry in Ireland, but can impact marine biodiversity and ecosystems. Researchers assessed these impacts and tested mitigation strategies. Pacific oysters were found to negatively impact protected habitats like Sabellaria reefs. Salmon cages lowered diversity near cages but effects extended hundreds of meters. Suspension feeders showed potential to reduce nutrient levels from cages. Future research is needed on wider-scale influences on communities and carrying capacities of bays.
Recirculating aquaculture systems (RAS) operate by filtering water from the fish (or shellfish) tanks so it can be reused within the tank. This dramatically reduces the amount of water and space required to intensively produce seafood products.
This document summarizes research on evergreen agriculture for sustainable intensification and resilience in the African drylands. The research examines the role of native shrub species, such as Guiera senegalensis and Piliostigma reticulatum, which are commonly found in farmers' fields. Several key findings are highlighted: 1) Shrubs provide significant carbon storage and inputs to soils. 2) Shrubs enhance water infiltration and groundwater recharge through hydraulic redistribution without competing with crops for water. 3) The shrub rhizosphere maintains high microbial activity and diversity year-round. The presence of shrubs has been shown to increase crop yields substantially.
Aquaculture is an important sector for Bangladesh's economy and food production, accounting for 5% of GDP and 6% of exports. However, many existing aquaculture practices are unsustainable, as they have led to environmental degradation like destruction of mangroves and wetlands for pond construction, soil acidification, and salinization of land and water. They have also negatively impacted livelihoods by reducing access to resources for local communities. Truly sustainable aquaculture requires practices that do not significantly disrupt ecosystems, are economically viable, and contribute to social well-being. Improving feed sources, closed containment systems, native species selection, and community inclusion can help make aquaculture more environmentally friendly and equitable.
Standard water quality requirements and management strategies for fish farmin...eSAT Journals
A study on standard water quality requirements and management strategies suitable for fish farming is presented. The water quality criteria studied based on physical, chemical and biological properties of water include temperature, turbidity, total suspended solids (TSS), total dissolved solid (TDS), nitrate- nitrogen, pH, biochemical oxygen demand (BOD) and total hardness. Water samples from Otamiri River in Imo state, Nigeria, were analyzed based on the afore-mentioned criteria to assess its suitability as a source of water for fish farming. The results of the analysis compared with international standards revealed that the river temperature of 26.90C, nitrate-nitrogen value of 0.015 mg/l and total suspended solids of 18.60 mg/l fall within the acceptable range for fish farming. However, the pH of 5.82, total hardness of 5.8 mg/l, total dissolved solids of 13.60 mg/l and biochemical oxygen demand of 0.6 mg/l all differed slightly from the standard recommended values. This study will aid fish farmers on the necessary treatment needed to effectively use water from this source for fish farming.
Keywords: Water quality criteria, Otamiri River, biochemical oxygen demand, total suspended and total dissolved solids.
This document summarizes a study that monitored water quality in five tributaries that provide 70% of inflow to Otsego Lake. It analyzed fecal coliform levels at 23 sites between May and July 2015 to track nonpoint sources of pollution. Key findings included: 1) Temperature, dissolved oxygen, pH, conductivity, and turbidity varied across sites and were consistent with past studies; 2) Fecal coliform levels suggested potential manure runoff or inadequately treated wastewater; 3) Best management practices had been implemented on farms near some sites to help reduce nutrient loading to the lake.
Effect of Salt and Water Stresses on Jujube Trees under Ras Sudr Conditionsiosrjce
This investigation was carried out during two successive seasons (2010 and 2011) on 5 years old
Nabq (Zizyphus spina christi) trees at Ras Suder Research Station, Desert Research Center- South Sinai
Governorate, Egypt. This investigation aimed to study the effect of saline water treatments, water regulation
and water irrigation levels on vegetative growth, some fruit parameters, leaf mineral contents, yield and fruit
quality. The treatments contained the combination of three main factors: The first factor: two wells as a saline
water source (well I and well II with EC values 3.68 and 6.80 dS/m, respectively). The second factor: water
regulation method (WR): DI= deficit irrigation and RDI = regulated deficit irrigation by partial root zone
drying (PRD). The third factor: irrigation levels of ETc = crop evapotranspiration 50, 75 and 100% (IL)). The
obtained results showed that well I X deficit irrigation (DI) & regulated deficit irrigation (RDI) X 100% gave
the highest values of tree circumference, Number shoots/tree, leaf area, yield/tree, fruit length, fruit diameter,
fruit weight, fruit volume, fruit flesh weight, fruit moisture% and leaf contents of N, P, Mg beside TSS and total
sugars. Moreover, treatments with well I X deficit irrigation (DI) recorded the highest values of shoot length,
shoot diameter, fruit set, fruit retention, K and Fe. We can be recommended by treatment of trees with well I
under stresses with regulated deficit irrigation under 100 % ETc to get the best results of fruit quality
This cruise summary report describes a research cruise conducted from May 17-24, 2015 that aimed to study the chronic effects of bottom trawling on benthic communities and fish in the Celtic Sea. A team of scientists from Spain and the UK sampled 12 stations in a Nephrops fishing ground using grabs to collect infauna, imaging to assess bioturbation, and trawls to collect fish and invertebrates. Bad weather limited sampling to 5 days, but replicate samples were collected at each station. Infauna and fish length and weight data were recorded to analyze impacts on community composition and trophic structure across a trawling gradient. Tissue samples were also taken for stable isotope analysis to further assess
Established the Environmental Monitoring Program Indicators to Prevent Diseas...CrimsonpublishersCJMI
Established the Environmental Monitoring Program Indicators to Prevent Disease Infection and Promote Sustainable Development by Yi-Che Shih in Cohesive Journal of Microbiology & Infectious Disease
This document summarizes research on phosphorus transport processes in Midwestern streams. It finds that stream banks and beds are major sources of phosphorus due to erosion. Methods to estimate bank erosion rates using LiDAR are presented. Sediment samples from different geological layers have distinct phosphorus retention properties. Restoration has not yet reduced sediment loads or bank erosion rates, indicating a slow transition from historical disturbance. Streambank erosion is a substantial source of phosphorus that restoration has not yet addressed.
The document summarizes a study that monitored water quality and benthic ecosystems around fish farms in Igoumenitsa Bay, Greece between 2011-2012. Water samples found increased nutrients like phosphorus near the fish farms, especially in summer, indicating localized eutrophication. A dispersion model showed waste from the farms could spread over 120 meters, mostly towards the coast. The benthic ecosystem was not significantly disturbed, though a biotic index found potential ecological risk in summer. Increased feeding and fish metabolism in summer, combined with seasonal currents, contributed to the localized nutrient increase near the farms.
This document summarizes an agent-based model of Atlantic salmon migration in Scottish coastal waters. The model uses data on salmon movements to simulate individual salmon searching for their home rivers along the coast. Initial results show the model can replicate some patterns from historical tagging studies. Further refinement is needed by incorporating more accurate estimates of river productivity and fishing effort data to improve matching with real data patterns. The next steps aim to test the model under different scenarios to better understand salmon migration behaviors.
utstanding Poster Contest winner at 36th Annual Oklahomaha Govern's Water ...saroj kandel
1) The document evaluates aged bioretention cells using fly ash as a filter media for enhanced phosphorus removal and water quality improvement.
2) Soil core samples were taken from five bioretention cells to quantify phosphorus accumulation in the filter media after seven years.
3) Stormwater monitoring of the cells showed 54-94% total phosphorus mass reduction and 14-82% ortho-phosphorus concentration reduction, indicating that fly ash improved phosphorus sorption in the bioretention cells over time.
This presentation was given at the EPA’s National Water Event 2019, which took place on 29 and 30 May 2019 in Galway. This presentation by Rebecca Jeffrey from NPWS is on the status of protected habitats and species in Ireland
Assessment of Water Quality Indices for Irrigation of Dharta Watershed, Udaip...ijtsrd
Validate the suitability of water for agriculture on the basis of the quality indices is the key objective of this study. The quality of water was evaluated by analyzing parameters such as calcium, magnesium, sodium, alkalinity and bicarbonates. The quality indices were evaluated and ranged as Sodium Absorption Ratio 0.54 to 5.80 ppm, Soluble Sodium percentage 10.47 to 59.17 ppm, Residual Sodium Carbonate 26.25 to 1.24 ppm, Permeability Index 25.16 to 79.78 and Kelly’s Ratio 0.12 to 1.45 ppm. The outcomes were compared to the WHO and BIS standards. According to salinity hazard in which based on EC, 18.33 samples are unsuitable for irrigation, while 26.67 samples are utilize by suitable water treatment, On the basis of TDS 5 of water samples are belongs to moderately saline category which is reduce by some irrigation practices. On the other side based on Sodium hazard all the samples are found within the range of excellent category, which means water is suitable for irrigation purpose. The calculated indices were fit in agreement by means of WHO and BIS. The documentation contains information about the impact of the irrigation water quality on the agriculture. Katara P. | Mittal H. K. | Maheshwari B. L. | Singh P. K. | Dashora Y. "Assessment of Water Quality Indices for Irrigation of Dharta Watershed, Udaipur, Rajasthan, India" Published in International Journal of Trend in Scientific Research and Development (ijtsrd), ISSN: 2456-6470, Volume-4 | Issue-3 , April 2020, URL: https://www.ijtsrd.com/papers/ijtsrd30429.pdf Paper Url :https://www.ijtsrd.com/engineering/agricultural-engineering/30429/assessment-of-water-quality-indices-for-irrigation-of-dharta-watershed-udaipur-rajasthan-india/katara-p
Researchers compared the growth, body condition, and survival of juvenile muskellunge reared in ponds with and without added structural habitat. They found that muskellunge reared in ponds with added structures like PVC pipes had greater growth, higher body condition, and higher relative survival compared to those reared in ponds without structures. While results were preliminary and from a single year of study with limited replication, the findings suggest adding structural habitat can benefit muskellunge production goals in hatchery settings by increasing growth, survival, and overall production. The study will continue for several years to obtain more data and detailed statistical analysis.
IRJET- A Seasonal Assessment of Groundwater Quality in Dharmapuri RegionIRJET Journal
This document analyzes seasonal groundwater quality in the Dharmapuri region of Tamil Nadu, India. 20 groundwater samples were collected from bore wells across the region in the pre-monsoon, post-monsoon, and pre-monsoon seasons. The samples were analyzed for various physicochemical parameters including turbidity, pH, EC, TDS, TH, and others. The results found that groundwater quality varied seasonally, with higher TDS values in pre-monsoon seasons indicating dilution during post-monsoon. Total hardness was generally high, making most groundwater unsuitable for drinking. Sodium percentage analysis showed water suitability ranged from excellent to unsuitable depending on location and season. The study assessed groundwater
This study examines the physicochemical controls on the transport of veterinary pharmaceuticals and hormones from animal manures to surface waters. The researchers investigated the long-term sorption kinetics of the antibiotic lincomycin on various biochars derived from animal manures. They also studied the sorption and transport of the hormone 17β-estradiol on biochars using batch experiments and fixed-bed column experiments. The results showed fast initial surface sorption and slower long-term pore diffusion of lincomycin onto the biochars. Additionally, biochar had a greater sorption capacity for 17β-estradiol than sand and reduced its transport compared to biochar-free sand in column experiments.
AQGR and Climate Change (Aquaculture and fisheries) reducedPatrick White
This document discusses the impacts of climate change on aquatic genetic resources and how aquatic species and ecosystems can both adapt to and mitigate the effects of climate change. It outlines various climate change stressors such as temperature fluctuations, precipitation changes, ocean acidification and sea level rise. It then examines the impacts of these stressors on different aquatic environments, ecosystems, species and fisheries and aquaculture. This includes impacts to key habitats like coral reefs, seagrass beds and mangroves, as well as different types of fisheries and aquaculture systems. The document provides graphics and tables to illustrate climate change impacts and risks.
The document summarizes data collected by volunteers from two streams, Delaware Creek and Coffee Creek, in Oklahoma. The volunteers measured physical habitat, collected fish and macroinvertebrates, and tested water chemistry. Delaware Creek had higher quality physical habitat and biological communities than Coffee Creek, indicating it is in better condition. Both streams are compared to a reference for their ecoregion.
Response aquatic systems and livelihoods to climate change presentation finalCANAAFRICA
This document summarizes how climate variability and change impact inland aquatic ecosystems, fisheries productivity, and livelihoods in Africa. It finds that temperatures have increased in African lakes since 1980s, affecting mixing dynamics and stratification. This caused shifts in aquatic organisms and fisheries toward faster growing species. Communities have adapted fishing methods and diversified livelihoods. However, more policy interventions are needed to support adaptation, mitigate impacts, and incorporate climate change into management.
Aquaculture is an important industry in Ireland, but can impact marine biodiversity and ecosystems. Researchers assessed these impacts and tested mitigation strategies. Pacific oysters were found to negatively impact protected habitats like Sabellaria reefs. Salmon cages lowered diversity near cages but effects extended hundreds of meters. Suspension feeders showed potential to reduce nutrient levels from cages. Future research is needed on wider-scale influences on communities and carrying capacities of bays.
Recirculating aquaculture systems (RAS) operate by filtering water from the fish (or shellfish) tanks so it can be reused within the tank. This dramatically reduces the amount of water and space required to intensively produce seafood products.
This document summarizes research on evergreen agriculture for sustainable intensification and resilience in the African drylands. The research examines the role of native shrub species, such as Guiera senegalensis and Piliostigma reticulatum, which are commonly found in farmers' fields. Several key findings are highlighted: 1) Shrubs provide significant carbon storage and inputs to soils. 2) Shrubs enhance water infiltration and groundwater recharge through hydraulic redistribution without competing with crops for water. 3) The shrub rhizosphere maintains high microbial activity and diversity year-round. The presence of shrubs has been shown to increase crop yields substantially.
Aquaculture is an important sector for Bangladesh's economy and food production, accounting for 5% of GDP and 6% of exports. However, many existing aquaculture practices are unsustainable, as they have led to environmental degradation like destruction of mangroves and wetlands for pond construction, soil acidification, and salinization of land and water. They have also negatively impacted livelihoods by reducing access to resources for local communities. Truly sustainable aquaculture requires practices that do not significantly disrupt ecosystems, are economically viable, and contribute to social well-being. Improving feed sources, closed containment systems, native species selection, and community inclusion can help make aquaculture more environmentally friendly and equitable.
Standard water quality requirements and management strategies for fish farmin...eSAT Journals
A study on standard water quality requirements and management strategies suitable for fish farming is presented. The water quality criteria studied based on physical, chemical and biological properties of water include temperature, turbidity, total suspended solids (TSS), total dissolved solid (TDS), nitrate- nitrogen, pH, biochemical oxygen demand (BOD) and total hardness. Water samples from Otamiri River in Imo state, Nigeria, were analyzed based on the afore-mentioned criteria to assess its suitability as a source of water for fish farming. The results of the analysis compared with international standards revealed that the river temperature of 26.90C, nitrate-nitrogen value of 0.015 mg/l and total suspended solids of 18.60 mg/l fall within the acceptable range for fish farming. However, the pH of 5.82, total hardness of 5.8 mg/l, total dissolved solids of 13.60 mg/l and biochemical oxygen demand of 0.6 mg/l all differed slightly from the standard recommended values. This study will aid fish farmers on the necessary treatment needed to effectively use water from this source for fish farming.
Keywords: Water quality criteria, Otamiri River, biochemical oxygen demand, total suspended and total dissolved solids.
The document discusses water quality issues in India. It states that over 60,000 Indian children under five die from diarrhea caused by unsafe water and poor sanitation annually. Water quality is affected by sewage, agricultural and urban runoff, and industrial discharge. Common contaminants include fluoride, arsenic, and nitrates from various sources. Monitoring of water quality is done across India through networks measuring various biological, physical, chemical and aesthetic parameters. However, many areas still face poor water quality posing health risks like cancer and fluorosis. Ensuring access to safe drinking water remains a key challenge.
This document presents information on a credit seminar about climate smart aquaculture and advisory services. It contains an introduction stating the objective is to assess the impact of climate change on fisheries and aquaculture and implement better farming technologies. It then discusses topics like food security, climate change causes and impacts, the role of aquaculture in climate change, climate smart aquaculture practices and technologies, supporting institutions, advisory services, and conclusions.
UK water quality 10UK water qualityCourse.docxmarilucorr
UK water quality 10
UK water quality
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Why water quality has deteriorated
Introduction
According to Boyd, (2015) water quality is the physical, biological, radiological and chemical components of water. Water quality can also be defined as a measure of the condition of water of one or more biotic species for use by human beings, animals, aquatic organisms or any other purposes. Lastly, water quality can also be defined as how suitable water can be used for different purposes.
Determination of water quality
The quality of water that is on earth is a function of (affected by) either natural influences or human activities. Water quality is determined by determining the weathering of bedrock minerals in the scenario where there is no human interference, (Chapman 2016). It is an atmospheric process of deposition of dust and, salt by the wind, and evapotranspiration, leaching of natural organic materials and the nutrients runoff in soil. Runoff which is caused by hydrological factors and a biological process in the aquatic environment can lead to changes in the physical and chemical constituents of water, (Ahuja 2013).
Water quality is determined by comparing the chemical and physical characteristics of a water sample according to the existing standards (guidelines). Regarding determining the quality of water for drinking, the standards are set so as to ensure that the drinking water is safe and clean for human consumption, (De Zuane, 1997). Attainment of these standards is through checking of the toxic levels so as to learn whether the water is fit for drinking by humans or even animals (which includes aquatic animals.)
Water quality indicators.
According to regional aquatics monitoring program, water quality is defined as the concentration physical and chemical components. Water quality indicators include: metals, conductivity, nutrients, dissolved oxygen, industrial chemicals (dioxins and PCBs), temperature, hydrocarbons and lastly, the conventional variables- (dissolved wastes, suspended sentiments, pH levels)
Has water quality deteriorated or improved?
In the recent years, water levels across the world have been declining, Ahuja (2013). Reasons attributed to the deterioration of water quality levels are: a fast growing human population, increased agricultural activities, expanding industrialization, irrigation, and the ever changing weather and climatic conditions, (Terrell & Perfetti, 1992). These reasons are such a threat to the hydrological cycle leading to increased pollution which in return adds up to the low-quality levels of water.
According to Boyd, (2000), at the moment, the largest water quality problem is eutrophication, which is caused by high levels of nitrogen and phosphorous which damage the water uses. Many nutrient sources consist of indoor pollution, agricultural runoff, industrial waste release, and atmospheric components of fossil fuels and other fires. According to World Health ...
AQUATIC GENETIC RESOURCES AND CLIMATE CHANGE_CleanPatrick White
This document provides an overview of the importance of aquatic genetic resources in the context of climate change. It discusses how aquatic ecosystems and the organisms they support play a key role in global carbon and nutrient cycles. Aquatic genetic resources underpin global aquaculture and fisheries, which together provide about half of the world's food fish and are important for food security, nutrition, and livelihoods. Climate change poses challenges for these resources and the sectors that depend on them through impacts like warming, acidification, and changes to freshwater availability. The roles of aquatic genetic resources in adapting to and mitigating climate change impacts are discussed.
Frequently occurring Harmful algal blooms in marine and Freshwater aquatic environment and their impacts noticed in various parts of the world. Focused studies by authors from different locations on HAB's controlling methods
Environmental and Social Risks and Solution Criteria in Offshore Aquaculture ...IJERA Editor
Aquaculture is a sector that involves agricultural activities aiming to meet the increasing animal food demand, contribute to balanced and healthy diet and reduce the hunting pressure on natural fish stocks. In aquaculture activities in sea, producers who are aware of the major role of obtaining an ecological balance in production regard coast utilization and environmental management as a part of production. Therefore, determination of environmental factors in production activities is highly important for sustainable aquaculture. The present study aims to determine the environmental risks and solution criteria in offshore aquaculture systems in Turkish seas. Environmental and social risks in production are collected under the main headings comprising nutrient and waste load in water, feeding, overuse of antibiotics and chemicals, fish escape, diseases, working conditions and common areas; solution criteria are collected under the main headings comprising ecosystem, water management, feed properties, legal procedure, chemical use, field management and occupational health and safety.
Production performance of whiteleg shrimp Litopenaeus vannamei at different s...UniversitasGadjahMada
This study examined the effects of different stocking densities on production performance of whiteleg shrimp (Litopenaeus vannamei) cultured in sandy ponds with plastic mulch. Shrimp were stocked at densities of 100, 200, and 300 shrimp/m2 and reared for 75 days. Results showed that final weight, daily growth rate, and survival rate decreased with increasing density, while feed conversion ratio and biomass production increased. The lowest density of 100 shrimp/m2 resulted in the highest final weight of 12.93g, growth rate of 0.1526g/day, and survival rate of 96.54%, but the lowest biomass production of 14.99kg/m2. Water
2011 nutrient enrichment caused by marine cageearambulm3
This document summarizes a study that evaluated the influence of marine cage aquaculture on coral reef communities in turbid waters near Penghu Islands, Taiwan. The study found that levels of ammonium, nitrite, and chlorophyll a released from fish cages distinguished the area closest to the cages (Impact Zone 1) from areas further away (Impact Zone 2 and the reference zone). Coral communities closest to the cages were dominated by stress-tolerant coral species while areas further away supported more diverse coral morphologies. The results suggest that nutrient enrichment from the fish cages is deteriorating suitable habitat for coral reef organisms at the study site.
Assessment of nutritive values of some waterweedsAlexander Decker
This document summarizes a study that evaluated the nutritive values and phytochemical constituents of 10 common waterweeds in Nigeria. The study found that the waterweeds contained 13.67-32.67% crude protein, 4-26% crude fiber, and 7.33-26% ash. The waterweeds also had adequate levels of other nutrients. Though high in moisture, the waterweeds could provide a source of nutrients, especially protein, for livestock during dry seasons. Qualitative analysis found that most waterweeds contained steroids, while four contained saponins and some contained phenols or tannins. Nymphaea lotus was found to have the lowest levels of anti-
Socio-Economic and Environmental Implication’s of Shrimp Cultivation in Andhr...Ruby Med Plus
Impromptu and random expansion of shrimp cultivation is happening in coastal regions of Andhra Pradesh. The exploration of its adverse effects has not received significant attention from the Indian researcher community yet. The shrimp industry is polluting and degrading soils,
water, mangroves, and forests. The sustainable productivity of ecosystems, biodiversity and public health is endangering year after year. Shrimp aquaculture is changing customary patterns of natural resource use by appropriating these resources for its own purposes while restricting rights of local users as coastal Andhra big and experienced farmers in the aqua field are making huge investments in the sector and purchasing the agriculture fields of small farmers to convert it into aqua ponds. This in turn affects livelihoods more widely by disrupting earlier systems of production, distribution and social relations.
In order to elicit the concomitant socio-economic impacts and propose environmental sustainable solutions of shrimp cultivation based on secondary data, the present study was conducted by applying ‘Systematic Review and Content Analysis’ as a research method. The study findings manifest that the constant and unregulated shrimp farming has immense impacts on human health, ecology, environment and sustainability other than economic benefits to aqua farm
owners. The extensive shrimp farming in coastal areas of Andhra Pradesh has negatively expedited the infringement of mangroves, intrusion of salinity, degradation of land, destabilization of coastal ecosystems. The main socio-economic effects challenge the patterns of
livelihood pattern, displacement of family and social structure, internal migration, reduction in grazing field and livestock, changes in the cropping calendar and its pattern and bio-diversity.
The Government of Andhra Pradesh and the financial institutions sponsoring shrimp cultivation has overlooked the impact of shrimp farming on Ecological and sustainability of farm fields and
control of salinity and degradation of mangrooves. In conclusion, appropriate adoption and implementation of the resilient strategies can reduce the adverse effects on the coastal environment, and improve the impact of unplanned shrimp cultivation in Andhra Pradesh and
other parts of India.
Organic and inorganic nutrient sources influeced growth, flowering, fruition,...Innspub Net
Fruit relative water content, carotenoid total chlorophyll content, flowering, fruition, growth and yield parameters of pepper (Capsicum annuum L.) cultivars: ‘Granada’, ‘Goliath’ and ‘Nobili’ were evaluated under two level of irrigation water: tap water (control) and tap water + 50mm NaCl, organic and inorganic fertilization in order to determine the field performance, for the improvement of smallholder agriculture in Cameroon. Four fertilizer application rates (0, 3, 6 and 12 t.ha-1) of Water Lettuce (WL) and Poultry Manure (PM) and 100kg/ha of NPK were used in a randomized complete block design experiment with four replications. The results overall indicated that the raising of fertilizer application rate of PM an WL increased significatively (p<0.05) carotenoid content, fruit water content, growth and agronomical parameters and decreased the date of flowering and fruition for all varieties studied compared to the control and NPK fertilizer, and what it regardless of the level of salinity. Application of WL or PM at 12 t ha-1 and NPK significantly increased fruit water content, growth and yield parameters in Granada compared to other cultivars. Irrigation of saline water decreased significantly (p<0.05) growth and yield parameters of all varieties. Significant (p<0.05) increased in growth parameters was observed in all cultivars at NPK fertilization. ‘Granada’ showed better growth and yield than ‘Nobili’ and ‘Goliath’ revealing a greater response of this cultivar to fertilization. This study is important contribution to identify tolerant cultivars for salt stress and permit to restore soil fertility and increase yield in coastal areas in Cameroun througth culture of Granada tolerant’s cultivar for salt stress.
Contribution of aquaculture on livelihood development of fish farmer at Noakh...AbdullaAlAsif1
The present study was conducted to assess the contribution of aquaculture on livelihood status of fish farmer at Noakhali sadar upazila. This research work was carried out during the period of February 2013 to July 2013. A total of 50 fish farmers were interviewed with a well-structured questionnaire. The survey revealed that average pond size was 0.48 ha with 40% of the farmers having ponds of single ownership, 20% having ponds of multiple-ownership, 30% having ponds of single lease and 10% having ponds of multiple leases. Poly culture of Indian major carps and exotic carps has been practiced by most of the farmers. Fish fingerlings were stocked from April to June and average stocking density was 12,370 fingerlings/ha. The average fish production cost was Tk 69,870/ha/yr. Although the living condition of the rural fish farmers were poor, livelihood outcomes were found positive and 88% of the farmers have improved their socioeconomic conditions through fish farming. The gross income and net profit were Tk. 1, 06,400 and Tk. 1, 00,000/ha/yr respectively. The average monthly income was in range of BDT 15,000-25,000. Their basic need like food, cloth, house, education and medical facility had changed after fish farming. The households have broadly improved their food consumption, family education, standards of living, purchasing power, choice and economic ability through fish farming. The constraints for sustainable pond fish farming in the areas were lack of technical knowledge of the farmers, disease of fishes, multiple ownership of the pond, higher production cost (mainly seeds and feed), insufficient supply of fry and fingerlings, lack of money and credit facilities and inadequate extension services. It is therefore essential to provide the necessary training facilities with institutional and organizational supports, credit facilities and extension services for sustainable fish production and livelihoods of rural fish farmers.
Effect of water parameters on temporal distribution and abundance of zooplank...AbdullaAlAsif1
Seasonal abundance of zooplankton in relation to different physico-chemical conditions of Kaptai lake has been studied. A total of four major groups of zooplankton were identified from study area of Kaptai lake during three seasons observation at pre-monsoon, monsoon and Post-monsoon. These four groups were categorized into rotifers, copepods, cladocerans and others (fish larvae, shrimp larvae, insects, mosquito larvae etc.). The mean abundance of group rotifers, copepods, cladoceras and others were 103, 84.67, 38.33 and 41.83 ind. L-1 respectively. The highest group was rotifers in terms of abundance and composition where compositions were recorded 38 % at three season's observation. The lowest group was cladoceras in term of abundance and composition where compositions were recorded 14 %. The air temperature, water temperature, transparency, water pH, DO, BOD5, PO 4-P, NO 2-N, SiO 3-Si, TSS, TDS, Alkalinity ranged between 21 and 27.5C, 23.5 and 31.5C, 0.8 and 3 m, 7.1 and 7.5, 5.72 and 8.58 mg/l, 8.55 and 12.87 mg/l, 3.22 and 4.13 µg/l, 0.992 and 1.19 µg/l, 161.18 and 201.15 µg/l, 0.28 and 0.48 g/l, 0.18 and 0.68 g/l, 40 and 60 ppm, respectively. Margalef richness index (d), Pielou's evenness index (J'), Shannon-Wiener diversity index (H'), Simpson dominance index (λ) are analyzed by Primer V6 software to quantify the collected species. Through same software SIMPER, Cluster analysis also done to compare similarity between season.
Effects of pH, Dosage, Temperature and Mixing Speed on The Efficiency of Wate...IJAEMSJORNAL
Studies were carried out to determine the effects of operating parameters such as temperature, pH, dosage and mixing speed on the efficiency of watermelon seed in removing the turbidity and colour of Atabong River, which serves the people of Eket and their environs in Akwa-Ibom State. Results obtained showed that at an ideal pH of 7.5, temperature of 25oC, dosage of 0.6g/l and mixing speed of 120rpm the water melon coagulum removed turbidity and colour of the raw river water by 87.9% and 84.3% respectively. At this optimum conditions, water melon coagulum decreased the raw water turbidity from 67.7 to 8.18 NTU and colour, 318 to 50 TCU. The findings have demonstrated the effectiveness of water melon seeds as a possible replacement for chemicals like alum and ferric salts normally used in coagulation-flocculation water treatment.
This document summarizes factors that affect water quality and its degradation. It discusses how human activities impact both water quality and quantity on various scales. Upstream human impacts on water quality can negatively affect downstream users as pollutants are transported through watersheds. Effective management requires recognizing how human activities can cyclically and cascadingly impact water quality and quantity along hydrologic pathways.
The Vietnam National Mekong Committee conducted a Mekong Dam Study, the results of which were presented at the Greater Mekong Forum on Water, Food and Energy in Phnom Penh on Oct. 21, 2015. This presentation overviews their Fisheries Impact Assessment.
Marine&FreshWater_Resources_Summer_14.pptAkash saha
Bangladesh has significant marine and freshwater fisheries resources due to its large aquatic biodiversity and vast wetland and river systems. It is one of the top fish producing nations. However, these resources are declining due to habitat loss, pollution, overfishing, and climate change impacts like rising temperatures and sea levels. Successful management requires better research, regulation, and ecosystem-based approaches that address threats like water degradation and ensure access for poor communities.
Similar to Understanding Water Quality Dynamics in Aquaculture Ponds in Sunyani, Ghana: Insights from Partial Least Squares (PLS) - Path Modeling (20)
Evaluation of Agro-morphological Performances of Hybrid Varieties of Chili Pe...Premier Publishers
In Benin, chilli pepper is a widely consumed as vegetable whose production requires the use of performant varieties. This work assessed, at Parakou and Malanville, the performance of six F1 hybrids of chilli including five imported (Laali, Laser, Nandi, Kranti, Nandita) and one local (De cayenne), in completely randomized block design at four replications and 15 plants per elementary plot. Agro-morphological data were collected and submitted to analysis of variance and factor analysis of mixed data. The results showed the effects of variety, location and their interactions were highly significant for most of the growth, earliness and yield traits. Imported hybrid varieties showed the best performances compared to the local one. Multivariate analysis revealed that 'De cayenne' was earlier, short in size, thin-stemmed, red fruits and less yielding (≈ 1 t.ha-1). The imported hybrids LaaliF1 and KrantiF1 were of strong vegetative vigor, more yielding (> 6 t.ha-1) by developing larger, long and hard fruits. Other hybrids showed intermediate performances. This study highlighted the importance of imported hybrids in improving yield and preservation of chili fruits. However, stability and adaptation analyses to local conditions are necessary for their adoption.
An Empirical Approach for the Variation in Capital Market Price Changes Premier Publishers
The chances of an investor in the stock market depends mainly on some certain decisions in respect to equilibrium prices, which is the condition of a system competing favorably and effectively. This paper considered a stochastic model which was latter transformed to non-linear ordinary differential equation where stock volatility was used as a key parameter. The analytical solution was obtained which determined the equilibrium prices. A theorem was developed and proved to show that the proposed mathematical model follows a normal distribution since it has a symmetric property. Finally, graphical results were presented and the effects of the relevant parameters were discussed.
Influence of Nitrogen and Spacing on Growth and Yield of Chia (Salvia hispani...Premier Publishers
Chia is an emerging cash crop in Kenya and its production is inhibited by lack of agronomic management information. A field experiment was conducted in February-June and May-August 2021, to determine the influence of nitrogen and spacing on growth and yield of Chia. A randomized complete block design with a split plot arrangement was used with four nitrogen rates as the main plots (0, 40, 80, 120 kg N ha-1) and three spacing (30 cm x 15 cm (s1), 30 cm x 30 cm (s2), 50 cm x 50 cm (s3)). Application of 120 kg N ha-1 significantly increased (p≤0.05) vegetative growth and seed yield of Chia. Stem height, branches, stem diameter and leaves increased by 23-28%, 11-13%, 43-55% and 59-88% respectively. Spacing s3 significantly increased (p≤0.05) vegetative growth. An increase of 27-74%, 36-45% and 73-107% was recorded in number of leaves, stem diameter and dry weight, respectively. Chia yield per plant was significantly higher (p≤0.05) in s3. However, when expressed per unit area, s1 significantly produced higher yields. The study recommends 120 kg N ha-1 or higher nitrogen rates and a closer spacing of 15 cm x 30 cm as the best option for Chia production in Kenya.
Enhancing Social Capital During the Pandemic: A Case of the Rural Women in Bu...Premier Publishers
The document discusses a case study of enhancing social capital among rural women in Bukidnon Province, Philippines during the COVID-19 pandemic through a livelihood project. Key findings include:
1) Technical trainings provided by the project increased the women's knowledge, allowing them to generate additional household income through vegetable gardening during the pandemic.
2) The women's social capital, as measured by groups/networks, trust, and cooperation, increased by 15.5% from 2019 to 2020 through increased participation in their association.
3) Main occupations, income sources, and ethnicity influenced the women's social capital. The project enhanced social ties that empowered the rural women economically and socially despite challenges of the pandemic.
Impact of Provision of Litigation Supports through Forensic Investigations on...Premier Publishers
This paper presents an argument through the fraud triangle theory that the provision of litigation supports through forensic audits and investigations in relation to corporate fraud cases is adequate for effective prosecution of perpetrators as well as corporate fraud prevention. To support this argument, this study operationalized provision of litigation supports through forensic audit and investigations, data mining for trends and patterns, and fraud data collection and preparation. A sample of 500 respondents was drawn from the population of professional accountants and legal practitioners in Nigeria. Questionnaire was used as the instrument for data collection and this was mailed to the respective respondents. Resulting responses were analyzed using the OLS multiple regression techniques via the SPSS statistical software. The results reveal that the provision of litigation supports through forensic audits and investigations, fraud data mining for trends and patterns and fraud data collection and preparation for court proceedings have a positive and significant impact on corporate fraud prevention in Nigeria. This study therefore recommends that regulators should promote the provision of litigation supports through forensic audits and investigations in relation to corporate fraud cases in publicly listed firms in Nigeria, as this will help provide reports that are acceptable in court proceedings.
Improving the Efficiency of Ratio Estimators by Calibration WeightingsPremier Publishers
It is observed that the performances of most improved ratio estimators depend on some optimality conditions that need to be satisfied to guarantee better estimator. This paper develops a new approach to ratio estimation that produces a more efficient class of ratio estimators that do not depend on any optimality conditions for optimum performance using calibration weightings. The relative performances of the proposed calibration ratio estimators are compared with a corresponding global [Generalized Regression (GREG)] estimator. Results of analysis showed that the proposed calibration ratio estimators are substantially superior to the traditional GREG-estimator with relatively small bias, mean square error, average length of confidence interval and coverage probability. In general, the proposed calibration ratio estimators are more efficient than all existing estimators considered in the study.
Urban Liveability in the Context of Sustainable Development: A Perspective fr...Premier Publishers
Urbanization and quality of urban life are mutually related and however it varies geographically and regionally. With unprecedented growth of urban centres, challenge against urban development is more in terms of how to enhance quality of urban life and liveability. Making sense of and measuring urban liveability of urban places has become a crucial step in the context of sustainable development paradigm. Geographical regions depict variations in nature of urban development and consequently level of urban liveability. The coastal regain of West Bengal faces unusual challenges caused by increasing urbanization, uncontrolled growth, and expansion of economic activities like tourism and changing environmental quality. The present study offers a perspective on urban liveability of urban places located in coastal region comprising of Purba Medinipur and South 24 Parganas districts. The study uses the liveability standards covering four major pillars- institutional, social, economic and physical and their indicators. This leads to develop a City Liveability Index to rank urban places of the region, higher the index values better the urban liveability. The data for the purpose is collected from various secondary sources. Study finds that the eastern coastal region of the country covering state of West Bengal depicts variations in index of liveability determined by physical, economic, social and institutional indicators.
Transcript Level of Genes Involved in “Rebaudioside A” Biosynthesis Pathway u...Premier Publishers
Stevia rebaudiana Bertoni is a plant which has recently been used widely as a sweetener. This medicinal plant has some components such as diterpenoid glycosides called steviol glycosides [SGs]. Rebaudioside A is a diterpenoid steviol glycoside which is 300 times sweeter than table sugar. This study was done to investigate the effect of GA3 (50 mg/L) on the expression of 14 genes involved in Rebaudioside A biosynthesis pathway in Stevia rebaudiana under in vitro conditions. The expression of DXS remarkably decreased by day 3. Also, probably because of the negative feedback of GA3 on MEP-drived isoprenes, GGDS transcript level reached its lowest amount after GA3 treatment. The abundance of DXR, CMS, CMK, MCS, and CDPS transcripts showed a significant increase at various days after this treatment. A significant drop in the expression levels of KS and UGT85C2 is detected during the first day. However, expression changes of HDR and KD were not remarkable. Results revealed that the level of transcript of UGT74G1 and UGT76G1 up regulated significantly 4 and 2 times higher than control, respectively. However, more research needs to shed more light on the mechanism of GA3 on gene expression of MEP pathway.
Multivariate Analysis of Tea (Camellia sinensis (L.) O. Kuntze) Clones on Mor...Premier Publishers
Information on genetic variability for biochemical characters is a prerequisite for improvement of tea quality. Thirteen introduced tea clones characterized with objective; assessing tea clones based on morphological characters at Melko and Gera research stations. The study was conducted during 2017/18 cropping season on experimental plots in RCBD with three replications. Data recorded on morphological traits like days from pruning to harvest, height to first branch, stem diameter, leaf serration density, leaf length, leaf width, leaf size, petiole length, leaf ratio, internode length, shoot length, number of shoot, canopy diameter, hundred shoot weight, fresh leaf yield per tree. Cluster analysis of morphological trait grouped into four clusters indicated, the existence of divergence among the tested clones. The maximum inter-cluster distance was between clusters I and IV (35.27) while the minimum inter cluster distance was observed between clusters I and II (7.8).Principal components analysis showed that the first five principal components with eigenvalues greater than one accounted 86.45% for 15 morphological traits. Generally, the study indicated presence of variability for several morphological traits. However, high morphological variation between clones is not a guarantee for a high genetic variation; therefore, molecular studies need to be considered as complementary to biochemical studies.
Causes, Consequences and Remedies of Juvenile Delinquency in the Context of S...Premier Publishers
This research work was designed to examine nature of juvenile offences committed by juveniles, causes of juvenile delinquency, consequences of juvenile delinquency and remedies for juvenile delinquency in the context of Sub-Saharan Africa with specific reference to Eritrea. Left unchecked, juvenile delinquents on the streets engage in petty theft, take alcohol or drugs, rape women, rob people at night involve themselves in criminal gangs and threaten the public at night. To shed light on the problem of juvenile delinquency in the Sub-Saharan region data was collected through primary and secondary sources. A sample size of 70 juvenile delinquents was selected from among 112 juvenile delinquents in remand at the Asmara Juvenile Rehabilitation Center in the Eritrean capital. The study was carried out through coded self-administered questionnaires administered to a sample of 70 juvenile delinquents. The survey evidence indicates that the majority of the juvenile respondents come either from families constructed by unmarried couples or separated or divorced parents where largely the father is missing in the home or dead. The findings also indicate that children born out of wedlock, families led by single mothers, lack of fatherly role models, poor parental-child relationships and negative peer group influence as dominant causes of juvenile infractions. The implication is that broken and stressed families are highly likely to be the breeding grounds for juvenile delinquency. The survey evidence indicates that stealing, truancy or absenteeism from school, rowdy or unruly behavior at school, free-riding in public transportation, damaging the book of fellow students and beating other young persons are the most common forms of juvenile offenses. It is therefore, recommended that parents and guardians should exercise proper parental supervision and give adequate care to transmit positive societal values to children. In addition, the government, the police, prosecution and courts, non-government organizations, parents, teachers, religious leaders, education administrators and other stakeholders should develop a child justice system that strives to prevent children from entering deeper into the criminal justice process.
The Knowledge of and Attitude to and Beliefs about Causes and Treatments of M...Premier Publishers
Stigma and discrimination associated with mental illness are a common occurrence in the Sub-Saharan region including Eritrea. Numerous studies from Sub-Saharan Africa suggest that stigma and discrimination are major problems in the community, with negative attitudes and behavior towards people with mental illness being widespread. In order to assess the whether such negative attitudes persist in the context of Eritrea this study explored the knowledge and perceptions of 90 Eritrean university students at the College of Business and Economics, the University of Asmara regarding the causes and remedies of mental illness A qualitative method involving coded self-administered questionnaires administered to a sample of 90 university students to collecting data at the end of 2019. The survey evidence points that almost 50% of the respondents had contact with a mentally ill person suggesting that the significant number of the respondents experienced a first-hand encounter and knowledge of mental illness in their family and community. The findings show an overall greater science-based understanding of the causes of mental illness to be followed by recommended psychiatric treatments. The survey evidence indicates that the top three leading causes of mental illness in the context of Eritrea according to the respondents are brain disease (76%), bad events in the life of the mentally ill person (66%) and substance abuse or alcohol taking, smoking, taking drugs like hashish. (54%). The majority of the respondents have a very sympathetic and positive outlook towards mentally ill persons suggesting that mentally illness does not simply affect a chosen individual rather it can happen to anybody regardless of economic class, social status, ethnicity race and religion. Medical interventions cited by the majority of the respondents as being effective treatments for mental illness centered on the idea that hospitals and clinics for treatment and even cures for psychiatric disease. Changing perceptions of mental illnesses in Eritrea that paralleled the very caring and sympathetic attitudes of the sample university students would require raising public awareness regarding mental illness through education, using the mass media to raise public awareness, integrating mental health into the primary health care system, decentralizing mental health care services to increase access to treatment and providing affordable service to maintain positive treatment outcomes.
Effect of Phosphorus and Zinc on the Growth, Nodulation and Yield of Soybean ...Premier Publishers
This study investigated the effects of phosphorus and zinc on the growth, nodulation, and yield of two soybean varieties in Nigeria. Phosphorus application significantly affected growth, nodulation, yield, and some yield components, with 60 kg P2O5/ha giving the highest growth and yield. Phosphorus also increased nodulation, with 30 kg P2O5/ha providing the highest nodulation. Zinc application did not significantly affect most growth characters or nodulation, except for reducing plant height. Phosphorus increased soybean yield significantly to 1.9 t/ha compared to the control of 1.7 t/ha. Protein and oil contents were not significantly affected by phosphorus but were by zinc
Influence of Harvest Stage on Yield and Yield Components of Orange Fleshed Sw...Premier Publishers
A field experiment was conducted at Adami Tullu Agricultural Research Center in 2018 under rainfed condition with supplementary irrigation to determine the influence of harvest stage on vine yield and tuberous root yield of orange fleshed sweet potato varieties. The experiment consisted of four harvest stages (105, 120, 135 and 150 days after planting) and Kulfo, Tulla and Guntute varieties. A 4 X 3 factorial experiment arranged in randomized complete block design with three replications was used. Interaction of harvest stage and variety significantly influenced above ground fresh biomass, vine length, marketable tuberous root weight per hectare, commercial harvest index and harvest index. The highest mean values of above ground fresh biomass (66.12 t/ha) and marketable tuberous root weight (56.39 t/ha) were produced by Guntute variety harvested at 135 days after planting. Based on the results, it can be recommended that, farmers of the study area can grow Guntute variety by harvesting at 135 days after planting to obtain optimum vine and tuberous root yields.
Performance evaluation of upland rice (Oryza sativa L.) and variability study...Premier Publishers
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2. Understanding Water Quality Dynamics in Aquaculture Ponds in Sunyani, Ghana: Insights from Partial Least Squares (PLS) - Path Modeling
Otoo et al. 029
A variety of factors interact to influence the water quality
characteristics in a culture system. These are soil
properties of site selected for aquaculture, chemical
composition of source water, atmospheric deposition,
management inputs and pollutants from anthropogenic-
driven activities in the watershed which come into contact
with water used in aquaculture production (Adhikari,
2003). Once in the pond system, the constituents of water
quality may act individually or in concert to determine
conditions that potentially cause lethal or sub-lethal effects
on fish health (El- Sayed, 2002). Furthermore, the
interactions of physical, chemical, biological factors and
management inputs create dynamic and complex
environments that influence water quality and
consequently fish health (Alemu, 2003). Despite this
diversity of factors potentially influencing water quality,
evidence suggests that production activities associated
with culturing fish constitute the major determinants of
water quality (Shoko et al., 2011). Two broad groups of
water quality variables have been classified on the basis
of their functional role in pond ecosystem dynamics (Boyd
and Tucker 1998). They are those set of variables such as
alkalinity, turbidity, salinity and compounds of phosphorus
and nitrogen are known to affect pond ecosystem primary
productivity, and those classified as critical water quality
factors such as dissolved oxygen, ammonia and carbon
dioxide which affect fish physiology and growth (Boyd and
Tucker 1998). Important parameters commonly measured
in routine assessments of water quality include nitrite,
ammonia (ionized NH4
+ and unionize NH3), dissolved
oxygen, pH, carbon dioxide, phosphate, conductivity,
temperature, total dissolved solids, salinity and
transparency.
Optimum fish yield is affected principally by the impact of
managerial practices on water quality (Boyd and Tucker
1998). Management input drives various water quality
conditions through the choice of culture species,
production levels, stocking density, feeding rates, stock
age and feed type (Boyd and Tucker, 1998). These factors
are known to be central to water quality and their effective
control can lead to good water quality management and
efficiency in production (Boyd and Tucker, 1998). High
stocking density influence feeding rates, nitrate-nitrogen
concentrations in water and their interactions with pH
which affects ammonia levels resulting in significant stress
and growth inhibition in fish (Shoko, 2014). Dissolved
oxygen, temperature, pH and ammonia, also parameters
of major concern, vary diurnally with peak values of some
variables occurring during the afternoon to pre-sunset and
the lowest occurring from midnight to pre-dawn hours
(Shoko, 2014). Variability in the daily peak concentrations
of these critical factors induces various degrees of
exposure to lethal and sublethal effect (Siddiqui, 1991).
Parameters such as turbidity, electrical conductivity and
salinity are not of major concerns in inland aquaculture
settings since their effect on fish health is relatively minimal
(Devi, 2013). High stocking density of fish in ponds usually
exacerbates problems with water quality and sediment
deterioration (Bhatnagar et al., 2004). Wastes generated
by aquaculture activity (faecal matter and unconsumed
feed) first settle at the bottom, and as a consequence,
organic waste and metabolite of degraded organic matter
are accumulated in sediment and water (Fynn, 2015). Part
of the waste is flushed out of the ponds immediately or
later, after the organic matter has been degraded (Boyd,
1990). Low dissolved oxygen level is the major limiting
water quality variable in aquaculture systems as it has
implications for fish survival, feed conversion efficiencies
and resistance to infection and diseases (Boyd, 1995). A
critically low dissolved oxygen level occurs in ponds
particularly when algal blooms die-off and subsequent
decomposition of algal species can elevate ammonia
concentrations and reduce DO leading to stress or
mortality in aquaculture ponds (Parven et al., 2013). Low
dissolved oxygen levels can reduce growth, feeding and
molting frequency (Boyd, 1990). Another major effect of
aquaculture production is a high degree of variability in the
concentration of dissolved nitrates, nitrites and ammonia
(Schwartz, 1994). The environmental conditions that
create high ammonia concentrations may also cause
increase in nitrite concentration. Both ammonia and nitrite
can be directly toxic to culture organisms or can induce
sub lethal stress in culture populations that results in
lowered resistance to diseases (Boyd, 1995).
Sunyani is considered the aquaculture hub of Ghana due
to the high numbers of commercial fish farms (MoFAD,
2015). However, there is poor management of water
quality due to lack of understanding of pond ecosystem
dynamics and the complexity of water quality processes
that affect aquaculture productivity. Despite the high
density of ponds, production is relatively low (Rurangwa,
2015). Production outputs from most farms are lower that
are expected from the size of inputs into these farms which
often leads to low profitability and economic losses for
many farmers. Farmers commonly speculate that viability
of fingerlings and poor feed quality may be responsible for
the low fish productivity even though such assertions are
yet to be empirically ascertained. Yet still, the role of water
quality in fish production is overlooked. In view of the
extremely limited scientific data, a comprehensive
assessment of water quality in aquaculture ponds was
required to provide insight into factors controlling water
quality dynamics in aquaculture ponds. The aim of this
study therefore, was to assess the interaction of
hydrographic and production factors on water quality
dynamics in ponds reared with two common culture
species, Oreochromis niloticus (Nile tilapia) and Clarias
gariepinus (African catfish). The scope of the current study
will serve as an important baseline for understanding water
quality dynamics and consequently shape future research
directions.
3. Understanding Water Quality Dynamics in Aquaculture Ponds in Sunyani, Ghana: Insights from Partial Least Squares (PLS) - Path Modeling
J. Fish. Aquacul. Res. 030
Figure 1: Map of study area showing location of sampled ponds
MATERIALS AND METHODS
The Sunyani Municipality is one of the twenty-seven
districts in the Brong Ahafo Region. It is regarded as the
hub of aquaculture production in Ghana due to the
presence of high numbers of active and inactive ponds
(MoFAD, 2015). It is located at the heart of the Brong
Ahafo Region between latitude N 070 20'47'' and longitude
W 0020 17' 06'' and covers a total land area of 506.7km2.
Fish species commonly cultured are the Nile tilapia
Oreochromis niloticus and the catfish Clarias gariepinus.
Oreochromis niloticus however accounts for the bulk of
production. Eleven randomly selected commercial fish
ponds representing 15 % of the total number of ponds
within the study area were investigated. The study ponds
are Berlin Top (BT), Abesim 1(AB1) Abesim 3 (AB3), New
Dormaa 1(ND1), ND1A, New Dormaa 2 (ND2), ND3,
Seventh Day Adventist (SDA), Magazine (MG) and
Dumasua (DS) (Table 1). Newly stocked commercial fish
ponds ranging from 7-21 days were selected in order to
capture the full range of water quality dynamics through
one full production cycle. Out of the selected fish ponds,
three contained catfish, seven tilapia-cultured ponds and
one mixed culture. Sampling usually took place from 6 am
to 2pm on each day. Hydrographic measurements of pond
area (square meters) was done only once but other related
variables such as pond depth (meters) and water quality
parameters were carried out at monthly intervals from
October 2017 to March 2018. This sampling period
marked the mid secondary rainfall period to the end of the
dry season. Production input variables measured included
stocking density, stock age, feed type and feeding
frequency.
Table 1: Coordinates of selected fish ponds in Sunyani
NORTH WEST
SITE
NAME
Deg Min Sec Deg Min Sec ELV
BT 7 20 33.2 2 21 32.9 296
ND1 7 20 48.4 2 18 13.8 297.5
NDI(A) 7 20 47 2 17 28.6 298.8
ND3 7 20 49 2 17 6.6 293.7
AB3 7 20 7.3 2 17 54.9 262.9
AB1 7 16 56.8 2 18 13.4 261.8
MG 7 19 43.2 2 18 36.8 274.6
SDA 7 20 32 2 20 44.5 314
DS 7 23 23.1 2 22 8.5 307
To determine water quality, a multiparameter probe
HANNA H19829 (HANNA Instruments) was used to make
in situ measurements of temperature, pH, dissolved
oxygen, salinity, Total Dissolved Solids (TDS) and
conductivity. Ammonia, nitrite and phosphate were
analyzed on-site with Hydrotest Kit H7100 (Trace 2 O) and
in the laboratory with UV Spectrophotometer UV-1800
240V IVDD (Shimadzu Corporation) following standard
protocols. Water colour was visually assessed whilst water
transparency was estimated using Secchi disc
measurements.
Data Analysis
Summary statistics such as standard deviation, mean and
co-efficient of variation were determined. The Partial Least
Squares - Path Model (PLS-PM) was adopted for this
study and used to examine the relationship among
hydrographic factors, production input and water quality
4. Understanding Water Quality Dynamics in Aquaculture Ponds in Sunyani, Ghana: Insights from Partial Least Squares (PLS) - Path Modeling
Otoo et al. 031
variables based on multiple regressions multivariate
statistics. For the PLS-PM analysis, the data was classified
into input (latent) and output (manifest) variables. Latent
variables comprised hydrographic and production input
parameters, whereas water quality parameters constituted
manifest variables. The PLS-PM measures the size of
correlations between different sets of direct and indirect
variables classified as the latent and manifest variables. It
includes a qualitative theorized path and quantitatively
measured actual path yielding estimates of the magnitude
and statistical significance of hypothesized and actual
causal relationships between hydrographic, production
and water quality variables. The statistical levels of
significance for the PLS-PM were set at p < 0.05 and p <
0.01 probability levels.
Model specification of PLS-PM
Partial Least Squares (PLS) methods are analytical tools
with algorithmic origins aimed at solving models in a
practical way (Sanchez, 2013). The Path model (Figure 2)
consists of two sub-models namely, the structural or inner
model and the measurement or outer model. While the
inner model is concerned with the relationships between
the latent variables (represented by spheres), the outer
model shows relationships of a latent variable with its block
of manifest variables (represented by rectangles).
Inner Model
The first aspect of the inner model is to treat all structural
relationships as linear relationships as shown in equation
(1).
0j ji i j
i j
LV LV error
→
= + + (1)
Where, the subscript i of LVi refers to all the latent variables
that are supposed to predict LVj. The coefficients ji are
the path coefficients and they represent the strength and
direction of the relations between the response LVj and the
predictors LVi. 0 is the intercept term, and the errorj term
accounts for the residuals. It must also be noted that the
paths formed by the arrows of the inner model cannot form
a loop.
Outer Model
Reflective mode is the most common type of
measurement, where the latent variable is considered as
the cause of the manifest variables. Similar to the inner
model, the outer model relationships are also considered
to be linear as shown in equation (2).
Figure 2. Conceptualized Path Model for latent
(production and hydrographic) variables and manifest
(water quality) variables
0jk jk jk j jkX LV error = + + (2)
Where, the coefficients jk are called loadings; 0 jk is the
intercept term, jkX is the response variable, and the
jkerror terms account for the residuals.
Data analysis was done in R (R Core Team, 2014; Rstudio
Team, 2016) using the package PLS-PM (Sanchez, 2013).
RESULTS
Variation in hydrographic, production and water
quality parameters
Pond size represented by both pond area and pond depth
varied widely across the studied ponds but highest
variation was recorded in tilapia ponds (Table 2). Mean
pond area for both catfish and tilapia ponds were 307.71 ±
216.59 m-2 ranging from 19.52 -722.70 m2 implying wide
variation in the size and depth of commercial ponds used
for culture purposes. Mean pond area was 286.6 ± 19.84
m-2 and 328.8 ± 251.3 m-2 for catfish and tilapia ponds
respectively. The size of ponds used for tilapia culture was
15 % larger than catfish ponds. Depth of fish ponds were
exceptionally shallow across most catfish and tilapia
ponds and less variable, differing by less than 10 %.
Mean pond depth was 0.49 ± 0.16 m ranging between 0.09
- 0.86 m (Table 2). Thus, the average volume of ponds was
approx. 150 m-3, holding average stocking densities of
2125 individuals for the two types of culture ponds.
Variability in stocking density across both pond types was
exceptionally high at 2125 ± 2778 individuals with a
percentage difference of 96 % between upper and lower
limits of stocking density. Mean stocking densities in
catfish and tilapia ponds were 2761 ± 1820 and 2142 ±
3077 individuals respectively. Maximum stocking density
in tilapia ponds was 10,000 compared with the relatively
low 4567 recorded in catfish ponds. Production inputs
variables measured were stocking density, feed type and
feeding frequency. Three types of culture feed were
identified in the study; these are formulated feed Raanan,
local feed and wheat bran. Raanan is a commercially
5. Understanding Water Quality Dynamics in Aquaculture Ponds in Sunyani, Ghana: Insights from Partial Least Squares (PLS) - Path Modeling
J. Fish. Aquacul. Res. 032
formulated feed whereas local feed and wheat bran are
feed formulations prepared by fish farmers without
proximate analysis of nutritional content of the feed.
Raanan was the dominant feed type fed to culture species.
Feeding frequency which is a measure of the daily feeding
rate was 2.09 ± 0.29 with a range of 2.00 – 3.00.
Table 2: Mean and standard deviation of water quality
variables in catfish and tilapia ponds. Ranges are given in
brackets
Variable Catfish pond Tilapia pond
DO (mgL-1) 2.70 ± 0.22
(2.40 - 3.03)
2.978 ±1.070
(2.4-7.4)
pH 7.59 ± 0.83
(6.43 - 8.79)
7.511 ± 0.254
(5.62-8.9)
Salinity (psu) 0.11 ± 0.04
(0.06 - 0.22)
0.111 ± 0.074
(0.03-0.4)
TDS (mgL-1) 117. 4 ± 48.83
(61.0 – 235.0)
105.23 ± 57.34
(33.0-239.0)
Cond. (µS/cm) 241.5 ± 96.47
(129.0 - 470.0)
241.8 ±185.432
(495-74)
Temp. (o C) 27.219 ±1.51
(25.77 - 30.8)
27.83 ± 1.56
NH3 (mgL-1) 0.306 ±0.328
(0.04 - 1.06)
0.206 ± 0.395
(0.025-1.00)
PO4
2- (mgL-1) 0.246±0.195
(0.04 - 0.50)
0.298 ± 0.254
(0.05-1)
Transparency (m) 0.106 ± 0.050 0.172 ± 0.324
(0.01-2.13)
Pond water colour Green Brown
Pond area (m2) 286.6 ± 19.84
(271.4 - 307.8)
328.776 ± 251.324
(19.52-722.7)
Pond water depth
(m)
0.524 ± 0.230
(0.086 - 0.86)
0.486 ± 0.158
(0.22-0.85)
NO2
- (mgL-1) 0.103 ± 0.033
(0.08 - 0.15)
0.236 ± 0.303
(0.08-1)
Stocking density 0.486 ± 0.158
(1035 - 4567)
2761.0 ± 1819.61
(200 – 10000)
Alkalinity (mgL-1) 5.00 ± 0.23 5.00 ± 0.23
Hardness (mgL-1) 2.00 ± 0.01 2.00 ± 0.01
The water quality environment in both ponds showed
remarkable similarities in the parameters measured (Table
2). Generally, with the exception of conductivity and TDS,
all water quality parameters fluctuated little with stable
levels throughout the period. Levels of pH, salinity,
electrical conductivity, temperature, phosphate and
turbidity were uniform across both ponds. Significant
variations were found between the ponds in respect of
dissolved oxygen and nitrites but higher concentrations
were observed in tilapia ponds. By contrast, catfish ponds
had elevated TDS (117 ± 48.8 mgL-1) and high ammonia
concentrations (0.306 + 0.328 mgL-1). High variability in
nitrite and conductivity was found in tilapia ponds.
Variation in salinity of the ponds were the lowest among all
the parameters measured. The difference between high
and low salinity levels was 74%. Variations in TDS were
also significant with a mean value of 107.07 ± 53.52mgL-1
and a range of 33.00-239.00 (Table 2).
Temporal trends in water quality conditions
Catfish ponds
Ponds containing catfish were BT, ND1b and ND3 (Fig 3a
and b). Eight water quality parameters were monitored
seasonally to determine seasonal fluctuations in
environmental conditions affecting growth and
development of culture species. Common patterns were
not apparent among the eight parameters measured in the
culture ponds. Temperature and ammonia showed similar
seasonal variations with a maximum in January at site BT.
Salinity, TDS and conductivity declined sharply at ND3
even though consistently similar patterns had existed
throughout the study period. Nitrite levels at BT and ND1
were consistently low and stable with little fluctuations
throughout the period but declined progressively at ND1
from the onset of the study to the end of sampling.
Phosphate concentrations showed mixed patterns across
sites. Peaks in phosphates occurred in different months in
the three ponds. pH increased at all sites, reached a peak
in December and declined in February. Dissolved oxygen
concentrations showed a consistent rise throughout the
study period reaching a maximum at the end of sampling
in February. The patterns of variation in the amount of
dissolved oxygen in the ponds were similar throughout the
study. Maximum and minimum dissolved oxygen
concentrations were 2.4mgL-1
and 3.03 mgL-1
recorded at
ND1b and BT respectively. Differences in seasonal
characteristics among the measured parameters were
observed. During the dry season, ammonia, phosphate
and DO increased while pH declined and vice versa. The
pH of the ponds was characterized as weakly acidic to
alkaline based on the observed range of values from 6.43
and 8.79. Variation in pH was not significant over the
seasons across ponds (p > 0.05). (Fig 3a).
6. Understanding Water Quality Dynamics in Aquaculture Ponds in Sunyani, Ghana: Insights from Partial Least Squares (PLS) - Path Modeling
Otoo et al. 033
Figure 3a: Monthly pH, phosphate (mgL-1), ammonia (mgL-1), dissolved oxygen (mgL-1), nitrate (mgL-1) and conductivity
(µS/cm) levels in catfish ponds
7. Understanding Water Quality Dynamics in Aquaculture Ponds in Sunyani, Ghana: Insights from Partial Least Squares (PLS) - Path Modeling
J. Fish. Aquacul. Res. 034
Figure 3b: Monthly salinity (psu), total dissolved solids (mgL-1) and temperature (0C) levels in catfish ponds.
Tilapia ponds
Ammonia levels at all sites followed the same pattern with
peak concentrations of 2.157 mgL-1 occurring at site AB3
in February (Fig. 4a). Lowest ammonia concentrations of
0.025 mgL-1 were recorded at AB1 in October during the
secondary rainfall period of the year (Fig. 4a). pH
increased from October to December and remained high
at all sites till the end of the study in February. Salinity,
TDS and conductivity showed similar temporal patterns
comparable with observations made in the catfish ponds
(Fig. 4b). Phosphate levels varied from site to site
throughout the study with the least value of 0.05 mgL-1
recorded at site-SDA in October and the highest value of
1.2 mgL-1 at site DS in November (Fig. 4a). Maximum
concentrations of ammonia occurred in January similar to
catfish ponds. Except at sites ND1, ND2 and SDA, nitrite
concentrations were low throughout the study. DO levels
were higher in November but there was a gradual
decrease from December to February. This pattern of DO
sharply contrasts the situation observed in catfish ponds
where DO concentrations increased progressively over the
study period. Temperature conditions were variable
among the ponds fluctuating between 27.83 and 31.60 0 C
with a mean of 25.04 ± 1.580C. The highest water
temperature of 31.6 0 C was recorded at site-ND2 in
January. Dissolved oxygen levels of 7.4 mgL-1 recorded at
site DS in February during the dry season was the highest
recorded but lowest DO of 2.4 mgL-1 occurred in October
at ND1. pH conditions fluctuated between moderate
alkaline of 8.9 in December to weakly acidic levels of 5.6
in October. Overall, mean pH conditions showed neutral
conditions the mean of 7.5 ± 0.9 measured. TDS, salinity
and conductivity showed mixed patterns increasing and
decreasing in different months.
8. Understanding Water Quality Dynamics in Aquaculture Ponds in Sunyani, Ghana: Insights from Partial Least Squares (PLS) - Path Modeling
Otoo et al. 035
Figure 4a: Monthly pH, phosphate (mgL-1), ammonia (mgL-1), dissolved oxygen (mgL-1), nitrate (mgL-1) and conductivity
(µS/cm) levels in Tilapia ponds
9. Understanding Water Quality Dynamics in Aquaculture Ponds in Sunyani, Ghana: Insights from Partial Least Squares (PLS) - Path Modeling
J. Fish. Aquacul. Res. 036
Figure 4b: Monthly salinity (psu), total dissolved solids (mgL-1) and temperature (0C) levels in tilapia ponds
Analysis of variance (ANOVA) and correlations among
cluster variables
Relationship between hydrographic and water quality
variables
Hydrographic factors had little effect on general water
quality as shown by the weak correlations and the lack of
statistical significance (p > 0.05) (Table 3). Most of the
water quality parameters showed a weak negative
correlation with pond area and pond depth with few
showing weak positive correlations. Correlation of pond
area and conductivity showed the weakest relationship
among all the negatively correlated variables with a
correlation coefficient (R2 = -0.187, p < 0.05, n = 55) whiles
correlation of pond area and nitrite showed a weak
negative correlation. Correlation of pond depth with pH
was low and negatively correlated among all the variables
with a value of (R2 = -0.349, p < 0.05, n =55) while the
relationship between pond depth and temperature showed
a weak positive correlation (R2 = 0.103, p < 0.05, n =55)
(Table 3).
Table 3: Correlation coefficients and significance of statistical relationships among hydrographic factors, production input
and water quality variables
Variable Nitrate Ammonia Phosphate pH DO Conductivity Temp TDS Salinity Transparency
Pond Area -0.045 -0.053 -0.093 0.010 0.307 -0.186 0.369 -0.164 0.057 -0.055
Pond Depth 0.131 -0.263 -0.012 -0.349 -0.164 -0.035 0.103 -0.018 -0.101 -0.071
Stock Density -0.256 -0.012 -0.088 0.008 0.078 0.308 -0.010 0.348 0.230 0.036
Mortality -0.065 -0.084 -0.168 -0.045 0.026 0.064 -0.098 0.061 0.017 -0.050
Feed Type -0.091 -0.117 0.252 -0.046 0.007 -0.399 -0.208 -0.377 -0.378 -0.056
Feeding Freq. 0.075 -0.079 -0.074 -0.035 -0.151 0.531* -0.158 0.517* 0.366 -0.065
Stock Age -0.407 0.449* 0.257 0.616* 0.253 0.025 -0.219 0.039 0.083 -0.168
* Correlation is significant at the p < 0.05 probability level
Table 4: Relationship between feed type and fish production variables
Fish production
indicators
Group means Overall
mean
F-value P-value
Raanan Local Feed Wheat Bran
Stock density 1705.800a 3745.000b 200.000c 2125.055 4.719 0.013
Mortality 3.428 0.067 0.000 2.200 0.386 0.682
Feeding frequency 2.142 2.000 2.000 2.091 1.576 0.217
Stock age 103.714 105.067 90.000 102.836 0.184 0.832
Note: Means in the same row that do not share a common alphabet are significantly different at p <0.05
10. Understanding Water Quality Dynamics in Aquaculture Ponds in Sunyani, Ghana: Insights from Partial Least Squares (PLS) - Path Modeling
Otoo et al. 037
Relationship among production, feed type and water
quality variables
Most of the correlations between production factors and
water quality parameters were negatively correlated with
each other (Table 3). Among production factors, stocking
density, feeding frequency and stock age influenced
critical water quality parameters such as ammonia, pH and
dissolved oxygen. The variation in stock age accounted for
significant variations in ammonia concentrations (R2 =
0.45, p < 0.05, n = 55), pH and dissolved oxygen.
Correlation between stock age and pH showed a strong
positive relationship of R2 = 0.617, p < 0.05, n = 55 while
the relationship between stock age and ammonia had a
relatively weak but positive correlation of R2 = 0.449.
Feeding frequency determined significant variations in
conductivity, TDS and salinity with correlation coefficients
indicating that 50 % of variations in these water quality
parameters could be attributed to feeding rates of the
culture species in the ponds. The correlations between fish
production variables and water quality indicators show
varied relationships (Table 3). The results of the statistical
analysis between feed type and fish production indicators
showed that farms that had significantly high stock density
utilized local feed than farms that use Raanan or wheat
bran (Table 4). There was however no significant
difference in mortality, feeding frequency and stock age
across farms that used local feed, Raanan or wheat bran.
The ANOVA results from the analysis of the relationship
between feed type and water quality showed significantly
higher phosphate concentrations in ponds that use wheat
bran than ponds fed with Raanan and local feed (Table 5).
On the other hand, farms that use Raanan recorded
significantly higher conductivity, TDS, and salinity values
than farms that use local feed or wheat Bran. There was
however no significant difference in nitrite, ammonia, pH,
dissolved oxygen, temperature and transparency across
the farms irrespective of the feed type administered (Table
5).
Table 5: Results of the ANOVA showing relationship between feed type and water quality variables
Water quality indicators Group means Overall mean F-value P-value
Raanan Local Feed Wheat Bran
Nitrate 0.251 0.273 0.108 0.244 0.641 0.531
Ammonia 0.310 0.130 0.248 0.256 0.780 0.464
Phosphate 0.257a 0.245a 0.544b 0.280 3.901 0.026*
pH 7.553 7.506 7.406 7.527 0.060 0.942
Dissolved Oxygen 2.798 2.701 2.912 2.782 1.027 0.365
Conductivity 250.171a 188.600b 114.800c 221.073 4.967 0.011*
Temperature 28.098 27.423 27.326 27.844 1.332 0.273
TDS 120.314a 93.400b 55.400c 107.073 4.378 0.017*
Salinity 0.127a 0.088b 0.050b 0.109 4.357 0.018*
Transparency 0.178 0.125 0.160 0.162 0.179 0.837
Correlation matrix of water quality parameters
Covariation of the ten water quality variables assessed
showed predominantly negative correlations lacking any
meaningful statistical significance (Table 6). pH was
positively and significantly correlated with ammonia and
phosphate explaining 42 % and 30 % of variations among
those parameters. Temperature did not covary
significantly with ammonia concentrations and levels of
dissolved oxygen. Nitrite and phosphate were negatively
correlated but the strength of relationship was weak but
significant (R2 = -0.278, p < 0.05, n =55). TDS and
conductivity were highly correlated with each other.
Conductivity showed a strong positive correlation with TDS
(R2 = 0.9929, p < 0.05, n =55) and a moderate positive
correlation with salinity (R2 = 0.6657, p < 0.05, n =55)
explaining 99 % and 66 % respectively for the variations in
water quality (Table 6). Salinity was moderately correlated
with TDS (R2 = 0.6689, p < 0.05, n =55) accounting for
66% of the variations in water quality (Table 6). Other
water quality parameters showed weak and insignificant
correlations with each other.
Table 6: Covariation among water quality variables at p < 0.05 and p < 0.01 significant levels
Variables Nitrate Ammonia Phosphate pH DO Conductivity Temp TDS Salinity Transparency
Nitrate 1
Ammonia -0.251* 1
Phosphate -0.278** 0.063 1
pH -0.331** 0.415** 0.300** 1
DO 0.018 0.032 -0.110 -0.027 1
Conductivity -0.222 0.192 -0.159 0.092 -0.211 1
Temp 0.223 -0.089 -0.240* -0.298 0.191 -0.247** 1
TDS -0.233* 0.208 -0.158 0.108 -0.182 0.992** -0.254* 1
Salinity -0.243* 0.169 -0.159 0.143 -0.079 0.665** 0.061 0.668** 1
Transparency -0.037 0.006 -0.103 -0.155 -0.175 0.058 0.002 0.045 0.184 1
** Correlation is significant at the 0.05 level * Correlation is significant at the 0.01 level
11. Understanding Water Quality Dynamics in Aquaculture Ponds in Sunyani, Ghana: Insights from Partial Least Squares (PLS) - Path Modeling
J. Fish. Aquacul. Res. 038
Model Outputs from Path Analysis
Hydrographic and production factors constitute latent
variables that yield inputs into water quality manifest
variables. From the hypothesized path, hydrographic and
production factors each exert direct effects on water
quality but hydrographic factors can also influence water
quality indirectly through the structure of the production
system and its dynamics. The measured path (actual path)
gives estimates of the actual size of correlations between
latent and manifest variables. Hydrographic and
production factors were both negatively correlated with
water quality variables through direct and indirect effects.
Production factors had a dominant effect on water quality
(R2 = -0.821, p < 0.05, n = 55) explaining 82% of the
variations in water quality of the ponds investigated.
Production was inversely correlated with water quality
showing that an increase in production inputs reduced
water quality significantly. Direct hydrographic effects on
water quality were minimal as they could not explain a
large proportion of the variation in the water quality of the
ponds (R2 =- 0.1231, p < 0.05, n =55), but direct effects of
hydrography on production dynamics were large and
significant but also characterized by an inverse
relationship (R2 =-0.613, p < 0.05, n =55). Variation in
hydrographic factors accounted for 61 % of the variability
in production factors. (Fig.5).
Figure 5: Outputs from the actual path showing
correlations coefficients between groups of latent and
manifest variables
Model fit statistics
Table 7 shows the general fit of the canonical correlation
model reporting Pillais, Hotellings, Wilks, and Roys
multivariate criteria. We observe that all these values are
significant with p < 0.05. The canonical correlation
coefficients and the eigenvalues of the canonical roots
show that the first canonical correlation coefficient is 0.813
with an explained correlation variance of 61.01% and an
eigenvalue of 1.953, thus, indicating generally that fish
production factors are positively correlated with water
quality variables (Table 8). The significance of each of the
roots was tested. Among the four possible roots, only the
first root is significant with p < 0.05. Hence, we interpret
coefficients corresponding to only the first canonical
function. The unstandardized canonical coefficients are
interpreted in a manner similar to the coefficients in linear
regression and can be used to calculate the canonical
scores. However, interpreting the standardized canonical
coefficients is much easier as shown that stock age had
the strongest influence on the first canonical root (Table 8).
pH had the strongest influence on the first canonical
variate among the covariates while transparency had the
least influence.
Table 7: General fit of the canonical correlation model
Pillais 1.39897 2.36656 0.000
Hotellings 3.202 3.162 0.000
Wilks 0.132 2.772 0.000
Roys 0.661
Table 8: Eigenvalues and canonical correlations
Root
No.
Eigen
value
Pct. Cum. Pct. Canon.
Cor.
Sq.
Cor
1 1.953 61.007 61.007 0.813 0.661
2 0.956 29.865 90.873 0.699 0.488
3 0.214 6.709 97.582 0.420 0.176
4 0.077 2.417 100.000 0.268 0.071
Table 9: Canonical coefficients for multivariates
Variable Canonical Function I Canonical Function II
Standardized
Coefficients
Unstandardized
Coefficients
Standardized
Coefficients
Unstandardized
Coefficients
Nitrate -0.380 -1.327 0.194 0.678
Ammonia 0.326 0.699 0.207 0.445
Phosphate -0.020 -0.087 0.001 0.005
pH 0.500 0.546 -0.172 -0.188
Dissolved Oxygen 0.331 1.079 -0.202 -0.658
Conductivity 0.026 0.002 1.497 0.013
Temperature -0.075 -0.048 0.032 0.021
TDS -0.447 -0.008 -2.348 -0.043
Salinity -0.045 -0.682 -0.064 -0.959
Transparency -0.013 -0.049 0.096 0.342
12. Understanding Water Quality Dynamics in Aquaculture Ponds in Sunyani, Ghana: Insights from Partial Least Squares (PLS) - Path Modeling
Otoo et al. 039
Hydrographic, Production and Water Quality Loadings
Pond depth showed a very strong negative correlation with
hydrographic loadings (R2 = -0.929, p < 0.05, n =55) but
pond area had a weak effect, and accounted for 92% of
the collective effect of hydrographic loadings (Fig. 6).
Stock age had the largest influence on production, exerting
a negative but strong correlation with production loadings
(R2 =-0.921, p < 0.05, n =55), and explaining 92% of the
variations in production loadings (Fig. 6). Ammonia, pH
and nitrite produced strong effects on water quality. Nitrite
had a moderately negative correlation with water quality
(R2 =-0.592, p < 0.05, n = 55) while ammonia was positive
and highly correlated with water quality (R2 =0.682, p <
0.05, n =55). Nitrite and ammonia thus explained 59 %
and 68 % of the variation in water quality loadings
respectively (Fig. 6). Effect of other variables on water
quality was significantly low.
Figure 6: Loadings for various constructs
DISCUSSION
The results obtained from the study indicate there are
predominantly large defects in the water quality of
commercial fish ponds used to rear culture species. A
prevalence of suboptimal conditions under which fish are
commercially cultured for consumption implies that rate of
fish production may be hampered by the stressful growth
environment in which the fish live. Both catfish and tilapia
ponds were characterized by low average DO (< 4 mgL-1),
high temperatures and elevated concentrations of
ammonia and phosphates. Algal blooms occurred in most
of the ponds and persisted through the entire production
cycle. The high levels of ammonia and phosphates
combined with high temperatures may accelerate
biological uptake of these dissolved limiting nutrients
required for photosynthetic activity. Nitrogen and
phosphorus compounds are critical for algal growth and
may explain the prevalence of algal blooms in most ponds
investigated. pH ranged between moderate alkalinity to
low acidity. The low fluctuations in pH suggests good
buffering capacity of the pond water despite sharp diurnal
changes in carbon dioxide concentrations arising from
photosynthesis and respiration processes which regulate
the pH and its effect on ammonia dynamics. Detrimental
effects of the poor water quality on fish health may be
reflected in increased stress and susceptibility to diseases,
infections and mortality which ultimately affects the
efficient and profitable production of fish (Isyiagi et al.,
2009). This is confirmed by the high mortality of catfish
observed in ponds with algal blooms, and may be evident
of low amounts of DO during the late night to early morning
periods where respiratory activities of organisms consume
the available DO and renders DO concentrations below
tolerable limits.
Pond area and pond depth both constitute important
hydrographic factors that influence the physical properties
of pond ecosystem.. The studied ponds were generally of
small sizes, even though there is no general restriction on
the size of ponds used in aquaculture production. On the
basis of the fact that the ponds are used for commercial
purposes rather than subsistence, they can be
characterized as small compared with ponds in other
geographical regions used primarily for commercial
production. The choice of pond size is entirely based on
the discretion of the farmer, but is mainly influenced by
expected production outputs of the farm within the
economic and resource constraints of the farmer’s planned
operations.
Extremely high stocking rates were found which exceeded
the carrying capacities of the small ponds overstocked by
200 % on average above recommended stocking rates
(Gindaba and Mulugeta, 2017). For example, a 217 m2
earthen pond was stocked with 4567 catfish far in excess
of the recommended stocking rates of 8-9 individuals/m2
for catfish and 3-5 individuals/m2 for tilapia respectively
(Isyiagi et al., 2009). Pond water depths were remarkably
shallow in the aquaculture ponds, a pervasive
phenomenon which can be considered as a key
management decision that characterizes the industry. The
reason given by the farmers for maintaining such high
production intensities in extremely shallow ponds is to
ease harvesting, without cognizance of the serious and
deleterious consequences of combining shallow water
depths and high tropical temperatures with high stocking
densities on water quality in the ponds. The average pond
water depth of 0.52 ± 0.23 m for catfish and 0.49 ± 0.16 m
for tilapia contrasts the recommended depths for grow-out
aquaculture production of 1.0 – 1.5 m or 1.0 – 2.0 m (Fynn,
2015). This phenomenon indicates that aquaculture
farmers and perhaps water quality managers have a poor
understanding of the importance of greater pond water
volumes on dilution of potentially toxic concentrations of
dissolved constituents such as ammonia, nitrite, carbon
dioxide and hydrogen sulphide. Furthermore, high
temperature conditions prevailing in the tropics does not
favour water retention in the shallow ponds due to the rapid
water loss from high evaporation rates. Deeper ponds of
1-2 m, compliant with standard pond metrics will among
other benefits hold larger volumes, increase dilution of
13. Understanding Water Quality Dynamics in Aquaculture Ponds in Sunyani, Ghana: Insights from Partial Least Squares (PLS) - Path Modeling
J. Fish. Aquacul. Res. 040
toxic substances and thus minimize toxicity, stabilize pond
against daily temperature extremes, reduce wind-driven
diffusion of ammonia and hydrogen sulphide from pond
sediments into the overlying water column and improve
water quality.
The study also revealed that management decisions
regarding production inputs were the primary causes of
water quality in the aquaculture ponds. Stocking densities
were high, relative to pond size as explained in the
hydrographic context of the water quality dynamics. High
stocking densities necessitates high feeding rates which
leads to excretion of large amounts of metabolic waste
such as ammonia by fish. The primary source of ammonia
in waste excreted by fish is dietary protein, which is
metabolized to build muscle tissue and produce energy
(Hargreaves and Tucker, 2004). Ammonia may also be
produced from decomposition of organic matter such as
dead algae and feed waste from the pond sediment. Rapid
diffusion of ammonia from the sediment into the overlying
water column may be facilitated by the shallow pond water
depth, high temperatures and wind-generated
disturbances to the pond bottom (Delince, 1992). High
stocking densities also lead to elevated respiration rates
and greater consumption of DO and release of toxic
metabolites. The low average DO concentrations (< 4 mgL-
1) suggest that fish are consistently living in an oxygen-
stressed environment. Low DO concentration is inimical to
fish as it suppresses fish feeding ability, increases
susceptibility to infection and diseases and limits the
efficiency of feed conversion (El- Sayed, 2002). Reduced
feeding rate due to oxygen stress results in deposition of
large quantities of feed waste at the pond bottom through
rapid sedimentation over the shallow water column. Thus
water quality may be impaired through decomposition of
organic matter and release of toxic by-products. .
In terms of the contribution of feed type and its nutritional
composition on water quality, three main feed types were
found to be fed to fish; raanan, wheat bran and local feed.
Raanan is a commercially produced, formulated, pelleted
fish feed whose nutrient composition is known. Pelleted
feeds have high hydrostability, flotation decreased settling
rateof uneaten feed to the pond bottom (Sørensen, 2012).
This type of feed thus contributes little to sediment
decomposition of organic matter and production of
ammonia from feed waste. However, Raanan was
positively and significantly correlated with conductivity,
TDS and salinity in the ponds but values were all within the
acceptable limits of pond water quality standards. The
study therefore found no evidence of water quality
deficiencies resulting from feeding fish with Raanan. The
second type of feed, wheat bran is a composite feed
prepared by the farmers themselves and contains wheat,
oyster shells, palm kernel, soybean (rich source of
protein). It has lower hydrostability properties and rapidly
settles to the pond bottom. Wheat bran was positively and
significantly correlated with high phosphates in the ponds
(p < 0.05) in both tilapia and catfish ponds and could
possibly explain the persistent algal blooms in the fish
ponds. Algae utilize phosphate as a nutrient source in the
production of organic matter, and as a limiting nutrient in
algal growth has a threshold concentration of 0.01 PmgL-1
(Reynolds 2007). The excessive phosphate
concentrations could account for the dense algal growths
in the ponds. Phosphates may originate from agricultural
fields in the watershed of the ponds investigated and may
be carried by run-off into surface water bodies used as
source water for the ponds. Phosphates are known to
contribute prominently to eutrophication in aquatic
systems due to the important role they play in algal growth
(Hussein, 2012). The high algal biomass may result in
high quantities of dead sedimenting algae to the pond
bottom, decomposing and contributing to water quality
deterioration through the production of toxic metabolites
which are released back into the water column. The wheat
bran may however contribute indirectly to ammonia
production through feeding and excretion of fish. The third
type of feed is the local feed which is also prepared locally
by farmers with varying composition of different feed
sources. It is usually a mixture between proportions of
Raanan and other nutrient sources such as soybean and
oyster shells. These feeds do not undergo heat treatment
and pelletization and therefore like wheat bran, has lower
hydrostability. This type of feed was found to have no
negative effect on water quality.
Stock age influenced the concentrations of ammonia, pH
and DO. Rate of excretion of metabolites such as
ammonia, is a direct function of feeding rate and both
processes are known to increase linearly with increasing
body size (Ip et al., 2007). Fish growth increases as
feeding rates increase resulting in the high amounts of
ammonia excreted. Older fishes are also likely to consume
greater amounts of dissolved oxygen to metabolize the
feed ingested which explains the effect of stock age on
variations in ammonia. pH also increased with stock age
as ammonia production increased. The utilization of
ammonia by algae as a nutrient during photosynthesis
directly elevates pH of pond water when consumption of
large amounts of carbon dioxide leads to an increase in pH
typically in the afternoon. Growing fishes may respire more
at night thereby increasing the carbon dioxide
concentration, lowering pH and increasing acidity.
The Path Model predicted that production inputs would
dictate water quality in aquaculture ponds, which is in
agreement with the assertions of Boyd and Tucker (1998).
According to the model, 82 % of variation in water quality
is attributed to the production inputs. The actual path gives
estimates of the actual size of correlations between latent
and manifest variables. Even though PLS-Path Model has
its roots in the social sciences, it has gained an
increasingly popular role in empirical research from other
disciplines such as medicine (Berglund et al., 2012),
engineering and sustainability (Hussain et al., 2018), and
14. Understanding Water Quality Dynamics in Aquaculture Ponds in Sunyani, Ghana: Insights from Partial Least Squares (PLS) - Path Modeling
Otoo et al. 041
environmental science (Brewer et al., 2012; Kumar et al.,
2015; Javari, 2015). This is mainly because the technique
imposes little demand on sample sizes, measurement
scales, and residual distributions, unlike other causal
models that involve latent variables. Several metrics have
been provided (Table 8) as an overall summary of the
structural model. The coefficients of determination (R2) of
the endogenous latent variables (Production and Water
Quality) suggest that hydrographic indicators explain
about 38% and 57% of the variance in production and
water quality respectively. The mean redundancy for
production and water quality implies that hydrographic
indicators predict about 7% and 10% of the variability in
production and water quality indicators respectively. The
final measure of quality that was examined is the
goodness-of-fit index. This measure assesses the overall
prediction performance of the model by taking into account
the communality and coefficients of determination. The
goodness-of-fit index (Table 7) suggests that the
prediction power of the fitted Path Model is about 32%
which is quite significant.
Water quality is the most important factor affecting fish
health and performance in aquaculture production
systems (Blancheton et al., 2013). The path model
developed in this study has significant practical
implications for water quality management in aquaculture.
For instance, the model results (Table 7) indicate a direct
negative relationship between hydrographic factors (pond
area and pond depth) and water quality. This negative
relationship implies that water quality in aquaculture ponds
can be enhanced by paying attention to pond area and
pond depth. A bigger pond area and high stocking rates
may result in a decrease in water quality. The model
results also indicate a direct negative relationship between
fish production factors (stock density, mortality, feed type,
feeding frequency and stock age) and water quality, which
means that an increase in stock density, mortality, feeding
frequency and stock age can lead to a decrease in water
quality in aquaculture ponds.
CONCLUSION
The study revealed that aquaculture production of Nile
tilapia and African catfish in Sunyani is characterized by
small, shallow and overstocked culture ponds. The major
water quality problems found were low average DO (< 4
mgL-1), high temperatures, high ammonia, phosphates
and algal blooms, which could retard fish growth and
productivity due to the inhospitable water quality
environment. Reduced pond depth may promote the
release of ammonia from the sediment into the overlying
shallow water column, from excessive feeding rates
arising from the high stocking densities. Levels of
dissolved oxygen was within range but ammonia
concentrations were lethal to fish growth, and most of the
ponds had abnormally dense populations of algae
potentially releasing toxins into the pond with
consequences for fish growth and consumers due to the
risk of bioaccumulation. Production inputs such as feed,
stocking density and feeding frequency had very high
impact on water quality. Standard stocking rates, feeding
rates and construction of deeper ponds, together with
regular monitoring, are recommended to improve water
quality conditions in ponds.
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