PARENT SESSION
Poster Session # 21: Biogeography, Biodiversity, Populations, and Genetics.

Thursday, August 7 Presentation from 5:00 PM to 6:30 PM. SITCC Exhibit Hall B.

Relationships among habitat size, dissolved oxygen, insects, and microbes in artificial treehole communities.

Paradise, Chris^*,1, Harlan, Nicole¹, ¹ Davidson College, Davidson, NC, USA

ABSTRACT- In this ongoing study we are examining interactions among abiotic factors and the diversity of insects and microbes in treeholes, aquatic detritus-based communities. We employed mesocosms (2 depths crossed with 3 diameters) to test the hypotheses that volume, surface area, and dissolved oxygen (DO) affect insect and microbial diversity, and the latter factors affect one another. We sampled habitats for insects, dissolved oxygen, and bacteria. DO should be lower in deep containers with small surface area, which we did find. Large treeholes with a large opening have high DO, and should support high larval densities. Our containers did not show the latter; containers with small diameter and shallow depth had high larval densities, and low DO was correlated with high densities. Densities of common species were positively correlated with one another and with species richness. At the peak of species richness, an interaction between surface area and depth was revealed: some, but not all, shallow treatments had more species than corresponding deep treatments. Results to date indicate that surface area, volume, and resulting DO levels help to shape communities in treeholes, possibly by affecting where females oviposit. Further results from the 2003 season will be presented, as will results from microbial sampling. We predict that as insects consume microbes, microbial diversity increases, which further increases litter breakdown and facilitates insect diversity.

Key words: aquatic community, treeholes, habitat size, detritus processing chain