This section discusses four common AIS that are current priorities for many states, 
including one marine species, and examines how climate change may affect these species. 
Although many other species are also high priorities, many of the management activities and 
potential responses to climate change may be transferable from these examples. Each example 
illustrates how climate change can both positively and negatively affect current management and 
control activities. Where the environment becomes less suitable for AIS, their management will 
be positively affected, and in areas experiencing new invasions, management will be negatively 
affected in terms of impact and expense. These species responses illustrate the need for 
monitoring and the sharing of monitoring data in coordinated information systems nationally. 
While the complexities and uncertainties associated with climate-change effects on AIS 
underscore the need for monitoring, coordinating information resources, and engaging in further 
research, state agencies can take some actions now to adapt AIS management to this additional 
challenge using existing information. 
2.5.1. Zebra Mussels 
The zebra mussel (Dreissena polymorpha) population has expanded from its point of 
introduction in the Great Lakes in 1988 to its current range that includes 473 lakes, the five Great 
Lakes, and numerous rivers in 23 states, and most recently, it has been found in aquatic 
ecosystems in Nevada (Benson and Raikow, 2007). Zebra mussels form dense aggregates on 
hard substrates, altering invaded ecosystems by consuming native phytoplankton and other 
species in the water column and significantly reducing biomass. This adversely affects the 
consumed species and also alters food web patterns and changes water properties by increasing 
water clarity and light penetration. Often zebra mussels settle in water supply pipes of industrial 
and agricultural facilities, constricting flow and damaging equipment. Taken together, the zebra 
mussel and the quagga mussel (Dreissena bugensis ) (another Great Lakes invader that causes 
similar impacts and that has a range that is expanding) are estimated to cause $1 billion in 
damages and costs annually (Pimentel, 2003). 
Currently, there have been almost no successful mechanisms to selectively eradicate 
zebra mussels once a population has been established in a water body. 1 Therefore, prevention is 
the key tool to decreasing zebra mussel invasions. Zebra mussels spread by passive transport, in 
ballast and bilge water, and by attachment to boat hulls and other equipment. Important 
'The Virginia Department of Game and Inland Fisheries eradicated zebra mussels from Millbrook Quarry by 
injecting twice the amount of potassium needed to kill zebra mussels over a three week period in the winter of 2006, 
four years after the first report of zebra mussels was submitted to the agency. For more information see: Virginia 
Department of Game and Inland Fisheries. Millbrook Quarry zebra mussel eradication. Available online at 
http://www.dgif.state.va.us/zebramussels/taccessed June 6, 2007]. 
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