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Effects of environmental change on freshwater zooplankton

Effects of environmental change on freshwater zooplankton. Dr. Sandra L. Cooke Thompson Writing Program & Biology Department Duke University Durham, North Carolina Download this file: http://www.duke.edu/~sc153/research.html. Aquatic Ecosystems & Environmental Change. climate change.

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Effects of environmental change on freshwater zooplankton

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  1. Effects of environmental change on freshwater zooplankton Dr. Sandra L. Cooke Thompson Writing Program & Biology Department Duke University Durham, North Carolina Download this file: http://www.duke.edu/~sc153/research.html

  2. Aquatic Ecosystems & Environmental Change • climate change 1 temperature UV • land use change CDOM 2 • invasive species 3 Daphnia lumholtzi

  3. UV in Aquatic Ecosystems UV-B UV-A wavelength (nm) • biological damage  lethality • vision & behavior • pathogens • photochemistry Photo by Dr. Patrick Neale

  4. UV & Temperature Photoenzymatic repair warmer more light, UV cooler darker, low UV

  5. Diel Vertical Migration (DVM)

  6. How does zooplankton DVM vary across UV and temperature gradients? UV-sensitive species UV-tolerant species Daphnia catawba Leptodiaptomusminutus

  7. Field Site – Lake Giles located in Poconos (northeastern PA) very transparent => high UV levels

  8. -UV treatment: 6 columns made of plastic that blocks UV +UV treatment: 6 columns made of plastic that allows UV through (all columns let visible light through)

  9. Depth (m) 1 2 3 4 5 6 7 8 9 Ran a nighttime experiment (9 pm – 3 am) Ran a daylight experiment (11:15 am – 4:30 pm) 10 11

  10. UV-B PAR Cooke et al., 2008 CJFAS

  11. Daphnia catawba -UV +UV Cooke et al., 2008 CJFAS

  12. Leptodiaptomus minutus -UV +UV Cooke et al., 2008 CJFAS

  13. Implications • UV may constrain some zooplankton species to sub-optimal temperatures, which may compromise fitness. • Climate change context – research suggest that in some lakes: • UV transparency may increase • Thermal gradients may steepen

  14. Potential student-centered projects Are warm-water zooplankton sensitive to UV? Does temperature influence their UV-sensitivity? Doable with minimal equipment! Cooke et al., 2006 FWB

  15. Potential student-centered projects • Do zooplankton use low oxygen zones as refugia from predation? • If so, which species? • If so, does body size matter? • How low can they go? http://www.ncsu.edu/wq/RTRM/dp15/dp15cc.html

  16. Potential student-centered projects Doable for undergraduates

  17. Aquatic Ecosystems & Environmental Change • climate change 1 temperature UV • land use change CDOM 2 • invasive species 3 Daphnia lumholtzi

  18. UV & CDOM CDOM = Chromophoric Dissolved Organic Matter Chromophoric – absorbs UV, short visible light Dissolved – <0.7 μm Organic – plant-derived, mostly terrestrial Matter – “stuff” – mostly carbon (DOC), but also nutrients, ions, acids, etc. Quantified as concentration of dissolved organic carbon (DOC)

  19. CDOM and Environmental Change • Temperature • Precipitation • Watershed land use • Biome/ climate shifts Global trend of ↑CDOM

  20. Potential Ecological Effects of Increased CDOM • UV attenuation ↑ (less UV) • DOC, DON, etc.  food web stimulation • pH(humic & fulvic acids)

  21. How does ↑CDOM in a UV-transparent lake influence zooplankton?

  22. Potential Effects of CDOM on Zooplankton CDOM Effects Leptodiaptomus minutus Daphnia catawba more UV-tolerant less UV-tolerant UV-attenuation microbial food web-stimulation acidic benefits from ciliates, algae benefits from bacteria, HNANs, ciliates, algae less acid-tolerant more acid-tolerant

  23. Hypothesis CDOM

  24. - CDOM +CDOM Microcosm Experiment 2 weeks -UV +UV

  25. Cooke et al., 2006 Hydrobiol.

  26. Cooke et al., 2006 Hydrobiol.

  27. Implications • CDOM may have “sunscreen” and pH effects • Non-irradiated CDOM may be harmful (photochemical interactions important) • CDOM could alter plankton community composition NOTE: a longer-term, larger-scale experiment corroborates this and also points to food-web effects

  28. Potential student-centered projects • Effects of different CDOM sources on zooplankton • Positive effects of UV – does CDOM play a role? Density (L-1) Cooke & Williamson, 2006 JPR

  29. Lacawac Sanctuary

  30. Aquatic Ecosystems & Environmental Change • climate change 1 temperature UV • land use change CDOM 2 • invasive species 3 Daphnia lumholtzi

  31. North Carolina reservoirs Image from http://www.americanrivers.org/

  32. Daphnia lumholtzi 1 mm D. lumholtzi distribution in U.S. – collected and established

  33. Potential Ecological Effects of D. lumholtzi • May be more tolerant of mid-late summer conditions (tends to thrive in large rivers and reservoirs, temps ~30 C) compared to natives. • May be more resistant to predation compared to natives. larval & juvenile fish macroinvertebrates 1 mm 1 mm Largemouth bass image: George Burgess; http://www.flmnh.ufl.edu/fish/gallery/Descript/LargemouthBass/LargemouthBass.html

  34. Objectives Determine foraging efficiencies of juvenile fishes on D. lumholtzi vs. native Daphnia. Monitor the seasonal abundance and spatial distribution of D. lumholtzi and other zooplankton throughout Falls Lake. Determine if D. lumholtzi is present in B. Everett Jordan Lake (and monitor its seasonal abundance if it is) Falls ~15-20 mi. Jordan

  35. Found D. lumholtziin Jordan Lake: • Farrington Point • Vista Point • New Hope Overlook Project for my aquatic invasive species class: Monitor D. lumholtzi abundance and dominance (% of total zooplankton) at Farrington Point over the fall and spring semesters

  36. WordPress blog was helpful…

  37. Image from http://www.aslo.org/photopost/showphoto.php/photo/163/title/leptodora-kindii/cat/518 Finn et al., in press, JNCAS (5 student co-authors!)

  38. Potential student-centered projects Objective 1: Determine foraging efficiencies of juvenile fishes on D. lumholtzi vs. native Daphnia. juvenile black crappie Cooke & Johnsen, 2011 NCWRC tech. report

  39. Potential student-centered projects Objective 2: Monitor the seasonal abundance and spatial distribution of D. lumholtzi and other zooplankton throughout Falls Lake. 4 sites visited at least 1x/month Jun. 09 – Feb. 12 6 additional sites ~1x/month Jun. 09 – Dec. 11

  40. Potential student-centered projects Are spatial and temporal trends correlated with algal dynamics (e.g., cyanobacteria) or other parameters (e.g., temperature, turbidity) in Falls Lake? Cooke & Johnsen, 2011 NCWRC tech. report

  41. Potential student-centered projects Zooplankton monitoring in Oak Hollow Lake and City Lake Algal-nutrient dynamics are important…so are algal-grazer dynamics! Cooke & Johnsen, 2011 NCWRC tech. report

  42. Potential student-centered projects Daphnia lumholtzi distribution across NC and southeastern U.S.

  43. Acknowledgments • My colleagues and collaborators, especially: • Dr. JoAnn Burkholder & Dr. Robert Reed at the CAAE at NCSU • Dr. SonkeJohnsen and lab group in the Biol. Dept. at Duke • Dr. Craig Williamson at Miami University • My students, especially: • Caitlin Finn, Ming Leung, Hannah Naughton, Xiangyu Wang, Andre May • Cole Arora • Funding from: • NC Wildlife Resources Commission • NSF (DEB program) • The Duke Endowment (Duke University) • Paletz Innovative Teaching Fund (Duke University) • Thompson Writing Program (Duke University) Thanks for your attention!

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