64PE373 - Diary 3

Climate Change and the Sea between lands: “Mediterranean Sea”
In the Mediterranean sea including, the effects of climate change are likely to be more apparent earlier than in other more open oceans and (Coll et al.,2010). The Mediterranean Sea is, in many ways, a miniature ocean. What makes the Mediterranean Sea very useful for climate change research is that its time scale is much shorter than for the global ocean, with a turnover of 60 years, which means the time scale of a human lifetime. Thus, the Mediterranean Sea is a laboratory-type environment for documenting changes within it and for understanding the role of key processes involved in climate change for making inferences on processes occurring also at the global scale.

It has deep water formation varying on inter-annual time scales and a well-defined overturning circulation. Over recent decades, significant changes in the deep water have been observed both in the eastern basin (Roether et al., 1996) and in the western basin (Schroeder et al., 2012).. It is now realized that the “conveyor belt” circulation in the entire Mediterranean is undergoing change, as evidenced by increases in deep water temperature and nutrient concentrations. Considering the fact that nutrient concentrations have greatly been influenced by dust deposition due to the poorness of freshwater loads, the trace metals (particularly iron) seems to play more critical role in phytoplankton production. Furthermore, abrupt changes in surface circulation and water mass have been recognized on decadal time scales, triggering series of modifications in the hydrology and dynamics of the entire Eastern Mediterranean, with possible influence on the Mediterranean Sea outflow in the North Atlantic Ocean.
The Black Sea as a part of the Mediterranean system, offer some additional experimental opportunities that provides observation chances of alterations within again in the time scale of a human lifetime. Considering its restricted vertical mixing, anoxic basin, large freshwater input and high biological production trapped in a thin layer of upper ~100 m, the behavior and fate of ecosystem processes have their quite unique pattern which can provide us important clues for understanding the variation mechanisms or factors effecting these processes. For instance; In spite of all those alterations in these land-locked seas, their subsequent evolution and likely impacts on the regional ecology, particularly planktonic food web structure, have remained largely uncertain.

It is therefore that investigating traces metals, particularly with a research vessel like the RV Pelagia is very important. Its ultraclean sampling system provides invaluable chance for researchers to deal not only with the chronical contamination problem, but also with insufficiency in sample volumes. I wish that RV Pelagia finds her way to continue her visits to these land-locked seas with a reasonable periodicity in order to improve and strengthen the findings that enable us to answer some questions on some climate changes related alterations in marine ecosystems.

Kemal Can Bizsel (Dokuz Eylul University, Institute of Marine Sciences and Technology)