The Great Lakes are one of the United States’ greatest treasures, not only for their beauty, but also for the amount of history that is contained within them. Unfortunately, they are enduring several environmental threats that are putting entire ecosystems at great risk, as well as the livelihoods and lives of many people. One of their biggest problems comes from invasive species. As we’ve been able to learn from the lionfish invasion of the tropical Atlantic and the Caribbean, invasive species can quickly overtake native species and destroy an ecosystem that has been in place for decades, sometimes with little chance of regeneration. If you would like to help with the management of these invasive species, there are several programs that can be found through a simple search on the internet.
Unlike the goby that is a popular choice for many aquarium enthusiasts, the gobies that have invaded the Great Lakes are a true menace. These gobies are bottom-dwelling fish, and because of their aggressive nature, are overwhelming native species by taking over their spawning locations and reproducing rapidly. The goby, although diminutive, is a voracious feeder, and is able to forage in complete darkness. Due to their ability to survive in even poor water conditions, the goby has become widespread in the Great Lakes.
There are actually several carp that fall under the name “Asian carp,” but for all practical purposes, there is not one among them that isn’t considered a scourge in the Great Lakes. These carp can have devastating impacts on a number of ecosystems, by way of increasing water turbidity, which causes native fish and bird populations to decline, proving hard to catch based on their filter-feeding habits, and causing physical injury to humans recreating on the water when they jump into the air and strike a person’s body. They have been known to actually break bones!
Originally hailing from the Black and Caspian Seas, the zebra mussel can now be found all across North America in prolific numbers. It is thought the species was introduced by the bilge water of commercial ships containing microscopic larvae. The zebra mussel’s crime is the extent to which they colonize and take over entire native ecosystems, as well as attaching to pretty much anything, causing extensive damage to waterways, harbors, ships, and even water treatment plants. Diving ducks are a natural predator, but the mussels are so widespread they cannot be contained in this way alone.
The ruffe is a more recent addition to the Great Lakes’ invasive species, having made its way here from Eurasia around 1986. Also a prolific spawner, the ruffe is highly competitive for the food and habitat of native species, and its strength is in numbers. They reach sexual maturity in their first year of life, and are capable of laying 45,000 to 90,000 per year. Although they rarely grow larger than 5 inches in length, their fins are lined with sharp spines, making them less than appetizing to predators.
An unsightly appearance makes it easy to dislike the sea lamprey, but the real detractor is their effect on the native species of the Great Lakes. These are parasitic creatures, attaching themselves to their victims with many rows of sharp teeth and relieving them of their life force. Most victims die from blood loss or infection from the open wounds the sea lamprey leaves on their flesh. It is a voracious predator of lake trout, a source of great concern since the lake trout is an apex predator in the Great Lakes. As we all know, apex predators are essential to a healthy ecosystem.The sea lamprey has no natural predators.