The Effects of Climate Change on Benthic Macroinvertebrate Communities

1. The Effects of Climate Change on Benthic Macroinvertebrate Communities Ecological Risks Associated with Future Anthropogenic Impacts in Vermont’s Streams By: Tanner Williamson, Samuel Parker, Emily Matys Jacqueline Maisonpierre & Pace Goodman

2. Overview • Combined effects of climate change and urbanization are changing the ecology of Vermont’s streams • These changes will affect communities of benthic macroinvertebrates (BMI) • Goal of this project was to use benthic macroinvertebrates as an indicator of stream health as to evaluate the impacts of climate change and urbanization on Vermont’s streams • We found the compounding effects of urbanization to pose the largest potential threat to BMI populations

3. Approach: Data Collection Problem Formulation Analysis Effects Exposure Risk Characterization Risk Management EPA’s Ecological Risk Assessment framework • Emphasized problem formulation, data analysis and risk characterization Location of study • Papers were relatively rare, so best judgment was used on which data to utilize • However, all assisted in gaining depth of knowledge concerning benthic macroinvertebrates • Individuals, species, and communities The theory of stationarity • Variables chosen for analysis were studied in past conditions • Must assume conditions at that point in time are similar to those into the future • Additional environmental and ecological variables may change in years to come

4. Background: Climate Change Scenarios High Emission Scenario: • Winters could warm by 8 to 12°F and summers by 6 to 14°F by the year 2100 • More precipitation will fall as rain and less as snow • Drought frequency in late summer and fall is projected to increase significantly • Seasons are expected to shift, spring will be earlier and potentially wetter and fall could become drier Low Emission Scenario: • Temperature increases of 5 to 7.5°F in winter and 3 to 7°F in summer by the end of the century Under Both Scenarios We Expect to See… • Increased winter precipitation as rain • Increased magnitude and frequency of heavy rain events, which, in turn, will cause an increase to the magnitude and frequency of large flow events in stream and river channels

5. Macroinvertebrate Information: • Benthic macroinvertebrates are small, aquatic organisms that inhabit the substrate on the bottom of streams and rivers. • Orders Commonly Found in VT: • (a) Ephemeroptera (Mayflies) • (b) Plecoptera (Stoneflies) • (c) Trichoptera (Caddisflies) • Diptera (True flies) • Coleoptera (True beetles) • Megaloptera • Primary Consumers • Feed on detritus or other macroinvertebrates • Sensitivity to stressors in the aquatic system make them excellent biological indicatory species (a) (b) (c) (c)

6. Climate Change Urbanization Higher Ambient Temperatures Extreme Precipitation Events Increased Impervious Surfaces Sources Extreme Flow Events Water Temperature Increase Low Flows (Droughts) Stressors High Flows (Floods) Decrease in D. O. Concentration Increased Siltation Effects Increase in Respiration Rate Increased Erosion Organism Stress/Morality Shifts in Benthic Macroinvertebrate Communities Habitat Loss Endpoints Decrease of Fecundity and Changes in Trophic Structure Concept Model: Figure. Conceptual model exploring the sources (rectangles), stressors (hexagons), effects (parallelogram), and endpoints (ovals) of human impacts on benthic macroinvertebrates.

7. Variables Influencing Stream Health Considered • Dissolved Oxygen • Sedimentation Loads • High Flow Events & Drought Events • Compounding Effects of Urbanization

8. Drought Events http://blogs.tnr.com/tnr/blogs/environmentandenergy/archive/2009/02/02/california-s-snowpack-problem.aspx

9. What is drought? (Modified from: Boulton 2003)

10. Macroinvertebrate response to drought (Modified from Boulton 2003)

11. MIV response to drought (cont.) (Modified from Suren 2006)

12. Drought: Climate Considerations (Modified from Hayhoe et al. 2006)

13. Drought: Climate Considerations (Cont.) (Hackett 2009)

14. High Flow Events Increased storm frequency and intensity as a result of Climate Change Graph #1 Graph #2 Graph #3 Projected increases of extreme precipitation (1) Precipitation intensity (2) Number of days per year with > 2” of rain (3) Maximum amt. of rain to fall During a 5 day period (NECIA-Northeast Climate Impact Assessment 2006)

15. Effects of High Flow Events on Macroinvertebrates • Flood events cause physical scouring and moving of the riverbed • Macroinvertebrates can be crushed or swept into the stream flow • Communities are resilient, Bradt et al. (1999) found stability and resilience in BMI assemblages in a PA river over 25 years • Life history strategies of asynchronous, multivoltine life cycles aid in the stability of maroinvertebrate communities

16. High Flow Events • Marked decrease in all groups of taxa post flooding events • Resilience shown in all species • Capacity to return to some previous state following a perturbation • In Suren & Jowett (2001) study relative abundance of 14 taxa increased after small floods while abundance of 10 taxa decreased after the largest flood Figure. Relative flow of the Waipara River and relative density of selected invertebrate taxa averaged across riffles and runs collected in the Waipara River between September 1998 and June 2001 (Suren and Jowett 2007)

17. Sedimentation • Climate change has the potential to indirectly increase the rates of erosion and sedimentation • Increased storm events • Presently, 34% of United States waters deemed impaired are due to excessive sedimentation • Climate change along with anthropogenic stressors (i.e. urbanization) have great potential to influence macroinvertebrate populations Effects of Sedimentation on Macroinvertebrates • Most populate stream segments composed of cobble and pebble substrates • Size of particles is incredibly important in survivorship • Suspended and deposited sediments modify the habitat structure • Limit interstitial space • Inhibits filter feeders

18. Increased fine sediment • Kaller et al. 2004 found fine particles (<0.125mm) are detrimental to EPT taxa along with overall macroinvertebrate density, biomass and taxa richness • Identified a threshold for BMIs at a percent of fine sediments >0.8% • Decline in richness at a percent of fine sediments >0.8% • Richness was preserved where fine sediment did not reach 0.8% Sensitivity of Macroinvertebrates • Some sensitive species cannot adapt to increases in fine sedimentation • Those who rely on substrates for attachment • Threshold of fine sediment is increased for scrapers and grazers to 40% • Burrowing species have the potential to benefit from an increase in fine particulates • Changes in individual abundance will be most effected rather than diversity

19. Contradictory studies • Vasconcelos et al. 2008 found that coarse sediment (0.25-0.80mm) was most detrimental to macroinvertebrates • Abrasion was the cause of most mortality • Larsen et al. 2009 found no correlation between increased sediment and macroinvertebrate species • Results proven to be related more closely to land use and water quality

20. Dissolved Oxygen

21. Dissolved Oxygen (Ficke et al. 2007) Increased Air Temperature Increased Water Temperature Higher Metabolic Rates Reduced DO

22. Dissolved Oxygen (Jacobsen et al. 2008) • Eight Unpolluted Sites: • No correlation between DO fluctuations (max, mean and min) with BMI indices • All Twelve Sites: • Positive correlation between BMI indices and O2 saturation • Minimum DO had more significance than mean DO

24. Dissolved Oxygen (Beyenne et al. 2007) • Diatoms serve as better stream health indicators due to reduced vulnerability

25. Variable Interactions Reduced DO Higher Flow Events More Drought More Sedimentation

26. Compounding Effects of Urbanization • The direct link between stream health and urbanization makes it difficult to precisely identify the stressors associated with climate change. • Urbanization ultimately increases the impervious cover of a watershed. • High flow events would be more likely, which could increase erosion and sedimentation. • The water running off the impervious surfaces is likely to be much hotter than water running off a shaded forest, which would increase water temp and decrease DO. • A loss in vegetation could reduce the ET flux and make droughts more likely. The relationship between TIA and EPT richness for urban and rural reaches (Modified from: Fitzgerald 2007).

27. Risk Assessment First, We assigned a risk rank. • Low Flows and Droughts • Increased Flow Events • Sedimentation • Dissolved Oxygen Then, simply multiplying by the relative risk rate by the total impervious area we can get a scaled net effect of Climate Change and Urbanization on Macroinvertebrate Communities

28. Expanding Effect • Game Fish • Water Quality • Any other ideas? • 4. Any other ideas?

29. Recommendations • Halt or mitigate future anthropogenic climate change by: • Reducing Greenhouse Gas emissions • Reduce draw-downs during low flow periods • Promote the development of mature riparian forests to: • Provide shading • CWD habitat • Air & surface water temperature moderation • Reduce sedimentation • Improve water quality • Develop land use practices that: • Reduce the % of impervious surfaces • Encourage less intensive agricultural tillage techniques Hybrid Vehicle Rain Garden

30. Recommendations (Cont.) Healthy Riparian Buffer Poor Riparian Buffer

31. Questions… Oh No, Climate Change!!