Our directory of things of interest

University Directory

Ocean changes leading to kelp overgrazing

  • Written by  Tom Hart
  • Published in Oceans
Kelp Forest Kelp Forest Shutterstock
01 Sep
2014
Changes to the distributions of tropical fish species due to ocean warming is leading to overgrazing of kelp forests and seagrass meadows, a new study has found

Changes to the global climate, as well as ocean warming, are strengthening the currents that transport warm tropical water towards the poles. This leads to the formation of ‘hotspots’, where water temperatures are rising at rates two to three times the global average, allowing tropical fish such as rabbitfish (above) to expand their ranges into temperate areas.

More than 40 per cent of the kelp and algal beds in southern Japan have disappeared since the 1990s due to overgrazing of rabbitfish and parrotfish. Although these fish have been present in the area for some time, their grazing rates have increased as ocean temperatures in winter have risen. Similar effects have been seen in the eastern Mediterranean, the Gulf of Mexico and Australia.

‘In tropical regions, plant-eating fish perform the vital role of keeping reefs free of large seaweeds, allowing corals to flourish,’ said the study’s lead author, Adriana Verges of the University of New South Wales. ‘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.’

Related items

NEVER MISS A STORY - Follow Geographical on Social

Want to stay up to date with breaking Geographical stories? Join the thousands following us on Twitter, Facebook and Instagram and stay informed about the world.

More articles in NATURE...

Wildlife

The winners of the most hotly anticipated photography competition have…

Polar

Artist and geographer Nick Jones was appointed artist in residence…

Oceans

Photojournalist Tommy Trenchard joins a research expedition to the Saya…

Climate

So far, carbon offsets have focused mostly on tree-planting. But…

Oceans

Marine scientists are often too few and too underfunded to…

Wildlife

Indigenous marmosets are under threat from released pets and forest fragmentation

Wildlife

A rare encounter with a leopard in the mountains of…

Oceans

The Saildrone Surveyor, a type of uncrewed autonomous vehicle, has…

Climate

Australia has the highest per-capita use of rooftop solar power…

Wildlife

Ecoacoustics – a way to listen in closely to the…

Wildlife

Ash dieback is set to transform the British landscape. Robert…

Geophoto

Photographer Patrick Wack documents documents changes in the Chinese province 

Climate

A growing tide of legal action is increasing pressure on…

Wildlife

Classifying a group of organisms as a separate species has…

Geophoto

Artist Sarah Gillespie used the historic mezzotint technique for her…

Geophoto

The winners of the 2021 competition of Earth Photo have…

Climate

As climate change dysregulates weather patterns, cases of pest explosions…

Polar

Arctic nations are gearing up to exploit the region’s abundant natural…

Climate

Combining solar farms with biodiversity-boosting plants could result in a…