“Calming motion” promotes reproduction on coral reefs

New research shows that coral reef fish reproduce more successfully if the noise of motor boats is reduced.

Scientists have introduced “traffic calming” on three reefs for the entire breeding season – reducing the number of boats within 100 meters and reducing the speed of those who are at this distance.

They then tracked the breeding of fish called prickly chromium, and found that 65% of nests on quieter reefs at the end of the season still contain offspring, compared to 40% on reefs with brisk motorboats.

The offspring were larger on quieter reefs, and each nest also contained more offspring at the end of the season.

Aquarium tests on the same species show that noise disrupts important parental behavior, including “swinging” eggs with fins to ensure oxygen supply.

The study, led by the Universities of Exeter and Bristol, was conducted on reefs near the Lizard Island Research Station on the Great Barrier Reef in Australia.

«З coral reefs Faced with many threats around the world, the results of our experiment offer a way to help struggling populations, “said lead author Dr. Sophie Nedelec of the University of Exeter.

“Simply reducing the noise of boats on reefs provides fish with the necessary relief for successful breeding.

“Moving boat canals away from reefs, slow movement when approaching reefs and avoiding anchoring near reefs provide three simple changes that can take any boat driver.

“These decisions are handing over power to protect vulnerable ecosystems.”

Dr. Nedzelets added: “No one has tried such a field experiment before.

“We followed six reefs (three with calm movement and three without) throughout the summer breeding season, swimming every other day along each reef monitor the survival of 86 broods of prickly chromis in them natural habitat».

Of the 46 nests observed on the reefs where traffic calming was carried out, 30 still contained offspring at the end of the breeding season. On control reefs (without traffic calming) only 16 of the 40 still contained offspring.

Co-author Dr Laura Velázquez Jiménez of James Cook University said: “Because prickly chromiums hide eggs in caves on the reef, nests are difficult to find before the offspring, so we conducted a parallel study in aquariums to study embryonic development».

In this aquarium study, some parents and prickly chromium eggs were kept playing natural reef sounds, while others were exposed to the intermittent sound of a boat playing through speakers.

The reproduction of the noise of the boat interrupted the trend, but with natural sounds the trend continued unabated.

Co-author Professor Andy Redford of the University of Bristol said: “Additional laboratory research has shown that these improvements in breeding are indeed due to limitation noise pollutionand not other kinds of obstacles from boats ”.

Aggregate results suggest that reducing boat noise can bring great benefits to reef fish populations, making reefs more resilient to the changes currently being caused. human activities.

Cyclones and bleaching are becoming more common due to climate change and are causing destruction when they hit.

Finding ways to accelerate population growth after these devastating events can make the difference between decline or recovery.

However, the team emphasizes that restricting the movement of boats will not be enough to fully protect coral reefs.

Senior author Professor Steve Simpson of the University of Bristol said: “We know that reefs around the world are in trouble.

“While we are trying to fight the biggest threat climate changewe need simple solutions that reduce local threats.

“Acoustic reserves can increase the resilience of coral reefs and help reefs have a better chance of recovery.”

The report is published in the journal The nature of communication.