Adelaide (LabNews Media LLC) – Ocean acidification not only directly affects the physiology of reef fish, but also, and perhaps more importantly, destroys their social structures. This is the finding of a new study from the University of Adelaide, published in the Journal of Animal Ecology .
The researchers used natural CO₂ sources off the coast of Japan as a real-world model of future ocean conditions. They found that the decrease in the structural complexity of coral reefs caused by acidification leads to significantly smaller fish schools. Smaller schools, in turn, reduce the collective behavior that is vital for the fish's survival—including more efficient foraging, longer periods spent in open areas, and less time spent hiding.
While the direct effects of higher temperature and lower pH on the behavior of individual fish were minor, the indirect effect through the loss of habitat complexity proved dramatic. The social structures that reef fish rely on for protection from predators and successful feeding behavior collapse under the altered conditions.
“The fish are rarely alone and rely on large schools to distribute risks and better detect predators,” explained study leader Dr. Angus Mitchell. Project leader Prof. Ivan Nagelkerken added that the real threat lies less in direct physiological stressors and more in the destruction of the social and ecological environment.
The results underline that when assessing the consequences of climate change for marine ecosystems, not only individual species but, above all, the complex social and habitat-dependent interactions must be taken into account.
Credits
Gettyd3 plus DNaruse Japan
