Infection by the cestode parasiteSchistocephalussp. and effects on diet, body condition and survival of sculpinsCottus aleuticusandCottus cognatus

Abstract

Sampling in Iliamna Lake, Alaska, U.S.A. revealed that a greater proportion of coastrange sculpins Cottus aleuticus were infected by the cestode Schistocephalus solidus than slimy sculpins Cottus cognatus (52 v. 23%), and infected C. aleuticus contained more cestodes than did C. cognatus (2·1 v. 1·3 per fish). Consumption of sockeye salmon Oncorhynchus nerka eggs (the primary diet item) was lower in fishes with cestodes, and a model based on cestode prevalence and age composition estimated higher rates of infection and parasite-associated mortality in C. aleuticus compared with C. cognatus.

Distinct evolutionary lineages of Schistocephalus parasites infecting co-occurring sculpin and stickleback fishes in Alaska

“…We drew inferences based on morphological, genetic and phylogenetic comparisons of parasites from all 4 fish species sampled from 2 lakes in different river drainages in southwest Alaska. This effort builds on prior investigations of the ecology (Quinn et al, 2012) and genetics (Sprehn et al, 2015) of S. solidus in threespine stickleback from Bristol Bay (southwest Alaska, USA) that led to detection of cryptic plerocercoids in slimy sculpin and coastrange sculpin from Iliamna Lake (Harmon et al, 2015). Initial examinations revealed that the cestodes in the 2 sculpin species exhibit more segments than those in threespine sticklebacks, consistent with the pattern reported for cestodes from cottids in Finland by Chubb et al (2006).…”

“…The number of fishes discovered to be intermediate hosts of Schistocephalus plerocercoids now includes freshwater sculpins (family Cottidae) from widely separated locations, including bullhead, Cottus gobio, in an Arctic river in Finland (Chubb et al, 2006); slimy sculpin, Cottus cognatus, in lakes of the Arctic region of Alaska, USA (V.B. Holland, unpublished MSc thesis, University of North Carolina at Greensboro, 2006), a lake of southwest Alaska (Harmon et al, 2015), Lake Michigan, USA (French and Muzzall, 2008) and the Athabasca River drainage, Alberta, Canada (Braicovich et al, 2020) and coastrange sculpin, Cottus aleuticus, in a lake of southwest Alaska (Harmon et al, 2015). Thus, multiple species of fishes are potentially susceptible to infection by Schistocephalus cestodes, including sticklebacks and sculpins that often co-occur in lake habitats (McPhail and Lindsey, 1970).…”

First Reports of Ligula intestinalis and a Schistocephalus sp. Infecting Small-Bodied Fish in New Brunswick, Canada

“…Whereas plerocercoid segment number (n = 113) is compatible with S. cotti (see Chubb et al, 2006 ), and despite their slimy sculpin host being congeneric with European bullhead (both Cottus species), French and Muzzall (2008) cautioned against species-level identification due to past challenges with accurate Schistocephalus identification. Harmon et al (2015) similarly concluded that only generic-level identification of Schistocephalus sp. plerocercoids was warranted for specimens from 2 Cottus species hosts (coastrange sculpins and slimy sculpins) in 1 Alaskan lake.…”

“…infecting coastrange sculpin, slimy sculpin, and bullhead ( Cottus spp.) as their second intermediate host ( Chubb et al, 2006 ; French and Muzzall, 2008 ; Harmon et al, 2015 ). Species-level identification of cestode plerocercoids is difficult due to their lack of distinctive morphological features, making molecular analyses necessary ( Van Steenkiste et al, 2015 ).…”