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