Invaders on the Menu | Great Lakes Now

Summary

The Great Lakes face an ecological upheaval with over 180 invasive species, notably zebra and quagga mussels, and round gobies. Originating from the Black and Caspian Seas, they arrived via freighters' ballast water. Zebra mussels initially proliferated, causing infrastructure issues. The quagga mussels later replaced them, spreading more widely. Intriguingly, round gobies, another invader, may be controlling mussel populations by preying on their larvae. This interaction has cascading effects on the food chain, with native species adapting to the new presence of gobies in their diet. The mussels' filtering has clarified the water, potentially reverting the lakes to a pre-industrial state, while the future ecological balance remains in flux.

Takeaways

• 🌊 Over 180 invasive species have entered the Great Lakes, causing significant ecological changes.
• 🐚 Zebra mussels and round gobies, introduced more than 30 years ago, continue to impact the lakes' ecosystems.
• 🚢 Invasive species like zebra mussels, quagga mussels, and round gobies arrived via ballast water from ocean-going freighters.
• 🔍 The first zebra mussels were discovered in the St. Clair River around 1988, marking the beginning of their spread.
• 🌡️ Quagga mussels have outcompeted zebra mussels by tolerating colder waters and settling on soft bottoms.
• 🔬 Researchers from the University of Wisconsin, Milwaukee School of Freshwater Sciences, are studying mussel control methods.
• 🤿 A mussel removal project in Good Harbor Bay showed that round gobies may be preventing mussels from recolonizing cleared areas by eating their larvae.
• 🐟 The removal of mussels has led to a decrease in other invertebrates, as they lose their hiding places, making them more vulnerable to fish predation.
• 🐡 The round goby, an invasive species, might be helping to control the quagga mussel population by preying on their larvae.
• 🐍 Native species, including the Lake Erie water snake, are adapting to the presence of gobies, incorporating them into their diets.

Q & A

How many invasive species have entered the Great Lakes?

More than 180 invasive species have entered the Great Lakes.

Which two invasive species arrived in the Great Lakes over 30 years ago?

Zebra mussels and round gobies arrived in the Great Lakes over 30 years ago.

What are the three best-known invasive species in the Great Lakes?

The three best-known invasive species in the Great Lakes are zebra mussels, quagga mussels, and round gobies.

How did these invasive species arrive in the Great Lakes?

These invasive species arrived in the Great Lakes from the Black and Caspian Seas, carried in ballast water by ocean-going freighters.

What was the first year zebra mussels were found in the Great Lakes?

The first zebra mussels were picked up in the St. Clair River around 1988.

What problems did the zebra mussels cause in the Great Lakes?

Zebra mussels caused problems by clogging intakes at water treatment plants and power plants.

How did the quagga mussel differ from the zebra mussels in terms of habitat?

The quagga mussel can live in colder water and on soft bottom, allowing it to spread more widely than the zebra mussels, which are confined to the edges of the lakes because they live on hard substrate.

What was the purpose of the mussel removal project initiated by Harvey Bootsma and his team?

The purpose of the mussel removal project was to see if there was any potential for controlling mussels at least at a small scale in Lake Michigan.

What did the research team discover about the absence of mussels in the cleared area after four years?

The research team discovered that the round gobies might be responsible for the absence of mussels in the cleared area, as they were eating the mussel larvae before they could grow to a significant size.

How did the removal of mussels affect other invertebrates in the ecosystem?

The removal of mussels led to a huge drop in other invertebrates because they no longer had hiding places. This made them more accessible to fish that love to eat them.

How have native fish species adapted to the presence of round gobies?

Native fish species like walleyes, northern pike, and smallmouth bass have started feeding on round gobies. They have adjusted their hunting techniques to catch the gobies, which have a different avoidance behavior than the native species they were used to.

What positive impact has the round goby had on the quagga mussel population?

The round goby, an invasive species, may be helping to control another invasive species, the quagga mussel, by feeding on their larvae.

What changes have been observed in the diets of lake trout due to the presence of round gobies?

Lake trout have been observed shifting their diets from fish like mottled sculpins and alewives to round gobies.

How has the Lake Erie water snake benefited from the round goby invasion?

The Lake Erie water snake, previously endangered, has made a comeback because they love to eat round gobies.

What impact have the mussels had on the water quality of the Great Lakes?

The mussels have filtered the lakes, removing algae and absorbing industrial waste, making the waters clearer.

What is the current state of understanding regarding the long-term effects of invasive species on the Great Lakes ecosystem?

The impact of invasive species on the Great Lakes ecosystem is still unfolding, and the long-term effects are currently unknown. Scientists are trying to understand how the lake works while its dynamics are changing.