Featured Research

from universities, journals, and other organizations

Beautiful but a threat: Tropical fish invasion destroys kelp forests

Date:
July 9, 2014
Source:
University of New South Wales
Summary:
The migration of tropical fish as a result of ocean warming poses a serious threat to the temperate areas they invade, because they overgraze on kelp forests and seagrass meadows, a new study concludes. The harmful impact is most evident in southern Japanese waters and the eastern Mediterranean, where there have been dramatic declines in kelps. There is also emerging evidence of damage in Australia and the US from the spread of tropical fish towards the poles.

A school of tropical plant-eating fish including various species that are shifting their distribution towards temperate waters.
Credit: Adriana Verges

The migration of tropical fish as a result of ocean warming poses a serious threat to the temperate areas they invade, because they overgraze on kelp forests and seagrass meadows, a new study concludes.

Related Articles


The harmful impact of tropical fish is most evident in southern Japanese waters and the eastern Mediterranean, where there have been dramatic declines in kelps.

There is also emerging evidence in Australia and the US that the spread of tropical fish towards the poles is causing damage in the areas they enter.

"The tropicalisation of temperate marine areas is a new phenomenon of global significance that has arisen because of climate change," says study lead author, Dr Adriana Verges, of UNSW Australia.

"Increases in the number of plant-eating tropical fish can profoundly alter ecosystems and lead to barren reefs, affecting the biodiversity of these regions, with significant economic and management impacts."

The study is published in the journal Proceedings of the Royal Society B.

As the oceans have warmed and the climate has changed, hotspots are developing in regions where the currents that transport warm tropical waters towards the poles are strengthening.

Increased flow of the East Australian Current, for example, has meant waters south-east of the continent are warming at two to three times the global average. Tropical fish are now common in Sydney Harbour during the summer months.

Japan, the east coast of the US, northern Brazil and south eastern Africa are also strongly influenced by coastal currents that transport warm tropical waters.

"In tropical regions, a wide diversity of plant-eating fish perform the vital role of keeping reefs free of large seaweeds, allowing corals to flourish. But when they intrude into temperate waters they pose a significant threat to these habitats. They can directly overgraze algal forests as well as prevent the recovery of algae that have been damaged for other reasons," says Dr Verges.

Tropical fish expanding their ranges into temperate areas include unicornfish, parrotfish, and rabbitfish.

The study authors include researchers from Australia, the US, Spain, Singapore, the UK and Japan.

Case studies:

Southern Japan:

More than 40 per cent of the kelp and algal beds have disappeared since the 1990s, a phenomenon known in Japan as isoyake. Tropical species including rabbitfish and parrotfish appear to be mainly responsible.

Although these fish have been present for a long time, their annual grazing rates have increased dramatically as ocean temperatures in winter have risen. Corals now dominate the ecosystem in many locations. The changes have led to the collapse of the abalone fishery.

Eastern Mediterranean:

Tropical fish moved into the eastern Mediterranean from the Red Sea after the opening of the Suez Canal. In recent decades, rabbitfish numbers have increased, resulting in hundreds of kilometres of deforested areas and a 40 per cent decrease in the variety of marine species.

As the Mediterranean warms the rabbitfish are expanding their range westward, putting other shallow ecosystems at risk.

US:

There has been a more than 20-fold increase in the number of parrotfish in the Gulf of Mexico -- a species which consumes seagrass at five times the rate of native grazers. The number of plant-eating green turtles and manatees has also increased.

Australia:

In Western Australia, emerging evidence suggests that increases in the number of tropical fish are preventing the recovery of kelp forest damaged by a heat wave in 2011.

In eastern Australia, kelp has disappeared from numerous reefs in the past 5 years and Dr Verges' research suggests intense grazing by tropical fish on the kelp preceded this.


Story Source:

The above story is based on materials provided by University of New South Wales. Note: Materials may be edited for content and length.


Cite This Page:

University of New South Wales. "Beautiful but a threat: Tropical fish invasion destroys kelp forests." ScienceDaily. ScienceDaily, 9 July 2014. <www.sciencedaily.com/releases/2014/07/140709100104.htm>.
University of New South Wales. (2014, July 9). Beautiful but a threat: Tropical fish invasion destroys kelp forests. ScienceDaily. Retrieved October 30, 2014 from www.sciencedaily.com/releases/2014/07/140709100104.htm
University of New South Wales. "Beautiful but a threat: Tropical fish invasion destroys kelp forests." ScienceDaily. www.sciencedaily.com/releases/2014/07/140709100104.htm (accessed October 30, 2014).

Share This



More Earth & Climate News

Thursday, October 30, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Deadly Mudslide in Sri Lanka Buries Houses

Deadly Mudslide in Sri Lanka Buries Houses

AP (Oct. 29, 2014) — A mudslide triggered by monsoon rains buried scores of workers' houses at a tea plantation in central Sri Lanka on Wednesday, killing at least 10 people and leaving more than 250 missing, an official said. (Oct. 29) Video provided by AP
Powered by NewsLook.com
Galapagos Tortoises Bounce Back, But Ecosystem Lags

Galapagos Tortoises Bounce Back, But Ecosystem Lags

Newsy (Oct. 29, 2014) — The Galapagos tortoise has made a stupendous recovery from the brink of extinction to a population of more than 1,000. But it still faces threats. Video provided by Newsy
Powered by NewsLook.com
Saharan Solar Project to Power Europe

Saharan Solar Project to Power Europe

Reuters - Business Video Online (Oct. 29, 2014) — A solar energy project in the Tunisian Sahara aims to generate enough clean energy by 2018 to power two million European homes. Matt Stock reports. Video provided by Reuters
Powered by NewsLook.com
Obama: The US Will Not 'run and Hide' From Ebola

Obama: The US Will Not 'run and Hide' From Ebola

AP (Oct. 29, 2014) — Surrounded by health care workers in the White House East Room, President Barack Obama said the U.S. will likely see additional Ebola cases in the weeks ahead. But he said the nation can't seal itself off in the fight against the disease. (Oct. 29) Video provided by AP
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
 
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:  

Breaking News:

Strange & Offbeat Stories

 

Plants & Animals

Earth & Climate

Fossils & Ruins

In Other News

... from NewsDaily.com

Science News

Health News

    Environment News

    Technology News



    Save/Print:
    Share:  

    Free Subscriptions


    Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

    Get Social & Mobile


    Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

    Have Feedback?


    Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
    Mobile iPhone Android Web
    Follow Facebook Twitter Google+
    Subscribe RSS Feeds Email Newsletters
    Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins