Bridging the Great Disconnect: Linking the pelagic food web to larval recruitment

Funding agency: Maine DMR Lobster Research Collaborative and National Sea Grant


Richard A. Wahle, University of Maine

David M. Fields, Bigelow Laboratory for Ocean Sciences

Joshua Carloni, New Hampshire Fish & Game Department

Burton Shank, NOAA Northeast Fisheries Science Center

Paul Geoghegan, Normandeau Associates, Inc., Bedford, NH

Graduate Student Investigators:

Alex Ascher, University of Maine, School of Marine Sciences

The disconnect between high egg production rates and low numbers of settlers is enigmatic. As part of a larger multifaceted effort to elucidate the drivers of recent declines in early benthic lobster recruitment, the proposed study focuses on the potential role of changes in the pelagic foodweb.

Our study aims to provide critical insight into the interaction between lobster larvae and components of the zooplankton assemblage through retrospective analysis of existing time series, enhanced field sampling, and stage specific gut analysis of lobster larvae collected in the field.

Through a time series analysis, we will be investigating the spatial and temporal dynamics of lobster settlement and zooplankton assemblage, and identifying links between zooplankton regime shifts and lobster settlement success. We will also be investigating how the phenology of zooplankton and lobster larvae changed over the time series and if there is any evidence in the phenology of predator and key zooplankton prey.

Our study also aims to do enhanced field sampling and in situ diet analysis. Field sampling will be done to measure vertical distribution of lobster larvae at specific stages relative to zooplankton. We will also be performing diet analysis techniques on larvae collected from the field. Little is known about the natural diet of lobster larvae, however, through dissections and eDNA, we hope to see which zooplankton species are being consumed and at which stage.  We also aim to measure the nutritional status of diet on larvae and see if this varies over the course of the season.






Images: (right) copepod species in larval gut, (middle) larval stomach, (left) larval stomach visible in stage I