There are two phenotypes of D. bugensis that have been reported in the Great Lakes: the \"epilimnetic\" form, which has a high flat shell, and the \"profunda\" form, which has an elongate modioliform shell and has invaded soft sediments in the hypolimnion. The epilimnetic form uses its byssal threads to attach to objects and particles and form druses or colonies. The profunda morph can form colonies and attach to objects with its byssal threads or it can partially bury itself in soft sediments and extend its very long incurrent siphon above itself to bring in suspended food particles (Vanderploeg et al. 2002).

Reduction in Native Biodiversity:\r\nD. bugensis causes changes in the structural characteristics of zooplankton including total abundance, biomass and species composition. Specifically, there is an inverse relationship between zooplankton abundance/biomass and density of Dreissena mussels (Grigorovich & Shevtsova, 1995). Dreissena infestations have caused upwards of 95% reduction in unionid numbers and extirpated eight species of unionids in some areas of the Great Lakes (Schloesser et al. 1998; Schloesser & Masteller 1999). Individuals attach themselves to the shells of other mussels, forming encrusting mats many shells thick (10-30mm). \r\n

Modification of Natural Benthic Communities: Dreissena negatively affects benthic invertebrate communities, especially filter-feeding or deep-dwelling invertebrates that rely on detrital rain (Dermott and Munawar 1993, Strayer et al. 1998, Johannsson et al. 2000, in Haynes et al. 2005). Predicting benthic invertebrate community response to a change in nutrient levels is very difficult, and the potential synergistic effects of nutrient alterations and exotics such as Dreissena are complex (Haynes et al. 2005).\r\n

Economic: Thick encrustations of mussels form on man-made structures or within raw water systems, impacting on operation and efficiency. D. bugensis can have major detrimental impacts on recreational and commercial shipping/boating as well as on water-using industries, potable water treatment plants and electric power stations (Ussery & McMahon, 1995).

Prevention: Studies suggest that humans are responsible for most introductions of zebra and quagga mussels into new areas. The best way to prevent and manage dreissenid invasions in open waters is thought to be prevention through public outreach and education. Examples of this include public signage and wash stations at boat launches and other potential introduction points (Frischer et al. 2005).\r\n\r\n

Detection: One of the most important criterions for successful eradication of a species is early detection allowing control measures to take place while the incursion is still relatively small. Detection relies on monitoring and education. In Lake George, NY zebra mussels were detected in 1999 while the population was relatively small. Control efforts between 1999 and 2007, mainly using physical means and SCUBA, were successful in eradicating zebra mussels from the lake (Wimbush et al. 2009).\r\n\r\n

Chemical Control:\r\nChemical control is one of the most common methods for control or eradication. Chlorination is often used; D. bugensis is more sensitive to chlorination than D. polymorpha. Thus chlorination programs currently in use to combat D. polymorpha are more than sufficient to simultaneously control D. bugensis. Another alternative has been potassium permanganate, especially for drinking water sources, even though chemical controls are not environmentally sound solutions. D. polymorpha was recently eradicated from Millbrook Quarry, Virginia using 174,000 gallons of potassium chloride solution over a 3 week period in 2006 (Virginia Department of Game and Inland Fisheries, 2005). Other chemical control options include chlorine dioxide, sodium hypochloride, ozone, mollusicides and polymers (D’Itri, 1996).\r\n\r\n

Physical:\r\nDecreasing water levels of water bodies to cause desiccation of D. bugensis is an effective, readily applied and environmentally neutral technique. It would be most effective in raw water systems such as navigation locks and water intake structures, which are designed to be periodically dewatered for maintenance. This is a particularly attractive method of control because it could be utilized to mitigate fouling not just by D. bugensis but also mixed populations of this species and D. polymorpha (Brady et al., 1996; Ussery & McMahon, 1995). Other physical methods include manual scraping, high-pressure jetting, antifouling coatings and mechanical filtration.\r\n\r\n\r\n

Biological Control: Research is currently underway to test the effectiveness of the CL145A strain of the bacteria Pseudomonas fluorescens which produces a toxin that destroys the digestive system of Dreissena spp. (Molloy & Mayer 2007).\r\n\r\n

Other: A variety of other control methods in use or being developed are oxygen \r\ndeprivation, thermal treatment, radiation, molluscicides, ozone, antifouling coatings, electric currents, and sonic vibration (D’Itri, 1996; Mackie & Claudi, 2009). Fears and Mackie (1995) investigated the use of low-voltage currents for preventing settlement and attachment by D. bugensis by using steel rods and plates with the current running through them placed near the intake of a pulp and paper plant. Complete prevention of settlement was achieved at 8 volts/in with steel rods on both wood and concrete surfaces (Fears & Mackie, 1995).