Invasive Species Compendium

Detailed coverage of invasive species threatening livelihoods and the environment worldwide

Abstract

A comparison of the parasite and symbiont fauna of cohabiting native (Protothaca staminea) and introduced (Venerupis philippinarum and Nuttalia obscurata) clams in British Columbia.

Abstract

Native littleneck clams (Protothaca staminea), Manila clams (Venerupis philippinarum, inadvertently introduced in the 1930s), and varnish clams (Nuttallia obscurata, inadvertently introduced in the 1980s and 1990s) were collected from the same microsite at two different locations and examined for parasites and symbionts using histology and light microscopy. Varnish clams are currently being assessed for their long-term fisheries potential but there is little knowledge of their parasite and symbiont fauna. This study initiates the documentation of parasites and symbionts of varnish clams and adds to the continuing documentation of organisms found within native littleneck clams and Manila clams. Host exposure to potential parasites and symbionts that were prevalent in at least one of the clam species was assumed to be similar for all clams due to their close proximity. This close association in the natural environment allowed for the comparison of host specificity and response of the clams to multiple invasive species. All three of the clam species had a different assemblage of parasites and this pattern was mostly consistent for both sites. Host preferences of each type of parasite or symbiont were also consistent between sites and they were often restricted to a single host species. The most common parasites of varnish clams were Nematopsis-like spores, pea crabs (Pinnixa faba) and parasitic copepods (Mytilicola sp.) and less frequently a turbellarian inhabiting the kidney tubule. An undocumented eimeriorin-like kidney coccidian was found in 4% of Manila clams and two previously undescribed inclusions bodies were found in native littleneck clams at low frequencies.