Coral response in the face of large amplitude internal waves


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Gertraud.Schmidt [ at ] awi.de

Abstract

Much have been said over coral responses to changing water conditions in the face of global climate change, yet there is still a lack of knowledge on the immediate response and adaptations of coral colonies to sudden changes in their surrounding water, a scenario of regular occurrence in the Andaman Sea as Large Amplitude Internal Waves (LAIW) reach coastal reefs bringing with them sub-pycnocline waters with low temperature and low pH, among other characteristics. To explore possible acclimatization of reef corals to those regular and rapid impacts the immediate response in the behavioral and photosynthetic performance (Fv/Fm) levels were investigated, on colonies of Porites lutea naturally exposed to LAIW and on colonies sheltered from their impact, in relation to changes on the water temperature, pH, flow speed and food availability under controlled laboratory conditions. Results show that cold water stress caused polyps to retract further into their calyxes and that effect was even stronger when not only the temperature but also the pH was altered, whereas the pH alone caused further expansion of the polyps, without any apparent deleterious effect over the coral polyp. Nevertheless, the live history of the colonies, meaning whether they were used to the impact of LAIW or not, played a crucial role on the respective responses as those colonies which had never suffered the impact of LAIW waters showed higher retraction levels than the ones used to them revealing clear acclimatization mechanisms. Moreover the effect of food presence in combination to the altered water was also addressed revealing that under LAIW conditions the cues that cause polyps to expand in the presence of food particles are overtaken by the physical mechanisms in respond to the thermal stress. On the other hand low temperature did not seem to influence the photosynthetic yield in the general results however it did shaped the yield results along the duration of the experiments. This study suggests the importance of the role of phenotypic variations in the response of coral colonies to, otherwise, deleterious effects an advantage in the face of global change.



Item Type
Thesis (Master)
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Not peer-reviewed
Publication Status
Published
Eprint ID
32392
Cite as
Pacherres Reaño, C. O. (2011): Coral response in the face of large amplitude internal waves , Master thesis, Bremen University.


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