Video of a plankton community enclosed in a “Kiel Off-Shore Mesocosm for future Ocean Simulations” (KOSMOS) during a study in Tvärminne Storfjärden (Finland) 2012

Abstract

In June 2012 we deployed six 19 m long KOSMOS units for 8 weeks in the Tvarminne Storfjarden (59° 51.5’ N, 23° 15.5’ E), an open archipelago area on the south-west corner of Finland, in order to study the influence of ocean acidification on the succession of a plankton community under in-situ conditions in the Baltic Sea. At the beginning of the study (18th of June), we mounted an underwater camera on a diving torch and slowly lowered this setup to a depth of approximately 18.5 m. The video during camera descent shows the post-spring bloom plankton community that we studied within the KOSMOS system. In contrast to mesocosm studies in other regions, the plankton community was less lively: there was a comparatively high number of organic matter aggregations and low abundance of zooplankton. The conical mesocosm sediment trap can be seen at the end of the video in 19 m water depth. The results of this mesocosm study are presented in Biogeosciences in a Special Issue 'Effects of rising CO2 on a Baltic Sea plankton community: ecological and biogeochemical impacts', currently in Biogeosciences Discussion. The video can be downloaded on OceanRep but is also available on the KOSMOS channel of the streaming platform YouTube.