Thomas K. Sawyer

A new species of Paramoeba (Amoebida, Paramoebidae) parasitic in the crab Callinectes sapidus☆

Abstract Paramoeba sp. Sprague and Beckett, 1966 , is compared with Paramoeba eilhardi Schaudinn 1896, the type and only presently recognized species in the genus, and found to be distinct. The name Paramoeba perniciosa sp. n. is proposed. Distinctive characters of this species are its parasitic habit, its failure to survive in common culture media, its relatively small size, and its linguiform lobopodia.

A molecular approach to the phylogeny of Acanthamoeba

Isoenzyme electrophoresis of three different enzyme systems was used to compare 71 strains assigned to the 15 currently recognized species of Acanthamoeba. A phylogenetic (cladistic) analysis of the zymograms indicated an arrangement of strains in 15 distinguishable lineages, but not all corresponding to current taxonomic assignments. Five of the groups corresponded to the recognized species A. castellanii, A. culbertsoni, A. griffini, A. lenticulata and A. royreba. But none of these groups consisted of only strains which had been previously assigned to each respective species. The type-equivalent strains for two species, A. hatchetti and A. tubiashi, were not closely aligned to any other strain and thus are considered to be monotypic. Strains of A. triangularis, A. astronyxis and A. palestinensis occurred together in a single group suggesting possible synonymy; however, on morphologic criteria, the strains assigned to these species are readily distinguishable. Strains assigned to A. polyphaga and A. rhysodes were interspersed throughout the other species groups. The strains of these two species were either misidentified or the species could not be recognized. Two groups previously not recognized as unique formed distinctive clusters which could be considered as new species. The analysis also made it possible to place strains which had previously been identified only to genus into species complexes. These results therefore suggest that previous criteria which have been used to classify Acanthamoeba are not adequate for fully resolving taxa at the species level.

An isonema-like flagellate (Protozoa: Mastigophora) infection in larval geoduck clams, Panope abrupta

Abstract Cultured geoduck clam ( Panope abrupta ) larvae were naturally infected with an Isonema -like flagellate. Free-swimming larval clams were initially infected by flagellates that penetrated the mantle and proliferated within the coelom. Larvae with heavy infections accumulated on the tank bottoms and ultimately died. The protozoan was identified as an Isonema -like flagellate based primarily on the presence of a distinctive ingestion apparatus composed of a microtubule complex, the presence of large, peripherally oriented mitochondria with sparse cristae, subplasmalemmal microtubules, the lack of a pellicle, short flagella, and pronounced metaboly. This is the first report of an invasive, pathogenic Isonema and the first report of a protozoan disease of a larval bivalve mollusc.

Distribution and possible interrelationships of pathogenic and nonpathogenicAcanthamoeba from aquatic environments.

Among the more recently discovered agents of human disease are small, free-living amebae belonging to the generaNaegleria andAcanthamoeba. An overview of the distribution ofAcanthamoeba in recent surveys of the near shore waters of the northeastern United States is presented. There appears to be a particular association between the presence ofAcanthamoeba in marine sediments and the sites of oceanic sludge dumping. Amebae belonging to the genusNaegleria have not been isolated from these marine sediments which routinely yieldedAcanthamoeba. Starch gel electrophoretic analysis of enzymes suggests that some isolates ofAcanthamoeba from oceanic sludge dump-sites are not members of previously recognized pathogenic species.

Hemocyte values in healthy blue crabs, Callinectes sapidus, and crabs infected with the amoeba, Paramoeba perniciosa

Abstract Hemolymph samples were collected from 156 blue crabs, Callinectes sapidus , in Chincoteague Bay, Virginia, during the summer of 1968. Stained smears of hemolymph from each of the crabs showed that 11 were parasitized with Paramoeba perniciosa . Hemolymph from heavily parasitized crabs was cloudy and often failed to coagulate, whereas hemolymph from uninfected crabs was clear and coagulated immediately upon extravasation. Hemocytometer counts from the uninfected crabs ranged from 4,000 to 128,000 hemocytes per mm 3 of hemolymph (mean, 52,619) and 85% of them were within a range of 10,000–70,000. The 11 infected crabs had 3,750 to 238,000 cells per mm 3 and microscopic examinations of stained smears of four of them showed that 3–100% of the cells were amoebae. Four types of hemocytes, two hyaline and two granular, were recognized on smears of uninfected hemolymph stained with Giemsa stain. Approximately 50–85% of the cells were hyaline and 15–50% were granular. The percentage composition of hyaline and granular hemocytes was similar in parasitized crabs, but the number of infected crabs was not large enough to permit a conclusion on the influence of parasitism on the counts.

A study of metal concentrations in relation to gill color and pathology in the rock crab

Gills of adult rock crabs,Cancer irroratus Say, collected near a sewage disposal site in the New York Bight apex were analyzed for copper, lead, cadmium, and silver. One gill from each animal was processed for histologic study to document pathological conditions within the tissues, and the presence or absence of fouling organisms on gill surfaces. Comparisons are made between metal concentrations in rock crab gills and published data on crustaceans from other locations.

Gill fouling and parasitism in the rock crab, Cancer irroratus say

Abstract Rock crabs, Cancer irroratus, were examined grossly and microscopically to estimate the influence of molting activity, geographical source and seabottom sediments on gill color, carapace color and tissue pathology. Collections were made from deepwater stations (20–55 m) in the Hudson Shelf Valley near dredge- and sewage-sludge disposal sites in the New York Bight apex, and from nearshore waters near Boothbay Harbor, Maine. Extensive gill blackening was noted in up to 30 % of the crabs from the New York stations when all specimens were in the intermolt condition. Blackening was not noted in intermolt crabs collected in Maine. Carapace blackening was present in up to 79 % of the New York crabs but absent in those from Maine. Severe blackening was attributed to direct contact of Cancer irroratus with blackened, highly organic sediments in the Hudson Shelf Valley. Fouling microorganisms on gill epicuticle included bacteria, diatoms, stalked ciliates, amoebae, flagellates and copepods. Bacteria, diatoms, amoebae and flagellates were common on crab gills from both locations. Ciliates and copepods counted in histological sections were considerably fewer in crabs from the New York stations than in those from Maine. Melanized nodules (hemocyte clumps) were present in gill tissue in up to 58 % of the New York crabs and in up to 68 % of Maine crabs. Unidentified microsporidans were found in up to 55 % of the New York specimens and in less than 2 % of those from Maine. Histological data accumulated since 1975 are summarized to provide a list of endoparasites, polychaete worms and barnacles observed in Cancer irroratus from the northeastern United States. Gill blackening, but not parasitism or microbial fouling, proved to be the best indicator or monitoring the effects of ocean dumping on the health of a benthic crustacean species.