Physical processes and seamount productivity

Abstract

A brief review is given of the physical dynamics that occur at seamounts and the implica-tions of these dynamics for seamount productivity highlighted. Several physical seamount characteristics, stratifi cation and oceanic fl ow conditions interact to provide a number of different local dynamic responses at a seamount. These include Taylor Columns or Cones, doming of density surfaces, enclosed circulation cells and enhanced vertical mixing. Due to oceanic background fl ow variability, it is likely that the localised seamount dynamics, and resultant bio-physical interaction processes; will also be variable. This makes quanti-fi cation of an ‘idealised’ response of a particular seamount to the impinging fl ow regime diffi cult. It has been widely accepted that dynamics at seamounts generate conditions such as increased vertical nutrient fl uxes and material retention, to promote productivity that fuels higher trophic levels. To date, however, there has been little consistent concrete evidence for this in observations. This is likely due to the non-steady background oceanic forcing which may disrupt the ‘idealised’ response, such as Taylor Cones and circulation cells generated at the seamount. In addition, the seamount may shed passive tracers such as chlorophyll downstream, providing a source of oceanic bio-physical patchiness in the surrounding ocean. Such variability provides a challenge for the environmental management of seamounts.