The Effects of Elevated CO 2 and UV Radiation on Carbon Cycling in the Microbial Loop

1. The Effects of Elevated CO2 and UV Radiation on Carbon Cycling in the Microbial Loop Dina M. Leech Dept. of Environ. Sciences and Engineering UNC-Chapel Hill Whale Bone Bay, Bermuda

2. Limnology- study of inland waters Lake Tahoe, CA

3. COMMUNITY Species diversity Abundance Distribution Predator/prey interactions ECOSYSTEM Energy or Carbon cycling Nutrient cycling Ecological Stressors and Aquatic Ecosystems Lake Tahoe, CA USA

4. What is the abiotic environment versus the biotic environment?

5. Abiotic Environment • Climate • Summation of weather conditions over long period of time • Temperature • Moisture • Wind

6. Biomes and Climate Temperature (oC)

8. Chemical Environment • Carbon Cycling • Nutrient Cycling

9. The Carbon Cycle

10. Distribution and abundance of organisms A species’ tolerance for the abiotic environment is one of many factors that affect where it lives and how common it is

11. Biodiversity

12. Law of Tolerance

13. Distribution and abundance of organisms • A species’ tolerance for the abiotic environment is one of many factors that affect where it lives and how common it is • Some species are widespread and common pigeons

14. Distribution and abundance of organisms • A species’ tolerance to the abiotic environment is one of many factors that affect where it lives and how common it is • Some species are widespread and common • Other species are localized and rare Marine Iguana

15. Distribution and abundance of organisms • The distribution and abundance of species changes over time • Some species decline in abundance and extent of geographic range

16. Distribution and abundance of organisms • The distribution and abundance of species changes over time • Some species decline in abundance and range • Other species increase in abundance and expand in range

17. Distribution and abundance of organisms • The distribution and abundance of species changes over time • Some species decline in abundance and range • Other species increase in abundance and expand in range • The causes of these changes include geological change, climate change, and “anthropogenic” factors

18. Food webs describe the feeding interactions within communities.

19. My Research… • Increases in atmospheric CO2 concentrations • Effects on global climate Manoa Record

20. Increased UV Radiation ftp://jwocky.gsfc.nasa.gov/pub/eptoms/images/global/y2003/FULLDAY_GLOB.GIF

21. What does this mean for plants? • Plants growing under elevated CO2 are higher in lignin content, shifting the C:N ratio • Basically, this plant material is tougher to break down and less nutritious to microbes • HOWEVER, UV can help the microbes by aiding in the degradation of this plant material Elevated CO2, 780 ppm Ambient CO2, 360 ppm

23. The Microbial Loop

24. The Microbial Loop(Simplified)

25. Effects of Climate Alterations on Energy Transfer within the Microbial Loop DOC from plant leachate Bacteria Protists Rotifers

26. Experimental Setup Solar simulator Quartz tubes

27. Light Treatments • Quartz- UV-B, UV-A, Visible • Mylar- UV-A, Visible • Acrylic- Visible • Exposed for 6hrs

28. Experimental Design • Inoculate the DOC treatments with bacteria • Grow the bacteria for 3 days • Sample every day to observe changes in abundance • On the third day, feed the bacteria to protists (i.e. flagellates and ciliates) • Grow the protists for a few weeks • Watch how community changes

29. Bacteria Counts

30. Protist results so far…

31. In Summary… • Abiotic factors and the physical environment vs. biotic factors • Organismal tolerance • Abundance and distribution patterns • CO2 and UV radiation as ecological stressors