INVASIVE SPECIES AND THEIR IMPACT UPON AQUATIC HABITATS
There are countless threats to our aquatic ecosystems that have long lasting impacts upon our Great Lakes Ecosystems. Water pollution/sedimentation, habitat loss/degradation, connectivity, are a few examples and the list goes on and on. One such threat that usually doesn’t get immediate attention until a problem arises is the impact of Invasive Species. These invaders are often responsible for lost species diversity and changing food web dynamics within their new habitats.
If left unchecked, the consequences are often disastrous as ecosystem functionality is either lost or greatly impaired. Invasive Species introductions into our aquatic habitats typically result in dire consequences that can’t be fully understood. Most Invasive Species are undetectable at low population densities and by the time they are discovered problems are already starting to fester. This demonstrates the importance of early detection and the need for forward thinking approaches to minimize future introductions.
In today’s world, people have the ability to travel and visit just about every corner of the globe. Sometimes a foreign hitchhiker can find its way into new habitats often causing unfavorable consequences. Albeit most of these introductions have been unintentional. However, there are some serious repercussions associated with their establishment. These aquatic invaders are usually left unchecked by the lack of natural control mechanisms. Unfortunately, the end result is usually the proliferation of foreign invaders and the ensuing negative impacts upon native flora and fauna.
Predicting the outcomes of an Invasive Species introduction is often difficult. In most cases there are cascading effects that ripple through the ecosystem favoring the introduced organism. The absence of natural population controls on Invasive Species usually results in a competitive advantage for competition and survival. As invasive populations grow, ecosystem sustainability is often lost or greatly impaired leading to reduced Native Species diversity. In the Great Lakes, this could ultimately result in reduced numbers of highly desirable game species.
The Great Lakes region has a growing number of Invasive Species concerns. Some notable examples are the Sea Lamprey, Alewife, Spiny Water Flea, Zebra Mussels, Quaga Mussels, and the New Zealand Mud Snail. All of these examples have consequences that go well beyond the physical parameters of water quality. Often these invaders have substantial impacts upon the trophic structure of our aquatic communities.
The Sea Lamprey almost wiped out the Lake Trout Populations thru uncontrolled predation. Alewife and Spiny Water Fleas had direct and indirect impacts upon Native Zooplankton populations and Juvenile Fish Survival. Zebra and Quaga mussels have changed the trophic cascades in the Great Lakes from the bottom up. This has lead to increasing water clarity, increased light penetration, deep water warming, increased Algal blooms, and reduced Salmonid populations. All of these consequences have direct effects upon the Economical value of our Great Lakes Recreational Sport Fishery.
New Zealand Mud Snail
The newest Invasive Species that is spreading throughout the Great Lakes Region is the New Zealand Mud Snail. The effects of this new invader are not yet fully understood. Researchers believe this invader will have adverse effects upon native snail species diversity by outcompeting native snails for space and food resources. Concerns have also been raised regarding how the New Zealand Mud Snail may effect the primary production elements of stream ecosystems which will more than likely have dire consequences for macro-invertebrate communities and ultimately stream fish populations. In a trout stream this could be detrimental to trout populations as food resources become greatly reduced by their increasing presence.
As we enter a new fishing season I encourage everyone to take extra precautions in sanitizing your fishing equipment. We all need to be more diligent as we move between watersheds to help prevent further spread. For further information regarding the New Zealand Mud Snail and other invasive species, please check out the upcoming webinars from the newly formed Great Lakes New Zealand Mud Snail Collaborative. Join the fight, stop the spread, and get informed.
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