Six types of pathogenic endoparasites in an economically important fish, spotted seatrout Cynoscion nebulosus, were studied in order to test whether prevalence of infection and assemblage richness varied with season, host sex, host size, or host age. Fish were collected from South Carolina estuaries, USA, over 12 months (n = 216; total lengths 15-663 mm). They were screened histologically for presence of Henneguya cynoscioni (Myxozoa) and Cardicola spp. (Digenea) in the heart, Kudoa inornata (Myxozoa) in the skeletal muscle, Sinuolinea dimorpha (Myxozoa) in the urinary system, Ichthyophonus sp. (Mesomycetozoea) in the kidney, and an unidentified microsporidian in the liver. Prevalence of infection was 29.8, 38.6, 47.2, 41.2, 13.6, and 2.8%, respectively. All factors had significant, but varying effects on the parasites. Parasite infections were more prevalent in winter than other seasons for Cardicola spp. and H. cynoscioni, more prevalent in winter and spring for Ichthyophonus sp., and more prevalent in male fish than female fish for K. inornata, S. dimorpha, and Ichthyophonus. Prevalence of infection by the three myxosporeans and Cardicola spp. increased with fish length, whereas prevalence of Ichthyophonus increased with length among young fish, but decreased with length among older fish. None of the factors affected the liver microsporidian, although statistical power was low due to its rareness. Assemblage richness varied between 0 and 5, was greater during winter and in male fish, and increased with fish length and fish age. Our results demonstrate that spotted seatrout are commonly co-infected by multiple pathogenic endoparasites, suggesting these parasites likely play an import role in controlling fish population numbers.

• Keywords
• Aporocotylidae, Histology, Ichthyosporea, Myxozoa, Richness, Sciaenidae,
• MeSH
• Estuaries * MeSH
• Fish Diseases epidemiology   parasitology   MeSH
• Parasitic Diseases, Animal epidemiology   parasitology   MeSH
• Seasons MeSH
• Fishes parasitology   MeSH
• Animals MeSH
• Check Tag
• Male MeSH
• Female MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH
• Geographicals
• South Carolina epidemiology   MeSH

UNLABELLED: Myxosporeans (Myxozoa), microscopic metazoan parasitic organisms, are poorly studied in the Arctic region. Our survey of benthic and pelagic fish (n = 234) collected in Isfjorden (Svalbard, Norway) together with detailed morphological and molecular examination revealed the presence of nine myxosporean species. We compared observed myxosporean diversity with diversity documented in regions close to the Arctic and revealed that water depth rather than geographic distribution is an important factor influencing myxosporean fauna. WE DESCRIBE THREE NEW MYXOSPOREAN SPECIES: Zschokkella siegfriedi n. sp. from kidney of Boreogadus saida, Parvicapsula petuniae n. sp. from the urinary bladder of Gymnocanthus tricuspis, and Sinuolinea arctica n. sp. from the urinary bladder of Myoxocephalus scorpius. We characterise Latyspora-like organism from kidney of Clupea harengus. We provide new data for Ceratomyxa porrecta, Myxidium gadi, Myxidium finnmarchicum, Schulmania aenigmatosa, and Parvicapsula irregularis comb. nov. The phylogenetic analyses including the newly obtained SSU and LSU rDNA data revealed that most of the species studied cluster in the marine urinary clade within the marine myxosporean lineage. Newly obtained sequences including the first molecular data for the member of the genus Schulmania, substantially enriched the Zschokkella subclade. C. porrecta and the two Myxidium species cluster within the Ceratomyxa and marine Myxidium clade, respectively. Newly described species, Z. siegfriedi n. sp., was revealed to be morphologically indistinguishable but genetically diverse from Zschokkella hildae known from numerous gadid fish. Therefore, we consider Z. siegfriedi to be a cryptic myxosporean species that might be misidentified with Z. hildae. A Latyspora-like organism was found to be taxonomically problematic due to its suture line and its distant phylogenetic position from the type species Latyspora scomberomori did not allow us to assign it to the genus Latyspora. Based on an increased taxon sampling and SSU + LSU rDNA-based phylogeny, evolutionary trends within the marine urinary clade are investigated.

• Keywords
• Arctic, Marine urinary clade, Myxosporea, Phylogeny, Schulmania, Zschokkella,
• Publication type
• Journal Article MeSH