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The Effects of Elevated CO2 and UV Radiation on Carbon Cycling in the Microbial Loop: 

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

Slide2: 

Limnology- study of inland waters Lake Tahoe, CA

Slide3: 

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

What is the abiotic environment versus the biotic environment?: 

What is the abiotic environment versus the biotic environment?

Abiotic Environment: 

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

Biomes and Climate: 

Biomes and Climate Temperature (oC)

Slide8: 

Chemical Environment Carbon Cycling Nutrient Cycling

The Carbon Cycle: 

The Carbon Cycle

Distribution and abundance of organisms: 

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

Biodiversity: 

Biodiversity

Law of Tolerance: 

Law of Tolerance

Distribution and abundance of organisms: 

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

Distribution and abundance of organisms: 

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

Distribution and abundance of organisms: 

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

Distribution and abundance of organisms: 

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

Distribution and abundance of organisms: 

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

Slide18: 

Food webs describe the feeding interactions within communities.

My Research…: 

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

Increased UV Radiation: 

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

What does this mean for plants?: 

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 Ambient CO2, 360 ppm Elevated CO2, 780 ppm

The Microbial Loop: 

The Microbial Loop

The Microbial Loop(Simplified): 

The Microbial Loop (Simplified)

Slide25: 

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

Experimental Setup: 

Experimental Setup Quartz tubes Solar simulator

Light Treatments: 

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

Experimental Design: 

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

Bacteria Counts: 

Bacteria Counts

Protist results so far…: 

Protist results so far…

In Summary…: 

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