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The aquatic kelp forests are among the most productive ecosystems on the planet. These giant seaweed pillars, which are commonly found along the Pacific coast of North America, provide food and shelter to thousands of marine species.
Co-author of the study, Bob Miller is a biologist with the Marine Science Institute (MSI) of the University of California at Santa Barbara.
"The complex physical structure of giant kelp that spans the entire water column and its very high productivity are unique," Miller said. "No other species in the kelp forest can replace the large capacity of giant kelp to physically alter the environment and produce habitat and food for a myriad of other species."
For this reason, giant kelp is known as a "fundamental species", an organism playing a major role in the structure of a community.
Giant kelp is generally able to withstand strong ocean currents and can even recover from storms at an impressive rate of about three percent of its weight per day. However, according to research biologist MSI Dan Reed, the violent disturbances expected from climate change could devastate the kelp forests around the world.
"One of the expectations of climate change is that many types of disturbances – for example, fires, hurricanes and floods – will occur more often or will become more and more serious," Reed said. "Ecologists have long recognized the important role disturbances play in the structuring of natural communities. However, they have not yet determined how natural communities would react to increasing the frequency of disturbances in relation to increasing their severity. "
Max Castorani is a professor of environmental science at the University of Virginia and principal investigator of the study.
"We found that the frequency of disturbance was the most important factor affecting the biodiversity of kelp forests, while the severity of disturbances in a given year played a minor role," said Professor Castorani. .
Over the last nine years, researchers have indexed and measured every three months more than 200 species of fish, plants and invertebrates in large experimental kelp forests off the coast of Santa Barbara.
By simulating annual disturbances where kelp forests were experimentally reduced each year, the team discovered that the number of smaller plants and invertebrates attached to the seabed, such as algae, corals and the sponges, had doubled. At the same time, the number of shellfish, such as clams, starfish, lobsters and crabs, has been reduced by 30-61%.
"Our results surprised us because we expected that a single severe winter storm would result in big changes to the biodiversity of kelp forests," Castorani said. "Instead, the number of disturbances over time had the greatest impact, as frequent disturbances prevent the recovery of giant kelp, with significant consequences for the surrounding marine life."
An ecosystem supported by an unhealthy kelp forest is less protected and generally less complex and productive.
David Garrison is director of the National Research Council's Long-Term Ecological Research Program (LTER), which funded the study.
"It is telling that the severity and frequency of disturbances are affecting kelp beds communities in different ways," Garrison said. "We need this kind of research to predict what the future kelp bed communities will look like and what ecosystem services they will provide."
The study is published in the journal Ecology.
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By Chrissy Sexton, editor of Earth.com
Paid by Earth.com
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