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The Gap Year Blog

The Importance Of Keystone Species

23 Nov 2017 12:45 PM

Keystone species are integral to their specific ecosystem and habitat, as they play a role deemed vital to the existence of the species which share their home. They define an entire ecosystem. Without its keystone species, ecosystems would be dramatically different or cease to exist altogether. Here we explore the importance of Keystone Species.

Although every species plays an important role in maintaining an ecosystem, some species have a disproportionately larger effect on their environment; these species are called “keystone species”, and they have a critical role in maintaining the structure of a specific habitat, even though they may be small in numbers. Their existence is often viewed as crucial for their ecosystem, and they can affect many other organisms in the same ecosystem, helping determine the types and numbers of various other species in the community.

Flickr | Rosemary In Time

The term keystone species was first coined by Robert Paine (1966) after his extensive studies examining food webs in intertidal ecosystems in the Pacific Northwest. It was discovered that the purple sea star, also known as the Pisaster Orchraceus, prevented mussels from overpopulating rocky intertidal ecosystems. In Paine’s experiment, in which he removed the Pisaster from the intertidal ecosystem, he noticed dramatic changes to the area. Within three months of the Pisaster’s removal, one species of barnacle had occupied 60% to 80% of the available space, and within nine months, a different species of barnacle had replaced it. Eventually, the succession of species wipes out populations of benthic algae, and as a result, some species, such as the limpet, emigrated from the ecosystem due to a lack of food. This discovery was merely the beginning of learning about the importance of Keystone Species.

Other Keystone Species

There is a variety of different categories of Keystone Species, and they all play a different role in theirecosystem. There are Keystone Predators, such as the grey wolf and the sea otter; if predators are removed from the ecosystem, populations of their prey exponentially increase. When there are predators, there is prey, and species of Keystone Prey include salmon and kelp. Other categories of Keystone Species include Keystone Modifiers and Keystone Mutualists; the modifiers modify their habitats such as beavers and prairie dogs, and keep habitats maintained for themselves and other species. Mutualists participate in mutually beneficial interactions, with the most notable example being hummingbirds. Otherwise known as link species, hummingbirds pollinate highly specialized plants adapted to pollination only by these birds.

Flickr | Tom Shockey

Elephants: The Mega-Gardeners of the Forest

It has been noted that without the help of the elephant, a single species of acacia tree tends to dominate the forests of Africa. Whilst usually, the thriving of a plant species would be deemed a good thing, the problem with the fluctuation of acacia trees is that they block sunlight for many other plants they share their space with, and balance is key in nature. This is where elephants come in – being the big, arguably clumsy animals they are, the gentle giants knock down acacia in their search for food, opening up space for other plants to flourish. Furthermore, the wholes that are created on acacia trees from the branches falling being knocked create perfect small hiding places for lizards; reportedly much more common in areas where elephants roam!

Flickr | Diana Robinson

If there’s one thing elephants love to do, that is eat, and a lot. The good thing about this, is that all their eating results in a lot of dung…why is that a good thing, I hear you ask? Elephants produce about a metric ton of dung every week, and this dung becomes a mini ecosystem in itself, as it is rich in nutrients that the elephants can’t process themselves. Fungi live in it, as do insects like beetle larvae, crickets and spiders. In 2009 three species of frog were found happily living in Asian elephant dung! And of course, it is an excellent fertilizer – plants have been shown to thrive better in elephant dung that waste from any other species.

Grey Wolves: An Example of Keystone Species Removal

Grey wolves were once in America. During the latter part of the nineteenth century, most of the important prey for wolves — bison, deer, elk, and moose — were severely depleted by human settlers. When the Greater Yellowstone Ecosystem was declared a national park in 1872, about three to four hundred wolves were present. Fearing the wolves' impact on elk and bison herds as well as livestock owned by area ranchers, the federal government began destroying the wolf population. By the 1930s wolves had been effectively eliminated from the contiguous 48 States and Mexico and only remained in high numbers in Alaska.

Flickr | Don Burkett

With their primary predator no longer a threat, elk populations exploded, leading to the overgrazing of plants. Significant declines in the populations of many plant species resulted, which in turn influenced other wildlife, such as beavers as the Elk were feeding on the supplies which they rely on. The wolves were deemed endangered in 1966, and the subsequence Endangered Species Act of 1973 called for their restoration. In 1995, wolves returned to Yellowstone Park to help manage the rising elk population, but their effect went far beyond that; the return of the wolves helped save this nature haven, and resulted in countless species flourishing.

Major roles in Conservation

Flickr | Ludovic

Some conservation strategies have now shifted focus to the Keystone Species. As ecological systems are the more prone to disturbances, the effects may sometimes further accelerate a series of events, affecting the stability of the system as a whole. In some cases extinction of a single species can lead to the loss of many other species in the ecosystem! Keystone Species can be targeted for conservation approaches to maintain diversity, and used to retain the community structure intact. Coral, for example, is not only prone to extinction itself, but also can be inhabited by species prone to extinction. This Keystone Species is integral to the existence of coral cities, and we are only now learning the catastrophic effect of the decline of a particular Keystone Species.

Keystone Species play a central role in nature cycles, helping keep order in their ecosystems. They are proof that everything must have a balance, and conservation efforts are more needed than ever not only to protect single species, but entire ecosystems and habitats.

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By Fran Collis - Online Journalism Intern