APPLIED ISSUES Replacement of the native crayfish Astacus astacus by the introduced species Pacifastacus leniusculus in a Swedish lake: possible causes and mechanisms
1995; Wiley; Volume: 33; Issue: 2 Linguagem: Inglês
10.1111/j.1365-2427.1995.tb01168.x
ISSN1365-2427
Autores Tópico(s)Marine Biology and Ecology Research
ResumoSUMMARY 1. The introduced North American crayfish Pacifastacits leniusculus is currently replacing the native crayfish Astacus astacus in a Swedish lake. Using field data from co‐occurring populations on life‐history traits and population size structure of the two species, this study evaluated possible mechanisms behind the replacement. 2. Pacifastacus showed a higher capacity for population increase; the species had a higher individual growth rate, reached sexual maturity at a smaller size and lower age, and had a higher per capita egg production than Astacus . 3. A higher frequency of non‐lethal injuries in Astacus suggested the predominance of Pacifastacus in interference interactions. These results support a competitive exclusion hypothesis. 4. A dramatic change in relative abundance of the two species in recent years was the result of an almost complete cessation in recruitment of young‐of‐the‐year (YOY) in Astacus . Poor recruitment in Astacus was probably caused by the combined effects of interspecific competition and predation, resulting in increased mortality among YOY Astacus , and by reproductive interference, suppressing the less common species. 5. The results support the hypothesis that the observed replacement of Astacus by Pacifastacus is governed by a combination of several interacting mechanisms, of which
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