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White-clawed crayfishAustropotamobius 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 monitoringA. pallipespopulations. 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.

Astacus leptodactylusEschscholtz, 1823 is an important, marketable species of crustacean, consumed intensely as a luxury food in many countries. BecauseA. leptodactylusis less cannibalistic than other crayfish species, is more fecund, and has a fast growth rate, it is accepted as a considerably suitable crayfish for culturing in extensive pond systems. Information on the reproductive biology and anatomy of crayfish is important for developing suitable production methods. Sex recognition may also be essential in separating males and females in crayfish rearing (i.e., to prevent cannibalism, males grow faster than females). Although male reproductive system morphology and spermatophore formation in crayfish, includingA. leptodactylus, have been studied in detail, this study is the first to demonstrate the visibility of precursors of the gonopods and, thus, the actual presence of gonopods, which of course determine the male sex, in a freshwater crayfish. The present study shows that the first signs of secondary sexual characters (i.e., precursors of the gonopods) can be distinguished in the form of small tubercles on the first abdominal somite in male stage 4 juveniles, and the gonopods themselves are distinguishable in male stage 5 juveniles inA. leptodactylus. In conclusion, sex differentiation inA. leptodactyluscan be realized already in stage 4 juveniles. Further studies should be carried out on the presence and shape of precursors of gonopods in stage 4 and gonopods in stage 5 juveniles of species of astacid crayfish in order to facilitate solving taxonomic problems in the family Astacidae.

In this study, the levels of 17β-oestradiol (E2) and 17α-hydroxyprogesterone in the haemolymph, ovary and hepatopancreas of the freshwater narrow-clawed crayfish, Astacus leptodactylus (Eschscholtz, 1823) were analysed in different stages of oocyte development. In recent years, the occurrence of vertebrate-type steroid hormones, E2 and 17α-hydroxyprogesterone, has been reported in a few decapods, although their precise role in female reproduction is not fully elucidated. Thirty specimens of A. leptodactylus were caught at Aras Dam (Western Azerbaijan, Iran) and maintained under experimental conditions (at 25°C with a photoperiod of 14 : 10 hours light/dark) from November to March 2010. For steroid extraction, 3 ml haemolymph was withdrawn from the pericardial cavity with a syringe, and frozen at −20°C. The pieces of ovary and hepatopancreas were homogenized with phosphate buffer (pH 7.8) and, centrifuged at 3000 rpm for 15 min at 4°C as well. It was observed that the level of E2 increased in haemolymph and ovary during vitellogenesis, and decreased in the hepatopancreas. The level of 17α-hydroxyprogesterone was enhanced in haemolymph and ovary during the maturation stage. Maximum levels of E2 and 17α-hydroxyprogesterone were present in the ovary. The results point out the possible involvement of vertebrate-type steroids in the endocrine regulation of the ovarian cycle of A. leptodactylus.

[The egg case is an extracellular structure that surrounds an egg cell and the embryo after fertilization. Its basic function is to protect the embryo from potentially harmful aspects of the external environment. Changes in the structure of the egg case at different stages of embryogenesis in the crayfish Astacus leptodactylus were studied, with observations made at the beginning of egg incubation, during incubation, and at the time of hatching. We studied the changes using images taken with transmission electron microscopy (TEM) and scanning electron microscopy (SEM). The egg case is made of three layers that are all close together. The outer layer was 4.59±0.23 μ m thick and composed of an electron-dense material; its external structure was rough. The middle layer was the thickest at 8.94±0.29 μ m and was slightly folded. It was made of polyhedral grains, interspersed with multiple aeropylar areas and channels. This second (middle) layer consisted of two sublayers of equal thickness but with variable grain size and aeropyle structure. The third and innermost layer was 3.14±0.33 μ m thick and made of tightly packed grains, smaller than those in the middle layer. It included a few, small aeropylar channels. La membrane de l'œuf est une structure extra embryonnaire qui entoure l'œuf ou l'embryon apres la fecondation. Sa fonction de base est de proteger l'embryon des aspects potentiellement nuisibles de l'environnement externe. Les changements de la structure de la membrane de l'œuf chez l'ecrevisse Astacus leptodactylus ont ete etudies, avec des observations faites au debut de l'incubation de l'œuf, durant l'incubation et au moment de l'eclosion. Nous avons etudie les changements a partir d'images prises en microscopie electronique a transmission (TEM) et a balayage (SEM). La membrane de l'œuf est faite de trois couches serrees. La couche externe (4,59±0,23 μ m d'epaisseur) est composee de materiel dense aux electrons ; sa surface externe est ruguenx. La couche mediane est la plus epaisse (8,94±0,29 μ m) et est legerement pliee. Elle est constituee de grains polyedriques entrecoupes par de multiples zones aeropyles et des canaux. Cette couche mediane consiste en deux sous-couches de meme epaisseur mais avec des tailles de grains et des structures aeropyles variables. La troisieme couche interne (3.14±0.33 μ m d'epaisseur) est faite de grains etroitement serres, plus petits que ceux de la couche moyenne. Elle comporte quelques petits canaux aeropyles. , The egg case is an extracellular structure that surrounds an egg cell and the embryo after fertilization. Its basic function is to protect the embryo from potentially harmful aspects of the external environment. Changes in the structure of the egg case at different stages of embryogenesis in the crayfish Astacus leptodactylus were studied, with observations made at the beginning of egg incubation, during incubation, and at the time of hatching. We studied the changes using images taken with transmission electron microscopy (TEM) and scanning electron microscopy (SEM). The egg case is made of three layers that are all close together. The outer layer was 4.59±0.23 μ m thick and composed of an electron-dense material; its external structure was rough. The middle layer was the thickest at 8.94±0.29 μ m and was slightly folded. It was made of polyhedral grains, interspersed with multiple aeropylar areas and channels. This second (middle) layer consisted of two sublayers of equal thickness but with variable grain size and aeropyle structure. The third and innermost layer was 3.14±0.33 μ m thick and made of tightly packed grains, smaller than those in the middle layer. It included a few, small aeropylar channels. La membrane de l'œuf est une structure extra embryonnaire qui entoure l'œuf ou l'embryon apres la fecondation. Sa fonction de base est de proteger l'embryon des aspects potentiellement nuisibles de l'environnement externe. Les changements de la structure de la membrane de l'œuf chez l'ecrevisse Astacus leptodactylus ont ete etudies, avec des observations faites au debut de l'incubation de l'œuf, durant l'incubation et au moment de l'eclosion. Nous avons etudie les changements a partir d'images prises en microscopie electronique a transmission (TEM) et a balayage (SEM). La membrane de l'œuf est faite de trois couches serrees. La couche externe (4,59±0,23 μ m d'epaisseur) est composee de materiel dense aux electrons ; sa surface externe est ruguenx. La couche mediane est la plus epaisse (8,94±0,29 μ m) et est legerement pliee. Elle est constituee de grains polyedriques entrecoupes par de multiples zones aeropyles et des canaux. Cette couche mediane consiste en deux sous-couches de meme epaisseur mais avec des tailles de grains et des structures aeropyles variables. La troisieme couche interne (3.14±0.33 μ m d'epaisseur) est faite de grains etroitement serres, plus petits que ceux de la couche moyenne. Elle comporte quelques petits canaux aeropyles. ]

This study reports on the chromosome number and karyological characteristics of the endangered species of European crayfish, Astacus astacus and A. leptodactylus (Decapoda, Astacidae), both native to Croatian freshwater habitats. The karyotype of A. astacus and A. leptodactylus consists of 2n = 176 and 2n = 180 chromosomes, respectively. The haploid chromosome complement of A. astacus consists of 52 metacentric, 35 metacentric-submetacentric, and 1 acrocentric chromosomes. Fluorochrome staining with 4,6-diamino-2-phenylindole (DAPI) has revealed that the karyotypes of A. astacus and A. leptodactylus are characterized by large heterochromatic blocks located at centromeric and intercalary positions on the chromosomes. Interstitial heterochromatic blocks were more frequent in A. astacus than in A. leptodactylus. In both species pairing of chromosomes in meiosis was regular with the majority of bivalents in a ring- and a dumbbell-form. Fluorescence in situ hybridization (FISH) has revealed that two 45S rDNA loci were present in the investigated species. In A. astacus one of the two 45S rDNA-bearing chromosome pairs was highly heteromorphic, exhibiting a three-fold size difference between 45S rDNA sites on homologous chromosomes. Such a size difference was significantly less pronounced in A. leptodactylus. The karyotype differences between A. astacus and A. leptodactylus suggest changes in chromosome number as well as position of repetitive DNAs have played a role in the karyotype evolution of the species of Astacus.

[Two species of cambarids have been reported for the Yucatan Peninsula, Procambarus llamasi and P. pilosimanus, the latter with a distribution that stretches from the south of Veracruz to the south of Campeche. However, during the last decade only the presence of P. llamasi has been reported; as a consequence, and also because of the biogeographic isolation of the Laguna de Chichancanab, we here investigated two southern populations, Procambarus sp. from Laguna de Chichancanab, Quintana Roo (LCh) and Procambarus llamasi from Ignacio Zaragoza, Campeche (IZa). We investigated these at the molecular level in order to determine if they are independent genetic units. The levels of genetic heterogeneity of the mitochondrial r16S and subunit I of the cytochrome oxidase (CO-I) genes are thus evaluated and contrasted to the levels of the cambarellinid, Cambarellus montezumae from the Xochimilco Channels, D.F. (XCh). The phylogenetic relations of these populations in relation to other Neartic and Neotropical astacoids (Astacidae and Cambaridae) and Caribbean atyids (Atyidae) were investigated. Levels of genetic diversity (h and π) in both r16S and CO-I were lower in the southeastern populations in relation to the Cambarellinae from central Mexico. For instance, π ranged from 0.00000 to 0.00149 for r16S and CO-I, respectively, in the southeastern populations, whereas the central population showed levels that ranged from 0.00250 to 0.00232 for the same gene regions. Both gene regions indicate significant levels of structuring among the southeastern populations (F ST, 0.714 and 0.612, P < 0.0001, for r16S and CO-I), and these results are supported by the lack of actual gene flow. However, in order to confirm this hypothesis a larger number of populations along the range of distribution of the species should be tested. The phylogenetic reconstruction by maximum parsimony (MP), minimum evolution (ME), and maximum likelihood (ML) of these populations and other astacids and atyids, confirms the monophyly of the two southeastern populations (P. llamasi) as well as of C. montezumae, and suggests that Cambaridae constitutes a non-monophyletic assemblage, a hypothesis herein confirmed by a total evidence Bayesian analysis. Se han reportado dos especies de cambaridos para la Peninsula de Yucatan, Procambarus llamasi y P. pilosimanus, este ultimo con una distribucion que va del sur de Veracruz al sur de Campeche. Sin embargo, durante la ultima decada solo se ha registrado la presencia de P. llamasi. Ademas y debido al aislamiento de la Laguna de Chichancanab, en el presente trabajo se investigan a nivel molecular a dos poblaciones surenas, Procambarus sp. de la Laguna de Chichancanab, Quintana Roo (LCh) y Procambarus llamasi de Ignacio Zaragoza, Campeche (IZa), para determinar si son unidades geneticas independientes. Se evaluan y contrastan los niveles de heterogeneidad de las subunidades mitocondriales r16S y citocromo oxidasa I (CO-I) con relacion a las del cambarelinido Cambarellus montezumae de los Canales de Xochimilco, D.F. (XCh). Se investigan las relaciones filogeneticas de estas poblaciones en relacion a especies de astacoideos Nearticos y Neotropicales (Astacidae y Cambaridae) y de atyidos caribenos (Atyidae). Los niveles de diversidad genetica (h and π) para r16S y CO-I fueron mas bajas en las poblaciones surenas en relacion al cambarelinido del centro de Mexico. Por ejemplo, π vario de 0,00000 a 0,00149 para r16S y CO-I, respectivamente, para las poblaciones surenas, mientras que para la poblacion central los valores variaron entre 0,00250 y 0,00232 para las mismas regiones. Ambas regiones genicas mostraron niveles significativos de estructuracion entre las poblaciones surenas (F ST, 0,714 y 0,612, P < 0,0001, para r16S y CO-I), resultados que son apoyados por los bajos niveles de flujo genico, sin embargo un mayor numero de poblaciones a lo largo de la distribucion de la especie deberan ser muestreadas para corroborar dicha hipotesis. La reconstruccion filogenetica de estas poblaciones y otros astacoideos y atyidos y por medio de maxima parsimonia (MP), minima evolucion (ME) y maxima verosimilitud (ML) confirman la monofilia de las dos poblaciones surenas (P. llamasi), asi como la de C. montezumae y sugieren que la familia Cambaridae es un ensamble no-monofiletico, hipotesis que se confirma con un analisis Bayesiano de evidencia total., Two species of cambarids have been reported for the Yucatan Peninsula, Procambarus llamasi and P. pilosimanus, the latter with a distribution that stretches from the south of Veracruz to the south of Campeche. However, during the last decade only the presence of P. llamasi has been reported; as a consequence, and also because of the biogeographic isolation of the Laguna de Chichancanab, we here investigated two southern populations, Procambarus sp. from Laguna de Chichancanab, Quintana Roo (LCh) and Procambarus llamasi from Ignacio Zaragoza, Campeche (IZa). We investigated these at the molecular level in order to determine if they are independent genetic units. The levels of genetic heterogeneity of the mitochondrial r16S and subunit I of the cytochrome oxidase (CO-I) genes are thus evaluated and contrasted to the levels of the cambarellinid, Cambarellus montezumae from the Xochimilco Channels, D.F. (XCh). The phylogenetic relations of these populations in relation to other Neartic and Neotropical astacoids (Astacidae and Cambaridae) and Caribbean atyids (Atyidae) were investigated. Levels of genetic diversity (h and π) in both r16S and CO-I were lower in the southeastern populations in relation to the Cambarellinae from central Mexico. For instance, π ranged from 0.00000 to 0.00149 for r16S and CO-I, respectively, in the southeastern populations, whereas the central population showed levels that ranged from 0.00250 to 0.00232 for the same gene regions. Both gene regions indicate significant levels of structuring among the southeastern populations (FST, 0.714 and 0.612, P < 0.0001, for r16S and CO-I), and these results are supported by the lack of actual gene flow. However, in order to confirm this hypothesis a larger number of populations along the range of distribution of the species should be tested. The phylogenetic reconstruction by maximum parsimony (MP), minimum evolution (ME), and maximum likelihood (ML) of these populations and other astacids and atyids, confirms the monophyly of the two southeastern populations (P. llamasi) as well as of C. montezumae, and suggests that Cambaridae constitutes a non-monophyletic assemblage, a hypothesis herein confirmed by a total evidence Bayesian analysis. Se han reportado dos especies de cambaridos para la Peninsula de Yucatan, Procambarus llamasi y P. pilosimanus, este ultimo con una distribucion que va del sur de Veracruz al sur de Campeche. Sin embargo, durante la ultima decada solo se ha registrado la presencia de P. llamasi. Ademas y debido al aislamiento de la Laguna de Chichancanab, en el presente trabajo se investigan a nivel molecular a dos poblaciones surenas, Procambarus sp. de la Laguna de Chichancanab, Quintana Roo (LCh) y Procambarus llamasi de Ignacio Zaragoza, Campeche (IZa), para determinar si son unidades geneticas independientes. Se evaluan y contrastan los niveles de heterogeneidad de las subunidades mitocondriales r16S y citocromo oxidasa I (CO-I) con relacion a las del cambarelinido Cambarellus montezumae de los Canales de Xochimilco, D.F. (XCh). Se investigan las relaciones filogeneticas de estas poblaciones en relacion a especies de astacoideos Nearticos y Neotropicales (Astacidae y Cambaridae) y de atyidos caribenos (Atyidae). Los niveles de diversidad genetica (h and π) para r16S y CO-I fueron mas bajas en las poblaciones surenas en relacion al cambarelinido del centro de Mexico. Por ejemplo, π vario de 0,00000 a 0,00149 para r16S y CO-I, respectivamente, para las poblaciones surenas, mientras que para la poblacion central los valores variaron entre 0,00250 y 0,00232 para las mismas regiones. Ambas regiones genicas mostraron niveles significativos de estructuracion entre las poblaciones surenas (FST, 0,714 y 0,612, P < 0,0001, para r16S y CO-I), resultados que son apoyados por los bajos niveles de flujo genico, sin embargo un mayor numero de poblaciones a lo largo de la distribucion de la especie deberan ser muestreadas para corroborar dicha hipotesis. La reconstruccion filogenetica de estas poblaciones y otros astacoideos y atyidos y por medio de maxima parsimonia (MP), minima evolucion (ME) y maxima verosimilitud (ML) confirman la monofilia de las dos poblaciones surenas (P. llamasi), asi como la de C. montezumae y sugieren que la familia Cambaridae es un ensamble no-monofiletico, hipotesis que se confirma con un analisis Bayesiano de evidencia total.]

[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 Egirdir 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 L 50 in the catch approximates the minimum landing size for this species in Turkey. L 50 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. La presente etude a ete realisee afin d'evaluer les effets de la selectivite de verveux (fyke-nets) de differentes tailles de maille sur Astacus leptodactylus (Eschscholtz, 1823), dans le lac Egirdir en Turquie. Les ecrevisses ont ete echantillonnees mensuellement en utilisant des verveux a mailles de 26 mm (controle), 34 mm (traditionnel), et 42 mm (augmentee) de juillet a decembre 2007. Des differences de taille moyenne, de poids et de nombre d'ecrevisses capturees avec chaque taille de maille ont ete determinees. La longueur et le poids moyens ont ete trouves augmentant proportionnellement a la taille de la maille. Le poids moyen le plus eleve (± SD) (g) (41,07 ± 4,61) a ete obtenu avec la taille de maille de 42 mm, comparativement aux poids moyens de 32,76 ± 4,53 et 29,29 ± 4,37 obtenus avec les mailles de 34 et 26 mm, respectivement. La meme tendance a ete observee pour la longueur moyenne (TL) des ecrevisses collectees a l'aide des mailles de 42, 34, et 26 mm, mais aucune difference significative n'a ete detectee sur la longueur moyenne et le poids chez les mâles et les femelles. Le poids des ecrevisses capturees avec des mailles de 42 mm etait 8,3% plus eleve qu'avec des mailles de 34 mm. Le nombre le plus faible d'ecrevisses a ete obtenu avec la taille de maille de 42 mm, tandis que le plus grand nombre a ete capture avec la maille de 34 mm. Cette etude montre que l'augmentation de la taille de la maille a un effet positif sur la selectivite, parce que la longueur totale moyenne L 50 dans la capture approche la taille legale de peche pour cette espece en Turquie. Les valeurs de L 50 (longueur totale) pour les femelles, mâles et sexes combines etaient 9,93 ± 0,41, 9,73 ± 0,34, et 9,93 ± 0,34 cm pour 42 mm; 6,54 ± 0,60, 7,28 ± 0,30, et 7,09 ± 0,3 cm pour 34 mm, respectivement. Il a ete suppose que la taille de maille de 34 mm, qui est utilisee commercialement, a une faible selectivite. D'autre part, une taille de maille de 34 mm a provoque une perte d'ecrevisses commercialisables parmi les trois tailles de mailles testees. La taille 42 mm a fourni la selection la plus appropriee d'ecrevisses, compare aux tailles d'ecrevisses aux mailles 34 et 26 mm, respectivement. Pendant ce temps, comme la taille de maille augmente, le taux d'echappement de la femelle devient superieur a celui du mâle. Ainsi, l'augmentation de la taille de maille des filets aura un impact positif non seulement en preservant un stock durable, mais aussi en epargnant le travail et le temps passes sur les operations de peche. , 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 Egirdir 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 L 50 in the catch approximates the minimum landing size for this species in Turkey. L 50 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. La presente etude a ete realisee afin d'evaluer les effets de la selectivite de verveux (fyke-nets) de differentes tailles de maille sur Astacus leptodactylus (Eschscholtz, 1823), dans le lac Egirdir en Turquie. Les ecrevisses ont ete echantillonnees mensuellement en utilisant des verveux a mailles de 26 mm (controle), 34 mm (traditionnel), et 42 mm (augmentee) de juillet a decembre 2007. Des differences de taille moyenne, de poids et de nombre d'ecrevisses capturees avec chaque taille de maille ont ete determinees. La longueur et le poids moyens ont ete trouves augmentant proportionnellement a la taille de la maille. Le poids moyen le plus eleve (± SD) (g) (41,07 ± 4,61) a ete obtenu avec la taille de maille de 42 mm, comparativement aux poids moyens de 32,76 ± 4,53 et 29,29 ± 4,37 obtenus avec les mailles de 34 et 26 mm, respectivement. La meme tendance a ete observee pour la longueur moyenne (TL) des ecrevisses collectees a l'aide des mailles de 42, 34, et 26 mm, mais aucune difference significative n'a ete detectee sur la longueur moyenne et le poids chez les mâles et les femelles. Le poids des ecrevisses capturees avec des mailles de 42 mm etait 8,3% plus eleve qu'avec des mailles de 34 mm. Le nombre le plus faible d'ecrevisses a ete obtenu avec la taille de maille de 42 mm, tandis que le plus grand nombre a ete capture avec la maille de 34 mm. Cette etude montre que l'augmentation de la taille de la maille a un effet positif sur la selectivite, parce que la longueur totale moyenne L 50 dans la capture approche la taille legale de peche pour cette espece en Turquie. Les valeurs de L 50 (longueur totale) pour les femelles, mâles et sexes combines etaient 9,93 ± 0,41, 9,73 ± 0,34, et 9,93 ± 0,34 cm pour 42 mm; 6,54 ± 0,60, 7,28 ± 0,30, et 7,09 ± 0,3 cm pour 34 mm, respectivement. Il a ete suppose que la taille de maille de 34 mm, qui est utilisee commercialement, a une faible selectivite. D'autre part, une taille de maille de 34 mm a provoque une perte d'ecrevisses commercialisables parmi les trois tailles de mailles testees. La taille 42 mm a fourni la selection la plus appropriee d'ecrevisses, compare aux tailles d'ecrevisses aux mailles 34 et 26 mm, respectivement. Pendant ce temps, comme la taille de maille augmente, le taux d'echappement de la femelle devient superieur a celui du mâle. Ainsi, l'augmentation de la taille de maille des filets aura un impact positif non seulement en preservant un stock durable, mais aussi en epargnant le travail et le temps passes sur les operations de peche. ]

[The need to elucidate the hatching process in the signal crayfish, Pacifastacus leniusculus , emerged as a result of the paucity of information on hatching mechanisms, perivitelline space, and egg hydration during embryonic development. To elucidate morphomechanical changes in the eggs during embryonic development of the signal crayfish, egg diameter and egg case strength were measured. Embryogenesis itself and hatching mechanisms were observed on live eggs in a special apparatus (a microscope coupled with a digital camera, a computer, and a video-recorder). Changes in egg case structure during embryogenesis and during hatching were analysed using light and scanning electron microscopy. During the period of observation, the eggs were found to continuously increase in volume, from an initial value of 8.87 ± 0.376 to 12.25 ± 0.371 mm 3 at hatching. The egg case strength was initially considerable and exceeded 107.7 ± 11.43 g. It was, however, observed to decrease with time to 38.6 ± 15.34 g of hatching. In addition, the structure of the egg case was observed, just before hatching, to loose its integrity mainly by local absence of the inner layer. On hatching, the case would break down along the embryo's cephalothorax, where it was most conspicuously stretched. La necessite d'etudier le processus d'incubation chez l'ecrevisse « signal », Pacifastacus leniusculus , est apparue du fait du manque d'information sur le mecanisme de l'eclosion et le processus de formation de l'espace peri vitellin et des relations hydriques au cours de developpement embryonnaire. Pour elucider les changements morpho-mecaniques des œufs de l'ecrevisse signal pendant son developpement embryonnaire, le diametre des œufs et la resistance de l'enveloppe de l'œuf ont ete mesures. L'embryogenese et le mecanisme de l'eclosion ont ete observes sur des œufs vivants a l'aide d'un dispositif compose d'un microscope couple avec une camera numerique, un ordinateur et un magnetoscope. Les changements de structure de l'enveloppe de l'ceuf au cours de l'embryogenese et de l'eclosion ont ete analyses a l'aide d'un microscope optique et d'un microscope electronique a balayage. Pendant l'observation une croissance continue du volume des œufs a ete observee depuis une valeur initiale de 8,87 ± 0,376 jusqu'a 12,25 ± 0,371 mm 3 au moment de l'eclosion. La resistance de l'enveloppe de l'œuf au debut du developpement a ete elevee et a depasse 107,7 ± 11,43 g. Cependant, au cours du temps, cette valeur a diminue jusqu'a 38,6 ± 15,34 g au moment de l'eclosion. De plus on a constate que, juste avant l'eclosion, la structure de l'enveloppe de l'oeuf perd son integrite par la disparition locale de la couche interne. A l'eclosion l'enveloppe se fissure le long du cephalothorax de l'embryon la ou il y avait la plus grande tension. , The need to elucidate the hatching process in the signal crayfish, Pacifastacus leniusculus , emerged as a result of the paucity of information on hatching mechanisms, perivitelline space, and egg hydration during embryonic development. To elucidate morphomechanical changes in the eggs during embryonic development of the signal crayfish, egg diameter and egg case strength were measured. Embryogenesis itself and hatching mechanisms were observed on live eggs in a special apparatus (a microscope coupled with a digital camera, a computer, and a video-recorder). Changes in egg case structure during embryogenesis and during hatching were analysed using light and scanning electron microscopy. During the period of observation, the eggs were found to continuously increase in volume, from an initial value of 8.87 ± 0.376 to 12.25 ± 0.371 mm 3 at hatching. The egg case strength was initially considerable and exceeded 107.7 ± 11.43 g. It was, however, observed to decrease with time to 38.6 ± 15.34 g of hatching. In addition, the structure of the egg case was observed, just before hatching, to loose its integrity mainly by local absence of the inner layer. On hatching, the case would break down along the embryo's cephalothorax, where it was most conspicuously stretched. La necessite d'etudier le processus d'incubation chez l'ecrevisse « signal », Pacifastacus leniusculus , est apparue du fait du manque d'information sur le mecanisme de l'eclosion et le processus de formation de l'espace peri vitellin et des relations hydriques au cours de developpement embryonnaire. Pour elucider les changements morpho-mecaniques des œufs de l'ecrevisse signal pendant son developpement embryonnaire, le diametre des œufs et la resistance de l'enveloppe de l'œuf ont ete mesures. L'embryogenese et le mecanisme de l'eclosion ont ete observes sur des œufs vivants a l'aide d'un dispositif compose d'un microscope couple avec une camera numerique, un ordinateur et un magnetoscope. Les changements de structure de l'enveloppe de l'ceuf au cours de l'embryogenese et de l'eclosion ont ete analyses a l'aide d'un microscope optique et d'un microscope electronique a balayage. Pendant l'observation une croissance continue du volume des œufs a ete observee depuis une valeur initiale de 8,87 ± 0,376 jusqu'a 12,25 ± 0,371 mm 3 au moment de l'eclosion. La resistance de l'enveloppe de l'œuf au debut du developpement a ete elevee et a depasse 107,7 ± 11,43 g. Cependant, au cours du temps, cette valeur a diminue jusqu'a 38,6 ± 15,34 g au moment de l'eclosion. De plus on a constate que, juste avant l'eclosion, la structure de l'enveloppe de l'oeuf perd son integrite par la disparition locale de la couche interne. A l'eclosion l'enveloppe se fissure le long du cephalothorax de l'embryon la ou il y avait la plus grande tension. ]

The growth parameters, mortality rates, and recruitment pattern of Astacus leptodactylus from an unexploited area in inland waters of the northern Marmara region were investigated based on lengthfrequency data using FISAT software. Specimens were collected during eight scientific samplings carried out between March 2005 and May 2006. The seasonalized Von Bertalanffy growth function was fitted to the length frequency data (n = 2434) with the following parameters: L ∞ = 80.8 mm, K = 0.405 year−1, C = 1, and WP = 0.90. The study of functional regressions permits us to conclude that the growth of this population is allometric. Natural mortality (M) was estimated at 0.578 year−1 and total mortality at 0.589 year−. The longevity of the crayfish was calculated as t max = 7.4 year. The recruitment pattern shows that there is peak recruitment in May and June.We also estimated the potential instantaneous fishing mortality coefficient at F = 1.53-1.63 year−1, the instantaneous total mortality coefficient at Z = 2.11-2.21 year−1, and the exploitation rate E = 0.72-0.73, all through the length-converted catch curve procedure using the length-frequency data of the fyke-nets of 32 mm polyamide (PA) mesh size (stretched mesh). Les parametres de croissance, les taux de mortalite et le modele de recrutement d'Astacus leptodactylus d'une zone non-exploitee des eaux interieures du nord de la region de Marmara ont ete etudies a partir des donnees longueur-frequence en utilisant le logiciel FISAT. Les specimens ont ete collectes au cours de huit campagnes scientifiques d'echantillonnage menees entre mars 2005 et mai 2006. La fonction de croissance de Von Bertalanffy s'ajuste aux donnees de longueur-frequence (n = 2434) avec les parametres suivants: L ∞ = 80,8 mm, K = 0,405 an−1, C = 1, et WP = 0,90. L'etude des regressions fonctionnelles nous permet de conclure que la croissance de cette population est allometrique. La mortalite naturelle (M) a ete estimee a 0,578 an−1 et la mortalite totale a 0,589 an−1. La longevite de l'ecrevisse a ete calculee comme t max = 7,4 ans. Le modele de recrutement montre un pic de recrutement en mai et juin.Nous avons aussi estime le taux potentiel instantane de mortalite par peche a F = 1,53-1,63 an−1, le taux instantane de mortalite totale a Z = 2,11-2,21 an−1, et le taux d'exploitation a E = 0,72-0,73, par la technique de courbes de prises converties en longueur en utilisant les donnees longueur-frequence a partir des verveux de vide de maille polyamide (PA) de 32 mm.

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 Eschscholtz, 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 be found in streams at higher altitudes in the continental part of Croatia. Finally, A. leptodactylus 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 Kopački rit (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 be more intensive, and will be continued in the future.

Crayfish show many behavioral and morphological adaptations that serve to exploit chemical information in an aquatic environment. The primary chemosensory structure, the outer branch of the antennule, varies morphologically among species. A reasonable approach to the study of these variations is to compare morphological structures from crayfish living in different environments. The potential of this approach was evaluated by comparing the morphology and distribution of chemosensory sensilla (aesthetascs) along antennules of a cave- and a surface-dwelling crayfish. In comparison to the surface-dwelling species ( Orconectes cristavarius ), the cave-dwelling species ( O. australis packardi ) had longer antennules and longer individual aesthetasc sensilla. The surface species, however, had significantly more aesthetascs per annulus and a higher density of aesthetascs towards the distal end of the antennule. These data are discussed in terms of chemical sensitivity and chemoreception in turbulent environments. Les ecrevisses presentent des adaptations comportementales et morphologiques qui servent a exploiter l'information chimique dans un environnement aquatique. La structure chemosensible primaire, la rame externe de l'antennule, varie morphologiquement suivant les especes. Une approche raisonnable de l'etude de ces variations est de comparer les structures morphologiques des ecrevisses vivant dans differents environnements. Le potentiel de cette approche a ete evalue en comparant la morphologie et la repartition des sensilles chemosensibles (aesthetasques) sur les antennules d'une ecrevisse vivant en eaux de surface et d'une ecrevisse vivant en eaux souterraines. Par rapport a l'espece de surface ( Orconectes cristavarius ), l'espece de grotte ( O. australis packardi ) avait de plus longues antennules et de plus longs aesthetasques. L'espece de surface, cependant, avait significativement plus d'aesthetasques par anneau et une densite plus elevee d'aesthetasques vers l'extremite distale de l'antennule. Ces donnees sont discutees en termes de sensibilite chimique et de chemoreception dans les environnements turbulents.

[Die Eier von A. pallipes sind am Weibchen durch einen spiraligen Funikulus befestigt, der bei der Eiablage gebildet wird. Bei seiner Enstchung kommt es zu einer Fusion der weichen Ausenschicht eines frish abgelegten Eies mit einer Gruppe von Borsten (Ooseten), die sich auf den Pleopoden und Sterna des Hinterleibs befinden. Seine endgultige Form erhalt der Funikulus in einer spaten Phase des Eiablagegeschehens., Die Eier von A. pallipes sind am Weibchen durch einen spiraligen Funikulus befestigt, der bei der Eiablage gebildet wird. Bei seiner Enstchung kommt es zu einer Fusion der weichen Ausenschicht eines frish abgelegten Eies mit einer Gruppe von Borsten (Ooseten), die sich auf den Pleopoden und Sterna des Hinterleibs befinden. Seine endgultige Form erhalt der Funikulus in einer spaten Phase des Eiablagegeschehens.]

[Des 20 especes incluses par Girard (1852) dans son travail: "A revision of the North American Astaci with observations on their habits and geographical distribution", deux seulement, Cambarus carolinus Erichson et C. robustus Girard, sont reconnues dans la combinaison meme employee par Girard. Six ont ete placees en synonymie (C. affinis et C. pealei = Orconectes limosus; C. montanus et C. pusillus = C. bartonii; et C. fossor et C. nebrascensis = C. d. diogenes). Les douze qui restent sont traitees comme suit: O. pellucidus, Pacilastacus leniusculus (pour C. oreganus), O. r. rusticus, O. p. pellucidus, C. b. bartonii, C. l. longulus, P. g. gambelli, C. d. diogenes, Procambarus blandingii, P. clarkii, P. a. acatus, P. acutissimus., Des 20 especes incluses par Girard (1852) dans son travail: "A revision of the North American Astaci with observations on their habits and geographical distribution", deux seulement, Cambarus carolinus Erichson et C. robustus Girard, sont reconnues dans la combinaison meme employee par Girard. Six ont ete placees en synonymie (C. affinis et C. pealei = Orconectes limosus; C. montanus et C. pusillus = C. bartonii; et C. fossor et C. nebrascensis = C. d. diogenes). Les douze qui restent sont traitees comme suit: O. pellucidus, Pacilastacus leniusculus (pour C. oreganus), O. r. rusticus, O. p. pellucidus, C. b. bartonii, C. l. longulus, P. g. gambelli, C. d. diogenes, Procambarus blandingii, P. clarkii, P. a. acatus, P. acutissimus.]

[Ein neuer - geographisch disjunkt verbreiteter - Fluskrebs Orconectes transfuga wird aus dem Rogue River, Oregon (U.S.A.) beschrieben. Die neue Art ist am engsten verwandt mit den Unter-arten von O. rusticus, welche, zusammen mit allen anderen Vertretern der Cambarinae (mit Ausnahme von drei mexikanischen Procambarus, und Arten die anderswo eingefuhrt worden sind), auf das Gebiet ostlich der Rocky Mountains beschrankt sind. Es ist unwahrscheinlich, das O. transfuga in Oregon einheimisch ist; vermutlich wurde diese Art dort eingeschleppt., Ein neuer - geographisch disjunkt verbreiteter - Fluskrebs Orconectes transfuga wird aus dem Rogue River, Oregon (U.S.A.) beschrieben. Die neue Art ist am engsten verwandt mit den Unter-arten von O. rusticus, welche, zusammen mit allen anderen Vertretern der Cambarinae (mit Ausnahme von drei mexikanischen Procambarus, und Arten die anderswo eingefuhrt worden sind), auf das Gebiet ostlich der Rocky Mountains beschrankt sind. Es ist unwahrscheinlich, das O. transfuga in Oregon einheimisch ist; vermutlich wurde diese Art dort eingeschleppt.]

[Die Gewebe und Organe von neun Flusskrebs-Arten - Cambarus bartoni, C. diogenes, C. fodiens, C. robustus, Orconectes immunis, O. obscurus, O. propinquus, O. rusticus und O. virilis - aus Zentral- und Sud-Ontario (Kanada), wurden (Dunnschichtchromatographie auf Zellulose Platten) auf Pteridinen untersucht. Zwolf Pteridinen und vier Purinen wurden gefunden; alle Organe und Gewebe enthielten mindestens eine Pteridine. Augen und Hypodermis enthielten die grosste Anzahl, die Cuticula die wenigste Anzahl dieser Stoffe., Die Gewebe und Organe von neun Flusskrebs-Arten - Cambarus bartoni, C. diogenes, C. fodiens, C. robustus, Orconectes immunis, O. obscurus, O. propinquus, O. rusticus und O. virilis - aus Zentral- und Sud-Ontario (Kanada), wurden (Dunnschichtchromatographie auf Zellulose Platten) auf Pteridinen untersucht. Zwolf Pteridinen und vier Purinen wurden gefunden; alle Organe und Gewebe enthielten mindestens eine Pteridine. Augen und Hypodermis enthielten die grosste Anzahl, die Cuticula die wenigste Anzahl dieser Stoffe.]

[Cambarus typhlobius Joseph, 1880 (= Cambarus stygius Joseph, 1882), ein blinder Grottenkrebs der von Joseph aus der Hohle von St. Kanzian gemeldet wurde, gehort nicht der europaischen Fauna an. Aller Wahrscheinlichkeit nach ist der Typus Josephs ein aus der Mammuth-Hohle in Kentucky (U.S.A.) stammendes Exemplar von Orconectes pellucidus (Tellkampf, 1844) das versehentlich mit der Fundortsangabe "St. Kanzianhohle, Krain" versehen war. Eine Nachuntersuchung der Typen des Austropotamobius pallipes bispinosus M. Karaman, 1961, hat ausgewiesen dass die Tiere der Art Cambaroides schrenckii (Kessler, 1874) angehoren., Cambarus typhlobius Joseph, 1880 (= Cambarus stygius Joseph, 1882), ein blinder Grottenkrebs der von Joseph aus der Hohle von St. Kanzian gemeldet wurde, gehort nicht der europaischen Fauna an. Aller Wahrscheinlichkeit nach ist der Typus Josephs ein aus der Mammuth-Hohle in Kentucky (U.S.A.) stammendes Exemplar von Orconectes pellucidus (Tellkampf, 1844) das versehentlich mit der Fundortsangabe "St. Kanzianhohle, Krain" versehen war. Eine Nachuntersuchung der Typen des Austropotamobius pallipes bispinosus M. Karaman, 1961, hat ausgewiesen dass die Tiere der Art Cambaroides schrenckii (Kessler, 1874) angehoren.]

Der genaue Befruchtungsort und die genaue Befruchtungszeit des Austropotamobius pallipes sind nicht bekannt; befruchtete Eier schlupfen in der zweiten Juniwoche aus. Der frischgeschlupfte Krebs hat in diesem ersten Stadium fast noch keine Haare; aber die Position der zukunftigen Haare ist durch Auswuchse auf der Schale angedeutet. Die Antennen haben im ersten Entwicklungsstadium keine funktionstuchtige Statocyste, und auf den beiden Asten sind lediglich winzige Haarkeime sichtbar. Mit Ausnahme der Mandibeln weisen alle Mundpartien nur eine sehr geringe Anzahl fertig ausgebildeter Haare auf, die sich alle in den proximalsten Segmenten befinden. Obwohl die relativen Proportionen der Segmente, aus denen die Korperanhange bestehen, sich von denen im Erwachsenenstadium unterscheiden, sind alle Segmente bereits vorhanden. Lediglich Sonderentwicklungen wie die Schalenkissen auf den Coxopoditen der Maxillen und der Maxillipeden sind noch nicht sichtbar. Die Scherenanhange des frischgeschlupften Krebses sind an ihren distalen Enden typisch gekrummt, und die Scheren selbst sind noch viel weniger von den Schreitfussen differenziert als im erwachsenen A. pillipes. Die Pleopoden sind doppelastig und unbehaart; erst bei der dritten Hautung weisen sie das Haarmuster der Adulti auf. Beobachtungen an frischgeschlupften Krebsen kurz vor der Hautung zeigten, dass Haare sich auf zwei Arten - je nach ihrer Lange und der Tiefe ihrer Einbettung in die Schale - entwickeln. Nach der ersten Hautung ist ein dramatischer Zuwachs an Haaren zu verzeichnen; dieser Zuwachs setzt sich uber die folgenden Entwicklungsstadien hin fort. Die frischgeschlupften Krebse konnen innerhalb von zwei Monaten sexuell differenziert sein, und innerhalb eines Jahres zumindest ausserlich reif erscheinen.

[Procambarus incilis n. sp., ein naher Verwandter von P. hinei (Ortmann), wird an Hand von 16 Exemplaren beschrieben, welche in Tumpeln und Graben der Kustenebene des sudostlichen Teiles von Texas gesammelt wurden., Procambarus incilis n. sp., ein naher Verwandter von P. hinei (Ortmann), wird an Hand von 16 Exemplaren beschrieben, welche in Tumpeln und Graben der Kustenebene des sudostlichen Teiles von Texas gesammelt wurden.]

[Das Eilege-Verhalten von Pacifastacus trowbridgii wird beschrieben. Das Intervall zwischen Kopulation und Laichakt ist charakterisiert durch Wechselfolgen von Putzhandlungen und Graben, deren Intensitat und Dauer zunimmt mit herannahender Laichzeit. Das unmittelbar bevorstehende Laichen kundigt sich durch Zunahme der Agressionshandlungen gegenuber anderen Fluskrebsen an, inklusive gegenuber begatteten Weibchen. Das Laichverhalten ist folgendermasen zu kategorisieren: (1) eine Serie akuter abdominaler Kontraktionen, (2) Einnehmen der Laichposition, (3) Abgabe von Eiern, (4) Ruhepause, (5) Wiedereinnahme der aufrechten Haltung, (6) Drehen. Putzhandlungen nach dem Drehen entfernen die schleimige Hulle, welche die ventrale Oberflache vom Schwanzfacher bis zur Region der Ovidukte bedeckt. Der Laichakt verlauft ahnlich wie bei den Cambarinae., Das Eilege-Verhalten von Pacifastacus trowbridgii wird beschrieben. Das Intervall zwischen Kopulation und Laichakt ist charakterisiert durch Wechselfolgen von Putzhandlungen und Graben, deren Intensitat und Dauer zunimmt mit herannahender Laichzeit. Das unmittelbar bevorstehende Laichen kundigt sich durch Zunahme der Agressionshandlungen gegenuber anderen Fluskrebsen an, inklusive gegenuber begatteten Weibchen. Das Laichverhalten ist folgendermasen zu kategorisieren: (1) eine Serie akuter abdominaler Kontraktionen, (2) Einnehmen der Laichposition, (3) Abgabe von Eiern, (4) Ruhepause, (5) Wiedereinnahme der aufrechten Haltung, (6) Drehen. Putzhandlungen nach dem Drehen entfernen die schleimige Hulle, welche die ventrale Oberflache vom Schwanzfacher bis zur Region der Ovidukte bedeckt. Der Laichakt verlauft ahnlich wie bei den Cambarinae.]