title: Limiting similarity and the intensity of competitive effects on the mottled sculpin, Cottus bairdi, in experimental stream communities.
abstract: The identification of potential competitors has been driven by the concept of limiting similarity. Lacking are explicit tests of interaction strength among morphologically similar and dissimilar species. I used the mottled sculpin, Cottus bairdi, as a focal species in an artificial stream experiment designed to compare the effect of intraspecific competition to interspecific cometition from two very different species: a congener, the Kanawha sculpin (C. carolinae ssp.), and an unrelated species, the fantail darter (Etheostoma flabellare). The differences in morphology between these two species generate specific predictions under limiting similarity regarding the likelihood of competition and its relative strength: the congener should be a more important potential competitor. Increased fish density had a strong effect on the multivariate response of survival and growth, and on the relative condition of C. bairdi, indicating competition. The effect of additional C. bairdi or Kanawha sculpins were roughly equal, but the effect of E. flabellare was significantly greater. The most important potential impact on C. bairdi came from interspecific competition by a species that is smaller and very different in morphology, contrary to predictions based on limiting similarity.
authors.affiliation: Department of Zoology, Duke University, 2770, Durham, NC, USA.|Mountain Lake Biological Station, Route 1, Box 105a, 27708 A 24136, Pembroke, USA.
authors.forename: W J
authors.initials: WJ
authors.lastname: Resetarits
keywords: Artificial streams; Competition; Fish; Limiting similarity; Streams