Zebra mussel

Clams, mussels, and other bivalves are a serious problem in many cooling water systems. Zebra mussels and freshwater Asiatic clams are relative newcomers to the United States. Because of a lack of natural predators and prodigious reproduction rates, they have rapidly become a serious threat to the operation of many cooling water systems. 

The Great Lakes have suffered the invasion of numerous exotic species of which the smelt, alewife and sea lamprey are probably the best known. More recently, two more species have entered the lakes probably via ballast water from foreign ships. The ruffe (Gymnocephalus cemuus) a small percid, feeds on the eggs and larvae of other percids and whitefish. The ruffe is currently considered to be a threat to Lake Superior s 5- 10 million whitefish fishery. The zebra mussel (Dreissena polymorpha) was discovered in Lake St. Clair in 1985 (31). It has subsequently been discovered at locations throughout the Great Lakes and is of major concern not only environmentally but economically. It has already colonized numerous industrial and domestic water intakes in sufficient numbers to entirely block water flow and is also an intermediate host to parasites which eventually invade fish. 

Another application for the future will be "C02 for Zebra Mussel Control". A project developed by Iberdrola and the University of Salamanca shows that carbonic acidification just in the... 

The water temperature and thermal behaviour of the reservoirs of Mequinensa and Riba-roja have been dealt with in different studies and reports. These include water quality controls commissioned by the Ebro River Authority, the CHE [36-39], some study by the Catalan Water Authority, the ACA [42], several degree and PhD thesis at the Technical School of Civil Engineering of Barcelona [43—48] and research projects aimed to study the dispersion of the zebra mussel Dreissena polymorpha [40, 41]. However, the reservoir with the most information available regarding its thermal behaviour is the reservoir of Riba-roja as it has received an important research effort because of the invasion of zebra mussel. 

The summer pattern of circulation with the Segre River flowing above the Ebro River water has been pointed as providing optimal epilimnetic conditions for the growth of the zebra mussel [40]. 

CH Ebro (2005) Economic evaluation of the zebra mussel invasion in the Ebro basin (Perez L, Chica C). Internal document, pp 48. http //oph.chebro.es/DOCUMENTACION/Calidad/ mejillon/en inicio.htm... 

Faria M, Huertas D, SotoDX, Grimalt JO, Catalan J, Riva MC, Barata C (2010) Contaminant accumulation and multi-biomarker responses in field collected zebra mussels (Dreissena polymorpha) and crayfish (Procambarus clarkii), to evaluate toxicological effects of industrial hazardous dumps in the Ebro river (NE Spain). Chemosphere 78(3) 232-240... 

First, a brief explanation of the current knowledge regarding the sources and cycling of Hg and its transformation into MeHg is presented. Later, in this chapter, THg and limited data on organomercury levels in aquatic organisms of the Ebro River basin are detailed. The aquatic organisms most commonly studied in the Ebro River basin are zebra mussel, red swamp crayfish, and different fish species, namely European catfish, northern pike, common carp, rudd, roach, barbell, and bleak. 

Keywords Aquatic organisms, Chlor-alkali plants, Crayfish, Fish, Mercury, Methylmercury, Zebra mussel... 

MeHg Concentrations and MeHg/THg Ratios in Zebra Mussel and Fish. 252... 

Total Mercury in Aquatic Organisms of the Ebro River Basin 2.1 Zebra Mussel... 

Zebra mussel (Dreissena polymorpha) is a freshwater bivalve belonging to the Dreissenidae family. The common name, zebra, refers to the zebra stripes pattern on the shell and the scientific name, polymorpha, is derived from the many morphs or forms which occur in the shell color pattern, including albino and solid black or... 

Zebra mussel is native to Eastern Europe however, it has spread all over the continent during the last 200 years [37]. In the mid 1980s, the species reached North America, where it colonized the Great Lakes and extended by the Mississippi River to the Gulf of Mexico [38], In the Flix area, local residents found some zebra mussel in 2001. The occurrence of these species in the Ebro River is accidental. In fact, the larvae probably arrived brought in the water where living baits are transported. Other pathways could have been boats or anchors [39],... 

In addition to its broad occurrence under contrasting conditions, easy collection, relatively long life span, and resistance to the accumulation of toxic chemicals, zebra mussels provide a link between the pelagic and benthic food webs, possibly creating a rapid pathway for contaminant transfer from sediments to predators such as common carp (Cyprinus carpio) and, occasionally, humans [32, 42—4-7]. Consequently, zebra mussel has been considered a potential sentinel organism for assessing Hg redistribution from point sources in the Ebro River and the degree of bioavailability to river and wetland food webs. 

In fact, an extensive work on mercury and organomercury levels in zebra mussels collected in several sampling sites in the Flix reservoir area has been reported [32]. The specific sampling points were located in (a) hot spot, (b) wildlife reserve located on the river bank opposite the factory, (c) the meander located immediately downstream from the dam, and (d) a reference site located 1-2 km upstream from the reservoir (Fig. 2). 

The average THg concentration of all tissue samples (n = 285) was 0.2482 0.2546 pg/g, wet weight, ww, ranging from 0.0148 to 0.8052 pg/g. The highest levels were found at the factory site, close to the waste dumping point, followed by the meander, wildlife reserve, and reference sites (Table 1). This fact indicates an important mercury uptake by zebra mussels at the hot spot and redistribution to areas located immediately downstream and near to the river bank opposite the dumping site. 

The range of THg concentrations found in zebra mussels from the Flix dam area (0.16-6.81 pg/g, dry weight, dw) was the highest ever reported worldwide (Table 2). 

Fig. 2 Location of the lower Ebro River catchment, zebra mussel, crayfish, and fish species sampling sites in the Flix dam area. Samples were taken at several stations in the four areas (RF = control site upstream WR = wildlife reserve HS = hot spot or chlor-alkali plant, and MD = meander). Positions of dams (black bars) and overflow dams (grey bars) are indicated to illustrate the mutual isolation of aquatic organisms sampled...

Table 1 Mean and range THg concentrations (pg/g ww) in zebra mussels at the different stations investigated in the Flix area. Adapted from [32]...

Table 2 Comparison of mean concentrations of THg (pg/gdw) in zebra mussels and crayfish from...

As zebra mussel, red swamp crayfish can be used to monitor the aquatic environment for Hg pollution owing to its capacity to accumulate metals in its tissues [54]. Other features, namely abundant populations, long life cycle, widespread distribution, and relatively sedentary lifestyle, also contribute to use this crayfish as bio-indicator of monitoring environmental quality [55]. 

In the Flix area, the determination of THg levels in muscle of red swamp crayfish individuals sampled has been reported [48]. Several specimens were collected in the same stations as zebra mussels. 

Unlike THg, a limited data set about the occurrence of organomercury compounds in biota of the Ebro River has been noticed. MeHg concentrations were only determined in zebra mussel specimens in the Flix hot spot [32] as well as some fish species living in Flix dam (Diez, unpublished results). 

Carrasco L, Diez S, Soto DX, Catalan J, Bayona JM (2008) Assessment of mercury and methylmercury pollution with zebra mussel (Dreissena polymorpha) in the Ebro River (NE Spain) impacted by industrial hazardous dumps. Sci Total Environ 407 178-184... 

Mackie GL (1991) Biology of the exotic zebra mussel, Dreissena-polymorpha, in relation to native bivalves and its potential impact in Lake St-Clair. Hydrobiologia 219 251-268... 

Minchin D, Lucy F, Sullivan M (2002) Zebra mussel impacts and spread. In Leppakoski E, Gollasch S, Olenin S (eds) Invasive aquatic species of Europe distribution, impacts and management. Kluwer Academic Publishers, Dordreicht, pp 135-146... 

Johnson LE, Padilla DK (1996) Geographic spread of exotic species ecological lessons and opportunities from the invasion of the zebra mussel Dreissena polymorpha. Biol Conserv... 

Cope WG, Bartsch MR, Rada RG, Balogh SJ, Rupprecht JE, Young RD, Johnson DK (1999) Bioassessment of mercury, cadmium, polychlorinated biphenyls, and pesticides in the upper Mississippi river with zebra mussels (Dreissena polymorpha). Environ Sci Technol 33 4385-... 

Custer CM, Custer TW (1996) Food habits of diving ducks in the Great Lakes after the zebra mussel invasion. J Field Omithol 67 86-99... 

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