From port to port: the invasive bivalve Mytilopsis cf. sallei (Dreissenidae) is confirmed in southeastern Brazil

Abstract

ABSTRACT This study records a new introduction of the estuarine, invasive bivalve Mytilopsis cf. sallei in southeastern Brazil. The new record lies close to the largest port of the country (the Port of Santos, in São Paulo state), raising serious concerns related to the probable expansion of this bivalve in future years. Two out of five sampling stations showed live specimens of M. cf. sallei in the soft sediment, in sites with polluted waters and salinity below 20 ppt, reaching a maximum abundance of 1983 specimens/m2. According to COI evidence, two lineages of M. cf. sallei are present in the region, one of which was previously recorded from northeastern Brazil (where it is probably exotic), and another previously recorded from Florida (native) and Asia (exotic). Potential sources for the introduction are discussed, as well as the role of ballast water vs. biofouling as vectors. Because adults of M. cf. sallei are tolerant to long periods in marine waters, it is possible that biofouling from distant sources contributed to this introduction. In order to enable a robust mitigation plan, a complete spatial evaluation for the presence of this bivalve should be conducted in the Santos Estuary.