INTRODUCTION : THE EU-NETWORK CRAYNET- IMPACTS ON FUNDAMENTAL QUESTIONS

The European network CRAYNET “European crayfish as keystone species-linking science, management and economics with sustainable environmental quality” emphasises knowledge-based management strategies. The CRAYNET meetings concentrate on certain topics: monitoring in conservation and management of natives; interaction between natives and aliens; control of aliens; habitat restoration; reintroduction and restocking; legislation; education. The Irish meeting (Kilkenny, 2003) “The endangered native crayfish Austropotamobius pallipes: bioindicator and heritage species” initiated debates about (1) what is a bioindicator, a flagship species or a heritage species?; (2) the problem of species complexes and the need to clarify and resolve taxonomy before management; and (3) what is meant by biodiversity in the context of European crayfish? The Norwegian meeting (Halden, 2003) “European native, crayfish with a special focus on Astacus astacus: linking socioeconomics and conservation ” involved roundtables about (1) threats to indigenous population of crayfish at a landscape level; (2) exploitation, conservation, legislation; (3) reintroduction of indigenous crayfish, habitat restoration and monitoring; and (4) the urgent need for joint research about pathology. The present meeting (Innsbruck, 2004) “European native crayfish in relation to land-use and habitat deterioration with a special focus on Austropotamobius torrentim” aims to identify the species protection programs, to examine if legislation is working well in protecting vulnerable species, the state of advances about conservation genetics and how to make progress in education of the public. A permanent connection between the 12 core members provides opportunities to check the needed lines of research, to prepare recommendations, and to gather information for an atlas on the distribution of crayfish species in Europe as well as to prepare leaflets for the public

ROUNDTABLE SESSION 4A: MANAGEMENT: REINTRODUCTIONS AND RESTOCKING.

The present paper summarizes the outcome of a roundtable discussion on reintroductions or restocking as a management strategy for native European crayfish, which took place during the European Crayfish conference in Poitiers, France in September 2001. Aspects related to the suitability of the target habitat, the stocking material and the stocking procedure itself are important to consider during any reintroduction measure: Apart from general water quality and structural parameters, a suitable habitat is ideally geographically isolated from other surface waters and human activities such as intensive fishing pressure. However, it is of striking importance to make sure that the target habitat is free of crayfish plague, e.g. by experimental in situ exposure of native specimens. Overexploitation should be avoided if the stocking material originates from other surface waters and genetic aspects should be considered in stocking material originating from both natural surface waters and crayfish farms. Information for the stocking procedure itself are summarized from experiences gathered in various European countries. As an overall result of the discussion, the following three key questions related to reintroductions of native crayfish arised: 1. Why are the native crayfish not present (anymore) in the target habitat? 2. Do native crayfish survive in situ exposure as a test for crayfish plague? 3. Is the reintroduction or restocking measure successful in establishing a self-sustaining stock of native crayfish

Conserving indigenous crayfish: stock assessment and habitat requirements in the threatened Austropotamobius italicus.

International audienceAs part of the Austropotamobius pallipes species complex, the crayfish Austropotamobius italicus is a species of community interest whose preservation requires the designation of Special Areas of Conservation (SACs) (Annex II, EU Habitats Directive). This study aimed at (1) assessing the conservation status of this threatened indigenous species by stock assessment in central Italy and (2) identifying some aspects of its elective habitat

Tolerance of three European native species of crayfish to hypoxia.

Species that can act as indicators of ecosystem health offer a valuable tool in the management of natural resources. Crayfish have been suggested as bioindicators of water quality in Europe and at least one species (Austropotamobius pallipes) has been studied to determine its tolerance to pollution and its potential as a bioindicator. The genus Austropotamobius includes three crayfish species native to western Europe: A. pallipes, A. italicus and A. torrentium. It was hypothesised that because of their geographical and habitat distribution, the three Austropotamobius species might vary in their value as a bioindicator of water quality. Crayfish of species A. pallipes and A. italicus were subjected to three different treatments: hypoxia (treatment 3, approx 3 mg 1(-1) O-2), light hypoxia (treatment 2, approx 5.5 mg 1(-1) O-2) and normoxia (treatment 1, control, approx 8.5 mg 1(-1) O-2). A. torrentium crayfish were only subjected to treatment 1 (control) and 3. Variations in haemolymph sodium, calcium and chloride were used as a biomarker and concentrations were measured before and after treatment to evaluate hypoxia-induced stress. Significant differences in the concentrations of sodium between the control groups (treatment 1, normoxia) and the experimental groups (treatment 3, 3 mg 1(-1) O-2) were found in the species A. pallipes and A. torrentium. Groups of A. italicus did not show any significant difference between treatments in sodium concentrations but in chloride concentrations. Crayfish of all three species demonstrated a disruption in the ion exchange process in hypoxia, but all tolerated very low oxygen concentration for an extended period of time

Widespread Wolbachia infection in terrestrial isopods and other crustaceans

Wolbachia bacteria are obligate intracellular alpha-Proteobacteria of arthropods and nematodes. Although widespread among isopod crustaceans, they have seldom been found in non-isopod crustacean species. Here, we report Wolbachia infection in fourteen new crustacean species. Our results extend the range of Wolbachia infections in terrestrial isopods and amphipods (class Malacostraca). We report the occurrence of two different Wolbachia strains in two host species (a terrestrial isopod and an amphipod). Moreover, the discovery of Wolbachia in the goose barnacle Lepas anatifera (subclass Thecostraca) establishes Wolbachia infection in class Maxillopoda. The new bacterial strains are closely related to B-supergroup Wolbachia strains previously reported from crustacean hosts. Our results suggest that Wolbachia infection may be much more widespread in crustaceans than previously thought. The presence of related Wolbachia strains in highly divergent crustacean hosts suggests that Wolbachia endosymbionts can naturally adapt to a wide range of crustacean hosts. Given the ability of isopod Wolbachia strains to induce feminization of genetic males or cytoplasmic incompatibility, we speculate that manipulation of crustacean-borne Wolbachia bacteria might represent potential tools for controlling crustacean species of commercial interest and crustacean or insect disease vectors.This research was funded by a European Research Council Starting Grant (FP7/2007-2013 grant 260729 EndoSexDet) to RC and a Comité Mixte de Coopération Universitaire Franco-Tunisien grant to DB and FCC

A Thirty Million Year-Old Inherited Heteroplasmy

Due to essentially maternal inheritance and a bottleneck effect during early oogenesis, newly arising mitochondrial DNA (mtDNA) mutations segregate rapidly in metazoan female germlines. Consequently, heteroplasmy (i.e. the mixture of mtDNA genotypes within an organism) is generally resolved to homoplasmy within a few generations. Here, we report an exceptional transpecific heteroplasmy (predicting an alanine/valine alloacceptor tRNA change) that has been stably inherited in oniscid crustaceans for at least thirty million years. Our results suggest that this heteroplasmy is stably transmitted across generations because it occurs within mitochondria and therefore escapes the mtDNA bottleneck that usually erases heteroplasmy. Consistently, at least two oniscid species possess an atypical trimeric mitochondrial genome, which provides an adequate substrate for the emergence of a constitutive intra-mitochondrial heteroplasmy. Persistence of a mitochondrial polymorphism on such a deep evolutionary timescale suggests that balancing selection may be shaping mitochondrial sequence evolution in oniscid crustaceans