Wild Facts Series: Just when you thought the oceans were dying painlessly!
Carbon Emissions Make Oceans Corrosive!
‘Acidified’ Water Threatens Marine Life on the Continental Shelf from Canada to Mexico: NOAA
Researchers found evidence of corrosive water about 20 miles off the west coast of North America from Canada to Mexico last summer. The ocean water on the western North American continental shelf was previously thought not to be “acidified.”
“Ocean acidification” is caused by the ocean’s absorption of carbon dioxide (CO2) from the atmosphere, a process which makes water corrosive.
Effects of increasing carbon dioxide and temperature on coral reefs. (NOAA Coral Reef Watch)
“Acidification of the Earth’s ocean water could have far-reaching impacts on the health of our near-shore environment, and on the sustainability of ecosystems that support human populations through nourishment and jobs,” said Richard W. Spinrad, NOAA assistant administrator for oceanic and atmospheric research. “This research is vital to understanding the processes within the ocean, as well as the consequences of a carbon-rich atmosphere.”
“Our findings represent the first evidence that a large section of the North American continental shelf is seasonally impacted by ocean acidification,” said Feely. “This means that ocean acidification may be seriously impacting marine life on our continental shelf right now.”
“While this absorption provides a great service to humans by significantly reducing the amount of greenhouse gases in the atmosphere and decreasing the effects of global warming, the change in the ocean chemistry affects marine life, particularly organisms with calcium carbonate shells, such as corals, mussels, mollusks, and small creatures in the early stages of the food chain,” said Feely.
NOAA said: “Previous studies found ocean acidification at deeper depths farther from shore. The researchers said that the movement of the corrosive water appears to happen during the upwhelling season during the spring and summer, when winds bring CO2 -rich water up from depths of about 400-600 feet onto the continental shelf. The water that upwells off of the North American Pacific coast has been away from the surface for about 50 years.
Typical coral-reef community observed in the U.S. Virgin Islands. [Species lables: the image to view labels: Ma, boulder star coral (Montastrea annularis); Dc, knobby brain coral (Diploria clivosa); Pa, mustard hill coral (Porites astreoides); Pp, finger coral (Porites porites); D, dead coral (probably Porites astreoides); O, octocoral (soft coral); S, sponge.] Photograph by Nathan Smiley, USGS.
“The field study collected samples from Queen Charlotte Sound, Canada, to San Gregorio Baja California Sur, Mexico. The closest they found corrosive water was about four miles off of the northern California coast.”
“We did not expect to see this extent of ocean acidification until the middle to the end of the century,” said Sabine. “Because of this effort, we have a baseline for future observations as we continue to study and monitor the relationship of biological and physical processes and their ability to respond to ocean acidification.”
“We did not expect to see this extent of ocean acidification until the middle to the end of the century,” said Sabine. “Because of this effort, we have a baseline for future observations as we continue to study and monitor the relationship of biological and physical processes and their ability to respond to ocean acidification.”
“When the upwelled water was last at the surface, it was exposed to an atmosphere with much less CO2 than today and future upwelled waters will probably be more acidic than today’s because of increasing atmospheric CO2,” said Hales, a professor of chemical oceanography, who is also funded by NASA.
“We don’t know how this will affect species living in the zone below the level of the lowest tides, out to the edge of the continental shelf,” said Ianson, an oceanographer. “We do know that organisms like corals or pteropods are affected by water saturated with CO2. The impacts on other species, such as shellfish and other juvenile fish that have economic significance, are not yet fully understood.”
“In Baja California, we have several Mediterranean-climate coastal lagoons where the main external physical and biogeochemical forcing is from the neighboring coastal ocean, strongly influenced by upwelling,” said Hernandez-Ayon, a coastal oceanographer. “We are concerned about these areas because they play an important role as nurseries and feeding grounds of juvenile fish populations but are also are ideal sites for shellfish aquaculture.” More …
What is Bleaching?
Corals are very sensitive to temperature change: a 1–2º C change in local temperature above their normal summer maximum can lead to a phenomenon called ‘bleaching’, whereby the corals expel their vital algal symbionts (algae which live in the cells of the coral), leaving the coral tissues translucent.
Bleached Coral (Pocillopora) NOAA’s Pacific Islands Fisheries Science Center of the National Marine Fisheries Service.
In 1998, a single bleaching event led to the loss of almost 20% of the world’s living coral. Corals can recover from these events but repeated episodes are likely to weaken the coral ecosystem, making them more susceptible to disease and causing a loss of biodiversity. (Source)
How will ocean acidification affect marine life?
Corals, calcareous phytoplankton, mussels, snails, sea urchins and other marine organisms use calcium (Ca) and carbonate (CO3) in seawater to construct their calcium carbonate (CaCO3) shells or skeletons. As the pH decreases, carbonate becomes less available, which makes it more difficult for organisms to secrete CaCO3 to form their skeletal material. For animals in general, including invertebrates and some fish, CO2 accumulation and lowered pH may result in acidosis, or a build up of carbonic acid in the organism’s body fluids. This can lead to lowered immune response, metabolic depression, behavioral depression affecting physical activity and reproduction, and asphyxiation. Since the oceans have never experienced such a rapid acidification, it is not clear if ecosystems have the ability to adapt to these changes (1,2). Effects of ocean acidification on organisms and ecosystems are still poorly understood. Over the last few years, research has intensified significantly to fill the many knowledge gaps. (Source)
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