Size-dependent impacts of the endangered white-clawed crayfish (Austropotamobius pallipes) (Lereboullet) on the littoral community

Abstract

Key-words:crayfish, mesocosm, ontogenic diet-shift, Austropotamobius pallipes, conservationThe demise of Britain's only native crayfish (Austropotamobius pallipes (Lereboullet)) has prompted conservation-led translocations to safe isolated stillwaters (Ark sites). Many translocations represent introductions rather than re-stocking; hence it is important to ensure that there will not be a detrimental impact on communities already present. Current knowledge is insufficient to predict likely effects, although gut contents analyses suggest that A. pallipes is omnivorous and exhibits ontogenic diet shifts. A mesocosm study was conducted with the aim to first, determine community impacts of introducing A. pallipes on the benthic invertebrate community, and second investigate if impacts vary with crayfish life-stage. All crayfish life-stages strongly reduced shredder and grazer abundance, particularly thin-shelled Lymnaea snails. The small snail Physa fontinalis was preferentially consumed by juveniles, perhaps reflecting different preyhandling ability. Adults showed greater reliance on terrestrially derived detritus compared to juveniles. There were limited effects on other trophic levels, although by reducing shredders that process basal resources, crayfish impacts may be felt through the community in the long-term. RÉSUMÉImpacts dépendant de la taille de l'écrevisse à pattes blanches (Austropotamobius pallipes) (Lereboullet) sur la communauté littorale Mots-clés :écrevisse, mésocosmes, changement ontogénique de régime, Austropotamobius pallipes, conservation L'effondrement en Grande-Bretagne de la seule espèce indigène d'écrevisse Austropotamobius pallipes (Lereboullet) a incité les transferts à but de conservation dans des milieux aquatiques isolés et sûrs (sites Ark). De nombreuses translocations représentent des introductions plutôt que la reconstitution de stocks, et il est important de s'assurer qu'il n'y aura pas un impact négatif sur les communautés déjà présentes. Les connaissances actuelles sont insuffisantes pour prévoir les effets probables, bien que les analyses des contenus stomacaux suggèrent que A. pallipes est omnivore et présente des changements ontogéniques de régime. Une étude en mésocosmes a été menée dans le but d'abord, de déterminer les impacts de l'introduction d'A. pallipes sur la communauté d'invertébrés benthiques, puis d'étudier si les effets varient en fonction du stade de vie des écrevisses. Tous les stades de vie de l'écrevisse ont fortement réduit l'abondance des déchique-teurs et des brouteurs, en particulier les escargots Lymnaea à coquilles minces. Le petit escargot Physa fontinalis a été préférentiellement consommé par les jeunes,

Multi‐faceted impacts of native and invasive alien decapod species on freshwater biodiversity and ecosystem functioning

“…The negligible impacts on Shannon diversity in response to both native and invasive alien decapods are in accord with Rosewarne et al. (, ). However, the study contrasts to the significant reduction of taxonomic richness in mesocosms with P. leniusculus observed by Jackson et al.…”

“…Meta-analyses have found invasive decapods tend to exert stronger effects on lower resources such as detritus and prey compared to native species (James, Slater, Vaughan, Young, & Cable, 2015;Twardochleb et al, 2013). Native decapod species also exert strong top-down impacts, with implications for both extinctions and conservation translocations (James et al, 2015;Rosewarne, Mortimer, & Dunn, 2013). Some experiments have, however, shown non-redundant impacts of various species of invasive crayfish on invertebrates and ecosystem processes (Dunoyer et al, 2014;Jackson et al, 2014).…”

Comparing the effects of introduced signal crayfish and native noble crayfish on the littoral invertebrate assemblages of boreal lakes

“…Our results also show that equal caution should be exercised when considering the domestic introductions of native noble crayfish into lakes currently without crayfish, either with the purpose of creating "Ark sites" (Reynolds and Souty-Grosset 2012a, Rosewarne et al 2013) for this endangered native crayfish species or for fisheries purposes. Noble crayfish had effects on macroinvertebrate assemblages that were similar to the effects of signal crayfish.…”

A Lymnaea stagnalis Embryo Test for Toxicity Bioindication of Acidification and Ammonia Pollution in Water

“…Nevertheless, use of these methods in practice is still limited [45][46][47][48][49][50] Lymnaea stagnalis is a widespread species found throughout Europe, Northern Asia and North America [41]. It is noteworthy that this species can be found in still or slow-moving waters [51,52]. Features such as its common occurrence and tolerance for different types of habitats suggest that Lymnaea stagnalis is exceptionally well-suited for environmental monitoring.…”