Kelp forests function differently in warming ocean

August 23, 2018, British Ecological Society

Kelp forests in the UK and the wider North-East Atlantic will experience a marked change in ecosystem functioning in response to continued ocean warming and the increase of warm-water kelp species, according to a new study led by a team from the Marine Biological Association and the University of Plymouth.

Lead author Albert Pessarrodona, now with the University of Western Australia, said the team studied the ecosystem consequences of an expanding warm-water species, Laminaria ochroleuca, which is proliferating under climate change. The findings are published today in the Journal of Ecology.

"As the ocean warms, species are moving up slopes and towards the poles in order to remain within their preferred environmental conditions. Species with warm affinities are migrating to many habitats previously dominated by cold-water ones, transforming ecosystems as we know them. These so-called novel ecosystems feature a mix of warm- and cold-affinity species, but we don't know whether they can retain desirable ecological processes and functions which human wellbeing relies on", Pessarrodona said.

The scientists studied kelp forests in the southwest of the UK, where the warm water kelp species has increased in abundance in recent years—probably at the expense of a cold-water species, which is less tolerant to warming seas.

"The warm-water kelp Laminaria ochroleuca was actually first detected in the UK in the late 1940s, but is now a common sight along the southwest coast and is predicted to continue expanding northwards in response to climate change, occupying most of the UK and large sections of the wider North-East Atlantic coastline by the end of the century", co-author of the study Dr. Dan Smale, from the Marine Biological Association, said.

Most studies so far have looked at how non-native invasive species introduced by humans alter . Far less attention has been paid to the impacts on ecosystem functioning of species expanding into new habitats as a result of .

Pessarrodona added: "We found that the warm-water kelps essentially acted as a conveyor belt of food production, growing and shedding its leaf-like lamina throughout the year and providing a continuous supply of food. In contrast, the cold-water species only grew during short, discrete periods of the year".

Overall, the warm water species was functionally "faster", with its organic material being rapidly processed by herbivores such as sea snails and limpets and with faster rates of decomposition.

"Our findings suggest that the proliferation of the warm-water kelp will alter the dynamics of North-East Atlantic marine forests by modifying the quantity, quality and availability of food. In other research we have also seen that the warm-water kelp harbors less biodiversity than the cold species. Such changes in the provision of habitat and food could eventually affect commercially important such as crabs, lobsters and coastal fish", Smale said.

However, it is not all bad news. Some of the functions the study examined, such as carbon absorption or food provisioning, were maintained or even enhanced. Moreover, the replacement of cold-water kelps by warm-water ones in the North-East Atlantic means this important habitat will likely survive in the future, in contrast to several other areas of the world, including Japan, Canada and Australia, where kelp forests are disappearing completely.

Explore further: Role of kelp forests in mitigating climate change under threat

More information: Journal of Ecology (2018). DOI: 10.1111/1365-2745.13053

Related Stories

Sea stars critical to kelp forest resilience

August 13, 2018

A study by Simon Fraser University resource and environmental management researcher Jenn Burt reveals that sunflower sea stars play a critical role in the resilience of B.C.'s kelp forests, which are among the most productive ...

The rise of turfs—flattening of global kelp forests

January 18, 2018

Research published today into the state of kelp forests around the world shows they are being degraded into flat seascapes carpeted by short, unwanted turf-algae – and the Western Australian coastline is one of the worst-affected ...

Invasive fish threat to kelp forests

December 15, 2016

Seaweed-eating fish are becoming increasingly voracious as the ocean warms due to climate change and are responsible for the recent destruction of kelp forests off the NSW north coast near Coffs Harbour, research shows.

Recommended for you

Scientists solve mystery shrouding oldest animal fossils

March 25, 2019

Scientists from The Australian National University (ANU) have discovered that 558 million-year-old Dickinsonia fossils do not reveal all of the features of the earliest known animals, which potentially had mouths and guts.

Earth's deep mantle flows dynamically

March 25, 2019

As ancient ocean floors plunge over 1,000 km into the Earth's deep interior, they cause hot rock in the lower mantle to flow much more dynamically than previously thought, finds a new UCL-led study.


Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.