Click to watch video of a trawl net scraping the sea floor. An area twice the size of the contiguous United States is trawled each year. savecorals.comWashington DC (SPX) Sep 16, 2010 - Scientists have for the first time estimated the physical footprint of human activities on the deep seafloor of the North East Atlantic. The findings published in the journal PLoS ONE reveal that the area disturbed by bottom trawling commercial fishing fleets exceeds the combined physical footprint of other major human activities considered.

The deep seafloor covers approximately 60% of Earth's surface, but only a tiny fraction of it has been studied to date. Yet as technology advances and resources from relatively shallow marine environments are depleted, human impacts on the deep seafloor are likely to increase.

"Information on the location and spatial extent of human activities affecting the deep-sea environment is crucial for conservation of seafloor ecosystems and for governance and sustainable management of the world's oceans," said Angela Benn of the National Oceanography Centre, who led the new study. …

Using available data for the year 2005, they mapped and estimated the spatial extent of intentional human activities occurring directly on the seafloor as well as structures and artefacts present on the seafloor resulting from past activities.

They looked exclusively at the physical footprint rather than the consequential ecological effects of disturbance, contamination and pollution, which are harder to ascertain. One difficulty that they faced was that of accessing data on human activities that was accurate, up to date and comprehensive, and in a suitable format for analysis. …

Even on the lowest estimates, the spatial extent of bottom trawling is at least ten times that for the other activities assessed, with a physical footprint greater than that of all the others combined.

The study estimated the total area of physical imprint in 2005 to be around 28,000 km2. However many human activities in the deep sea are concentrated in certain areas, particularly in shallower depths between 200 m and 1500 m, and in particular habitats which become disproportionally impacted. …

As demands drive human activities ever deeper the imprint will become more widespread. "Consequently," argues Benn, "there needs to be a much greater understanding of the relative impacts of human activities on the deep seafloor, and in particular how these activities affect seafloor ecosystems and biodiversity."

Human Impacts On The Deep Seafloor

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