Copepod Distribution in Relation to Seasonal Hydrographics and Spatial Structure in the North-western Mediterranean (Golfe du Lion)

Abstract

Copepod abundance and hydrography from the upper 50 m in the Golfe du Lion (NW Mediterranean) were studied during 1986-88. Seasonal distributions of eight genera and 35 species at 87 stations were analysed by means of numerical classification. An obvious distinction can be observed between near-coastal/neritic stations and oceanic stations. Most abundant copepods were epipelagic and non-migrating like: Clausocalanidae, Oithonidae, Paracalanus parvus, Oncaeidae, Centropages typicus and Temora stylifera. Inverse analysis demonstrated (1) High densities for the epipelagic, non-migrating Clausocalanidae and Oithonidae over many clustered station groups. Paracalanus parvus and C. typicus were abundant during the summer sampling periods whereas T. stylifera was abundant in September. Common were some vertical migrators like: Calanus helgolandicus, Pleuromamma gracilis, Candacia armata and Euchaeta marina. (2) Rare, bathypelagic species were collected during the February and July sampling periods in the upper 50 m. In February this synchronized with vertical mixing of the water column, in July with locally upwelled deep intermediate water, remaining below the thermocline. Relatively high mean subsurface temperatures were measured in December and February. Salinities showed a considerable variation in Rhône influence between the different seasons. Species with mainly herbivorous feeding habits were more abundant than those of more diverse omnivorous or carnivorous feeding habits.