Biometry of brooding in seven species of amphipod (Crustacea) from the Clyde Sea area

Abstract

Brood size was found to be correlated linearly with female body length in all species studied, except Ampelisca macrocephala, which is usually a single brooded species. Of the six multi-brooded species, Lembos websteri, Stegocephaloides christianiensis, Echinogammarus pirloti and Gammaropsis nitida produced small numbers of large eggs in the winter and large numbers of small eggs in the summer. In Bathyporeia pilosa larger numbers of smaller eggs were produced by the overwintering generation. In Corophium bonnellii, both maximum and minimum brood sizes were produced by the summer generation. The largest broods relative to female body size were produced by the smaller species. In L. websteri, C. bonnellii and B. pilosa mean female size was smaller in the summer than the winter generation.