An assessment of lesions in bay scallops Argopecten irradians attributed to Perkinsus karlssoni (Protozoa, Apicomplexa (original) (raw)
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Diseases of Aquatic Organisms, 1996
Since 1988 growers of bay scallop Argopecten iively. Bay scallop growers in recent years have expeirradjans in China have been experiencing mortality in their rlenced problems with increasing mortality in their poorly cultured scallops, Scallop mortality was first noticed in apparently began near Qingdao and has since spread to other areas of Shandong and Liaoning provinces. Samples of cul-the Yang Ma DaO hatchery in lg8*. tured scallops were collected from several growing areas in scallop mortalities spread into other areas of the Shanthese provinces and analyzed by histological methods for donq peninsula. In 1989 mortalities occurred in Jiao-" . pathogens. An unidentified haplosporidian parasite was ob-=hou in 1990 in ~~~~h~~ and ~~i~~ in 1991 in served in a high proportion of scallops from two of the stocks examined. Most infections were of low intensity, but one the Jiaonan region, and in 1992 in Jimo, Penglai and heavy infection was also observed. Only plasmodia stages Laizhou Bay (Shandong province) and in Dalian were observed; they occurred intercellularly In connective (Liaoning province). Currently, there is no adequate tissues throughout the scallops. Plasmodia were spherical to documentation of the mortality rate, but scallops usu. oval, varied from 4 0 to 17.0 pm in diameter and contained ally die in the spring of each year, somewhat after from 2 to 18 nuclei. Absence of spores prevented generic assignment of the parasite. The source and pathogenicity of 'pawning. little research has been ' Onthe haplosporidian could not be assessed without additional ducted on the cause of mortality, it has been attributed research. No other microbial parasites (i.e. rickettsia-like, chlamydia-like or kidney coccidia) were observed in any of the scallops examined.
An apicomplexan parasite drives the collapse of the bay scallop population in New York
Scientific Reports
The bay scallop, Argopecten irradians, represents a commercially, culturally and ecologically important species found along the United States’ Atlantic and Gulf coasts. Since 2019, scallop populations in New York have been suffering large-scale summer mortalities resulting in 90–99% reduction in biomass of adult scallops. Preliminary investigations of these mortality events showed 100% prevalence of an apicomplexan parasite infecting kidney tissues. This study was designed to provide histological, ultrastructural and molecular characteristics of a non-described parasite, member of the newly established Marosporida clade (Apicomplexa) and provisionally named BSM (Bay Scallop Marosporida). Molecular diagnostics tools (quantitative PCR, in situ hybridization) were developed and used to monitor disease development. Results showed that BSM disrupts multiple scallop tissues including kidney, adductor muscle, gill, and gonad. Microscopy observations allowed the identification of both intra...
Environmental Microbiology, 2006
Phenotypic scrutiny on the life cycle of Icthyodinium chabelardi ( Perkinsoide chabelardi n. gen.) based on ultrastructural techniques, and molecular phylogenetic analysis of RNA gene sequences, were carried out in order to elucidate the taxonomic position of this parasite. The absence of plastid, presence of trichocysts, and chromosomes or chromatin condensed and low in number, suggested that this protozoan could be considered a dinoflagellate syndinial parasite. However, the life cycle, schizogonic divisions and structure of schizonts inside the host, the nuclei without the typical dinoflagellate appearance, presence of rhoptrias-like structures, a possible pseudoconoid, and the biflagellated spore, resembled those of the genus Perkinsus. Phylogenetic analysis of genes transcribing for the RNA forming the small subunit and the large subunit suggests that this parasite has an ambiguous evolutionary position within the group formed by dinoflagellates, perkinsids and syndinials. Because of differences with dinoflagellates and similarities with perkinsids, we propose to change the generic name to P. chabelardi n. gen. High stationary infection prevalence on Sardina pilchardus eggs was observed. This protozoan parasite caused the death of all the infected sardine eggs, and there-fore a high impact in the recruitment of this fishery in the Atlantic coast is expected.
Diseases of Aquatic Organisms, 2005
A study was conducted into the health status of natural populations of the venerid clam Pitar rostrata from Uruguay. Perkinsus sp. was detected in 22% of the clams. Severe hemocytic infiltration was detected in the tissues parasitized by this protozoan parasite. The sequencing of the ITS-5.8S gene cluster of the parasite confirmed that it belonged to the Perkinsus olseni species. Rickettsia or Chlamidia-like organisms were also found, with a prevalence of 11%, although without apparent host reaction; an unidentified species of Coccidia was found in the nephridia of 78% of the clams, with the intensity of infection ranging from moderate to high. A gregarine, Nematopsis-like organism was observed mainly in the epithelial cells of the intestine, without host response and with a prevalence of 56%. Of the metazoan parasites, trematodes were found in 11% of the individuals analyzed.
Perkinsosis in molluscs: A review
Aquatic Living Resources, 2004
The genus Perkinsus includes protistan parasites infecting marine molluscs throughout the world, some of which are associated with mass mortalities. Life cycle involves vegetative proliferation within the host, by which a cell named trophozoite undergoes successive bipartitioning. Other stages have been observed in vitro or in vivo, depending on the species: hypnospore, zoosporangium and zoospore. Molecular taxonomy supports a close affinity between dinoflagellates and Perkinsus spp. Six species of Perkinsus are currently considered valid: P. marinus, P. olseni, P. qugwadi, P. chesapeaki, P. andrewsi and P. mediterraneus. Histology and, above all, incubation of host tissues in Ray's fluid thioglycollate medium (RFTM) are classic diagnostic methods. In addition, more sensitive and quicker molecular diagnostic techniques based on either immunoassays or PCR have been developed for Perkinsus spp. Epizootiological studies have shown a marked influence of water temperature and salinity on P. marinus infection in oysters Crassostrea virginica, thus determining parasite geographical range and temporal disease dynamics (seasonality).
Polar biology, 2009
The importance of epibiosis in Antarctic benthic communities is highlighted here considering the spe-ciWc diversity of sponges living on shells of the scallop Adamussium colbecki and on spines of the cidaroid urchin Ctenocidaris perrieri. Scallops are from three diVerent areas along the Victoria Land [Tethys Bay (TB), New Harbour (NH), Dunlop Island (DI)], while cidaroid urchins are from NH but not present in the two other stations. Homaxinella balfourensis is the commonest species both on the scallops and cidaroid urchins. Other common species on scallops are Myxilla (Myxilla) asigmata, Lissodendoryx (Ectyodoryx) nobilis and Iophon unicorne at NH, Iophon unicorne at DI, and Iophon radiatum, Haliclona sp. 1, Iophon unicorne and Lissodendoryx (Ectyodoryx) nobilis at TB. The highest number of sponge species we found on a single scallop was ten and the sample was collected at NH. On the spines of C. perrieri, Isodictya erinacea, Iophon unicorne and Haliclona (Rhizoniera) dancoi are present too. A. colbecki and C. perrieri, generally living on soft bottoms, represent important substrata for several sponge species. In this way, sponges may increase their dispersal exploiting valves and spines as stepping stones.