FIRST REPORT OF Perkinsus chesapeaki IN DELAWARE BAY RAZOR CLAMS, Tagelus plebeius

The protozoan oyster pathogen Perkinsus marinus has infected populations of Crassostrea virginica along the Atlantic and Gulf Coasts of North America since at least the 1940s. Until recently, it was the only Perkinsus sp. pathogen known to exist in the region. During the past decade, independent laboratories have reported P. chesapeaki (now synonymous with P. andrewsi) in softshell clams (Mya arenaria), stout razor clams (Tagelus plebeius), and baltic clams (Macoma balthica) from Chesapeake Bay. Laboratory studies have shown that P. marinus can infect these clam hosts and that P. chesapeaki can infect eastern oysters. Field surveys using PCR assays have documented apparent cross-host infections, and some co-infections by both Perkinsus spp. The standard diagnostic assay for Perkinsus sp. infections is Ray’s Fluid Thioglycollate Medium (RFTM) assay, but does not distinguish among species. Observations of cross-infectivity potential, and of co-infections, create some potential problems in diagnosing perkinsiosis in molluscan shellfish. Furthermore, the broad distributions of stout razor clams, soft shell clams and baltic clams that overlap with eastern oysters’ causes uncertainty about which pathogen species may infect which hosts. Here, we report the first observations of a Perkinsus spp. in stout razor clams from the New Jersey portion of lower Delaware Bay, USA.