PTEROPODS ARE UNDERVALUED CONTRIBUTORS TO ARAGONITE FLUX IN TROPICAL GYRES

Pteropods are a large component of the animals routinely caught in sediment traps at 3000m at the NOG observatory in the North Atlantic Oligotrophic Gyre and at the SOG observatory in the South Atlantic Oligotrophic Gyre. Sediment traps have been used to collect downward settling material at NOG and SOG since 2008. Pteropods have been identified and removed from the samples during processing in line with best practice. Some of these animals maybe opportunistic swimmers, but some are most definitely broken and should be considered as a component of the downward particle flux.

Samples from both locations demonstrate a sustained and sometimes seasonal flux of pteropods to the deep ocean interior. In gyre regions with low levels of particle flux compared to temperate regions, the additional mostly inorganic material supplied in the form of pteropod shells represents a large proportional increase.

Our data set from both northern and southern Atlantic gyres demonstrates due consideration should be given to the importance of pteropod flux and the contribution this makes to the biological carbon pump.

These observatories at 23°N 41°W and 18°S 25°W, are part of the FixO3 open observatory network and are supported by NOC and NERC. Analysis of the first three years of each observatory are now yielding new insight on these large and poorly sampled areas of the open ocean.

Key words: pteropods; aragonite; sediment traps; NOG SOG; FixO3; biological carbon pump; biogeochemical cycles; Tropical Atlantic Gyres.