Motorboat noise stunts spiny chromis and breaks their escape reflex
Spiny chromis from the Great Barrier Reef were kept on motorboat noise or natural reef sound for up to 78 days before and after hatching. Fish raised in noise ended up 7 per cent shorter on average; only 68 per cent reacted to a threat, and 40 per cent of those that did swam towards the predator. Sophie Nedelec of the University of Exeter says limiting boat traffic near reefs in the breeding season could reduce the effect.
Science··Evening
Motor noise left fish 7 per cent shorter
According to the Environmental Pollution study by the universities of Exeter, Bristol and James Cook, spiny chromis from the Great Barrier Reef were exposed to engine noise or natural reef sound for up to 78 days before and after hatching. Fish kept in noise after hatching were on average 7 per cent shorter than those raised on reef sound. Phys.org reports that motorboat noise during development limits growth. The University of Exeter stresses that the size gap persisted in fish exposed during both embryonic and juvenile stages. The results come from one species under controlled conditions. Phys.org notes that the work was done under controlled laboratory conditions and in one species.[2], [1]
Escape responses broke; 40 per cent swam toward the predator
24 hours after the sound stopped, a simulated predator attack drew a response from only 68 per cent of fish exposed at both stages, against about 80 per cent for those raised on reef sound. Among those that reacted, 40 per cent in the boat-noise group swam towards the threat, against about 20 per cent in the reef-sound group. Phys.org reports that motorboat noise impairs escape responses with carryover effects that persisted after the sound ended. The University of Exeter highlights that fish exposed at both embryonic and juvenile stages showed the lower response rate. The paper reports both stunted growth and impaired escape responses during development. Phys.org also carries the split in direction: 40 per cent of responders in the boat-noise group swam towards the predator, against about 20 per cent on reef sound.[1], [2]
Breeding-season boat traffic could be limited
Sophie Nedelec of the University of Exeter says limiting boat traffic near reefs in the breeding season could reduce the effect. Phys.org notes that the work was done under controlled conditions and in one species. The University of Exeter carries both the shorter growth and the impaired escape response. Teams from Exeter, Bristol and James Cook published the findings in Environmental Pollution. Phys.org repeats that fish were exposed to engine noise or reef sound for up to 78 days before and after hatching; Nedelec's traffic-limit suggestion speaks to that exposure window.[2], [1]
