Growth and population structure in two species of bivalves (Nuculanidae) from the deep sea

Abstract

Numerous specimens of Nuculana pernula and Yoldia thraciaeformis (Bivalvia: Nuculanidae) were collected from depths of 895 to 1500 m in the Northwest Atlantic Ocean off Newfoundland. Sizes attained by both species approach or exceed previously recorded maximum lengths. The populations are dominated by large individuals. Little overlap in lengths between the cohabiting species is observed. Boring gastropods and benthic fish are identified as predators of small bivalves at these depths. Rapid growth rates early in life, heavy predation on young individuals, and size-related mechanisms reducing niche overlap are possible explanations of the observed size structure.