The biology of Gammarus (Crustacea, Amphipoda) in the northwestern Atlantic. V. Gammarus oceanicus Segerstråle

Abstract

Gammarus oceanicus is an intertidal species found between Long Island Sound and southern Foxe Basin in the northwestern Atlantic. Fifty percent maturity of the females is attained at 11 and 13.8 mm body length in the January–May and June–August periods, respectively, at Holyrood, Nfld., and at 11.4 and 13.7 mm at St. Andrews, N.B. In the laboratory females matured in the 13th molt at a mean size of 12 mm in an average of 329 and 230 days at 3 and 12 °C, respectively. Females produce successive broods except between August and November when they enter the resting stage. Relatively few young are released in the winter months. Fecundity increases with the size of the female and the large size at maturity, continued growth, and long life give this species a high reproductive potential.