How Phytoplankton Membranes Cope With Steep Ionic Strength (Salinity) Gradient?

Blazenka Gasparovic1,2, Tihana Sesar1, Milan Cankovic2, Zrinka Ljubešić3, Enis Hrustić4, Zhuoyi Zhu5, Ruifeng Zhang5 and Jinzhou Du5, (1)Ruđer Bošković Institute, Division for marina and environmental research, Zagreb, Croatia, (2)Ruder Boskovic Institute, Division for Marine and Environmental Research, Zagreb, Croatia, (3)University of Zagreb, Faculty of Science, Department of Biology, Zagreb, Croatia, (4)Institute for Marine and Coastal Research, Dubrovnik, Croatia, (5)East China Normal University, Shanghai, China
Abstract:
We report on phytoplankton accommodation on stressful conditions being steep ionic strength, i.e. salinity, changes, the conditions regularly found in the estuaries. We aimed defining how lipid composition of phytoplankton membrane structure is accommodated to prevent spontaneous osmosis. Salinity-dependent lipid profiles for particulate lipid extracts from blooming periods of the two opposing estuaries: eutrophic and polluted Wenchang River Estuary and pristine oligotrophic/mesotrophic Krka River Estuary were characterized by thin layer chromatography (TLC). The composition of phytoplankton pigments which was analyzed by high performance liquid chromatography. Domination of pigment Fucoxanthin in both estuaries indicates diatoms were major blooming group. While total particulate lipid concentration was almost an order of magnitude higher in the Wenchang River estuary (on average 238 µg/L) than in the Krka River Estuary (on average 36 µg/L), the lipid composition was similar. This implies that salinity stress is the main influential factor on phytoplankton lipid composition rather than availability of nutrients. Details on the lipid composition that follow salinity changes will be discussed.
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