Food webs and species biodiversity of the fouling community associated with bivalve aquaculture farms compared to analogous non-farm structures

Abstract

Bivalve aquaculture farms are an integral part of the surrounding coastal marine ecosystem and associated food webs. What is not well understood is how these anthropogenically manipulated, dense, single-species cultures influence species trophodynamics in the coastal ocean. Fouling macrofauna biodiversity, macroalgae biomass, sediment, and food web structure were studied at two blue mussel (Mytilus edulis) floating raft rope-culture aquaculture farm structures and two analogous floating dock structures without mussels in Casco Bay, Maine, USA during the summers of 2016 and 2017. Shannon Wiener diversity index of macrofauna was variable across structures compared depending on month. Macroalgae biomass was significantly higher on farm structures exclusively due to green macroalgae. There was no shift in food web structure determined by stable isotope analysis (δ13C and δ15N) and Layman metrics. This study is an initial step critical to assessing interactions of bivalve farms with coastal food webs.