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A research cruise has conducted the first coordinated study of the impact of acidification and global warming and other direct anthropogenic pressures on the Mediterranean Sea

June 6, 2013

MedSeA_logo_smallAn international research team working on the MEDSEA project, coordinated by Patrizia Ziveri, of the UAB, in collaboration with IMEDEA, the Institute of Marine Sciences (ICM-CSIC), the University of Cadiz, MedSeA Partners, the Instituto Español de Oceanografía, and the GEOTRACES international programme, has just returned from a research cruise to survey the current state of the Mediterranean Sea in relation to the elevated atmospheric CO2, and also to detect other anthropogenic impacts on the sea, such as the distribution of micro-plastics. The team collected a large number of samples of both surface and deep seawater to characterize the CO2 system and other chemical compounds in the water, and their impact on certain organisms and biogeochemical processes.

 The sampling included aerosol collection, plankton tows and detailed water column and sediment samplings, in addition to natural and artificial radioactive isotopes and trace elements dissolved in the seawater. Four sea robots (bio Argo floats, NAOS project) carrying miniature sensors were deployed at different locations in the Mediterranean to continue collecting data (on water temperature, nutrients, salinity, chlorophyll, etc.) over the coming months.

 Among the expedition’s first findings, the researchers highlight the abundance of small pieces of plastic debris floating in the open sea. This is the first time a survey of this kind has been conducted in the whole Mediterranean basin and the researchers were surprised to find so many micro-plastics far from the coast.

 Another finding was that of large jellyfish blooms in the open sea, in what is the first expedition to have taken samples on a Mediterranean-wide scale. In the western basin the researchers found large numbers of the jellyfish Pelagia noctiluca (mauve stinger) and Velella velella (by-the-wind sailor, or purple sail). The collected data will help determine the causes of these high densities and whether they could be related to anthropogenic environmental pressures. There is currently much speculation on this and the most likely causes are over-fishing and the consequent lack of predators, as well as the rise in sea surface temperature. First experimental results on the impacts of ocean acidification on jellyfish showed the resilience of these species to these conditions. Further research is necessary to confirm this, however, and this expedition is therefore highly important.

 This oceanographic cruise took place on board the research vessel Ángeles Alvarino, of the Instituto Español de Oceanografía (IEO), co-funded by FEDER, in collaboration with the Marine Ecology Unit (UTM-CSIC). The cruise’s outward leg was from Cadiz to Heraklion (Crete), beginning on 2 May, and the return leg was from Heraklion to Barcelona.

López O,  Universitat Autònoma de Barcelona. Press release. 03/06/2013

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