In nature, small changes in the balance of an ecosystem can snowball into big issues. If one link in the chain is damaged, the integrity of the entire system is threatened. This is exemplified in many ways, including when considering the effects of invasive species. The introduction of an unfamiliar animal to an ecosystem can have catastrophic consequences. In a place with complex and beautiful nature like Alaska, it can be particularly damaging. This article will define what invasive species are, discuss 5 that are threatening ecosystems in Alaska, and speculate what can be done to intervene. Here are 5 Invasive species in Alaska.
What is an Invasive Species?
An invasive species is a non-native plant or animal species that is introduced to a foreign ecosystem and causes harm that cripples the environment, economy, or human health. Invasive species can spread intentionally or unintentionally and greatly impact the habitats they invade. They typically spread because they can proliferate unchecked. Not all non-native species have this negative impact and are therefore not all invasive species.
For an example of an invasive species, imagine a hypothetical ecosystem with native grasses, deer, and gray wolves, where each component is an important part of a checks and balances system. The habitat does not become overrun with grass because the deer feed on it. The deer do not overpopulate because both predation by wolves and feeding competition for the grass limit them. The wolves, as apex predators, are not predated upon themselves but are limited by feeding competition for the deer. Every piece of the puzzle keeps the others in balance.
If cheatgrass, a non-native grass species that is highly invasive in the United States, enters this system, it can outcompete the native grass species that the deer rely on. As the cheatgrass grows and native grasses die, the deer populations that rely on those grasses will shrink, and the wolves that rely on the deer will decrease as well. Without intervention, the cheatgrass could supplant the native grasses and the entire system could collapse. Unfortunately, many invasive species have these effects on various fragile ecosystems and this article will discuss 5 of them in Alaska.
1. European Green Crab
The European green crab (Carcinus maenas) is an invasive crustacean species that has had a significant impact on ecosystems along the Pacific coast of North America, including Alaska. They are native to Europe and northern Africa and were first reported in North America in the 1800s and Alaska in 1998. These crabs have not only wreaked havoc on other marine life, but they also cause damage to infrastructure, such as aquaculture facilities or coastal structures.
These crabs are a dangerous invasive species because of their aggressive predation on marine life and their burrowing behaviors. European green crabs are aggressive predators that have been the cause of declining clam, mussel, oyster, other crab, and snail species. By extension, they cause harm to every animal that relies on shellfish populations as a food source. European green crabs affect infrastructure because they burrow into the sediment of a structure causing erosion.
Efforts to control the proliferation of European green crabs in Alaska include monitoring and trapping, as well as community outreach and education. On the Alaska Department of Fish and Game’s website, there is a page where citizens can learn how to get involved. Citizen science projects aim to include the public in large-scale scientific endeavors, like species monitoring. In this case, Alaskans can borrow gear from the government and learn how to monitor European green crab populations.
2. Northern Pike
The Northern Pike (Esox lucius) is an invasive fish species tormenting freshwater ecosystems across Alaska. It was first introduced to the state in the early 1950s intentionally to increase local and tourist fishing. Unfortunately, however, northern pikes are apex predators that the Alaskan native species are not evolved to coexist with. As apex predators, they freely feed on important salmonid species and consequently have a cascading effect down the food chain. Many species rely on salmon and trout, many species rely on the animals that eat salmon and trout, and even more rely on those species. This domino effect is called a trophic cascade. Northern pikes also affect aquatic vegetation and every animal that relies on it. They are omnivorous and feed voraciously on plant and animal life.
In an attempt to control growing northern pike populations, the Alaskan government has implemented regulations regarding their harvest and transport. Removal efforts are also underway; however, northern pikes have a wide distribution and are able to disperse quickly so they are difficult to contain. There is ongoing research that seeks to better understand how the northern pike impacts the ecosystems they are invading, but controlling their spread is still a major problem.
3. Sitka Black-tailed Deer
Another invasive animal species in Alaska we will investigate is the Sitka black-tailed deer (Odocoileus hemionus sitkensis). Although the Sitka black-tailed deer is native to certain parts of Alaska, it has been detrimental to the environment in places where it is not native. These deer are herbivores with an unspecialized, broad diet. They browse upon a large variety of woody shrubs, trees, grasses, and forbs. Consequently, other herbivores who have specialized diets based upon just one of these plants are at risk when competing with the Sitka deer. In addition, the Sitka black-tailed deer over-browses and reduces ground cover that ordinarily prevents erosion. As a result, sedimentation in streams and rivers can negatively affect aquatic species.
Hunting and installing fences are some of the responses to this invasion. The deer’s wide distribution and ability to disperse quickly, however, makes them difficult to eradicate. There is ongoing scientific research attempting to understand the environmental impacts of the Sitka black-tailed deer, but otherwise, fighting back against this versatile invasive species is a major challenge.
4. Elodea
Elodea is a genus of aquatic plant that is native to North America, but not Alaska. It is a common plant in aquariums and has spread around the world unintentionally through aquarium releases, boat trailers, and other human activities. Elodea is a dangerous invader because it is very fast-growing. As it grows, it forms dense mats on the surface of the water that can reduce the sunlight and oxygen available to other aquatic species. Elodea is responsible for the reduction of biodiversity in several ecosystems around the world, including the beautiful water features in Alaska.
Elodea has been particularly impactful to ecosystems on the Kenai Peninsula, Prince William Sound, and the Matanuska-Susitna Valley. Efforts to slow or prevent the spread of Elodea include manual removal, chemical treatments, public outreach, and education. Unfortunately, however, this problem does not yet have a clear solution.
5. Japanese Knotweed
Japanese knotweed (Fallopia japonica) is an invasive plant species that is native to Asia. In the late 1800s, an ornamental plant given as a gift was the source of its introduction to North America. This plant, like Elodea, is extremely invasive because it grows rapidly. Japanese knotweed can grow up to 10 feet tall and spreads quickly through a network of underground rhizomes. It forms dense stands that native plants cannot compete with and has led to the reduction of biodiversity where it invades.
Japanese knotweed is a problematic invasive species because its fast growth is hard to control. It also has serious impacts on human structures by growing through cracks and causing damage to foundations and pipes. Current efforts to slow the spread of Japanese knotweed include manual removal, chemical treatment, and community outreach. Scientific research aims to learn more about the plant to create more effective solutions.
Summary of 5 Invasive Species in Alaska
Invasive Species | Damage Caused | |
---|---|---|
1 | European Green Crab | Their aggressive predation has hurt native species and burrowing causes infrastructure damage |
2 | Northern Pike | These apex predators harm native animal and plant life |
3 | Sitka Black-tailed Deer | Compete with native species for food and cause damage to the environment by wiping out plants – causing erosion |
4 | Elodea | Spreads so quickly and densely that it prevents other plants and animals from getting sunlight |
5 | Japanese Knotweed | Grows so fast and so densely that it degrades biodiversity and causes infrastructure damage |
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