Resting stages in a submarine canyon: a component of shallow-deep-sea coupling?

The ecological importance of resting stages in shallow waters is well known , but their presence in the deep sea is practically unrecorded. Samples of sinking particles were collected from April 1993 to May 1994 in and around the Foix Canyon (northwest Mediterranean Sea) using PPS3 sediment traps loc ated between -600 m and -1180 m. Dead and viable organisms were collected, and inorganic empty shells constituted most of the biologically-derived mat ter. Resting stages, considered as POM, had a flux of up to 70 000 items m( -2) d(-1). They were the second most abundant fraction of total POM after t intinnids (mainly represented by empty, chitinous loricas), and first of th e viable POM fraction. Most remained unidentified, but 58 morphotypes were referable to coastal species of Dinophyta, Tintinnina and Calanoida. Restin g stages were rare in samples collected from the open slope adjacent to the canyon. These preliminary data suggest an important role of submarine cany ons in concentrating POM and transferring it from shallow to deep-sea habit ats. Due to their resistance to degradation processes, resting stages are p robably the only POM component that can return to shallow areas by upwellin g currents occurring in the canyon.