Engel, Anja , Heemann, C., Schartau, Markus , Schneider, U., Thoms, S., Delille, B., Jacquet, S., Zondervan, I. and Riebesell, Ulf (2003) Transparent Exopolymer Particles (TEP) production by marine phytoplankton in response to increasing CO2: laboratory and field mesocosm experiments. [Talk] In: EGS-AGU-EUG Joint Assembly. , 06.-11.04.2003, Nice, France .

Abstract

The export of organic carbon to the deep ocean is mediated by sinking of large particles, such as marine snow, the formation of which is enhanced in the presence of transparent exopolymer particles (TEP) . TEP form from dissolved and colloidal polysaccharides by aggregation processes. Especially when running into nutrient limitation phytoplankton organisms are a source of TEP in pelagic ecosystems as the cells release a significant amount of the assimilated carbon in the form of polysaccharides. Because CO_2 concentration influences carbon assimilation rates, we hypothesized that polysaccharide exudation and aggregation into TEP is related to CO_2 concentration under nutrient limiting conditions. We tested this hypothesis in several lab and outdoor experiments with natural populations and cultures of phytoplankton exposed to various levels of CO_2 concentrations. Our results indicate that TEP production increases with CO_2 concentration and provides an enhanced sink for carbon during phytoplankton blooms.

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