Seventy-five percent of coral reefs worldwide are presently at risk from local and global pressures, a figure that could rise to 90 percent by 2030.
Ron Vave/Marine Photobank
A new, comprehensive analysis has found that local and global pressures are threatening 75 percent of the world's coral reefs. The analysis incorporates impacts from climate change, including warming seas and rising ocean acidification but concludes that local pressures—such as overfishing, coastal development, and pollution—pose the most immediate and direct risks.
"Reefs at Risk Revisited," published by the World Resources Institute (WRI) in conjunction with 30 other organizations, including SeaWeb, is an update of a 1998 WRI publication and takes advantage of the latest data and satellite information to map coral reefs to a resolution 64 times higher than the original report. It concludes that more than 60 percent of the world's reefs are under immediate and direct threat from one or more local sources—such as overfishing and destructive fishing, coastal development, watershed-based pollution, or marine-based pollution and damage. That figure rises to 75 percent when local threats are combined with thermal stress caused by rising ocean temperatures, which are linked to the widespread weakening and mortality of corals from mass coral bleaching.
The percent of reefs rated as threatened has increased by 30 percent in the more than 10 years since the first "Reefs at Risk" analysis, with increases being noted in all local threat categories and in all regions. The main cause of greater pressure on reefs since 1998 has been an 80 percent increase in the damage caused by overfishing and destructive fishing, most significantly in the Pacific and Indian Ocean regions, a change that is largely due to the growth in coastal populations living near reefs. Pressure on reefs from coastal development, watershed-based pollution, and marine-based pollution and damage has also increased dramatically from 1998 levels.
Pressures will increase as global threats continue to develop, the report says. The analysis projects that during the 2030s, roughly half of reefs globally will experience sufficient thermal stress to induce severe bleaching in most years. During the 2050s, this percentage is expected to grow to more than 95 percent. At the same time, rising levels of carbon dioxide in seawater are altering the chemistry, and increasing the acidity, of the ocean, reducing the saturation level of aragonite, a compound corals need to build their skeletons. By 2030, fewer than half the world's reefs are projected to be in areas where aragonite levels are ideal for coral growth, suggesting that coral growth rates could be dramatically reduced. By 2050, only about 15 percent of reefs will be in areas where aragonite levels are adequate for coral growth.
The combined impacts of ocean warming and acidification will increase the threat levels on more than half of all reefs by 2030, pushing the percentage of threatened reefs to more than 90 percent by 2030.
Added to the problem, the report finds that just 27 percent of the world's reefs are located within marine protected areas (MPAs), and that this proportion drops to 16 percent for reefs outside Australia. Furthermore, given that quality of management varies from one MPA to another, the reports calculates that only 6 percent of the world's reefs are located in reefs that are managed effectively.
"Well-managed marine protected areas are one of the best tools to safeguard reefs," said Mark Spalding, senior marine scientist at The Nature Conservancy and a lead author of the report. Although local protective measures will not in themselves counter the impacts of global threats arising from climate change and ocean acidification, a growing body of evidence has shown that reducing local threats such as overfishing and nutrient and sediment pollution may allow reefs to recover more quickly from coral bleaching. Strategic planning to enhance local-scale reef resilience should target critical areas, building networks of protected areas that include and replicate different parts of the reef system as well as incorporate areas critical for future reef replenishment.
"Coral reefs are valuable resources for millions of people worldwide. Despite the dire situation for many reefs, there is reason for hope," said Lauretta Burke, senior associate at WRI and a lead author of the report. "Reefs are resilient, and by reducing the local pressures we can buy time as we find global solutions to preserve reefs for future generations."
Source: Burke, L., et al. 2011. Reefs at Risk Revisited. World Resources Institute, Washington, D.C. Available online at http://www.wri.org/publication/reefs-at-risk-revisited.
Contact: Lauretta Burke, World Resources Institute. E-mail: email@example.com.
A new overview has found widespread evidence of climate change affecting Arctic marine ecosystems, although more studies of the impacts on top predators such as polar bears than those on lower trophic forms, such as plankton. Kieran Mulvaney
A new study in the journal Global Change Biology "provides compelling evidence of impacts of climate change on almost all components of the marine ecosystems, from planktonic communities to large mammals." The study, by Paul Wassmann of the University of Tromsø in Norway and colleagues, reviewed published literature to synthesize the footprints of climate change impacts on Arctic marine ecosystems. It found that some changes were better documented than others: For example, numerous papers record the impact of declining sea ice on polar bears but relatively few document examples of changes in planktonic or benthic communities. A relative paucity of records from the Siberian Arctic and the central Arctic Ocean prior to the onset of anthropogenic climate change made quantifying changes in those areas difficult.
However, Wassmann and his co-authors conclude that the available evidence points "to a poleward range shift of subarctic species, impacting the condition and demographics of Arctic species and displacing them from current food webs. There is little doubt that evidence shows only a subset of the changes that have already taken place, and that may have major impact on grossly under-studied ice communities."
Jane Lubchenco, administrator of the National Oceanic and Atmospheric Administration (NOAA), last week announced the development of a NOAA Arctic Vision and Strategy that, among other things, aims to fill in some of the research gaps highlighted in the Global Change Biology paper. The endeavor lists six goals that will pull together many of NOAA's capabilities: forecasting sea ice; strengthening foundational science to understand and detect Arctic climate and ecosystem changes; improving weather and water forecasts and warnings; enhancing international and national partnerships; improving stewardship and management of ocean and coastal resources in the Arctic; and advancing resilient and healthy Arctic communities and economies.
"The Arctic is at once a majestic, harsh and fragile environment. It's the region where we are seeing the most rapid and dramatic changes in the climate. And these regional changes have global implications," said Lubchenco in a speech at the Aspen Institute, which recently released its own analysis of the changing Arctic. "The Shared Future," the report of the Aspen Institute Dialogue and Commission on Arctic Climate Change, identifies strategies and approaches to help conserve the biological resources of the Arctic Ocean and to assure sustainable livelihoods of the communities that depend on these resources for their survival.
"We have no choice: We must protect the Arctic ice, enable it to continue to act as an essential temperature regulator for the planet [and] avoid the catastrophic rise in sea levels that would result from the ice melt," said commission member HSH Prince Albert II of Monaco. "It is a duty for ourselves and for all of humanity—for our children, of course, but also all those who are already suffering the dramatic effects of these developments. Meantime, we must do all we can to help the region respond to warming already in the system."
Sources: Wassmann, P., et al. 2011. Footprints of climate change in the Arctic marine ecosystem. Global Change Biology 17: 1235–1249. doi: 10.1111/j.1365-2486.2010.02311.x
Contact: Paul Wassmann, University of Tromsø, Norway. E-mail: firstname.lastname@example.org
By studying whales fitted with electronic tags, researchers have been able to ascertain that beaked whales alter their behavior in response to naval sonar. Friedlaender, U.S. Navy
Researchers from the Woods Hole Oceanographic Institution (WHOI) have become the first to conclude definitively that naval sonar affects whale behavior and movement. This follows years of anecdotal evidence linking naval exercises with mass strandings of several species of cetaceans.
The research team developed experiments to slowly increase the level of sonar directed at a tagged whale, to stop exposure as soon as the whale started responding, to measure that exposure and to define the response.
"These experiments were very difficult to develop, and it was a major breakthrough simply to be able to develop a study that could safely study these responses," said Peter Tyack of WHOI, the lead author of the study, which was published in the online open-access journal PLoS One. "All three times that tagged beaked whales were exposed experimentally to playback of sounds when they were foraging at depth, they stopped foraging prematurely and made unusually long and slow ascents to the surface, moving away from the sound."
The team then monitored reactions of beaked whales during actual sonar exercises on a naval testing range where an array of underwater microphones, or hydrophones, covered the seafloor, allowing whale sounds to be monitored over 600 square miles (1,554 square kilometers). "During actual sonar exercises, beaked whales were primarily detected near the periphery of the range, on average 10 miles (16 kilometers) away from the sonar transmissions. Once the exercise stopped, beaked whales gradually filled in the center of the range over 2 to 3 days," they write.
In a press release, Tyack said that the research shows beaked whales are particularly sensitive to sound, and that they altered their behavior when exposed to sound levels below those previously believed. But, he added, "The observations on the naval range suggest that while sonar can disrupt the behavior of the whales, appropriate monitoring and management can reduce the risk of stranding."
Source: Tyack, P., et al. 2011. Beaked whales respond to simulated and actual navy sonar. PLoS One 6(2011): e17009; doi:10.1371/journal.pone.0017009.
Contact: Peter Tyack, Woods Hole Oceanographic Institution. E-mail: email@example.com
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