Mating and spawning of the crayfish Austropotamobius pallipes (Crustacea: Astacidae)

Mating and spawning of the crayfish Austropotamobius pallipes (Lereboullet) is described and compared with the accounts of this behaviour in Orconectes limnosus, Pacifastacus trowbridgii and Homarus amerieanus.     

The setae of Austropotamobius pallipes (Crustacea: Astacidae)

The author presents here the results of an introductory study into the setal armature of the British species of crayfish, Austropotamobius pallipes (Lereboullet, 1858). Using an ordinary optical microscope, it is demonstrated that a considerable variety of setae exist on the body and appendages of A. pallipes. These setae are described, and their distribution indicated. The setae fall into two main groups:
(1) Setae with relatively thick walls and inconspicuous ampulla, and having no basal septum.
(2) Those setae with relatively thin walls, a well-developed ampulla and basal septum. Further subdivisions of these two groups are made on the bases of outgrowths and outlines of the setal wall. Finally, the significance of the distribution and the variation, is discussed in relation to crayfish behaviour and function, linking the observed morphological facts with the results of some current electro-physiological experiments performed on related decapods.     

Branchiobdellidan infestation on endangered white-clawed crayfish (Austropotamobius pallipes) in the UK

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.     

Laboratory breeding studies of freshwater crayfish, Austropotamobius pallipes (Lereboullet)

SUMMARY. 1. Mature crayfish, collected from an Irish lake before breeding had started, were held in breeding combinations and their mating and brooding activities observed.
2. All mating attempts were initiated by the male. A single mating led to spawning within 6 days but a subsequent mating cancelled the effects of the first. Males mated more often when there were more females present. Males lacking a major cheliped mated less often than did normal males.
3. Larger males mated more often than did smaller males, and although males showed no female size preference, matings were less frequent and generally unsuccessful when males were much larger than females; the female was usually killed. Large females mated successfully with smaller males.
4. Females held at high densities with a larger male mated earlier than at low densities. However, aggression also increased with density; at high densities males fought and killed females.
5. Males held in pairs without females fought; in occasional mating attempts spermatophores were not positioned correctly. Paired females rarely fought; all spawned normally although unmated. Although their eggs soon died and were removed during grooming, brooding behaviour continued for at least 2 months.
6. Brooding females held in pairs shed pleopodal eggs during aggressive encounters. Females held singly showed a lower initial rate of egg loss.     

Reproduction in an Irish lake population of the crayfish Austropotamobius pallipes (Lerehoullet)

SUMMARY. 1. Mature crayfish were collected in 1984 from an alkaline Irish lake before and after the mating season.
2. There was some correlation between frequency of mating and decrease in vasa deferentia weight in captive males, but in the field vasa deferentia weight losses were highly variable. The data indicate that one third of adult males may not have mated in the wild.
3. All females appear to have spawned, whether or not mated, with an average 85% reduction in ovary weights over the season.
4. Pleopodal egg counts directly after laboratory spawning were on average 81% of ovarian counts; in the field, an estimated 50 days after spawning, they were only 61% of estimated ovarian egg numbers.
5. Average ovarian egg size was positively correlated with female size. Also, larger crayfish had a wider range of egg sizes than smaller crayfish.
6. It is suggested that aggression and competition for shelter among brooding females may result in a progressive loss of eggs.     

Respiration in relation to ion uptake in the crayfish Austropotamobius pallipes (Lereboullet).

1. O2 uptake was determined for periods of 23-46 h in salt-depleted crayfish held in deionized water (DW) or Na-free media at 10 degrees C. These media were replaced by artificial lakewater media (ALW) containing 0-2-0-6 mM Na and O2 uptake was again determined for periods of 24-66 h. 2. During net ion uptake in ALW the metabolic rate was either elevated or depressed. Standard metabolism in ALW altered by amounts equivalent to 0-1 - 15-5% (mean 6-4 (15) +/- 4-4% S. D.) of the metabolic rate measured during salt-depletion. On three occasions the metabolic rate was elevated by 22-0 - 66-7%, but some of this increase may have been due to locomotor activity. 3. The calculated values for thermodynamic work involved in ion transport were 0-056 - 0-268 J/10 g. h at 10 degrees C, or 1-5 - 7-2% of the mean standard metabolic rate. Most of the observed changes in metabolic rate lie within the limits of experimental error (ca. +/- 7%). Hence the energetic cost of ion transport is too small for direct measurement in intact crayfish.     

Mitochondrial DNA variation and population genetic structure of the white-clawed crayfish, Austropotamobius pallipes pallipes

Here we report a high level of mtDNA variationfrom RFLP analysis within A. p. pallipes from 21 French and 4British populations. Seventeen haplotypes were recorded among 269individuals. Nucleotide sequence divergence (p) among mtDNAhaplotypes ranged from 0.0019 to 0.0425. Nucleotide diversity ()ranged from 0.01 to 0.006 (mean = 0.0031) and from 0 to 0.001(mean = 0.00037) for populations located in southern and northernFrance, respectively. Graphical representation from principalcoordinate analysis based on Nei's genetic distance values amongpopulations showed two groups, cluster A, including the 16populations sampled in the north-western and north-easternFrance, England and Wales and cluster B containing 9 populationssampled in the central and southern of France. No geneticdifferences were noted among the most northern French and Englishpopulations whereas marked interpopulation genetic diversity wasobserved in southern populations. Such genetic heterogeneityamong populations of A. p. pallipes appears to be related tohabitat fragmentation and subsequent recolonizations fromrefugial areas during the Pleistocene. Implications for theconservation of A. p. pallipes are discussed.     

A study of reproductive females of the freshwater crayfish Austropotamobius pallipes

Details of the female annual reproductive cycle in the population from Northumberland are given. Mating occurs in October and is followed by egg laying in early November. Eggs are carried by females until the following July–August when hatching occurs. The smallest berried female caught was 25 mm carapace length (C.L.) and this was chosen as the minimum size for adult females. Only 40–50% of adult females, hand-caught, were berried in the Spring following egg laying; but this percentage was low largely because few females in the size classes below 28 mm C.L. were berried. The reasons for adult females being non-reproductive in a year are discussed.     

The distribution of the crayfish, Austropotamobius pallipes, in British waters

SUMMARY. The distribution of Austropotamobius pallipes , the only freshwater crayfish indigenous to the British Isles, is examined using over 300 records collected since 1970. The majority of records are for England where crayfish are found in areas associated with base-rich easily weathered substrata. Waters containing crayfish tend to be in the pH range 7–9, with calcium levels above 5 mg l⁻¹. Crayfish are found in a wide variety of habitats ranging from deep water-filled quarries with a soft substratum to shallow fast-flowing streams.     

Metal-protein binding patterns in the hepatopancreas of the crayfish (Austropotamobius pallipes) during short term cadmium stress

Cd-binding patterns in the hepatopancreas of the crayfish (Austropotamobius pallipes) have been analysed in response to the administration of a single dose of Cd ions. Four main components, with apparent molecular weights of 3-4, 12, 20 and greater than 70 K daltons, have been isolated from soluble cell fractions. The variation in molar metal/protein ratios of these components is discussed in terms of the uptake, transfer and detoxification of Cd in the hepatopancreas. A model is proposed which describes Cd flux at the subcellular level and indicates that metallothionein-like proteins may mediate in this process.     

Immunological evidence for progesterone and estradiol receptors in the freshwater crayfish Austropotamobius pallipes

In this article, we present evidence for progesterone and estradiol receptors (PR and ER, respectively) in the female of the crayfish Austropotamobius pallipes. To our knowledge, this is the first report of sex steroid receptors in crustaceans. By using immunohistochemistry and Western blotting approaches and employing three different antibodies against PR (human PR, chicken PR-hinge region, and chicken PR A/B domain) and antibodies against human ER, we showed the presence of PR in the ovary and hepatopancreas and ER in the hepatopancreas of the freshwater crayfish A. pallipes. The immunological characteristics and the tissue localization suggest a relatedness with both PR and ER in vertebrates along with their involvement in the modulation of reproductive functions in this crustaceans.     

Histopathological survey of pathogens and commensals of white-clawed crayfish (Austropotamobius pallipes) in England and Wales

A histopathological survey of white-clawed crayfish (Austropotamobius pallipes) from six rivers in England and Wales was conducted between November 2007 and September 2011. A. pallipes bacilliform virus (ApBV) was present in four samples; infected crayfish showed pathological responses ranging from mild hypertrophy of infected nuclei and emargination of chromatin through to loss of architecture of the hepatopancreatic cells. Crayfish were found to be hosts to two different ciliate species, mites, nematodes, digeneans and the microsporidian Thelohania contejeani. The variation in disease presence between populations highlights the importance of conducting appropriate surveys of native crayfish prior to movement of animals to refugia sites for relocation, restocking or breeding programmes.     

Geographical variation of mitochondrial DNA between populations of the white-clawed crayfish Austropotamobius pallipes

1. The white-clawed crayfish Austropotamobius pallipes has a widespread distribution in Europe, but since the last century its distribution has been severely affected by a combination of factors, particularly the disease crayfish plague, introduced by foreign crayfish species. At present A. pallipes is considered as vulnerable and endangered and measures are being taken in a number of countries to conserve it.
2. The application of genetics to conservation is of practical value particularly where restocking is being considered. This study assesses levels of genetic differentiation from an analysis of mitochondrial DNA (mtDNA) variation by restriction fragment length polymorphism of four populations sampled on a European scale. Six different composite haplotypes were detected among sixty-four crayfish representing the four populations. mtDNA nucleon diversity values within species ranged from 0.63% to 12.35%. A close genetic similarity was found between British and French populations of A. pallipes .
3. Results show that mtDNA can be as a suitable diagnostic marker for measuring genetic diversity between crayfish populations and that such information is of use in planning crayfish conservation strategies.     

Ranging behaviour of a large freshwater invertebrate, the white-clawed crayfish Austropotamobius pallipes

• 1 Radio‐telemetry and mark‐recapture methods were used to study the summer movements of adult and juvenile white‐clawed crayfish, Austropotamobius pallipes from a wild population in a small braided stream, Dalton Beck, North Yorkshire, U.K. Radio‐transmitters were attached to the chelae of 18 large (> 35 mm carapace length) crayfish and individuals were subsequently located to within 0.15 m. Additionally a total of 888 crayfish were marked with carapace brands, and 83 were recaptured.
• 2 Radio‐tracked crayfish exhibited significantly greater local activity at dusk (21.00–00.00) than at dawn (03.00–06.00), or during morning (09.00–12.00) and afternoon (15.00–18.00) monitoring periods.
• 3 The greatest movements of radio‐tracked crayfish occurred within 2 days of release. After this time, periods of residence were interspersed by movements to new locations, interpreted as establishment of ephemeral home areas. It is suggested that the initial large movements were the result of a ‘fright response’ following capture.
• 4 Movements varied widely between individuals, some moving more than 300 m in 10 days, while others showed little movement over an equivalent time period. Mean (±SE) daily movements were 4.6 ± 3.0 m for males and 1.5 ± 1.0 m for females. Although crayfish often used specific home sites for in excess of 7 days, displaced animals did not return to home sites.
• 5 The total distances travelled and the mean distance travelled per day by individual radio‐tagged crayfish did not differ significantly between upstream or downstream directions or between males and females. This was also the case for marked crayfish used in mark‐recapture studies.
• 6 Positive correlations between distance moved per day and size (carapace length) were found for downstream movements by male and female crayfish, but not for upstream movements.
• 7 Some preliminary observations of the response of crayfish to flood events suggested that these could be catastrophic with two out of five tracked crayfish found dead after a high stream‐discharge event.

     

Geographical variation of mitochondrial DNA between populations of the white-clawed crayfish Austropotamobius pallipes

1. The white-clawed crayfish Austropotamobius pallipes has a widespread distribution in Europe, but since the last century its distribution has been severely affected by a combination of factors, particularly the disease crayfish plague, introduced by foreign crayfish species. At present A. pallipes is considered as vulnerable and endangered and measures are being taken in a number of countries to conserve it.
2. The application of genetics to conservation is of practical value particularly where restocking is being considered. This study assesses levels of genetic differentiation from an analysis of mitochondrial DNA (mtDNA) variation by restriction fragment length polymorphism of four populations sampled on a European scale. Six different composite haplotypes were detected among sixty-four crayfish representing the four populations. mtDNA nucleon diversity values within species ranged from 0.63% to 12.35%. A close genetic similarity was found between British and French populations of A. pallipes .
3. Results show that mtDNA can be as a suitable diagnostic marker for measuring genetic diversity between crayfish populations and that such information is of use in planning crayfish conservation strategies.     

Origin and colonization history of the white-clawed crayfish,Austropotamobius pallipes,in Ireland

The presence of the white-clawed crayfish Austropotamobius pallipes complex in Ireland is suspected to be a result of human translocations. Two hypotheses have been formulated about the origin of the crayfish: from British populations or from western French populations. In order to resolve this question, nine Irish crayfish populations (a total of 124 individuals) were sampled along a south-north cline and investigated by combining two molecular markers: mtDNA and RAPDs. The mtDNA marker, analysed by RFLP on the entire molecule, showed an absence of polymorphism within and among Irish populations. The RFLP haplotype found in Irish populations was only recorded in western French populations and was different from those found in English populations. This result may be explained by a human introduction of crayfish to Ireland from western French populations. RAPD analysis showed a clinal reduction of genetic variability within Irish populations from south to north, associated with an increase in their genetic differentiation. A stepwise model of translocation from the south to the north of Ireland is proposed and discussed.