Press

ALBANY, NY --- Using a genetic marker, scientists at the New York State Museum and Germany’s University of Giessen have now conclusively confirmed that the mussels that recently invaded western states, and are threatening to foul their water supplies, are quagga mussels.

For two decades, the quagga mussel and its close cousin, the zebra mussel, have created imbalances in ecosystems in lakes and rivers, and caused billions of dollars in damage in water systems in the eastern U.S., including New York State. But until January, the much feared mollusks have remained out of western waters.

There has been general agreement that mussels found in Lake Mead, Nevada, and other western water bodies since January, were almost certainly quaggas because the shape of the quagga mussel shell is rather distinctive. But in the 21st century, DNA analysis tops the list as the most conclusive proof.

By sequencing the COI gene (mitochondrial gene cytochrome c oxidase subunit I) from Lake Mead specimens, research scientists Dr. Daniel P. Molloy and Dr. Thomas Wilke have now confirmed that the fouling mussels in Lake Mead are a perfect genetic match to Dreissena rostriformis bugensis — the quagga mussel. Molloy, an invasive species biologist with the New York State Museum, did the fieldwork and Wilke, a molecular biologist with the University of Giessen, handled the lab work on this collaborative project. Molloy and Wilke are part of an international team that tracks the movement of invasive species, especially mollusks. Last year they collaborated with Dutch and French scientists to document the movement of quagga mussels across Europe.

“ The COI sequences in Lake Mead are genetically all identical and match 100% those of the quagga mussel,” Wilke said.

“There was little doubt that the Lake Mead mussels were quaggas, but this genetic evidence is the icing on the cake for a conclusive identification,” said John Morse of the University of Texas at Arlington, one of the scientists who initially identified the mussels as quaggas based on their morphology.

“With genetic markers now available to discriminate among species, it was good science to take this additional step,” Molloy added.

The accurate identification of animal pests is always important. This is especially true when they’re invasive Dreissena mussels — finger-nail sized, striped bivalves with a nasty reputation for causing havoc in lakes and rivers. Native to Europe and known only to have invaded eastern North America in the 1980s, they can attach by the thousands to almost any underwater surface, clogging pipes, cutting bathers’ feet, fouling boat hulls, and costing the power industries millions of dollars. Based on their shape alone, the tiny mussels that were discovered in Lake Mead, North America’s biggest reservoir, were identified as quagga mussels — a species of Dreissena. Although there are at least a half dozen species of Dreissena in Europe, thus far only two species are known to have successfully invaded North America — Dreissena polymorpha (zebra mussel) and Dreissena rostriformis bugensis (quagga mussel).

Quaggas, like all zebra mussel species, spread by attaching themselves to the hulls of boats or floating objects, or their larvae can drift downstream. Following their detection in Lake Mead, state and federal authorities have also confirmed the presence of quaggas further down the Colorado River in Arizona and in an aqueduct leading into California. This has generated great concern in southwestern states, and California, Nevada, Utah, and Arizona are now moving quickly to assess the situation and prepare for potential multi-million dollar fouling problems in their waterways. Since there is no known method of eradication, the focus is on preventing the mussels from spreading to other waterways.

“Although quagga mussels were only detected two months ago in Lake Mead, based on the large size of some specimens I’ve seen, they were likely introduced into that lake at least several years ago” said Molloy.

In relation to Lake Mead, the Great Lakes are the closest water bodies harboring large populations of quagga mussels and are thus suspected of being the source from which a mussel-infested boat was transported to Lake Mead. Molloy and Wilke will now collaborate on trying to better identify which location in the Great Lakes region the quaggas came from.

Molloy is an aquatic biologist with the New York State Museum and is the director of its Cambridge Field Research Laboratory in Cambridge. His research over the last 30 years has focused on natural enemies (parasites, predators, and competitors) of freshwater invertebrates, particularly pest species such as zebra mussels and black flies. Understanding the invasion dynamics of zebra mussel species and the impact of biological control on their populations are his current research focus.

Wilke is a professor at the University of Giessen, where he heads the Systematics and Biodiversity Group. His research is centered on the phylogeny, biodiversity, and evolutionary strategies of benthic invertebrates, with special emphasis on ancient lakes.

The New York State Museum in Albany is a cultural program of the New York State Education Department .Founded in 1836, the museum has the longest continuously operating state natural

history research and collection survey in the U.S. Further information can be obtained by calling (518) 474-5877 or visiting the museum website at www.nysm.nysed.gov.