Temporal population structure of deep-water cumaceans from the western Mediterranean slope

Abstract

Comparative biological data on the dominant cumacean species in the deep western Mediterranean were obtained from time-series material along a wide bathymetric gradient (389–1808 m).A total of 35 samples were obtained during nine sampling cruises carried out between 1989 and 1994 in the Catalan Sea. Species inhabiting the upper slope (down to around 500 m; i.e. Diastyloides serrata (G.O. Sars, 1865), Leucon macrorhinus (Fage,1951), Leucon siphonatus (Cal0man, 1905), and Leucon affinis (Fage, 1951)) presented wider reproductive periods than deeper species dwelling on the middle and lower slope ( Leucon longirostris (Caiman, 1906), Makrokylindrus longipes (G.O. Sars, 1871), Cyclaspis longicaudata (G.O. Sars, 1864) and less clearly Platysympus typicus (G.O. Sars, 1869)). Among these deeper species, recruitment was limited to the late winter-spring and may be synchronized with input to the bottom of phytodetritus from the euphotic zone. For Leucon longirostris, the most abundant species in this study, breeding Y and adult ' were at maximum density in summer, while preparatory Y also increased in number from late winter to summer, decreasing later during autumn. Vitellogenic oocyte growth also seemed to coincide with the phytodetrital peak for this species.