Kelp Deforestation: Can California’s kelp forests be saved before it’s too late?
Written by Wildlife & Welfare Researcher Aimee Du Luart
As part of our July edition of the Environmental Calendar we have been focussing on deforestation. We often think of deforestation on land, but there is another forest in the ocean that also needs urgent protection.
Hidden underwater forests
Kelp Forest - Image: © Reefcause Conservation
Kelp is the world’s largest marine plant, reaching heights of 30-55 metres tall. A root-like system affixes kelp to the rocky seafloor, supporting a tall stalk that extends up through the water column, supporting a gas-filled bulb at the surface. Kelp forests are teeming with life, supporting over 700 marine species at some point during their life stage, providing invertebrates, fish and mammals with food, nursery sites and shelter. They are some of the most dynamic and productive marine habitats in the world. However, unfortunately these complex coastal ecosystems are being wiped out across the globe, replaced by urchin barrens, largely devoid of life.
Forests around the world
Kelp forests provide amazing benefits not only to marine life, but also to humans. Kelp forests are carbon super-stores, rivalling tropical rainforests in terms of the incredible amounts of carbon they’re able to trap, meaning they are important players in the fight against climate change! We also rely on kelp and other algae for over half of our oxygen. Therefore, kelp forests are vital for the health and balance of the entire planet, and it is important that we conserve these critical habitats.
Kelp forests span nearly 25% of the world’s coastlines, with some of the most prolific found in the waters of South Africa, New Zealand and Australia and along the west coast of the Americas. However, all is not well with the world’s kelp forests.
Like most other natural spaces, kelp forests are increasingly threatened by a variety of human impacts. Overfishing, pollution and climate change have taken its toll on kelp worldwide. Some areas are experiencing extreme losses.
Tasmania has lost over 95% of its giant kelp canopy and Norway's coast has lost 80% of its kelp in recent decades.
But few places have been as badly hit as California…
A climate-driven ocean catastrophe
It is estimated that the kelp forests in northern California are worth hundreds of millions of dollars a year in terms of carbon storage, fisheries services, storm protection and tourism. Kelp forests are typically very resilient ecosystems. However, a cascading series of environmental and biological events, exacerbated by climate change, decimated the kelp forests along the West Coast of America.
Sunflower Star on the Olympic Coast of Washington - Image: © Janna Nichols
Since 2013, the West Coast of America has experienced a massive loss of sea stars as a result of the mysterious Sea Star Wasting Disease. This condition causes the sea star’s appendages to curl and look as though they had ‘melted’. The event has been described as one of the largest marine die-offs ever recorded, killing off 90% of the sunflower sea star population. This unique species is now listed as critically endangered.
The dramatic loss of sea star population caused a frightening chain reaction. One of the main prey of the sunflower sea star, the purple sea urchin has a voracious appetite for kelp. Sea otters have historically also been predators of sea urchins, but their population in northern California has drastically decreased due to overhunting. Without sea stars to prey on the urchins, their numbers surged. The urchins created ‘urchin barrens’ – oceanic dead zones where no kelp is able to survive. Urchins found in these barrens can persist for a long time with no food, surviving in a starved ‘zombie-like’ state. In this form, they have little commercial value to divers or nutritional value to other predators.
Urchin barren - Image: © Steve Lonhart, NOAA Monterey Bay National Marine Sanctuary
In late 2014, an unusual marine heatwave which gathered off the coast of Alaska in the previous year, expanded all the way down the west coast to Mexico. This marine heatwave, nicknamed “the blob”, wreaked havoc on ocean ecosystems over the following years. While marine heatwaves can occur naturally, research has linked “the blob” directly to human-induced global warming. Around the same time, a strong El Niño event began to develop, bringing warm water up the coast from the south. Water temperature rose as much as 2.5°C above normal and stayed high for 226 days – the longest marine heatwave ever recorded.
These warm waters are thought to have intensified the spread of the Sea Star Wasting Disease. Kelp forests declined all along the California coast, wiping out more than 90% of the kelp cover along a 200 mile stretch of California’s north coast. By 2015, the kelp forests were mostly gone.
Will the kelp forests bounce back?
Researchers, non-profits, urchin-divers and others are frantically working on methods to protect and rebalance these important ecosystems before it’s too late. Throughout America, a number of projects have been established to help resort kelp forests in various ways, such as planting kelp, removing invasive species, and reintroducing key predators.
Organisations like Mission Blue have been setting out to place protections on kelp forest habitat. In Washington, the University of Washington and Nature Conservancy have collaborated to set up ‘the Sunflower sea star breeding program’, where they aim to reintroduce sea stars to the wild and help restore lost populations. The Bay Foundation ‘Kelp restoration project’ in Palos Verdes, California, utilises local urchin divers to cull empty purple urchins, leaving their shells to biodegrade. Since 2013, they have helped in restoring 57 acres of kelp forest in this region. Similarly, a group of citizen scientists known as Reef Check have been manually removing urchins from selected areas to create small urchin-free zones, allowing kelp to grow. Emerging efforts in Washington and Oregon, such as The Northwest Straits Commission and the Oregon Kelp Alliance, are likewise exploring strategies such as urchin culling, as well as transplantation and sea otter reintroduction. Harvesting sea urchins as sustainable seafood is also being trialled.
Without drastic changes, kelp forests on America’s West Coast will struggle to recover, and this could be a sign of what is to come in other kelp forests around the world. In spite of the daunting scale of the damage to these underwater forests, those involved in the rescue effort remain hopeful. Thankfully, research suggests that ocean temperatures are beginning to cool down along the coast, but we must reduce our carbon emissions to prevent these extreme events from ruining our environment.
Kelp forests play a key role in a thriving ocean system and the health of our planet - something we should all care about. There is still time to protect them, but we need to act now.
Find out more about Mission Blue’s Project Sea Star
Find out more about the University of Washington’s Sunflower sea star breeding program
If you’re interested in supporting the University of Washington’s sunflower sea star captive rearing efforts, visit the “Stars for the Sea” giving page.
