Midwater tunicates: are they related to the permanent front of the Ligurian Sea (NW Mediterranean)?

Abstract

Submersible cruises in the frontal zone of the Ligurian Sea showed the presence of midwater (400-800 m) populations of a not yet described larvacean species of the genus Oikopleura and of the thaliacean Salpa fusiformis. The vertical stratification of autotrophic and heterotrophic organisms and the occurrence of autotrophic microphytoplankton at aphotic depths suggested that food supply for midwater filter feeders was actively transported by the frontal circulation from the subsurface layers along the inclined isopycnals. Minimum flow velocity for renewal of organic carbon at the midwater stratum was c20 m d-1. -from Authors