Baltimore Ecosystem Study Institute of Ecosystem Studies

2017 BES Annual Meeting Presentation and Poster Abstracts

What are the independent and interactive roles of consumer dispersal and environmental constraints on ecosystem function in experimental ponds?
Voelker, Nicole
Co-Authors: Nicole Voelker Christopher M. Swan

Abstract: The processes and mechanisms shaping communities are key components in determining biodiversity patterns (Chase, 2003). A metacommunity approach was used to investigate the independent and interactive roles of dispersal and environmental constraints on biodiversity patterns and ecosystem function in experimental ponds designed to reflect stormwater pond habitats in the Baltimore metropolitan hydroscape. We performed a full factorial manipulation of local and regional constraints and estimated how benthic macroinvertebrate communities responded and the rate of carbon processing. We hypothesized that there will be a decrease in the rate of carbon processing in ponds experiencing elevated chloride levels, despite high rates of dispersal. We predicted that ponds experiencing elevated chloride levels will have lower alpha and beta-diversity compared to ponds experiencing ambient levels of chloride. We found that elevated chloride levels and an interaction between chloride level and dispersal rate lead to a significant decrease in litter decay rates (p=9.55e-13, p=2.02e-05, respectively). We also found significant shifts in community composition in elevated chloride treatments compared to ambient chloride treatments (p=0.006) and a significant effect of chloride on community dispersion or beta-diversity (p=0.011). We found no significant effect of dispersal on community composition. Chloride may act as a strong environmental filter, preventing the persistence of rare species or intolerant species, despite a high dispersal rate. If the benthic macroinvertebrate community becomes depleted or homogenized in ponds experiencing elevated chloride, the contribution of the macroinvertebrate community to the rate of litter decomposition may be decreased.