Ecological impact of magnetotactic bacteria across redox gradients in the Baltic Sea (BALTICMAGX)

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Magnetotactic bacteria live in marine and limnic environments in the chemocline transition zone between oxygenated and sulfidic waters. Here, they move along the various chemical horizons that make up the chemocline, with the aid of chemical sensing and the nanometer-sized ferromagnetic crystals that they mineralize within their cell, called magnetosomes. Magnetotactic bacteria are a diverse and abundant group of aquatic bacteria, however, only a few studies have so far addressed their ecological importance in pelagic environments. Recent studies in Lake Pavin and the Black Sea revealed that pelagic magnetotactic bacteria may accumulate large amounts of phosphatein the form of polyphosphate . For the Black Sea, it was shown, that they may shuttle within the suboxic water masses accumulating phosphate at the upper zone and releasing it at depth. This pumping of phosphate away from surface waters is preventing eutrophication and may be a reason for the oligotrophic state of the Black Sea. A preliminary survey in the Baltic Sea revealed that also here magnetotactic bacteria can be found in the water columns of the deep sulfidic basins. This project aims to describe and quantify these populations of magnetotactic bacteria and to reveal their possible influence on phosphorus cycling in the Baltic Sea.