Distribution of Shell-Boring Polychaetes at Shellfish Aquaculture Sites Along the Northeast Coast of the US
Coastal shellfish aquaculture has expanded substantially in recent years in Maine and New England as traditional wild fishery stocks have declined. As shellfish aquaculture has expanded, producers have become more concerned about marine worm pests (i.e., polychaetes) that infest cultured bivalves. In particular, worms from the genus Polydora (also known as “polydorids”) burrow into oyster and scallop shells where they feed and deposit mud. Bivalves cover over the muddy burrows creating blisters that can decrease their market value and hinder growth. Farmers and researchers have identified methods to control infestations of P. websteri, one common species of shell-boring worm. However, recent surveys have identified the presence of additional species of shell-boring polychaetes among shellfish aquaculture sites in New England. Whether the same control measures will work for all species depends on the ecology, reproductive biology and distribution of these new species. The goal of my project was to determine the distribution of different shell-boring polychaetes at bivalve aquaculture sites in northern New England. I used light and scanning electron microscopy to identify polychaete worms from the shells of bivalves sampled from twelve shellfish farms across the region. Using molecular biological tools, I confirmed the identity of these species. In addition to P. websteri, a species commonly found in New England, I observed P. onagawaensis, an introduced species that previously had only been observed on shellfish farms in Japan.