Do invasive and native bivalves compete for food resources? The role of detritus in supporting sustainable aquaculture and invasive species management

Carrying capacity estimates of bivalve aquaculture suggest large production increases are possible based on abundant detrital resources. However, the role of detritus in bivalve diets is poorly understood and detritus in models is usually poorly defined.

With calls to increase bivalve production to meet sustainable food needs laid out in Agenda 2030, a more thorough understanding of what ecosystem resources support bivalve aquaculture is needed to ensure the industry develops sustainably.

Additionally, with distributional overlaps between native European oysters and the invasive Pacific oyster in Sweden, there is a need to understand how oysters may compete for food.

The proposed study aims to elucidate what role detritus plays in the diet of mussels and oysters and the degree of dietary overlap among them on the Swedish west-coast.

Using a combination of bulk stable isotopes (δ13C and δ15N), fatty acid biomarkers, and amino acid δ15N analysis, we will compare the diet composition, reliance on detritus, degree of dietary overlap, and trophic niche among three species of bivalves (Mytilus edulis, Ostrea edulis, and Magallana gigas) cultured in areas with low and high detrital abundance over a period of two years.

By investigating dietary overlap and detritus use among bivalves, this study aims to support sustainable food production by improving future carrying capacity estimates and generating growth and quality data for Swedish bivalve growers.