Is apparent low productivity of the invasive marine mollusc Crepidula fornicata Linnaeus, 1758 related to biased age determination?
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EN
Article de revue
Ce document a été publié dans
Aquatic Invasions. 2017-01-01, vol. 12, n° 4, p. 459-468
Résumé en anglais
The slipper limpet Crepidula fornicata Linnaeus, 1758 is a major exotic invader of East North Atlantic coasts. Individuals live on
top of each other and form stacks with the youngest on the top. Earlier studies reported ...Lire la suite >
The slipper limpet Crepidula fornicata Linnaeus, 1758 is a major exotic invader of East North Atlantic coasts. Individuals live on
top of each other and form stacks with the youngest on the top. Earlier studies reported that one individual typically settles per
year. If true, it is a simplified means to provide a “shell length-age” relationship for population dynamics studies, especially
Production/Biomass ratio (P/B) assessment. However, estimated P/B ranges between 0.15 and 0.45 yr-1 seem low compared to
those of closely-related marine invertebrates and considering the invasiveness of C. fornicata in coastal habitats. In this study, we
placed artificial substrates (“tiles”) for one year in the middle of a C. fornicata colony and measured settlement. We sometimes
observed more than one individual settling per stack in a year: 4% of stacks were composed by 3 individuals, 27% by 2 individuals
and 69% were single specimen. On this basis, we formulated a model to better link the position of each C. fornicata within a stack
to its age. In addition, the C. fornicata population was annually sampled for 5 years. Then, population dynamics parameters, density
at recruitment, mortality rate, growth performance, production and P/B were estimated. We compared two cases: (i) individual age
was defined by its position in stacks; (ii) individual age was corrected by the model. Recalculation moderately increased growth
performance expectation (+2 to 8% per year) but greatly enhanced production and P/B (ca. 1.2 to 2.6-fold per year). Recalculated
P/B values ranged from 0.55 to 0.72 yr-1. While still low, they were more consistent with published values for similar large marine
invertebrates, in particular for invasive species.< Réduire
Mots clés en anglais
Mollusc
population dynamics
production
non-indigenous species