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These results imply that future changes in ocean temperature, such as those due to climate change, may greatly affect the distribution of life in the sea. The scientists also found a high overlap between areas of high human impact and hotspots of marine diversity.
Much research has been conducted on diversity patterns on land, but our knowledge of the distribution of marine life has been more limited. This has changed through the decade-long efforts of the Census of Marine Life, upon which the current paper builds.
The authors synthesized global diversity patterns for major species groups including corals, fishes, whales, seals, sharks, mangroves, seagrasses, and zooplankton. In the process, the global diversity of all coastal fish species has been mapped for the first time.
The researchers were interested in whether there are consistent "biodiversity hotspots" - areas of especially high numbers of species for many different types of marine organisms simultaneously.
They found that the distribution of marine life showed two fundamental patterns: coastal species such as corals and coastal fishes tended to peak in diversity around Southeast Asia, whereas open-ocean creatures such as tunas and whales showed much broader hotspots across the mid-latitude oceans.
The study also assessed the overlap between hotspots of marine diversity and human impacts, i.e. the combined effects of fishing, habitat alteration, climate change and pollution. Human impacts were found to be particularly concentrated in areas of high diversity, suggesting the potential for severe species losses in these regions.
Co-author Boris Worm of Dalhousie University also highlights the need to maintain biodiversity in the face of these impacts: "biodiversity and the functioning of ecosystems are often tightly coupled, with highly diverse ecosystems providing more goods and services that benefit human beings, as well as being more resilient in the face of disturbance, than less diverse ecosystems. The observed concentration of human impacts in our richest marine areas is a worrying indication of our growing footprint in the oceans."
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