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INTRODUCTION
Say's mud crab Dyspanopeus sayi (S.I. Smith, 1869) is native to the Atlantic coast of North America, from Nova Scotia to the Florida Keys, where it is one of the most common and abundant mud crab species (Williams, 1984; Nizinski, 2003). It is a euryhaline species which lives in estuaries and shallow coastal sea and can complete its life cycle in estuarine waters with salinities of 9-11 psu, possibly even lower (Dittel & Epifanio, 1982; Newell et al., 2007). It is also eurythermic, ceasing feeding and burying for overwintering only at water temperatures below 3-5°C (Gibbons, 1984) and tolerates pollution well (Mizzan, 1999).
The first recorded introduction outside the species' native range dates from 1960, when D. sayi was identified in Britain from artificially warmed docks in Swansea, Wales (Naylor, 1960). The species has become well established in several British estuaries and coastal areas (Ingle, 1980; Hayward & Ryland, 1995) and is apparently spreading outside Britain, as it has been recently collected from the southern North Sea off the French and Dutch coasts (Vaz et al., 2007).
Elsewhere in Europe D. sayi was introduced in Venice Lagoon, probably in 1978-1979 (Mizzan, 1995) although it was recorded later, when it was already widespread and abundant throughout the lagoon (Froglia & Speranza, 1993). Since then D. sayi has become the dominant crab in the Venice and Marano Lagoons (Mizzan, 1995, 1998, 1999; Mizzan et al., 2005) and has been slowly spreading south along the Adriatic coast of Italy: Valli di Comacchio and Po River Delta (ICES, 2005) and Varano Lagoon in Apulia (Florio et al., 2008).
The biology of Say's mud crab is well studied in the United States, especially in relation to its importance as a predator of both wild and cultured juvenile shellfish (Flagg & Malouf, 1983; Strieb et al., 1995). Its predatory behaviour and impact on the native malacofauna, as well as prey preference between cultured and alien invasive bivalves were studied in the Adriatic Sea (Mizzan, 1998; Mistri, 2004).
In the present paper the presence of Dyspanopeus sayi is documented from the Romanian Black Sea. This is the first record of the species in the Black Sea.
MATERIALS AND METHODS
The...