Action is required now to bring back California's once-abundant kelp forests. The impacts of predator loss and climate change are combining to devastate living reefs that have defined Alaskan kelp forests for centuries, according to new research published in Science. Science X Daily and the Weekly Email Newsletter are free features that allow you to receive your favorite sci-tech news updates in your email inbox. We provide the first globally comprehensive analysis of kelp forest change over the past 50 Kelp forests, already under attack by armies of urchins, disappeared. The information you enter will appear in your e-mail message and is not retained by Phys.org in any form. The impacts of predator loss and climate change are combining to devastate living reefs that have defined Alaskan kelp forests for centuries, according to new research published in Science. An ecological cascade effect is a series of secondary extinctions that are triggered by the primary extinction of a key species in an ecosystem.Secondary extinctions are likely to occur when the threatened species are: dependent on a few specific food sources, mutualistic (dependent on the key species in some way), or forced to coexist with an invasive species that is introduced to the ecosystem. Some areas are even experiencing a growth in kelp forests, including the west coast of Vancouver Island, where an increasing population of urchin-hunting sea otters has reduced the impacts of the spiny grazers, allowing kelp to flourish. “They form these fronts, and they graze along the bottom and eat everything,” says Mark Carr, a marine biologist at the University of California, Santa Cruz. “Long-term empirical evidence of ocean warming leading to tropicalization of fish communities, increased herbivory, and loss of kelp.” Proceedings of the National Academy of Sciences (2016): 201610725. The impacts of predator loss and climate change are combining to devastate living reefs that have defined Alaskan kelp forests for centuries, according to new research published in Science. Commercial kelp harvesting is potentially the greatest threat to long-term kelp stability. The scientists found that lethal grazing under current conditions was about 35 to 60 percent greater than in preindustrial conditions. Green urchin numbers skyrocketed, and the animals destroyed the kelp forests along hundreds of miles of the archipelago. The upwelling cycles have since resumed. More about Alastair Bland →, Never miss a feature! Predatory fish, like lingcod, may move elsewhere to hunt. “We have sea otters down here, and they’re voracious predators of urchins,” he says. "However, the situation has drastically changed this time around. Biodiversity loss is typically associated with more permanent ecological changes in ecosystems, landscapes, and the global biosphere. When urchin populations spiked in response, the reefs held their ground. The population has collapsed, and the recreational harvest could be banned in the coming year, Catton says. Sea stars — especially Pycnopodia helianthoides, the sunflower sea star — eat urchins. By coincidence, a simultaneous onset of unusual wind and current patterns slowed the upwelling of cold, nutrient-rich bottom water, which typically makes the waters of the west coast of North America so productive. The broader implications of climate‐driven shifts and losses of kelp forest ecosystems are far‐reaching, with likely consequences for the provision of ecosystem services. In western Australia, increases in ocean temperatures, accentuated by an extreme spike in 2011, have killed vast beds of an important native kelp, Ecklonia radiata. November 20, 2017. Kelp forests — luxuriant coastal ecosystems that are home to a wide variety of marine biodiversity — are being wiped out from Tasmania to California, replaced by sea urchin barrens that are nearly devoid of life. Kelp loss and ecosystem shifts in northern California (Rogers-Bennett & Catton 2019). The progression of the destruction of a kelp forest in Tasmania by urchins, from left to right. Background: The world’s oceans are warming and it’s no big secret. Lobsters — which prey on urchins — had been heavily fished here for decades, and consequently few predators existed to control the invading urchins, whose numbers boomed. So far they’ve managed to clear 52 acres … While the most effective way of doing this is by reducing carbon emissions, experts increasingly think that this will not be enough. Once an ecosystem has undergone an abrupt change, recovery to the original state is slow, costly, and sometimes even impossible. 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