Comparative Ecology, Life Histories, and Behaviour of Intertidal Sand-Burrowing Amphipods (Crustacea: Haustoriidae) at Cape Cod

Abstract

The ecology of three species of Haustoriidae (Crustacea: Amphipoda) found at Sippewissett Creek, Cape Cod, Massachusetts, and life cycles of two of them are described. The species are Haustorius canadensis Bousfield, Neohatistorius biarticulatus Bousfield, and Acanthohaustorius millsi Bousfield. The first two species are essentially intertidal and the last is essentially subtidal. Haustorius canadensis and N. biarticulatus are annual breeders; the first ovigerous females appeared when the water temperature reached 14 C. The sex ratios were 1:1 for H. canadensis and 3 ♂:2♀ for N. biarticulatus. The relationship between brood size and dry body weight was linear for both species. The weight of a brood of eggs ranged from 8% of the dry body weight for a female N. biarticulatus to 16% of the weight for a female H. canadensis.Haustorius canadensis and N. biarticulatus were, in the main, separated both vertically and horizontally in the sand, and A. millsi was separated horizontally from the other two species. This is believed to be a major factor in reducing competition for food between the species. The species all appeared to feed on similar types of food, with the only observable difference in the gut contents of H. canadensis and N. biarticulatus being the size of the food particles eaten.