Carbon dioxide emissions could mean trouble for ocean species

The mysterious cold water coral reefs could remain a mystery if the world’s carbon dioxide output stays the same.

The species, which has only been studied for the last 15 years and about which little information known, is highly affected by the depletion of carbonate ions, said Jeff Short, a National Oceanic and Atmospheric Administration research scientist.

“We are jeopardizing (the coral reef) community before we hardly know what’s even there,” Short said.

The whole world could be without coral if emissions levels maintain the same rate, he said.

Carbon dioxide represents only a small fraction of gases found in the atmosphere.

Short said a higher concentration of carbon dioxide is found in sea water. And the percent of carbon dioxide increases in cold water because cooler temperatures have a greater capacity to absorb the gas, which leads to a lack of carbonate ions, a substance needed for creatures that rely on calcium to form shells. Shrimp, crabs, sea urchins and lobsters all need carbonate ions to harden their shells.

Another creature that relies on carbonate ions is a species of shrimp known as the pteropod. Pink and chum salmon depend on pteropods for 40 percent of their diet. Short said the disappearance of the species could have unknown effects on salmon numbers, which could have a big impact on a section of the Alaska salmon industry.

A lack of carbonate ions has the greatest effect on juveniles of shelled species. These species undergo a large energy-expending process to develop their shells. A lack of carbonate ions in the water makes the growing process more difficult.

The acceleration of ion depletion in cold water makes Alaska exceptionally vulnerable to the effects of carbon dioxide acidification. Short named the Gulf of Alaska, the Aleutian Islands and the Southeast region of the state as places where acidification was occurring.

“Alaska is on the forefront of these impacts,” Short said.

Aragonite and calcite are two types of carbonate ions being lost in sea water. The oceans are saturated with both minerals and need to be. If the ions become unsaturated, the shelled creatures can’t use them. The Gulf of Alaska’s depth of saturation is shallow at 50 to 100 meters deep, and a meter of it is disappearing every year.

Short said there are two types of change associated with oceans. The first is a gradual change that can take place throughout 1,000 years. The slow rate of this type of change gives the environment time to adapt.

The second type, “catastrophically quick,” is associated with events such as a meteor hitting Earth or volcanic impact. This kind of quick change results in mass extinction.

Looking at the two choices, Short said the second outcome is more likely to occur in the world’s oceans if carbon dioxide output stays the same.

The outcome of the change is unknown because of a lack of research. Fields that researchers want to explore in regard of such as availability of trace metals and nutrients. But without curbing emissions in the atmosphere and water, the outcome will be more than likely unfavorable.

“There is a great deal of ponderability,” Short said.

Christi Hang,, 24 September 2008. Article.

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