Experimental Evaluation of the Response of Coastal Mediterranean Planktonic and Benthic Metabolism to Warming

The Mediterranean Sea has been identified as one of the hotspots for climate change. Intense warming in the Mediterranean Sea may have strong implications for biological activity and ecosystem functioning. To elucidate the effects of warming on planktonic and benthic metabolism, we performed experiments under different increasing temperature regimes, ranging from three to six different temperatures. The lowest range of temperatures assessed was of 2.6 A degrees C and the maximum was 7.5 A degrees C. Our results suggest that a 6 A degrees C warming of the Mediterranean waters may yield a mean increment in planktonic respiration rates of coastal communities of 24 %, higher than the mean increase expected for planktonic gross primary production (9 %). These results confirm earlier theories, and agree with previous experiments, of a higher increase in respiration rates than in primary production with warming, with the subsequent consequences for the carbon cycle, resulting in a negative feedback to climate warming, as ocean communities will capture less CO2.