Impacts of climate change on coastal benthic ecosystems



Recent climatic trends have resulted in significant responses in marine ecosystems, such as pelagic productivity, shifts in species’ geographical distributions, community composition changes and modifications of migratory patterns (Rosenzweig et al. 2007). The increase in mass mortality outbreaks in coastal ecosystems during the past few decades has also been linked to modifications in environmental conditions caused by climate change (Harvell et al. 1999; Harley et al. 2006). These events have occurred in the context of significant warming of the global average surface (+0.76°C for the 20th century; IPCC 2007) and upper global ocean (+0.3°C from 1950 to 2000; Levitus et al. 2000). Since projections for the 21st century depict an increase in warming (+1.8 or +3.5°C depending on the emission scenario; IPCC 2007), we expect an increasing impact of climate change during the next decades.

The Mediterranean region is considered one of the most affected by the climate change where the increase of average temperature will be also accompanied with a very likely increase in the occurrence of extreme events such as heat waves (Déqué 2007; Diffenbaugh et al. 2007). On the other hand the Mediterranean, with less than 1% of world’s ocean, is considered as a biodiversity hot-spot, harboring around 17000 marine species representing between 4 and 15% of marine species (Coll et al. 2010).

Climate change has been depicted as one of the major threats for the conservation of the rich Mediterranean biodiversity (Coll et al. 2010). In the Mediterranean shifts in species’ geographical distributions and mortality events have been linked to a significant regional warming and to positive anomalies which occurred during the last decades (1999, 2003 and 2006). Under the actual climate projections, the NWM sea surface temperature may experience an average warming of 2 to 4°C by the end of the century (Somot et al. 2008).

Under these conditions, incidences of mortality events may spread over larger geographic areas and a wider spectrum of organisms. This scenario, jointly with other impacts on Mediterranean marine ecosystems, could cause a marine biodiversity loss crisis. Analyzing the impact of these events at appropriate scales (spatial and temporal) and biological organization levels (species, populations, communities) is crucial to accurately anticipate future changes in marine ecosystems and propose adapted management and conservation plans. The project ClimCARES is devoted to develop new approaches to better assess the potential impacts of climate change on coastal areas of the NW Mediterranean region.