ABSTRACT
The downward flux of phytodetrital material is recognized as significant pathway of energy to the deep-sea. This material is known to be colonised rapidly by bacteria, flagellates and benthic foraminiferans. In order to evaluate the effect of the seasonal food input on the life history of deep-sea echinoids we have chosen Phormosoma placenta Wyv. Thomson, a non-seasonal breeder, and Echinus affinis Mortensen, a seasonal one, collected during two major deep-sea programmes in the NE Atlantic, viz the Scottish Marine Biological Association (SMBA) in the Rockall Trough, and the Institute of Oceanographic Sciences (IOS) programme in the Porcupine Seabight and Abyssal Plain. Both programmes have temporal and depth related elements.
