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Oceanographer Looks at Human Impact on the Deep Sea

Posted on | August 5, 2011 | Comments Off

ocean garbage

A variety of marine litter collected in the Mediterranean at more than 1 mile depth. Courtesy of CoML.

The deep ocean contains a diversity of habitats and ecosystems, supports high biodiversity and harbors important biological and mineral resources. Human activities, however, are increasingly affecting deep-sea habitats, resulting in the potential for biodiversity loss and, with this, the loss of many goods and services provided by deep-sea ecosystems. These conclusions come from an international study conducted during the Census of Marine Life project SYNDEEP (Towards a First Global Synthesis of Biodiversity, Biogeography and Ecosystem Function in the Deep Sea).

The authors, more than 20 deep-sea experts including Mānoa Professor of Oceanography Craig Smith, conducted a semi-quantitative analysis of the most important anthropogenic impacts that affect deep-sea habitats at the global scale in the past, present and future scenarios. During the Census of Marine Life program researchers from its five deep-sea projects sampled and studied the different deep-sea habitats around the globe.

The impacts were grouped in three major categories—waste and litter dumping, resource exploitation and climate change. The authors identified which deep-sea habitats are at highest risk in the short and mid-term, as well as what will be the main anthropogenic impacts affecting these areas, in a paper published in Public Library of Science ONE on Aug. 1.

In the past, the main human impact affecting deep-sea ecosystems was the dumping or disposal of litter into the oceans. These activities were banned in 1972, but their consequences are still present today, together with the continuing illegal disposal of litter from ships and the arrival of litter and contaminants from coastal areas and river discharges. In particular, the accumulation of plastics on the deep seafloor that can be ingested by the fauna, has consequences still unknown but predicted to be important. There is also increasing evidence of the accumulation of chemical pollutants of industrial origin, such as mercury, lead and persistent organic pollutants in the sediment and fauna, including in species of commercial interest.

The main problem is that very little is known of the deep sea, making it difficult to evaluate accurately the real impact of industrial activities, litter accumulation and climate change in the deep sea habitats. The deep seafloor covers 73 percent of the oceans. Of this great expanse, only the area equivalent to a few football fields has been sampled biologically. Researchers continue to discover new habitats and species, but the negative impacts of human activity appear to be much faster in reaching the great depths of the oceans.

Read the news release. News release content written by Eva Ramirez-Llodra, Census of Marine Life

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