MEPS prepress abstract  -  DOI:

Transparent exopolymer particles in the deep ocean: Full-depth distribution patterns and contribution to the organic carbon pool

Yosuke Yamada*, Taichi Yokokawa, Mario Uchimiya, Shigeto Nishino, Hideki Fukuda, Hiroshi Ogawa, Toshi Nagata


ABSTRACT: Transparent exopolymer particles (TEP) play important roles in marine biogeochemical cycles. However, limited data are available regarding the TEP distribution in meso- and bathypelagic oceans. We examined the full depth distributions of TEP in the slope region of the western Arctic Ocean, and subtropical and equatorial regions of the Pacific Ocean. Chlorophyll a concentrations in the euphotic layer were similar (range, 0.1–1 μg L1) in these two regions. TEP concentrations were 1.3–5.4 times higher (depending on depth) in the Arctic Ocean than in the Pacific Ocean. In the Arctic Ocean, TEP concentrations decreased with depth and were positively correlated with POC and prokaryotic parameters (abundance and production). In contrast, in the Pacific Ocean, TEP were distributed uniformly with depth and were uncoupled from POC and prokaryotic parameters. The estimated amount of carbon associated with TEP (TEP-C) exceeded that of POC in the mesopelagic layer of both regions (the TEP-C concentrations were 2–3 times higher than the concentrations of POC) and in the bathypelagic layer of the Pacific Ocean (the TEP-C concentrations were 6 times higher than the concentrations of POC). Our results suggest that TEP are a dynamic and large component of organic carbon pool in the ocean interior, influenced by vertical transport, in situ prokaryotic production, and the self-assembly of polymeric precursors.