Abstract

The surprisingly high species diversity found among the mostly smallbodied invertebrates inhabiting the deep-sea sediment is thought to be maintained by biologically generated habitat heterogeneity and patchy food resources acting in concert with biological disturbance at the metre to centimetre scale or less (Grassle & Maciolek, 1992). Disturbance is thought to thin existing populations, and is followed by recolonisation of the disturbed patch, to that the populations never develop to a full competitive equilibrium before the next disturbance event.

This review focuses on the possible importance of larger, >kilometre scale disturbance, generated by currents at the deep-sea floor. Data on species richness and abundance from quantitative benthic samples from five areas presenting varying space–time scales in hydrodynamic disturbance are reviewed, in order to show that such diffuse disturbance of the sediment community resulting from episodes of high bed flow in the supposedly tranquil physical conditions at the deep-sea bed may be an important structuring agent for the deep-sea benthic community. The first area is located at the High Energy Benthic Boundary Layer (HEBBLE) study site on the Nova Scotian continental rise in the North West Atlantic, where the sediment floor periodically experiences strong flow and massive re-suspension during vorticity-driven ‘benthic storms’ and hence where eddy kinetic energy, KE, is very high in the benthic mixed layer.