'Traffic calming' boosts breeding on coral reefs

New research shows that coral reef fish are more successful if motorboat noise is reduced.

Scientists reduced the number of boats within 100m and the speed of those within that distance by introducing traffic calming on three reefs.

They tracked the breeding of fish called spiny chromis and found that most of the time, the offspring were still present at the end of the season.

Each nest contained more offspring at the end of the season and offspring was larger on quieter reefs.

Aquarium tests show that noise can disrupt important parental behaviors, such as fanning eggs with their fins to ensure oxygen supply.

The research was carried out at reefs near the Great Barrier Reef.

With coral reefs worldwide facing multiple threats, the results of our experiment offer a way to help struggling populations.

Reducing boat noise at reefs provides fish with much-needed relief to allow successful reproduction.

Three simple changes that any boat driver can adopt are moving boating channels further away from reefs, driving slowly when approaching reefs, and avoiding anchoring next to reefs.

The solutions put the power in the hands of local people.

No one has tried a field experiment like this before.

We monitored six reefs for a whole summer breeding season, swimming every other day along each reef to monitor the survival of 86 spiny chromis broods in their natural habitat.

Thirty of the 46 nest that were observed on the reefs where traffic calming was implemented had offspring at the end of the breeding season. Only 16 out of 40 still contained offspring on control reefs.

Since spiny chromis hide their eggs in caves in the reef, it's difficult to find them before their offspring emerge, so we ran a parallel study in aquariums to study embryology.

Some spiny chromis parents and eggs were kept with natural reef sounds and others were exposed to intermittent boat noise via speakers in an aquarium study.

Natural sounds fanning continued despite the interruption of boat noise.

The lab study showed that the improvements to breeding are due to limiting noise pollution and not other types of noise from the boats.

The results suggest that reducing boat noise could have major benefits for populations of reef fish, making them more resistant to changes currently being driven by human activity.

Climate change is making it more and more common for hurricanes and other storms to hit.

There are ways to speed up population growth after destructive events.

The team stresses that limiting boat traffic won&t be enough to protect coral reefs.

Professor Steve Simpson from the University of Bristol said that reefs around the world are in trouble.

While we try to tackle the biggest threat of climate change, we need simple solutions that reduce local threats.

Acoustic sanctuaries can help build resilience on coral reefs and give them more chance of recovery.

The paper is in a journal.

More information: Limiting motorboat noise on coral reefs boosts fish reproductive success, Nature Communications (2022). DOI: 10.1038/s41467-022-30332-5 Journal information: Nature Communications Citation: 'Traffic calming' boosts breeding on coral reefs (2022, May 20) retrieved 20 May 2022 from https://phys.org/news/2022-05-traffic-calming-boosts-coral-reefs.html This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only.