The seas in which corals and other calcifying species dwell are turning acidic, their pH slowly dropping as Earth's oceans acidify in response to increased carbon dioxide...
Coral bleachingLast Updated on 2014-05-12 12:51:51Coral bleaching is the reduction of intracellular endosymbionts in living coral reefs either via loss or expulsion of algal pigmentation. The symbiotic relationship between coral and zooxanthellae is directly related to coral bleaching. When this relationship fails, and the zooxanthellae do not receive required inputs from the coral or vice-versa, the zooxanthellae will pale and turn white or be expelled into the water.
The resultant decline in coral health from bleaching is deleterious to the coral ecosystem. Chief drivers for coral bleaching are freshwater dilution, change in pH, marine water pollution, increase in sunlight or alteration of seawater temperature. Particularly widespread water pollution is in the form of marine sedimentation from excessive runoff and discharge of untreated sewage. In addition to these abiotic causes of coral bleaching, the phenomenon of overfishing... More »
Ocean acidification troublesLast Updated on 2012-08-09 00:00:00
The seas in which corals and other calcifying species dwell are turning acidic, their pH slowly dropping as Earth's oceans acidify in response to increased carbon dioxide in the atmosphere.
Trouble in Paradise:
Ocean Acidification This Way Comes
Sustainability of tropical corals in question, but some species developing survival mechanisms
The following Discovery article is part two in a series on the National Science Foundation's Science, Engineering and Education for Sustainability (SEES) investment. Visit parts one, three, four, five, six and seven in this series.
The following is part five in a series on the National Science Foundation's Long-Term Ecological Research (LTER) Network. Visit parts one, two, three, four, six, seven, eight and nine in this series.
Double, double toil and trouble;
Fire burn, and caldron bubble.
—Shakespeare,... More »
Corals: Storehouse for Temperature DataLast Updated on 2010-11-12 00:00:00
Corals are marine animals that form external skeletons (exoskeletons) of calcium carbonate (CaCO3). Colonies of corals produce reefs in clear, shallow waters. These animals generate denser layers in their exoskeletons during months with severe weather and less dense layers during months with more benign weather. As a result, corals develop discernible annual bands that can be counted to establish the age of a sample.
The ratio of heavy to light oxygen isotopes (represented by ?18O) in shells of marine organisms decreases with the temperature of the surrounding seawater. In shallow waters where corals grow, the ?18O values of the seawater and, thereby, of the corals, also changes with rainfall, evaporation, and river input. Therefore, the ?18O record is often supplemented with other proxy measures of temperature, such as the strontium-to-calcium ratio (Sr/Ca).
Strontium (Sr)... More »
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