Environmental drivers of coral condition (maximum quantum yield, symbiont density, chlorophyll a
content and coral skeletal growth rates) were assessed in the equatorial inshore coastal waters of
Singapore, where the amplitude of seasonal variation is low, but anthropogenic influence is relatively
high. Water quality variables (sediments, nutrients, trace metals, temperature, light) explained between
52 and 83% of the variation in coral condition, with sediments and light availability as key drivers of
foliose corals (Merulina ampliata, Pachyseris speciosa), and temperature exerting a greater influence on a
branching coral (Pocillopora damicornis). Seasonal reductions in water quality led to high chlorophyll a
concentrations and maximum quantum yields in corals, but low growth rates. These marginal coral
communities are potentially vulnerable to climate change, hence, we propose water quality thresholds
for coral growth with the aim of mitigating both local and global environmental impacts.