Invasive non-native species (INNS) are expanding their geographic range due to climate change, maritime traffic (primary route) and aquaculture (secondary route), resulting in the potential spread of microbes associated with them. Few studies have investigated the INNS-Pathogen phenomenon. In this study, marine invertebrate species (native and INNS) were sampled monthly over three months and screened by PCR for ostreid herpesvirus-1 microVar (OsHV-1 μVar) and Vibrio bacteria. Both pathogens are negatively associated with bivalve aquaculture globally. Samples sites included a shipping port, an oyster farm, a marsh nature reserve and a riverine site.
Crustacea, Mollusca, Polychaeta, Tunicata and Porifera were sampled. 54.3% (n = 319/588) including all taxa and sample sites were positive for Vibrio spp. The first detection of Vibrio salmonicida associated with Atlantic salmon Salmo salar was detected in the INNS beaked barnacle Austrominius modestus. OsHV-1 μVar (7.7 %, 45/588) was detected in Crustacea, Mollusca and Polychaeta at non-culture sites and in mussels Mytilus spp. at a much lower temperature (average SST 11.25°C) than previously recorded. The shipping port had the highest diversity of Vibrio spp. and detection of OsHV-1 μVar. Over half (51.1%) of “recently dead” shore crabs Carcinus maenas had either pathogen detected compared to 29.4% of living crabs. OsHV-1 μVar detection was significantly higher in dead crabs (24.4%) compared to living crabs (5.9%). Findings from this study contribute a better understanding of the role of estuarine native and INNS as vectors/carriers of pathogens, and how the spread of INNS might facilitate the spread of pathogens.