Effects of cyanide on corals in relation to cyanide fishing on reefs

Small fragments of the zooxanthellate corals Pocillopora damicornis and Porites lichen were subjected to a range of cyanide concentrations for various times (i.e. to various cyanide doses). Doses encompassed those likely to be experienced by corals as a result of various cyanide fishing practices. Following the highest doses, corals died; after medium doses, they lost their zooxanthellae (symbiotic algae) resulting in a discolouration or ‘bleaching’; and after the lowest doses they lost zooxanthellae but not in sufficient numbers to cause noticeable discolouration. Respiratory rates of P. damicornis were inhibited by 10–90% following exposure to cyanide but recovered to pre-exposure levels within 1–2 h after transfer to clean sea water.