Motorboat noise stunts growth and impairs predator escape in reef fish, study shows

New research reveals that motorboat noise has detrimental effects on coral reef fish. Scientists from the University of Exeter, University of Bristol, and James Cook University exposed spiny chromis, a species from the Great Barrier Reef, to either boat noise or natural reef sounds during their embryonic and post-hatching stages. The study, published in Environmental Pollution, found that fish exposed to motorboat noise at both stages grew up shorter and less capable of escaping predators.

Exeter's Dr. Sophie Nedelec explained that motorboat noise can affect parental care behavior, including the oxygenation of eggs during the embryonic phase, which influences their survival. She suggested that early noise exposure might sensitize fish to noise, causing them to respond more strongly to it as juveniles. This could lead to stress, poor feeding, and impaired risk assessment, ultimately resulting in smaller body size.

The fish were divided into four groups and exposed to various noise conditions during different life stages. When tested for predator response in relatively quiet conditions, 80% of fish exposed to natural reef sounds responded by twisting into a "C" shape and fleeing from danger. However, only 68% of fish exposed to motorboat noise as both embryos and juveniles reacted to the predator. Additionally, 40% of those fish swam toward the threat instead of away from it.

Nedelec emphasized that limiting motorboat traffic near reefs during the breeding season could help mitigate these effects and protect reef fish, contributing to the preservation of valuable coral reefs.