The noble crayfish (Astacus astacus) is critically endangered in Sweden. This is mainly due to the crayfish plague (Aphanomyces astaci), a lethal disease that, among other things, can be spread through the stocking of fish from contaminated water or contaminated fishing gear. The largest single propagation path is the illegal introduction of infected signal crayfish (Pacifastacus leniusculus). A conservation measure for crayfish is to re-introduce it to where it has a chance to survive, though a sustainable, locally regulated fishing can also serve as an indirect protection for the species. When the local inhabitants are allowed to keep their fishing culture and when fishing is acceptable, the incentive for illegal stocking of signal crayfish is low. However, it is important to avoid overfishing because the recovery, especially in the northern regions, can take several years. Therefore, it is important to know how crayfish respond long-term to fishing and environmental factors. Crayfish populations became extinct in the River Ljungan for unknown reasons in 1999. The water flow of the river has been used for activities such as fishing, timber transport and hydroelectric power since the 1500s, and the noble crayfish has been part of the fauna since the last century. The River Ljungan was known as one of Sweden's best fishing areas for crayfish and fishing became an important part of the local tradition. When the crayfish populations became extinct, a reintroduction program was a natural step, and crayfish are nowadays re-established in the river. From 1963 to 1990 the Swedish Board of Fisheries collected data from crayfish fishing in the River Ljungan to determine the economic damage to fishery owners caused by the construction of a power plant. After each season the fishermen reported the catch. In this thesis, the data was used to investigate which factors influence the long-term size of the crayfish catch and how the crayfish catches were affected by the power plant building. After re-introduction of the crayfish to the River Ljungan, the local fishermen monitored the population development in a simple, standardized way. To examine the validity of their measurements and to investigate the body growth of the individuals, a capture-recapture technique with a permanent marking of the crayfish was used. The crayfish catches were primarily impacted by the previous years' catch size, and a large catch the previous year resulted in a reduced catch the following year. A mild winter climate (NAO-index > -0.7) six years before the catch implied a large catch, whereas a high water flow during the autumn or spring (>95m3s-1) two years before the catch, implied a poor catch. Major habitat changes in the form of greatly reduced water flow (~90%) were negative for crayfish catches. The standardized method of fishing used by the local fishermen to monitor the development of the crayfish population was precise enough to detect population trends and this method can therefore be recommended to monitor future re-introductions of crayfish. Although the River Ljungan is located at the northern edge of the species' range, noble crayfish in the river presently have a body growth rate that is close to the maximum measured for crayfish (8 mm/moult for females and 10 mm/moult for males). Based on the results, the most important advice for sustainable fisheries in Ljungan and other northern rivers is to: Monitor the population trends, NAO-index and water flow in May and October.  Use the results from the monitoring to determine the number of allowed fishing days and traps. Collect data about the catch size and efforts from legal fishing and use it to evaluate the sustainability of the fishing. Enhance the buildup of the harvestable cohort by -saving reproductive females -introduce a size limit of 10 cm -provide proper shelters for the non-harvestable cohort. / Flodkräftan (Astacus astacus) är akut hotad i Sverige främst på grund av kräftpest (Aphanomyces astaci). Kräftpest är en dödlig sjukdom som bland annat kan spridas vid fiskutsättningar från smittade vatten eller med smittade fiskeredskap. Den enskilt största spridningsvägen är illegala introduktioner av smittade signalkräftor (Pacifastacus leniusculus). En bevarandeåtgärd för flodkräfta är att återintroducera den till lokaler där den har chans att överleva, men ett hållbart fiske med lokal styrning kan också fungera som ett indirekt skydd för arten. När lokalbefolkning tillåts att behålla sin fiskekultur och fisket är bra, blir incitamentet för illegal inplantering av signalkräfta lågt. Men det är viktigt att undvika överfiske då återhämtning, speciellt i nordlig miljö kan ta åtskilliga år. Därför är det betydelsefullt att veta hur flodkräftan svarar på fiske och omgivningsfaktorer i det långa loppet. Flodkräftbeståndet dog, av okänd anledning, ut i Ljungan 1999. I Ljungans flöde har det fiskats, flottats timmer och utvunnits vattenkraft etc. sedan 1600-talet och under det senaste århundradet har flodkräftan varit en del av Ljungans fauna. På sin tid var det en av Sveriges bästa lokaler för flodkräfta. Kräftfisket blev en viktig del av den lokala traditionen, så när kräftbeståndet dog ut var återintroduktion en självklarhet och flodkräftan har åter sin hemvist i älven. Under perioden 1963 till och med 1990 samlade Fiskeriverket in data från kräftfisket i Ljungan för att fastställa den ekonomiska skadan som fiskerättsägarna åsamkats i samband med ett kraftverksbygge. Efter varje säsong fick fiskarna rapportera hur fisket gått. I den här avhandlingen, har det materialet använts för att undersöka vilka faktorer som påverkar kräftfångstens storlek på lång sikt och hur kräftfångsterna påverkades av kraftverksutbyggnaden. Efter återintroduktionen av flodkräfta till Ljungan mättes beståndsutvecklingen på ett enkelt, men standardiserat sätt av de lokala fiskevårdsområdena. För att undersöka validiteten av deras mätningar och hur kräftornas individuella utveckling fortskred, användes fångst- och återfångstteknik, med permanent märkning av kräftorna. Kräftfångsternas storlek påverkades främst av tidigare års fångststorlek; en stor fångst föregående år innebar minskad fångst följande år. Ett milt vinterklimat (NAO-index > -0.7) sex år före fångst innebar bättre fångster, medan höga vattenflöden höst och vår (>95m3s-1) två år före fångsttillfället innebar sämre fångst. Större habitatförändringar i form av kraftigt reducerade vattenflöden (~90%) var negativt för kräftfångsterna. Den standardiserade metoden som fiskevårdsområdena använt för att mäta beståndsutvecklingen var tillräckligt precis för att påvisa populationsutvecklingen och kan därför rekommenderas också för uppföljning av andra återintroduktioner av flodkräfta. Trots att Ljungan ligger i norra kanten av flodkräftans utbredningsområde har flodkräftorna i Ljungan för närvarande en kroppstillväxt som är nära den maximala som uppmätts för flodkräfta (8 mm/ömsning för honor och 10 mm/ömsning för hannar). Utifrån resultaten är de viktigaste råden för ett hållbart fiske i Ljungan och andra nordliga vattendrag att: Övervaka kräftstammens utveckling, NAO-index samt vattenflöde i maj och oktober.  Använda resultaten från övervakningen för att bestämma antalet tillåtna fiskedagar och burar. Samla in data om fångststorlek och hur många burnätter som faktiskt gjordes under säsongen. Använda data för att utvärdera fiskets hållbarhet. Stärka uppbyggnaden av den fångstbara storleken genom att -spara reproduktiva honor -införa en storleksgräns på 10 cm -tillse att det finns gömslen för kräftor av icke-fångstbar storlek.

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 aim of this study was to investigate effects of the triazine herbicide metribuzine on oxidative stress level and antioxidant enzymes activity in gills, muscle and hepatopancreas of signal crayfish (Pacifastacus leniusculus Dana) and also extension of knowledge about effect of metribuzine on the environment. The experiment took up 60 days. Crayfish were exposured to metribuzine concentrations of 0.52 micrograms.l-1 (real environmental concentration) and 3.06 mg.l-1 (10% 96hLC50) for the first 30 days. Then a second phase followed depuration without metribuzine (30 days). Changes in the oxidative stress level (TBARS), superoxiddismutase (SOD) activity and catalase (CAT) activity were observed in all examined tissues. Changes in glutathionreductase (GR) activity were observed only in hepatopancreas. Chronic exposure of metribuzine demonstrated an oxidative damage of cell lipids, proteins and also changes in antioxidant activity in examined crayfish tissues.The results of this study suggest that crayfish are a very suitable organisms for toxicological tests and simultaneously extend knowledge about effect of metribuzine on the environment.

The spread of non-native species is a global threat and the rate at which biological invasions occur is likely to increase in the future. This thesis examines the implications of the invasive signal crayfish, Pacifastacus leniusculus (Dana), for instream communities and abiotic processes within lowland rivers in England. The potential effects on lotic macroinvertebrate communities and fine sediment dynamics are investigated at a range of spatial and temporal scales, from the examination of national long-term datasets through to short-term detailed mesocosm experiments. Interrogation of macroinvertebrate community data from three English regions was undertaken to understand the temporal and spatial extent of signal crayfish effects. Invasive crayfish had significant long-term and persistent effects on resident macroinvertebrate communities regardless of the lithology or other environmental characteristics of the region. The resultant modifications to community composition had repercussions for several widely employed freshwater biomonitoring tools which employ faunal abundance in their derivation. A reach-scale field study was undertaken at two sites, one invaded by crayfish and one which did not support populations of crayfish (control), to assess the potential contribution of signal crayfish for fine sediment dynamics (ingress, fluxes and ultimately the overall implications for sediment budgets). Reach-scale field experiments examining the effect of crayfish invasion on resident macroinvertebrate communities over a 126-day period indicated that once crayfish populations are well-established their effects are persistent. However, separating the effects of crayfish from wider macroinvertebrate community dynamics and life-history characteristics of the invader and resident taxa means that attributing the effects is far from clear. The thesis presents the results of a series of novel mesocosm experiments which examined the dynamic and two-way interactions of predator-prey relationships and potential zoogeomorphological effects of signal crayfish and the freshwater shrimp, Gammarus pulex. Signal crayfish had a significant effect on the mass of fine sediment infiltrating into the gravel matrix associated with foraging and predatory activity; however this was strongly controlled by prey availability. Finally, through the development of conceptual models, the thesis illustrates the need for greater integration of ecological and geomorphological theories, at relevant environmental scales (temporal and spatial) to achieve truly interdisciplinary research.

Os lagostins são crustáceos decápodos límnicos que podem ser encontrados em água corrente, outros preferem água com pouca ou nenhuma corrente, como pequenos riachos, lagos, reservatórios e pântanos. Muitas espécies vivem em galerias subterrâneas com níveis mais baixos de oxigênio; assim, estas espécies podem mostrar adaptações metabólicas às condições hipóxicas. O objetivo desta pesquisa foi comparar o metabolismo de duas espécies de lagostins com diferentes hábitos, Parastacus defossus e Parastacus brasiliensis. P. defossus é uma espécie fossorial, vive em galerias com baixos níveis de oxigênio e P. brasiliensis é encontrado em ambientes lóticos com maiores níveis de oxigênio. Amostragens sazonais foram realizadas da primavera de 2006 ao inverno de 2007 para determinações metabólicas sazonais e posteriormente, amostragens foram realizadas durante o inverno de 2008 para análises metabólicas dos animais submetidos à hipóxia e recuperação pós-hipóxia. P. brasiliensis foi amostrado em Mariana Pimentel, Rio Grande do Sul (Brasil) e P. defossus foi amostrado no Lami, Porto Alegre, Rio Grande do Sul (Brasil). Nos experimentos de hipóxia, grupos de animais foram submetidos à hipóxia por 1, 2, 4 e 8 horas. Períodos de recuperação póshipóxia também foram analisados, após 4 hs de hipóxia, grupos de animais foram colocados em aquários com água aerada e foram removidos em intervalos de 1, 3, 6 e 9 hs. Após esse período foram extraídas amostras de hemolinfa e removidos o hepatopâncreas, o músculo, as brânquias e as gônadas para a determinação de glicose, lactato, glicose livre, glicogênio, proteínas totais, lipídios totais, colesterol total, arginina e arginina fosfato. Os resultados das análises sazonais mostraram diferentes respostas entre as estações do ano e entre as espécies, para todos os parâmetros metabólicos, com exceção das proteínas nas brânquias e do lactato na hemolinfa. As variações metabólicas em P. defossus foram principalmente relacionadas com o período reprodutivo e os períodos de baixa concentração de oxigênio nas galerias, enquanto os resultados em P. brasiliensis sugerem uma alocação significativa dos nutrientes da dieta para o tecido gonadal durante o período reprodutivo, com uma menor transferência das reservas de diferentes tecidos para as gônadas. Em relação ao metabolismo dos animais submetidos à hipóxia foi observado que em ambas as espécies, os níveis de glicose e de lactato aumentaram significativamente em hipóxia. Reduções de glicogênio, lipídios e colesterol foram registradas no hepatopâncreas e no tecido muscular, especialmente de P. defossus. Todos os tecidos de P. defossus e P. brasiliensis mostraram reduções nos níveis de glicose livre, mas essas reduções não foram significativas. Todas as reservas das brânquias anteriores e posteriores, com exceção das reservas de glicogênio, mostraram comportamento semelhante em ambas as espécies. As duas espécies de Parastacus armazenaram e utilizaram arginina fosfato, principalmente P. defossus. Entre os resultados do metabolismo dos animais submetidos à recuperação pós-hipóxia foram observadas que a restauração dos níveis de lactato foi mais rápido em P. defossus quando comparado com P. brasiliensis. Essa espécie restabeleceu suas reservas de glicogênio do hepatopâncreas e do tecido muscular. Já os níveis de glicose livre foram rapidamente restabelecidos em todos os tecidos das duas espécies. Em relação às reservas de arginina fosfato, P. defossus mostrou maiores concentrações que P. brasiliensis. As duas espécies mostraram capacidade de restaurar os níveis de arginina fosfato, mas também utilizaram essas reservas durante períodos de recuperação. Nas espécies, as reservas de lipídios totais e colesterol parecem ser uma importante fonte de energia durante a recuperação. / Some species of crayfish live in flowing water, and others prefer water with little or no current such as small streams, lakes, reservoirs, and swamps. Many species live in subterranean burrows with lower oxygen levels, and can show metabolic adaptations to hypoxic conditions. The aim of this study was to compare the metabolism of two crayfish species with different habitats, Parastacus defossus and Parastacus brasiliensis. P. defossus is fossorial, living in burrows with low oxygen levels, and P. brasiliensis lives in lotic environments with higher oxygen levels. Seasonal sampling was conducted from spring 2006 to winter 2007 for seasonal metabolic determinations, and samples were taken during the winter of 2008 for metabolic analyses of the animals subjected to hypoxia and during the post-hypoxia recovery. P. brasiliensis was collected in Mariana Pimentel, Rio Grande do Sul (Brazil) and P. defossus at Lami, Porto Alegre, Rio Grande do Sul. In the hypoxia experiments, groups of animals were subjected to hypoxia for 1, 2, 4, and 8 h. Periods of post-hypoxia recovery were also analyzed; after 4 h of hypoxia, groups of animals were placed in tanks with oxygenated water and were then removed at intervals of 1, 3, 6, and 9 h. The hemolymph was extracted, and the hepatopancreas, muscle, gills, and gonads were removed for determination of glucose, lactate, free glucose, glycogen, total proteins, total lipids, total cholesterol, arginine, and arginine phosphate. The results of the seasonal analysis showed, for all metabolic parameters, different seasonal responses between the species, with the exception of proteins in gills, and of lactate in hemolymph. The metabolic variations in P. defossus were mainly related to reproductive period and periods of low oxygen concentration in the burrows. The results for P. brasiliensis suggested a significant allocation of dietary nutrients to gonadal tissue during the reproductive period, with a smaller transfer of reserves from different tissues to gonads. In both species, glucose and lactate levels increased significantly in hypoxia. Reductions of glycogen, lipids, and cholesterol were recorded in hepatopancreas and muscle tissue, especially of P. defossus. In all tissues of P. defossus and P. brasiliensis were observed reductions in the free glucose levels, but these reductions weren’t significant. All reserves in the anterior and posterior gills, except glycogen, behaved similarly in both species. Both Parastacus species, mainly P. defossus, stored and used arginine phosphate. During post-hypoxia recovery, lactate was restored more rapidly in P. defossus than in P. brasiliensis. P. defossus restored its glycogen reserves in the hepatopancreas and muscle tissue. Free glucose was quickly restored in all tissues of both species. In relation to the reserves of arginine phosphate, P. defossus showed higher concentrations than P. brasiliensis. The two species showed ability to restore this metabolite, but they also used this metabolite during longer periods of recovery. In both species, the reserves of total lipids and cholesterol seemed be an important source of energy during the recovery period.

Os lagostins são crustáceos decápodos límnicos que podem ser encontrados em água corrente, outros preferem água com pouca ou nenhuma corrente, como pequenos riachos, lagos, reservatórios e pântanos. Muitas espécies vivem em galerias subterrâneas com níveis mais baixos de oxigênio; assim, estas espécies podem mostrar adaptações metabólicas às condições hipóxicas. O objetivo desta pesquisa foi comparar o metabolismo de duas espécies de lagostins com diferentes hábitos, Parastacus defossus e Parastacus brasiliensis. P. defossus é uma espécie fossorial, vive em galerias com baixos níveis de oxigênio e P. brasiliensis é encontrado em ambientes lóticos com maiores níveis de oxigênio. Amostragens sazonais foram realizadas da primavera de 2006 ao inverno de 2007 para determinações metabólicas sazonais e posteriormente, amostragens foram realizadas durante o inverno de 2008 para análises metabólicas dos animais submetidos à hipóxia e recuperação pós-hipóxia. P. brasiliensis foi amostrado em Mariana Pimentel, Rio Grande do Sul (Brasil) e P. defossus foi amostrado no Lami, Porto Alegre, Rio Grande do Sul (Brasil). Nos experimentos de hipóxia, grupos de animais foram submetidos à hipóxia por 1, 2, 4 e 8 horas. Períodos de recuperação póshipóxia também foram analisados, após 4 hs de hipóxia, grupos de animais foram colocados em aquários com água aerada e foram removidos em intervalos de 1, 3, 6 e 9 hs. Após esse período foram extraídas amostras de hemolinfa e removidos o hepatopâncreas, o músculo, as brânquias e as gônadas para a determinação de glicose, lactato, glicose livre, glicogênio, proteínas totais, lipídios totais, colesterol total, arginina e arginina fosfato. Os resultados das análises sazonais mostraram diferentes respostas entre as estações do ano e entre as espécies, para todos os parâmetros metabólicos, com exceção das proteínas nas brânquias e do lactato na hemolinfa. As variações metabólicas em P. defossus foram principalmente relacionadas com o período reprodutivo e os períodos de baixa concentração de oxigênio nas galerias, enquanto os resultados em P. brasiliensis sugerem uma alocação significativa dos nutrientes da dieta para o tecido gonadal durante o período reprodutivo, com uma menor transferência das reservas de diferentes tecidos para as gônadas. Em relação ao metabolismo dos animais submetidos à hipóxia foi observado que em ambas as espécies, os níveis de glicose e de lactato aumentaram significativamente em hipóxia. Reduções de glicogênio, lipídios e colesterol foram registradas no hepatopâncreas e no tecido muscular, especialmente de P. defossus. Todos os tecidos de P. defossus e P. brasiliensis mostraram reduções nos níveis de glicose livre, mas essas reduções não foram significativas. Todas as reservas das brânquias anteriores e posteriores, com exceção das reservas de glicogênio, mostraram comportamento semelhante em ambas as espécies. As duas espécies de Parastacus armazenaram e utilizaram arginina fosfato, principalmente P. defossus. Entre os resultados do metabolismo dos animais submetidos à recuperação pós-hipóxia foram observadas que a restauração dos níveis de lactato foi mais rápido em P. defossus quando comparado com P. brasiliensis. Essa espécie restabeleceu suas reservas de glicogênio do hepatopâncreas e do tecido muscular. Já os níveis de glicose livre foram rapidamente restabelecidos em todos os tecidos das duas espécies. Em relação às reservas de arginina fosfato, P. defossus mostrou maiores concentrações que P. brasiliensis. As duas espécies mostraram capacidade de restaurar os níveis de arginina fosfato, mas também utilizaram essas reservas durante períodos de recuperação. Nas espécies, as reservas de lipídios totais e colesterol parecem ser uma importante fonte de energia durante a recuperação. / Some species of crayfish live in flowing water, and others prefer water with little or no current such as small streams, lakes, reservoirs, and swamps. Many species live in subterranean burrows with lower oxygen levels, and can show metabolic adaptations to hypoxic conditions. The aim of this study was to compare the metabolism of two crayfish species with different habitats, Parastacus defossus and Parastacus brasiliensis. P. defossus is fossorial, living in burrows with low oxygen levels, and P. brasiliensis lives in lotic environments with higher oxygen levels. Seasonal sampling was conducted from spring 2006 to winter 2007 for seasonal metabolic determinations, and samples were taken during the winter of 2008 for metabolic analyses of the animals subjected to hypoxia and during the post-hypoxia recovery. P. brasiliensis was collected in Mariana Pimentel, Rio Grande do Sul (Brazil) and P. defossus at Lami, Porto Alegre, Rio Grande do Sul. In the hypoxia experiments, groups of animals were subjected to hypoxia for 1, 2, 4, and 8 h. Periods of post-hypoxia recovery were also analyzed; after 4 h of hypoxia, groups of animals were placed in tanks with oxygenated water and were then removed at intervals of 1, 3, 6, and 9 h. The hemolymph was extracted, and the hepatopancreas, muscle, gills, and gonads were removed for determination of glucose, lactate, free glucose, glycogen, total proteins, total lipids, total cholesterol, arginine, and arginine phosphate. The results of the seasonal analysis showed, for all metabolic parameters, different seasonal responses between the species, with the exception of proteins in gills, and of lactate in hemolymph. The metabolic variations in P. defossus were mainly related to reproductive period and periods of low oxygen concentration in the burrows. The results for P. brasiliensis suggested a significant allocation of dietary nutrients to gonadal tissue during the reproductive period, with a smaller transfer of reserves from different tissues to gonads. In both species, glucose and lactate levels increased significantly in hypoxia. Reductions of glycogen, lipids, and cholesterol were recorded in hepatopancreas and muscle tissue, especially of P. defossus. In all tissues of P. defossus and P. brasiliensis were observed reductions in the free glucose levels, but these reductions weren’t significant. All reserves in the anterior and posterior gills, except glycogen, behaved similarly in both species. Both Parastacus species, mainly P. defossus, stored and used arginine phosphate. During post-hypoxia recovery, lactate was restored more rapidly in P. defossus than in P. brasiliensis. P. defossus restored its glycogen reserves in the hepatopancreas and muscle tissue. Free glucose was quickly restored in all tissues of both species. In relation to the reserves of arginine phosphate, P. defossus showed higher concentrations than P. brasiliensis. The two species showed ability to restore this metabolite, but they also used this metabolite during longer periods of recovery. In both species, the reserves of total lipids and cholesterol seemed be an important source of energy during the recovery period.

The diploma thesis observed the indicators of growth in individual developmental stages of our native crayfish (Astacus astacus, Austropotamobius torrentium, Astacus leptodactylus) and non-native crayfish (Pacifastacus leniusculus, Orconectes limosus) under experimental conditions. The next aim of work was to describe the time of hatching of these species, the moulting interval, the frequency of moulting and increase after individual moulting during the first vegetation season in two different temperatures (15{$\rm^o$}C a 21{$\rm^o$}C).

Main purpose of this diploma work was to find out possibility using PIT telemetry in monitoring strange crayfish species Spinycheek crayfish Orconectes Limosus. Research of the theme consisted of three steps: two laboratory researches and one research in the natural environment. The first laboratory study concerned tagging passive integrated transponder (PIT) to various part of crayfish body. PIT tags were internally implanted to cephalothorax, abdomen and claw. The highest mortality was in tagging to claw. The second laboratory research consisted of comparing different tagging methods to PIT telemetry. Crayfish were tagging by PIT telemetry, soldering, visible implant elastomers and visible implant Alpha tags. Among tagging groups there were not to find out different in mortality. In the third research the crayfish were tagging in their natural environment. There were using three methods: PIT telemetry, soldering and VI Alpha tags. This experiment wasn´t successful. During recapturing crayfish there were not to find any tagging crayfish.

The freshwater crayfish, Pacifastacus leniusculus, has been used as a model for studying hematopoiesis or blood cell production or hematopoiesis and immunity. The work of this thesis aims to investigate the impact of factors such as ROS signaling, Ast1, and the PVF/PVR signaling pathway in controlling stem cell behavior during hematopoiesis and specifically the role of the crosslinking enzyme transglutaminase (TGase) in regulation of hematopoiesis. The role of ROS in crayfish hematopoiesis was characterized by using the antioxidant named NAC to inhibit ROS production. Low ROS level resulted in a prolonged decrease in hemocyte numbers and a combined injection of LPS and NAC caused a slower rate of new hemocyte production. A low ROS level in cell cultures supplemented with crude Ast1 was found to inhibit cell spreading and a high extracellular TGase activity was detected on the surfaces of APC and HPT cells. We suggest that ROS serves as a prime signal to control proliferation and differentiation of progenitor cells by affecting extracellular TGase activity. We reported an inhibitory effect of Ast1 on TGase enzyme activity and on its crosslinking activity and consequently Ast1 affects the clot formation and thus coagulation by inhibiting the crosslinking activity of the TGase enzyme. Secretion of the clot protein (CP) and the production of CP filament network between spreading cells were observed in HPT cell cultures in vitro. In the presence of CP together with Ast1 in 3D-collagen-I cultures, HPT cells were found to be more elongated and they formed chains of cells throughout the surrounding matrix. In the HPT tissue, CP was located around the HPT cells or around the lobules of HPT, and thus, CP was demonstrated to be a part of ECM and to possibly function together with collagen in generating a suitable environment for HPT progenitor cells. The inhibition of PVF/PVR downstream signaling pathway by Sunitinib malate resulted in a dramatic change of cell morphology and induction of an increase cell surface area during cell culture. The addition of crude Ast1 into the cell cultures in vitro enhanced this effect. Consequently, cell migration was stimulated and a high extracellular TGase activity on HPT cell surface was found after this inhibition. In conclusion, the work in this thesis provides new insight in understanding the role of the extracellular matrix (ECM) and extracellular TGase activity in controlling stem cell activity.

Neurogenesis primarily occurs during embryonic development in decapod crustaceans, ending when the embryonic precursor cells die. However, areas in the central olfactory pathway are exceptions to this. Here, neurons are produced throughout the animal’s life from precursor cells in the neurogenic niche. Cells within the niche divide and migrate to clusters in the olfactory pathway where they eventually differentiate into neurons. The number of cells in the niche correlates with the total number of hemocytes, which have been suggested to be a source of adult-born neurons. Hemocytes are further an important part of the innate immunity since containing the compounds of the proPO-system needed for the melanization reaction. The purpose of this study was to find out whether the melanization reaction matters when it comes to neural injuries. Neural injury was induced by cutting of the first pair of antennae, where neurons are connected to the olfactory pathway. Hemocytes in the hemolymph were counted and characterized and phenoloxidase activity in the brain was measured before and after neural injury. mRNA expression was measured for prophenoloxidase, the neurogenic niche marker glutamine synthetase 2 as well as for astakine 1. Astakine 1 protein had been found in increased levels after neural injury in previous studies. Significant differences were detected for number of hemocytes in injured crayfish and for glutamine synthetase 2 and prophenoloxidase in control crayfish. However, these findings did not provide strong enough evidence to suggest that the melanization reaction plays a role after neural injury. More research is still needed, perhaps by studying the distribution of hemocytes in the brain at different times post-injury by histological sectioning.