Latitudinal and seasonal variation in space use by a large, predatory reef fish, Plectropomus leopardus

1: Temperature directly affects the metabolic rate and resource requirements of ectothermic animals, which is likely to influence their movement and habitat use. Space use is a fundamental component of an animal’s ecology, and the extent of an animal’s home range has consequences for individual distributions, community structure and ecosystem function. As ocean temperatures continue to rise as a result of global warming, determining the effects of temperature on space use and movement patterns of important fisheries species is vital. 

2: Our aim was to investigate the spatial and temporal variation in space use by a tropical fisheries species, the leopard coralgrouper (Plectropomus leopardus), from two latitudinally distinct locations on Australia’s Great Barrier Reef to determine the potential response of large-bodied tropical fishes to ocean warming through behavioural modification. 

3: Using passive acoustic telemetry of 36 tagged individuals, we found that both core use areas (50%KUD) and home range extent (95%KUD) varied with respect to location, season, body size and temperature. Average home range extent (95%KUD) for tagged P. leopardus was 0.32 km² at the high-latitude location (Heron Island) compared to 0.23 km² at the low-latitude location (Opal Reef). However, core use areas (50%KUD) did not differ significantly between the two locations. 

4: Seasonal differences were also apparent at both locations with P. leopardusshowing contraction in home range extent during the summertime. This effect was most pronounced at the low-latitude location where home range was significantly reduced during summer when temperatures exceeded 27°C. 

5: Taken together, our findings indicate that higher ambient temperature may elicit a sustained and significant decline in space use by a commercially important reef fish. Given projected increases in ocean temperature due to global climate change, large-bodied reef fishes may be increasingly constrained in their movement and space use, which will have ramifications for individual fitness, population viability, fisheries productivity and ecological function. A plain language summary is available for this article.