One would not automatically associate rising global temperatures with the personalities of coral reef fishes, but recent research suggests that there is a causal link between the two.
The study by Peter Biro, Christa Beckmann and Judy Stamps demonstrated that normal within-daytime fluctuations in temperature of less than 3°C can have large effects on the personalities of two species of juvenile coral reef fish (the lemon damsel, Pomacentrus moluccensis and the speckled damsel, P. bankanensis).
The authors used newly settled juvenile fish of both species. For the lemon damsel, the authors observed the activity, boldness and aggressiveness of the fish in aquaria over an 11-day period while recording the water temperature.
For the speckled damsel, the authors manipulated the temperature of the water in the aquaria while recording the same observations on the fish.
The authors observed that most of the individuals in their experiments were very responsive to changes in temperature, dramatically increasing their levels of activity, boldness and aggressiveness as a function of increases of only a few degrees of temperature.
In both observational and manipulation studies, the average scores for activity, boldness and aggressiveness increased by 2.5 to 6 times for relatively minor (3°C or less) differences in temperature.
The authors conclude that “...our results suggest the possibility for increasingly disrupted patterns of behaviour in fishes and other ectotherms under a scenario of climate warming, with increases in mean-level activity, boldness and aggressiveness of a magnitude that has been shown to result in greater vulnerability to predation, and decreased survival in other fish populations.”
For more information, see the paper: Biro,PA, C Beckmann and JA Stamps (2010) Small within-day increases in temperature affects boldness and alters personality in coral reef fish. Proceedings of the Royal Society B: Biological Sciences, 277, pp. 71–77.