Global distribution of exopolymeric particles in the ocean

Abstract

Transparent exopolymeric particles (TEP) are gel-like substances released by phytoplankton and heterotrophic prokaryotes, which play a relevant role in carbon export to the ocean floor. Here, we describe the vertical and geographical distributions of TEP in the Atlantic, Indian and Pacific Ocean during the >Expedition Malaspina 2010>. In surface waters, TEP showed an average concentration of 15.0 µg of xanthan gum equivalent per liter (µg XG eq L-1), ranging from 0.2 to 168.9 µg XG eq L-1. In the Atlantic Ocean, there was a significant increase of TEP close to the Benguela Current. In the Indian Ocean, TEP concentrations were higher near the South African and Australian coasts. In the Pacific Ocean, TEP concentrations were higher than in the other oceans and increased significantly near the `Costa Rica Dome´. In the middle of the Atlantic and Pacific Gyres TEP were relatively higher suggesting an accumulation due to convergence of warm surface water, or higher release of phytoplankton due to extreme sunlit conditions. Overall, we found lower and mostly uniformly distributed TEP concentrations in the meso- and bathypelagic zones, ranging from non- detectable to 62.8 µg XG eq L-1, with an average concentration of 5.5 µg XG eq L-1. However, in the subequatorial bathypelagic zone of the Pacific Ocean we observed concentrations comparatively higher that could be related to an intense prokaryotic activity observed in these deep waters