Ocean Acidification and Global Warming Disrupt Schools of Fish

Feb, 2022 - By SMI

Researchers at the University of Adelaide, South Australia have recently discovered that ocean acidification and global warming affect the way fish interacts in groups.

The early life stages of marine species including various fish species are vulnerable to predators and an innate ability to detect them can be crucial for survival. They cluster in shoals and show gregarious characteristics to protect themselves against predators as well as acquire food. However, according to Professor Ivan Nagelkerken, the project leader from the University of Adelaide's Environment Institute and Southern Seas Ecology Laboratories, with the current ocean warming, various gregarious tropical fishes are moving poleward and changing their way of interaction with fish in more temperature regions.

The increasing concentration of carbon dioxide in the atmosphere is raising the temperature of the ocean surface, leading to ocean acidification. The researchers studied the new behavior and interaction of fish species under controlled laboratory conditions with changing temperature and acidification. They found that both tropical and temperate fish species are likely to move to the right when coordinating in a shoal, particularly when attacked by a predator. However, under ocean acidification, this behavior was significantly diminished.

The researchers also observed diminished cohesion among the mixed shoals of tropical and temperature species under future climatic conditions created in the laboratory. Additionally, the escape responses of these species from potential threats slowed down. According to Professor David Booth from the University of Technology, Sydney, who collaborated on the study, the findings put a greater emphasis on the direct effects of climate stressors on the behavior of fish species and indirect effects on the way they interact with new species. In the future, the detrimental effect of these stressors on the ability of fish to work together may help in determining the survival of certain species in the ocean.

 The researchers published their findings in the journal Global Change Biology.