In the Great Lakes and beyond, invasive species can wreak havoc on aquatic and terrestrial ecosystems. Even the most widespread biological invasions once began from a single moment of introduction into a new region. In several cases, the origin of an invasive species has been the release of exotic house pets into the wild.
A 10-foot long reticulated python was recently found in Metro Detroit after escaping its enclosure, and in this case the animal was luckily returned safely to its owner. While the incident was regarded as a lighthearted news story, it’s important to recognize that the release or escape of non-native pets such as this python can potentially lead to serious ecological impacts.
Pythons’ major ecological toll on the Everglades
The presence of the nonindigenous Burmese python in Florida’s Everglades National Park is one example of the devastating effects that an invasive species can have on an ecosystem. Originally from Asia, this species first came to Florida as pets at least as early as 2000. As a result of their release into the wild, Burmese pythons have now established a breeding population in South Florida and are one of the most concerning invasive species in Everglades National Park, according to the U.S. Geological Survey (USGS). Pythons compete with native wildlife for food and resources and are known to prey on many local species including a variety of mammals, birds, and other reptiles. Severe mammal declines in Everglades National Park have been linked to Burmese python predation. In a 2012 study, populations of raccoons had dropped 99.3 percent, opossums 98.9 percent, and bobcats 87.5 percent since 1997, while marsh rabbits, cottontail rabbits, and foxes effectively disappeared.
Learn more about the Burmese python in the Everglades from the Florida Museum.
Similar issues in the Great Lakes
Unfortunately, the Great Lakes region has also experienced invasive species issues as a result of pets being released into the ecosystem. One example is the common goldfish, a freshwater fish native to Asia that is commonly kept as a pet, but which has become invasive in many areas of the United States, including in the Great Lakes region. Once goldfish are established in areas outside of their native range, they can have severe adverse impacts on the ecosystem. When goldfish forage for food, they can uproot aquatic vegetation which reduces water clarity and releases nutrients that can promote the growth of algae. Removing an established goldfish population is nearly impossible, and the economic costs are significant due to their abundance. As an example, a series of 10 goldfish management events in Minnesota removed over 1.5 million goldfish from a chain of lakes. The best way to protect against the harmful impacts of invasive goldfish is to prevent their introduction in the first place.
One of the most well-known invasive species in the Great Lakes is the zebra mussel, which has severely impacted the lakes’ ecosystems since their introduction in the 1980s. Unfortunately, aquarium moss balls commonly sold in pet stores are contributing to the further spread of zebra mussels across the United States. On March 1st, 2021, staff from the USGS were alerted to the presence of zebra mussels attached to or inside of moss balls sold at pet stores as aquarium plants. So far, zebra mussels found on moss balls have been reported in more than 30 states across the U.S. Zebra mussels damage freshwater ecosystems by filtering nutrients and plankton out of the water and growing or encrusting over native bottom dwelling species and submerged hard surfaces (including out-flow pipes from nearshore cities and industrial buildings, as well as boat hulls and propellers), leading to millions of dollars in damages every year to nearshore infrastructure. Aquarium owners should carefully inspect moss balls prior to placing them in their tanks and should thoroughly decontaminate their tanks if they suspect that they introduced a moss ball containing any accompanying mussel, as a precaution to ensure that zebra mussels are not spread. Doing so will minimize the potential of zebra mussels spreading to the environment where they could contaminate nearby water bodies.
From Burmese pythons in Florida to goldfish and zebra mussel-infested moss balls in the Great Lakes, these stories are examples of how releasing non-native pets can accidentally lead to the spread of invasive species with serious impacts on local ecosystems. To avoid more invasive species introductions like these, pet owners must be careful not to release non-native pets into the environment. This can be done through responsible pet ownership and research before purchase. Potential pet owners must understand that adopting a new pet requires a lot of attention and is a significant commitment.
For more information on responsible pet ownership and reducing invasive species risks, check out these resources:
NOAA Great Lakes Environmental Research Laboratory 