Invasive Invertebrates

These invaders are trying to ‘mussel’ and claw their way into Lake Champlain. Some have already established themselves, and we can only hope to contain their spread.

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  Quagga Mussels

  Quagga mussels (Dreissena bugensis) are a nonnative nuisance species native to the Caspian Sea area. First introduced to the Great Lakes in 1989, they can now be found throughout the Great Lakes, the St. Lawrence River and in a few inland water bodies in New York. They threaten the Lake Champlain Basin by having the potential to cause many of the same problems that have resulted from zebra mussels.

A close relative to the zebra mussel, scientists believe that it poses a greater threat. Quagga mussels are able to colonize a wider variety of lake bottom surfaces than zebra mussels and have a greater range of tolerance to temperatures, depth and other environmental conditions. In the Great Lakes, quagga mussels are already out-competing and replacing zebra mussel populations, but in greater numbers, resulting in greater negative impacts.

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  The Asian Clam

  The Asian clam (Corbicula fluminea) was first found in the Lake Champlain Basin in August 2010. This bivalve is native to tropical areas in Asia, the eastern Mediterranean, and Australia. Their shells are brown or yellow-green with thick concentric rings on the outside and smooth with a purple tinge on the inside. They are generally smaller than a penny in diameter, but can reach sizes of up to 5cm. Unlike zebra mussels, which hitchhike on boat hulls and colonize on other hard surfaces, the clams prefer open, sandy areas with limited plant growth. They can form thick mats.

The Asian clam is a filter feeder that excretes fecal matter into the water. Research suggests the clams are associated with algal blooms and their presence may change the water chemistry, possibly providing a calcium-rich breeding ground for other potential invasive species such as zebra or quagga mussels. The Asian clam crowds out native species and reduces biodiversity on the lake bottom. Asian clams can clog water intake systems of boats, homes, industry, and municipalities.

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Zebra mussels take over spawning habitats for Lake Trout, Smelt, and other fish. They consume microscopic plants and animals in large quantities, in competition with juvenile fish and native mussels. This also has the effect of increasing water clarity, which has some benefits, but can aid the spread of invasive plants to deeper areas of the lake. Zebra mussels have begun to kill many of Lake Champlain’s native mussels by attaching to their shells, preventing them from opening to feed and respire. Seven mussel species native only to the Basin are now severely threatened.

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  Rusty Crayfish

  The rusty crayfish (Orconectes rusticus)  a species native to Ohio and Tennessee that is  rapidly spreading to many other parts the country including New York and all New England states, except Rhode Island. They have been found in Lake Carmi and were spotted in the lower Winooski River in 2005. Rusty crayfish typically displace or hybridize with native crayfish populations and opportunistically prey on native plants, benthic invertebrates, fish eggs, and small fish. Their aggressive predation of native species decreases diversity, destroys habitat and has an overall negative impact on many aquatic ecosystems. They also may spread Eurasian watermilfoil by fragmenting the plants and defoliating native flora clearing the way for further milfoil infestation.

We’ve looked at the invasive invertebrates that threaten Lake Champlain; what about invasive plants?

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Next:   What About Invasive Plants? ( Next >>)

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