Earth Science News  





. Ocean Acidification Threatens Cold-Water Coral Ecosystems

Some cold-water coral reefs are home to more than 1,300 species of animals, a diversity rivaling some better known tropical coral reefs.
by Staff Writers
Bellevue WA (SPX) Apr 04, 2006
Corals don't only occur in warm, sun-drenched, tropical seas; some species are found at depths of three miles or more in cold, dark waters throughout the world's oceans. Some cold-water coral reefs are home to more than 1,300 species of animals, a diversity rivaling some better known tropical coral reefs.

Until now, scientists believed bottom trawling - a commercial fishing method in which vessels drag large, heavily weighted nets across the bottom - to be the greatest threat to cold-water corals. Now, however, a new study published in Frontiers in Ecology and the Environment suggests that human activities could be threatening cold water reefs in another way.

Lead researcher John Guinotte, a marine biogeographer at Marine Conservation Biology Institute and colleagues say that increasing amounts of atmospheric carbon dioxide (CO2), driven by the burning of fossil fuels, are dissolving into the oceans, causing them to become slightly more acidic. This change in seawater chemistry could harm deep-sea calcifying animals like corals.

Cold-water corals that make their skeletons from aragonite - a form of calcium carbonate (the main component of limestone) - are most vulnerable. Cold-water, reef-building corals are prevalent in the North Atlantic, where there is a deep layer of water supersaturated with aragonite. In pre-industrial times, more than 95 percent of cold water reefs around the world were found in waters supersaturated with aragonite. However, this layer of supersaturated water is shrinking as concentrations of CO2 increase.

"Scientists have known for years that shallow-water tropical coral reefs are threatened by both warming oceans and chemical changes in seawater caused by the build-up of CO2 in the atmosphere. Above-average seawater temperatures have caused coral bleaching events throughout the world, and the calcification rates of corals exposed to more acidic conditions in laboratory experiments have shown worrisome declines," says Guinotte. "But now we suspect that this increase in CO2 will have a detrimental effect on cold-water corals as well. Cold-water reefs are at greater risk than shallow-water reefs because colder waters are naturally less hospitable for coral growth."

The uptake of CO2 by oceans initiates a series of chemical reactions that increase acidity and decrease carbonate ion concentration in seawater. Corals and other marine organisms (e.g. some species of plankton and mollusks) use carbonate ions to build their skeletons or shells. Model projections indicate that by 2100, only 30 percent of cold-water reefs will still be in waters supersaturated with aragonite. With fewer carbonate ions available, there could be a dramatic reduction in the growth of both the corals and marine plankton species that make their shells from aragonite. As the oceans become more acidic, corals are expected to build weaker skeletons, a process similar to osteoporosis in humans.

Cold-water corals provide habitat for many commercially important fish species and harbor several species of sponges that produce chemicals with anti-cancer and other medicinal uses. Unfortunately, says Guinotte, just as scientists are finding out how diverse and important cold-water corals are, they are being threatened by a one-two punch.

"First, bottom trawlers smash them to bits. Then, ocean acidification will probably slow the skeletal growth and/or lead to weaker skeletons of those that remain. Ocean acidification will likely have serious and wide-reaching impacts, not only for coral ecosystems but for all life in the oceans. Many species of marine plankton use carbonate ions and occupy the base of most marine food webs, so a reduction in their numbers could lead to harmful effects throughout marine ecosystems."

Only a decrease in the burning of fossil fuels is likely to slow this trend, say Guinotte and colleagues.

Related Links
Ecological Society of America
Frontiers in Ecology and the Environment
Marine Conservation Biology Institute

Dust Storms Feed The Worlds Oceans
Woods Hole MA (SPX) Apr 03, 2006
Like most living things, microscopic marine plants need iron and other minerals to live and grow. On land, soil provides a ubiquitous source of minerals, but how do essential nutrients get into vast watery stretches of the open ocean? The question has long mystified oceanographers.

.
Get Our Free Newsletters Via Email
  



  • US Struggling To Find New Disaster Chief
  • Pakistan To Relocate Town Destroyed By Earthquake
  • Engineers Making A Difference Worldwide
  • Tiny Water Purification Packet Helps Save Lives Worldwide

  • UN Decries Biodiversity Decline, Climate Change
  • Better Estimates For Future Extreme Precipitation In Europe
  • Climate Change Deal Will Fail Without US, China And India: Blair
  • Britain Will Exceed Kyoto But Miss Own Targets On Greenhouse Gases

  • Envisat Makes Direct Measurements Of Ocean Surface Velocities
  • NASA Scientist Claims Warmer Ocean Waters Reducing Ice Worldwide
  • Space Tool Aids Fight For Clean Drinking Water
  • FluWrap: Deadly Strain Divides

  • Common Clays Investigated For Use As High Tech Environmental Catalysts
  • New Bioproducts Research Centre Will Help Industry Create Forest Biorefinery
  • New Processing Steps Promise More Economical Ethanol Production
  • The Challenge Of Fueling The Chinese Replicator

  • Supercomputer Explores Avian Flu Vaccine And Isolation Options
  • Rain Worsens Risk Of Disease In Drought-Stricken Ethiopia
  • Simple Idea To Dramatically Improve Dengue Vaccinations
  • Avian Influenza Arrives In Middle East

  • Does Biodiversity Increase As Rainforest Area Expands During Global Warming
  • How Vitamin A And Meiosis Split Life In Two
  • Insect Activities Worth $57Bn In US Alone
  • French Farmers Fear Bears

  • China To Spend Over 1Bn Dollars Cleaning Up Songhua River
  • Evacuations Continue As China Gas Well Leaks After Blast
  • Subsurface Bacteria Release Phosphate To Neutralise Uranium Contamination
  • Universities Collaborate To Reduce Development Impact On James River

  • Why Are Letters The Shape That They Are
  • Technology Terror And Viagra Could Warp Sex And Relationships
  • Cortex Matures Faster In Youth With Highest IQ
  • New Light On Muscle Efficiency

  • The content herein, unless otherwise known to be public domain, are Copyright 1995-2006 - SpaceDaily.AFP and UPI Wire Stories are copyright Agence France-Presse and United Press International. ESA PortalReports are copyright European Space Agency. All NASA sourced material is public domain. Additionalcopyrights may apply in whole or part to other bona fide parties. Advertising does not imply endorsement,agreement or approval of any opinions, statements or information provided by SpaceDaily on any Web page published or hosted by SpaceDaily. Privacy Statement