1 Fluctuations in coral health of four common inshore reef corals in response to seasonal 2 and anthropogenic changes in water quality 3 Nicola K. Browne 1, Jason K.L. Tay 2, Jeffrey Low4, Ole Larson2, Peter A. Todd3 4 1 Department of Environment and Agriculture, Faculty of Science and Engineering, Bentley 5 Campus, Curtin University, Perth, WA 6102 6 2 DHI Water and Environment (S) Pte Ltd, 1 Cleantech Loop, #03-05 CleanTech One, 7 Singapore 637141 8 3 Experimental Marine and Ecology Laboratory, Dept. of Biological Sciences, National 9 University of Singapore, Singapore 117543 10 4 National Biodiversity Centre, National Parks Board, 1 Cluny Road, Singapore 259569 11 Corresponding author 12 Email:
[email protected] 13 Tel: +61 477 427 153 14 15 16 17 18 19 20 1 21 Abstract 22 Environmental drivers of coral condition (maximum quantum yield, symbiont density, 23 chlorophyll a content and coral skeletal growth rates) were assessed in the equatorial inshore 24 coastal waters of Singapore, where the amplitude of seasonal variation is low, but 25 anthropogenic influence is relatively high. Water quality variables (sediments, nutrients, 26 trace metals, temperature, light) explained between 52 to 83% of the variation in coral 27 condition, with sediments and light availability as key drivers of foliose corals (M.ampliata, 28 P.speciosa), and temperature exerting a greater influence on a branching coral 29 (P.damicornis). Seasonal reductions in water quality led to high chlorophyll a concentrations 30 and maximum quantum yields in the corals, but low growth rates. These marginal coral 31 communities are potentially vulnerable to climate change, hence, we propose water quality 32 thresholds for coral growth with the aim of mitigating both local and global environmental 33 impacts.