engleski

Muggiaea atlantica: an Atlantic indicator of hydroclimatic changes in the Mediterranean

The geographical expansion of the calycophoran siphonophores (Cnidaria) Muggiaea atlantica recorded by long-term monitoring in the Ligurian Sea and Adriatic Sea suggests that this species is able to track hydroclimatic changes in the Mediterranean basin. The appearance and increasing dominance of the atlantic M. atlantica in comparison with the mediterranean co-generic M. kochi has been related to low water temperatures recorded in the 1980s in the Ligurian Sea and in the middle 1990s in the Adriatic Sea. Such hydrological changes were associated to large-scale hydroclimatic fluctuations, i.e. the North Atlantic Oscillation (NAO) and Eastern Mediterranean Transient (EMT). M. atlantica, although being a species typical of cold atlantic waters, is able to survive and reproduce efficiently also at the temperatures characteristic of the north-western Mediterranean and Adriatic, where is now established and one of the main gelatinous carnivorous during spring-summer. The plankton monitoring in the Bay of Tunis indicates only occasional records of M. atlantica. However, recent data in the Bay of Bizerte which is more influenced by the offshore atlantic circulation, show relatively high abundance of M. atlantica in the winter period. Overall M. kochi dominate in the tunisian region, which seems to have environmental characteristics not suitable for M. atlantica to establish. The results of this comparative study indicate that it is fundamental taking into account the different sub-regions dynamics when investigating the effect of climate change in the Mediterranean basin. For this, it is necessary to expand the plankton monitoring, including inshore and offshore waters in the main sub-systems characteristic of the Mediterranean Sea.

Muggiaea atlantica; hydroclimatic changes; Mediterranean

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