Noise harming ocean invertebrates and ecosystems - University of Exeter

Noise from human activities is harming ocean invertebrates and ecosystems, new research shows.

Scientists reviewed hundreds of studies on the impact of noise on marine invertebrates (such as crabs, molluscs, squid, prawns and worms).

They concluded that noise caused by humans is harming invertebrates in numerous ways, from cellular level to entire ecosystems.

The international team, including – BarcelonaTech (UPC) and the University of Exeter, call for urgent research to investigate and mitigate these impacts.

“Human activities – especially shipping – are changing the ocean soundscape rapidly, and our study brings together the latest evidence on the impacts of this.” said first author Dr Marta Solé from UPC

The study highlights the multiple impacts of anthropogenic (human) noise on invertebrates:

• It can delay hatching and egg development in crustaceans, and significantly increase abnormalities and death rates among larvae of crustaceans, bivalves (eg mussels and oysters) and gastropods (eg snails).
• Low-frequency sounds can cause injuries and even death. For example, research has shown that sound from underwater explosions can kill blue crabs. After an increase of cephalopods (eg squid and octopus) washing up on beaches in Spain, research showed that noise had damaged their statocysts (hearing organs that help them navigate).
• Impacts on behaviour include many species displaying a “startle” reaction in response to loud sounds. Long-term exposure to noise also affects behaviour. For example, ship sounds limit the ability of shore crabs to change colour to camouflage themselves
• Physiological changes have also been discovered. For example, Mediterranean common cuttlefish showed changes in the protein content due sound exposure – with some of the affected proteins related to stress. In another study, permanent high-level exposure to sound caused a significant reduction in growth rate and reproduction, an increase in aggressiveness and mortality rate, and a reduction in feed intake of shrimp.
• By changing the behaviour and health of predators and prey in complex food webs, noise can affect entire ecosystems – and the researchers say more research is needed to investigate this.

Recent studies have revealed that a wide range of invertebrates are sensitive to sounds, especially via sensory organs whose original function is to allow maintaining equilibrium in the water column and sensing gravity.

The paper, published in the journal Frontiers in Marine Science, is entitled: “Marine invertebrates and noise"