Ecological Interactions of Shellfish Aquaculture

Project Description

Most existing shellfish aquaculture models were developed for implementation at the production or farm scale, neglecting all trophic levels equal to or higher than bivalves. This approach is useful on a farm scale, but shortsighted for ecosystem management, where several user groups may depend on the stability and sustainability of the entire system.

An ecosystem approach to model bivalve aquaculture and associated carrying capacity issues has been developed using Ecopath, a mass-balanced food web model. A food web model of Cobscook Bay, ME (Bioregion 3) was extended and improved to simulate the effects of aquaculture enhancement under different food web configurations representing future climate conditions. For example, different food web configurations were represented in each model by iteratively increasing and decreasing biomasses of certain species groups. Particular focus was placed on the biomass of invasive green crabs, zooplankton, and phytoplankton in the food web models due to the documented changes in these species.

The advantage of using a food web modeling approach is each of these changes can be examined independently of all other changes happening simultaneously in a single bay. A second phase of this project extends the effort to Penobscot Bay (Bioregion 2). Results will be compared against results from Cobscook Bay and an earlier study performed using Ecopath in Saco Bay (Bioregion 1).

Results and Accomplishments

Using Ecopath, researchers have created a static mass balanced food web model for Cobscook Bay. With this model, bivalve shellfish carrying capacity has been estimated. The existing model was used to examine climate change scenarios considering OA and temperature change. Results from the Cobscook Bay ecosystem were presented at the Ecological Society of America (ESA) conference in Portland, Oregon, in August 2017. The research team is now refocusing this effort to assess Penobscot Bay in the midcoast region.

Summary of Data Being Collected

Data	Type	Quantity	Location
Literature reviews of existing species, biomass and vital rates	Literature Review	NA	Published manuscripts
Model generated data from scenario testing	Model-generated output on estimated species biomasses	Three scenarios tested in 2016	Modeling Cobscook Bay