Climate change and coral reef fishes
Department of Environment and Conservation, Perth, Western Australia
Climate change increases the incidence of coral bleaching, storms and disease, which combined with ocean acidification are reducing coral cover globally. Extensive coral loss has had a profound impact on many reef fish, which is initially observed as a decline in highly specialized coral-dependent species. However, if coral skeletons erode and collapse, the loss of structural complexity can affect a much broader component of the fish community. Reduced structural complexity has its greatest impact on small-bodied fish that are closely associated with the reef. The loss of these small-bodied species and juveniles of larger-bodied conspecifics can lead to reduced diversity and replenishment of adult populations. Moreover, as many fish recruit directly to live coral, a decline in both coral and structural complexity will have a devastating impact on future fish stocks.
Increased water temperature and
acidification can also have a direct effect on the physiology, biology and
behavior of coral reef fish, particularly during early life history stages.
Increased temperature is expected to increase growth, development and swimming
of larval reef fish, thereby reducing their pelagic duration time. This may
increase local recruitment and survival of fish but will diminish their
capacity for dispersal. Furthermore, oceanic acidification may inhibit the
ability of larval fish to orientate and detect olfactory cues used to locate
suitable settlement habitat. These direct effects and others, combined with the
indirect effects associated with habitat loss, indicate that climate change
threatens the long-term viability of many reef fish species.