Indonesia is lucky to escape the rampage of the shrimp disease EMS because of 2 factors: 1. control of its border to shrimp genetic material, and 2. very hygienic pond bottom maintenance
Indonesia is lucky to escape the rampage of the shrimp disease EMS because of 2 factors: 1. control of its border to shrimp genetic material, and 2. very hygienic pond bottom maintenance
Fish farming traditionally has many drawbacks. But it evolved after the ages to produce huge number of fishes in lesser space with Biofloc technology which has a competitive advantage over the traditional technique.
Current food needs in the world are growing due to population boom and the popularity of fish is drastically improved due to it, whereas the supply of fish becoming stagnant due to pollution, plastic and many factors, etc. To tackle this needs scientists have developed a technique to produce it commercially with less space, in lesser time with a less inorganic food requirement.
FRESHWATER FARMING OF BRACKISHWATER SHRIMP, PENAEUS MONODON (FABRICIUS) WIT...American Research Thoughts
Abstract: Brackish water shrimp (Penaeus monodon) farming expanded rapidly after the technical
viability of this culture system was established and farmers discovered that the high profits derived
from shrimp production could easily offset increased costs associated with this culture. These factors
facilitate the spread of brackish water shrimp farming into freshwater agricultural areas of Purba
Medinipur district of West Bengal that never experience salt water intrusion. The emergence of
brackish water shrimp farming within paddy growing regions of Purba Medinipur district has raised
concerns regarding potential environmental impacts and the suitability of conducting this activity
within highly productive freshwater agricultural areas. In the present study an attempt had been
made to farm the black tiger shrimp, Penaeus monodon in almost freshwater condition with
innovative technologies in 04 earthen tanks each with 0.4 ha water spread area under Contai -III Dev.
Block in Purba Medinipur district in the year 2011 (April to August). The PCR tested P. monodon
seeds (PL15) were stocked in all freshwater earthen tanks after proper acclimatization @
50,000nos/tank. The salinity of the tanks was recorded between 0.0063 ppt to 0.04 ppt. The shrimps
were fed with branded feed and the feeding schedule was based on check-tray method as well as a feed
chart given by the concerned manufacturer.
The early mortality syndrome (EMS) in shrimp has been ravaging production systems, spreading vertically in Asia and horizontally to countries as far away as Mexico since first reported in 2009.
Biofloc fish farming for sustainable aquacultureOrganicaBiotech1
Biofloc technology is an emerging, eco-friendly and cost-effective approach for sustainable fish farming. Earlier, the biofloc system was used as the means to treat wastewater and control fish production.
One of the prevailing shrimp diseases in Asia now is white feces disease which causes tremendous economic loss. This article explains what it is and possible control measures.
Fish farming traditionally has many drawbacks. But it evolved after the ages to produce huge number of fishes in lesser space with Biofloc technology which has a competitive advantage over the traditional technique.
Current food needs in the world are growing due to population boom and the popularity of fish is drastically improved due to it, whereas the supply of fish becoming stagnant due to pollution, plastic and many factors, etc. To tackle this needs scientists have developed a technique to produce it commercially with less space, in lesser time with a less inorganic food requirement.
FRESHWATER FARMING OF BRACKISHWATER SHRIMP, PENAEUS MONODON (FABRICIUS) WIT...American Research Thoughts
Abstract: Brackish water shrimp (Penaeus monodon) farming expanded rapidly after the technical
viability of this culture system was established and farmers discovered that the high profits derived
from shrimp production could easily offset increased costs associated with this culture. These factors
facilitate the spread of brackish water shrimp farming into freshwater agricultural areas of Purba
Medinipur district of West Bengal that never experience salt water intrusion. The emergence of
brackish water shrimp farming within paddy growing regions of Purba Medinipur district has raised
concerns regarding potential environmental impacts and the suitability of conducting this activity
within highly productive freshwater agricultural areas. In the present study an attempt had been
made to farm the black tiger shrimp, Penaeus monodon in almost freshwater condition with
innovative technologies in 04 earthen tanks each with 0.4 ha water spread area under Contai -III Dev.
Block in Purba Medinipur district in the year 2011 (April to August). The PCR tested P. monodon
seeds (PL15) were stocked in all freshwater earthen tanks after proper acclimatization @
50,000nos/tank. The salinity of the tanks was recorded between 0.0063 ppt to 0.04 ppt. The shrimps
were fed with branded feed and the feeding schedule was based on check-tray method as well as a feed
chart given by the concerned manufacturer.
The early mortality syndrome (EMS) in shrimp has been ravaging production systems, spreading vertically in Asia and horizontally to countries as far away as Mexico since first reported in 2009.
Biofloc fish farming for sustainable aquacultureOrganicaBiotech1
Biofloc technology is an emerging, eco-friendly and cost-effective approach for sustainable fish farming. Earlier, the biofloc system was used as the means to treat wastewater and control fish production.
One of the prevailing shrimp diseases in Asia now is white feces disease which causes tremendous economic loss. This article explains what it is and possible control measures.
Meticulous feed monitoring in shrimp farming coupled with understanding of carrying capacity and culture system enables the shrimp farmer to reap handsome profits
Aquaponics require only 5% of the usual water intake for growing Food, Feed, Herbs, Fish and other high-value agri products. It is a revolutionary concept already adopted by UAE by creating one of the largest farms in the world. Interesting reading and great business potential.
A new way of farming! Grow Fish, Grow Vegetables at the same time, saving water, time, space , efforts and all ORGANIC.
Read this presentation to know more about it.
The development of aquafeed production is followed by the growing interest in raw materials which are to be interesting, attractive and valuable, not only in terms of their properties. There is no doubt that algae are one of them. Feeds with the addition of algae are perceived as premium products. This can result from the fact that algae evoke certain associations with healthy food for humans. Animal food with algae must then trigger the same positive associations. Moreover, specially processed algae or feeds with the addition of algae offered by the producers allowed for keeping popular algae-eating freshwater and marine fish.
Productivity of phytoplankton using different organic fertilizers in the glas...AbdullaAlAsif1
The experiment intended to estimate the productivity using different organic fertilizer and to identify the species of phytoplankton in the aquarium tanks. The study was conducted in the laboratory Phytoplankton samples for culture were collected from fisheries experimental pond by using conical-shaped monofilament nylon net (phytoplankton net). Three treatment such as cow dung (T₁), chicken manure (T₂) and control (T₃) were designed. Each treatment had two replications. In case of T₁ and T₂, 10 g of fertilizer was used in each aquarium tank. Sampling of phytoplankton for counting and identification was done every week and 1 litre of water sample was taken from each tank. Phytoplankton sample for identification were preserved by Lugol's solution. Three physicochemical parameters namely water temperature, dissolved oxygen (DO) and pH were measured in every sampling week during the study period. Water quality parameters of the aquarium tank varied with the variation of sampling week. There was no significant difference between water temperature, pH and DO in case of three treatment. The mean water temperature, pH and DO were 21.85±1.95 °C, 8.38±0.23 and 5.55±0.58 mg/l, respectively. The abundance of phytoplankton in T₁, T₂ and T₃ were 25-65, 25-105 and 6-20 individual/l, respectively. The phytoplankton abundance were influenced by different organic fertilizer and noticed higher in number by using chicken manure. Irregular relationship between phytoplankton abundance and water temperature was found. Phytoplankton showed positive relationship with DO. In this study 15 species of phytoplankton were identified under four groups namely Chlorophyta, Cyanophyta, Bacillariophyta and Euglenophyta. Chlorophyta (52%) was the dominant group in the aquarium. The findings of the present study will help to improve the management strategies of water quality, for estimating the productivity of phytoplankton and for the best use of organic fertilizer especially chicken manure.
Aquaculture (less commonly spelled aquaculture), also known as aquafarming, is the farming of fish, crustaceans, molluscs, aquatic plants, algae, and other organisms. Aquaculture involves cultivating freshwater and saltwater populations under controlled conditions, and can be contrasted with commercial fishing, which is the harvesting of wild fish.
Freshwater and coastal aquaculture development can benefit from internal and external experience for preventing environmental damage and for avoiding harmful effects of degradation on aquaculture resources. Strategies to compensate for the loss of aquatic fauna (e.g. due to physical obstructions) are directly linked to important environmental issues, such as the transfer of exotic species, the spread of diseases and loss of genetic diversity, eutrophication, impairment of aesthetic qualities and the disruption of indigenous fish stocks.
There presently, conceptual frameworks for aquatic environment management backed by legal and administrative tools to create or enforce ration systems for water management, land use or fisheries and aquaculture development strengthened by adaptive institutionalization.
Best 10 Economic Importance Of Aquaculture.pdfProjitMondol1
Best 10 Economic Importance Of Aquaculture
Aquaculture
Fisheries and aquaculture make a big contribution to development in the areas of employment. Describing the importance of aquaculture is not an easy task. According to M. Shahbandeh, the number of people who were engaged in fishing and aquaculture amounted to around 40.34 million and 19.27 million respectively worldwide in 2016 and the number has been increasing day by day since 1995. The vast majority of them are from developing countries, working in fish production or fish raising, fish processing, harvesting, and small-scale fish business.
Importance of Aquaculture
Aquaculture; Image: aquaculturealliance.org
Table of Contents
Aquaculture
Aquaculture is the controlled process of rearing, breeding and harvesting of aquatic species, both animals and plants, especially for human consumption, though it is controlled aquatic environments like the oceans, lakes, rivers, ponds, and streams. It’s a similar conception to agriculture, but with fish instead of plants or livestock. It also serves various functions such as food production, restoration of threatened and endangered species populations, wild stock population enhancement, the building of aquariums, and fish cultures, and habitat restoration.
History of Aquaculture
The husbandry of fish is therefore not a new phenomenon. Ancient practices based on the modifications of natural bodies of water or wetlands to entrap young fish in enclosures until harvest have just evolved into more systematic and scientific methods and techniques.
Aquaculture has a long tradition, which is about 4 000 years, and form the beginning of the time man identified the importance of aquaculture.. Probably aquaculture began in China before very long ago, due to the wants of an emperor to have an unremitting supply of fish in his land. It is supposed that the proficiencies for keeping fish in ponds originated in China with fishermen who kept their extra catch alive temporarily in baskets submerged in rivers or small bodies of water created by damming one side of a river bed.(Ling, S.W,Aquaculture in Southeast Asia: A Historical Overview,A Washington Sea Grant Publication).
Another theory is that aquaculture arose from ancient practices for pinning down fish, with the operations steadily improving from trapping-holding to trapping-holding-growing, and finally into complete agriculture or farming practices.
Methods of Aquaculture
The methods of aquaculture’s farm-to-table process can differ from species to species. Generally, there are four stages of the production chain, starting in hatcheries and ending at the seafood counter in your grocery store. Four stages are:
stages of the production chain
Stages of Production; Image: Ruddra
Each of these stages may vary concerning its effect on the environment and the quality and safety of the seafood they produce.
The first stage in the aquaculture production chain is the hatchery. This is where the breeding of fish, hatch
Similar to Balancing the pond ecosystem in shrimp farming (20)
Micro RNA genes and their likely influence in rice (Oryza sativa L.) dynamic ...Open Access Research Paper
Micro RNAs (miRNAs) are small non-coding RNAs molecules having approximately 18-25 nucleotides, they are present in both plants and animals genomes. MiRNAs have diverse spatial expression patterns and regulate various developmental metabolisms, stress responses and other physiological processes. The dynamic gene expression playing major roles in phenotypic differences in organisms are believed to be controlled by miRNAs. Mutations in regions of regulatory factors, such as miRNA genes or transcription factors (TF) necessitated by dynamic environmental factors or pathogen infections, have tremendous effects on structure and expression of genes. The resultant novel gene products presents potential explanations for constant evolving desirable traits that have long been bred using conventional means, biotechnology or genetic engineering. Rice grain quality, yield, disease tolerance, climate-resilience and palatability properties are not exceptional to miRN Asmutations effects. There are new insights courtesy of high-throughput sequencing and improved proteomic techniques that organisms’ complexity and adaptations are highly contributed by miRNAs containing regulatory networks. This article aims to expound on how rice miRNAs could be driving evolution of traits and highlight the latest miRNA research progress. Moreover, the review accentuates miRNAs grey areas to be addressed and gives recommendations for further studies.
Characterization and the Kinetics of drying at the drying oven and with micro...Open Access Research Paper
The objective of this work is to contribute to valorization de Nephelium lappaceum by the characterization of kinetics of drying of seeds of Nephelium lappaceum. The seeds were dehydrated until a constant mass respectively in a drying oven and a microwawe oven. The temperatures and the powers of drying are respectively: 50, 60 and 70°C and 140, 280 and 420 W. The results show that the curves of drying of seeds of Nephelium lappaceum do not present a phase of constant kinetics. The coefficients of diffusion vary between 2.09.10-8 to 2.98. 10-8m-2/s in the interval of 50°C at 70°C and between 4.83×10-07 at 9.04×10-07 m-8/s for the powers going of 140 W with 420 W the relation between Arrhenius and a value of energy of activation of 16.49 kJ. mol-1 expressed the effect of the temperature on effective diffusivity.
Natural farming @ Dr. Siddhartha S. Jena.pptxsidjena70
A brief about organic farming/ Natural farming/ Zero budget natural farming/ Subash Palekar Natural farming which keeps us and environment safe and healthy. Next gen Agricultural practices of chemical free farming.
Willie Nelson Net Worth: A Journey Through Music, Movies, and Business Venturesgreendigital
Willie Nelson is a name that resonates within the world of music and entertainment. Known for his unique voice, and masterful guitar skills. and an extraordinary career spanning several decades. Nelson has become a legend in the country music scene. But, his influence extends far beyond the realm of music. with ventures in acting, writing, activism, and business. This comprehensive article delves into Willie Nelson net worth. exploring the various facets of his career that have contributed to his large fortune.
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Introduction
Willie Nelson net worth is a testament to his enduring influence and success in many fields. Born on April 29, 1933, in Abbott, Texas. Nelson's journey from a humble beginning to becoming one of the most iconic figures in American music is nothing short of inspirational. His net worth, which estimated to be around $25 million as of 2024. reflects a career that is as diverse as it is prolific.
Early Life and Musical Beginnings
Humble Origins
Willie Hugh Nelson was born during the Great Depression. a time of significant economic hardship in the United States. Raised by his grandparents. Nelson found solace and inspiration in music from an early age. His grandmother taught him to play the guitar. setting the stage for what would become an illustrious career.
First Steps in Music
Nelson's initial foray into the music industry was fraught with challenges. He moved to Nashville, Tennessee, to pursue his dreams, but success did not come . Working as a songwriter, Nelson penned hits for other artists. which helped him gain a foothold in the competitive music scene. His songwriting skills contributed to his early earnings. laying the foundation for his net worth.
Rise to Stardom
Breakthrough Albums
The 1970s marked a turning point in Willie Nelson's career. His albums "Shotgun Willie" (1973), "Red Headed Stranger" (1975). and "Stardust" (1978) received critical acclaim and commercial success. These albums not only solidified his position in the country music genre. but also introduced his music to a broader audience. The success of these albums played a crucial role in boosting Willie Nelson net worth.
Iconic Songs
Willie Nelson net worth is also attributed to his extensive catalog of hit songs. Tracks like "Blue Eyes Crying in the Rain," "On the Road Again," and "Always on My Mind" have become timeless classics. These songs have not only earned Nelson large royalties but have also ensured his continued relevance in the music industry.
Acting and Film Career
Hollywood Ventures
In addition to his music career, Willie Nelson has also made a mark in Hollywood. His distinctive personality and on-screen presence have landed him roles in several films and television shows. Notable appearances include roles in "The Electric Horseman" (1979), "Honeysuckle Rose" (1980), and "Barbarosa" (1982). These acting gigs have added a significant amount to Willie Nelson net worth.
Television Appearances
Nelson's char
WRI’s brand new “Food Service Playbook for Promoting Sustainable Food Choices” gives food service operators the very latest strategies for creating dining environments that empower consumers to choose sustainable, plant-rich dishes. This research builds off our first guide for food service, now with industry experience and insights from nearly 350 academic trials.
UNDERSTANDING WHAT GREEN WASHING IS!.pdfJulietMogola
Many companies today use green washing to lure the public into thinking they are conserving the environment but in real sense they are doing more harm. There have been such several cases from very big companies here in Kenya and also globally. This ranges from various sectors from manufacturing and goes to consumer products. Educating people on greenwashing will enable people to make better choices based on their analysis and not on what they see on marketing sites.
"Understanding the Carbon Cycle: Processes, Human Impacts, and Strategies for...MMariSelvam4
The carbon cycle is a critical component of Earth's environmental system, governing the movement and transformation of carbon through various reservoirs, including the atmosphere, oceans, soil, and living organisms. This complex cycle involves several key processes such as photosynthesis, respiration, decomposition, and carbon sequestration, each contributing to the regulation of carbon levels on the planet.
Human activities, particularly fossil fuel combustion and deforestation, have significantly altered the natural carbon cycle, leading to increased atmospheric carbon dioxide concentrations and driving climate change. Understanding the intricacies of the carbon cycle is essential for assessing the impacts of these changes and developing effective mitigation strategies.
By studying the carbon cycle, scientists can identify carbon sources and sinks, measure carbon fluxes, and predict future trends. This knowledge is crucial for crafting policies aimed at reducing carbon emissions, enhancing carbon storage, and promoting sustainable practices. The carbon cycle's interplay with climate systems, ecosystems, and human activities underscores its importance in maintaining a stable and healthy planet.
In-depth exploration of the carbon cycle reveals the delicate balance required to sustain life and the urgent need to address anthropogenic influences. Through research, education, and policy, we can work towards restoring equilibrium in the carbon cycle and ensuring a sustainable future for generations to come.
1. JANUARY/FEBRUARY2017
Volume 13 Number 1
ISBN 1793 -0561
MCI(P)013/10/2016PPS1699/08/2013(022974)
www.aquaasiapac.com
Industry review: Shrimp
production trends in Asia
Managing off-flavour in
Thai seabass
A mycotoxin threat to
yellow catfish
'Back to Basics' for
aqua feeds
Genetic improvement of
giant freshwater prawn
Moving aquaculture in Taiwan
3. 8 January/February 2017 AQUA Culture Asia Pacific Magazine
Shrimp Culture
Balancing the pond ecosystem
in shrimp farming
Poor shrimp farming management disrupts the
delicate balance in shrimp pond ecosystems;
controlling feed inputs and managing the pond
environment are crucial.
By Poh Yong Thong
One of the biggest problems in shrimp farming management is
overfeeding. In their enthusiasm to grow shrimp faster, farmers
believe that providing more feed is critical. This seemingly
harmless act is actually the cause of many pond water quality
and shrimp disease problems.
In the wild, shrimp are generally not densely crowded together;
shrimp density is perhaps only 1 shrimp in 5 m2
area or even lower.
However, when we began to domesticate and farm shrimp such
as the vannamei shrimp in Asia, we tend to use stocking density
as high as 100 post larvae (PL) or more per square metre to
maximize returns. We then call this an intensive culture system.
In the shrimp pond, there are microorganisms that keep the
pond ecosystem in a balance state. Excess inputs in the form of
feed and the resulting wastes (faeces, other metabolic wastes
such as ammonia, nitrite, nitrate and carbon dioxide) are being
neutralised by the myriad of microorganisms, algae and plants. If
at one point in time, there is excess feed in the pond, the limited
amount of microorganisms in the pond will not be able to cope
with the sudden increase in nutrient inputs, and the excess feed
will disintegrate and pollute the water with poisonous pollutants
which promote the growth of pathogenic bacteria that are
harmful and result in shrimp disease problems and mortality.
The ecosystem of a lake
In a lake which is exposed to nutrient overloading from sewage
or agriculture fertilisers, algal blooms will occur. The algae will
respire at night resulting in severe depletion of dissolved oxygen.
The large amount of carbon dioxide produced by the algae at
night lowers the pH of the lake water, resulting in the in the
release of toxic hydrogen sulphide gas.
On the other hand, during a bright sunny day, algae will
photosynthesise and remove huge amounts of carbon dioxide,
thus resulting in increased pH levels. High pH is detrimental
to many living organisms in the lake because high pH levels
of over 8.5 result in the equilibrium of ammonium in the lake
The ecosystem in the pond is similar to that in an aquarium as seen here.
Overfeeding will pollute the water and kill your shrimp
to be shifted towards the release of a high amount of toxic
ammonia. The deleterious depletion of oxygen at night together
with the fluctuation in pH levels between night and day, affect
the dynamics of hydrogen sulphide and ammonia production
resulting in severe damage to the fish and other biota in the lake.
Eutrophication which originates from the Greek word
“eutrophia” meaning “well-nourished, is nature’s response to the
presence of excess nutrients which induces explosive growth of
plants and algae, resulting in serious fluctuation of oxygen and
pH between day and night, causing the collapse of the aquatic
ecosystem.
The high nutrient loading in the lake will also encourage the
proliferation of pathogenic bacteria. It is therefore not surprising
that a eutrophic body of water carries a high bacterial and fungal
load.
The intensive shrimp pond
In a commercial shrimp farm, often more than 100 shrimp are
crowded into a 1 m2
area. This is an unnatural condition. The high
number of more than 100 PL/m2
of shrimp means that the small
amount of water and pond bottom relative to the unnaturally high
number of shrimp (compared to perhaps 1 shrimp in 5 m2
in the
wild) requires proportionally more than 500 times the amount
of feed. Shrimp farmers must be able to manage this excessively
high amount of feed properly. The risks are high and striking a
balance is difficult. If he or she overfeeds just by a small amount,
the overloaded system will result in the microorganisms being
unable to neutralise the load of nutrient inputs and the result is
eutrophication of the pond.
Dead fish in a eutrophic lake
In a commercial shrimp
farm, often more than 100
shrimp are crowded into a
1 m2
area
4. Believe in what you see
We can see it inside, you will see it from the outside!
BACTOCELL activates and associates with the gut mucosa, which is the key to a true probiotic effect.
If you need to see more, years of research and field applications have provided compiling evidence
of BACTOCELL’s modes of action and benefits at cellular, animal and farm level.
Discover the world of BACTOCELL, the pioneering gut health probiotic in aquaculture.
LACTIC ACID BACTERIA FOR AQUACULTURE
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aqua@lallemand.com
Not all products are available in all markets nor all claims allowed in all regions.
5. 10 January/February 2017 AQUA Culture Asia Pacific Magazine
Shrimp Culture
Feed management is the key
to success in shrimp farming
The pioneer Taiwanese farmers that practise intensive shrimp
farming have an adage stating that ' it is better to feed the shrimp
to only 80% satiation. This is great wisdom as the ecosystem of
an intensive pond culture system is very fragile. Any degree of
overfeeding will tilt the system towards an eutrophic condition.
In many farms in Malaysia, Indonesia and Thailand, withholding
feeds to shrimp at specific times has produced good results. In
most of these farms, feeding stops when the sun goes down.
Contrary to the natural biorhythm of the shrimp, no feed is given
at night when the dissolved oxygen is low since no photosynthesis
takes place. During the day, there may be 4- 5 feedings in an
intensive culture system. When shrimp are more than 60 days
old, they are not given feed 2 to 3 times in a week depending on
the water quality, so as to allow the microorganisms in the pond
to catch up on neutralising excess nutrients.
All shrimp farmers are aware of the importance of withholding
feeds periodically or even to stop feeding completely, whenever
there is water quality or shrimp disease issues in the pond.
The use of probiotics
In nature, over time, bacteria will establish themselves in sufficient
numbers to assimilate the extra nutrients in the culture system.
However, where feed quantities are excessive, the system will lose
equilibrium in the ecosystem with sudden large nutrient inputs.
Timely addition of reputable commercial probiotics can play a
role in supplying an array of selected bacteria to assist in mopping
up the excess nutrients. Some farms conduct daily pathogenic
bacteria analyses and add more probiotics into the ponds which
have a higher concentration of pathogenic bacteria. This practice
is effective in re-establishing the ecosystem equilibrium.
There are two major groups of Vibrios depending on the colour
of the colonies formed on TCBS agar plates. The yellow colonies
are benign. These are Vibrio alginolyticus and V. fluvialis. The
green colonies are pathogenic. These are V. parahaemolyticus,
V. chlorelae, V. vulnificus and V. mimicus. When the green colonies
dominate, more probiotics have to be administered to the pond
water.
It is also good practice to apply proportionally more anaerobic
probiotics to the pond at the later stages of shrimp farming to
conserve oxygen for the shrimp.
(pictures credit: www.microbiologyinfo.com)
Table 1. Acceptable number of Vibrio (CFU/mL)
Before
stocking
30 days of
culture
60 days of
culture
Pond water 1x102
1x103
1x104-5
Shrimp blood 1x102
1x103
Gut 1x103
1x104
Hepatopancreas 1x103
1x104-5
Water exchange
Depending on the water exchange regime practised, the shrimp
pond ecosystem will fall into one of the three systems below:
• bioflocs system with little or 3 to 5% daily water exchange
• oligotrophic system with more than 30% daily water exchange
• phytoplankton system with intermediate or occasional high
water exchange
A biofloc system is difficult to manage and usually yields
inconsistent results due to fluctuating sunlight. Its greatest
advantage is its ability to produce stable pH. If excessive sunlight
can be partially shielded, a biofloc system will be able to produce
more consistent results.
The liberal water exchange system will produce an oligotrophic
system in which the pond water is relatively devoid of excessive
nutrients and hence pathogenic bacteria.
When there is sporadic high water exchange which may
be due to occasional availability of water due to high tides,
phytoplankton tend to dominate immediately after the excessive
water exchange. Due to photosynthesis in the presence of
sunlight and respiration at night, the pH in this system tends to
have large daily variations, high during intense sunshine and low
at night. This pH swing will in turn results in high toxic ammonia
at high pH during the day and high toxic hydrogen sulphide at
low pH at night. This system is deleterious to shrimp farming.
Central discharge and siphoning
The ecosystem in intensive shrimp culture pond is very vulnerable
due to high nutrient input in a small volume of water. Nutrient
loading results in the production of excessive ammonia and
hydrogen sulphide, resulting in the proliferation of pathogenic
bacteria. In order to reduce nutrient loading, measures must be
taken to discharge sludge which is formed from faeces, dead
plankton and microbes. This can be achieved by the appropriate
arrangement of aerators which produces circulation in such a
way so as to accumulate the sludge in a designated area. The
sludge can be discharged periodically by a discharge system or
by siphoning physically. The central discharge channels common
in ponds in Indonesia has been described in a previous article
(Aqua Culture Asia Pacific, issue May/June 2014, p8-10).
Poh Yong Thong is Assistant Director, Technical
Services Gold Coin Aquaculture Group, based in
Malaysia. Email: yt.poh@goldcoin-group.com
TCBS plate yellow Vibrio colonies TCBS plate green pathogenic
Vibrio colonies