oa Advanced techniques for characterization of Qatari coral physiology and health under variable environmental conditions

Background: Research at ExxonMobil Research Qatar (EMRQ) includes studies on sensitive ecosystems such as coral reefs, which are a key component of Qatar's marine environment. Understanding the potential impacts from industrial activities and changes in the natural environment, as well as the development of effective monitoring technologies are needed for environmental management of these resources. Using conventional monitoring techniques it can be difficult to identify changes in coral health at early stages, or to obtain objective quantitative data for use in predicting and possibly managing impacts. EMRQ is conducting research to advance a cutting-edge technology - Pulse Amplitude Modulation fluorometry (PAM) that determines health of coral by analyzing the photosynthetic efficiency of algae that live within the coral. EMRQ has shown this technology to be effective for use in the Qatar marine environment through field missions and is currently validating and expanding understanding and application of this technology through unique laboratory studies under controlled conditions. Coral (Acropor sp.) samples collected from mother colonies in Umm Al-Arshan (North of Qatar) are maintained in controlled aquarium conditions. Lab based PAM was used to closely monitor health of corals under baseline conditions and by varying environmental stressors. The study demonstrated for the first time the successful culture of Qatari Acropora in a laboratory setting in Qatar and was used to obtain detailed visual images of photosynthesis processes of the algae associated with the coral under variable conditions. Objective: The specific objectives of the work presented here were to: a) detect biological responses of corals (Acropora and Porites sp.) to different levels of stress stimulants including light, salinity and temperature. b) Monitor coral health including protein and chlorophyll concentrations, zooxanthellae density, and growth rate using microscope imagery and PAM data. c) Compare PAM results from diving cameras to PAM used in laboratory conditions. Methods: Coral (Acropor and Porites) samples were cultured in a pre-acclimatized laboratory aquarium and baseline health was assessed utilizing PAM to indicate photosynthetic conditions. Two aquariums (control and testing) were used to conduct the studies and light conditions, salinity and temperature were varied in the testing aquarium. Other water quality parameters were consistently maintained for both tanks. Coral growth rate and PAM measurements were executed monthly, protein concentration was determined using UV analysis and zooxanthellae were enumerated using a hemocytometer at the beginning and end of the experiment. Results: This study showed that light and temperature conditions are critical factors that have an effect on the Acropora and Porites health. Acropora showed high sensitivity to these conditions, whereas the Porties are found to be more tolerant. Extreme conditions can increase corals susceptibility to disease and eventually bleaching. Conclusion: This study reveals the effect of the varying conditions of light, temperature and salinity on the growth and health of different species of the Qatari corals in a laboratory controlled set-up, different species have different reactions to the same stress conditions. Collected parameters including protein content, zooxanthellae density, growth rate and PAM were used to obtain detailed conclusions about coral health status.