Limited success of the non-indigenous bivalve clam Rangia cuneata in the Lithuanian coastal waters of the Baltic Sea and the Curonian Lagoon

Abstract

Summary: The gulf wedge clam, common rangia Rangia cuneata, with a native origin in the Gulf of Mexico has spread to north European brackish and freshwaters. This semitropical species is able to survive in conditions of low winter temperatures in boreal environment of the Baltic Sea. Its expansion within lagoons and sheltered bays in the southern and eastern parts of the Baltic Sea appears to be with natural spread and its discontinuous distribution is likely to have been with shipping, either within ballast water or as settled stages transported with dredged material. In this account, we report on the occurrence of R. cuneata in Lithuanian waters. We compare habitats of the common rangia in the Curonian Lagoon and in the exposed coastal waters of the Baltic Sea. We notice high mortality of the species in the Lithuanian waters in comparison to the neighboring Vistula Lagoon. Based on finding of small specimens of R. cuneata attached to the spiked watermilfoil Myriophyllum spicatum, we indicate a risk of local spread with movements of fishing equipment and snagged plants on anchors or boat trailers removed from the water. We discuss the possibility of further spread of the common rangia to similar environments in the Baltic Sea and elsewhere in Europe. Keywords: Semitropical bivalve, Coastal lagoon, Exposed coast, Winter conditions, Ballast water, Natural spread.