GLOBAL CHANGE AND MARINE ECOSYSTEMS, E. Marañón, M. Lastra, C. Sobrino

Abstract 

Human activities are causing, among other impacts, the warming and the decrease of the pH of surface oceanic waters, as well as an increase in nutrient inputs to the coast zone. These processes of anthropogenic global change have the potential to induce biological responses in marine ecosystems at different organization levels. This chapters aims to describe the effects of ocean warming, acidification and eutrophication on the distribution, abundance and activity of benthic and planktonic populations. Impacts on community biodiversity and ecosystem function are also discussed. Historical data sets, based on in situ and also remote observations, are used to show changes in the composition of the planktonic communities and in the primary production of different oceanic regions. Through the synthesis of experimental analysis, we discuss the effects of warming and acidification on the metabolic activities of populations and communities of plankton, invertebrates and fishes. The effects of warming on intertidal communities are described from a biogeochemical point of view, analyzing the impact on the activity of consumer organisms, the processes of organic matter decomposition and its repercussions on nutrient and CO₂ release. The chapter includes a general vision of future projections on the response of marine ecosystems to global change.