Multidisciplinary indicators for confirming the existence and ecological effects of a Taylor column in the Tropical Western Pacific Ocean

Abstract

The Taylor column, a typical hydrological structure around a seamount, can help to explain the high biomass and biodiversity around the seamount. However, it is difficult to observe a Taylor column in the field because it is easy to be destroyed by the change of ocean environment. Fortunately, a Taylor column around the C4 seamount in the Tropical Western Pacific Ocean was identified during our cruise. The existence of a Taylor column was confirmed by multidisciplinary indicators: 1) the theoretical calculation values of Bl and Ro were 4.922 and 0.195, respectively, indicating the environmental conditions were sufficient for a Taylor column to form; 2) the uplifts of isotherms and isohalines indicated the existence of the upwelling around the C4 seamount summit; 3) the Acoustic Doppler current profilers (ADCP) data indicated the existence of an anticyclonic circulation at the water layers ranging from 200 to 300 m. Meanwhile, the Taylor column's ecological effects were obvious around the seamount. The isolines of the nutrients, chlorophyll a and heterotrophic bacteria had uplifts approximately consistent with isotherms and isohalines, indicating they were influenced by the upwelling in this region. Meanwhile, the planar graphs of these parameters in the water column above 200 m showing the values around the seamount were relatively high, indicating the effects of the Taylor column on the enhancement of productivity. These results further confirmed that a Taylor column indeed formed and caused ecological effects in the C4 seamount. Finally, the scope of the Taylor column was roughly estimated based on the Chl a concentrations, which centered around the station O with a radius of 6.1 km.