Cycle de développement de <i>Leucon nasica</i> (Crustacea, Cumacea) dans la nappe glaciale circalittorale de la baie des Chaleurs, golfe du Saint-Laurent, en 1968 et 1969

Abstract

Macer–GIROQ suprabenthic sled tows have brought 166quantitative samples taken bimonthly from June to October 1968–1969 at two monitoring stations (depths 110–119 m) on homogeneous muddy bottoms inconstantly cold (0.1–1.5 °C) water. The population is dominated by immatures and subadults having a rather stable density of about 0.5–1.0 individuals/m 3 . Mature male densities, marked in July–August by a strong peak mostly at dusk and at night, indicate nuptial swarmings. Females bear an average of 30–60 eggs, 0.40–0.44 mm in size. Fertilization and release of mancas occur mostly in July–August, apparently synchronized with probable food inputs to the bottom from the spring (May) bloom of surface primary production. There are eight postmarsupial instars in both sexes, and sometimes one postadult in females. Maturity is reached after 3 years at 11.3–11.4 mm in length. Mature males die after fertilization. Growth in length is about 24–25% per molt, but lacking at the maturation molt, and flexible in the late immature male.