title: The occurrence of Echinorhynchus salmonis Müller, 1784 in benthic amphipods in the Baltic Sea.
abstract: The acanthocephalan Echinorhynchus salmonis Müller, 1784 is a common parasite of salmonid fish, but it has rarely been reported from an intermediate host. Samples of benthic amphipods, Monoporeia affinis (Lindström), were taken from multiple, deep sites (usually below 70 m) in the Gulf of Bothnia over the course of more than a decade and examined for acanthocephalans. Overall, only 0.44% of 23 296 amphipods were infected, all with just a single worm. This prevalence is consistent with several previous reports of acanthocephalans in deep-water, benthic amphipods, but it appears low compared to that often reported for acanthocephalan species infecting littoral amphipods. Parasite occurrence did not exhibit a clear regional pattern (i.e. northern vs southern sites) nor did it have any relationship with site depth. At sites sampled over multiple years, parasite abundance was consistently low (mostly < 0.01), though two spikes in abundance (over 0.06) were also observed, indicating that infection can be substantially higher at particular times or in particular places. The median density of E. salmonis in samples containing the parasite was estimated as 8.4 cystacanths per m(2).
authors.affiliation: Department of Biological and Environmental Science, University of Jyvaskyla, Finland.|Marine Science Institute, University of California, Santa Barbara, CA, USA.
authors.forename: Daniel P
authors.initials: DP
authors.lastname: Benesh
authors.affiliation: Department of Biological and Environmental Science, University of Jyvaskyla, Finland;
authors.forename: Raija-Liisa
authors.initials: RL
authors.lastname: Aura
authors.affiliation: Kappelisatamantie, Hanko Pohjoinen, Finland.
authors.forename: Ann-Britt
authors.initials: AB
authors.lastname: Andersin
authors.affiliation: Department of Biological and Environmental Science, University of Jyvaskyla, Finland;
authors.forename: E
authors.initials: E
authors.lastname: Tellervo Valtonen
keywords: Acanthocephala; Echinorhynchidae; Echinorhynchus gadi; Gulf of Bothnia; aggregation; cystacanth; density; intermediate host; repeatability