title: Loss of reproductive output caused by an invasive species.
abstract: We investigated whether Neogobius melanostomus, an invader of biodiversity 'hot-spots' in the Laurentian Great Lakes region, facilitates or inhibits unionid mussel recruitment by serving as a host or sink for their parasitic larvae (glochidia). Infestation and metamorphosis rates of four mussel species with at-risk (conservation) status (Epioblasma torulosa rangiana, Epioblasma triquetra, Lampsilis fasciola and Villosa iris) and one common species (Actinonaias ligamentina) on N. melanostomus were compared with rates on known primary and marginal hosts in the laboratory. All species successfully infested N. melanostomus, but only E. triquetra, V. iris and A. ligamentina successfully metamorphosed into juveniles, albeit at very low rates well below those seen on even the marginal hosts. Neogobius melanostomus collected from areas of unionid occurrence in the Grand and Sydenham rivers (Ontario, Canada) exhibited glochidial infection rates of 39.4% and 5.1%, respectively, with up to 30 glochidia representing as many as six unionid species per fish. A mathematical model suggests that N. melanostomus serve more as a sink for glochidia than as a host for unionids, thereby limiting recruitment success. This represents a novel method by which an invasive species affects a native species.
authors.affiliation: Department of Integrative Biology , University of Guelph , Guelph, Ontario , Canada N1G 2W1.
authors.forename: Maude E M
authors.initials: ME
authors.lastname: Tremblay
authors.affiliation: Great Lakes Laboratory for Fisheries and Aquatic Sciences , Fisheries and Oceans Canada , 867 Lakeshore Road, Burlington , Ontario, Canada L7S 1A1.
authors.forename: Todd J
authors.initials: TJ
authors.lastname: Morris
authors.affiliation: Department of Integrative Biology , University of Guelph , Guelph, Ontario , Canada N1G 2W1.
authors.forename: Josef D
authors.initials: JD
authors.lastname: Ackerman
keywords: Great Lakes; Neogobius melanostomus; species at risk; unionid mussels