The quagga mussel ( Dreissena rostriformis bugensis Andrusov, 1897) – another Ponto-Caspian dreissenid bivalve in the southern Baltic catchment: the first record from the Szczecin Lagoon ☆

摘要

Summary In 2014, a non-indigenous dreissenid bivalve, the quagga mussel ( Dreissena rostriformis bugensis Andrusov, 1897) was for the first time recorded in the Szczecin Lagoon. This was also the first record of the species in the Baltic Sea catchment. The quagga mussel was found to accompany the zebra mussel ( Dreissena polymorpha ), a non-indigenous bivalve already firmly established in the Lagoon. As indicated by the new immigrant's estimated abundance (4000.0?±?355.44?ind.?m?2) and the zebra mussel to quagga mussel abundance ratio (about 60:40), the immigration of D. rostriformis bugensis to the Lagoon can be regarded as successful. The quagga mussel has already formed a strong and reproducing population which co-occurs with that of the zebra mussel in the area. Keywords Dreissena rostriformis bugensis ; Baltic Sea ; Szczecin Lagoon ; Invasive species prs.rt("abs_end"); 1. Introduction In addition to the zebra mussel ( Dreissena polymorpha Pallas, 1771), the quagga mussel ( Dreissena rostriformis bugensis Andrusov, 1897) is another Ponto-Caspian dreissenid bivalve which has colonised freshwater reservoirs of Europe and North America ( Karatayev et al., 2015 , Nalepa and Schloesser, 2013 , Orlova et al., 2004 , Orlova et al., 2005 and Zhulidov et al., 2010 ). Dreissena rostriformis bugensis is a species native for the entire area of the southern Bug River and Dnieper River catchment in Ukraine ( Orlova et al., 2004 and Orlova et al., 2005 ). The bivalve began expanding its range in eastern Europe as late as post 1940, when the first dam reservoirs were built on the Dnieper River. Between 1940–1990, D. rostriformis bugensis was seen to expand in three major direction: to the north, along the cascade of the Dnieper River dam reservoirs; to the east, via the River Don system, and thence to the north, through the reservoirs on the Volga; and to the north-west, through the Dniester River ( Mills et al., 1996 , Orlova et al., 2004 , Orlova et al., 2005 and Zhulidov et al., 2010 ). In 2004, D. rostriformis bugensis was recorded in the Romanian part of the Danube River system ( Micu and Telembici, 2004 and Popa and Popa, 2006 ). Concurrently, in 1989, the species was first recorded in the Laurentian Great Lakes of North America ( Benson, 2013 and Mills et al., 1993 ). The quagga mussel invasion there closely followed that of the zebra mussel so the two species have been seen to expand their range in tandem ( Benson, 2013 and Karatayev et al., 2015 ). At present, the two species continue colonising the North American waters. In most of the newly colonised areas, the two congeners co-occur, but their within-water body distributions differ ( Karatayev et al., 2015 and Nalepa et al., 2010 ). The zebra mussel seems to be a more successful coloniser of the two, the number of water bodies it has colonised being 17 times higher than the number of water bodies colonised by the quagga mussel ( Karatayev et al., 2015 ). In western Europe, the beginning of D. rostriformis bugensis expansion dates to 2006 when the species was recorded in the Rhine delta, in Hollandsch Diep in the Netherlands ( Molloy et al., 2007 and Schonenberg and Gittenberger, 2008 ). Subsequently, the species colonised the rivers Rhine and Mose ( Haybach and Christmann, 2009 , Imo et al., 2010 , Karatayev et al., 2015 , Matthews et al., 2014 and Van der Velde and Platvoet, 2007 ). In 2007, the species was spotted in the River Main, a River Rhine tributary in Germany ( Martens et al., 2007 and Van der Velde and Platvoet, 2007 ), to be found – in 2011 – in the French part of the Mosel ( Bij de Vaate and Beisel, 2011 ). In 2014, the species was first reported from the United Kingdom ( Aldridge et al., 2014 ). At present, the quagga is observed to be spreading rapidly in inland waters of western Europe ( Karatayev et al., 2015 and Matthews et al., 2014 ). The western European population's site closest to the Baltic Sea catchment is in the Elbe, that of the eastern European population closest to the Baltic Sea inhabiting the Prypyat River ( Schoell et al., 2012 ). Here, we are reporting on finding the quagga mussel in the Szczecin Lagoon (Odra River estuary, southern Baltic Sea), thus providing the first record of the species in the Baltic Sea catchment. The Szczecin Lagoon ( Fig. 1 ), divided into two parts: the Small Lagoon (Kleines Haff) located almost entirely within Germany and the Great Lagoon (Wielki Zalew) on the Polish side of the Polish-German border bisecting the Lagoon, forms a major part of the River Odra estuarine system. Fed by the Odra River from the south and connecting with the Pomeranian Bay (southern Baltic Sea) in the north, the Lagoon is a typical brackish transitional water body the hydrographic regime of which is shaped by an interplay of fresh water discharged by the Odra River and the periodic intrusions of about 7?PSU sea water from the Baltic Sea. As a result, the Lagoon's salinity ranges from 0.3 to 4–5?PSU and average