Benthic community and climate change

FIORI, SANDRA M.; CARCEDO, M. CECILIA

MARINE ECOLOGY IN A CHANGING WORLD

Science Publishers/CRC Press/Taylor&Francis

Año: 2013; p. 121 - 139

Benthic marine communities are composed of a diversity of species belonging to different taxa that live in association with the sea bottom. They can be partially or totally buried in the sediment, adhered to the bottom or move without departing too much from the substrate. Depending on their association with substrate type (hard/soft) and depth, these communities settle and develop in a broad range of areas, from the high tide line to the bottom of the deep ocean trench. Benthic species are important for a variety of reasons: - Although the best-known reefs are generated by corals, the skeletal remains of species like molluscs, echinoderms, polychaetes and other invertebrates are also used in reef-building. These biogenic constructions are considered local hotspots of biodiversity: they function as important spawning, nursery, breeding and feeding areas for a multitude of organisms and provide refuge and substrate to an array of organisms including invertebrates and fishes (Kirtley 1968, Nelson and Demetriades 1992, Lindeman and Snyder 1999, Moberg and Folke 1999). - Benthic organisms are also important members of the lower food web, consuming organic matter and phytoplankton. Constituting a source of food for larger organisms such as many fish, shorebird and marine mammal species, they link primary production with higher trophic levels. In addition, a number of benthic invertebrates, particularly clams, are consumed by humans and are used for recreational purposes such as fishing bait - The infauna of nutrient-poor tropical carbonate sediments play a crucial role in bioturbation, oxygenation, nutrient cycling and transport, and processing of pollutants. Many benthic organisms, including filter feeders like clams, scallops and mussels, obtain their food by taking in sea water. As the water flows through their bodies, sediments, organic matter, and pollutants are filtered out and ingested. - The interest in benthic indicators for soft-bottom marine communities has increased dramatically as the need for new tools to assess the status of marine waters has grown. There are a number of advantages to using benthic invertebrate fauna for assessing ecological quality: they are sedentary; they have relatively long life-spans; they comprise diverse species that exhibit different sensitivities or tolerances to stress; and they play an important role in the cycling of nutrients and materials between bed sediments and the overlying water column. Descriptions of benthic variability and its relation to climate change and other global stressors are still evolving as more evidence and time series observations become available. Climate change may modify population dynamics over time and space and change the geographical distribution of communities, sometimes resulting in habitat loss and species extinction, with repercussions for ecosystem functioning and biodiversity.