By Kelly Derham, Sylvanian Staff Writer
Kelp forests, underwater coastal areas that contain “canopies” of the algae kelp, sustain a large number of species, which make them typically very resilient ecosystems. However, Northern California’s kelp forests have decreased in size by 95% from 2008 to 2019, an alarming trend that may be predictive of what is to come in other kelp forests around the world. Kelp forests provide many ecosystem and commercial benefits. For example, kelp is harvested for pharmaceuticals and fire proofing fabric. Kelp forests may even be able to reduce climate change.
Northern California’s kelp forests are declining due to two stressors. First, there has been unusual and drastic ocean warming in the area. Second, sea star wasting disease is killing the main predator of sea urchins, the sunflower sea star. Since their only predator in the ecosystem is dying, sea urchin numbers are increasing dramatically. Sea urchins feed on kelp, and this has ultimately led to a decrease in kelp forests. Areas which used to have forests of kelp and many other species have turned into beds of sea urchins. Sea otters have historically also been a predator of sea urchins, but due to over hunting in the past, have very low numbers in Northern California.
Kelp is a photosynthesizing primary producer, which means it acquires its energy from the sun, through photosynthesis. During photosynthesis, carbon dioxide is sequestered, or removed from the atmosphere and turned into biomass. A recent study suggests kelp takes in twice as much carbon dioxide as originally thought. And because this carbon is stored away from land, it is less likely to be disturbed than forests on land and returned to the atmosphere. There are even efforts to farm kelp to reduce climate change.
Kelp forests are not only found on the West Coast. A kelp forest also stretches from the northeastern United States to Europe. The main species in these kelp forests is Laminaria (as opposed to Macrocystis nereocystis on the West Coast). This species is also threatened, and researchers predict it may become nonexistent as early as the first half of the 21st century in parts of Europe. Cool-water kelp are stressed by high temperatures, and higher levels of human activity near the shore can change nutrient load, which can threaten these kelp. Sea urchins in the north Atlantic have also deforested major portions of the kelp forest.
Scientists are working on ways to protect these important ecosystems. There have been some efforts for divers to manually remove the urchins in Northern California to see if this is a feasible way to help reduce their numbers. Sea urchins are edible, and it is possible that they could be harvested as sustainable seafood. There have also been general talks about reintroducing sea otters in Northern California and preserving sea stock to repopulate kelp when necessary. Without drastic changes in Northern California kelp forests will have a difficult time recovering, and this could be a sign of what is to come in other kelp forests. Kelp forests around the world have numerous far reaching impacts and need to be protected.
Dodd, Oliver. (n.d.) “Fish Swim through the kelp forest.” Creative Commons. https://search.creativecommons.org/photos/c70a860e-f9d5-4302-84c5-29ae35d86a09
National Marine Sanctuaries. (n.d.) “Kelp Forests: A Description.” National Oceanic and Atmospheric Association. https://sanctuaries.noaa.gov/visit/ecosystems/kelpdesc.html
Fox, Alex. (11 Mar, 2012). “Satellite Imagery Shows Northern California Kelp Forests Have Collapsed.” Smithsonian Magazine. https://www.smithsonianmag.com/smart-news/satellite-imagery-shows-northern-california-kelp-forests-have-collapsed-180977214/
June 26, 2021