Calcification and photosynthesis of Porites lutea in response to large amplitude internal waves (LAIW) in the Andaman Sea


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Gertraud.Schmidt [ at ] awi.de

Abstract

The Similan Islands in the Andaman Sea are impacted by an exceptional oceanographic phenomenon: large amplitude internal waves (LAIW) that travel from West to East. As a result coral reefs on the western side of the Similan Islands are exposed to strong, intermittent variations in environmental conditions. Oceanographic sampling revealed that LAIW are accompanied by temperature drops of up to 4 °C and significant changes in carbonate chemistry resulting in a 30% decrease in aragonite saturation. During LAIW-low season (southeast monsoon), these waves bring offshore deep oceanic water from ~ 125 m depth to reefs on the western side of the Similan Islands and in LAIW-high season (northeast monsoon) from ~ 75 m depth. In this study, the response of calcification and oxygen fluxes in the coral Porites lutea to simulated in situ LAIW conditions was investigated at the Similan Islands. The data indicate a trend that the cumulative negative effects of reduced temperature, light and aragonite saturation may be compensated by metabolic adaptations, maintaining general viability; both calcification and oxygen fluxes were the same for West and East fragments and a higher chlorophyll-a and pigment content were found in West fragments. This may be an indication that P. lutea, a species tolerant of even very low aragonite saturations, can acclimatize and possibly even adapt to natural disturbances such as LAIW. However, a severe bleaching event in 2010, prior to the start of the experiments, may have affected the coral`s metabolism and physiology as a whole and may even have lead to the observed higher oxygen fluxes compared to corresponding values measured for P. lutea before 2010. This increase in oxygen fluxes may have supported calcification and allowed corals to maintain normal calcification rates under LAIW conditions.



Item Type
Thesis (Master)
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Not peer-reviewed
Publication Status
Published
Eprint ID
32390
Cite as
Baum, G. (2011): Calcification and photosynthesis of Porites lutea in response to large amplitude internal waves (LAIW) in the Andaman Sea Master thesis, Bremen University.


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