Population Of White-clawed Crayfish Research Articles

Early detection of rare and elusive endangered species using environmental DNA: a case study for the Eurasian otter and the white-clawed crayfish in northwestern Italy

Monitoring, management and conservation of rare and elusive species often requires early detection of individuals, especially for re-introduced and endangered taxa. Environmental DNA (eDNA) approaches can enhance the detection power of traditional biomonitoring methods for low-density, newly-established populations. In this study, we used species-specific Real Time PCR TaqMan assays to assess the presence of two endangered freshwater species, the white-clawed crayfish Austropotamobius pallipes and the Eurasian otter Lutra lutra at eight sites in four river catchments in Liguria (northwestern Italy). The Eurasian otter was considered extinct in the study area since the 1980s. However, recent, although scattered sightings indicated a recolonisation by a few individuals. The white-clawed crayfish populations declined drastically and became increasingly dispersed in the western part of Liguria. Our eDNA analysis confirmed the presence of both species in some of the selected rivers and detected Eurasian otter DNA where the species was not recorded through traditional monitoring methods. This study confirms eDNA-based monitoring approaches as valuable tools to assess the presence of rare and elusive species and help implement protection plans at a local scale.

Cuticular Swabs and eDNA as Non-Invasive Sampling Techniques to Monitor Aphanomyces astaci in Endangered White-Clawed Crayfish (Austropotamobius pallipes Complex)

In endangered crayfish conservation projects, it is paramount to map the distribution of the causative agent of crayfish plague, Aphanomyces astaci, in native populations. Considering the inapplicability of the destructive cuticular sampling protocol for monitoring endangered populations, we explored the use of non-invasive sampling techniques to detect this pathogen with molecular assays. In the present study, we exploited environmental DNA (testing increasing water volumes combined with different filter porosities) and cuticular swabs to collect A. astaci DNA. In addition, we evaluated the impact of the storage method on DNA preservation during field activities. After the first evaluations performed on both highly infected Austropotamobius pallipes and carrier Procambarus clarkii specimens in laboratory conditions, these sampling techniques were applied to wild populations of white-clawed crayfish. Our findings highlight better results with the filtration of 5 L of water with filters of 2.7 µm porosity for eDNA analysis and demonstrate that cuticular swabbing is equally effective as the World Organisation of Animal Health’s protocol. Storage in absolute ethanol proved to be the best solution to preserve swabs and filter samples for up to a week at room temperature. In conclusion, we suggest an integration of both sampling methods when monitoring A. astaci for conservation purposes.

English

Abstract Croatian freshwaters are inhabited by four native European crayfish species. One of them is the white-clawed crayfish which is distributed in the waterbodies draining to the Adriatic Sea. This species is endangered by anthropogenic pressures on its habitats, climate change and the introduction and spread of non-native invasive crayfish species and their pathogens, with several documented declines occurring in a number of populations. Consequently, it is declared endangered and protected by international and national legislation. The aim of this study was to evaluate the efficiency of the pan-European Natura 2000 network and national protected areas in conserving the white-clawed crayfish diversity in Croatia through a GIS-based approach that overlays a map of protected areas with species distribution data, also known as a gap analysis. The analysis revealed that 66% of the white-clawed crayfish populations are covered by protected areas (including Natura 2000 sites). Results of this study are useful for the evaluation of protected areas in the conservation of this key freshwater species, and for direct future management plans.

The first record of translocated white-clawed crayfish from the Austropotamobius pallipes complex in Sardinia (Italy)

The white-clawed crayfish Austropotamobius pallipes complex is native to Europe, being present in 18 European countries, Italy included. However, the number and abundance of its populations are today restricted and it has been recently classified as “endangered” by IUCN (International Union for Conservation of Nature). Here, we report the first record of this freshwater crayfish in Sardinia Island (Italy). Using a fragment of the mitochondrial DNA 16S rRNA gene, we identified three haplotypes that correspond to the A. italicus meridionalis subclade. We provide information about the sampling area, population density and finally discuss hypotheses about the occurrence of this population in Sardinia, comparing it with other Mediterranean populations. Our results improve the existing knowledge about the phylogeography of the taxon across Italy, confirming its complex pattern of distribution. In addition to the non-native status of the Sardinian A. i. meridionalis crayfish, we showed that the most proximal Mediterranean population of white-clawed crayfish existing in Corsica belongs to A. pallipes from Southern France.

First record of an introduced population of the southern lineage of white-clawed crayfish (Austropotamobius ‘italicus’) north of the Alps

Elucidating the status of populations of endangered species of unclear origin may have important implications for conservation management. In September 2013, a population of white-clawed crayfish was discovered outside of the native range in a small artificial lake in the River Neckar catchment in southwestern Germany. White-clawed crayfish comprise two distinct lineages of yet unresolved taxonomic status, of which only the western lineage (Austropotamobius pallipes s. str.) is native to Germany. To clarify the taxonomic identity and origin of the newly discovered population, we evaluated diagnostic morphological characters and sequences of two mitochondrial genes (for 16S rRNA and cytochrome c oxidase subunit I) from two crayfish specimens. Both analyses concordantly assigned the crayfish to the southern lineage (A. ‘italicus ’), with the closest matching haplotypes originating from northwestern Italy, southeastern Switzerland, and Lake Plansee in Austria, where an abundant introduced population of this lineage is present. The artificial lake in Germany was reportedly stocked with freshwater mussels from this Austrian lake. It thus appears likely that A. ‘italicus ’ was introduced intentionally or accidentally during the process. Austropotamobius ‘italicus ’ does not naturally occur north of the Alps and thus represents a non-native taxon for Germany, a fact to be considered in its management.

Phylogeography of the white-clawed crayfish (Austropotamobius italicus) in Spain: inferences from microsatellite markers

The white-clawed crayfish (Austropotamobius italicus), a cornerstone of Spain's aquatic ecosystems, was once widely distributed throughout much of the country. Unfortunately, its populations have suffered very strong declines over the last 40years due to the spread of introduced species (red swamp and signal crayfishes), diseases, habitat loss and other anthropogenic impacts. The present work examines the genetic variation in 23 Spanish and four Italian populations of white-clawed crayfish via the analysis of microsatellite loci. The data show genetic variation in the Spanish populations to be affected by drastic and successive bottlenecks. Notwithstanding, the diversity of these Spanish populations in terms of observed heterozygosity is similar to or even higher than that recorded for other European populations studied using these same markers. North-central Spanish populations are clearly differentiated from the country's remaining populations; they should be considered distinct management units. Processes occurred in historical and recent times, such as genetic drift and translocations, contribute greatly to this genetic structure. These data provide useful information for conservation of this species, since the preservation of its population structure and genetic variability should be goals for management decisions.

Morphological diversity and phenotypic plasticity in the threatened British white‐clawed crayfish (Austropotamobius pallipes)

ABSTRACT Relocation of threatened populations is a common method employed in conservation. However, environmental differences in the new habitat may reduce the survival of relocated populations, while phenotypic plasticity may enhance the likelihood of establishment of relocated populations in their novel environment. Conservation of the British white‐clawed crayfish (Austropotamobius pallipes; IUCN Red Data List – Endangered) often involves relocation of threatened populations into isolated ponds (Ark Sites), where risk of competition with invasive crayfish is minimized. In this study, the morphology (using 12 morphometric variables) of A. pallipes in wild populations was investigated with respect to eco‐geographic variables. A field cage experiment was carried out to compare the relative survival, growth, and change in morphology of crayfish from lotic (stream) and lentic (pond) donor habitats following relocation to a lentic recipient habitat. In the wild, lentic crayfish were broader than their lotic counterparts, which may reflect an increase in branchial (gill) volume in adaptation to an oxygen‐poor benthic environment. In the relocation experiment there was no difference in the length, growth, or survival of animals from relocated lentic, lotic, or control populations. However, crayfish derived from a lotic population showed an increase in carapace width and areola width over the 4‐month growing season following relocation. This evidence for phenotypic plasticity suggests that crayfish are resilient to relocation, and that they can adapt morphologically to novel environmental conditions. Relocation of threatened populations of A. pallipes may therefore prove a useful technique in the conservation of white‐clawed crayfish populations within the UK. Copyright © 2012 John Wiley & Sons, Ltd.

Discovery of a new population of the species complex of the white-clawed crayfish, Austropotamobius pallipes/italicus (Decapoda, Astacidae) in Montenegro, range extension, endangerment, and conservation

Within the scope of a research project on decapod crustaceans in Montenegrin aquatic ecosystems, a population of white-clawed crayfish of the Austropotamobius pallipes/italicus species complex has been recorded for the first time. Based on an analysis of morphometric and genetic parameters, it has been established that Austropotamobius italicus (Faxon, 1914) and its subspecies meridionalis are distributed in Dalmatia and in the central and southern parts of the Apennine Peninsula. The new finding represents: (1) extension of the known range of the species complex A. pallipes/italicus on the Balkan Peninsula, and (2) determining the limits of the distribution and of this isolated population of that complex. The ascertained characteristics of the white-clawed crayfish’s newly discovered population in Montenegro are significant from the viewpoint of global conservation of the species in question.

Update on the distribution of freshwater crayfish in Croatia

Key-words: distribution, indigenous, non-indigenous, crayfish, Croatia Four indigenous European and two non-indigenous American freshwater crayfish species inhabit Croatian freshwater habitats. Generally, the noble crayfish (Astacus astacus), the narrow-clawed crayfish (Astacus leptodactylus) and the stone crayfish (Austropotamobius torrentium )a re distributed in the water bodies of the Black Sea drainage while the whiteclawed crayfish (Austropotamobius pallipes) inhabits rivers of the Adriatic Sea drainage. However, a few records of the noble and the stone crayfish populations in the Adriatic Sea drainage exist. Non-indigenous species the signal crayfish (Pacifastacus leniusculus) and the spiny-cheek crayfish (Orconectes limosus) are distributed in northern Croatia, in the water bodies of the Black Sea drainage. Recently, the distribution of Croatian crayfish populations has been studied more intensely within the frame of Natura 2000. In this paper we present results of field work conducted from 2005 till 2010, and compare them with previous data. Approximately 520 sites were investigated. Results indicate that non-indigenous crayfish are spreading and displacing the noble and the narrow-clawed crayfish. No mass mortalities in the contact zone have been reported. This survey also revealed the spread of the narrow-clawed crayfish westwards and southwards displacing the noble and the stone crayfishfromtheir habitats. The stone and the white-clawed crayfish populations have undergone the biggest decline in numbers. The main reasons for this are disturbance of their habitats and intensive droughts which have been pronounced of late. Collected data are helpful as a starting point for development of management strategies by state institutions dealing with protection of endangered crayfish species.

Mitochondrial DNA variability in Spanish populations ofA. italicusinferred from the analysis of a COI region

Key-words: Austropotamobius italicus, mtDNA, Cytochrome Oxidase Subunit I (COI), genetic variability, genetic structure, haplotype, conservation Austropotamobius italicus was once widely distributed throughout most of the country’s limestone basins in Spain. But its populations have shown a very strong decline over the last thirty years, due to different factors. Thus, the species now enjoys protection under regional, national and international legislation. Therefore, knowledge of the levels and patterns of distribution of genetic diversity in crayfish populations is critical when making conservation management decisions. In the present work, the current genetic structure of Spanish populations of white-clawed crayfish,A. italicus, was analyzed. Eleven Spanish populations and an Italian sample were studied through an 1184 bp-lentgh sequence of cytochrome oxidase subunit I mitochondrial gene. Data analysis revealed the existence of eight haplotypes in the Iberian Peninsula, the highest diversity reported to date in Spanish crayfish. Also a substantial genetic differentiation among populations was found, with a clear geographic pattern. The genetic variability found in these populations is similar to, and even higher, than that reported in previous studies on other Spanish and European populations of A. italicus. Thus, given the current risk status of the species across its range, this variability in certain populations offers some hope for the species from a management point of view.

Factors related to the presence of theAustropotamobius pallipes(Lereboullet, 1858) species complex in calcareous mountin rivers in central Spain

Key-words: Austropotamobius pallipes, distribution, habitat, management Alto Tajo Natural Park is a protected area in Central Spain. Mainly welldrained limestone country, this area has traditionally held abundant whiteclawed crayfish populations. Nevertheless, its occurrence has decreased during the last few decades because of different factors. To address the scarce information on the species, an extensive survey including habitat characterisation was carried out during the summer of 2008, sampling 116 water bodies. Using a combination of survey techniques, a total of 23 populations in different degrees of conservation was found. Crayfish mainly inhabited headwater stretches less than 1 km in length, together with small ponds. A significant proportion of these populations could be related to previous stocking events. The present study revealed a high degree of isolation, with populations showing a fragmented distribution pattern. The information obtained might be used to discriminate the most adequate localities for future stocking actions, hopefully improving the success of this management tool.

Spatial ecology of the white‐clawed crayfish in an upland stream and implications for the conservation of this endangered species

1. Populations of white-clawed crayfish (Austropotamobius pallipes) have undergone substantial declines across Europe. Remaining populations tend to be fragmented and in many catchments they are restricted to upland streams. Information is needed concerning their spatial ecology to assist with conservation and rehabilitation of existing fragmented populations, as well as possible reintroductions. 2. A novel method for the long-term tagging of white-clawed crayfish was used to study the spatial ecology of a white-clawed crayfish population fragment in a small, moderate-gradient upland stream. Internal passive integrated transponder (PIT) tags enabled adult crayfish (carapace length >27 mm) to be permanently tagged, each with a unique identification code and resulted in a high number of recaptures. Of 501 crayfish tagged 413 were subsequently relocated at least once. 3. Crayfish did not make extensive movements, the median annual distance moved was 84.8 m yr−1, equivalent to annual net movement of 0.233 m day−1, substantially less than reported in previous studies. The lower levels of movement may reflect the study encompassing all seasons, including winter, when crayfish are relatively inactive. 4. Significantly more crayfish moved downstream compared with upstream and distances moved downstream were significantly greater than those in an upstream direction. This may be linked to the relatively high gradient of the stream and a reduced passability of the abundant riffles to upstream movements of crayfish. 5. A small weir acted as a barrier within the stream, preventing upstream movements of crayfish. Even small barriers may limit the movements of white-clawed crayfish and have the potential to limit connectivity within populations and prevent expansion or recolonization. 6. The results presented suggest that fragmented populations of white-clawed crayfish in upland streams are unlikely to expand rapidly and reconnect to other population fragments, even where habitat is suitable. In establishing stream populations care should be taken to ensure that even small barriers to movement are removed unless these are intended to exclude non-native biota, especially crayfish. Copyright © 2007 John Wiley & Sons, Ltd.

WHITE-CLAWED CRAYFISH IN MUDDY HABITATS: MONITORING THE POPULATION IN THE RIVER IVEL, BEDFORDSHIRE, UK

White-clawed crayfish Austropotamobius pallipes are usually associated with stony substrates, tree roots, or refuges in submerged banks. The River Ivel has the last known population of white-clawed crayfish in Bedfordshire. Prior to 2005, much of the bed comprised uniform silt, plus leaf-litter. Stands of reedmace Typha latifolia and other emergent vegetation were localised in less shaded areas. Initial survey results suggested a population at low abundance. A low-cost monitoring strategy was started in 2001 and continued three times a year to 2005, using engineering bricks, which offer artificial refuges. Crayfish are counted when bricks are lifted periodically. De-silting of c. 430 m river was carried out in February 2005, to improve habitat and to maintain the flood capacity in the channel upstream of a mill weir. Additional bricks were deployed a few weeks in advance of de-silting, then bricks and crayfish were lifted prior to dredging and were returned the next day. Starting upstream, soft, wet mud was dredged out, placed on the bank and searched manually for crayfish. Banks, tree roots and shallow margins were left undisturbed. In all, 4,142 crayfish were found in dredgings from a 430 m length of the mid channel. Crayfish were strongly associated with emergent vegetation, but many were present below the surface of the silt. Crayfish released in the dredged channel immediately burrowed into the silt retained on the channel margins. Monitoring after dredging showed no change in abundance in the main area with in-bank refuges and lots of bricks, but there was an increase in occupancy of bricks in an area where most crayfish had been in emergent vegetation.

Riverine Habitat Requirements of the White–Clawed Crayfish, <i>Austropotamobius pallipes</i>

Ireland remains an important refuge for the freshwater crayfish Austropotamobius pallipes. To determine factors that influence their riverine distribution, forty rivers or tributaries of rivers that flow into Upper and Lower Lough Erne were sampled and surveyed. The nineteen sites where crayfish occurred had more bedrock and moss than those without crayfish, indicating the importance of a stable substrate and an indirect source of food. A subset of these sites, for which hydrochemical data were available, showed greater water hardness where crayfish were present, indicating that a high calcium water content is important to these animals. However, neither biological water quality nor invertebrate community structure varied between sites where crayfish were present and sites where they were absent. This indicates that biological factors have little influence on the presence of crayfish in a river and that crayfish influence biological water quality to a limited degree. M.B. Gallagher, J.T.A. Dick and R.W. Elwood (corresponding author; e-mail: r.elwood@qub.ac.uk), School of Biology and Biochemistry, Queen's University Belfast, Belfast BT9 7BL, Northern Ireland. Received 21 April 2004. Read 2 June 2005. Published 28 February 2006. INTRODUCTION The white-clawed crayfish, Austropotamobius pallipes, was previously widespread in mainland Europe, Great Britain and Ireland, but its distribution and abundance has declined in recent years due to habitat destruction, pollution (Holdich 1991) and the introduction of exotic crayfish (Holdich 1998; Holdich and Gherardi 1999). These exotics tend to be larger, and they compete for resources (Capelli and Munjal 1982; Butler and Stein 1985; S?derback 1991). American exotics are also carriers of the crayfish plague, Aphanomyces astaci, which can eliminate native populations (Capelli and Munjal 1982; Holdich 1998; Holdich and Gherardi 1999). Austropotamobius pallipes has been classified as vulnerable in the IUCN Red List (Groombridge 1993). It is also listed under Appendix III of the Bern Convention (EU/82/ 72/EEC) and Annexes II and V of the EU Habitats Directive (EU/92/43/EEC). In Ireland, however, exotic species have not been introduced and legislation bans their importation. Furthermore, although plague has been noted (Matthews and Reynolds 1990), its effect on A. pallipes was geo graphically restricted and plague is not currently a problem (Matthews and Reynolds 1992). Thus, Ireland retains healthy populations of white-clawed crayfish and has an important role to play in the conservation of this species (Reynolds 1997). Apart from legislation, conservation depends on an understanding of habitat requirements, especially if reintroductions are attempted as part of a conservation/management strategy. Within British rivers, high water quality, hard water and plentiful refugia in terms of tree roots and boulders appear to be required (Foster 1995; Smith et al. 1996; Naura and Robinson 1998). However, river studies pose a problem concerning the unit of analysis. Multiple samples taken from each river are not independent, and thus the assumptions of most statistical tests will be invalid. At the extreme, taking twenty samples from each of two rivers, one with and one without crayfish, and treating the data as independent would not be a valid approach. The present study attempts to overcome this potential problem of pseudo-replication by examining the habitat and crayfish status in the numerous rivers of a large catchment that all flow into a single lake system. Whether or not crayfish are present in specific rivers in this continuous system should depend on the habitat within each river and should be independent of their presence in other rivers. Environmental conditions (water chemistry, phys ical characteristics and invertebrate community structure) were measured at each site in order to evaluate the possibility of using these data to predict sites where crayfish should be present.

GENETIC ANALYSIS FOR CONSERVATION OF AUSTROPOTAMOBIUS ITALICUS POPULATIONS IN MARCHES REGION (CENTRAL ITALY)

The genetic characteristics of white-clawed crayfish populations in Marches Region (Central Italy) was investigated to plan conservation strategies. In order to clarify their taxonomic status, 50 specimens from ten populations were collected in six different hydrographic drainages of the Umbro-Marchigiano Appennine. The genetic relationships of the Austropotamobius italicus specimens were assessed using DNA sequences of the mitochondrial DNA 16S rRNA gene.The 3 distinct haplotypes M1, M2, M3 detected have been compared to those available in GenBank corresponding to four subspecies described for A. italicus. Our results confirmed the presence of both subspecies A. i. carsicus (M1 & M2) and A. i. meridionalis (M3) in Marches region. Two mixed populations with both subspecies have been characterized. These new data of the genetic structure of population will be used to plan management and recovery programs.

MANAGEMENT OF THE WHITE-CLAWED CRAYFISH (AUSTROPOTAMOBIUS PALLIPES) IN WESTERN FRANCE: ABIOTIC AND BIOTIC FACTORS STUDY

In France, the distribution of the white-clawed crayfish, Austropotamobius pallipes (Lereboullet, 1858), is restricted, fragmented and mainly located in headwaters. To preserve this indigenous species, it is necessary to characterize its ecological requirements (water and habitat quality). With this aim in view, a two-year study is being conducted in the Deux-Sevres department (Western France) since November 2002. Nine brooks from four different catchments are monitored regularly; eight of the nine brooks harbour white-clawed crayfish populations. Two sampling sites are surveyed per brook, the first being where the crayfish population is located and the second 2 to 3 km downstream. Physicochemical parameters (18) are measured twice monthly and biotic factors are estimated twice yearly. In this study, the I.B.G.N. (Indice Biologique Global Normalise) protocol based on the determination of macroinvertebrates was used as a biotic index of biological water quality. Results of this preliminary study on two brooks (Thouet and Verdonniere) show that physico-chemical and biological data considered separately do not provide reliable information about A. pallipes ecological requirements. However, the use of multivariate analyses (Principal Component Analysis) to combine abiotic and biotic factors highlights a good correlation between these parameters. Organic matter appears to be a better discriminating factor than mineral matter affecting presence or absence of the white-clawed crayfish.

DISTRIBUTION AND HABITAT REQUIREMENTS OF THE WHITE-CLAWED CRAYFISH, AUSTROPOTAMOBIUS PALLIPES, IN A STREAM FROM THE PAYS DE LOIRE REGION, FRANCE: AN EXPERIMENTAL AND DESCRIPTIVE STUDY

A population of white-clawed crayfish (Austropotamobius pallipes) was studied from January to October 2000 in a stream from the Pays de Loire region (Western France). An experimental modification of habitat was performed in four stream sections by providing refuges for crayfish, followed by a regular survey of population dynamics in these areas. The crayfish distribution along the brook was studied in relation to several parameters, including water quality, current speed, brook depth and presence of refuges for crayfish. Presence of hiding places was the only habitat parameter correlated with crayfish distribution along the stream whereas colonization process in modified sections was determined by sun exposure and current speed conditions. Despite a presumably high growth rate and its ability to reach locally important densities, the population appeared to be fragmented.

Distribution, population structure and conservation ofaustropotamobius pallipesin Portugal

<i>Austropotamobius pallipes<i/> has suffered a considerable reduction in range and abundance over the last two decades. The main hypotheses to explain this situation are : environmental degradation, critical climatic conditions, and the crayfish plague, though the presence of <i>Aphanomyces astaci<i/> as the aetiological agent is to be confirmed. White-clawed crayfish populations are now confined to a few small areas in the north-eastern part of the country and risk total extinction. Population characteristics are presented. Sex ratio is balanced and maximum size is small, very few individuals being larger than 75 mm. Four age-classes were identified through modal analysis. Females become sexually mature during the second year. Several conservation actions are proposed.