Measuring secondary production of zooplankton: Biological rate measurements are key to developing realistic and accurate food-web models. Although oceanographers have routinely measured the primary production of phytoplankton since the 1960s, comparable measurements of in situ community-level production by zooplankton remain surprisingly rare. Our lab has implemented a novel enzyme-based assay to quantify the in situ production of crustacean zooplankton. When coupled with estimates of primary production, this also enables us to derive rate-based estimates of trophic transfer efficiency – another fundamental variable in food-web models for which direct field-based estimates are almost non-existent.
Anthropogenic impacts on marine ecosystems: As the global extent of human impacts on the ocean continues to grow, so too does the list of ways that we interfere with the structure and function of marine ecosystems. In recent years, my lab has investigated aspects of the ecology of invasive marine species, the potential impact of microplastics on marine food webs, the effects of ocean acidification on the growth and survival of zooplankton, and climate-related shifts in the composition of zooplankton communities.
Feeding, growth and survival of larval and juvenile fish: Larval fish play a pivotal role in marine food ecosystems. As key consumers of zooplankton, they represent a trophic bridge between lower and higher trophic levels in marine food-webs. Consequently, variability in their growth and survival dictates interannual variability in patterns of recruitment to adult fish populations. To explore such linkages my lab employs a wide range of approaches including larval gut analysis, otolith microstructure, lipid and fatty acid profiles, stable isotopes, and RNA:DNA ratios.
Physical-biological coupling in marine food-webs: Spatiotemporal variability in the
productivity of planktonic marine ecosystems is often driven by coupling between
physical and biological processes. At
mesoscales, I have explored this idea as it relates to the high biological
production often observed at shallow seamounts.
At smaller scales, I have used field-based studies to demonstrate the
importance of microscale turbulence to the feeding success and growth of
individual larval fish, and (under some circumstances) the potential for
biologically-generated turbulence to contribute to ocean mixing.