Enhanced fast-start performance and anti-predator behaviour in a coral reef fish in response to suspended sediment exposure

Declining water quality, in particular elevated suspended sediments, poses a significant threat to coastal coral reefs. We exposed juvenile anemonefish (Amphiprion melanopus) to two suspended sediment concentrations (0 or 180mgL(-1)) for 7d and examined their predator escape performance and anti-predator behaviour in both clear water and suspended sediments (0 and 180mgL(-1), i.e. acute exposure). After 7-d exposure to suspended sediments, fish responded faster to a mechanical stimulus and exhibited enhanced fast starts compared to individuals reared in clear water, regardless of acute exposure. Fish were also less active and avoided open areas when exposed to elevated suspended sediments in the test arena when compared to clear water, irrespective of prior 7-d exposure. While these changes are likely strategies to compensate for an increased perceived predation risk in suspended sediments, they may also be associated with non-consumptive costs for juveniles living on turbid reefs.