TEAM GE-C
BIOLOGICAL IMPACTS OF OCEAN ACIDIFICATION
Ocean acidification has the potential to disturb marine ecosystems through variety of ways. There may also be changes in habitat quality and effects on other ecological processes such as nutrients cycling.
And many of the physiological changes can occur by ocean acidification. Especially, it affects phytoplankton, which serve as the base of marine food webs, and on ecosystem engineers, which create or modify habitat (e.g., corals, oyster, and sea-grasses). Such changes may lead to whole shifts in composition, structure, and function of these systems and affect the services provided to society.
Photosynthetic algae and sea-grasses may benefit from higher concentration of carbon dioxide conditions in the ocean, because they need carbon dioxide to live. On the other hand, studies shown that more acidic environment has a great effect on some calcifying species, including oysters, clams, sea urchins, shallow water corals, deep sea corals, and calcareous plankton. When shelled organisms are at risk, the entire food web may also be at risk.
Some examples of organisms affected by ocean acidification. Red coral (photo courtesy of Jim Barry, MBARI); Sea urchin (photo courtesy of Jim Barry, MBARI); Foramaniferan (photo courtesy of Howard Spero, University of California, Davis); Coral and sea urchins (photo courtesy of Susan Roberts, NRC); Sea grass (photo courtesy of Richard Zimmerman, Old Dominion University); Tropical coral reef and fish (photo courtesy of Susan Roberts, NRC); Coccolithophores (photo courtesy of Mitch Covington, BugWare Inc.); Deep-sea Gorgonian bubblegum coral (photo courtesy of MBARI); and Pteropod (photo courtesy of Russ Hopkroft, University of Alaska, Fairbanks).
First, ocean acidification poses a variety of risks to tropical coral reef ecosystems. Coral reef ecosystems are defined by large, wave-resistant calcium carbonate structures, or reefs. The structures they build provide food and shelter for a wide variety of marine organisms. But, acidification may decrease reef growth by reducing calcification rates, reproduction, and recruitment. Also, it may increase the erosion of existing reef structures.
So acidification decrease in coral reef and shellfish, also, they can’t provide habitats for other marine organisms. Plus, it could also be problems for formation of young marine life or growth of animal plankton. Eventually, whole marine ecosystem will get in trouble due to the acidification.
Second, ocean acidification affects the open ocean. Increase in amount of the carbon dioxide increase calcium carbonate dissolution and reduce calcification. This Reduced rates of calcification will affect the marine calcium carbonate cycle through decrease in calcium carbonate burial in the sediments of the deep sea.
And, ocean acidification also affect the photosynthetic activity processes. Acidification will increase phytoplankton growth, primary production, then this will release more organic matter with shift in carbon to nitrogen to phosphorous(C:N:P) ratios. This change will affect grwoth and reproduction of their consumers (e.g., copepods and daphnids). This small change in composition of the biomass can alter whole ocean carbon storage.
For example, in higher concentration of carbon dioxide, phytoplankton grow well and produce biomass with higher C:N ratio, and it would make the ocean biological pump more efficient in exporting carbon to deep level.
Acidification of the deep ocean will occur more slowly than in surface sea water. But the effect of acidification is much more severe than surface water. Generally, deep-sea organisms live in a cold, dark environment with low nutrient inputs. So they grow slowly and have lower metabolic rates than organisms living in the warmer surface water. And this means that they have low level of capacity for gas exchange. So the organisms in the deep sea are very sensitive to their environment. Therefore, if there is a slightly change of pH or nutrients in deep level of the sea, the organisms in deep sea will die soon or affect marine food chain.