An international study has found chronic bottom trawling removes organic carbon from sea floors and reduces biodiversity by 50 per cent.
The results of the study in Spanish waters suggest that continued deep-sea trawling may lead to environmental effects similar to soil erosion on land
Bottom trawling is carried out deeper in the ocean now than at the beginning of the 19th century, due to declining near-shore fish populations.
To assess the effects of bottom trawling on deep-sea ecosystems, Antonio Pusceddu of Italy’s Polytechnic University of Marche and colleagues collected samples of seafloor sediment in a submarine canyon off the northeastern coast of Spain.
The authors found that sediments from chronically trawled areas contained 52% less organic matter, with 37% slower organic carbon consumption, than sediments from un-trawled areas.
The authors found that organic carbon removed by bottom trawling may constitute between 60% and 100% of the daily organic carbon input to the deep-sea ecosystem.
The results suggest that continued deep-sea trawling represents a global threat to seafloor biodiversity and ecological health, causing environmental effects similar to those originated by soil erosion on land accelerated by humans, according to the authors.
The study, “Chronic and intensive bottom trawling impairs deep-sea biodiversity and ecosystem functioning”, is published in PNAS (Proceedings of the National Academy of Sciences).
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