Download to read offline
More Related Content
![Jsc revised rifka-presentation for-990626_(revised[1]](https://cdn.slidesharecdn.com/ss_thumbnails/jsc-revisedrifka-presentationfor990626revised1-110520095457-phpapp02-thumbnail.jpg?width=640&height=640&fit=bounds)
![Aquatic Bacterial Community In Peatland Streams [Marcella Branagan]](https://cdn.slidesharecdn.com/ss_thumbnails/aquaticbacterialcommunityinpeatlandstreamsmarcellabranagan-101117100511-phpapp02-thumbnail.jpg?width=640&height=640&fit=bounds)
Thesis powerpoint DD
- 1. Effects of GrowingSeason Flow Regime on Stream Periphyton Growth in a Coastal Plain Stream David Diaz, M.S. Candidate, Ecology Advisors Dr. Paul V. McCormick, Dr. Alan Covich Thesis Defense: September 18th 2015
- 2. Outline Background: Rationaleand site description Part 1: Influence of discharge and nutrient availability on periphyton biomass and composition Part 2: Effects of discharge-grazer interactions on periphyton biomass and composition Conclusion
- 3. Rivers and streams Ecosystem services Human and environmental water needs Environment flows
- 4. Environment flows Flow:Key Driver *http://projects.inweh.unu.edu/
- 5. Lower Flint RiverBasin Agricultural water withdrawals Drought
- 6. Seasonal flow patternsin a coastal plain stream Seasonal Hydrograph of Ichauwaynochauway 1970- 2015
- 7.
- 8. Flow-periphyton relationships Ecologicalimportance of periphyton Flow effects on periphyton
- 9. Outline Background Part1: Influence of discharge and nutrient availability on periphyton biomass and composition Part 2: Effects of discharge and grazer interactions on periphyton biomass and composition Conclusion
- 10.
- 12.
- 13. Hypotheses Study 1:Higher periphyton accumulation at lower discharge due to reduced shear stress Study 2: More nutrient limitation at lower discharge. ◦ Phosphorus is limiting nutrient
- 14. Methods- Experimental design Study 1: ◦5 discharge treatments across 15 channels 3 replicates : L, ML, M, MH, H (20 fold range across treatments) 4 tiles/channel, 2-3 days for 28 Days Samples processed for AFDM, chl a and other pigments Study 2: ◦ Same discharge treatments Nutrient enrichment : Control, Phosphorus, Nitrogen + Phosphorus Sampled every 2-3 days for 33 days. Processed for AFDM, chl a and other pigments
- 15. Analysis Biomass accumulationpatterns modeled using polynomial regression ◦ Growth rates estimated from linear coefficients ◦ Rates compared among treatments using 95% confidence intervals ANOVA analysis and Tukey’s significance test to compare maximum values of AFDM, chl a and for pigment concentrations.
- 16.
- 17. All models significantat p<.05 level. R^2>
- 19.
- 21. 0 500 1000 1500 2000 2500 3000 4 7 1114 18 21 25 28 AIRatio Day * * * * = Statistically Significant Autotrophic Ratio= AFDM/chl a
- 22.
- 24.
- 25. 0 0.5 1 1.5 2 2.5 3 3.5 4 Control P N+P Pigmentconcentration (nmol/cm2) Diatoms 0 5 10 15 20 25 30 35 ControlP N+P Pigmentconcentration (nmol/cm2) 0 5 10 15 20 25 30 35 Control P N+P H MH M ML L 0 0.5 1 1.5 2 2.5 3 3.5 4 Control P N+P H MH M ML L 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 Control P N+P Pigmentconcentration (nmol/cm2) Green Algae 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 Control P N+P H MH M ML L Total Pigments Day 4 Day 4 Day 4 Day 33 Day 33 Day 33
- 26. Part l Summary Greater accumulation of AFDM (higher AI ratio) at higher discharge Diatom dominance in all treatments. Higher relative abundance of green algae in lower treatments Nutrient enrichment effect greatest at higher discharges
- 27. Background Part1: Influence of discharge and nutrient availability on periphyton biomass and composition Part 2: Effects of discharge and grazer interactions on periphyton biomass and composition Conclusion
- 28.
- 29. Hypothesis Snail grazerscan limit periphyton biomass under a range of periphyton growth conditions related to discharge.
- 30. Methods Marked andweighed snails ◦ Used similar ambient density for treatments 3x2 factorial design. 3 discharge treatments (L,M,H)and 2 grazer treatments.
- 31. Analysis Accumulation patternsmodeled using polynomial regression ◦ Average growth rates estimated from linear coefficients ◦ Rates compared among treatments using 95% confidence intervals 2-way ANOVA and Tukey’s significance test used to compare maximum values of AFDM, chl a and for pigment concentrations. Snail growth
- 33.
- 34.
- 36.
- 37. 0 5 10 15 20 25 30 L M H Pigmentconcentration (nmol/cm2) Ungrazed Grazed TotalPigments Day 4 0 2 4 6 8 10 12 L M H Pigmentconcentration (nmol/cm2) Ungrazed Grazed Diatoms Day 4 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 L M H Pigmentconcentration (nmol/cm2) Ungrazed Grazed Green Algae Day 4 0 5 10 15 20 25 30 L M H Total Pigments Day 33 * Grz=.011* Dch=.008* Grz x Dch= .045* 0 2 4 6 8 10 12 L M H Diatoms Day 33 * Grz=.011* Dch= .025* Grz x 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 L M H Green Algae Day 33 * * Grz=.582* Dch=.152* Grz x Dch=.464
- 39. Part ll Summary AFDM and chl a pigment concentrations increased with discharge. Diatom dominance in all discharge treatments. Grazers had greater effect at higher discharges Snail growth rate decreased with higher discharge
- 41. Conclusion Rapid periphytonaccumulation potential during the summer growing season ◦ High light availability ◦ Stable flow regime Local flow conditions control periphyton patterns ◦ Accumulation rates and maximum biomass ◦ Mat heterotrophy ◦ Taxonomic composition Grazers exert limited control over periphyton
- 42. Implications Climate Change:Drought duration and frequency influence stream primary production Human water Use: Changes in instream flows affect periphyton spatial patterns Lower flow conditions may become more common in the future Food web dynamics
- 43. Acknowledgements • Special thanksto Dr. McCormick and Dr. Covich • Jones Center Staff and Students • Chelsea Smith, J.R Bolton, Steve Shivers • Committee- Dr. Steve Golladay, Dr. Mary Freeman, Dr. Susan Wilde • Dr. Matt Waters
- 44.
Editor's Notes
- #2 Outline I’ve divided my talk into four sections Background on my topic and the stream that I worked in.
- #4 Rivers and Streams Ecosystem Services- water purification, nutrient cycling, primary production, habitat for aquatic biota Human use of water resources for consumption, irrigation, energy production Increased human water consumption coupled with finite freshwater supplies makes it difficult to balance human and ecological needs for water.
- #5 Environmental flows Aquatic ecologists recognize that the flow regime is a key driver of ecosystem function for rivers: Determines the type physical habitats and affects geomorphology of streams over time. Physical structure in turn affects the movement and persistence of aquatic biota. Environmental Flows- Management frameworks aim to find the range of flow conditions needed to maintainhealthy aquatic systems. This frame work can help us understand compatibility between the water needs of human and natural systems.
- #6 Lower Flint River Basin (example) *The lower Flint River Basin (LFRB), located in Southwestern Georgia is one of the most productive agricultural regions in the U.S. *Since the 1970s the regional economy has depended on row-crop agriculture supported by center-pivot irrigation, which increased water withdrawal from both surface and groundwater sources. *Prolonged dry periods are projected to be more common as a result of global climate change in Georgia. The LFRB has experienced periods of below normal rainfall, including three droughts, during the past decade *Withdrawals often coincide with seasonally decreased summer low flows, exacerbating the conserquences of low flows during the summer.
- #7 Seasonal flow patterns in a coastal plain stream Hydrograph Black water systems- During the winter and spring months, we observe a lot of run off and a lot of DO matter coming into the stream, with very low light availability, which can limits periphyton growth. During the summer is the best opportunity of periphyton growth, because of the surface ground water connection , much of the water is clear ground water as opposed to stained surface water inputs. These are the periods of the years when the potential for periphyton growth is greatest in this stream. Flow regimes during summer are being altered by discharge. Question- Under these seasonally favorable conditions for periphyton growth, what effect does discharge have on periphyton growth and composition?
- #9 Flow Ecology My study was focused on the effects of the flow regime on periphyton growth. Periphyton is a complex mixture of algae, bacteria, and fungi that is attached to submerged surfaces in most streams. It is a primary energy source in most lotic food webs, regulate nutrient spiraling can influence chemical and physical habitat conditions for stream organisms. In excess quantities can be considered a nuisance. May negatively affect water clarity, limit growth of submerged aquatic vegetation, alter habitat quality, and affect invertebrate grazing communities and food web dynamics. Hypothetical relationship between flow and periphyton in coastal plain streams Flow influences factors that can affect algal growth and biomass both directly and indirectly through its influence on temperature, light and nutrient availability As I’ll describe in more detail later, my study focused primarily on the direct effects of flow, which can be positive or negative. Positive because it can increase the supply of algal cells/propogules, and negative because faster flow environments can increase turbulence and sheer stress. Flow affects periphyton through its influence on nutrient supply rates. Discharge influences the concentration and uptake potential of nutrients by benthic communities. Higher water discharge has the potential to increase nutrient supply rates and decrease the diffusive boundary layers for higher nutrient uptake by algae. These changes in nutrient availability can regulate rates of primary production. Stream grazers can also play an important role in controlling periphyton growth, and I was interested in how that influence might be affected by the flow regime.
- #11 Site My study was conducted in the lower portion of Ichawaynochaway Creek , a 5th order tributary of the Lower Flint River. Jones Center during the summer and late fall of 2014.
- #12 Experimental Stream Facility Flow through system, where water was pumped to channels to the stream. Discharge in individual channels controlled by spigots Channels lined with clay tiles that were used to sample periphyton growth Temperatures held constant across treatments
- #15 Methods Randomly selected from 4 sections. Decrease variation in conditions. Tiles scraped and placed upside down. Used standard protocols for sampling. AFDM- Total organic matter ( an estimate of overall periphyton biomass including photo and heterotrophic components), chla – algal biomass, and pigments associated with algal composition. Nutrient enrichment- reinitiated 5 discharge treatments. Added slow release fertilizers in panty hose bags for enrichments. This allowed for slow leaching. Samples processed for same parameters as study one
- #17 X axis=time , y –axis=AFDM, each point represents the mean for 3 replicate channel discharge treatment +-one standard error. Throughout the course of the experiment, AFDM tended to increase, with increasing discharge. * Discharge had a positive effect on AFDM .
- #18 Based on our regression models, the growth rates were higher at the higher discharge treatments, which was contrary to our expectations
- #19 Chla on the other hand, did tend to be lower at the higher discharge treatments, particularly as the study progressed. This was more consistent with our expectations. In this case initially there was no major trends, but at the end there were higher chla concentrations in lower discharges.
- #20 Polynomial- linear was accumulation phase and quadratic term was the sloughing phase/ reduced chl a Ex: accumulation rates based on linear coeff were similar for all treatments earlier in the study but then there was a significant quadratic term for higher discharge treatments, which resulted in lower biomass compared to lower treatments towards the end of the study
- #21 The maximum AFDM also increased with discharge, while maximum cholorphyll values tended to be higher in the lower discharge. What we observed was a shift toward a more heterotrophic assemblage with increasing discharge.
- #22 This is shown here using the calculated AI ratio which is AFDM/Chla. Higher AI ratios indicate a more heterotrophic community while lower ratios indicated a more autotrophic community. The AI ratios tended to be higher at the higher discharge treatments, particular towards the end of the study where we saw higher AFDM and lower chla values.
- #26 Pigment analysis is in part showing diatom dominance (in term of relative abundance) in all treatments but increased green algal abundance in low flows.
- #27 Nutrient study- more nutrient dissolution of nutrients… potential for more nutrient dissolution if more water blasting through bags. Where nutrients important by self? (no, when controls were compared to nutrient additions, regardless of discharge, there were no significant differences – used max biomass for afdm and chl a). Was there an interaction with discharge? (no replication, cannot test for it significantly) Higher discharge= Higher AFDM. In higher discharges nutrient enrichment had higher AFDM
- #28 Stream grazers often limit algal biomass but may not be able to respond to a rapid increase in algal growth rates that exceeds herbivory rates. The purpose of this study is to investigate how summer low-flow conditions affect algal growth and biomass and the ability of stream herbivores to respond to changes in this food resource.
- #29 Grazers regulate periphyton biomass and growth through ingestion and physical disturbance. The majority of studies have concluded that algal biomass almost always declines in the presence of herbivores, though the outcome can often depend on the type of alga and herbivore involved
- #33 Discharge was the most influential parameter. In some treatments there appeared to be differences between grazers
- #38 Pigments- Grazing effects intensified with increasing discharge as indicated by a significant interaction term between these two factors (F=2.870, p=.045).
- #39 Snail growth declined with increased discharge despite the fact that there was more periphyton biomass for consumption at high discharge.
- #40 previous studies have shown higher energy/metabolic expendetures
- #41 Flow can have a direct negative affect on grazers. Effects more complicated than I originally thought.
- #42 Answers to the research objectives can provide insight into the linkages between reductions in stream discharge and periphyton growth and biomass. Exploring factors that promote rapid algal growth will provide a better understanding of the ecological impacts of human water consumption and low flows on lotic systems. This research provides greater insight into how alterations to summertime flow regimes affect periphyton ecological conditions within the LFRB. These results will increase understanding of the relationship between discharge and periphyton abundance and composition in order to predict the effects of changing flow regimes on stream ecology. Our study highlights the significance of flow and nutrient effects on algal biomass, particularly in agricultural areas where present and future anthropogenic modifications can greatly alter lotic systems
- #43 In the stream we previously observed that high biomass is positively related to lower flows which provided a basis for our initial hypothesis. We surmised that reduced flow and associated scouring increase attached algal biomass by reducing sloughing of algal cells from substrata. In our experiment, however, we found that higher flows had greater AFDM accrual. Results presented here demonstrate that flow has the potential to alter the composition and growth rates of periphyton in a controlled experiment.