Investigation into the Feeding Ecology of Larval lobster, Homarus americanus, and their prey consumption rate on the copepod Calanus finmarchicus

The pelagic food-web within the Gulf of Maine consists of commercially important invertebrates, such as lobster and crab, which feed on zooplankton during their larval stages. Shifts in zooplankton density and species composition are known to directly impact commercially important fish stocks, such as Atlantic herring, haddock, and cod, but their impacts on lobster populations have received far less attention. Data from the Gulf of Maine demonstrate a recent decline in lobster recruitment despite high spawning activity. Additionally, Carloni et al. (2018) suggests that the decline in lobster recruitment could be due to a decline in their lipid-rich copepod prey, Calanus finmarchicus. In this study, we conducted experiments to investigate the basic feeding ecology of larval American lobster (Homarus americanus) and explore the possibility that early life stages suffer from food limitation in their environment. We investigated the ingestion rate of stage IV lobster feeding on a range of Calanus concentrations. Further, we conducted choice assays to determine if lobster prefer Calanus when other copepod species are present. Our results suggest that larval lobster readily consume Calanus and preliminary observations suggest that they prefer Calanus over other co-occurring prey species. These results will inform future experiments and suggest that a decline in Calanus could be driving reduced lobster recruitment.