Seamounts: a review of physical processes and their influence on the seamount ecosystem

Abstract

Seamounts are large topographic features, which extend a great vertical distance from the seafloor of the world’s oceans. They are defined as having a vertical elevation of more than 1000 m with limited extent across the top summit region. Smaller features, similar in characteristics, but with elevations of 500-1000 m, have been termed knolls, and those less than 500 m hills. In recent years, a large number of seamounts have been discovered, and there are now over 30000 features over 1000m in vertical extent known in the Pacific alone (see Rogers (1994) for references to above). Seamounts may have various shapes – conical, circular, elliptical, or elongated seamounts often known as Guyots and are usually volcanic features. The water depth at which the summit reaches may be important. Shallow seamounts may be thought of those reaching into the euphotic zone, intermediate seamounts with summits below the euphotic zone but within the upper 400 m layer and deep seamounts with peaks below 400 m depth (Genin, 2004). This report reviews the many physical oceanographic processes that occur at seamount features and describes the effect these processes may have on the bio-geochemistry of seamount ecosystems. Section 2 reviews the basic dynamical concepts and models of these processes are described in section 3. Section 4 describes the observations of the different physical processes that have been identified. The interaction between the physical processes and bio-geochemistry are discussed in section 5 and a synthesis summary is presented in section 6. A map showing the location o f the principal seamounts mentioned in this review is given below in Fig 1