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Phytoplanktonic dinoflagellates form colonies between vertical ice crystals during the ice-melting season in Lake Baikal, but how the plankton survive the freezing conditions is not known. Here we show that the phytoplankton produces large amounts of dimethylsulfoniopropionate (DMSP), which is best-known as a marine compound. Lake-water DMSP concentrations in the spring season are comparable with those in the oceans, and colony water in ice exhibits extremely high concentrations. DMSP concentration of surface water correlates with plankton density and reaches a maximum in mid-April, with temperature-dependent fluctuations. DMSP is released from plankton cells into water in warm days. DMSP is a characteristic osmolyte of marine algae; our results demonstrate that freshwater plankton, Gymnodinium baicalense, has DMSP-producing ability, and efficiently uses the limited sulfur resource (only 1/500 of sea sulfate) to survive in freshwater ice. Plankton in Lake Baikal do not need an osmolyte, and our results clearly indicate that DMSP plays a cryoprotective role. DMSP, although a characteristic marine compound, could also be an important zwitterion for algae of other boreal lakes, alpine snow, and glaciers.DMSP potentially serves as a form of cryoprotection for freshwater dinoflagellates during the time of ice melting in Lake Baikal although sulfur content of the lake water is much lower than seawater and algae do not need an osmolyte in freshwater ice. [ABSTRACT FROM AUTHOR]

The vapour generation - chemiluminescence (VG-CL) detection system that was designed for this research was used for the measurement of dimethylsulphide (DMS) and its precursor dimethylsulphoniopropionate (DMSP). The present study attempted the development of a highly sensitive, portable and cost-effective detection system based on vapour generation and chemiluminescence for a pilot assessment and determination of DMSP and DMS concentrations in the Gulf of Guinea. The Elegushi Beach and Nigerian Institute of Oceanography and Marine Research (NIOMR) which are parts of the Atlantic Ocean were chosen as designated locations for this study. The average concentrations of DMSP and DMS in the surface seawater at the two locations ranged from 12.4 ± 0.2 to 26.5 ± 0.5 nM, 2.1± 0.0 to 40.9 ± 1.6 nM and 9.7 ± 0.4 to 44.9 ± 0.2 nM, 0 to 35.6 ± 2.3 nM, respectively. This study serves as a baseline measurement of the concentrations of DMS and DMSP in the tropical Atlantic Ocean (Lagos). [ABSTRACT FROM AUTHOR]