Gas-floating aggregates of Antarctic benthic diatoms

Abstract

We report the formation of gas-vesicle stalked aggregates formed by a mucoid-sediment layer colonized by pennate diatoms and occasional centric diatoms. The most frequently occurring diatoms within this layer belonged to Pleurosigma sp., with less abundance in the stalk. Aggregates stayed attached to the sediment up to ten days until the buoyant force was sufficient to release them from the bottom. The structures were observed twice, in outdoor tanks (250 L) containing marine sediments in filtered seawater under natural light cycle and ambient temperature (-1.3 to 0.6 ºC), after 15 days. Whether this mechanism occurs in the field awaits elucidation. However, it stands out as a pathway for benthic diatom dispersion, resuspension and benthic-pelagic coupling for Antarctic coastal systems.