Boaters can prevent spread of invasive species


by Jennifer Fjelsted

June is invasive species month in Wisconsin. Invasive species can have big impacts on water quality, so it is important to understand which species Green Lake already has and take steps to prevent any new ones from entering.

One particularly annoying aquatic invasive species in Big Green are zebra mussels, which likely were introduced by human activity. When boaters travel from lake to lake, they can unknowingly transport aquatic invasive species.

At birth, zebra mussels are microscopic and can easily hitch a ride in the water inside live wells, bait buckets, and even boat motors. This is why it is vitally important that lake-goers drain all of the water before and after entering a lake.

Zebra mussels cause a variety of problems. Their shells can clutter and stink up shores. They are incredibly sharp and will cut feet if someone is unlucky enough to step on them. They also can damage property, like water intake pipes, docks and boat motors — in addition to the damage they do to water quality.

Since zebra mussels are filter feeders, it may initially appear that they are cleaning the water.

However, these mussels are actually disrupting the lake’s food chain: clearing the water and allowing sunlight to penetrate deeper into the lake, which promotes excessive growth of plants and algae.

Eurasian water-milfoil (EWM) is an invasive plant species in Green Lake. When EWM plant fragments break off, those small, individual pieces have the ability to float away, sprout roots and grow a whole new plant. Additionally, this is a way that EWM spreads to other lakes. Small fragments can be stuck to boats or trailers, and if not closely inspected and removed, a 1-inch piece of plant can establish a new population in another lake.

These two examples are not the only aquatic invasive species present in the lake’s water. Big Green has other invasive plants and animals such as curly leaf pondweed, purple loosestrife, rusty crayfish and the well-known carp.

Even though Big Green already has these aquatic invasive species that will require continued monitoring and management, there are invasive species in nearby lakes — like spiny waterflea and starry stonewort — that Green Lake does not yet have and need to be prevented. 

Once an invasive species is introduced into a lake, it becomes very difficult to manage and is likely impossible to remove completely. The best way to protect lake health from the harmful impacts of invasive species is through preventing them from getting into the lake in the first place.

At boat launches, there are invasive species prevention signs reminding all lake visitors to take protecting the water seriously. Draining all water, never transporting plants, mud or animals into or away from a lake, and closely inspecting all equipment before entering a body of water are vital steps that prevent the spread of invasive species.

Additionally, Green Lake boat launches will have new tool boards installed that list the aquatic invasive species prevention steps and are equipped with tools to help grab plants off of boats and trailers that are in hard-to-reach places.

Big Green is an incredible lake that adds so much value and joy to the community. It is important to give back to the lake through careful actions that prevent new invasive species from damaging water quality.

June may be invasive species month, but protecting water quality is a year-round job. Be sure to look for the new signs and tools, and join all lake-goers in helping to keep Big Green clean!

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