FIRST REPORT IN CANADA OF CERATONOVA GASTEROSTEA (CNIDARIA: MYXOZOA) IN THREESPINE STICKLEBACK GASTEROSTEUS ACULEATUS FROM THE FRASER RIVER, BRITISH COLUMBIA.

A survey of threespine stickleback (Gasterosteus aculeatus L.) and juvenile Chinook salmon (Oncorhynchus tshawytscha (Walbaum)) from the lower Fraser River, British Columbia, Canada and adjacent marine waters was conducted for the presence of myxozoan parasites of the genus Ceratonova Atkinson, Foott, and Bartholomew, 2014 (Bivalvulida, Ceratomyxidae). Quantitative polymerase chain reaction (PCR; small subunit ribosomal RNA gene) combined with conventional PCR and sequencing (ribosomal internal transcribed spacer region 1) detected Ceratonova gasterostea Atkinson, Foott, and Bartholomew, 2014 in 89 of 269 (33.

Parvicapsula pseudobranchicola in the northeast Pacific Ocean is rare in farmed Atlantic salmon Salmo salar despite widespread occurrence and pathology in wild Pacific salmon Oncorhynchus spp.

Background: Infection with the myxozoan parasite Parvicapsula pseudobranchicola causes disease in wild and farmed salmonids in Norway. In the northeast Pacific Ocean, the parasite has been reported in Pacific salmon Oncorhynchus spp. without evidence of disease.

Increased prevalence and severity of Kudoa thyrsites (Cnidaria: Myxosporea) in Atlantic salmon Salmo salar exposed to deeper seawater.

Kudoa thyrsites is a myxozoan parasite of marine fish with a global distribution. In British Columbia (BC), Canada, severe infections are associated with an economically significant degradation of fillet quality in farmed Atlantic salmon. Exposures to naturally occurring actinospores at a coastal research laboratory were used to test the hypothesis that the prevalence and severity of K.

Elevated Seawater Temperature and Infection with Exacerbate Complex Gill Disease in Farmed Atlantic Salmon () in British Columbia, Canada.

Gill disorders and diseases are emergent health concerns affecting marine-farmed salmon, for which the causal factors are poorly understood in British Columbia (BC), Canada. This study sought to describe and compare spatial and temporal patterns of infection with , the causal agent of amoebic gill disease, and visually assessed gill health scores in farmed Atlantic salmon. Gill tissue obtained during the Fisheries and Oceans Canada's Fish Health Audit and Intelligence Program (DFO-FHAIP) between 2016 and 2020 were screened for by qPCR.

Piscirickettsia salmonis shedding and tissue burden, and hematological responses during cohabitation infections in chum Oncorhynchus keta, pink O. gorbuscha and Atlantic salmon Salmo salar.

Background: Salmonid rickettsial septicemia is an emergent and geographically widespread disease of marine-farmed salmonids caused by infection with the water-borne bacterium Piscirickettsia salmonis. Very little is known about the route, timing, or magnitude of bacterial shedding from infected fish.

Methodology/principal Findings: A cohabitation challenge model was used to assess shedding from chum Oncorhynchus keta, pink O.

Development of a Piscirickettsia salmonis immersion challenge model to investigate the comparative susceptibility of three salmon species.

Piscirickettsia salmonis, the aetiological agent of salmonid rickettsial septicaemia (SRS), is a global pathogen of wild and cultured marine salmonids. Here, we describe the development and application of a reproducible, standardized immersion challenge model to induce clinical SRS in juvenile pink (Oncorhynchus gorbuscha), Atlantic (Salmo salar) and sockeye salmon (O. nerka).

Myosporidium ladogensis n. comb. in burbot Lota lota from Finland: fine structure and microsporidian taxonomy.

Infections with microsporidian parasites are described in skeletal muscle of burbot Lota lota from Lake Haukivesi, Finland. Infected myocytes contained spores within sporophorous vesicles (SPVs) in contact with host cell cytoplasm, similar to Pleistophora ladogensis in L. lota and smelt Osmerus eperlanus in western Russia and northern Germany.

Factors associated with severity of naturally occurring piscirickettsiosis in netpen- and tank-reared juvenile Atlantic salmon at a research aquarium in western Canada.

The opportunistic examination of factors associated with an outbreak of piscirickettsiosis (SRS) is described in Atlantic salmon Salmo salar post-smolts held in an open netpen or in tanks supplied with raw sea water at a research aquarium in western Canada. During the outbreak, seawater temperature was significantly higher and salinity significantly lower in the netpen compared with the tanks. Mortality in the netpen began approximately 3 weeks prior to that in the tanks, and cumulative mortality in the netpen (34%) was significantly higher than in the tanks (12%).

Host size influences prevalence and severity of Kudoa thyrsites (Cnidaria: Myxosporea) infection in Atlantic salmon Salmo salar.

Kudoa thyrsites is a cosmopolitan myxozoan parasite of marine fish. The infection causes an economically important myoliquefaction in farmed Atlantic salmon in British Columbia, Canada. Laboratory exposure of Atlantic salmon smolts to infectious seawater was used to test the hypothesis that infection with K.

Synergistic osmoregulatory dysfunction during salmon lice (Lepeophtheirus salmonis) and infectious hematopoietic necrosis virus co-infection in sockeye salmon (Oncorhynchus nerka) smolts.

While co-infections are common in both wild and cultured fish, knowledge of the interactive effects of multiple pathogens on host physiology, gene expression and immune response is limited. To evaluate the impact of co-infection on host survival, physiology and gene expression, sockeye salmon Oncorhynchus nerka smolts were infected with the salmon louse Lepeophtheirus salmonis (V-/SL+), infectious hematopoietic necrosis virus (IHNV; V+/SL-), both (V+/SL+), or neither (V-/SL-). Survival in the V+/SL+ group was significantly lower than the V-/SL- and V-/SL+ groups (p = 0.

Differential Effects of Adult Salmon Lice Lepeophtheirus salmonis on Physiological Responses of Sockeye Salmon and Atlantic Salmon.

The salmon louse Lepeophtheirus salmonis, a type of sea lice (family Caligidae), is enzootic in marine waters of British Columbia and poses a health risk to both farmed Atlantic Salmon Salmo salar and wild Pacific salmon Oncorhynchus spp. At the adult stage, sea lice infections can often result in severe cutaneous lesions in their salmonid hosts. To evaluate and compare the physiological consequences of adult L.

Acquired Protective Immunity in Atlantic Salmon Salmo salar against the Myxozoan Kudoa thyrsites Involves Induction of MHIIβ CD83 Antigen-Presenting Cells.

The histozoic myxozoan parasite causes postmortem myoliquefaction and is responsible for economic losses to salmon aquaculture in the Pacific Northwest. Despite its importance, little is known about the host-parasite relationship, including the host response to infection. The present work sought to characterize the immune response in Atlantic salmon during infection, recovery, and reexposure to After exposure to infective seawater, infected and uninfected smolts were sampled three times over 4,275 degree-days.

Effects of the vertically transmitted microsporidian Facilispora margolisi and the parasiticide emamectin benzoate on salmon lice (Lepeophtheirus salmonis).

Background: Microsporidia are highly specialized, parasitic fungi that infect a wide range of eukaryotic hosts from all major taxa. Infections cause a variety of damaging effects on host physiology from increased stress to death. The microsporidian Facilispora margolisi infects the Pacific salmon louse (Lepeophtheirus salmonis oncorhynchi), an economically and ecologically important ectoparasitic copepod that can impact wild and cultured salmonids.

Enhanced transcriptomic responses in the Pacific salmon louse Lepeophtheirus salmonis oncorhynchi to the non-native Atlantic Salmon Salmo salar suggests increased parasite fitness.

Background: Outcomes of infections with the salmon louse Lepeophtheirus salmonis vary considerably among its natural hosts (Salmo, Oncorhynchus spp.). Host-parasite interactions range from weak to strong host responses accompanied by high to low parasite abundances, respectively.

Sex-biased gene expression and sequence conservation in Atlantic and Pacific salmon lice (Lepeophtheirus salmonis).

Background: Salmon lice, Lepeophtheirus salmonis (Copepoda: Caligidae), are highly important ectoparasites of farmed and wild salmonids, and cause multi-million dollar losses to the salmon aquaculture industry annually. Salmon lice display extensive sexual dimorphism in ontogeny, morphology, physiology, behavior, and more. Therefore, the identification of transcripts with differential expression between males and females (sex-biased transcripts) may help elucidate the relationship between sexual selection and sexually dimorphic characteristics.

Differential modulation of resistance biomarkers in skin of juvenile and mature pink salmon, Oncorhynchus gorbuscha by the salmon louse, Lepeophtheirus salmonis.

Juvenile pink salmon larger than 0.7 g reject the sea louse, Lepeophtheirus salmonis, and are considered resistant to the infection. Robust innate defense responses in the skin contribute to the observed resistance.

Specific PCR for Myxobolus arcticus SSU rDNA in juvenile sockeye salmon Oncorhynchus nerka from British Columbia, Canada.

A PCR for the specific detection of the salmon brain parasite Myxobolus arcticus (Pugachev and Khokhlov, 1979) was developed using primers designed to amplify a 1363 base pair fragment of the small subunit rDNA. The assay did not amplify DNA from 5 other Myxobolus species or from 7 other myxozoan species belonging to 5 other genera. For juvenile sockeye salmon Oncorhynchus nerka (Walbaum) collected from Chilko Lake, British Columbia (BC), Canada, in 2011, the prevalence by PCR was 96%, in contrast to 71% by histological examination of brain tissue.

Transcriptomic responses to emamectin benzoate in Pacific and Atlantic Canada salmon lice Lepeophtheirus salmonis with differing levels of drug resistance.

Salmon lice Lepeophtheirus salmonis are an ecologically and economically important parasite of wild and farmed salmon. In Scotland, Norway, and Eastern Canada, L. salmonis have developed resistance to emamectin benzoate (EMB), one of the few parasiticides available for salmon lice.

Signatures of resistance to Lepeophtheirus salmonis include a TH2-type response at the louse-salmon interface.

Disease outbreaks with the salmon louse Lepeophtheirus salmonis cause significant economic losses in mariculture operations worldwide. Variable innate immune responses at the louse-attachment site contribute to differences in susceptibility among species such that members of Salmo spp. are more susceptible to infection than those of some Oncorhynchus spp.

Detection of a parasitic amoeba (Order Dactylopodida) in the female gonads of oysters in Brazil.

The impacts of oocyte parasites on the reproductive success of molluscs are largely unknown. In this study, we evaluated the presence of gonad parasites in 6 species of marine bivalve molluscs native to southern Brazil. Cultured bivalves included the mangrove oyster Crassostrea gasar (sometimes called C.

Comparative transcriptomics of Atlantic Salmo salar, chum Oncorhynchus keta and pink salmon O. gorbuscha during infections with salmon lice Lepeophtheirus salmonis.

Background: Salmon species vary in susceptibility to infections with the salmon louse (Lepeophtheirus salmonis). Comparing mechanisms underlying responses in susceptible and resistant species is important for estimating impacts of infections on wild salmon, selective breeding of farmed salmon, and expanding our knowledge of fish immune responses to ectoparasites. Herein we report three L.

Sea lice infestations on juvenile chum and pink salmon in the Broughton Archipelago, Canada, from 2003 to 2012.

Juvenile pink salmon Oncorhynchus gorbuscha and chum salmon O. keta were sampled by beach or purse seine to assess levels of sea lice infestation in the Knight Inlet and Broughton Archipelago regions of coastal British Columbia, Canada, during the months of March to July from 2003 to 2012. Beach seine data were analyzed for sea lice infestation that was described in terms of prevalence, abundance, intensity, and intensity per unit length.

Modeling parasite dynamics on farmed salmon for precautionary conservation management of wild salmon.

Conservation management of wild fish may include fish health management in sympatric populations of domesticated fish in aquaculture. We developed a mathematical model for the population dynamics of parasitic sea lice (Lepeophtheirus salmonis) on domesticated populations of Atlantic salmon (Salmo salar) in the Broughton Archipelago region of British Columbia. The model was fit to a seven-year dataset of monthly sea louse counts on farms in the area to estimate population growth rates in relation to abiotic factors (temperature and salinity), local host density (measured as cohort surface area), and the use of a parasiticide, emamectin benzoate, on farms.

Transcriptomics of coping strategies in free-swimming Lepeophtheirus salmonis (Copepoda) larvae responding to abiotic stress.

The salmon louse Lepeophtheirus salmonis is a marine ectoparasite of wild and farmed salmon in the Northern Hemisphere. Infections of farmed salmon are of economic and ecological concern. Nauplius and copepodid salmon lice larvae are free-swimming and disperse in the water column until they encounter a host.

The diversity of microsporidia in parasitic copepods (Caligidae: Siphonostomatoida) in the Northeast Pacific Ocean with description of Facilispora margolisi n. g., n. sp. and a new Family Facilisporidae n. fam.

Three distinct microsporidia were identified from parasitic copepods in the northeast Pacific Ocean. Sequencing and phylogenetic analysis of a partial small subunit ribosomal RNA gene (SSU rDNA) sequence identified a genetically distinct variety of Desmozoon lepeophtherii from Lepeophtheirus salmonis on cultured Atlantic salmon Salmo salar, and this was confirmed by transmission electron microscopy. Phylogenetic analysis resolved the SSU rDNA sequence of the second organism in a unique lineage that was most similar to microsporidia from marine and brackish water crustaceans.