Marine Biodiversity

Oceans, marine ecosystems and their biodiversity are vital for life on earth. Biodiversity is an all-inclusive term to describe the total variation among living organisms of our planet. In its simplest form, biodiversity or biological diversity is therefore 'Life on Earth' and includes marine biodiversity 'Life in the Oceans. The amazing diversity of life in oceans ranges from microbes to the largest animal ever to have lived on earth – the Blue Whale. The term biodiversity also includes the variations in gens, species and ecosystems. Therefore marine biodiversity also includes the greater diversity of genes in the oceans and the wide range of associated ecosystems including mudflats, mangroves, estuaries and coral reefs.

The three domains of life, bacteria, archaea and eukarya are present in the marine environment. In addition there are viruses. About 250,000 species of marine plants and animals have been scientifically described and a few thousand bacteria and archaea. This known biodiversity only represents a small fraction of the number of existing species in ocean, as investigations on deep sea life, especially the diversity of microbes, is changing the whole concept of biodiversity of oceans.

Life originated in the sea and is much older in the sea than on land. As a consequence, animal and plant diversity at higher taxonomic levels are much greater in the oceans, hosting 33 of the 35 phyla of the planet, of which around 13 are exclusively or mostly marine. We know more about the Moon than about the oceans! Programmes such as programs such as the Census of Marine Life has changed the whole concept of biodiversity of oceans and it has been said that we know only a fraction of the biodiversity that exists in oceans.

An important product of marine biodiversity research should be the necessary knowledge and tools for adequately managing and protecting marine biodiversity. This requires knowledge on genetic and ecological mechanisms that control biodiversity (gene flow, dispersal, adaptive value of genetic polymorphisms, determination of dispersal and recruitment, species interactions including invasions, sediment transport, natural and human-induced catastrophes, etc.). It also requires knowledge on the functional role of biodiversity: what is the variability in genes, species and communities that is required for ecosystem functioning; and models on dispersal of genes and organisms, species interactions and food webs, the interaction between food webs and biogeochemical fluxes, and impact assessment of diffuse and point source pollution, coastal constructions, mass tourism and global climate change.

Support of conservation and sustainable exploitation of biodiversity will require development of rapid assessment techniques for monitoring marine biodiversity (genes, species and biotopes), including the use of molecular techniques, rapid identification techniques such as DNA barcoding, assessment of difficult species (microbes, sibling species, multispecies complexes), pictural taxonomic and identification keys accessible on the World Wide Web and CD-ROM, remote sensing techniques (Satellite Imagery, Side Scan Sonar, multibeam, LIDAR, etc.). It must also provide for the development of data bases and Geographic Information Systems (GIS) for genes, species and habitats. All these things should be part of the marine biodiversity education and research in future.

Source: Carlo H.R. Heip and Jean-Pierre Gattuso (2007). Marine biodiversity. In: Encyclopedia of Earth. Eds. Cutler J. Cleveland (Washington, D.C.: Environmental Information Coalition, National Council for Science and the Environment). [First published in the Encyclopedia of Earth August 6, 2007; Last revised Date February 22, 2012; Retrieved July 28, 2012 http://www.eoearth.org/article/Marine_biodiversity