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Gladman, Zara F. "Crayfish in Scotland." Thesis, University of Glasgow, 2012. http://theses.gla.ac.uk/3977/.
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Unlike the rest of Britain, Scotland has no native crayfish species. There are, however, two introduced species: the white-clawed crayfish (Austropotamobius pallipes) has inhabited Loch Croispol in Sutherland and Whitemoss Reservoir in Renfrewshire for several decades. A. pallipes is endangered in its native range and Scottish stocks may constitute an important conservation resource in the future. The other crayfish species in Scotland, the North American signal crayfish (Pacifastacus leniusculus) was first recorded in the wild in 1995 and has spread rapidly to inhabit many river catchments and standing waters, where it is considered a serious threat to native biodiversity. The purpose of this thesis was to conduct research into the distribution, control and impact of non-native crayfish in Scotland, with a main focus on P. leniusculus. A comparative field study on the River Clyde in southern-central Scotland was used to test the efficacy of different sampling methods for detecting P. leniusculus in shallow, flowing waters. A combination of kick-sampling and three-run electrofishing was shown to be the most effective method and assisted in the development of a crayfish detection protocol. This protocol has been applied by fishery trusts across Scotland to determine the fine-scale distribution of P. leniusculus in rivers. Results of a radio-tracking study in the River Clyde catchment showed that P. leniusculus moves up to 195 m day -1 in lotic habitats, with flow and in-stream barriers identified as potential impediments to movement. In addition to studies of P. leniusculus, surveys were undertaken to assess the status of the two A. pallipes populations in Scotland. Results showed the occurrence of a low density and high density population at Loch Croispol and Whitemoss Reservoir respectively. These sites could serve as long-term “ex-situ” ark sites for A. pallipes but only if measures are taken to mitigate the current biosecurity threats of P. leniusculus and disease. Laboratory studies were used to assess the potential threat of P. leniusculus to Atlantic salmon (Salmo salar) redds and the globally endangered freshwater pearl mussel (Margaritifera margaritifera). The burial of Salmo salar eggs in redds appears to afford protection from predation by P. leniusculus but other life stages may be at greater risk. Crayfish attempted to predate upon M. margaritifera but were unsuccessful, probably due to the thick, protective shell of the adult mussels tested; predation of juvenile mussels is predicted to be more likely. Finally, the impact of a large-scale trapping programme on a population of P. leniusculus in a large lake was evaluated using mark and recapture methods at Loch Ken in southern Scotland. The programme significantly reduced the number of males in the population but its effect on females was complicated by seasonal variation in trappability and the bias of traps towards males. Depth was found to be a significant determinant of the catch of P. leniusculus. Animals were also found to make significant movements of 800 metres in two weeks. Crayfish occur in Loch Ken at densities which are high compared with other lakes and the loss of native biodiversity there is expected to be considerable. Continued research into invasive species such as P. leniusculus will provide valuable data to support management decisions and help tackle what is one of the top five drivers of human-induced global change.
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Beatty, Stephen John. "Translocations of freshwater crayfish : contributions from life histories, trophic relations and diseases of three species in Western Australia /." Access via Murdoch University Digital Theses project, 2005. https://wwwlib.murdoch.edu.au/adt/browse/view/adt-MU20050718.152608.
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Studer, Thomas. "Smelling out the competition: Response behavior of naive crayfish to novel crayfish odors." Bowling Green State University / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1401464496.
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Wong, Frank Yet Kheong. "Study of non-halophilic Vibrio in Australian freshwater crayfish farms : distribution, epidemiology and virulence /." [St. Lucia, Qld. : s.n.], 2001. http://www.library.uq.edu.au/pdfserve.php?image=thesisabs/absthe16642.pdf.
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Allen, Sarah Kathryn. "Flow Cytometric Analysis of Crayfish Hemocytes." Digital Commons @ East Tennessee State University, 2011. https://dc.etsu.edu/etd/1309.
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Crayfish exhibit innate immune responses via hemocytes and their products. There are 3 hemocyte populations: hyaline cells, granular cells, and semigranular cells. Hemocytes from laboratory housed, untreated crayfish (normal crayfish) have been quantified on the basis of cell type, cell size, and cell granularity using Flow Cytometry. These data present the first overall picture of normal hemocytes from Red Swamp Crayfish with regard to cell type, cell size, and cell granularity and will serve as a baseline for all future studies in our lab. Experiments using crayfish injected with Pseudomonas aeruginosa, Staphylococcus aureus, or crayfish saline alone showed significant and consistent changes in cell type in cells from crayfish injected with bacteria with a decrease in hyaline cells and an increase in granular cells. This effect was greater in crayfish injected with Gram - bacteria. In addition, crayfish injected with Pseudomonas aeruginosa showed a significant difference in Granular cell size with a shift to larger cells and a significant decrease in granularity in the Granular cell population. Cells from crayfish treated with Staphylococcus aureus did not show these changes.
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Harlioğlu, Muzaffer Mustafa. "Comparative biology of the signal crayfish, Pacifastacus leniusculus (Dana), and the narrow-clawed crayfish, Astacus leptodactylus Eschscholtz." Thesis, University of Nottingham, 1996. http://eprints.nottingham.ac.uk/13339/.
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Some aspects of the biology of Pacifastacus leniusculus and Astacus leptodactylus have been compared. The literature survey shows that considerably more studies have been carried out on P. leniusculus than A. leptodactylus. Although no major differences have been found in the morphology of appendages and mouthparts of the species, structural differences have been found in the abundance of setae on the second maxilliped, in the number of teeth on the mandibles and the crista dentata, and form of the chelipeds. Studies on the environmental tolerance of the species show that both species are able to survive in saline water for long periods of time but they can only increase in number in low salinities. Both species can survive over a wide range of temperatures, but they cannot tolerate temperatures of 34 °C after stepwise acclimation. Although the results do not show a clear difference in the tolerance of P. leniusculus and A. leptodactylus to low oxygen, there are some indications that A. leptodactylus is more tolerant of decreased oxygen tensions than P. leniusculus. By using a non-invasive heart beat monitor on crayfish it has been observed that the frequency of heart beats is extremely variable and can be affected by many factors, such as temperature and salinity. Juveniles of the two species can have a significant impact on plant and macroinvertebrate communities. The results also show that both species can have a negative effect on the recruitment of fish populations in freshwaters by eating fish eggs. Competition experiments show that both juveniles and adults of P. leniusculus are significantly more aggressive than those of A. leptodactylus. The results also show that A. leptodactylus would be eliminated by P. leniusculus if they met in a wild. Adults of the species prey on their juveniles, except the brooding females with stage 2s. This predation occurs in the presence of adequate nutrition. Non-predatory behaviour of the brooding females may indicate the presence of pheromones in the species. Reproductive efficiency of the populations of the species in Britain is as good as any studied elsewhere. In comparison to A. leptodactylus, P. leniusculus has more eggs, but smaller in size. Pleopodal egg development of the species can be reduced from seven months to three months with temperature acclimation, but photoperiod is not a factor in reducing pleopodal egg development. In both species sexual dimorphism was observed between males and females. Males of both species and females of P. leniusculus exhibit allometric or isometric growth during their lives but female A. leptodactylus exhibits isometric growth throughout. Comparison of body parameters shows that P. leniusculus can be considered as a morphologically better species to adapt to environmental conditions than A. leptodactylus because it has large and heavy chelae, and heavy body weight. Both species grow fast, but because P. leniusculus hatches earlier it has an advantage over A. leptodactylus and has bigger juveniles by the end of the first summer. In both species males produce significantly more claw meat than females. Although A. leptodactylus produces significantly more tail meat, males of P. leniusculus produce significantly more claw and total meat. Significant differences occur in the tail meat yield of female A. leptodactylus and in the claw meat yield of female P. leniusculus, but males produce similar amount of meat in winter and summer. The Swedish trappy is very effective method of catching both species over a certain size. Day and night catches show that both species are very active during the day and night.
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Herleth-King, Shawna S. "Habitat use of two crayfishes, Orconectes meeki meeki and Orconectes williamsi, in a small Missouri Ozark stream a thesis presented to the faculty of the Graduate School, Tennessee Technological University /." Click to access online, 2009. http://proquest.umi.com/pqdweb?index=25&did=1908035801&SrchMode=1&sid=1&Fmt=6&VInst=PROD&VType=PQD&RQT=309&VName=PQD&TS=1264711002&clientId=28564.
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Bubb, Damian H. "Spatial ecology of white-clawed crayfish Austropotamobius pallipes and signal crayfish Pacifastacus leniusculus in upland rivers, northern England." Thesis, Durham University, 2004. http://etheses.dur.ac.uk/3118/.
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The American signal crayfish Pacifastacus lernusculus, an invasive species widely introduced throughout Europe, is a major threat to native European crayfish species and is causing increasing concern because of its wide impact on aquatic ecosystems. This thesis investigates the within catchment expansion of signal crayfish populations in two upland rivers and the spatial ecology and movement of the introduced signal crayfish and the indigenous white-clawed crayfish Austropotamobius pallipes. Populations of signal crayfish are established and expanding on the upland rivers Wharfe and Ure. On the Wharfe the signal crayfish population is well established and now occupies about 30 km of river and is currently expanding at a rate in excess of 2 km year(^-1). On the Ure the signal crayfish population is younger and currently occupies 1.6 km and is currently expanding at about 0.5 km year(^-1). The range expansion is biased towards downstream in both rivers, by a ratio of about 3:1 (downstream:upstream).The movements and dispersal of white-clawed and signal crayfish was studied utilising a combination of radiotelemetry and internal and external Passive Integrated Transponder (PIT) tags. Radiotagged adult signal crayfish were capable of substantial active movements (maximum movement 790m in 79 days). The level of movement of adults suggests they may have the potential to be responsible for the observed rates of population expansion. Although the movements of radiotagged adult signal crayfish within main river channel were equally distributed upstream and downstream, in-stream barriers both natural and artificial were found to limit the upstream movements of PIT tagged crayfish and this may contribute to the observed downstream bias of signal crayfish population expansion. The movements and dispersal of PIT tagged white-clawed crayfish within a small upland high gradient stream were strongly biased towards downstream. Maximum movement of radiotagged adult signal crayfish occurred during midsummer. Temperature appeared to be a major factor influencing the timing and extent of movements between tracking periods although there was a large variation between individuals. All significant downstream movements made by crayfish were active movements and not the result of passive movement during periods of high discharge. There were no sex or size differences in the dispersal and movement of radiotagged and PIT tagged signal crayfish whilst in PIT tagged white-clawed crayfish size, sex, injuries and duration of tracking influenced extent of movement. The expansion of the signal crayfish population in the River Wharfe appears to lead to the progressive loss of white-clawed crayfish populations where they come into direct contact. Limited differences in the microhabitat utilised by the two species were found where the species were syntopic, suggesting the potential exists for direct competition between the two species. In addition signal crayfish showed greater movement and dispersal than white-clawed crayfish. This may contribute to the ability of signal crayfish to colonise rivers rapidly and may also offer a competitive advantage over white-clawed crayfish thus contributing to the observed replacement. The results are discussed in the context of the conservation and management of crayfish and the ecology of invasive species.
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Berry, Fiona Catherine. "The behavioural function of pheromones in crayfish." Thesis, University of Hull, 2008. http://hydra.hull.ac.uk/resources/hull:5756.
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Pacifastacus leniusculus and Procambarus clarkii are highly invasive freshwater crayfish and are having detrimental impacts on native species and habitats throughout Europe. The application of pheromone baits have been proposed as a way of increasing trap efficiency for population control, however the chemical identity of crayfish pheromones is unknown. An incomplete understanding of chemical communication has delayed progress in the development of appropriate bioassays. This thesis therefore focused on researching the natural context of chemical signalling by crayfish, including signal delivery and receiver response. Urine release by male and female crayfish was found to coincide with aggressive behaviours rather than reproductive behaviours. Female urine release was essential for initiating mating, with males detecting female receptivity by spying on hormones and metabolites released with threat signals. Physiological indicators of reception included a brief cardiac and ventilatory arrest followed by an increase in rate. Both behavioural and physiological responses formed the basis of a novel assay design. During courtship male crayfish do not appear to advertise by urine signals. This raised the question of whether chemical signals were important for female assessment of the quality of size-matched males. When given a free choice, females could not distinguish dominant and subordinate males through chemical signals alone. This suggests that females either use other criteria (e.g. size) for mate choice or perform cryptic postcopulatory mate choice. Blocking natural urine release of crayfish, which had previously fought to establish dominance, and artificially introducing urinary signals proved an effective bioassay for investigating the mechanisms of dominance hierarchy formation. Urine from the dominant male was the key factor in establishing dominance relationships. In the absence of dominant urine, subordinate males were less likely to retreat from aggressive bouts and fights were more intense. The mechanisms of signal delivery during agonistic encounters were investigated by measuring ventilatory activity. Increased ventilation rate was associated with highly aggressive behaviours and urinary signalling. This indicated crayfish create gill currents to disperse signals and increase transfer efficiency from sender to receiver. This thesis sheds light into the mechanism of chemical communication in crayfish and provides the basis for future bioassay guided purification of crayfish pheromones.
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Luan, Xin. "Interspecies aggression and social dominance in crayfish." Bowling Green, Ohio : Bowling Green State University, 2009. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=bgsu1256151469.
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Breinholt, Jesse W. "Testing Crayfish Evolutionary Hypotheses with Phylogenetic Methods." BYU ScholarsArchive, 2012. https://scholarsarchive.byu.edu/etd/3563.
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This dissertation focuses on increasing the understanding of the evolution processes that have contributed to the diversification of freshwater crayfish. Chapter one estimates the divergence time of the three crayfish families and tests the hypothesis that diversification is tied to the break-up of Pangaea, Gondwanna, and Laurasia. I find that the families of crayfish diverged prior to or in association with the break-up of the three super continents. Chapter two addresses the evolutionary history of the genus Cambarus, using molecular data to test hypotheses of relationships based on chela and carapace morphology. The results provide evidence that the morphology used to determine Cambarus relationships do not reflect evolutionary history and that convergent evolution of morphological traits is common in crayfish. Chapter three addresses evolution at the population level and tests for differences in the genetic population structure of two crayfish with different physiological needs. I find that physiological requirements of these crayfish have influenced their population genetic structure. The last chapter addresses a molecular based hypothesis that rates of mitochondrial evolution are reduced in cave crayfish that have increased longevity, reduced metabolism, and restricted diets compared to surface crayfish. I find that cave crayfish rates of mitochondrial evolution do not significantly differ from surface crayfish. Therefore, increased longevity, reduced metabolism, and restricted diets do not slow the rate of mitochondrial evolution as predicted in this group of cave crayfish.
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Belanger, Rachelle Marie. "An Interdisciplinary Investigation of the Role of Crayfish Major Chelae in the Discrimination of Conspecific Odours: from Morphology to Behaviour." Bowling Green, Ohio : Bowling Green State University, 2007. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=bgsu1182174766.
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Dawkins, Kathryn L. "A Study on Tenuibranchiurus and the Evolution of the Burrowing Clade of Australian Freshwater Crayfish." Thesis, Griffith University, 2015. http://hdl.handle.net/10072/367987.
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The overall aim of this thesis was to investigate the morphological and molecular diversity within Tenuibranchiurus, and to utilise these data to further the understanding of the evolution of this freshwater crayfish and the other genera of the Australian burrowing clade from both a phylogenetic and biogeographic perspective. The genus Tenuibranchiurus occurs within coastal eastern Australia and currently represents the largest gap in knowledge within this clade of crayfish. It is also the only monotypic parastacid genus, containing the single species T. glypticus. Additionally, it has morphological, phylogenetic, and geographical attributes that are not exhibited by other members of the burrowing clade, or by other freshwater fauna found throughout its distributional range. Examination and clarification of these unique features has the potential to elucidate evolutionary processes determining the distribution and genetic structure of the genus, the burrowing clade, and the freshwater fauna of coastal eastern Australia.Thesis (PhD Doctorate)
Doctor of Philosophy (PhD)
Griffith School of Environment
Science, Environment, Engineering and Technology
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au, S. Beatty@murdoch edu, and Stephen Beatty. "Translocations of freshwater crayfish: contributions from life histories, trophic relations and diseases of three species in Western Australia." Murdoch University, 2005. http://wwwlib.murdoch.edu.au/adt/browse/view/adt-MU20050718.152608.
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By examining Western Australian freshwater crayfishes, this thesis aims to further our understanding of how life-history strategies, trophic relationships and disease introductions contribute to the threats posed by introduced species. Reproductive and population biology of two species of freshwater crayfish endemic to Western Australia (the marron Cherax cainii and gilgie Cherax quinquecarinatus) and the introduced yabbie Cherax destructor were described. Multiple stable isotope analysis was employed to determine the trophic positions of sympatric populations of C. cainii and the invading. A serious microsporidian disease of freshwater crayfishes was also discovered in a wild population of C. destructor. These data were used to determine the potential threat that C. destructor poses to the endemic crayfishes of Western Australia.
Cherax cainii supports an iconic recreational fishery that has been in steady decline for three decades. It is likely that considerable plasticity in the biology of C. cainii exists amongst the ca 100 populations and that this may result in the current fishery management regulations being not effective in protecting all stocks. To test these hypotheses, the biology of C. cainii were described from populations occurring in an impoundment dam (Lake Navarino) at the approximate centre of its current range and in the Hutt River at the northernmost point of its range and compared with those from a previous study near the southernmost point of its distribution. The study confirmed these hypotheses. For example, the onset of spawning was later in the more southerly Lake Navarino population (August) than in the northerly Hutt River population (July). Furthermore, the respective orbital carapace lengths (OCL) at which C. cainii reached maturity in the two populations studied here differed markedly. The lengths at which 50% of female and male C. cainii matured in Lake Navarino were 32.1 mm and 28.6 mm OCL for females and males, respectively, compared with 70 mm and 40 mm OCL for females and males in the Hutt River, respectively. Therefore, these data clearly demonstrate that the current minimum legal size limit of 76 mm CL (~55 mm OCL) is ineffective in allowing females to undertake a spawning event prior to legal capture. It is therefore recommended that the minimum legal size limit be increased to 98 mm CL in the Hutt River to allow 50% of females to reach maturity prior to exploitation. Furthermore, as the spawning rate of mature female C. cainii in the Hutt River was low (10%) compared with those mature females in the more southerly Lake Navarino (96%), this increase in minimum legal size of capture is of particular importance should fisheries managers wish this translocated population to be exploited sustainably.
It is proposed that the much larger lengths at first maturity and low spawning rate in the Hutt River were due to faster growth rates likely caused by relatively high water temperatures and in response to competition with the sympatric, introduced crayfish, C. destructor, respectively. This highlights the plasticity of the biology of C. cainii and has considerable implications for effective management of the size-regulated recreational fishery.
Cherax quinquecarinatus, a south-western Western Australian endemic: occupies a broad range of aquatic systems, is likely to be an important component to those aquatic food webs, and is also subject to recreational fishing pressure. Cherax quinquecarinatus was found to mature at a relatively small size (cf C. cainii) with the L50s for females and males being 18.8 and 24.5 mm OCL, respectively, with the majority of C. quinquecarinatus first spawning at the end of their second year of life. The potential (ovarian) and pleopodal fecundities of C. quinquecarinatus were relatively low compared to other freshwater crayfishes, being 81.7 (b5.93 s.e.) and 77.1 (b13.76 s.e.), respectively. Cherax quinquecarinatus underwent an extended spawning period, from late winter to late summer (i.e. August to February). Three spawning events were facilitated by short brood and rapid gonadal recovery periods, traits consistent with other crayfish species able to exist in temporary environments.
The seasonal von Bertalanffy growth curve, fitted for the first 14 months of life for female and male C. quinquecarinatus, had respective K and OCLVs of 0.29 and 59.6 mm OCL for females, and 0.25 and 73.8 mm OCL for males, respectively. At 12 months of age, the OCLs of females and males were 14.7 and 14.1 mm, respectively. Estimates of total mortality (Z) were relatively high at 2.34 and 1.95 year-1 based on an age-converted catch curves for females and males, respectively, with a considerable proportion of this attributed to fishing mortality (exploitation rates of 0.76 and 0.75 for females and males, respectively). Cherax quinquecarinatus exhibited traits of both an r- and a K-strategist, which has likely to have aided the success of this species across a wide range of permanent and temporary systems.
During this study, C. destructor was found in many wild aquatic systems in the southern Pilbara and Southwest Coast Drainage Divisions of Western Australia. This is of great concern as all native freshwater crayfishes in Western Australia are restricted to the southwest while the aquatic systems of the Pilbara Division do not naturally house freshwater crayfish.
Despite the reported impacts that invasive freshwater crayfish species may have on native crayfish species and food webs, the biology and ecology of C. destructor in wild systems in Western Australia was unknown and therefore an assessment of their potential impact has not previously been possible. Cherax destructor was collected monthly from the Hutt River (Pilbara Drainage Division) for determination of life-history and reproductive biology in a wild aquatic system in Western Australia. Proliferation in that system was attributed to specific traits including: a small size at first maturity with 50% (L50) of females and males maturing at 21.6 and 26.5 mm OCL, respectively, a size attained at the end of their first year of life; a protracted spawning period (July to January); high mean ovarian fecundity of 210.2 (b9.24 s.e.); and a rapid growth rate that was comparable to the larger sympatric C. cainii in this system. Life-history characteristics of C. destructor in the Hutt River were typical of many other invasive crayfish species and were likely to have aided in its establishment.
This study is the first to examine the diet and trophic position of sympatric populations of two species of freshwater crayfish in Australia. By determining temporal changes in the assimilated diet and trophic positions of sympatric populations of C. destructor and C. cainii, this study tested the hypothesis that C. destructor has the potential to compete with C. cainii for food resources. This was tested using multiple stable isotope analyses with samples of C. cainii, C. destructor and a wide variety of their potential food sources analysed in the Hutt River in summer and winter, 2003. Summer samples indicated that these species occupied similar predatory trophic positions when their assimilated diet consisted of a large proportion of Gambusia holbrooki (either when the fish were alive or deceased due to a presumably large natural mortality rate). Although C. cainii continued to assimilate animal matter based on winter signatures, those of C. destructor appeared to shift towards more of herbivorous trophic position. It appeared that C. destructor and C. cainii were keystone species in the Hutt River and were likely to be important in the cycling of nutrients and in structuring the aquatic food web that may have been considerably altered by their introduction into this system.
As C. destructor has the ability to switch trophic positions, when an otherwise abundant, high protein food sources (i.e. fish) becomes limited (as was the case in winter in the Hutt River), it was able to co-exist with C. cainii. Furthermore, the ability of C. destructor to switch from a diet of fish in summer to a predominantly herbivorous/detrital diet in winter suggests that it may compete for food resources with the other smaller native freshwater crayfishes (such as C. quinquecarinatus) in the small, unproductive lotic and lentic systems common to south-western Australia, which often lack fish during summer.
The recently described Thelohania parastaci was identified in C. destructor in the Hutt River and Vavraia parastacida, previously recorded from C. cainii and C. quinquecarinatus populations elsewhere in the region, appeared to be infecting C. cainii. Although not confirmed to have infected C. cainii, the presence of T. parastaci in the sympatric C. destructor is of serious concern as there is the potential that the disease may be able to be transmitted to the native congeners of the region, particularly as C. destructor establishes itself in other natural waterbodies.
This thesis has addressed major gaps in the understanding of the biology, ecology and threats to the unique freshwater crayfish fauna of Western Australia. The results of this research highlight the plasticity of the biology and ecology of freshwater crayfishes and enabled an initial assessment to be made of the potential ecological impacts of an invading species. Considerable implications for fisheries and other natural resource management agencies ensuing from this research are detailed. The conclusions drawn from this study are also discussed in the broader context of invasive species in general and important future investigations stemming from these results are identified.
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Welch, Shane Matthew. "Multiscale habitat associations of three primary burrowing crayfish." Connect to this title online, 2006. http://etd.lib.clemson.edu/documents/1175184962/.
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Bierbower, Sonya M. "ENVIRONMENTAL EFFECTS ON BEHAVIOR AND PHYSIOLOGY IN CRAYFISH." UKnowledge, 2010. http://uknowledge.uky.edu/gradschool_diss/778.
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Despite dramatic morphological differences between animals from different taxa, several important features in organization and sensory system processing are similar across animals. Because of this similarity, a number of different organisms including mammals, insects, and decapod crustaceans serve as valuable model systems for understanding general principles of environmental effects. This research examines intrinsic and extrinsic factors by behaviorally and physiologically means to identify the impact of environmental conditions on two distinct crayfish species- Procambarus clarkii (surface) and Orconectes australis packardi (cave).
The research identified behavioral and physiological responses in these two morphological and genetically distinct species. The studies also examined multiple levels of complexity including social behavior, an autonomic response, chemosensory capabilities and neuronal communication, identified comparative similarities/differences, addressed learning and environmental influences on learning and examined behavioral and cellular responses to high levels of carbon dioxide. I found environmental factors directly influence crayfish behavior of social interactions. Interactions were more aggressive, more intense and more likely to end with a physical confrontation when they took place 'in water' than 'out of water'. The modified social interaction resulted in a altered fighting strategy.
A study on motor task learning was undertaken which showed similar learning trends among these crayfish species despite their reliance on different sensory modalities. I also demonstrated learning was dependent on perceived stress by the organism. Previously trained crayfish inhibited from completing a task showed significant increase in an autonomic stress response.
Studies on the behavioral and physiological responses to CO2 revealed that high [CO2] is a repellent in a concentration dependent manner. The autonomic responses in heart rate and an escape tailflip reflex shows complete cessation with high [CO2]. A mechanistic effect of CO2 is by blocking glutamate receptors at the neuromuscular junction and through inhibition of the motor nerve within the CNS.
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Firkins, Ian. "Environmental tolerances of three species of freshwater crayfish." Thesis, University of Nottingham, 1993. http://eprints.nottingham.ac.uk/11282/.
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The only species of crayfish native to the British Isles, i.e. Austropotamobius pallipes, is presently widely distributed throughout much of England, Wales and Ireland. The main controlling factor behind this distribution is the predominantly "bicarbonate" freshwater system of the British Isles. In geological terms, native crayfish are generally found in areas of chalk, carboniferous or magnesium limestone, or drift deposits of boulder clay. More recently, native crayfish have been affected by a general decline in the quality of Britain's freshwater system largely due to sewage effluent and agricultural. By far the majority of native crayfish records are associated with water bodies of very good or good quality, with the result that many populations of A. pallipes are isolated in small, good quality headwaters, due to the degree of pollution in the main rivers acting as "chemical barriers". The last two decades have seen a number of alien species of crayfish imported into England and Wales for aquaculture and culinary purposes. Deliberate and accidental introductions have resulted in the establishment of populations of these species in the wild, the most widespread being the North American signal crayfish Pacifastacus leniusculus and the European slender-clawed crayfish Astacus leptodactylus. An important and devastating consequence of the introduction of alien species of crayfish has been the spread of the crayfish plague fungus Aphanomyces astaci, possibly initiated by infected P. leniusculus. Both A. pallipes and A. leptodactylus are susceptible to the disease, with the result that populations of A. pallipes have been eliminated from, whole lengths of river, such as the River Kennet and the Hampshire River Avon. The nature of the disease and the ease with which it is spread means that crayfish is an ongoing problem in England and Wales, with new populations of A. pallipes regularly becoming affected. The distribution of alien species in the British Isles is an artificial one, initially determined by man, although consideration of water quality may have determined the choice of aquaculture sites. However, established populations of alien species in the wild will be subject to the same constraints as A. pallipes, which will affect their subsequent spread and distribution in the freshwater system of England and Wales. A greater tolerance of environmental factors may allow alien species to inhabit waters not currently occupied by the native species, such as polluted or estuarial waters, and possibly threaten populations of A. pallipes protected by "chemical barriers". This study investigated and compared some of the environmental tolerances of A. pallipes, A. leptodactylus and P. leniusculus and consisted of two parts: 1.) Comparison of the tolerance of A. pallipes, A. leptodactylus and P. leniusculus to four common pollutants; chloride, copper, ammonia and lindane, using lethal and sublethal toxicity tests. No species was found to have a greater overall pollution tolerance on the basis of the toxicants used in this study. Median lethal concentrations (LC50) obtained from lethal studies with stage II juveniles indicated that A. leptodactylus juveniles were most tolerant of chloride, but were very sensitive to lindane. P. leniusculus stage II juveniles were least tolerant of chloride, but of equal or greater tolerance when tested in larger juvenile stages, and were most tolerant of copper. A. pallipes juveniles were very sensitive to copper, and all three species showed a similar sensitivity to ammonia. However, episodic experiments with ammonia and copper indicated that differential short-term tolerance to toxicants, i.e. less than 24 hours, may be important in determining the outcome of episodic pollution events on crayfish populations. Salinity studies indicated high resistance to chloride, with all three species able to tolerate salinities up to 50% seawater, implying freshwater crayfish may be able to tolerate estuarine conditions. Accumulation studies with P. leniusculus inferred resistance to high levels of copper in the environment, with a substantial storage capacity for the metal and a regulatory mechanism for excretion of excess amounts. However, establishment of populations under high saline or high copper conditions would be limited by the lower tolerance of early life stages. Similarly, sublethal studies implied that sublethal toxicant effects on early life stages may be important in determining presence or absence of crayfish from a waterbody, through effects on recruitment. 2.) Comparison of the thermal relations of A. pallipes, A. leptodactylus and P. leniusculus, using tolerance, growth and respiration experiments. Results from tolerance experiments showed that P. leniusculus had a greater overall thermal tolerance, so is more resistant to changes in environmental temperature, such as in waters affected by thermal discharges or in waters affected by drought and reduced flow. In growth experiments P. leniusculus grew faster at all temperatures tested and was predicted to grow at temperatures unsuitable for the other species. Therefore, P. leniusculus would not only be able to survive and grow in conditions unsuitable for A. pallipes and A. leptodactylus, but will also grow faster where favourable conditions exist for all three species. Field experiments showed that, although P. leniusculus juveniles were smaller on release from the female, they were released earlier and their faster growth rate allowed them to maintain a distinct size advantage over A. pallipes juveniles, which was very marked by the end of the growing season. Large size is a key element in the attributes leading to competitive success in other crayfish species. Field observations on mixed populations of plague-free P. leniusculus and A. pallipes indeed show that signal crayfish are superior competitors, eventually eliminating A. pallipes. Therefore temperature effects may be important in determining the outcome of competition in mixed crayfish populations.
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Guan, Ruizhang. "Ecological studies on the crayfish Pacifastacus leniusculus (Dana)." Thesis, University of Buckingham, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.282636.
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James, Joanna. "The impact of invasive crayfish on aquatic ecosystems." Thesis, Cardiff University, 2015. http://orca.cf.ac.uk/89031/.
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Crayfish are keystone species and ecosystem engineers that affect the structure and function of aquatic ecosystems. Whilst ecological impacts are caused by crayfish in their native range, non - native crayfish species typically have a greater ef fect on some other aquatic organisms and ecosystem processes (Chapter 2). Crayfish are extremely successful invaders that often cause declines in native cra yfish (Chapter 3). Of the 7 non - native crayfish species in the UK, the signal crayfish ( Pacifastacus leniusculus ) is currently the most widespread (Chapter 3). Field and laboratory data, however, suggest that in parts of the UK signal crayfish are being outcompeted by more recently introduced virile crayfish ( Orconectes cf. virilis ) (Chapter 4). Non - native crayfish also threaten native crayfish through disease, notably crayfish plague ( Aphanomyces astaci ), transmission. Whilst non - native North American crayfish are largely resistant to A. astaci , infection in susceptible native European species is usually lethal. Within this study 23 signal crayfish populations were screened for A. astaci and 13 were infected (Chapter 5). Virile crayf ish from the UK were also infected with A. astaci , and therefore should also be considered as a transmission pathway for this pathogen in the UK (Chapter 6). Whilst the majority of studies on crayfish symbionts are focused on A. astaci , crayfish host a wid e range of micro and macro - parasites. One group of particular interest are branchiobdellidans (Annelida: Clitellata). Two species of these ectosymbionts, Xironogiton victoriensis and Cambarincola aff. okadai , were recently discovered on invasive signal cra yfish in the UK (Chapter 7). Owing to their abilities to survive for extended periods off the host and reproduce rapidly both species have a high invasion potential in the UK (Chapter 8). Laboratory experiments show that signal crayfish infested with X. victoriensis were less aggressive and poorer foragers than uninfested c rayfish , therefore these symbionts may influence signal crayfish invasion dynamics (Chapter 9).
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Peay, Stephanie. "Developing tools for the management of freshwater crayfish." Thesis, University of Leeds, 2013. http://etheses.whiterose.ac.uk/6343/.
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The introduction of non-indigenous crayfish into Europe is causing the loss of indigenous crayfish, due to transmission of crayfish plague and competition. Other factors are reductions of habitat quality and in some areas harvesting. This study deals with issues facing environmental agencies and other resource managers about how manage crayfish; from prevention of further introductions, to eradication where feasible, or control if it is cost-effective, or where it is not, then applying measures to mitigate the effects of invasion by finding or establishing isolated areas for indigenous crayfish, i.e. ark sites. It provides a range of decision-making tools for management. The study includes a literature-based risk assessment for non-indigenous crayfish in Great Britain. It presents the first evidence of the negative impact of signal crayfish Pacifastacus leniusculus on salmonid fish in a headwater stream. The study shows how the technique of biocide treatment against signal crayfish has developed, the outcomes and the lessons learned from the projects and factors that will contribute to other successful eradication treatments in future. Another new potential method for eradication or control is electric shock treatment, which was field-tested in this study. As an aid to assessing the feasibility of eradication or control, a simple cost-model was developed using the potential impact on salmonid fish and a re-stocking cost as a surrogate for environmental impact of crayfish invading a catchment. This was used to compare the costs of eradication or control and showed the benefit of early eradication and the unsustainably high cost of control by trapping. As signal crayfish are already widespread in England and Wales, risk-based selection criteria were developed to help identify potential ark sites for white-clawed crayfish. In addition, a decision-making tool has been prepared to help conservation managers understand the issue and develop conservation action plans at catchment scale.
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Simon, Jodie L. "Male-Female Communication in the Crayfish Orconectes Rusticus: The Use of Urinary Signals in Reproductive and Non-Reproductive Pairings." Connect to this title online, 2006. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=bgsu1148415041.
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Filipová, Lenka. "Genetic variation in North American crayfish species introduced to Europe and the prevalence of the crayfish plague pathogen in their population." Poitiers, 2012. http://theses.univ-poitiers.fr/25202/2012-Filipova-Lenka-These.pdf.
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Les invasions biologiques de crustacés représentent une sérieuse menace pour les espèces natives d'Europe. Ma thèse porte sur les écrevisses non-indigènes introduites en Europe et sur leur parasite Aphanomyces astaci, le pathogène de la peste de l'écrevisse. Les chapitres I-V portent sur la diversité génétique des écrevisses d'Amérique du Nord. Nous avons montré que chez deux espèces avérées invasives, la variabilité génétique varie significativement. Orconectes limosus a été introduite en Europe probablement en une seule fois, avec peu d'individus. La variabilité de l'ADN mitochondrial en Europe est relativement basse (chapitre I), même si une variation modérée des marqueurs nucléaires dans ses populations d'Europe centrale (chapitre II). Par contre, Pacifastacus leniusculus a été introduite en plusieurs fois, avec un grand nombre d'individus. Ses populations européennes sont génétiquement très diverses (chapitre III). Le chapitre V montre que la méthode du code barres génétique est utile pour une identification des nouvelles espèces introduites en Europe. Le parasite A. Astaci est apparu en Europe en 1859 et a largement réduit les populations d'écrevisses natives. Les écrevisses d'Amérique du Nord peuvent être porteuses du pathogène et le transmettre aux espèces européennes. Les informations sur l'infestation par A. Astaci chez les écrevisses invasives sont donc importantes pour la protection des espèces natives. Dans le chapitre VI, nous confirmons que P. Leniusculus est un réservoir du pathogène en France et représente un danger sérieux pour les espèces natives. Dans le chapitre VII, nous validons que la méthode de real-time PCR est très appropriée pour la détection du pathogèneBiological invasions by crustaceans represent a serious threat for native species in Europe. My thesis brings information on non-indegenous freshwater crayfish introduced to Europe and their parasite Aphanomyces astaci, the pathogen of the crayfish plague. Chapters I-V focus on genetic variation in North American crayfish. We showed that in two crayfish specie, both successful invaders in Europe, genetic variation differs significantly, reflecting their different colonization histories on the continent. Orconectes limosus was likely introduced to Europe just once, in small numbers. Variation at the mitochondrial DNA level in Europe is relatively low (chapter I), although some variation was revealed by nuclear markers in its Central European populations (chapter II). In contrast, Pacifastacus leniusculus was introduced to Europe several times, in large numbers. Its European populations are genetically highly diverse (chapter III). Chapter V showed the utility of DNA barcoding for identification of newly established species in Europe. The parasite A. Astaci appeared in Europe in 1859 and has substantially reduced native crayfish populations. North American crayfish may carry the pathogen and transmit it to European species. Information on A. Astaci in invasive crayfish is therefore important for conservation of native species. In chapter VI, we confirm that P. Leniusculus serves as a reservoir of the pathogen in France and represents a serious danger for native species. In chapter VII, we validate that a real-time PCR is suitable for the detection of the pathogen
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Jiravanichpaisal, Pikul. "White Spot Syndrome Virus Interaction with a Freshwater Crayfish." Doctoral thesis, Uppsala : Acta Universitatis Upsaliensis : Univ.-bibl. [distributör], 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-5776.
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Middleton, Dawn. "Comparative aspects of the immunobiology of freshwater crayfish species." Thesis, University of Nottingham, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.283632.
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Hayes, Richard Birchall. "Consequences for lotic ecosystems of invasion by signal crayfish." Thesis, Queen Mary, University of London, 2012. http://qmro.qmul.ac.uk/xmlui/handle/123456789/2484.
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Non-native invasive species are major drivers of biodiversity loss and ecosystemlevel modification. The signal crayfish (Pacifastacus leniusculus) is a highly successful invasive species and demonstrates traits often seen in keystone species, including top-down predatory effects, a high degree of omnivory, and an ability to physically modify its habitat. From field surveys, and in situ and artificial channel experiments, I show that signal crayfish have direct and indirect impacts on the benthos, as well as ecosystem process rates, in lowland, chalk stream ecosystems. Furthermore, I show that these effects are often dependent on crayfish life stage. I demonstrate that two native fish species (chub, Leuciscus cephalus and bullhead, Cottus gobio) may be affected positively, as well as negatively, by signal crayfish invasion. In addition, population genetics reveals overall high levels of genetic diversity in populations of signal crayfish in the UK.
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Tambo, Guillermo Eduardo Willis-Jones. "The indirect impacts of ecosystem engineering by invasive crayfish." Thesis, Queen Mary, University of London, 2018. http://qmro.qmul.ac.uk/xmlui/handle/123456789/46825.
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Bioturbation by invasive crayfish can significantly alter sediment properties and its transport in invaded water bodies; however, the indirect impacts of this on ecosystem functioning are poorly understood. In this thesis I present data from mesocosm and field manipulation experiments used to assess the effect of bioturbation by three widely distributed invasive crayfish species (Procambarus clarkii, Pacifastacus leniusculus and Astacus leptodactylus) on a variety of ecosystem properties across seasons. In the mesocosm experiments, P. clarkii caused significantly more bioturbation than the other species, although increased bioturbation by all species in the spring and/or summer was associated with: reduced dissolved oxygen concentrations in near-surface water, indicating a large increase in oxygen demand by the water column; increased methane oxidation potential within the water (MOPwat), indicating the re-suspension of methane oxidising bacteria (MOB) along with the sediment; and a shift in zooplankton community structure towards dominance by large cladoceran species. Stable isotope analysis of the zooplankton showed a strong relationship between δ13C and MOPwat, suggesting that bioturbation increases MOB consumption. Given the importance of zooplankton as a trophic link to the higher food web, crayfish bioturbation may increase the importance of methane derived (chemosynthetic) carbon in invaded ecosystems. Temperature was identified as the key driver of seasonal variations in crayfish bioturbation intensity through laboratory mesocosm experiments, enabling estimation of the full annual pattern of bioturbation intensity for each species. The optimal temperature for P. clarkii was much higher than for the other species meaning that its bioturbation impacts exhibited large seasonal fluctuations whilst P. leniusculus and A. leptodactylus maintained a lower but more consistent level. Field manipulation experiments of enclosed sections of Chalgrove Brook, Oxfordshire, found significant bioturbation activity by P. leniusculus in early autumn; however, the increase in turbidity was too small to detect other effects observed in the mesocosm experiments.
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Bhimani, Rohan. "Operant Place Aversion in the Rusty Crayfish, Orconectes rusticus." Bowling Green State University / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1415978513.
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Wolf, Mary Caroline. "Neural and behavioral responses to complex stimuli using crayfish as a model system." Connect to this title online, 2005. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=bgsu1130864221.
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Skorupski, P. "Central nervous and proprioceptive control of crayfish walking leg motoneurones : An intracellular microelectrode study of the isolated 4. thoracic ganglion." Thesis, University of Bristol, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.354467.
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Clark, Jennifer M. "Abiotic and biotic factors affecting size-dependent crayfish (Orconectes obscurus) distribution, density, and survival." [Kent, Ohio] : Kent State University, 2009. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=kent1239497384.
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Thesis (Ph.D.)--Kent State University, 2009.Title from PDF t.p. (viewed Nov. 16, 2009). Advisor: Mark Kershner. Keywords: crayfish; stream; predation; current velocity; water depth; grain size; resource competition. Includes bibliographical references.
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Channell, Katherine B. "Implementation of a spatial-temporal focus to predict habitat locations and distribution of Cambarus veteranus." Huntington, WV : [Marshall University Libraries], 2004. http://www.marshall.edu/etd/descript.asp?ref=394.
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Thesis (M.S.)--Marshall University, 2004.Title from document title page. Document formatted into pages; contains ix, 88 p. including illustrations. Includes abstract. Includes bibliographical references (p. 72-76).
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Dillman, Casey B. "Phylogenetic systematics of Orconectes stygocaneyi, with a genealogical analysis of the Ozark cave crayfishes /." free to MU campus, to others for purchase, 2004. http://wwwlib.umi.com/cr/mo/fullcit?p1421131.
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Mueller, Karl W. "Shelter competition between native signal crayfish and non-native red swamp crayfish in Pine Lake, Sammamish, Washington : the role of size and sex /." Online version, 2007. http://content.wwu.edu/cdm4/document.php?CISOROOT=/hcc&CISOPTR=2490&REC=15.
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Buhay, Jennifer E. "Phylogeographic analyses of obligate and facultative cave crayfish species on the Cumberland Plateau of the Southern Appalachians /." Diss., CLICK HERE for online access, 2006. http://contentdm.lib.byu.edu/ETD/image/etd1415.pdf.
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Northcutt, Brian S. W. "Effects of External Electric Fields on Light Transmittance in Isolated Crayfish Nerves." Thesis, University of North Texas, 1995. https://digital.library.unt.edu/ark:/67531/metadc279205/.
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Acute effects of a pulsed external electric field (PEEF) at 20 V/cm and a d.c. EEF at 90 V/cm on light
transmittance in an isolated compound crayfish nerve was measured. In a third series, the nerve was pre-treated with the Na+ channel blocker tetrodotoxin (TTX). A PEEF produced an irreversible increase in the variation of light transmittance in normal nerves but a reversible increase in TTX treated nerves. This data was statistically insignificant. The d.c. EEFs produced a reversible and statistically significant enhancement of variation in light transmittance in both untreated and TTX-treated nerves. The
findings may be due to either (1) an alteration in the ion/fluid flux within the nerve or (2) a physical alteration of protein molecules in the membranes.
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Warren, Amy H. "Male dominance and sexual selection in the crayfish Orconectes Quinebaugensis." Worcester, Mass. : Worcester Polytechnic Institute, 2009. http://www.wpi.edu/Pubs/ETD/Available/etd-043009-140131/.
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Fero, Kandice Christine. "Social dominance a behavioral mechanism for resource allocation in crayfish /." Bowling Green, Ohio : Bowling Green State University, 2008. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=bgsu1213213435.
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Noonin, Chadanat. "Melanization and Hemocyte Homeostasis in the Freshwater Crayfish, Pacifastacus leniusculus." Doctoral thesis, Uppsala universitet, Jämförande fysiologi, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-209209.
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Blood cells or hemocytes play important roles in immunity. They are a major source of many immune-related molecules such as antibodies in adaptive immunity of vertebrates and prophenoloxidase (proPO) in invertebrates. In the crayfish Pacifastacus leniusculus, the proPO-system has been reported to be an important component of immune responses against microorganisms. In this study, several mutant strains of Aeromonas hydrophila were used to reveal that LPS (lipopolysaccharide) is an important factor for the pathogenicity of A. hydrophila, strongly inducing the proPO system and melanization. This proPO activating system is a multistep process, which has to be tightly controlled to avoid the harmful side effects of toxic intermediates. Many regulating factors have been reported to fine-tune the proPO-system. In this study, the cleavage of caspase-1-like activity was shown to be a novel negative regulator of PO activity in crayfish. Moreover, the fragments obtained by cleavage of proPO by the proPO-activating enzyme and caspase-1-like protein increased bacterial clearance. Thus, the peptides generated also have important biological functions. In addition to being a source of immune proteins, hemocytes also participate in phagocytosis, encapsulation, and nodulation. An infection normally causes a reduction of hemocyte numbers. Consequently, hemocyte homeostasis is important for maintaining appropriate hemocyte numbers in the circulation of the animal. This study shows that the reactive oxygen species level in the anterior proliferation center of crayfish hematopoietic tissue (HPT), together with cell proliferation, was increased during infection. Pl-β-thymosins were proposed to be involved in hemocyte homeostasis by increasing stem cell migration and thus increasing the circulating hemocyte number. Crayfish hemocyte numbers, as well astakine (Ast1 and Ast2) expression in hemocytes and HPT, were previously shown to be under circadian regulation. Here, we show that Ast1, Ast2, and proPO exhibit rhythmic expression in the crayfish brain similarly to their orthologs, prokineticin 1, prokineticin 2 and tyrosinase, respectively, in the zebrafish brain. Tyrosinase expression was detected in zebrafish brain cells while PO-positive cells were identified as hemocytes that had infiltrated into the crayfish brain. Therefore, this information suggests a close relationship between crayfish hemocytes and the crayfish brain as well as vertebrate neurons.
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Jones, Julia Patricia Gordon. "The sustainability of crayfish harvesting in Ranomafana National Park, Madagascar." Thesis, University of Cambridge, 2004. https://www.repository.cam.ac.uk/handle/1810/284387.
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Madagascar's freshwater crayfish, belonging to the endemic genus Astacoides, are harvested throughout their range in the eastern highlands of the country. They provide an important source of protein and revenue to local communities but there is concern that the harvest may be unsustainable. In this thesis I assess the sustainability of crayfish harvesting in and around Ranomafana National Park, an area well known for its reliance on crayfish harvesting. Six taxa (belonging to four described species) are found in the Ranomafana area. Most families in villages with access to forest carry out some harvesting for subsistence use. Due to variation in local taboos (fady) and in access to forest, commercial crayfish harvesting is very important in only three of the 27 villages I visited. However, in these villages crayfish revenue is very important, particularly to poorer households. One species, Astacoides granulimanus, dominates the harvest: more than 95% of crayfish caught in the harvesting village of Vohiparara are of this species. I used a mark-and-recapture study involving more than 26,000 A. granulimanus across 79 sites under a range of harvesting intensities to estimate demographic parameters (growth, fecundity and survival) and investigate density-dependent control of growth and fecundity. No evidence for density-dependent control of growth was found, but the density of large crayfish negatively influenced the proportion of females of a given size which reproduced. I investigated the sustainability of the harvest of A. granulimanus using two approaches: I) comparing population structure and density under varying harvesting intensity and II) using population models to investigate the forest area necessary to provide the observed annual harvest from one harvesting village and comparing that with the area available. The conclusions are encouraging as they suggest that the A. granulimanus harvest in the Ranomafana area may be sustainable under current conditions. Preliminary work suggests habitat loss may be a more immediate threat, so scarce conservation resources should perhaps be concentrated on reducing habitat loss rather than enforcing a ban on harvesting.
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Martin, Arthur Leo III. "Underlying Mechanisms That Affect Crayfish Agonistic Interactions and Resource Acquisition." Bowling Green State University / OhioLINK, 2007. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1181230800.
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Slutzker, Juliet M. "Impacts of Road Crossings and Flow on Crayfish Population Structures." Bowling Green State University / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1428515728.
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Blake, Michael A. "Defence against predators by juvenile signal crayfish (Pacifastacus leniusculus, Dana)." Thesis, University of Leicester, 1993. http://hdl.handle.net/2381/34156.
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This study investigated the defensive responses of juvenile signal crayfish (Pacifastacus leniusculus, Dana) to two putative predators, perch (Perca fluviatilis, L.) and eel (Anguilla anguilla, L.), and attempted to determine the Importance of direct and indirect predatory effects on the distribution of newly independent Juvenile crayfish in a Swedish pond. Eels are thought to be more detrimental to crayfish populations than perch. Experiments using juvenile crayfish did not support this assertion. Visual and chemical stimuli elicited crayfish avoidance behaviour. This was most marked when both stimuli were presented together. Both predators elicited similar avoidance behaviour. Crayfish were less active by day, spending more time under shelter. Shelter provided by vegetation and substrata reduced crayfish mortality. Crayfish also avoided small non-predatory fish (Leucaspius delineates, Heckel). It is suggested that these fish indirectly increased crayfish mortality. Adult crayfish increased juvenile crayfish mortality but caused juveniles to be more active by day than at night. These responses illustrate the conflicting demands on crayfish defensive behaviour in multi-predator environments. Mechanical and visual stimuli elicited evasive behaviour. Crayfish evaded predatory strikes by perch and eels. The response to eels was delayed. Perch chased fleeing crayfish, and caught more crayfish than eels, which never chased prey. Initially, perch preyed on juvenile crayfish more rapidly than eels. Despite having distinct foraging behaviours, perch and eels produced similar crayfish mortalities. If eels are more detrimental than perch to crayfish populations, this may be a result of differences in size selective predation. The initial distribution of newly independent crayfish in a Swedish pond was influenced by the distribution of gravid female crayfish. Perch preyed on juvenile crayfish but were not a major factor determining crayfish distribution. Intraspecific competition and Invertebrate predation may have had a greater effect. Crayfish populations may be influenced by perch predation on yearling crayfish.
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Carpenter, Jeanette 1960. "Effects of introduced crayfish on selected native fishes of Arizona." Diss., The University of Arizona, 2000. http://hdl.handle.net/10150/284145.
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The virile crayfish (Orconectes virilis), an aggressive polytrophic species, has been introduced into many Arizona streams. I investigated competition and predation between this crayfish and several native Arizona fishes. I conducted field experiments to assess competition for food between crayfish and fish, and laboratory experiments to examine competition for shelter and food, and predation. In Sabino Creek, I manipulated crayfish densities in isolated pools to examine effects of crayfish on growth, mortality, and recruitment of Gila chub (Gila intermedia). Regardless of crayfish density, Gila chub declined slightly in weight and condition. Mortality and recruitment did not differ between densities of crayfish. I examined crayfish effects on benthic macroinvertebrates, a submerged aquatic macrophyte and associated invertebrates, and three fish species in a small stream in the White Mountains by fencing eight stream sections to prevent movement. The three fishes were speckled dace (Rhinichthys osculus), Sonora sucker (Catostomus insignis), and desert sucker (C. clarki). Molluscs > 10 mm and macrophytes were less abundant at sites with a high density of crayfish than at sites with low crayfish densities. Insect diversity was lower in high- vs. low-density sites. No treatment effect was observed on growth or condition of individually marked fish. Short-term laboratory experiments demonstrated predatory interactions and competition for shelter between crayfish and Gila chub, desert sucker, and speckled dace. Crayfish used shelter more than fish, displaced fish from shelter, and frequently attacked fish. Fish never attacked crayfish, and only once displaced crayfish from shelter. In predation experiments, crayfish preyed upon all species, but preyed most heavily upon desert suckers. Fish never altered use of the water column in the presence of crayfish. Density manipulation experiments in a laboratory measured food competition between crayfish and two native fishes. Growth of Gila chub was less affected by crayfish than by increased density of Gila chub. Thus crayfish are not strong competitors with Gila chub for food. However, growth of flannelmouth sucker (Catostomus latipinnis) was negatively impacted by presence of crayfish. These laboratory experiments provide evidence that introduced crayfish can reduce fish growth by competition for food, and that native fishes are vulnerable to crayfish predation.
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Fletcher, Kenneth A. "Febrile response and activity in the crayfish, Pacifasticus leniusculus trowbridgii." PDXScholar, 1988. https://pdxscholar.library.pdx.edu/open_access_etds/3809.
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Poikilothermic and endothermic animals demonstrate febrile response to infection with bacteria or to injection with endogenous pyrogen extract of Prostaglandin E1. Febrile response is measured in endotherms as a relative change in metabolically achieved body temperature and in poikilotherms as an increase in selected temperatures relative to previously established preferred temperatures. Final preferendum change with environmental factors or associated physiological states.
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Crawford, Allison Clare. "Evolution and function of cellulase genes in Australian freshwater crayfish." Thesis, Queensland University of Technology, 2006. https://eprints.qut.edu.au/16274/1/Allison_Crawford_Thesis.pdf.
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The most abundant organic compound produced by plants is cellulose, however it has long been accepted that animals do not secrete the hydrolytic enzymes required for its degradation, but rely instead on cellulases produced by symbiotic microbes. The recent discovery of an endogenous cDNA transcript encoding a putative GHF9 endoglucanase in the parastacid crayfish Cherax quadricarinatus (Byrne et al., 1999) suggests that similar cellulase genes may have been inherited by a range of crustacean taxa. In this study, the evolutionary history of the C. quadricarinatus endoglucanase gene and the presence of additional GHF9 genes in other decapod species were investigated. The activity of endoglucanase and endoxylanase enzymes within several cultured decapod species were also compared.
The evolutionary history of the C. quadricarinatus endoglucanase gene was assessed by comparing intron/exon structure with that of other invertebrate and plant GHF9 genes. The coding region of the gene was found to be interrupted by eleven introns ranging in size from 102-902 bp, the position of which was largely conserved in both termite and abalone GHF9 genes. These structural similarities suggest GHF9 genes in crustaceans and other invertebrate taxa share a common ancestry. In addition, two introns were observed to share similar positions in plant GHF9 genes, which indicates this enzyme class may have been present in ancient eukaryote organisms.
The presence of GHF9 genes in C. quadricarinatus and various other decapod species was then explored via degenerate primer PCR. Two distinct GHF9 gene fragments were determined for C. quadricarinatus and several other Cherax and Euastacus parastacid freshwater crayfish species, and a single GHF9 gene fragment was also determined for the palaemonid freshwater prawn Macrobrachium lar. Phylogenetic analyses of these fragments confirmed the presence of two endoglucanase genes within the Parastacidae, termed EG-1 and EG-2. The duplication event that produced these two genes appears to have occurred prior to the evolution of freshwater crayfish. In addition, EG-2 genes appear to have duplicated more recently within the Cherax lineage. The presence of multiple GHF9 endoglucanase enzymes within the digestive tract of some decapod species may enable more efficient processing of cellulose substrates present in dietary plant material.
Endoglucanase and endoxylanase enzyme activities were compared in several parastacid crayfish and penaeid prawn species using dye-linked substrates. Endoglucanase activity levels were higher in crayfish compared with prawn species, which corresponds with the known dietary preferences of these taxa. Endoglucanase temperature and pH profiles were found to be very similar for all species examined, with optimum activity occurring at 60°C and pH 5.0. These results suggest endoglucanase activity in penaeid prawns may also be derived from endogenous sources. Additional in vitro studies further demonstrated crayfish and prawn species liberate comparable amounts of glucose from carboxymethyl-cellulose, which indicates both taxa may utilise cellulose substrates as a source of energy. Endoxylanase temperature and pH profiles were also similar for all crayfish species examined, with optimal activity occurring at 50°C and pH 5.0. These results suggest xylanase activity in crayfish may originate from endogenous enzymes, although it is unclear whether this activity is derived from GHF9 enzymes or a different xylanase enzyme class. In contrast, no endoxylanase activity was detected in the three prawn species examined.
Together, these findings suggest a wide range of decapod crustacean species may possess endogenous GHF9 endoglucanase genes and enzymes. Endoglucanases may be secreted by various decapod species in order to digest soluble or amorphous cellulose substrates present in consumed plant material. Further biochemical studies may confirm the presence and functional attributes of additional endoglucanase genes and enzymes in decapods, which may ultimately assist in the design of optimal plant based crustacean aquaculture feeds.
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Crawford, Allison Clare. "Evolution and function of cellulase genes in Australian freshwater crayfish." Queensland University of Technology, 2006. http://eprints.qut.edu.au/16274/.
Full textAbstract:
The most abundant organic compound produced by plants is cellulose, however it has long been accepted that animals do not secrete the hydrolytic enzymes required for its degradation, but rely instead on cellulases produced by symbiotic microbes. The recent discovery of an endogenous cDNA transcript encoding a putative GHF9 endoglucanase in the parastacid crayfish Cherax quadricarinatus (Byrne et al., 1999) suggests that similar cellulase genes may have been inherited by a range of crustacean taxa. In this study, the evolutionary history of the C. quadricarinatus endoglucanase gene and the presence of additional GHF9 genes in other decapod species were investigated. The activity of endoglucanase and endoxylanase enzymes within several cultured decapod species were also compared. The evolutionary history of the C. quadricarinatus endoglucanase gene was assessed by comparing intron/exon structure with that of other invertebrate and plant GHF9 genes. The coding region of the gene was found to be interrupted by eleven introns ranging in size from 102-902 bp, the position of which was largely conserved in both termite and abalone GHF9 genes. These structural similarities suggest GHF9 genes in crustaceans and other invertebrate taxa share a common ancestry. In addition, two introns were observed to share similar positions in plant GHF9 genes, which indicates this enzyme class may have been present in ancient eukaryote organisms. The presence of GHF9 genes in C. quadricarinatus and various other decapod species was then explored via degenerate primer PCR. Two distinct GHF9 gene fragments were determined for C. quadricarinatus and several other Cherax and Euastacus parastacid freshwater crayfish species, and a single GHF9 gene fragment was also determined for the palaemonid freshwater prawn Macrobrachium lar. Phylogenetic analyses of these fragments confirmed the presence of two endoglucanase genes within the Parastacidae, termed EG-1 and EG-2. The duplication event that produced these two genes appears to have occurred prior to the evolution of freshwater crayfish. In addition, EG-2 genes appear to have duplicated more recently within the Cherax lineage. The presence of multiple GHF9 endoglucanase enzymes within the digestive tract of some decapod species may enable more efficient processing of cellulose substrates present in dietary plant material. Endoglucanase and endoxylanase enzyme activities were compared in several parastacid crayfish and penaeid prawn species using dye-linked substrates. Endoglucanase activity levels were higher in crayfish compared with prawn species, which corresponds with the known dietary preferences of these taxa. Endoglucanase temperature and pH profiles were found to be very similar for all species examined, with optimum activity occurring at 60°C and pH 5.0. These results suggest endoglucanase activity in penaeid prawns may also be derived from endogenous sources. Additional in vitro studies further demonstrated crayfish and prawn species liberate comparable amounts of glucose from carboxymethyl-cellulose, which indicates both taxa may utilise cellulose substrates as a source of energy. Endoxylanase temperature and pH profiles were also similar for all crayfish species examined, with optimal activity occurring at 50°C and pH 5.0. These results suggest xylanase activity in crayfish may originate from endogenous enzymes, although it is unclear whether this activity is derived from GHF9 enzymes or a different xylanase enzyme class. In contrast, no endoxylanase activity was detected in the three prawn species examined. Together, these findings suggest a wide range of decapod crustacean species may possess endogenous GHF9 endoglucanase genes and enzymes. Endoglucanases may be secreted by various decapod species in order to digest soluble or amorphous cellulose substrates present in consumed plant material. Further biochemical studies may confirm the presence and functional attributes of additional endoglucanase genes and enzymes in decapods, which may ultimately assist in the design of optimal plant based crustacean aquaculture feeds.
47
Pavasovic, Ana. "Evaluation of the nutritional requirements of redclaw crayfish, Cherax quadricarinatus." Thesis, Queensland University of Technology, 2008. https://eprints.qut.edu.au/16615/1/Ana_Pavasovic_Thesis.pdf.
Full textAbstract:
Aquaculture represents a sustainable alternative to natural fisheries for provision of high quality, animal protein. Crustaceans make a significant contribution to global aquaculture production, of which decapods are the most economically important group. Among freshwater crayfish, the genus Cherax includes several species that have emerged as important culture species. A suite of favourable biological attributes, including fast growth and an omnivorous feeding habit, have contributed to establishment of successful culture of Cherax quadricarinatus (redclaw) in many countries. Aspects of redclaw production, however, remain relatively undeveloped, in particular feed formulation. To better understand the digestive processes and nutritional requirements of redclaw, this study examined the relationship between diet composition and digestive enzyme activity, growth performance and diet digestibility coefficients.
The extent to which redclaw can efficiently utilise complex polysaccharides, such as cellulose, has been speculated on by authors who reported endogenous cellulase activity in this species. I evaluated the use of insoluble α-cellulose by redclaw, demonstrated that high dietary levels (30%) can significantly reduce the specific activity of selected digestive enzymes (amylase and cellulase), while also lowering apparent digestibility coefficients. Inclusion of α-cellulose above 12% also significantly reduced survival rate, specific growth rate and feeding efficiency in this organism which corresponds with low tolerance for insoluble fibre by other decapods. Even though redclaw possess endogenous cellulases, they appear to have only a limited capacity to utilise insoluble fibre in their diets.
Further, I assessed the impact of different nutrient profiles on digestive enzyme activity, growth and tail muscle composition in redclaw. Purified diets containing varying levels of dietary protein significantly affected activity of digestive enzymes (protease, amylase and cellulase) and the composition of the tail muscle tissue. Redclaw have a relatively low protein requirement, which was reflected here, as little significant difference was observed in growth rates and the feed conversion ratio was only significantly affected by the lowest protein diet. Manipulation of the non-protein energy component in purified diets (protein to lipid ratio) had no effect on growth performance indices in redclaw. Digestive enzyme activity (protease) was however, strongly influenced by both the amount of protein and lipid in the diet and a significant correlation was observed between protease activity and growth performance indices. The findings here, provide preliminary data for consideration of digestive enzymes such as proteases as potential growth indicators for freshwater crayfish. These enzymes are already recognised as reliable biological indicators for comparison of digestive efficiency and potential growth rate in fish. The relationship between diet composition and digestive enzyme expression observed here, stress the need for further empirical evaluation of specific ingredients in artificial diets for redclaw.
A range of single cell, plant and animal-based, agricultural products were assessed for their potential use in diets formulated for redclaw. Analysis of dietary supplements revealed that apparent digestibility of crude protein was generally higher for diets containing plant-based ingredients. A similar outcome was observed for digestibility coefficients of test ingredients. Ingredient type also had a significant effect on digestive enzyme activity. Importantly, a significant correlation was observed for enzyme activity and apparent digestibility coefficients. It appears that redclaw have the capacity to utilise nutrients from a broad range of dietary ingredients successfully including animal, single cell and in particular, plant matter in their diet.
Taken together, the results presented here demonstrate that digestive enzyme activities in redclaw are significantly influenced by diet composition. I show clearly that the ability of redclaw to utilise various nutrients (measured as digestibility coefficients) is highly correlated with digestive enzyme activity. Finally, protease activity demonstrated a potential for use as an indicator of redclaw growth performance. The data presented here will contribute to development of better and cheaper feed formulations for use in redclaw aquaculture and have broader applications to freshwater crustacean culture. In particular, the potential for use of plant-based ingredients in aqua-feeds for redclaw will contribute to a more economically and environmentally sustainable redclaw culture.
48
Pavasovic, Ana. "Evaluation of the nutritional requirements of redclaw crayfish, Cherax quadricarinatus." Queensland University of Technology, 2008. http://eprints.qut.edu.au/16615/.
Full textAbstract:
Aquaculture represents a sustainable alternative to natural fisheries for provision of high quality, animal protein. Crustaceans make a significant contribution to global aquaculture production, of which decapods are the most economically important group. Among freshwater crayfish, the genus Cherax includes several species that have emerged as important culture species. A suite of favourable biological attributes, including fast growth and an omnivorous feeding habit, have contributed to establishment of successful culture of Cherax quadricarinatus (redclaw) in many countries. Aspects of redclaw production, however, remain relatively undeveloped, in particular feed formulation. To better understand the digestive processes and nutritional requirements of redclaw, this study examined the relationship between diet composition and digestive enzyme activity, growth performance and diet digestibility coefficients. The extent to which redclaw can efficiently utilise complex polysaccharides, such as cellulose, has been speculated on by authors who reported endogenous cellulase activity in this species. I evaluated the use of insoluble α-cellulose by redclaw, demonstrated that high dietary levels (30%) can significantly reduce the specific activity of selected digestive enzymes (amylase and cellulase), while also lowering apparent digestibility coefficients. Inclusion of α-cellulose above 12% also significantly reduced survival rate, specific growth rate and feeding efficiency in this organism which corresponds with low tolerance for insoluble fibre by other decapods. Even though redclaw possess endogenous cellulases, they appear to have only a limited capacity to utilise insoluble fibre in their diets. Further, I assessed the impact of different nutrient profiles on digestive enzyme activity, growth and tail muscle composition in redclaw. Purified diets containing varying levels of dietary protein significantly affected activity of digestive enzymes (protease, amylase and cellulase) and the composition of the tail muscle tissue. Redclaw have a relatively low protein requirement, which was reflected here, as little significant difference was observed in growth rates and the feed conversion ratio was only significantly affected by the lowest protein diet. Manipulation of the non-protein energy component in purified diets (protein to lipid ratio) had no effect on growth performance indices in redclaw. Digestive enzyme activity (protease) was however, strongly influenced by both the amount of protein and lipid in the diet and a significant correlation was observed between protease activity and growth performance indices. The findings here, provide preliminary data for consideration of digestive enzymes such as proteases as potential growth indicators for freshwater crayfish. These enzymes are already recognised as reliable biological indicators for comparison of digestive efficiency and potential growth rate in fish. The relationship between diet composition and digestive enzyme expression observed here, stress the need for further empirical evaluation of specific ingredients in artificial diets for redclaw. A range of single cell, plant and animal-based, agricultural products were assessed for their potential use in diets formulated for redclaw. Analysis of dietary supplements revealed that apparent digestibility of crude protein was generally higher for diets containing plant-based ingredients. A similar outcome was observed for digestibility coefficients of test ingredients. Ingredient type also had a significant effect on digestive enzyme activity. Importantly, a significant correlation was observed for enzyme activity and apparent digestibility coefficients. It appears that redclaw have the capacity to utilise nutrients from a broad range of dietary ingredients successfully including animal, single cell and in particular, plant matter in their diet. Taken together, the results presented here demonstrate that digestive enzyme activities in redclaw are significantly influenced by diet composition. I show clearly that the ability of redclaw to utilise various nutrients (measured as digestibility coefficients) is highly correlated with digestive enzyme activity. Finally, protease activity demonstrated a potential for use as an indicator of redclaw growth performance. The data presented here will contribute to development of better and cheaper feed formulations for use in redclaw aquaculture and have broader applications to freshwater crustacean culture. In particular, the potential for use of plant-based ingredients in aqua-feeds for redclaw will contribute to a more economically and environmentally sustainable redclaw culture.
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MELOTTO, ANDREA. "ANTI-PREDATOR RESPONSES TOWARDS AN INVASIVE CRAYFISH IN AMPHIBIAN LARVAE." Doctoral thesis, Università degli Studi di Milano, 2020. http://hdl.handle.net/2434/714592.
Full textAbstract:
Invasive species pose a severe threat to native ecosystems and represent the second cause of biodiversity loss on global scale after habitat destruction.
In particular, invasive predators are major drivers of rapid population declines and local extinctions in native prey. During biotic invasions, native prey become abruptly exposed to novel predators with which they share no history of coevolution. Thus, the lack of common evolutionary history often hampers prey effective response to the novel predation pressures; native prey can both fail to recognise predators as a threat and exhibit anti-predator strategies that are inadequate. Nonetheless, mechanisms such as rapid adaptation and phenotypic plasticity can allow prey to cope with new selective pressures and drive evolutionary changes that can help native species withstanding invasive ones.
Due to their relative ecological isolation, freshwater ecosystems are particularly sensitive to invasive species impacts and likewise are most of the organisms exploiting them like amphibians; aquatic and semi-aquatic amphibians are effective indicators of freshwater habitats conservation with an excellent potential for studying the responses towards invasive species. Indeed, generally, amphibians show high level of developmental and behavioural plasticity and have relatively short life cycles, which could allow the detection of important adaptive patterns even few years after the spreading of invasive organisms.
This thesis investigated how amphibians can respond to a novel predation pressure, by assessing their modulation of anti-predator responses on multiple traits (i.e. behavioural morphological, life-history). In particular, I aimed to shed light on (i) the role of phenotypic plasticity in mediating the expression of anti-predator responses towards invasive predators; (ii) how novel predation pressures can interact with extant selective forces and foster rapid adaptation in native prey; and (iii) which evolutionary mechanisms are involved in allowing predator recognition by naïve prey.
To this extent, I evaluated the expression of anti-predator responses in amphibian larvae towards the American red swamp crayfish (Procambarus clarkii). This widespread crayfish is listed among the 100 worst invasive alien species, and is a voracious predator of amphibian eggs and larvae, often associated to strong declines of amphibian populations outside its native range.
In brief, the research consisted in two main experimental studies, the first of which focused on developmental shifts of a single anuran species, while the second one assessed behavioural responses to the invasive crayfish across the amphibian community of Northern Italy.
In the first study, I exposed tadpoles of an endemic frog (Rana latastei) from recently invaded (10- 15 years) and uninvaded populations to the non-lethal presence of the invasive crayfish during their ontogenesis. Tadpoles from invaded populations showed rapid adaptation in life-history traits (reduced development time), and this caused the disappearance of pre-existing adaptive divergence between R. latastei populations exploiting environments with different climatic regimes. However, even if early metamorphosis in invaded populations probably has great advantages as it reduces exposure to crayfish predation, this shift can produce potential carry-over effects on post-metamorphic traits. Indeed, the observed development acceleration was not without a cost, as faster-developing froglets were smaller and displayed poorer jumping performances.
Besides, experimental exposure to the invasive crayfish revealed tadpoles were also able to modulate both their development time and morphological traits through phenotypic plasticity. An acceleration in development time was observed even in exposed tadpoles. Moreover, tadpoles reared in presence of P. clarkii showed shift in body shape together with an increase in tail muscle size, which is a trait associated to faster swim and can increase escape from predators. By contrast, tadpole behaviour was not influenced nor by origin (invaded or not invaded populations) neither by crayfish exposure.
The second study was performed on several species composing Northern Italy amphibian community (five urodele and eight anuran species); for each species I assessed how different stimuli mediated novel predator recognition and elicited the expression of anti-predator responses in naïve species. To this extent, I evaluated multiple larval behavioural traits after brief non-lethal exposure to crayfish-released cues (four treatments: visual cues, chemical cues, contemporary exposure to both cues and control). Moreover, I tested if these responses were influenced by the coevolutionary history some of these species shared with a similar native predator, the European crayfish (Austropotamobius italicus). I showed that all species altered their behaviour when exposed to the invasive crayfish while the modality and intensity of response was highly heterogeneous. However, almost all behavioural responses were driven by visual cues, while chemical cues elicited feeble and contrasting outcomes. Finally, I found no support for a coevolutionary history hypothesis between native amphibians and native crayfish, as responses to the invasive predator were not affected by species coexistence with native crayfish. Instead, behavioural responses observed in naïve species was likely elicited by recognition of general predator traits (e.g. an approaching large shape).
The broad implication of my thesis is that amphibian facing invasive predators can both exhibit rapid adaptation to the novel selective pressures and modulate their developmental traits through phenotypic plasticity. Moreover, the expression of these responses is context-dependent and can highly vary in relation to the experienced conditions and across species. For instance, varying typology of risk exposure can produce marked difference in anti-predator response (e.g. activation of short-term behavioural response vs long-term morphological responses). Future studies assessing responses to invasive predators should evaluate multiple traits and carefully consider risk exposure conditions when planning experiments. Finally, the expression of anti-predatory responses of native amphibians, and particularly their effectiveness towards invasive predators, need further extensive investigation, and future conservation plans should take into account both species trends and their responsiveness to global change stressors.
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Schrimpf, Anne [Verfasser]. "DNA-based methods for freshwater biodiversity conservation - phylogeographic analysis of noble crayfish (Astacus astacus) and new insights into the distribution of crayfish plague / Anne Schrimpf." Landau : Universitätsbibliothek Landau, 2013. http://d-nb.info/1033286303/34.
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