PELAGIC-BENTHIC COUPLING IN THE BAY OF FUNDY

Bivalve reefs are important in pelagic-benthic coupling and, in order to assess these linkages quantitatively, it is necessary to obtain acc urate maps of reef biomass and production. Presented here is a prelimi nary attempt to use modern surficial geological techniques, including sidescan sonar and a high resolution seismic reflection system to map the distribution of bivalve reefs in the Bay of Fundy. Acoustic techni ques were groundtruthed with a 0.5-m(2) video grab. The grab jaws coul d be hydaulically closed from the deploying vessel on the basis of a v ideo view of the sediment from a camera focused between the grab jaws. Sampling was limited to the upper Bay of Fundy where five geological provinces were recognized. Preliminary results show that horse mussels are limited to the harder, more stable sedimentary provinces (gravel/ cobble and mottled gravel), but also to an intermediate province: sand with bioherms. The latter are raised features formed by the horse mus sels on megarippled sand which are long and thin, and flow-parallel st ructures covered with epifauna. Although positive, the present data ar e insufficient to conclude whether acoustic methods can significantly improve on conventional benthic grab sampling methods to map benthic p roduction.