Labmanager Logo

'Weedy' Fish Species to Take over Our Future Oceans

“If we look at the total number of fish we actually see that these increase under ocean acidification but local biodiversity is lost,” says researcher

| 2 min read
Share this Article
Register for free to listen to this article
Listen with Speechify
0:00
2:00

Video credit: University of Adelaide

Interested in Environmental News?

Subscribe to our free Environmental Tools & Techniques newsletter.

University of Adelaide researchers have for the first time demonstrated that the ocean acidification expected in the future will reduce fish diversity significantly, with small ‘weedy’ species dominating marine environments. 

Published July 7 in Current Biology, the researchers studied species interactions in natural marine environments at underwater volcanic vents, where concentrations of CO2 match those predicted for oceans at the end of the century. They were compared with adjacent marine environments with current CO2 levels.

“Most research on the impacts of climate change has so far involved the study of individual or small numbers of species over short periods of time,” says project leader professor Ivan Nagelkerken, marine ecologist in the university’s Environment Institute.

“From these studies, there have been predictions that fish biodiversity would be reduced—but we’ve never been able to provide firm evidence before.

“This study was done in a shallow-water temperate kelp ecosystem using volcanic CO2 vents as natural laboratories to get a peek into what future ecosystems might look like. It further shows that forecasting effects of climate change on future ecosystems is impossible if we do not incorporate complex species interactions.”

The researchers showed in surveys and underwater experiments over three years, that in high CO2 marine environments one or two species of the smaller, behaviorally dominant fish proliferate while the less aggressive, and less common species disappear.

“If we look at the total number of fish we actually see that these increase under ocean acidification but local biodiversity is lost,” says professor Nagelkerken. “There are increases in the abundance of food such as small crustaceans and snails and, because the dominant species tend to win almost all combats with other species and are attracted to food much faster, their numbers rise.

“Small weedy species would normally be kept under control by their predators—and by predators we mean the medium-sized predators that are associated with kelp. But ocean acidification is also transforming ecosystems from kelp to low grassy turf, so we are losing the habitat that protects these intermediate predators, and therefore losing these species.

“The result is a lot of what are known as weedy species—somewhat the marine equivalent to rats and cockroaches, plenty of them around but no-one really wants to eat them.”

One way this biodiversity loss could be delayed is by reducing overfishing of intermediate predators.

“We showed how diminishing predator numbers has a cascading effect on local species diversity,” Nagelkerken says. “Strong controls on overfishing could be a key action to stall diversity loss and ecosystem change in a high CO2 world.”

Loading Next Article...
Loading Next Article...

CURRENT ISSUE - November 2024

The Blueprint for Lab Safety Success

Protecting your lab's greatest asset: its people

Lab Manager November 2024 Cover Image
Lab Manager Environmental eNewsletter

Stay Connected with Environmental News

Click below to subscribe to Environmental Tools & Techniques eNewsletter!

Subscribe Today