Effects of climate change on Mediterranean marine ecosystems: the case of the Catalan Sea

Calvo, E.; Simo, R.; Coma, R.; Ribes, M.; Pascual, J.; Sabates, A.; Gili, J. M.; Pelejero, C.
Climate Research
The Catalan Sea, between the eastern Iberian coast and the Balearic Islands, is a representative portion of the western Mediterranean basin and makes a valuable case study for climate change effects on Mediterranean ecosystems. Global warming is reflected regionally by a rise in sea level over the last century, an increase in surface temperature of around 1.1ºC in the last 35 years, a progressive salinisation of intermediate and deep waters, and a strengthening of the stratification. A likely scenario of what we can expect in the Mediterranean is characterised by a considerable decrease in rainfall and wind, warmer surface waters and a prolonged stratification period. The effects on Mediterranean ecosystems are evident in: (a) a meridionalisation of the algal, invertebrate and vertebrate species, which favours the more thermophilic species over the temperate species; (b) mass mortality events of sessile invertebrates of the coralligenous communities due to anomalous warm waters during the period that food is scarce; (c) increases in the smallest phytoplankton due to the prolongation of the water stratification period; (d) proliferation of gelatinous carnivores, including jellyfish, due to the temperature rise and the lack of rainfall; (e) a faster acidification of seawater, compared with the global oceans, accompanied by a decrease in the capacity to absorb atmospheric CO2. In order to anticipate and mitigate these predicted changes, we recommend investing in research and observation, conserving areas which serve as indicators of climate change, and reducing other anthropogenic pressures such as habitat destruction, overfishing or pollution which may act, synergistically, to accelerate these changes.
Climate change, Marine ecosystems, Catalan Sea, Mediterranean Sea, Time series
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