Selective Bivalve Shell Destruction in Marine Environments, A Field Study

Abstract

ABSTRACT Eighty four single valves, equally divided between the bivalve species M. mercenaria, Argopecten i. irradians and Mya arenaria, were submerged for three years in a shallow, low energy, sublittoral environment. Weight changes, modifications in shell characteristics, the growth of attached epifauna, and the effects of boring algae were recorded on a yearly basis. Valves with greater surface area per unit weight suffer a greater weight change, are more subject to breakage, and are more heavily encrusted with attached epifauna than those with less surface area per unit weight. These differences are explained in terms of differential burial; shells with less surface area per unit weight being buried more rapidly than thinner and lighter valves, which are maintained above the ediment-water interface. Solution appears to be the chief destructive agent below the sediment-water interface whereas boring marine organisms are the dominant agent in shell destruction above the interface. Comparison with other environments indicates that shell destruction is 150 to 1000 times more rapid in surf zones when abrasion is the principal destructive agent, than it is in low energy sublittoral environments. The paleoecologic implications of differential shell burial and destruction are examined.