Ecosystem functioning in northeast pacific soft-sedimentary habitats: the roles of species diversity, functional diversity, and environmental variables.

Abstract

Previous studies indicate a central role for biodiversity and environment in marine ecosystem functioning, raising concerns about the potential consequences of biodiversity alteration. By combining marine biology and biogeochemistry approaches, and field and laboratory-based approaches I provide new information on biodiversity and environmental contributions to important ecosystem functions such as benthic flux variation and organic matter degradation. Using published benthic flux rate measurements and available environmental variables, I created global models and maps to identify predictors of benthic fluxes of oxygen and nutrients. By performing incubations of intact sediment cores and measuring benthic flux rates, I determined that, of the environmental variables examined, bottom water properties, organic matter quality, and sediment characteristics best explained benthic flux variation. By adding functional and species diversity metrics, I demonstrated that biodiversity and environment contribute about equally to these functions, and that functional richness was the most important predictor of benthic flux variation and organic matter degradation. In experimental incubations where I added phytodetritus to intact sediment cores, I determined that higher taxonomic diversity, and densities of detritivores and omnivores explained higher benthic flux rates in enriched sediment cores. These results point to the combined importance of biodiversity and environment in controlling ecosystem functioning and illustrate the need to combine established and novel approaches to evaluate more fully the consequences of anthropogenic impacts, such as biodiversity alteration and environmental change for ecosystem functioning