The issue of sea lice (Lepeoptheirus salmonis and Caligus clemensii) transfer from salmon farms to wild salmon is a controversial topic in British Columbia (BC). A series of sea lice epizootics (four in five years) on juvenile chum (Oncorhynchus keta) and pink (0. gorbuscha) salmon in the Broughton Archipelago (BA), an area with the highest density of salmon farms on the west coast, have caused significant concern among conservationists, local First Nations, and the general public over the possible impacts of salmon farms on wild salmon. Key to the debate has been a lack of data on ambient sea lice infection rates on juvenile salmon in the absence of the influence of salmon farms. This work represents one of the first attempts to empirically examine ambient sea lice infection rates on juvenile salmonids. Objectives were to test hypotheses including: geographic variability is a significant factor in sea lice population dynamics, ambient sea lice infection rates on juvenile salmon are low, juvenile salmon susceptibility to sea lice infection, and the influence of salmon farms on ambient sea lice infection rates. Over a three year period, samples of juvenile chum and pink salmon (n=13.874) were collected using a beach seine net in the central coast of British Columbia (Klemtu/Bella iv Bella), a vast area with limited salmon farming activity. and with geography that allowed for simultaneous assessment in the same region of the natural interaction between sea lice and juvenile salmon and the influence of salmon farms on the interaction. Sampling was also conducted in other areas without salmon farms (Southern Gulf Islands: n=3847) and with salmon farms (Broughton Archipelago; n=3911). The results of the field experiments were also used in conjunction with laboratory experiments to examine the susceptibility of juvenile chum vs. pink salmon to infection by sea lice. The ambient lice infection rates for juvenile chum and pink salmon were up to 32% prevalence, less than one louse per fish and less than two lice per gram (prevalence: 2.0 (1.0) - 32.0 (19.0), mean lice per fish: 0.02 (0.01) - 0.67 (0.22), mean lice per gram: 0.56 (0.08) - 1.93 (0.13)). This result was found to be consistent across geographic areas with no salmon farming activity suggesting that geographic variability was not a significant factor in the natural interaction between sea lice and juvenile salmon. Salmon farms were found to strongly influence the relationship between sea lice and juvenile chum and pink salmon. Sea lice infection rates of juvenile salmon collected near salmon farms were significantly higher than non-salmon farming regions ranging from 3 - 150 times higher in the BA and from 2 - 14 times higher in the Klemtu region. Infection levels near salmon farms were variable in intensity from year to year. The extent to which the sea lice-salmon relationship was affected by salmon farms was dependent on farmed species, farm location, within year variability in fish size, and the scale of salmon farming activities within the region. The results from the laboratory and field studies demonstrate that juvenile chum salmon were more susceptible to infection by sea lice than juvenile pink salmon. However, the exact mechanism for the observed differences was not identified. Possible reasons for the observed differences could be related to genetically determined susceptibility, fish mucous differences, lethal lice infection tolerances. or other factors not examined. The results of this study suggest that the elevated sea lice infection rates observed in the BA and other areas present a significant risk to the health of wild salmon and that salmon farms are the most likely cause based on the biology and ecology of sea lice. In order to better understand the potential for salmon farms to affect wild salmon populations, it is suggested that investigations into farm level sea lice contributions be conducted in the BA and other areas where salmon farms operate. In addition, investigation into the lethal lice infection rates for juvenile salmon at early marine life size should also be conducted.

The edible mud crab, genus Scylla, is important to fisheries and aquaculture throughout the Indo Pacific region, but its taxonomic status has been confused for decades and a new classification has only recently been proposed. This project was undertaken to investigate the species status of mud crabs in Southeast Asia, with a view to deciding whether two sympatric morphs of Scylla found in Ban Don Bay, Surat Thani Province, Thailand, are two separate species. A further aim was to elucidate any possible pre-zygotic reproductive isolating mechanisms (RIMs) and ecological features that maintain the apparent sympatry between these two morphs. Mud crabs were collected from a primary site (Surat Thani, Thailand) as well as from six other locations in Thailand, Vietnam, Malaysia and Bangladesh. Crab samples from the latter sites were used selectively to provide a comparison to the primary study site. Descriptive taxonomy, multivariate morphometrics and allozyme electrophoresis were used to a) determine the number of species present within the crab samples collected; b) to ascertain which species they represent; c) to discover any geographical variation between locations sampled; d) to produce a possible phylogeny that summaries the relationship between Scylla species; and e) to look for pre-zygotic RIMs to explain the sympatry of the two morphs in Surat Thani. Findings from the present study reinforce the recent revision of the taxonomy of the genus Scylla into four species, S. serrata, S. olivacea, S. tranquebarica and S. paramamosain and provides new information on two of the four species which are dominant within Southeast Asia, including Ban Don Bay, Surat Thani Province, S. paramamosain and S. olivacea. Population studies showed both genetic and morphological differentiation between conspecific populations of S. paramamosain and S. olivacea, indicating stock structure for each species, although there is some disparity between morphological and genetic distances for S. paramamosain. This is discussed in relation to the effects of larval dispersal mechanisms and the subsequent recruitment of juvenile crabs. Phylogenetic interpretation of both genetic and morphological characters revealed that both S. serrata and S. olivacea are the most diverged of the four Scylla species; however, the direction of evolution is open to interpretation and the evidence for either S. olivacea or S. serrata as the more primitive species are discussed. Reproductive studies on the two mud crab species found in Surat Thani revealed no physical barrier to hybridization. Both species have a protracted breeding season which continues throughout the year. However, the size at first sexual maturity was significantly smaller for S. olivacea when compared to S. paramamosain. This and other potential mechanisms that may maintain these two species sympatrically are discussed. The clarification of four Scylla species, and the establishment of diagnostic genetic and morphological characters that can be used to identify them, means that research can now focus on both the ecology and life history of these closely related species. Such information is needed urgently with respect to fisheries management as well as to understanding the environmental requirements of each species in order to develop their potential for aquaculture.

This study investigates the reproductive strategies of the pill-box crab, Halicarcinus cookii on the Kaikoura Peninsula, New Zealand. Various aspects essential to understanding reproductive strategies were examined including growth, population dynamics, reproductive biology and mating behaviour. H. cookii exhibits obvious sexual dimorphism such that females develop wide abdomens forming brood chambers, and males tend to grow larger than females and have larger chelipeds in relation to body size. H. cookii allocates energy into growth and reproduction in separate phases of its life cycle where growth ceases as reproductive maturity begins due to a terminal/pubertal moult. Despite the presence of ovigerous females throughout the 15 month sampling period, the population was highly seasonal, with peaks in recruitment and growth occurring primarily during the winter months and peaks in numbers of mature individuals during the summer months. Reproductive output increased with body size in H. cookii, as larger females produced more eggs and larger males transferred more sperm than their smaller counterparts. Ovaries matured prior to the terminal/pubertal moult (anecdysis) and, in multiparous females, in synchrony with brood development, allowing females to produce broods in quick succession, maximising their reproductive output in their short life span (approximately 12-18 months, 6 months as an adult). Incubation duration of broods decreased as seawater temperature increased, suggesting that temperature is the primary cause of the seasonal population cycling. Sperm storage allowed females to produce at least 4 fertilised broods without re-mating. Some sperm mixing in the spermathecae appeared to occur and the ventral-type structure implies last male sperm precedence. Males therefore preferentially mated with females closest to laying a new brood and guarded them longer than other females to ensure their paternity. Guarding duration varied according to the sex ratio allowing males to maximise their reproductive output.

The reproductive strategies of four intertidal grapsid crabs, Hemigrapsus sexdentatus, H. crenulatus, Cyclograpsus lavauxi, and Helice cressa, were studied in the field and laboratory, with emphasis on mating behaviour, duration of female receptivity, and sperm competition. Mating occurred in all species during the intermoult on the days prior to oviposition, when the gonoporo opercula of females became temporarily mobile. Female Helice crassa mated up to three weeks after oviposition, but in all other species mating typically ceased at egg-laying. Male Hemigrapsus pp. used a female-centered competition strategy in which they searched for and defended receptive females until they laid eggs. In contrast, male C. lavauxi searched for and intercepted receptive females only for the duration of copulation and then pursued other receptive females (a mating system termed encounter rate competition with pure search and interception). Male Helice crassa searched for receptive females in their immediate neighbourhood and mated with them briefly on the substrate or in the burrow after which the female left (a mating system termed encounter rate competition with neighbourhoods of dominance). The mating season was short and highly synchronous for Hemigrapsus exdentatus and Cyclograpsus lavauxi and asynchronous for Hemigrapsus crenulatus and Helice crassa. In the laboratory, the mean duration of receptivity for females housed with three males varied between 4.1 and 12.4 days, and the copulation frequency of females varied before oviposition between 2.1 and 24.3 times (mean) depending on the species. Female Hemigrapsus spp. isolated from males stayed receptive significantly longer than females held continuously with males. This suggests that females are able to control the duration of their receptivity, and therefore the time available for mating, according to the absence or presence of males. The operational sex ratio (OSR) had no effect on the duration of female receptivity, but female Hemigrapsus crenulatus mated more often when several males were competing for access. Therefore, male-male competition increased the number of matings per female and hence sperm competition within the female spermathecae. Larger males mated significantly more often than smaller males in all species. However, male size did not affect ejaculate size, meaning that small and large males transferred similar-sized ejaculates, e.g., in Hemigrapsus spp. Males of the two Hemigrapsus species followed a different strategy of sperm allocation. Male H. crenulatus, which are typically confronted with a high mating frequency of the female and a long, asynchronous mating season, distributed similar-sized ejaculates, irrespective of female size. By contrast, male H. sexdentatus, which experience a comparatively lower risk of sperm competition during a short, synchronised mating season, invested larger ejaculates for larger females than for smaller females. In addition, the size of the first and second ejaculates transferred to a female by a male H. crenulatus were not significantly different, whereas the first was larger than the second for H. sexdentatus. A parasitological survey was undertaken of the four grapsid crabs and the presence, seasonal variation and relationship with host gender and size of parasites determined. Four internal parasites were discovered: Nectonema zealandica n. Sp. (Nematomorpha: Nectonematoidea), portunion sp. (Isopoda: Entoniscidae), Profilicollis novaezelandensis n. sp. and profilicollis antarcticus (Acanthocephala: P olymorphidae). Portunion sp. castrated its female hosts, but not the males thereby creating a more male-biased sex ratio. Males parasitised with portunion sp. were equally successful during male-male competition and the number of matings they achieved. The above findings are important for our current understanding of mating strategies in Grapsidae, which are more diverse than previously thought. Females with a restricted duration of sexual receptivity have some control over their receptive period and can therefore influence the OSR and the extent of male-male competition. As females mated multiple times during their receptive period, sperm competition is a common feature in Grapsidae. However, males employed different tactics in regards to sperm competition such as longer mating duration (e.g., C. lavauxi), high number of matings (Helice crassa), or post-copulatory mate guarding until oviposition (Hemigrapsus spp.).

Thesis (M.S.)--University of North Carolina at Wilmington, 2006. / Includes bibliographical references (leaves: 40-42)

Orientador: Rogerio Caetano da Costa / Banca: Marcelo Antonio Amaro Pinheiro / Banca: Alexandre Oliveira de Andrade / Resumo: O crescimento relativo, a maturidade sexual morfológica e funcional, o período reprodutivo, o recrutamento, a razão sexual, o pareamento heterossexual e a fecundidade de Alpheus brasileiro foram investigados. Os camarões foram coletados de março de 2013 a janeiro de 2014, manualmente, na zona intermareal estuarina de Cananéia, SP. Os indivíduos foram identifi4cados em relação ao sexo e mensurados quanto às estruturas: comprimento da carapaça (CC), comprimento do própodo do quelípodo (CPQ), largura do própodo do quelípodo (LPQ), altura do própodo do quelípodo (APQ), comprimento da segunda pleura abdominal (CP), comprimento do apêndice interno (CAI) e comprimento do apêndice masculino (CAM). Foram coletados 186 indivíduos durante o período, sendo 92 machos e 94 fêmeas. As relações que melhor demonstraram mudanças na taxa de crescimento entre jovens e adultos, as quais também utilizadas para estimar a maturidade sexual morfológica para machos e fêmeas, foram CPQ vs. CC e CP vs. CC, com maturidade estimada em 4,70 e 4,77 mm de CC respectivamente. A maturidade funcional encontrada foi 4,80 mm de CC. O período reprodutivo caracterizou-se como sazonal contínuo assim como o recrutamento, mostrando-se uma exceção ao padrão esperado para espécies tropicais e subtropicais. Não houve diferença significativa na razão sexual (M:F) (p > 0,05), provavelmente em função do comportamento de pareamento, no qual ocorre a formação de pares em espécies gonocóricas, favorecendo a distribuição igualitária entre machos e fêmeas. Durante, o estudo 42 pares (macho e fêmea) foram capturados. Os casais estiveram presentes na população em todos os meses estudados. O comportamento territorial é intenso e comumente encontrado nos camarões Alpheidae, portanto, a estratégia de pareamento pode garantir a sobrevivência e o sucesso reprodutivo dos casais. A fecundidade média calculada... / Abstract: The aim of this study was to investigate the relative growth, the morphological and functional sexual maturity, the spawning period, recruitment, sex ratio, heterosexual pairing and fertility of the snapping shrimp Alpheus brasileiro. Shrimps were captured manually from March 2013 to January 2014 in the intertidal estuarine zone of Cananéia, SP. Individuals were identified according to sex and measured in relation to the carapace length (CL), propodus cheliped length (PCL), propodus cheliped width (PQW), propodus cheliped height (PQH), length of second abdominal pleura (PL), internal appendix length (IAL) and male appendage length (MAL). During the studied period, 186 individuals were collected, 92 males and 94 females. The relationships that best evidencied changes in growth rate between juveniles and adults were CPQ vs. CC and CP vs. DC. These relationships were used to estimate the morphological sexual maturity for males and females, which were 4.70 and 4.77 mm CW, respectively. The functional maturity was calculated in 4.80 mm CW. The reproductive period was characterized as seasonal continuous, as well as the recruitment, which is considered as an exception to the expected pattern for tropical and subtropical species. There was no statistically significant difference in sex ratio (M: F) (p> 0.05). This fact is probably due to the pairing behavior, in which the pair formation occurs in gonocoric species and favors equal distribution between males and females. During the study 42 pairs (male and female) were captured. Couples were present in the population in all months of sampling. Territorial behavior is intense and it is commonly found in Alpheidae shrimp, so the pairing strategy can ensure survival and reproductive success. The mean fertility calculated was 148.53 ± 93.37, related to 28 females. There was a positive correlation between the number of eggs and the carapace, Spearman correlation (p<0.05), highlighting a ... / Mestre

Made available in DSpace on 2015-04-09T12:28:07Z (GMT). No. of bitstreams: 0 Previous issue date: 2014-04-25Bitstream added on 2015-04-09T12:48:21Z : No. of bitstreams: 1 000813748.pdf: 2715272 bytes, checksum: e99a9703e86c6286f41d0c2a5bb26d2f (MD5) Bitstreams deleted on 2015-05-06T12:18:27Z: 000813748.pdf,Bitstream added on 2015-05-06T12:19:02Z : No. of bitstreams: 1 000813748_20161231.pdf: 302051 bytes, checksum: 5903b3b7fa65bcd8dc6aed9cf235f681 (MD5) Bitstreams deleted on 2017-01-02T15:03:40Z: 000813748_20161231.pdf,. Added 1 bitstream(s) on 2017-01-02T15:05:04Z : No. of bitstreams: 1 000813748.pdf: 2715274 bytes, checksum: 5dea825016307e60b08697a522a0d120 (MD5) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Projeto Uçá III / O presente estudo avaliou o grau de contaminação da água, sedimento, vegetação arbórea (Rhizophora mangle) e do caranguejo-uçá (Ucides cordatus) por metais, em seis manguezais paulistas, bem como o impacto geno e citotóxico sobre as populações deste crustáceo, com base na frequência de hemócitos (hialinócitos) micronucleados e tempo de retenção do vermelho neutro pelos lisossomos. Os manguezais são áreas de preservação permanente (APPs) e berçários de diversas espécies animais, incluindo o caranguejo-uçá, que é amplamente comercializado e consumido pelo homem em regiões litorâneas. Seis áreas de manguezal do Estado de São Paulo (Cananéia, Iguape, Juréia, Cubatão, São Vicente e Bertioga) foram avaliadas, sendo cada uma representada por três subáreas de amostragem. Amostras de sedimento, folhas da vegetação arbórea (R. mangle), estruturas corpóreas do caranguejo-uçá (U. cordatus) e água da galeria deste crustáceo foram coletadas para a quantificação de seis metais totais (Cd, Cu, Pb, Cr, Mn e Hg), por espectrometria de absorção atômica. As dosagens de metais obtidas foram submetidas à ANOVA, com as médias comparadas por Tukey (5%). Os resultados obtidos quanto ao comportamento dos seis metais totais se coadunam com a literatura especializada, já que o Cd, Pb, Cr e Hg se acumularam mais no sedimento do que nos demais compartimentos abiótico-bióticos analisados, enquanto o Cu e Mn apresentaram maiores concentrações nas estruturas corpóreas de U. cordatus e nas folhas de R. mangle, respectivamente. Considerando a disponibilidade de metais associados à água, sedimento e folhas de R. mangle, os resultados evidenciam que cada área de manguezal (localidade) possui um ou mais metais em maiores proporções relativas, a saber: Cubatão e Bertioga: Pb e Cd; São Vicente: Hg; Juréia: Cr; Iguape: Cu, Mn e Hg; e Cananéia: Mn (em menor escala). Em relação ao acúmulo de metais nas amostras de... / This study evaluated the metals contamination level of water, sediment, woody vegetation (Rhizophora mangle) and the “uçá”-crab (Ucides cordatus) in six mangrove areas located in São Paulo State, as well as the geno cytotoxic impact on the populations of this crustacean, based on micronucleated hemocytes (hyalinocytes) frequency and the retention time of neutral red in their lysosomes. Mangroves are permanent preservation areas (PPAs) and nurseries to several animal species, including the “uçá”-crab, which is widely traded and consumed by humans at coastlands. Six mangrove areas located in São Paulo State (Cananéia, Iguape Juréia, Cubatão, São Vicente and Bertioga) were evaluated, each of them were represented by three replicas. Samples from sediment, leaves of woody vegetation (R. mangle), body structures from “uçá”-crab (U. cordatus) and water from burrows of this crustacean were collected to dosage of six total metals (Cd, Cu, Pb, Cr, Mn and Hg) by atomic absorption spectrophotometer. The metals concentrations were compared by ANOVA and their means by Tukey (at 5%). The results regarding the tendencies of accumulation of six metals are in accordance with the literature, since the Cd, Pb, Cr and Hg have accumulated more in sediment than in others biotic-abiotic compartments analyzed, whereas Cu and Mn have showed higher concentrations in U. cordatus body structures and R. mangle leaves, respectively. At São Paulo mangroves, taking into account the availability of metals associated with their presence in water, sediment and leaves of R. mangle, the results suggest that each area (locality) has one or more metals in larger relative proportions, namely: Cubatão and Bertioga: Pb and Cd; São Vicente: Hg; Juréia: Cr; Iguape: Cu, Mn and Hg; and Cananéia: Mn (smaller scale). About the “uçá”-crab metals accumulation by mangrove area, it were found an association of Cu and Mn in animals from São Vicente and... / FAPESP: 2010/01552-9 / CAPES: 10474-12-9 / FAPESP: 2009/14725-1

Ce travail entre dans le cadre d’une meilleure compréhension des mécanismes de réponse des crustacés au facteur salin. Nos travaux ont démontré que les abondances des copépodes et branchiopodes dans la saline de Sfax sont régulées principalement par les concentrations en sels et la température. Des expérimentations réalisées en laboratoire ont permis de déterminer les salinités optimales pour les trois espèces de copépodes majoritaires (Bryocamptus sp., Oithona nana, Pararcartia grani) et du branchiopode Artemia salina, Une approche biochimique focalisée sur A. salina a montré qu’il assurait son osmorégulation par l’utilisation de l’énergie dépendante de la gestion de ses stocks de protéines, glucides et lipides, et par la mise en œuvre de réponses physiologiques antioxydantes. Une étude exhaustive de la bibliographie a permis de monter que la pompe transmembranaire Na+/K+ ATPase est un élément clé de la gestion de l’osmolarité cellulaire. L’analyse des gènes, ARNm et protéines correspondants à sa sous unité alpha (primordiale pour la fonction) a révélé : i) l’existence d’un gène unique au sein des invertébrés (excepté pour les nématodes), ii) une grande diversité du nombre et de la longueur des introns, iii) un phénomène d’épissage alternatif, et iii) une conservation de domaines protéiques transmembranaires. Enfin, une étude comparative de l’activité de la Na+/K+ ATPase entre deux écrevisses Astacus astacus (espèce native d’Europe) et Procambarus clarkii (espèce invasive en Europe) a démontré que seule l’espèce invasive montrait une activité élevée lors de stress salin ; ce qui pourrait expliquer en partie son aptitude à coloniser des nouveaux milieux. / The aim of our investigations was to increase your understanding of the mechanisms of crustacean’s response to salinity changes. We revealed that, in the Sfax solar saltern, the copepods and branchiopod abundances are mainly regulated by salinity and temperature. Experiments in the laboratory allowed defining the optimum of salinity for the most abundant copepod species (Bryocamptus sp, Oithona nana, Pararcartia grani) and for the branchiopod Artemia salina. An biochemical approach focused on Artemia salina (euryhaline species) showed that he ensured his energy uptake for osmoregulation by the regulation of their internal protein, carbohydrate and lipid contents. In addition, antioxidative reactions are induced to compensate the physiological disruption. A review of bibliography allowed revealing that the transmembrane pump Na+/ K+ ATPase is primordial for the cellular osmolality regulation. The structural analyses of the gene, mRNA and proteins coding alpha subunit in invertebrates showed : i) the existence of a unique gene (except for nematodes), ii) variability in the number and length of introns, iii) an alternative splicing phenomen, and iiii) high conservation of the ten transmembrane protein domains. Finally, a comparative study of the activity Na+/K+ ATPase for two crayfish species (Astacus astacus, native European species; Procambarus clarkia, alien American species) during salt stress demonstrated that only the invasive species have high Na+/K+ ATPase activity; which can explain its ability to colonize various environments.

The thesis summarizes the current knowledge about the class Branchiobdellae including their anatomy, ecology and geographic distribution with respect to the presence of introduced species in Europe. Using samples of Branchiobdellidan obtained from two introduced species of crayfish caught in a pond near Čáslavice u Moravských Budějovic (signal crayfish, Pacifastacus leniusculus) and in Černíský stream (eastern crayfish, Orconectes limosus), two out of seven European species of Branchiobdellidan were identified, namely B. parasita with 100% presence in the eastern crayfish and 58.7% presence in the signal crayfish, and B. pentodonta with 41.3% presence. Based on data collected from the caught crayfish and samples of Branchiobdellidan, the individual weight of eastern crayfish was proved to influence the quantity and biomass of Branchiobdellidan on the body of crayfish (p<0.001), i.e. increased quantity and biomass of Branchiobdellidan was found on more robust specimens of crayfish, however the effect of gender was not statistically significant. With respect to the signal crayfish, a significant difference was observed in the quantity and biomass of Branchiobdellidan depending on the weight of the crayfish (p<0.001), and the influence of the gender of the crayfish was detected (p<0.001), i.e. the quantity and biomass of Branchiobdellidan was higher on the surface of male specimens of crayfish. The presence of eggs in some female signal crayfish had no significant effect on the quantity and biomass of Branchiobdellidan (p=0.052), however in combination with the weight, the influence of the presence or absence of eggs was proved (p=0.011), more robust females showed increased quantity and biomass of Branchiobdellidan.

Several studies have been carried out to understand reproductive biology of invasive crayfish. Many researchers have described how invasive species establish their population in new habitats, interactions between native and invasive species, their fast spreading, changing of behavior and biology especially reproductive behavior and even genetics. But it seems that there are still lots of questions and gaps which need to be addressed in case of invasive crayfish species. This thesis tried to focus on different aspects of reproduction biology of invasive crayfish. Generally, the normal crayfish reproduction mode is gonochorism. But, it has been showed in the literature that a few species such as Cherax quadricarinatus, Samastacus spinifrons, Parastacus virilastacus and Pacifastacus leniusculus may have different reproduction modes such as hermaphroditism or intersex. Parthenogenesis has been found in Procambarus fallax f. virginalis. Also, apomictic parthenogenesis has been reported in Orconectes limosus. Moreover, there have been several manipulations which directly affect reproduction biology of crayfish under lab conditions. Additionally, hybridization can be expected between Astacus astacus and Astacus leptodactylus, Orconectes rusticus and Orconectes propinquus under natural conditions. Some studies supposed that chemical factors also one of the reasons which could lead to some changes in reproductive system of crayfish. The objective of the Chapter 2 was to report first evidence of intersex in the signal crayfish, Pacifastacus leniusculus (Dana, 1852). That specimen appeared morphologically male but with both male and female genital openings, as well. Spermophores were obtained from vas defertia of this speciemen. Histological study was carried out and it has shown that both spermatophores and oocytes were present. The gonadosomatic index showed that intersex male had a GSI three times more higher than normal males. The ultrastructure of spermatozoa in three cambarid species Cambarus robustus, Orconectes propinquus, Orconectes rusticus were described and compered with eight previously studied species from family of Astacidae, Cambaridae and Parastacidae. In the studied cambarids, the crest-like protrusions in the anterior part of the acrosome is one of the most remarkable differences in case of morphological feature in spermatozoa and can be used for distinguishing the members of Cambaridae. The results of biometrical data showed that the smallest and biggest acrosome sizes in the studied species were in Parastacidae and Astacidae, respectively. The duration of post-mating spermatophore storage as well as the timing and temperature of spawning in two crayfish species (Pacifastacus leniusculus and Astacus astacus) were investigated in the Chapter 4. Seventy-one pairs of adult signal crayfish (Pacifastacus leniusculus) and thirty six pairs of noble crayfish (Astacus astacus) were used for experiment. The results indicated that there was a significant difference (P<0.05) between noble crayfish and signal crayfish in average duration of the post-mating spermatophore storage. The duration of the post-mating spermatophore storage is longer in the noble crayfish with 34.6 ? 1.7 days than the signal crayfish with 3.9 ? 0.5 days. There were also differences in the timing of mating and egg laying between the signal crayfish and noble crayfish. In the population of signal crayfish both mating and egg laying overlapped, but in the population of noble crayfish there was at least two weeks gap between last mating and first egg laying individuals. Water temperature was significantly (P<0.05) higher during mating and egg laying in the signal crayfish than the noble crayfish. The average temperatures for mating in both species were significantly (P<0.05) higher than the temperatures that they utilized for egg laying. As a conclusion more research is needed for better understand of the reproduction strategies in invasive crayfish.