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Freshwater crayfish are amongst the largest macroinvertebrates and play a keystone role in the ecosystems they occupy. Understanding the global distribution of these animals is often hindered due to a paucity of distributional data. Additionally, non-native crayfish introductions are becoming more frequent, which can cause severe environmental and economic impacts. Management decisions related to crayfish and their habitats require accurate, up-to-date distribution data and mapping tools. Such data are currently patchily distributed with limited accessibility and are rarely up-to-date. To address these challenges, we developed a versatile e-portal to host distributional data of freshwater crayfish and their pathogens (using Aphanomyces astaci, the causative agent of the crayfish plague, as the most prominent example). Populated with expert data and operating in near real-time, World of Crayfish™ is a living, publicly available database providing worldwide distributional data sourced by experts in the field. The database offers open access to the data through specialized standard geospatial services (Web Map Service, Web Feature Service) enabling users to view, embed, and download customizable outputs for various applications. The platform is designed to support technical enhancements in the future, with the potential to eventually incorporate various additional features. This tool serves as a step forward towards a modern era of conservation planning and management of freshwater biodiversity. [ABSTRACT FROM AUTHOR]

This study investigates epibiont communities, including both protozoan and metazoan species, associated with Astacus leptodactylus in the Shiyan Dam reservoir situated in the Kermanshah province of western Iran. A total of 220 crayfish were collected for comprehensive parasitological surveys, targeting various body parts, including the gills, exoskeleton, mouth cavity, and internal organs. Protozoan species identified included Cothurnia sieboldii, Chilodonella sp., Vorticella similis, Zoothamnium sp., and Pyxicola annulata. In the metazoan category, notable species consisted of Branchiobdella kozarovi (Annelida), Philodina acuticornis (Rotatoria), Rabdochona sp. (Nematoda), and Mesocyclops strennus (Copepoda). P. acuticornis exhibited the highest prevalence among gill epibionts at 18.2%, while Chilodonella sp. showed the lowest prevalence at 0.9%. The study also revealed seasonal variations, with the highest infestation occurring in spring (82%), and the lowest in winter (24%). This research presents the first documented evidence of epibionts on A. leptodactylus in western Iran. [ABSTRACT FROM AUTHOR]

We outline a framework for evaluating scientific evidence of sentience, focusing on pain experience. It includes eight neural and cognitive-behavioural criteria, with confidence levels for each criterion reflecting the reliability and quality of the evidence. We outline the rationale for each criterion and apply our framework to a controversial sentience candidate: decapod crustaceans. We have either high or very high confidence that true crabs (infraorder Brachyura) satisfy five criteria, amounting to strong evidence of sentience. Moreover, we have high confidence that both anomuran crabs (infraorder Anomura) and astacid lobsters/crayfish (infraorder Astacidea) meet three criteria--substantial evidence of sentience. The case is, as yet, weaker for other infraorders, such as penaeid shrimps, highlighting important research gaps. Having demonstrated our framework's application to decapod crustaceans, we hope that future research will apply it to other taxa. [ABSTRACT FROM AUTHOR]

Although a large number of rivers stretches in Southeast Europe (SEE) have a pristine status compared to the rest of Europe, these ecosystems and their freshwater biodiversity are perceptibly threatened. Since crayfish species are known to cover a wide spectrum of ecological functions they are considered as keystone species and ecosystem engineers. Therefore, their decline may substantially impair local biodiversity and ecosystem services. In this manuscript we present a brief overview of the status of the native freshwater crayfish and their habitats in SEE. Different forms of physical habitat degradation as well as invasive alien crayfish species and their pathogens (e.g., Aphanomyces astaci) are simultaneously threatening endangered populations all over SEE. Even though all native crayfish species are listed in the IUCN Red List, so far none of the 33 LIFE rehabilitation projects performed in SEE, has crayfish as target species in their agenda. Furthermore, SEE countries rarely designated Natura 2000 sites for native crayfish. We propose future studies to assess the distribution and functional role of crayfish species in SEE, as well as to develop habitat suitability models for these species during future conservation projects. [ABSTRACT FROM AUTHOR]

Branchiobdella bulgariensis sp. n. is described from the River Topolnitza near the village of Dushantzi, Bulgaria. The main morphological character distinguishing the new species from Branchiobdella parasita (Braun, 1805) is the form of the spermatheca with spermathecal ampulla consisting of almost spherical proximal part and a narrower cylindrical or bulb-like distal part. In contrast, B. parasita is characterised by oval spermatheca. Another feature distinguishing these two species from one another is the form of peristomium: in B. bulgariensis, the dorsal lip of peristomium has four lobes while, in B. parasita, the peristomium is "simple, thin-skinned" (Braun, 1805) and "bears eight micro-tentacles" (Henle, 1835). The only known host of B. bulgariensis sp. n. is Austropotamobius torrentium. The new species has been found so far at several sites in Bulgaria and unknown locality in Slovakia. An unusual character for the order Branchiobdellida is described, i.e. ontogenetic development of jaws of B. bulgariensis resulting in a different shape of these structures in specimens of different age. [ABSTRACT FROM AUTHOR]

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At the territory of Bosnia and Herzegovina Austropotamobius pallipes (Lereboullet, 1858) is present mainly in the Neretva basin, partly in the Una and Tsetina river basins (Trožić-Borovac et al., 2012). This species was registered at elevations from 180 to 1024 m a. s. l., but most habitats are located at elevations from 300 to 600 m a. s. l. Based on indirect data, one can state that more than 2/3 of the crayfish population in the Neretva basin is concentrated in the Neretvica basin. Our studies showed that the crayfish are very irregularly distributed in the Neretvica basin. The crayfish are almost absent at well-flushed habitats without CPOM (deposits of coarse particulate organic matter, e. g., fallen leaves), as well as at habitats with monotonous boulders or gravel-sand bottom. The study of the size structure of the crayfish population showed the presence of juvenile crayfish with a size of less than 5 cm in the Neretvica River course. The most balanced structure of the crayfish population represented by juvenile as well as adult species is observed in Gorovnik. [ABSTRACT FROM AUTHOR]

Copyright of Natura Croatica is the property of Natura Croatica and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The pleopodal fecundity of Pontastacus leptodactylus from Hirfanlı Dam (Turkey) was investigated. Reproductive period, length at first maturity, as well as the number, weight and diameter of pleopodal eggs were determined. The study was conducted monthly at six different stations from June 2017 to May 2018. Berried females were observed between December and May. L50 length at first maturity of the female crayfish population in the lake was estimated as 9.04 cm and this value is below the applied 10 cm Minimum Landing Size (MLS). The mean egg number of the population was 240.18, the mean egg weight was 0.0122 g and the mean egg diameter was 2.702 mm. While an increase in female total length had a positive effect on mean total egg number, sampling period (progressive incubation period from December to May) caused negative effects. The mean total egg number for 1 mm total length was found to be 2.18. When the mean pleopodal egg number of the crayfish population in Hirfanlı Dam Lake was compared with populations of P. leptodactylus in other localities it was concluded that the stock is quite productive. [ABSTRACT FROM AUTHOR]

Copyright of Knowledge & Management of Aquatic Ecosystems is the property of EDP Sciences and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

As North American crayfish biodiversity becomes increasingly imperiled, the ambiguous nature of the current taxonomic framework can impede conservation efforts. The taxonomy of the family Cambaridae Hobbs, 1942 has historically been based on morphology, but recent studies using molecular phylogenetic techniques have revealed taxonomic inconsistencies, including a polyphyletic Cambarus Erichson, 1846. We took a step towards increasing the taxonomic resolution of Cambaridae by investigating a group of primary burrowing crayfishes which were historically part of the Cambarus subgenera Lacunicambarus Hobbs, 1969 and Tubericambarus Jezerinac, 1993. This group, here called the devil crayfish group (DCG) because it includes the devil crayfish (Cambarus diogenes Girard, 1852), has a confusing taxonomic history and is in need of revision to inform conservation assessments. We tested the hypothesis that the DCG is monophyletic through phylogenetic analyses of mitochondrial DNA sequence data from multiple specimens of the eight DCG species and a broad sample of taxa representing approximately 70% of the species in what is currently recognized as Cambarus. Seven of the eight species from the DCG form a well-supported, monophyletic group that is distinct from the remainder of what has traditionally been recognized as Cambarus. Our analyses place the DCG as sister to a clade consisting of taxa from Creaserinus Hobbs, 1973, Faxonius Ortmann, 1905, and Barbicambarus Hobbs, 1969. Based on our results and on unique morphological and ecological characteristics, we split seven of the eight DCG species from Cambarus and elevate the subgenus Lacunicambarus to generic level to accommodate them. We redescribe Lacunicambarus and the devil crayfish sensu stricto (Lacunicambarus diogenes comb. nov.) and designate a neotype for the species to facilitate subsequent revisionary work. [ABSTRACT FROM AUTHOR]

White-clawed crayfish Austropotamobius pallipes (Lereboullet, 1858) are one of five crayfish species indigenous to Europe, and the only crayfish species to occur in Ireland. With no known invasive species posing a risk, the Irish population is of considerable conservation importance, particularly in a European context. While there are a number of capture techniques described for crayfish population studies, many have a number of limitations associated with them. There is a need therefore to evaluate new and emerging techniques, so as to assess their efficacy for monitoring A. pallipes populations. Artificial refuge traps (ARTs), an alternative passive capture method, were evaluated against three other widely used capture techniques during the summer months of 2015. Results indicate ARTs to be an effective technique for sampling crayfish, and suggest that, in combination with other capture methods, ARTs could depict accurate population structures, and reduce some of the sampling effort and bias associated with crayfish monitoring. [ABSTRACT FROM AUTHOR]

Invasions of the rusty crayfish Orconectes rusticus (Girard, 1852) in lakes have led to the local extirpation of resident crayfishes and altered littoral communities. The spread of O. rusticus into streams poses an equally serious threat to the biodiversity of resident crayfishes and fishes. We found that O. rusticus in northern Wisconsin streams were significantly smaller than O. rusticus from lakes (P < 0.001) and not significantly different than Faxonius propinquus (Girard, 1852) (P < 0.001) from lakes or streams. We tested time to reach a limited food resource, performance, in 4 water velocities, 5, 30, 50, and 66 cm sec-1, in a laboratory flume. Performance of O. rusticus and F. propinquus did not differ within water velocities, but was reduced in water velocities of 50 and 66 cm sec-1. Performance also did not differ between large and small O. rusticus within water velocity treatments but was also reduced at 50 and 66 cm sec-1. Performance of O. rusticus and F. propinquus from lakes, however, was significantly lower than that of O. rusticus from streams (P < 0.05). In all experiments, performance of crayfish in the 66 cm sec-1 treatment was below 50%, suggesting that this is a critical water velocity for O. rusticus and F. propinquus. Our results also suggest that stream segments with high velocities may reduce upstream dispersal rates of O. rusticus from lakes thus potentially reducing the spread to upstream lake ecosystems. [ABSTRACT FROM AUTHOR]

Copyright of Knowledge & Management of Aquatic Ecosystems is the property of EDP Sciences and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Biological invasions are a key threat to freshwater biodiversity, and identifying determinants of invasion success is a global conservation priority. The establishment of introduced species is predicted to be hindered by pre-existing, functionally similar invasive species. Over a five-year period we, however, find that in the River Lee (UK), recently introduced non-native virile crayfish (Orconectes virilis) increased in range and abundance, despite the presence of established alien signal crayfish (Pacifastacus leniusculus). In regions of sympatry, virile crayfish had a detrimental effect on signal crayfish abundance but not vice versa. Competition experiments revealed that virile crayfish were more aggressive than signal crayfish and outcompeted them for shelter. Together, these results provide early evidence for the potential over-invasion of signal crayfish by competitively dominant virile crayfish. Based on our results and the limited distribution of virile crayfish in Europe, we recommend that efforts to contain them within the Lee catchment be implemented immediately. [ABSTRACT FROM AUTHOR]

Patterns of diversity and faunal turnover of major groups of decapod crustaceans throughout the Phanerozoic are analyzed based upon data from all known fossil species reported to date. Age, range, and habitat preference data were compiled for 3637 species arrayed in 1035 genera and 173 families. Grouped at the infraordinal level, Anomura, Gebiidea, and Axiidea consistently occupied specific, preferred environments throughout their geologic history. Achelata are known from a variety of siliciclastic environments until the Holocene when they are found in coral and other carbonate environments. Habitat preferences of dendrobranch and pleocyemate shrimp, with a low preservation potential, are difficult to evaluate because they are found almost exclusively in low energy siliciclastics and lithographic limestones, whose mode of origin is not clear. Clawed lobsters, the so-called podotreme or primitive crabs, and heterotreme crabs have historically occupied a wide range of habitats. However, the temporal pattern of diversity of these groups is one of faunal turnover on a scale of tens of millions of years. Clawed lobsters were the first of these groups to be most diverse, followed in the Late Jurassic and Cretaceous by the podotreme or primitive crabs. Heterotreme crabs appeared in the Early Cretaceous and dominate numerically in the Cenozoic. These patterns of habitat preference of broad groups of decapods suggest that the limits of distribution are controlled by the Bauplan of each group rather than by extrinsic factors. [ABSTRACT FROM AUTHOR]

Seasonality in the immune defence of invertebrates can coincide with environmental variation but whether it is endogenously regulated, via biological clocks, or affected by previous immune challenges remains unclear. Using the native noble crayfish (Astacus astacus) held under constant laboratory conditions for a year, we explored (1) potential endogenous seasonal variation in immune defence, i.e. the encapsulation response, (2) the potential positive effect of repeated challenges with a standardized immune insult in subsequent seasons, i.e. long-lasting immune priming, and (3) whether long-lasting immune priming is dependent on endogenous seasonality. Independent measurements of the encapsulation response in different seasons revealed significant variation and a decrease in autumn. This result indicates previously undetected endogenous seasonal variation in invertebrate immunity. The weaker immune defence observed in autumn, i.e. the reproductive season of crayfish, might be caused by a circannual clock. When corrected for endogenous seasonality, we found no evidence for long-lasting immune priming. [ABSTRACT FROM AUTHOR]

The aim of this study was to evaluate the effects of practical diets with different levels of vitamin A on survival and growth of juvenile crayfish ( Pacifastacus leniusculus). An 80-day trial was conducted with stage 2 juveniles from the onset of exogenous feeding. Four diets differing in the level of retinyl acetate were tested: 0, 0.0025, 0.0050 or 0.0100 g kg−1 diet, equivalent to 0, 2500, 5000 or 10 000 IU vitamin A kg−1 diet, respectively. Each diet was tested on grouped or individually isolated crayfish. Crayfish fed the diet with 5000 or 10 000 IU vitamin A kg−1 diet achieved the highest survival (average of grouped and isolated: 88.9%) and growth (grouped and isolated: 13.45 mm carapace length, 533.4 mg weight). Final growth of isolated crayfish was significantly higher than that of grouped crayfish for all diets. This study provides the first data on vitamin A requirements of freshwater crayfish. A level of 5000 IU vitamin A kg−1 can be recommended for juvenile P. leniusculus during the first period of intensive rearing. [ABSTRACT FROM AUTHOR]

The rusty crayfish, Orconectes rusticus (Girard, 1852), is native to the Ohio River basin, but was introduced into northern Midwestern lakes through the bait trade about 50 years ago. Since then, the rusty crayfish has spread rapidly through lakes in northern Wisconsin, displacing two resident species of crayfish, O. propinquus (Girard, 1852), the northern clearwater crayfish, and O. virilis (Hagen, 1870), the virile crayfish. Previous studies have shown that as O. rusticus invades, it hybridizes extensively with O. propinquus, but not with O. virilis. Here, we examine why stable hybrid zones do not form between O. rusticus and O. propinquus, but instead hybridization accelerates the decline of O. propinquus. We report that although putative F1 hybrids tend to grow faster and survive better than other crayfish, backcross hybrid crayfish tend to have fewer young (at a given age) that grow more slowly and experience lower survivorship than F1 hybrids and both parental species. Parental O. rusticus, in comparison, have offspring numbers and growth rates more similar to those of F1 hybrids, while survivorship is intermediate between F1 hybrids and backcrosses. Consequently, hybrid breakdown appears to occur in latter generation crayfish of mixed ancestry, resulting in unstable hybrid zones in lakes that speed the extirpation of O. propinquus. Our findings underscore the negative effects that hybridization can have on conserving native gene pools, a danger that may be particularly detrimental for the great diversity of North American crayfishes. [ABSTRACT FROM AUTHOR]

The aim of this study was to evaluate different replacement levels of fishmeal ( FM) by feather meal (FeM) on survival and growth of juvenile crayfish ( Pacifastacus leniusculus). An 80-day experiment was conducted with stage 2 juveniles from the onset of exogenous feeding. Four practical diets (500 g kg−1 protein) differing in the level of replacement of FM protein by FeM protein were prepared: 0% (control diet), 15% (8.2% dietary FeM), 25% (13.7% dietary FeM) or 35% (19.2% dietary FeM). Each diet was tested on grouped or individually isolated crayfish. Crayfish fed the control diet or 15% replacement achieved the highest survival (average of grouped and isolated: 88.2%) and growth (grouped and isolated: 13.58 mm carapace length, 523.2 mg weight) and the lowest feed conversion ratio (average of grouped and isolated: 1.11). Final growth of isolated crayfish was significantly higher than that of grouped crayfish for all diets. This study provides the first data on the substitution possibilities of FM by FeM in diets for freshwater crayfish. An 8.2% of FeM (15% replacement of FM protein) can be included in extruded diets for juvenile P. leniusculus during the first 80 days of intensive rearing without impairing growth or feed conversion. [ABSTRACT FROM AUTHOR]

We describe an intersex specimen of the Marmorkrebs, the oniy obligate parthenogenetic freshwater crayfish with an all-female population. The individual was a fully functional female which possessed male-like first pleopods. Nevertheless, it reproduced successfully and the offspring were normally developed parthenogenetic females, lacking any trace of male traits. The general rarity of aberrant sexual traits in freshwater crayfishes, in particular in Procambarus, is discussed. We suggest that a dysfunction of the sex determining system, which controls the anlagen of the androgenic glands during development, caused the partial male-like phenotype of this Marmorkrebs specimen. The application of this organism for investigations of sex determination and differentiation is recommended. [ABSTRACT FROM AUTHOR]

Branchiobdellidans or crayfish worms are clitellate annelids and ectosymbionts of freshwater crayfish. An investigation of branchiobdellidan infestation was undertaken in a population of endangered white-clawed crayfish (Austropotamobius pallipes) in the river Aire, UK. Thirty two percent of animals were infested either by the adult parasite or their cocoons (n=107). Parasite burden increased with host size, but did not differ with sex. Observations of crayfish gill tissue revealed a strong positive relationship between melanization of filaments and parasite prevalence and burden. Taxonomic identification revealed that 1 species of branchiobdellidan was present, Branchiobdella astaci. The first sequences were generated for this species and phylogenetically analysed alongside published sequences for 5 other branchiobdellidan species in Europe. The position of B. astaci within the genus Branchiobdella was confirmed, and it was found to cluster as a sister group to B. parasita. [ABSTRACT FROM AUTHOR]

Austropotamobius pallipes is a vulnerable crayfish, and therefore it is necessary to analyse reproduction in the extant populations. Details of the female annual reproductive cycle in a Mediterranean population are provided for two consecutive years. Maternal-size-related variables and date of collection have been considered in relation to the number of ovarian and pleopodal eggs. Reproductive data from 2587 females collected by hand and traps are reported. In total, 204 (14.69%) and 231 (15.93%) individuals in 2003 and 2004, respectively, were ovigerous. Demonstrable differences exist between ovarian and pleopodal egg counts. In particular, ovarian egg counts were considerably higher than expected pleopodal egg numbers. Mating begins in November and is followed by egg laying in early December-January. Berried females occur until May-June, when hatching occurs. The numbers of both ovarian and pleopodal eggs are correlated with the size of females, although fecundity slightly decreases in larger females. The histology of the reproductive organs of both sexes is also analysed. [ABSTRACT FROM AUTHOR]

In present paper the results from a study on the Stone crayfish in the Dospat Dam were represented. During the study period a total of 551 stone crayfish were caught (328 males and 223 females) by traps. The size-weight characteristics of the population were established, as well as the determination of its relative density (CPUE), and the ratio between the males and the females. [ABSTRACT FROM AUTHOR]

A key for the 3 crayfish species of the family Astacidae (Crustacea, Decapoda) found in Bulgaria: Astacus leptodactylus Eschscholtz, 1823; Astacus astacus (Linnaeus, 1758) and Austropotamobius torrentium (Schrank, 1803) is presented. More important identification characters are illustrated with original photographs. [ABSTRACT FROM AUTHOR]

The present study was carried out to evaluate the effects of selectivity of fyke-nets of different mesh size on Astacus leptodactylus (Eschscholtz, 1823), in lake Eğirdir in Turkey. Crayfish were sampled monthly using fyke-nets of 26 mm (control), 34 mm (traditional), and 42 mm (increased) mesh size from July to December 2007. Differences in the mean size, weight, and number of crayfish caught with each mesh size were determined. The average length and weight were found to increase proportionally to mesh size. The highest mean weight (g) (± SD) (41.07 ± 4.61) was achieved at 42 mm mesh size compared with mean weights of 32.76 ± 4.53 and 29.29 ± 4.37 at sizes of 34 and 26 mm, respectively. The same trend was observed in mean TL of crayfish caught at 42, 34, and 26 mm size, but no significant difference was detected in mean length and weight for male and female crayfish. The weight of crayfish caught in 42 mm mesh was 8.3% higher than that in 34 mm mesh size. The lowest number of crayfish was caught with the 42 mm mesh size, while the highest number was captured with 34 mm mesh. This study shows that increasing mesh size has a positive effect on selectivity, because the mean total length L50 in the catch approximates the minimum landing size for this species in Turkey. L50 values (total length) for female, male, and combined sexes were 9.93 ± 0.41 cm, 9.73 ± 0.34, and 9.93 ± 0.34 cm for 42 mm, and 6.54 ± 0.60 cm, 7.28 ± 0.30, and 7.09 ± 0.3 cm for 34 mm, respectively. It was presumed that 34 mm mesh size, which is commercially used, has poor selectivity. On the other hand, 34 mm mesh size caused a loss in marketable crayfish among the three tested mesh sizes. The 42 mm mesh size provided the most appropriate selection of the crayfish, compared with sizes of crayfish at 34, and 26 mm mesh, respectively. Meanwhile, as mesh size increases, the female escape ratio becomes higher than the male escape ratio. Thus, increase in mesh size of nets will have a positive impact not only on preserving a sustainable stock, but also sparing labour and time to be spent on fishing operations. [ABSTRACT FROM AUTHOR]

Recent advances in intensive rearing of astacid juvenile crayfish have greatly improved the results. This challenges the current application possibilities of the studies performed previously, and new research on density is required. A 100-day experiment was carried out under controlled conditions to evaluate density effects on survival and growth rates of juvenile crayfish in optimal conditions of feeding. Juvenile stage 2 Pacifastacus leniusculus were stocked in fibreglass tanks (1 m2, 200 l water) at 20 ± 1°C and fed a dry diet for salmonids supplemented with restricted amounts of Artemia nauplii. Stocking densities were 100, 300, 600 and 1,000 crayfish m−2. Mean survival rate was reduced significantly with increased stocking density, ranging from 86.33% (100 m−2) to 39.13% (1,000 m−2). All checks showed that at the lowest initial density (100 m−2) animals grew significantly faster those at higher densities, recording a final carapace length of 15.28 mm and weight of 1.08 g. Among the treatments of 300, 600 and 1,000 m−2 no differences were found either in carapace length or in weight throughout the experimental period, with a final mean growth of 14 mm carapace length and 0.72 g weight. The final proportion of animals with chelae autotomy rose significantly with increasing stocking density, ranging from 14.44% (100 m−2) to 41.45% (1,000 m−2). This study shows that diet is a decisive factor for stocking successfully high densities under controlled conditions and provides useful information to set adequate densities in accordance with the production objectives. [ABSTRACT FROM AUTHOR]

The acocil C. montezumae is a freshwater crayfish endemic to the Central Plateau of Mexico, but, in recent years, the natural population of this species has diminished considerably. In this work was investigated growth performance and feeding of this crayfish reared at high densities. A random block experimental design with two repetitions and three treatments (77, 154 and 231 crayfish/m2) was carried out. Organisms were fed every third day with 15% of their total biomass of shrimp commercial food with 25% of crude protein, and individual food consumption (IFC) was calculated. Significant differences (ANOVA, P < 0.05) were detected in final weight, absolute increase, relative rate of increase, instantaneous rate of increase, yield and survival rate between the densities, with those reared at a density of 77 organisms/m2 reaching the largest sizes. There were no-significant differences (P > 0.05) among treatments in terms of initial weight, specific growth rate and feed conversion l rate. [ABSTRACT FROM AUTHOR]

Theoretical models of animal assessment and decision strategies have assumed animals possess accurate information about themselves. The imperfect nature of self-assessment could cause animals to make inaccurate decisions during agonistic encounters. By manipulating sensory information used in self-assessment in crayfish, Orconectes rusticus, it may be possible to alter either decision-making paradigms or outcomes associated with agonistic encounters. We examined the role of self-assessment in the agonistic behaviour of crayfish by using differing shelter sizes to alter self-assessment of size. Similar-sized crayfish were kept in tanks with small, medium, and large shelters (relative to body size) and subsequently were fought against size-matched, naive opponents in novel chambers to remove resource value as a variable. Crayfish in small shelter treatments initiated and won more fights than crayfish in other shelters. Crayfish in the small shelter treatment had shorter durations of fight when compared to crayfish with the medium and large shelters. These results are consistent with the concept that crayfish placed in smaller shelters may be self-assessing their physical size and, thus, their fighting ability, higher than crayfish in larger shelters. Based on these results, current theoretical models need to include the role of inaccurate self-assessments in agonistic decision making paradigms. [ABSTRACT FROM AUTHOR]

The presence of two male morphs in crayfishes of the family Cambaridae is well established, but the selective value of this trait is unknown. Measurements of growth following molts to Form I and Form II were used to examine the hypothesis that alternating between the two molts may serve as an adaptation allowing animals to efficiently increase overall body size. The results revealed that the change in carapace length was significantly greater in animals molting to Form II, whereas changes in chela length and width were significantly greater in animals molting to Form I. These differences allow animals to maximally increase body length when molting to Form II and maximally increase chela size when molting to Form I. [ABSTRACT FROM AUTHOR]

1. Species invasions are a leading threat to native species and ecosystems. How populations of native species respond to the presence of invasive species will ultimately determine their long-term persistence. 2. In this study, we capitalise on a unique opportunity to compare the behaviour and growth of naïve and experienced virile crayfish ( Orconectes virilis Hagen) populations in the presence of invasive rusty crayfish ( O. rusticus Girard ). In behavioural trials, experienced O. virilis (coexisted with O. rusticus for >30 years) showed more aggressive behaviour than their naïve counterparts. Naïve O. virilis retreated from aggressive interactions with O. rusticus 38% more often than experienced O. virilis. Experienced O. virilis spent 39% more time occupying shelter than naïve O. virilis. 3. There were also differences in O. rusticus behaviour: O. rusticus spent 24% more time occupying shelter with naïve O. virilis relative to experienced O. virilis. 4. In field mesocosm experiments with O. rusticus, naïve O. virilis declined in body mass by 1% while experienced O. virilis’ body mass increased by 6%, thus highlighting the potential population-level implications of the previously observed behavioural effects. 5. Our work demonstrates significant behaviour and growth differences between naïve and experienced O. virilis in the presence of invasive O. rusticus. Whether this difference is the result of phenotypic plasticity or evolution by natural selection remains to be determined. Either way, this area of inquiry has implications for managing native populations and species in an increasingly invaded world. [ABSTRACT FROM AUTHOR]

In the mouthparts of the crayfish, we find the flagellar exopods of the symmetrical 1st, 2nd, and 3rd maxillipeds, which do not participate in food processing but occasionally generate water currents by their repetitive beating. Earlier, we have observed and filmed the flagellar movements in freely behaving Procambarus cubensis reared in the laboratory, and suggested that these movements were an overt expression of the excited state of the crayfish. Recently, we used a high-speed scan camera (100-240 fps) to observe and document the flagellar movements in the tethered crayfish. Beating of all six flagella occurs with the same frequency (8.3-8.4 Hz). There is, however, an obvious phase shift between various ipsilateral and bilaterally symmetrical flagella. All right and left flagella can beat simultaneously, or only one side can be active. Each flagellum can stop for a short time, which, however, has no influence on the beating of the other flagella. Flagellar movements seen in slowly displayed video-movies are complex and variable in their trajectories, and each flagellum is moving in its own manner. It is suggested that each flagellum has its own central pattern generator, and that activation of all ipsilateral flagella concurrently is established by common higher commands. [ABSTRACT FROM AUTHOR]

The differentiation of the female reproductive system from a macroscopic and microscopic point of view was studied in Cherax quadricarinatus. For this characterization, 184 females were dissected and processed for the histological analysis. From the differentiation of the ovary up to its maturity, three ovarian morphotypes could be distinguished macroscopically: parallel strands without any contact between them, an H-shaped ovary, and a Y-shaped ovary. These morphotypes were compared within the Astacida. Four ovarian developmental stages were recognized based on ovary color, and the histological structure and relative proportion of cellular types. The post-spawning ovary was also characterized. The components of the female reproductive system sheath were described and its modifications in the ovary and oviducts were determined and compared. Theoretical aspects of the study of sexual differentiation in C. quadricarinatus were discussed within a phylogenetic framework. [ABSTRACT FROM AUTHOR]

A new crayfish, Orconectes (Gremicambarus) quinebaugensis, is described from southern New England. This species is similar in morphology to its sister species, O. (G.) virilis (Hagen), which also occurs in New England. Orconectes quinebaugensis is found in small streams with rocky or gravel substrate, with or without O. virilis or other crayfish species. Orconectes quinebaugensis differs from other members of the O. virilis species complex in the morphology of the first pleopods of adult males; in O. quinebaugensis, both rami of the first pleopod are clearly and equally recurved, and the central projection comprises 30.2-34.0% of the total length of the pleopod. In addition, it can be distinguished from all known members of the complex by the shape of the dactyl of the chelipeds. [ABSTRACT FROM AUTHOR]

Asymmetry in traits of sexual relevance may impair copulation behaviour and sexual performance of males, ultimately resulting in a fitness cost. Freshwater crayfish males use chelae, a sexually selected trait, to secure and position the female prior to and during mating. Thus, a relatively large chelae asymmetry, resulting from accidental loss and regeneration of one cheliped after autotomy, could have great consequences for male sexual behaviour. We studied copulatory behaviour and sperm expenditure of males paired to a mated female in Austropotamobius italicus, a freshwater crayfish species where both male and female mate multiply and where last-mating males are able to actively remove previously deposited sperm. We aimed at assessing whether male sperm removal and expenditure varied according to sperm allocated by first-mating males, and according to copulation behaviour and phenotypic traits (carapace length, chelae length and relative chelae asymmetry) of second-mating males. Second-mating males did not adjust their ejaculate size in relation to first-mating male ejaculate, nor to the first-mating male’s sperm removed. Moreover, the amount of sperm removed by second-mating males increased with increasing first-mating males ejaculate size, and first-mating male sperm remaining after removal did not correlate with the original first-mating male ejaculate size. Interestingly, the amount of sperm removed by second-mating males decreased with increasing relative chelae asymmetry, while increasing with male body size. However, second-mating (but not first-mating) asymmetric-clawed males produced larger ejaculates than symmetric-clawed ones. Importantly, the proportion of second-mating male sperm remaining after the two matings did not vary with relative chelae asymmetry nor with body size of second-mating males. Thus, small, asymmetric-clawed crayfish males appear to adopt sperm allocation tactics that allow them to fully compensate for their inferior sperm removal ability. [ABSTRACT FROM AUTHOR]

A new species of crayfish, Orconectes taylori, is described from tributaries of the North Fork Obion River in western Tennessee (common name: Crescent Crayfish). It occurs in small to medium size sandy bottom streams, and is found in leaf litter and woody debris along the banks. It belongs to the subgenus Trisellescens Bouchard & Bouchard, 1995 and can be distinguished from other species in the group by a combination of the length and curvature of the central projection of the form I gonopod, carina on the rostrum, appressed tubercles on the margin of the palm of the chela, and width of the areola. In the course of this study, a new drainage record was obtained for Orconectes pagei Taylor & Sabaj, 1997 formerly thought to occur only in tributaries of the Tennessee River in western Tennessee [ABSTRACT FROM AUTHOR]

Procambarus pentastylus, a new crayfish of the subgenus Pennides, is described from the Calcasieu River drainage of southwestern Louisiana. The species formerly was confused with Procambarus dupratzi Penn, 1953 but differs in several details of the form I male pleopod, including shorter terminal elements and the presence of a large adventitious process (here termed the pentastyle) mesial to the central projection. Procambarus dupratzi as here restricted is known only from the Sabine, Neches, and Trinity River drainages in Louisiana and Texas. A key to form I males of Pennides species known from west of the Mississippi River is presented. [ABSTRACT FROM AUTHOR]

Baited modified minnow traps are often used to collect rusty crayfish (Orconectes rusticus), an invasive species in many areas of North America. However, the use of baited traps as a collection gear for decapods has received considerable scrutiny. We designed a tank-experiment to determine if captured rusty crayfish exclude uncaptured rusty crayfish from baited traps. We found that significantly more crayfish were captured in traps where captured crayfish were immediately removed (experimental tanks) than in traps where crayfish were not immediately removed (control tanks). in addition, more small crayfish were captured in the experimental tanks. These results are consistent with a hypothesis that large and aggressive previously captured rusty crayfish exclude other, generally smaller, rusty crayfish from the trap. [ABSTRACT FROM AUTHOR]

The freshwater crayfishes are distributed across all but the Indian and Antarctic continents with centers of diversity in the southeastern Appalachian Mountains in the Northern Hemisphere and in south–east Australia in the Southern Hemisphere. There are currently over 640 described species of freshwater crayfishes with an average of 5–10 species still being described each year. Freshwater crayfishes can serve as keystone species in aquatic habitats, but a few species are also significantly invasive and can cause impressive damage to the fragile freshwater habitat. Crayfishes inhabit caves, burrows, streams, lakes and strong burrowers can even be found in terrestrial habitats where they have burrowed to the water table or where rainfall is sufficiently abundant to provide the needed moisture. The freshwater crayfishes, like the habitats in which they are encountered, are generally endangered to some degree and conservation efforts would do well to focus on them as key elements of the freshwater ecosystem. [ABSTRACT FROM AUTHOR]

Juvenile noble crayfish, Astacus astacus and spiny-cheek crayfish, Orconectes limosus were reared from the 2nd and the 3rd developmental stage (i.e. since the stage of independence), respectively, until the end of the growing season. The first period revealed very low survival rate of O. limosus in the communal stock (7 ± 6.2%), probably caused by predation of A. astacus. Separately reared O. limosus proved significantly higher survival rate (49 ± 9.2%) than those in the communal stock with A. astacus. The latter species also showed the highest survival rate in this case (90 ± 7.1%). This was not found to differ from the survival rate of separately reared noble crayfish (86 ± 3.1%). In general, both the significant effect of bigger size of A. astacus than that of O. limosus and higher intra-specific cannibalism of O. limosus were reflected during the first phase of rearing. Size and weight of both species were equivalent 11 weeks after hatching (8 weeks of rearing). The higher cumulative survival rate was reached in the intraspecific culture of A. astacus (90%) while low cumulative survival of both species was found in communal stock (less than 50%) in the second phase of rearing. At the end of the growing season, 19-week-old O. limosus attained a higher mean size and weight but were more variable in the group (29.3 ± 5.17 mm and 616.4 ± 412.53 mg) than A. astacus (21.2 ± 1.82 mm and 229.9 ± 59.45 mg). Single and communal stock did not differ. Growth of O. limosus was much faster than that of A. astacus. [ABSTRACT FROM AUTHOR]

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Olfactory cues are among the sensory inputs that crayfish use in establishing dominance hierarchies. Throughout their lives, new neurons are continuously added into brain cell clusters 9 and 10, which contain somata of olfactory local and projection interneurons, respectively. Using markers for DNA synthesis (bromodeoxyuridine) and mitosis (phospho-histone-3), we tested juvenile crayfish (Procambarus clarkii) to examine effects of pairwise social experience on proliferation and survival of cells in these brain regions. Proliferating and mitotic cells appeared within restricted neurogenic areas in both clusters and in `tails' extending from them. These tails, embedded in tubulin-positive strands, are linked by a patch of cells. Neither cell proliferation nor mitotic activity was affected by social dominance. Cell survival of neuronal precursors was affected by dominance: compared to dominants, subordinates had fewer newborn cells surviving in cluster 9 after 14 days of social experience. Social experience also affected body growth rate, but the effect of social experience on neurogenesis remained when differences in body growth rate were statistically controlled. We conclude that social domination enhances survival of new olfactory interneuronal precursors compared to social subordination but not compared to social isolation. [ABSTRACT FROM AUTHOR]

Our study examined the effect of dominance on feeding, mating behaviour, and shelter use in the crayfish, Orconectes rusticus. In three different experiments, dominance and resource use were recorded in male populations, mixed-sex populations, and when crayfish were alone. Crayfish established dominance status in populations or through status conditioning and had access to variable resources (food, mates, and/or shelters) in each experiment. Subsequent resource use was quantified and compared to dominance rank. Our results did not match conventional predictions that dominance would confer increased access to resources. Top ranked dominant crayfish occupied shelter significantly less than lower ranks. This differential shelter use may be due to dominant motivation to reinforce status, as dominants also participated in the most agonistic interactions. When dominant crayfish had access to resources in the absence of conspecifics, dominant crayfish occupied shelter significantly more than subordinate and naïve crayfish. This result illustrates that present social context has a significant impact on behavioural decisions in crayfish. Social history and social context interact to determine shelter occupancy in this case. Feeding and mating was unaffected by social status in our populations. This is a surprising result given current views on the role of dominance and aggression in many animal systems. The consequences of dominance for resource use in crayfish do not follow our current understanding of resource holding potential. We hypothesize that these consequences vary due to changing behavioural motivations in different social contexts. Future studies should examine under which conditions dominance may impact feeding and mating and whether differential resource use results in differential reproductive success. [ABSTRACT FROM AUTHOR]

The phylogenetic position of the four East Asian freshwater crayfish species of the genus Cambaroides is not settled. Morphological phylogenetic analyses suggest close affinities of Cambaroides with North American Cambaridae. This view is based mainly on characters of the male and female reproductive organs. In contrast, the only molecular phylogenetic analysis so far available leaves the phylogenetic position of Cambaroides unresolved. The question of whether Cambaroides is monophyletic or paraphyletic has so far been neither addressed morphologically nor with molecular data sets. Here we present the first comprehensive phylogenetic analysis of all four currently described species of Cambaroides in the framework of Northern Hemisphere freshwater crayfish (Astacoidea) relationships based on partial sequences of two mitochondrial genes ( CO1 and 12S rRNA). Despite some evidence in favour of a monophyletic Cambaroides more data is needed to resolve this question. Our analyses suggest a close relationship of the North American Cambaridae and the European Astacidae, leaving the Asian Cambaroides basal to them. If these results hold true the similar reproductive organs of Cambaroides and American Cambaridae must be either homoplastic or ancestral for Northern Hemisphere Astacoidea. [ABSTRACT FROM AUTHOR]

Third-instar young-of-the-year (YOY) and juvenile Procambarus acutus acutus and P. clarkii stocked in aquaria, rice forage microcosms and a culture pond were evaluated in intraspecific- and interspecific-competitive settings. Procambarus acutus acutus YOY, which were larger than P. clarkii YOY at stocking, grew and survived at significantly greater rates over fall-, winter- and spring-temperature courses in aquaria. Juvenile P. a. acutus starting an aquarium experiment with a mean total length (TL) size advantage survived at a significantly greater rate than P. clarkii juveniles. Growth rate of similar-sized stocked P. a. acutus juvenile was significantly faster than that of P. clarkii juveniles in the same microcosms. Survival of juvenile P. clarkii in the microcosms with P. a. acutus was significantly less than when stocked alone. Estimated survival of 2200 P. a. acutus and 2200 P. clarkii YOY in a culture pond over a 174-day grow-out period was 84% and 57% respectively. Growth rate of these YOY P. a. acutus and P. clarkii was 0.48 and 0.40 mm TL day−1. The body-size advantage at hatching and through the faster growth of P. a. acutus was important in defining competitive interaction with P. clarkii. [ABSTRACT FROM AUTHOR]

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The article presents information about crayfish species. Astacus leptodactylus and Astacus pachypus live in waters of up to 14 ppt salinity in the Caspian Sea. A. leptodactylus, the only crayfish native to Turkish waters, is known from estuarine environments. Various studies have been conducted on determining the salinity tolerance of a number of crayfish species through survival and growth trials. Some researchers state that their ability to colonize the estuarine environment may be restricted to areas of low salinity due to the adverse effects of sea water on egg development and hatching. Hence, consideration of a brackish-water environment may be more realistic.

Juvenile (mean weight 8.1 g) Australian red claw crayfish, Cherax quadricarinatus, were stocked in July at three rates of 12,000/ha, 18,000/ha, and 24,000/ha into two, 0.02-ha earthen ponds in a cool temperature region of the United States (Kentucky) and grown for 70 days. Red claw were fed a pelleted marine shrimp diet twice daily. Ponds had continual aeration provided. Dissolved oxygen and temperature were measured twice daily (0900 and 1530 hours); total ammonia nitrogen (TAN), nitrite, and alkalinity were measured twice weekly, and pH was measured daily. At harvest, there were no significant (P > 0.05) differences in final individual weight, percentage weight gain, specific growth rate, feed conversion ratio, percentage survival, yield, and economic return among all treatments and averaged 58.4 g, 805%, 3.04%/ day, 7.47, 42.7%, 461 kg/ha, and -$2659/ha, respectively. There were no significant (P > 0.05) differences in the percentage of males and females harvested from the ponds among any stocking rate with males comprising 48.2% and females comprising 51.8%. Final individual weight of males and females was not significantly (P > 0.05) different among all treatments. These data indicate that there is no advantage to stocking red claw at rates below 24,000/ha in terms of growth, survival, yield, and economic return and that red claw can grow to marketable size in a cooler temperate region of the United States with a short (<110 days) growing season by stocking a larger-size (8 g) red claw. [ABSTRACT FROM PUBLISHER]

We compared the dietary composition, feeding preferences, and food selection of the introduced crayfish, Procambarus clarkii in a natural and a transformed freshwater marsh (rice field) in the lower Guadalquivir basin (southern Spain). Both habitats differed in hydroperiod and food item diversity. Food item diversity in crayfish stomachs is correlated with prey availability, which is significantly higher in the natural marsh. Herrera's index was low in both areas if compared with the theoretical maximum. P. clarkii behaves like a generalist in this area and individual crayfish have very similar feeding preferences. The most frequent items in the stomach were fresh macrophytes, detritus, and sediment grains. However, especially in the untransformed marsh, insect larvae formed an important part of the crayfish's diet, up to 67% by occurrence, with a marked seasonal pattern: crayfish in this area consumed significantly more animal prey in spring than in winter. P. clarkii positively selects for insect larvae (mayflies, chironomids), snails, and microcrustaceans except ostracodes. Negative selection against oligochaetes is explained by their burrowing behaviour and the difficulty to detect them in the stomachs. Cannibalism is stronger in the rice fields as a consequence of high crayfish densities. Animal food for adult P. clarkii is shown to be more important than previously reported. Overestimation of herbivory and detrivory in this omnivorous species might be due to serious methodological drawbacks associated with stomach content analyses. [ABSTRACT FROM AUTHOR]

In order to improve our general knowledge on the distribution of the various species of freshwater crayfish of the family Astacidae in Croatia, we gathered all the available unpublished data, as well as data from the literature and those of our own investigations. Our research confirmed the presence of three crayfish species in Croatia: Astacus astacus (Linnaeus, 1758). Austropotamobius torrentium (Schrank. 1803), and Austropotamobius pallipes (Lereboullet. 1858), and we officially recorded the presence of Astacus leptodactylus Eschseholtz, 1823 and Orconectes limosus (Rafinesque, 1817). Biogeographical data suggest the following distribution pattern: A. astacus is distributed in the continental part of Croatia, forming both river and lake populations, A. pallipes is distributed in south and southwest Croatia (Lika Istria Dalmatia and on some islands in the Adriatic Sea) A torrentium can he found in streams at higher altitudes in the continental part of Croatia. Finally A Ieptodactylus is found in the rivers of eastern and central Croatia (Slavonia and Posavina). while O. limosus was discovered recently in marshes of the Nature Park Kopaëkint (Slavonia). Some mixed populations of A. astacus and A. torrentium were detected. Some specimens of A. pallipes and A. torrentium were found in underground habitats Research on the distribution of' freshwater crayfish should he more intensive, and will he continued in the future. [ABSTRACT FROM AUTHOR]