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1
Azzopardi, P. J. "Visually-mediated behaviour of the perch, Perca fluviatilis L." Thesis, University of Manchester, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.375058.
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Linløkken, Arne. "Population ecology of perch (Perca fluviatilis) in boreal lakes." Doctoral thesis, Karlstads universitet, Avdelningen för biologi, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:kau:diva-1645.
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I studied the effects of temperature, pH, competition and predation on Eurasian perch (Perca fluviatilis) in 30 lakes in Norway during 1981-2001. The study lakes were situated in two different areas in southern Norway; four lakes in Aust-Agder county in southernmost Norway were explored during 1981-1984 and 26 lakes in Hedmark county in south-eastern Norway were investigated during 1992-2001. The study lakes varied considerably in pH, temperature, fish species composition, and perch abundance and size composition. In addition to field surveys, behavioural studies of perch were conducted at Karlstad University in 2006-2007. The field studies revealed that temperature affected recruitment of perch as strong year-classes of perch generally occurred in summers with high temperatures. Temperature also affected perch behaviour as indicated by the low gillnet catches (CPUE) of perch atlow temperature. This effect on CPUE was also supported by results from the aquaria experiments, where swimming and feeding activity of perch was low at low temperature. In a study of four lakes, growth was positively related to temperature in the lake with an allopatric perch population, but not in three lakes where perch occurred sympatrically with roach. pH also affected recruitment. In the four lakes in Aust-Agder, one strong year-class of perch occurred in all lakes in a year with especially high pH in spring and early summer. Adult mortality was also affected by pH, as old perch were less abundant in lakes with late spring pH=5.5-5.8 than in lakes with pH<5.5 and pH>5.8. The size and growth of adult perch were negatively affected by low pH, whereas abundance of large, potentially predatory perch was positively related to pH. The field studies indicated that roach influence perch populations. When coexisting with roach, perch were mainly littoral. In lakes where roach dominated (by number), there was no growth – temperature correlation, but there was such a correlation in lakes without roach. In lakes with sympatric roach, age-specific weight of perch and the growth of 2+ perch were negatively related to the proportion of roach in the gillnet catches. In the aquaria experiments, swimming and feeding activity of perch were lower than that of roach at all temperatures tested, and the difference was most pronounced at 4 and 8 °C. The aquaria experiments indicated that perch had a lower feeding efficiency and that they generally occupied positions closer to the bottom than roach.
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Strand, Åsa. "The growth and energetics of perch (Perca fluviatilis L.) in intensive culture." Umeå : Dept. of Wildlife, Fish, and Environmental Studies, Swedish University of Agricultural Sciences, 2009. http://epsilon.slu.se/200971.pdf.
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Sandberg, Linda. "Movement of the Eurasian perch (Perca fluviatilis) : Individual responses to abiotic factors." Thesis, Umeå universitet, Institutionen för ekologi, miljö och geovetenskap, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-172751.
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Movement increases the probability for an individual to find food resources, but also increase the metabolic costs and exposure to predators. Hence, swimming behavior of fish is strongly coupled to fitness. Even though swimming activity has been studied in numerous laboratory settings, less is known about in situ activity and its dependence on abiotic factors (temperature, light conditions and barometric pressure). In this study I hypothesized that the activity increases with 1) increasing temperature and decrease with 2) barometric pressure variability and 3) average light conditions (h/day). In order to test the universality of the three hypotheses I also searched for size dependent effects. Fish activity (km/day) was measured in three lakes on individual fish (N=14-21 per lake) using acoustic telemetry providing tracking of fish at a time resolution from seconds to hours. A positive correlation between temperature and swimming activity in line with my first hypothesis was only observed in one of the lakes. The activity decreased with increased variability in barometric pressure in two of the lakes, a finding supporting my second hypothesis. Meanwhile increased light conditions (h/day) decreased activity in one of the lakes, as predicted by my third hypothesis. Nevertheless, none of my hypotheses were valid in all three of the lakes and perch reacted differently to the abiotic factors. One of the possible explanations for this is the importance of size differences as I noticed that the swimming activity differed between bigger and smaller individuals. My findings suggest that not only the temperature, barometric pressure and light conditions alone predict the activity in perch, but also the fish individual size, predation and the metabolic costs linked to thermoregulation.
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Heibo, Erik. "Life-history variation and age at maturity in Eurasian Perch (Perca fluviatilis L.) /." Umeå : Dept. of Aquaculture, Swedish Univ. of Agricultural Sciences, 2003. http://epsilon.slu.se/s290.pdf.
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Montgomery, Caron R. "The ecology of the perch (Perca fluviatilis L.) of lough Neagh, Northern Ireland." Thesis, University of Ulster, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.293887.
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Robak, Enbratt Emelie. "Eurasian perch (Perca fluviatilis) is negatively affected by lake browning in southern Sweden." Thesis, Högskolan i Halmstad, Akademin för ekonomi, teknik och naturvetenskap, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:hh:diva-42381.
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Climate change and human land use leads to browning of waters with decreased visual conditions. This impacts the fish community via changes in foraging ability and food chain efficiency. There are indications that brownification leads to decreased body size of the Eurasian perch (Perca fluviatilis) and that roach (Rutilus rutilus) are favoured over perch in brown lakes since roach is less dependent on its eyesight when foraging. The aim with this project is to examine how browning impacts the fish community in lakes in the south of Sweden and if browning reduces the size of perch in relation to their age. Data on water colour and length-at-age for 1+ and 5+ perch as well as the number of perch and roach captured was collected from 20 lakes. The data was examined using linear regression and paired samples T-test in SPSS. The results show that browning does reduce the body size of perch. Perch is smaller in relation to their age in brown lakes. There was however no evidence indicating that roach is favoured over perch in brown lakes, but there was a difference between the number of 1+ and 5+ perch caught in relation to roach. The perch: roach ration decreased for older fish (from 1+ to 5+) indicating that there is a difference in survival rate. Survival rate of perch was however not dependent on water colour or TOC. This shows that climate change and increased browning could result in changes of the fish community and size structure of fish.
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Johansson, Karl Magnus. "Fredningseffekter och rekryteringsproblem hos abborre (Perca fluviatilis) i Stockholms skärgård." Thesis, Högskolan på Gotland, Institutionen för kultur, energi och miljö, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:hgo:diva-853.
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Effects of fishery closure on perch was detected as female perch was on average 5 cm longer in closed areas compared to non-closed areas. This could be a result of larger individuals surviving as an effect of reduced fishing. No effect was detected on the reproduction rate of YOY (young of the year) perch. A zooplankton survey revealed less amounts of the most important plankton groups for YOY perch in areas with failed reproduction, though the difference was statistically insignificant. The distribution of YOY perch and YOY/adult stickleback differed completely in this study with no area where the two species are both present. It is sketchy to draw any conclusions from this data but it remains a field for further investigation. The reproduction problem is concentrated to the outer parts of the archipelago which confirms previous studies of the geographic extension.
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Pilinkovskij, Andrej. "Pūgžlių (Gymnocephalus cernuus) ir ešerių (Perca fluviatilis) mityba Dusios ežere." Master's thesis, Lithuanian Academic Libraries Network (LABT), 2014. http://vddb.library.lt/obj/LT-eLABa-0001:E.02~2009~D_20140626_190748-78566.
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Dusios ežere 2008 metų ichtiologinių tyrimų metu sugautos 6 žuvų rūšys: ešerys, pūgžlys, stinta, lydeka, kuoja ir paprastoji aukšlė. Žuvų bendrijos branduolio rūšinė sudėtis ir toliau išlieka tokia pati – pūgžlys ir ešerys. Tačiau žymiai pakito šių rūšių santykinė biomasė – pūgžlio sumažėjo 1,7 karto ir dabar sudaro 27,6%, o ešerio padidėjo 1,8 karto ir sudaro 45,3%. Tiriant skirtingų amžinių grupių pūgžlių mitybą buvo nustatyta, kad Gammaridae ir Chironomidae šeimos atstovai yra visų amžinių grupių pagrindinis maistas. Tiriant skirtingų amžinių grupių ešerių mitybą buvo nustatyta, kad Gammaridae ir Chironomidae šeimos atstovai yra 1+ - 5+ amžinių grupių pagrindinis maistas, o Pisces yra vyresnių už 5+ amžinę grupę pagrindinis maistas. Ešerių mityboje pūgžlių aptikta nebuvo.In the Dusia Lake in 2008 ichtiology studies caught 6 species of fish: perch, ruff, smelt, pike, roach and bleak simple. Fish species composition of the nucleus remains the same - ruff and perch. However, a significant change in the relative biomass of those species - ruff decreased 1.7 times and now represents 27.6%, and the perch has increased 1.8 times and is 45.3%. In the case of the different groups ever ruff diet, it was found that Gammaridae and Chironomidae family of representatives of all the basic food groups ever. In the case of the different groups ever perch diet was found that the Gammaridae and Chironomidae family is represented by 1 + - 5 + forever the main food groups, while Pisces is older than 5 + eternal group of the main food. Perch nutrition ruff was not detected.
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Gunnarsson, Thor. "Morphology and physiology of horizontal cells in the retina of the perch (Perca fluviatilis L.)." Thesis, Durham University, 1985. http://etheses.dur.ac.uk/7486/.
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Horizontal cells of the perch retina were studied with morphological and physiological techniques. Three types of cone horizontal cells were observed in Golgi preparations and they were called HI, H2, and H3 type cells, according to their morphological characteristics. Analysis of cone-horizontal cell contacts, revealed that HI cells contact red sensitive twin cones and green sensitive single cones, H2 cells contact red sensitive twin cones exclusively, and H3 cells contact exclusively green sensitive single cones. Inter connections of cones by basal processes were also examined; single cone basal processes were found to contact twin cone pedicles, and twin cone basal processes to contact other twin cone pedicles. The spectral sensitivity and spatial organization of horizontal cells were analysed by intracellular recordings. Two types of horizontal cell responses were observed; L-type responses that hyper polarized to light stimuli of all wavelengths, and R/G C-type responses that depolarized to red and hyperpolarized to green stimuli. Correlation of anatomical and morphological results suggests that HI and H2 cells generate L-type responses, and H3 cells generate R/G C-type responses. The R/G cells are hyperpolarized by signals from the green (P5352) sensitive cones and depolarized by a far red (650-670 nm) mechanism. Compared with the red cone pigment (P6I52), the L-type horizontal cell spectral sensitivity curve is narrow and with maximum (650 nm) displaced towards the red end of the spectrum (a pseudopigment spectral sensitivity curve), suggesting that an antagonistic interaction occurs between the two cone types, generating the horizontal cell spectral sensitivity function.
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Peter, Magali. "Profil et métabolisme des acides gras dans les tissus de la perche comme Perca fluviatilis L." Thesis, Vandoeuvre-les-Nancy, INPL, 2008. http://www.theses.fr/2008INPL025N/document.
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La perche commune, Perca fluviatilis L. est un poisson maigre (moins de 2% de lipides dans le filet) mais dont les teneurs en acides gras polyinsaturés de la famille n-3 (AGPIn-3) et principalement en acide docosahexaènoque (DHA) sont très élevées (40% des AG totaux). L’objectif de ce travail est d’étudier les facteurs qui influent sur le métabolisme lipidique chez la perche et qui assurent ces taux élevés de DHA. Les hypothèses testées qui permettraient d’expliquer les fortes teneurs en DHA sont une incorporation préférentielle de cet AG ainsi qu’une capacité, typique des poissons d’eau douce, à bioconvertir le 18:3n-3 présent dans l’alimentation en AGPI n-3 supérieur, EPA et DHA. Pour tester ces hypothèses nous avons mis en place trois expérimentations. Dans un premier temps, nous avons caractérisé les lipides des différents tissus impliqués dans le métabolisme lipidique en observant leurs teneurs en lipides totaux, neutres et polaires et leur composition en acides gras. Dans un deuxième temps nous avons déterminé et hiérarchisé les facteurs ayant un effet sur la teneur en lipides et la composition en AG en utilisant un plan d’expérience multifactorielle. Enfin, nous avons étudié plus particulièrement l’effet de la composition en acides gras de la source alimentaire sur la composition en AGPI n-3 des tissus, l’activité enzymatique et l’expression des gènes codant pour les enzymes impliquées dans la bioconversion des AG. Le génome de la perche n’étant pas séquencé pour l’instant, le premier travail a été de mettre au point les protocoles de dosage d’activité enzymatique et d’expression génique chez cette espèce. La qualité nutritionnelle de la perche a été vérifiée, avec la mise en évidence de taux élevés de DHA dans tous les tissus. Dans le muscle la teneur en lipides est stable. La teneur en AGPI est élevée (40-60% des AG totaux), avec des teneurs élevées en DHA (35-45% des AG totaux) qui est l’AG majoritaire dans ce tissu. La teneur en lipides du foie et du tissu adipeux est variable en fonction de l’aliment. Le tissu adipeux est le lieu de stockage de l’énergie, il contient entre 85-90% de lipides dont 30-50% sont sous forme mono-insaturée, principalement représentés par le 18:1n-9. Le foie a une composition en AG intermédiaire entre celle du muscle et celle du tissu adipeux, le DHA étant là aussi l’AG majoritaire. Nos résultats ont complété ceux de la littérature en donnant des informations sur la répartition et la teneur en lipides neutres et polaires des tissus (Muscle LN/LP= 50/50 ; Foie LN/LP= 60/40 ; Tissu adipeux : LN/LP= 90/10), ainsi que sur leur profil en acides gras (les lipides polaires sont composés majoritairement d’AGPI alors que les lipides neutres sont plus riches en acides gras saturés). Ils ont permis de mettre en évidence une spécificité du profil en acides gras en fonction du tissu ou du type de lipides. L’hypothèse de bioconversion des AGPI a été vérifiée puisque la delta 6 désaturase a été détectée dans le foie, l’intestin, le cerveau. De plus, son activité a été mise en évidence dans le foie. L’hypothèse d’incorporation préférentielle de certains acides gras a également été vérifiée, avec une incorporation préférentielle d’AGMI dans le tissu adipeux et d’AGPI dans le filet et le foie. Concernant l’effet des facteurs étudiés, nos résultats ont montré qu’il existe un déterminisme différent en fonction de l’acide gras.. La nature des lipides alimentaires est le facteur le plus important, il a un effet direct ou en interaction avec d’autres facteurs sur le profil en AG des tissus. Nos résultats ont montré que si l’alimentation est le facteur principal de variation, dans des conditions de croissance limitée, sur un poisson de taille commerciale, une teneur de 3% de DHA et de 2% d’EPA dans l’aliment est suffisante chez la perche pour obtenir une composition en acides gras du filet de bonne qualité pour le consommateur avec une bioconversion des AGPI n-3 limitéePerca fluviatilis L. (Eurasian perch) is characterized by a low intramuscular amount of lipids (<2%) and a high poly-unsatured fatty acid (PUFA) content. Docosahexaenoic acid (DHA, 22:6n-3) is present in a high proportion (40% of total fatty acid). The aims of this work are twofold: first to analyse the factors that could influence the lipid metabolism of Perca fluviatilis L. and second to identify factors that could explain the elevated contents of DHA in this fish. Assumptions, which have been tested to explain the high concentration of DHA, are a selective incorporation of this fatty acid and the ability of this fish to transform 18:3n-3 present in the diet into higher PUFA n-3, EPA and DHA; typical capacity of freshwater fish (bioconversion assumption). Three experiments have been conducted to test these assumptions. First, we described lipid composition of the different tissues, which play a role in lipid metabolism, by distinguishing total, neutral and polar lipids. Second, we identified and classified the factors influencing the lipid content and fatty acid composition by using a multifactorial approach. Third, we analysed the effect of diet fatty acid composition on PUFA n-3 tissues composition, enzymatic activity and genes expression, which code for enzymes implicated in fatty acid bioconversion. As Perca fluviatilis L. genome is not sequenced for the moment, the first work was to construct experiments for dosing enzymatic activity and gene expression in this species. Concentration of DHA was elevated in all the tissues we analysed, showing the good nutritional quality of Perca fluviatilis L. In the fillet, lipid content was stable. PUFA content was high (40-60% of total fatty acid), with elevated contents in DHA (35-45% of total fatty acid), which was the main fatty acid of this tissue. Lipid content in the liver and the fat tissue was variable according to the type of food. Adipose tissue, that is the lipid storage tissue in this species, was composed of 85-90% of lipid, of which 30-50% are mono-unsatured fatty acids (MUFA), mainly 18:1n-9. Liver fatty acid composition presented characteristics in an intermediate position between fatty acid composition of the fillet and the adipose tissue, but DHA was still the most abundant fatty acid. Our results were in accordance with literature. They added informations on the distribution and the concentration in neutral and polar lipids (NL and PL) of the tissues we studied (fillet NL/PL=50/50; Liver: NL/PL=60/40; adipose tissue: NL/PL=90/10), and on their composition in fatty acid (polar lipids are mainly composed of PUFA whereas neutral lipids are richer in saturated fat acids). Our results showed that the profile in fat acid depended on the tissue and the type of lipids. Our assumption of the ability of Perca fluviatilis L. to transform PUFA was verified because we were able to detect delta 6 desaturase in the liver, intestine, and brain. Moreover, the activity of this enzyme was put in evidence in the liver. Our assumption of selective incorporation of some fatty acids was also verified, MUFA being preferentially absorbed in the adipose tissue and PUFA in the fillet and the liver. Regarding the effect of factors we studied, our results showed that a differential determinism existed according to the type of fatty acid. The nature of lipids contained in the diet was the most important factor. This factor could influence the profile of fatty acid in the tissues through a direct effect or in interaction with other factors. Although the diet is the main factor of variation, our results showed that under condition of limited growth and for a fish with a commercial size, a content of 3% of DHA and 2% of EPA in the diet was sufficient to obtain, in the fillet, a composition in fatty acids of good quality for consumers with a limited bioconversion of PUFA
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Andersson, Magnus. "Selective predation by perch (Perca fluviatilis) on a freshwater isopod, in two macrophyte substrates." Thesis, Linköpings universitet, Ekologi, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-58018.
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Recent studies show that populations of the freshwater isopod Asellus aquaticus L. can rapidly become locally differentiated when submerged stonewort (Chara spp.) vegetation expands in lakes. In the novel Chara habitat, isopods become lighter pigmented and smaller than in the ancestral reed stands. In this study, I used laboratory experiments to investigate if selective predation by fish could be a possible explanation for these phenotypic changes. Predation from fish is generally considered to be a strong selective force on macroinvertebrate traits. In the first experiment I measured perch (Perca fluviatilis L.) handling time for three size classes of Asellus to see which size of those that would be the most profitable to feed upon. No difference in handling time was detected between prey sizes, hence the largest size would be the most beneficial to feed upon. In a second experiment I let perch feed on a mixture of Asellus phenotypes in aquaria manipulated to mimic the substrates in either the Chara or the reed habitats. Remaining isopods were significantly smaller and lighter pigmented in the fish aquaria than in the controls, showing that the perch preferred to feed on large and dark individuals. In the Chara habitat, selection on isopod pigmentation was according to what could be expected from background matching, but in the reed habitat selection was quite the opposite. These results support the hypothesis that predation from fish is a strong selective force behind the rapid local adaptation seen in Asellus populations in the novel Chara habitat.
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Staffan, Fia. "Food competition and its relation to aquaculture in Juvenile Perca fluviatilis /." Umeå : Dept. of Aquaculture, Swedish Univ. of Agricultural Sciences, 2004. http://epsilon.slu.se/s329.pdf.
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Hjältén, Alexander. "Storspiggens (Gasterosteus aculeatus) påverkan på abborryngel (Perca fluviatilis) via storleksberoende predation." Thesis, Umeå universitet, Institutionen för ekologi, miljö och geovetenskap, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-118551.
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The costal populations of perch (Perca fluviatilis) in some parts of the Baltic Sea have been in decline for about two decades. Recruitment failure in the early larval stages has been put forward as a possible cause and the decline has also been suggested to coincide with increases in three-pined stickleback (Gasterosteus aculeatus) densities. The aim of this study was to study the effects of growth and survival of newly hatched perch larvae in the presence of the three-pined stickleback, and if possible determine the main mechanism behind any negative effects the perch may suffer under such conditions. Using large scale experimental ponds as a controlled habitat, an experiment was conducted where perch larvae were being exposed to sticklebacks under four different stages of their development. Results showed that the three- spine stickleback can have a strong negative effect on the survival of young perch. This effect was strongest in the earliest stage of perch development and decreased as they grew bigger. The zooplankton densities didn't differ between the controls and stickleback treatments, suggesting that the young perch didn't suffer from food limitation. Instead predation was identified as the main mechanism behind the high mortality. The results of this study highlight the potential danger of the observed patterns of decreasing predator populations in conjunction with increasing populations of smaller prey species in the Baltic Sea.
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Bublys, Kasparas. "Diet variability in Eurasian perch (Perca fluviatilis) as a response to environmental variables along a latitudinal gradient." Thesis, Uppsala universitet, Institutionen för biologisk grundutbildning, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-365794.
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Climate change is expected to have a profound impact on freshwater fish communities, especially at higher latitudes. In this study I investigated potential effects of climate change on the niche structure of Eurasian perch (Perca fluviatilis) by looking at their diet across a latitudinal gradient and at varying light climate. Dietary niche width of Eurasian perch did not differ significantly between boreal and temperate latitudes. Additionally, no significant difference in the prevalence of specialist individuals was found along the latitudinal gradient and water transparency levels. Habitat was the main factor that significantly affected niche width and level of specialization with both being significantly higher in the littoral habitat. Taken together my results suggest that climate change might indirectly affect niche patterns by altering fish densities through changes in productivity resulting in niche and specialization variation among habitats.
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VLAVONOU, RAPHAEL Moreteau Jean-Claude. "ELEVAGE EXPERIMENTAL DE LA PERCHE PERCA FLUVIATILIS L. : DEVELOPPEMENT LARVAIRE ET CROISSANCE /." [S.l.] : [s.n.], 1996. ftp://ftp.scd.univ-metz.fr/pub/Theses/1996/Sourou_Vlavonou.SMZ9656_1.pdf.
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Vlavonou, Raphaël Sourou. "Elevage expérimental de la perche Perca fluviatilis L. : développement larvaire et croissance." Metz, 1996. http://docnum.univ-lorraine.fr/public/UPV-M/Theses/1996/Sourou_Vlavonou.SMZ9656_1.pdf.
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Des embryons de perche sont récoltés en milieu naturel et incubés en structures hors sol. Les larves sont nourries avec artemia. A l'éclosion, les systèmes visuel, respiratoire, digestif, et urinaire de la perche ne sont pas développés. La rétine de l'œil, de type pur cône à l'éclosion, présente quelques doublets de cônes à l’âge de trois semaines ; les bâtonnets apparaissent à partir de l’âge de quatre semaines. Le système branchial, réduit à une simple baguette cartilagineuse à l'éclosion, compte huit à dix lamelles secondaires à l’âge de trois semaines. La vessie natatoire, non fonctionnelle à l'éclosion, est remplie d'air atmosphérique dès l’âge de deux jours. Le tube digestif, simple et rectiligne à l'éclosion, se développe progressivement avec différenciation des trois régions. La résorption de la vésicule vitelline, observée dès l’âge de deux jours est complète à l’âge de deux semaines. Le rein, limité à un pronephros à l'éclosion, apparait dès l’âge de trois semaines, comme un mesonephros glomerule avec la structure du rein de la perche adulte. Le squelette, entièrement cartilagineux à l'éclosion, commence par s'ossifier au stade de trois semaines. A cet âge, on note l'apparition des trois coeca pyloriques. L'étude zootechnique de l'élevage larvaire met en lumière la nécessité d'un milieu renouvelé. Les larves n'acceptent pas l'aliment artificiel. Les nauplii d'artemia constituent une excellente nourriture dès l’âge de deux jours. Les larves atteignent une longueur totale moyenne de douze mm avec une survie élevée à l’âge de deux semaines. A partir d'une longueur totale de seize mm, les alevins peuvent être initiés pour la prise d'aliment artificiel avec une survie élevée. Des perches produites extensivement en étang, sont également sevrées avec des taux de survie comparables lorsque leur taille moyenne ne dépassé pas cent mm. La survie est plus faible pour des perches plus grandes. Le tri sépare les perches de même âge en différents lots qui n'ont pas au même moment, la même vitesse de croissance. L'hétérogénéité des tailles au sein d'une population de perches issues d'une même ponte, s'explique par un effet de dominance. L'action de la température n'est pas significative sur la croissance des juvéniles lorsque les poissons sont élevés à température constante dans la gamme thermique de croissance optimale. Au cours de leur développement, la croissance des perches s'accorde avec un modèle exponentiel. La vitesse de croissance en masse peut être prédite grâce a un modèle qui dépend de la masse initiale et de l'indice de conversion de l'aliment artificiel. Il présente l'intérêt de faciliter la gestion des stocks en élevage. Des perches aptes au filetage, peuvent être produites intensivement en seize mois, à partir des larves fraîchement éclosesEmbryos of perch are harvested from ponds and incubated in laboratory. Larvae are fed successfully with artemia nauplii. About two days after hatching, the gas bladder is filled with atmospheric air. Larval development study shows that larvae are not fully developped at hatching. Yolk sac entire resorption is completed at two weeks old. A week later, there are significant changes : twin cones appear in the retina which was pure cone at hatching; numerous gill lamellae are present ; the pronephros is replaced by a mesonephros with an adult kidney structure. The digestive tract simple and rectilinear at hatching, is curly and more developped with the presence of three pyloric coeca. Larval rearing tests demonstrate the necessity of a recirculating system. At larval stage, perch do not accept artificial diet. They reach twelve millimetres at two weeks old. Juveniles can be weaned successfully from a size of sixteen millimetres. Perch harvested from ponds can also be successfully weaned if their size is not over one hundred millimetres. Above this size, survival rate is lower. Grading allows the separation of perch from the same strand into groups of different growth rates. The body weight heterogeneity among perch population could be explained by the dominance effect. The effect of temperature is not significant on growth when perch are raised at constant temperature in the optimal range. Perch growth is described by exponential models. A prediction of the growth rate in weight can be performed using two variables : initial body weight and the diet conversion index. From larval stage, perch of marketable size can be produced intensively in sixteen months
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Larsson, Magnus. "Impact of terrestrial organic matter on fish community : Effects on growth and biomass of perch in small lakes." Thesis, Umeå universitet, Institutionen för ekologi, miljö och geovetenskap, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-101637.
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The aim of this study was investigate if increasing total organic carbon (TOC) affects the growth rate and biomass of perch (Perca fluviatilis) and biomass of roach (Rutilus rutilus). The ongoing climate change affects the climate by increasing annual mean temperature and precipitation. The runoff to surface waters will increase, which also has the consequence that the export of terrestrial organic matter (TOM) and nutrients to surface waters will increase. Increasing of TOM into the surface waters make it darker, i.e. brownification of the water. This brownification of surface water affects the amount of available light for benthic algae causing the benthic primary production to decrease. As the benthic primary production decreases also whole lake ecosystem productivity decreases. The impact on fish biomass and production of fish were studied in five small lakes in Sweden. Lake morphology, water chemistry and fish community characteristics were sampled. A subset of perch from the catch was selected to determine age and growth. Data from age determination was then used to calculate the size dependent growth and production of perch in each lake. Total fish biomass and biomass of perch and roach was negatively affected by TOC and yearly biomass production of perch was lower in lakes with higher TOC. Thus, climate change may at least in small forest lakes lead to lower production and biomass of fish in the future.
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Gusén, Anna. "Environmental variation and phenotypic plasticity : The effect of water visibility on body pigmentation in perch (Perca fluviatilis L.)." Thesis, Uppsala universitet, Institutionen för biologisk grundutbildning, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-136956.
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Phenotypic plasticity is defined as an organism’s ability to express differentphenotypes depending on the environment. Predation is one of the key forces inecology and can indirectly cause a change of the phenotype in fish populations.Pigmentation change in order to match the background is one type of camouflage usedin fish and other organisms. Moreover, pigmentation might depend on environmentalconditions such as turbidity and water colour that affect the light spectrum and thusthe visibility in the water. The phenotypic variation in body pigmentation of perch(Perca fluviatilis L.) has rarely been studied to this date. In this study, I examined ifbody pigmentation of perch varied between different environments and betweenstructurally different habitats (littoral/pelagic). I tested long-term (phenotypicplasticity) and short-term (physiological-behavioural) changes in pigmentation byusing long-term pre-treatments and short-term aquarium experiments. Differences instructurally-diverse habitats were investigated in an extensive field study.Furthermore, experimental results were compared to data from the field. The resultsshow that pigmentation is determined by environmental factors, such as water colouror turbidity, and by structural complexity. Since fishes adapted their pigmentation totheir visual environment, pigmentation is likely used as predator avoidancemechanism in perch. Moreover, it was demonstrated that the environmentally-inducedpigmentation pattern determines the magnitude of short-term pigmentation in perch.
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Olofsson, Martin. "The influence of the cyanobacterium Nodularia spumigena on the growth of perch (Perca fluviatilis)." Thesis, Högskolan i Kalmar, Naturvetenskapliga institutionen, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:hik:diva-2318.
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Nodularin (NODLN) is a pentapeptide produced by the filamentous cyanobacterium Nodularia spumigena that is a bloom-forming species in the Baltic Sea. NODLN is an intracellular hepatotoxin, which can have a negative effect on aquatic life including fish. Toxins are released into the water when cells are lysing, e.g. during a decaying bloom. N. spumigena filaments have previously been shown to have a negative effect on perch egg development and perch larval survival. Coastal fish such as perch (Perca fluviatilis) have suffered from recruitment problems in the Baltic Sea the last decades. However, little is known about the impact of toxic cyanobacteria on juvenile perch. In the autumn of 2007, 1+ perch were exposed, during 29 days to either whole live cells (WC) or a crude extract (CE) of broken N. spumigena cells. Chlorophyll a concentrations in the aquaria were 50 µg L -1. Perch were fed chironomidae larvae twice a day. Unexposed perch either fed (CoF) or without food (Co) served as controls. Length and weight of perch were measured at onset and termination of experiment. NODLN content was measured in N. spumigena filaments, crude extract and perch liver samples using liquid chromatography-mass spectrometry (LC-MS). Total lipids (TL) were extracted and quantified from whole-body lyophilised perch excluding livers. No significant differences for length and weight of perch were found between treatments and fed control. NODLN was detected in the crude extract samples, while no NODLN was detected in the perch livers. Moreover TL determination revealed no significant differences between treatments and fed control. Nodularia spumigena did not affect perch in this experiment, probably due to that the critical period of the first year for the perch was exceeded. Therefore, 1+ perch was not as susceptible to the cyanobacterium as eggs, larvae and younger juveniles of fish found in the literature. Perch liver did not contain NODLN, thus either the toxin was detoxicated with no recorded energetic cost or it was not ingested. The variables studied here did not show any effects of NODLN. However, other chemical methods such as enzymatic activity may disclose effects of NODLN.
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Flesch, Anne. "Biologie de la perche (Perca fluviatilis) dans le réservoir du Mirgenbach (Cattenom, Moselle)." Metz, 1994. http://docnum.univ-lorraine.fr/public/UPV-M/Theses/1994/Flesch.Anne.SMZ9454.pdf.
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Le lac-réservoir du Mirgenbach, créé par pompage des eaux de la rivière Moselle en 1985, constitue une réserve de sécurité et un milieu tampon pour la centrale électronucléaire de Cattenom (Moselle, nord-est de la France). Ce réservoir, de 20 mètres de profondeur maximale, se caractérise par ses eaux échauffées et par l'absence de stratification thermique. L'étude s'inscrit dans l'analyse du fonctionnement écologique de cette retenue. Elle contribue à la connaissance, d'une part du peuplement ichtyologique (composition et évolution), et d'autre part de la démographie de l'espèce initialement dominante, la perche (perca fluviatilis). De 1987 à 1991, différentes techniques de capture passives et actives sont employées. Les filets maillants utilisés sont des filets horizontaux ou des filets verticaux qui échantillonnent dans l'ensemble de la colonne d'eau. Les séries de filets verticaux sont immergées en des stations au cours de campagnes reparties sur un cycle annuel. Au terme de cette étude, parmi les différents engins de capture employés, les filets maillants verticaux se révèlent être le meilleur outil de sondage passif pour l'étude de la démographie de la perche. L'exploitation des captures au moyen de ces différentes techniques de pêche permet de connaitre la distribution spatio-temporelle du peuplement dans le lac-réservoir. Au total, 18 espèces de poissons sont recensées avec une très nette dominance de la perche (perca fluviatilis) au début de l'étude, ensuite associée au gardon (rutilus rutilus) et à la brème commune (abramis brama). Grace à une analyse multivariée effectuée sur les captures issues des filets maillants verticaux, les résultats permettent de distinguer plusieurs groupes de stations littorales et pélagiques se caractérisant par la structure de leur peuplement. Les perches échantillonnées au moyen des filets maillants traditionnels ou verticaux ainsi qu’à la pêche à la ligne permettent de connaitre la sélectivité par engin et d'étudier l'évolution de la structure démographique. Il est noté sur ces années consécutives un déclin des captures de perche dont les causes sont anthropiques ou environnementales. La répartition saisonnière de l'espèce au sein de la masse d'eau est décrite au cours d'un cycle annuel avec des filets maillants verticaux. Les plus fortes prises de ce carnassier sont obtenues en période estivale, à l'exception d'une station de rive proche d'une frayère avant la reproduction. La distribution verticale de l'espèce varie selon la bathymétrie. Les perches sont surtout présentes au fond des stations les plus littorales et reparties dans la colonne d'eau dans les stations pélagiques. L'étude de la reproduction de la perche repose principalement sur l'utilisation d'indices pondéraux et de stades de maturité. L’âge est identifié grâce à l'application des méthodes scalimétriques et operculométriques. Les deux structures osseuses correspondantes sont exploitables indifféremment pour décrire la croissance de la perche. La reproduction de perca fluviatilis se déroule de mi-mars à mi-avril dans le réservoir du Mirgenbach. Pour certains individus, le frai débute des fin février ; la période de ponte est décalée précocement environ d'un mois par rapport aux autres étangs de la région Lorraine. Les males sont matures à 1 an et les femelles à 2 ans avec une fécondité moyenne pour la majorité des individus. Par rapport aux autres milieux, la croissance de la perche est rapide dans le réservoir du Mirgenbach ; l'espèce atteint des 1 an une taille de 12 cm. Cette croissance est à mettre en parallèle avec les bonnes conditions thermiques du milieu ainsi qu'avec une meilleure disponibilité alimentaire pour les perches avec la diminution de sa population. Les contenus digestifs de la perche sont examinés pour l'étude de son régime alimentaire. Perca fluviatilis se nourrit de crustacés (avec une prédation sélective sur le cladocere daphnia longispina), d'insectes (essentiellement des larves et nymphes de chironomes), de mollusques gastéropodes et des poissons comme le gardon, la gremille (gymnocephalus cernua) et la perche attestant de cas de cannibalisme au sein du réservoir. Cependant, la composition de l'alimentation varie en fonction du sexe et de la taille des perches et également en fonction des saisons. Une synthèse bibliographique de l'espèce et une discussion générale à l'issue de ce travail sur le réservoir du Mirgenbach permettent de comparer nos résultats avec ceux d'autres milieuxThe Mirgenbach reservoir created by pumping water from the river Moselle in 1985 is a safety reservoiir and a buffer zone for the Cattenom nuclear power plant (Moselle, north-east France). With its maximum depth of 20 meters, this reservoir is characterized by its heated waters and the absence of a thermo-stratification. It is an ecological study of this lake-reservoir which contributes to the knowledge of the fish population and the demography of an initially dominant species : the perch, perca fluviatilis. From 1987 to 1991, various fishing techniques were employed on the Mirgenbach lake-reservoir. Two kinds of gill nets were used : traditional nets and vertical nets which took samples from the water surface to the bottom. A set of vertical nets were immersed in stations during fishing sessions spread along the year. Among the various fishing gears used, vertical gill nets turned out to the best sampling device for the analysis of the perch demography. The analysis of catches thanks to these various fishing gears enabled us to know its location and its evolution in the lake-reservoir. All in all, 18 fish species were identified with a majority of perch (perc fluviatilis), roach (rutilus rutilus) and common bream (abramis brama). The multiple correspondence analysis led us to distinguish several groups of stations, each having its own species. The sampled fish with traditional and vertical gill nets as well as angling enabled us to know the selectivity of each device and to study the demographic structure evolution. The number of catches has decreased dramatically within this period. The seasonal repartition of the species in the reservoir was studied is an annual cycle with vertical gill nets. The best catches of this carnivorous fish were made in summer, except in a littoral station close to a spawning area before reproduction time. The vertical distribution of this species according to bathymetry. The perches were found mostly at the bottom of the stations closest to the shore and from the bottom to the surface in the pelagic stations. The reproductive study of the perch is based upon weight index and the maturity stage index. Age is identified by the application of scalimetrie and operculometrie methods. The two corresponding structures can be used equally to describe the perch growth. In the Mirgenbach reservoir, the reproduction of the perch takes place from mid-march to mid-april. Perch may spawn since the end of february. Spawning period takes place precociously one month earlier than in other ponds of the region Lorraine. Males are mature at one year old and females at two years, with an intermediate fecundity for almost fish. In comparison with others lakes, the perch growth is faster in the Mirgenbach reservoir : it reaches 12 cm at one year. This growth speed depends upon the very good thermal conditions and a better availability of food resources with the decreasing of its population. Digestive contents are analysed to study the diet of perch. Perca fluviatilis fed on Crustacean with a selective predation on the cladocera Daphnia longispina, insects mostly chironomes larvae and nymphes, molluscs gasteropodes and fish such as roach (rutilus rutilus), ruffe (gymnocephalus cernua). Cannibalism occurs within perch in the reservoir. Nevertheless, diet depends upon sex and perch length and also seasons. A bibliographic review and a discussion on this Mirgenbach reservoir enables us to compare our results to others
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Schleuter, Diana. "Competition for food between perch (Perca fluviatilis L.) and invasive ruffe (Gymnocephalus cernuus (L.)) in re-oligotrophic Lake Constance." [S.l. : s.n.], 2006. http://nbn-resolving.de/urn:nbn:de:bsz:352-opus-42991.
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FLESCH, ANNE MORETEAU J. C. "BIOLOGIE DE LA PERCHE (PERCA FLUVIATILIS L.) DANS LE RESERVOIR DU MIRGENBACH (CATTENOM, MOSELLE) /." [S.l.] : [s.n.], 1994. ftp://ftp.scd.univ-metz.fr/pub/Theses/1994/Flesch.Anne.SMZ9454.pdf.
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Abdulfatah, Abdulbaset. "Etude du déterminisme environnemental du cycle de reproduction chez la perche commune (Perca fluviatilis)." Thesis, Vandoeuvre-les-Nancy, INPL, 2010. http://www.theses.fr/2010INPL054N/document.
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Cette thèse a déterminé les rôles respectifs de la photopériode et de la température lors des différentes et successives étapes du cycle de reproduction (induction du cycle, vernalisation, ponte) chez la perche commune Perca fluviatilis femelle. La photopériode est le facteur environnemental principal qui synchronise l’induction du cycle de reproduction chez la perche commune, la température joue uniquement un rôle modulateur. Une baisse importante de la durée de la photophase de 4-8 heures est recommandée. Le maintien d'une photopériode constante basée sur une photophase longue et constante (17L : 7D) inhibe l’induction, alors que le maintien d’une température élevée et constante (22-23°C) ne le permet pas. Pour la phase de vernalisation, une photopériode de type jour court (8L : 16D) est nécessaire. Concernant les effets de la température, une forte et progressive baisse de la température (de 22 à 6°C sur 16 semaines) est recommandée pour assurer un développement gonadique complet (ovocytes aux stades de vitellogenèse avancée en fin de phase d’induction et de la maturation finale avant la période de ponte). Des baisses de température plus modérées (de 22 à 14-18°C) altèrent la reproduction, notamment pendant la phase de vernalisation. L’augmentation finale de la température après la vernalisation est le facteur principal de synchronisation de la ponte. Cette étude a permis la mise au point d’un protocole photo-thermopériodique fiable garantissant des taux d’induction et de ponte très élevés, proches de 100%, chez les femellesThis PhD thesis has determined the respective roles of photoperiod and temperature at the different and successive steps of the reproductive cycle (induction of the cycle, wintering period, spawning) in female Eurasian perch Perca fluviatilis. Photoperiod is the main environmental factor which synchronizes the onset of the reproduction cycle in Eurasian perch female, temperature plays only a modulating role. A high photoperiod decrease of 4 or 8 hours is recommended. The maintenance of constant photoperiod based on a long photophase (17L: 7D) delays the onset of the reproductive cycle, whereas the maintenance of a warm and constant temperature (22-23°C) does not delay it. For the wintering period, a photoperiod with a short daylight period (8L : 16D) is required. Concerning the effect of temperature variations, a high and progressive temperature decrease (from 22 to 6°C over 16 weeks) is recommended to ensure a complete ovarian development (all oocytes achieved the advanced vitellogenesis stage at the end of the induction phase and and final maturation stage just before spawning). Slight temperature decreases (from 22 to 14-18°C) alter the reproduction, especially during the chilling period (wintering period). The final increase of temperature (up to 14°C) after the wintering period is the main factor for spawning synchronization. This study allowed the development of a reliable photo-thermal protocol for out-of-season spawning with very high rates (close to 100%) of female response and spawning
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Castets, Marie-Dorothée. "Fonction de reproduction et régulation de la qualité chez la perche commune, Perca fluviatilis." Thesis, Vandoeuvre-les-Nancy, INPL, 2011. http://www.theses.fr/2011INPL082N/document.
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L’amélioration des performances de reproduction des poissons d’élevage nécessite de déterminer les facteurs intrinsèques et extrinsèques influençant la qualité des gamètes d’une part, et de définir des paramètres fiables permettant de prédire les performances de reproduction d’autre part. Notre objectif est donc de comprendre le déterminisme multifactoriel de la reproduction chez la perche commune, Perca fluviatilis. Quatre facteurs nutritionnels (type d’aliment et taux de rationnement distribués lors des phases d’induction et de vernalisation) et 3 facteurs populationnels (poids initial, origine géographique, niveau de domestication) ont été testés. Une différence de réponse entre les sexes a été observée. Le type d’aliment distribué en vernalisation et le poids initial ont modifié l’état général des femelles. Les mâles ont plutôt été sensibles aux taux de rationnement et à l’origine géographique. L’étude des performances de reproduction a montré que le taux de ponte était sous l’influence de l’interaction entre le type d’aliment distribué en induction et en vernalisation, tandis que l’origine géographique a modulé la date de ponte. La régulation des performances de reproduction est donc un mécanisme complexe sous l’influence simultanée de plusieurs facteurs. La seconde partie de ce travail concerne la recherche de marqueurs prédictifs de la qualité des ovules. Nous avons d’abord montré que peu de paramètres morpho-anatomiques des pontes ou ovules sont des prédicateurs fiables. Cependant, l’analyse protéomique a permis de mettre en évidence plusieurs protéines exprimées différemment selon la qualité des pontes, pouvant jouer le rôle de biomarqueurs de qualité des ovulesImproving fish reproduction in breeding conditions implies to understand intrinsic and extrinsic factors influencing gametes quality on the one hand and to define relevant parameters allowing the prediction of fish reproductive performance on the other hand. Our goal was thus to understand the multifactorial determinism of the common perch (Perca fluviatilis) reproduction. Four nutritional factors (type of food and rate of rationing used either during the induction or vernalization phases) and 3 populational factors (initial weight, geographic origin and domestication level of breeders) have been tested. Data show different responses between females and males. type of food during wintering phase and initial broodstock weigh modified female condition. Males have been sensitive to rationing during wintering phase as well as geographical origin. Data show also that spawning rate was under the influence of interaction between kind of food during wintering phase and induction whereas geographical origin modulated the spawning date. The regulation of the performance reproduction is also a complex mechanism influenced by several factors. The second part of this work consisted on the research of parameters potentially predictive of ova quality. Firstly, our work shows that morphometric parameters measured before the fertilization are poorly relevant to predict reproductive performance. However, the proteomic analysis of several spawn allowed us to highlight proteins differently expressed according to the spawn quality, such proteins could be ova quality biomarkers
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Rakauskas, Vytautas. "Introdukuojųjų Ponto–Kaspijos šoniplaukų ir mizidžių poveikis ešerių (Perca fluviatilis) mitybai bei auginimui Lietuvos ežeruose." Master's thesis, Lithuanian Academic Libraries Network (LABT), 2010. http://vddb.laba.lt/obj/LT-eLABa-0001:E.02~2007~D_20101125_183209-76830.
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Lietuvos ežeruose siekiant praturtinti žuvų maistinius išteklius buvo introdukuota keletas Ponto-Kaspijos komplekso šoniplaukų bei mizidžių rūšių. Manyta, kad verslinės žuvys, tame tarpe ir ešeriai specializuosis maitintis šiais vertingais maisto objektais. Atlikti tyrimai parodė, kad ešeriai introdukuotomis rūšimis pradeda maitintis jau pirmaisiais gyvenimo metais. Ešeriams augant, minėtų vėžiagyvių reikšmė jų mityboje didėja. Ežeruose, kur introdukuotosios rūšys litoralėje suformavo gausias populiacijas, šių vėžiagyvių ešerių skrandžiuose pasitaiko daugiau lyginant su ežerais su negausiomis vietinių vėžiagyvių populiacijomis. Atliktos analizės parodė, kad vis tik invaziniai vėžiagyviai kryptingai nekaičia ešerių mitybinės nišos pločio, o ešeriai introdukuotais Ponto-Kaspijos komplekso vėžiagyviais selektyviai nesimaitina. Ešeriai yra „generalistai“ ir maitinasi tuo metu aplinkoje esančiais, lengvai prieinamais bei tinkamais pagal dydį maisto objektais.SUMMARY The influence of the introduced Ponto-Caspian scuds and opossum shrimps on perch (Perca fluviatilis) diet and growth rate in the lakes of Lithuania The purpose of this study was to examine perch (Perca fluviatilis) feeding habits and diet differences between two types of lakes that differ in having and lacking abundant littoral populations of introduced Ponto-Caspian opossum shrimps and scuds. The growth of the perch has been performed in order to answer whether introduced crustaceans really improve fish food basis in lakes. 1104 individuals were used to perform their growth rate analysis. 861 individuals were used to clear their diet. Fish and littoral benthic animal’s samples were collected in 2004 – 2006 summer and fall seasons in 10 Lithuanian lakes (Dusia, Daugai, Asveja, Žeimenys, Šakarvų, Baluošai, Nedingis, Lavysas, Plateliai and Beržoras). Analyses show that perches consume introduced Ponto-Caspian crustaceans from their first year. Kruskal-Walis ANOVA test show significant general lake effect on consuming rate of both scuds and opossum shrimps when comparing between three types of lakes that differ in littoral scuds and opossum shrimps population size. There was bigger consuming rate in lakes with larger crustacean’s populations in four different age groups of perch. We found significant correlations between relative biomass of littoral scuds in the benthic communities and in the perch stomach in three different age groups of perch. However we failed to find... [to full text]
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Ragauskas, Adomas. "Investigation into population genetic structure of eel Anguilla anguilla (L.) and perch Perca fluviatilis L. within the context of anthropogenic activity." Doctoral thesis, Lithuanian Academic Libraries Network (LABT), 2013. http://vddb.laba.lt/obj/LT-eLABa-0001:E.02~2013~D_20130625_092059-72226.
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Seeking for a sustainable exploitation of the populations of commercialy valuable fish species without causing danger to their genetic resources it is necessary to amass extensive data about the population genetic structure of this fish species. When preparing the thesis a total of 221 eels and 262 perch were analysed. Fish samples collected in Lithuania and Latvia were studied using microsatellite DNA, the mtDNA D-loop region and mtDNA cyt b markers. Original primer pairs Ang1 and Ang2 have been designed for the mtDNA analysis of the eel. On the basis of the Anguilla genus species mtDNA D-loop region data obtained during work it can be stated that inland and territorial water bodies of Lithuania contain no A. japonica and A. rostrata species. The molecular investigations carried out indicate that the population genetic structure of the European eel is characterized by the genetic mosaic, which is formed due to the existence of reproductively isolated groups. Statistically significant genetic differentiation between the eel groups naturally recruited to Lithuania and Latvia and introduced to Lithuanian lakes has not been determined (p > 0.05). However, the eels stocked into different lakes of Lithuania differ in their genetic diversity. Pairwise comparisons of the Lithuanian and Latvian perch populations based on the mtDNA D-loop region data revealed that the perch population of Lake Drūkšiai was statistically significantly (p < 0.05) different from all other perch... [to full text]Siekiant tvariai eksploatuoti verslinių žuvų populiacijas nesukeliant pavojaus jų genetiniams resursams būtina sukaupti daug duomenų apie šių rūšių populiacinę-genetinę struktūrą. Iš viso tyrimams panaudoti 221 unguriai ir 262 ešeriai. Lietuvoje ir Latvijoje surinkti žuvų audinių pavyzdžiai tirti naudojant mikrosatelitinės DNR, mtDNR D-kilpos regiono ir mtDNR cyt b žymenis. Ungurių mtDNR analizei sukurtos originalios Ang1 ir Ang2 pradmenų poros. Remiantis disertacinio darbo metu atliktais Anguilla genties rūšių mtDNR D-kilpos regiono tyrimais, galima teigti, jog šiuo metu A. japonica ir A. rostrata rūšių, tiek tirtuose Lietuvos vidaus vandens telkiniuose, tiek Lietuvos teritoriniuose vandenyse nėra. Atlikti molekuliniai tyrimai rodo, kad europinio upinio ungurio populiacinė-genetinė struktūra pasižymi genetine mozaika, kurios susiformavimą lemia reproduktyviai izoliuotos grupės. Tarp natūraliai į Lietuvą ir Latviją atplaukusių ir introdukuotų Lietuvos ežeruose ungurių grupių statistiškai patikima genetinė diferenciacija nenustatyta (p > 0,05), tačiau skirtinguose Lietuvos ežeruose gyvenantys unguriai pasižymi skirtinga genetine įvairove. Atliktų Perca fluviatilis mtDNR D-kilpos regiono tyrimų rezultatai rodo, jog Drūkšių ežero ešerių populiacija statistiškai patikimai (p < 0,05) skiriasi nuo visų kitų Lietuvos ir Latvijos ešerių populiacijų. Nustatyta, kad nuo Lietuvos pietvakarinės dalies iki Latvijos centrinės dalies plyti kelių skirtingų ešerių genetinių linijų kontaktinė... [toliau žr. visą tekstą]
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Ragauskas, Adomas. "Ungurio Anguilla anguilla (L.) ir ešerio Perca fluviatilis L. populiacinės-genetinės struktūros tyrimai antropogeninio poveikio kontekste." Doctoral thesis, Lithuanian Academic Libraries Network (LABT), 2013. http://vddb.laba.lt/obj/LT-eLABa-0001:E.02~2013~D_20130625_092047-20932.
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Siekiant tvariai eksploatuoti verslinių žuvų populiacijas nesukeliant pavojaus jų genetiniams resursams būtina sukaupti daug duomenų apie šių rūšių populiacinę-genetinę struktūrą. Iš viso tyrimams panaudoti 221 unguriai ir 262 ešeriai. Lietuvoje ir Latvijoje surinkti žuvų audinių pavyzdžiai tirti naudojant mikrosatelitinės DNR, mtDNR D-kilpos regiono ir mtDNR cyt b žymenis. Ungurių mtDNR analizei sukurtos originalios Ang1 ir Ang2 pradmenų poros. Remiantis disertacinio darbo metu atliktais Anguilla genties rūšių mtDNR D-kilpos regiono tyrimais, galima teigti, jog šiuo metu A. japonica ir A. rostrata rūšių, tiek tirtuose Lietuvos vidaus vandens telkiniuose, tiek Lietuvos teritoriniuose vandenyse nėra. Atlikti molekuliniai tyrimai rodo, kad europinio upinio ungurio populiacinė-genetinė struktūra pasižymi genetine mozaika, kurios susiformavimą lemia reproduktyviai izoliuotos grupės. Tarp natūraliai į Lietuvą ir Latviją atplaukusių ir introdukuotų Lietuvos ežeruose ungurių grupių statistiškai patikima genetinė diferenciacija nenustatyta (p > 0,05), tačiau skirtinguose Lietuvos ežeruose gyvenantys unguriai pasižymi skirtinga genetine įvairove. Atliktų Perca fluviatilis mtDNR D-kilpos regiono tyrimų rezultatai rodo, jog Drūkšių ežero ešerių populiacija statistiškai patikimai (p < 0,05) skiriasi nuo visų kitų Lietuvos ir Latvijos ešerių populiacijų. Nustatyta, kad nuo Lietuvos pietvakarinės dalies iki Latvijos centrinės dalies plyti kelių skirtingų ešerių genetinių linijų kontaktinė... [toliau žr. visą tekstą]Seeking for a sustainable exploitation of the populations of commercialy valuable fish species without causing danger to their genetic resources it is necessary to amass extensive data about the population genetic structure of this fish species. When preparing the thesis a total of 221 eels and 262 perch were analysed. Fish samples collected in Lithuania and Latvia were studied using microsatellite DNA, the mtDNA D-loop region and mtDNA cyt b markers. Original primer pairs Ang1 and Ang2 have been designed for the mtDNA analysis of the eel. On the basis of the Anguilla genus species mtDNA D-loop region data obtained during work it can be stated that inland and territorial water bodies of Lithuania contain no A. japonica and A. rostrata species. The molecular investigations carried out indicate that the population genetic structure of the European eel is characterized by the genetic mosaic, which is formed due to the existence of reproductively isolated groups. Statistically significant genetic differentiation between the eel groups naturally recruited to Lithuania and Latvia and introduced to Lithuanian lakes has not been determined (p > 0.05). However, the eels stocked into different lakes of Lithuania differ in their genetic diversity. Pairwise comparisons of the Lithuanian and Latvian perch populations based on the mtDNA D-loop region data revealed that the perch population of Lake Drūkšiai was statistically significantly (p < 0.05) different from all other perch... [to full text]
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Peter, Magali Brun-Bellut Jean Gardeur Jean Noël. "Profil et métabolisme des acides gras dans les tissus de la perche comme Perca fluviatilis L." S. l. : INPL, 2008. http://www.scd.inpl-nancy.fr/theses/2008_PETER_M.pdf.
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Wang, Neil. "Déterminisme de la qualité du cycle de reproduction chez la perche commune, Perca fluviatilis : approche multifactorielle." Nancy 1, 2006. http://www.theses.fr/2006NAN10120.
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De nombreux facteurs environnementaux, nutritionnels et populationnels sont susceptibles d’agir sur la qualité de la reproduction chez les poissons. Cette thèse avait pour objectif d’identifier et de hiérarchiser l’importance des effets de ces facteurs et de leurs interactions sur le déterminisme de la qualité de la reproduction chez la perche commune, Perca fluviatilis. Une première expérience multifactorielle a visé à déterminer les facteurs influant sur l’induction du cycle de reproduction. 8 facteurs à 2 modalités ont été testés (amplitude de diminution de la température, timing, cinétique et amplitude de diminution de la photopériode, manipulations, état nutritionnel initial, rationnement et spectre lumineux). Il a été confirmé que les diminutions de température et de photopériode sont les facteurs signaux inducteurs du cycle et suggéré que la température et le timing photopériode constituent des facteurs ultimes. Le stress lié aux manipulations semble être un facteur majeur modulant la vitesse d’entrée en vitellogenèse. Une deuxième expérience multifactorielle à 8 facteurs à 2 modalités (température, état nutritionnel, manipulations, aube, luminosité, type d’aliment, rationnement et photopériode) a porté sur la qualité de la reproduction (sperme, œufs et mortalité des géniteurs). Aucune ponte n’a été obtenue, ce qui suggère que le programme photothermique de contrôle du cycle pourrait être inadéquat. La qualité du sperme semble être déterminée de façon majeure par l’état nutritionnel initial et l’intensité lumineuse. Le déterminisme des fortes mortalités observées s’avère complexe. Un premier modèle qualitatif et déterministe de la qualité du cycle est proposéNumerous environmental, nutritionnal and populationnal factors are likely to be involved in the quality of reproduction in fish. The objective of this PhD study was to determine and ranking the importance of the effects of these factors and their interactions on the determinism of the quality of reproduction in Eurasian perch, Perca fluviatilis. A first factorial experiment aimed at identifying the factors acting of the induction of the reproductive cycle. 8 two-levels factors were tested (amplitude of temperature decrease, timing, kinetics and amplitude of photoperiod decrease, handling, initial nutritional state, feeding and light spectrum). It was confirmed that temperature and photoperiod decreases are the two main cues inducing the reproductive cycle. Handling stress appears to be the most important factor modulating vitellogenesis. A second factorial experiment testing 8 two-levels factors (temperature, nutritional state, handling, dawn, light intensity, food type, feeding and photoperiod) dealt with the quality of reproduction (sperm, eggs and broodstock mortality). No spawning was obtained. This suggests that the photothermal program of control of the reproductive cycle could be inadequate. Sperm quality appears to be mainly affected by nutritional state and light intensity. High mortalities were observed and their determinism could be complex. A first qualitative model of the determinism of the quality of reproduction is proposed
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Hansson, Tomas. "Biomarkers in perch (Perca fluviatilis) used in environmental monitoring of the Stockholm recipient and background areas in the Baltic Sea." Doctoral thesis, Stockholms universitet, Institutionen för tillämpad miljövetenskap (ITM), 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-8143.
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This thesis reports the results of biomarker measurements in three environmental monitoring projects. In the first project, which was part of the Swedish national environmental monitoring, biomarkers were measured annually in female perch (Perca fluviatilis) in two background areas in the Baltic Sea during 1988–2000, resulting in a unique 13-year series of measurements. The most important results were a strong decreasing temporal trend in the gonadosomatic index (GSI) and a strong increasing temporal trend in the hepatic ethoxyresorufin O-deethylase (EROD) activity in the Baltic Proper. In the second project, biomarkers and concentrations of classic pollutants were measured in female perch in the Stockholm recipient 1999–2001. This was the first time a large city was investigated as a point source of pollution, and the gradient was longer and included more stations than customary. Severe pollution conditions in central Stockholm were indicated by the poor health status of the perch: retarded growth, decreased frequency of sexually mature females, low GSI, disturbed visceral fat metabolism, increased hepatic EROD activity, decreased muscle acetylcholinesterase activity, increased frequency of hepatic DNA adducts, and a high concentration of biliary 1-pyrenol. Muscle ΣDDT and ΣPCB were measured as pollution indicators and were 10–28 respectively 12–35 times higher than the background levels in perch from the Baltic Proper. In the Stockholm archipelago two superimposed gradients were found. Whereas the response of several biomarkers consistently decreased with increasing distance from central Stockholm, the response of others first decreased from Stockholm to the middle archipelago and then increased to the open Baltic Sea. The latter biomarkers included the frequency of sexually mature females, GSI, hepatic EROD activity, and hepatic DNA adducts. In the third project, potential toxicity from munitions on the seafloor, at a dumpsite in the Stockholm archipelago, was analysed by the nanoinjection of sediment extracts into newly fertilised rainbow trout (Oncorhynchus mykiss) eggs, followed by the measurement of biomarkers in the developing larvae. No biological effects of the dumped munitions were found. The same stations in the Stockholm archipelago as in the second project were investigated as a positive control. The results of the three projects agreed well, which demonstrated the continuous pollution of the Baltic Sea and the severe pollution conditions and adverse biological effects in central Stockholm. Further investigations are urgently needed to identify which pollutants or other factors are causing the observed biological effects, both in the background areas in the Baltic Sea and in the Stockholm recipient.
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Almeida, Tainá Rocha de. "Study of gene expression patterns in Eurasian perch (Perca fluviatilis Linnaeus, 1758) eggs related to their quality and to the domestication process." Electronic Thesis or Diss., Université de Lorraine, 2019. http://www.theses.fr/2019LORR0288.
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Avec le déclin grandissant des prises de pêches, une augmentation de la production piscicole est attendue pour les prochaines années. Cependant, de nombreux problèmes de reproduction sont observés dans les élevages, principalement une mortalité élevée au début de la vie. Cela concerne principalement des espèces piscicoles pour lesquelles le processus de domestication commence. Mon travail de thèse a visé à mieux comprendre et potentiellement aider à améliorer les performances de reproduction en étudiant le contenu transcriptomique des œufs de perche commune (Perca fluviatilis) en lien avec leur qualité. Ces résultats participent à la compréhension des mécanismes moléculaires impliqués dans la mortalité embryonnaire précoce. Cette espèce, en cours de domestication, revêt une grande importance dans le contexte de la diversification des espèces d’intérêt aquacole en Europe continentale. J’ai utilisé des analyses par puce à ADN et RT-qPCR pour caractériser les profils d'expression génique dans les œufs de perche de qualité variables. Les expériences ont été menées dans deux contextes scientifiques. Dans un premier temps, j’ai comparé l’effet des méthodes d’évaluation de la qualité des œufs sur les résultats transcriptomiques obtenus. Ainsi, les œufs ont été classés dans des groupes de qualité (bonne ou mauvaise) en utilisant divers critères liés au développement embryonnaire (taux de survie, taux de malformation) et divers seuils limites pour borner ces groupes. L’utilisation de critères de survie embryonnaire précoces a permis d'identifier des profils d'expression génique distincts entre les groupes de qualité. Cependant, le nombre et la nature des gènes exprimés de manière différentielle (DEG) étaient variables. Un seul gène était exprimé de manière différentielle dans toutes les analyses, quelles que soient les conditions. Cela montre à quel point les résultats transcriptomiques sont sensibles aux méthodes d’évaluation qui doivent être sérieusement pris en compte en amont de comparaisons intra et inter-espèces. Dans un deuxième temps, j’ai comparé le contenu transcriptomique d’œufs de femelles avec des histoires de domestication différentes. Dans cette étude, les femelles les plus proches des populations sauvages présentaient une meilleure qualité d'œufs. En outre, deux modèles distincts d'expression génique ont été observés et plus de 300 DEG ont été identifiés entre les populations. Étant donné que les causes de la variabilité élevée des performances de reproduction des espèces en cours de domestication sont mal connues, cette découverte pourrait ouvrir de nouvelles hypothèses d’investigation. Enfin, il devenait important de déterminer le moment où le gène identifié dans les approches précédentes soutiendrait exclusivement le développement embryonnaire précoce. Dans ce but, une étude préliminaire a permis de faire une première évaluation de l’activation du génome zygotique (ZGA) chez cette espèce. L’ensemble de ces résultats ouvre la voie vers l’établissement de nouvelles méthodes d’investigation de la qualité des gamètes chez la perche commune. Ces méthodes permettront de faire des études précises de l’évolution du succès de développement à chaque génération au cours d’un processus de domestication. Des méthodes similaires pourraient être établies chez d’autres espèces en prenant en compte leurs particularités. Il serait alors intéressant de tenter d’étudier des espèces présentant des caractères communs ou divergents. Nous pourrons alors tenter de comprendre les régulations propres à chaque espèce ou au contraire largement retrouvés chez plusieurs espèces de poissonIn the aquaculture context, increase on production are expected for the next years and yet, many reproductive issues are reported, including high mortality during early life stages. It concerns mostly species for which the domestication process is at the very beginning. My PhD work aimed at better understanding and potentially helping improving reproductive performance by investigating eggs the transcriptomic content of the Eurasian perch (Perca fluviatilis) eggs in association with their quality which may constitute one of the sources for embryonic mortality. Eurasian perch is a species, in process of domestication, with strong importance for aquaculture diversification in inland Europe. We employed microarray and RT-qPCR analyses to characterize gene expression patterns of Eurasian perch eggs presenting different potential to develop properly after fertilization. The experiments were conducted in two scientific contexts. In the first one, different methods to access egg quality were employed and their potential impacts on the transcriptomic results were evaluated. Therefore, when eggs were classified into the respective quality groups (high or low) using early embryonic survival as criteria, we were always able to identify distinct patterns of gene expression between quality groups. However, the number and nature of the differentially expressed genes (DEG) were variable and only one gene was commonly differentially expressed no matter the methods employed. This shows how transcriptomic results are sensitive to methods and should be deeply considered for intra- and inter-species comparisons. The second context consisted of investigating whether females presenting different histories of domestication would differ in their eggs mRNA content, and how it affects egg quality. In this study, females closest to wild populations presented better egg quality. In addition, two distinct patterns of gene expression were observed and more than 300 DEG were identified between populations. Because not much is known about the causes of high variability in reproductive performance in species in process of domestication, this finds could open new hypothesis of investigation. Finally, it became important to determine the moment until which the gene identified in the previous approaches were exclusively supporting embryonic early development. With this purpose, a preliminary study allowed making a first evaluation of the zygotic genome activation (ZGA) in this species. As a whole, this study identified numerous maternal-effect genes which implication in embryos early development should be further investigated. In addition, these results suggest that more comparable methods to investigate egg quality in Eurasian perch could be established. These methods will make possible more precise studies in the variation of the development success under the influence of distinc factors, such the domestication process. Similar methods could also be established in other species considering their own common or divergent characters. It would help understanding molecular mechanisms species specific or widely found in finfish species
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Felicia, Skorsdal. "Har det skett en förändring i abborrens (Perca fluviatilis) tillväxt i sjön Tåkern mellan år 1978 jämfört med år 2019?" Thesis, Linköpings universitet, Institutionen för fysik, kemi och biologi, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-166765.
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The growth in perch (Perca fluviatilis) is generally slow but varies depending on living conditions. For instance, growth is more rapid in warmer water temperature and when there is reduced intra- and interspecific competition for food. The cormorant (Phalacrocorax carbo) was established in Lake Tåkern in 1994 and could possibly have an effect on the growth of perch due to predation of small perch and competition for food with larger perch. The aim of this study was to examine whether the growth of perch had changed from year 1978, when a previous study on perch was preformed, to a recent fish survey in 2019 in lake Tåkern. The aim of the study was to assess if any changes in growth could be explained by predation and competition from cormorants. The aim of the study was also to examine whether there was a difference in growth between females and males. The age was determined by using the opercular bone and an age analysis was done to compare the growth between year 1978 and 2019. The results showed that the growth of 1-3-year-old perch was higher in year 1978 than in 2019. This was contrary to the expected outcome, that the predation from cormorants should had decreased competition for young perch in 2019. Previous studies on perch have shown a difference between males and females with an age over 2 years old. However, by the results there is no support that differences between males and females have affected the difference in growth at ages 1-3 years old between 1978 and 2019. As there was no difference between the sexes, any difference in growth between 1978 and 2019 could not be explained by an altered sex ratio. Since there were only a few older individuals 2019 comparison of growth for individuals over 4 years old were not possible to do. The conclusion is that there was no support that cormorants reduced the competition for smaller perch. Cormorants could possibly have contributed to low number of older individuals in 2019.
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Probst, Wolfgang Nikolaus. "New insights into the ecology of perch Perca fluviatilis L. and burbot Lota lota (L.) with special focus on their pelagic life-history." [S.l. : s.n.], 2008. http://nbn-resolving.de/urn:nbn:de:bsz:352-opus-72670.
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Ylva, Karlberg. "The influence of northern pike on the diet of Eurasian perch." Thesis, Umeå universitet, Institutionen för ekologi, miljö och geovetenskap, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-137832.
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Top predators in aquatic ecosystems often have strong top-down effects on the ecosystem. Northern pike (Esox lucius) has been documented to cause whitefish (Coregonus lavaretus) populations to diverge into different ecomorphs. This can facilitate piscivory in other predators as a novel resource becomes available to them in the form of dwarf whitefish. The aim of this study is to examine whether the presence of pike causes Eurasian perch (Perca fluviatilis) to shift their diet from insectivory to piscivory, and whether this is directly driven by whitefish polymorphism. Stomach contents of 147 perch from lakes with and without pikes were analyzed. The results show that the presence of pike has a clear influence on the diet of the perch. In lakes without pike, perch are mostly insectivorous, and in lakes with pike, they are mostly piscivorous. This diet shift appears to be driven by whitefish availability, as a majority of the diet of perch in pike lakes consisted of whitefish, while none of the fish eaten by perch in non-pike lakes was whitefish. In addition, the results showed that perch undergo the diet shift from insectivory to piscivory at a smaller size when coexisting with pike. This study can be added to the growing body of evidence for the ecological significance of pike.
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Sulistyo, Isdy. "Contribution à l'étude et à la maîtrise du cycle de reproduction de la perche eurasienne Perca fluviatilis L." Nancy 1, 1998. http://www.theses.fr/1998NAN10315.
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Cette thèse porte sur la reproduction de la perche eurasienne Perca Fluviatilis. Dans un premier temps, un cycle annuel de reproduction (avril 1995 - avril 1996 ; étang de Lindre, Moselle) est décrit en présentant les principales variations morpho-anatomiques, histologiques et endocrinologiques qui accompagnent les processus de la reproduction chez des geniteurs males et femelles (100-200 g). Leur impact sur la composition chimique des tissus est également étudié. Dans un second temps, des travaux réalisés en laboratoire précisent les effets de facteurs environnementaux (température de l'eau et photopériode) sur la gonadogenèse. Chez les femelles, durant la phase de repos sexuel (mai-août 1995), le diamètre ovocytaire (do <200m), les indices gonadosomatiques (IGS <1%) et hépatosomatiques (IHS), et les teneurs plasmatiques en 17β-oestradiol (E2), phosphore protéique (PPP), testostérone (T) et 17α,20β-dihydroxy-1-pregnen-3-one (17,20β-P) restent faibles, alors que l'indice viscérosomatique (IVS 4-6%) est maximal. L'ovogenèse débute fin août - début septembre lorsque la température de l'eau diminue de 26 a 14,1°C. Dès lors, l'IGS augmente progressivement jusqu'à la mi-mars (15%), puis fortement jusqu'à la ponte (25% , do = 850 m) qui intervient en avril (14-15°C). Les taux d' E2 et de PPP augmentent significativement en septembre, puis la teneur en E2 s'élève fortement en novembre (2-3 ng. ML-1). à partir de décembre, la concentration en T atteint rapidement 15-27 ng. ML-1. Les taux d' E2 de PPP et de T restent élevés jusqu'à la ponte ce qui indique le maintien d'une vitellogenèse active. Pendant la période peri-ovulatoire, un pic d' E2 (4,96 ng. ML-1) survient, alors que le taux de T diminue et les teneurs en 17,20β-P restent faibles (0,2-0,6 ng. ML-1). Aucun pic de 17,20β-P n'est observé. Chez les males, l'GS (0,2%), l'IHS (1%) et les teneurs en T (<0,5 ng. ML-1) et en 11-kétotestostérone (11KT) sont faibles durant la période de repos sexuel, alors que l'IVS est élevé (3,9%). Un IGS élevé (8,5%) est enregistré en septembre, puis il diminue et demeure proche de 5% jusqu'à la période de ponte. Un pic de concentration en T est noté en janvier (12 ng. ML-1), suivi d'un pic de 11KT en février (5 ng. ML-1). Au cours de la période peri-ovulatoire, la teneur en T s'élève de nouveau, alors que celle de 11KT diminue. Les testicules produisent des spermatozoïdes dès le mois de novembre. La gonadogenèse correspond à un investissement énergétique considérable, notamment pour les femelles. Chez ces dernières, la teneur gonadique en lipides totaux passe progressivement de 14-16% en été à 24-26% des matières sèches (MS) au début du mois de mars. Celle-ci chute à 18-20% durant la période de pré-ponte et de maturation ovocytaire. La gonadogenèse affecte peu la composition chimique du muscle, même si sa teneur en lipides totaux croit de 2-3% à 4-5% MS durant l'automne et l'hiver. En fait, le développement des gonades semble mobiliser principalement les réserves lipidiques périviscérales, notamment durant les périodes de septembre-décembre et de mars-avril. Ces réserves se constituent au cours des périodes de repos sexuel et de janvier-février. L'application de programmes thermo-photopériodiques permet une gonadogenèse normale et l'obtention de pontes décalées en dehors de la période naturelle de ponte. Les variations de la température de l'eau joue un rôle majeur, alors que celles de la photopériode ont une incidence mineure. La durée de la phase de maintien au froid (6°c) doit être supérieure à 3 mois, une durée de 5 mois convient.
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Karlsson, Konrad. "The effect of visibility and predators on foraging efficiency in littoral and pelagic perch." Thesis, Uppsala universitet, Limnologi, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-182653.
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Phenotypic plasticity in Eurasian perch (Perca fluviatilis) can be driven by a trade-off for ecological specialisation to littoral and pelagic resources. Previous studies on perch have found that this specialisation can have different effects on linkage between the littoral and pelagic food web depending on water transparency. In this study I aimed to answer how foraging efficiency and prey preference of phenotypic divergent perch are affected by high and low water transparency, and the presence of a predator in a series of aquarium experiments. Two different phenotypes of perch were kept in littoral and pelagic environments in the lab. By presenting perch with Daphnia sp. and Ephemeroptera, either separately or combined. I found that in clear water the littoral and pelagic phenotypes were comparatively more efficient on resources that were representative of their habitats (Ephemeroptera and Daphnia, respectively) and that both phenotypes prefer Ephemeroptera over Daphnia. In low visibility the differences in foraging efficiency between phenotypes when feeding on Daphnia disappeared but remained similar to clear water when feeding on Ephemeroptera. When vision was constrained littoral and pelagic perch showed no sign of prey preferences. In the presence of a predator the difference in foraging efficiency between the phenotypes, and also prey preference disappeared. I found that littoral phenotypes interacted more with other group members than did pelagic phenotypes, when foraging on littoral prey. And for perch in general, when foraging for Daphnia the interaction among group members was markedly reduced compared to when foraging for Ephemeroptera. In this study I show that morphological adaptation and prey choice is affected by visibility and predation. I also give suggestions how and argue why this can affect linkage of food webs and the community composition in littoral and pelagic habitats.
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Bergek, Sara. "Population divergence at small spatial scales : – theoretical and empirical investigations in perch." Doctoral thesis, Uppsala : Acta Universitatis Upsaliensis, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-107223.
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Molzen, Bettina Ulla. "Die Auswirkung des Befalls mit Plerocercoiden des Hechtbandwurms (Triaenophorus nodulosus (P.)) auf den Flussbarsch (Perca fluviatilis L.) im Bodensee-Obersee." Diss., lmu, 2006. http://nbn-resolving.de/urn:nbn:de:bvb:19-49995.
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Ben, Khadher Sana. "Étude de la variabilité génétique de populations sauvages et captives de la perche eurasienne Perca fluviatilis, espèce en cours de domestication." Thesis, Université de Lorraine, 2015. http://www.theses.fr/2015LORR0197.
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La diversification de la production, par la domestication de nouvelles espèces de poissons, constitue l’une des solutions pour une aquaculture durable. Dans ce contexte, l’élevage de la perche Eurasienne, Perca fluviatilis, s’est bien développé ces dernières années permettant aujourd’hui une production stable et croissante. Le progrès de la filière requiert, la mise en œuvre de programmes de sélection génétique pour améliorer, entre-autres, la croissance, la reproduction, et la résistance aux maladies. Pour ce faire, la caractérisation génétique des stocks de poisson actuellement en élevage est un pré-requis indispensable afin d’évaluer si la variabilité génétique est suffisante. Au cours de ce travail, nous avons analysé la variabilité génétique entre les populations sauvages de deux lacs alpins (lacs Léman et Neuchâtel) dont les populations sont utilisées comme fondatrices par les perciculteurs et les stocks de deux fermes d’élevage. Nous avons trouvé une seule population panmictique dans le lac Léman, alors que deux sous-populations ont été identifiées dans le lac Neuchâtel et dont la variabilité génétique est plus forte. Par contre, ces populations sauvages ne sont pas représentées dans les stocks d’élevage bien qu’elles étaient utilisées pour fonder les stocks de géniteurs. De plus, la variabilité génétique est plus forte dans les populations captives. Entre les géniteurs et leurs descendances, la diversité génétique n’a pas diminué malgré une faible augmentation de la consanguinité. Ainsi, ce travail permettra aux perciculteurs de mettre en place une réelle gestion génétique de leurs cheptels et par la suite de développer des programmes de sélection. De plus, il a permis de mieux comprendre les liens possibles entre le processus de domestication et l’évolution de la variabilité génétiqueThe diversification of production, by the domestication of new fish species, is one of the possible solutions for sustainable aquaculture. In this context, the farming of the Eurasian perch, Perca fluviatilis, has developed well in recent years allowing today a stable and increasing production. The progress of the sector requires, among others, the establishment of breeding programs to improve, growth, reproduction and disease resistance. For this, the genetic characterization of currently farmed fish stocks is an essential prerequisite to assess whether genetic variation is sufficient. In this work, we analyzed the genetic variability among wild populations of two alpine lakes (lakes Geneva and Neuchâtel) whose populations are used by fish farmers to establish their stocks. We found one panmictic population in Lake Geneva, while two sub-populations were identified in Lake Neuchâtel, whose genetic variability is higher. However, those wild populations are not found in captive stocks. In addition, the genetic variability is higher in captive populations. Between parents and their offspring, the genetic diversity has not decreased despite a small increase in inbreeding. Thus, this work will allow fish farmers to set up a real genetic management of their stocks and subsequently to develop breeding programs. Moreover, it provides a better understanding of the possible links between the process of domestication and the evolution of genetic variability
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Bergström, Kristofer. "Rapid Changes in Salinity and Cyanobacterial Exposure Influence condition of Young of the Year (YOY) Perch (Perca fluviatilis) : A Field Study in the Curonian Lagoon(Lithuania)." Thesis, Linnéuniversitetet, Institutionen för naturvetenskap, NV, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-7582.
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Two decades ago the recruitment of YOY perch (Perca fluviatilis) started to decline along the Swedish east cost of the Baltic Sea. Factors that influence recruitment are e.g. eutrophication that causes habitat losses and overfishing of cod (Gadus morhua) which causes cascading effects in the food web. Filamentous cyanobacterial blooms are often toxic and has increased in the Baltic Sea and its coastal waters. The aim of this field study was to evaluate the effects of salinity and cyanobacterial exposure on fitness related parameters of young of the year (YOY) perch (Perca Fluviatilis) in a natural environment. Our study was performed in the Curonian Lagoon (Lithuania) in August 2009. The lagoon offers a temporary salinity gradient (wind induced influxes from the Baltic Sea) ranging from 7 psu in the north to 0 psu in the south. Submerged enclosures containing YOY perch were set up at three different locations along the salinity gradient in the Lagoon (referred to as North, Middle, South). The duration of the experiment was 21 or 27 days, depending on treatment. Measurements of perch condition were specific growth rate, somatic condition index (SCI) and whole fish lipid and protein content. Average chl a values for the three stations during the experimental time were: north 180 ± 70 µg/l chl a, middle 133 ± 36 µg/l chl a and south 180 ± 52 µg/l chl a. The North and the Middle stations experienced two different salinity influxes reaching a maximum salinity of 6.5 psu at the northern station. The duration of each saline influx was approximately 4-6 days. The saline water did not reach the Southern station at any time. Results show that perch from the southern station were in best condition in terms of specific growth rate and contents of total lipids. Compared to the South the perch condition declined to the Middle station and was lowest at the Northern station which experienced the highest degree of fluctuation in terms of salinity and cyanobacterial exposure. Examination of the abundance of the main food resource at the different stations revealed no statistical differences, which suggest that availability of food was not a factor in explaining the differences in growth. The results possibly indicate that a changing environment with the potential synergistic negative effects of salinity and cyanobacteria has a higher negative impact on YOY perch condition compared to constantly high concentrations of cyanobacteria.
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Mairesse, Guillaume Brun-Bellut Jean. "Déterminisme ante mortem et variabilité de la qualité nutritionnelle, technologique et organoleptique (couleur et morphologie) de la perche commune perca fluviatilis (L.)." Vandoeuvre-les-Nancy : INPL, 2005. http://www.scd.inpl-nancy.fr/theses/2005_MAIRESSE_G.pdf.
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Mairesse, Guillaume. "Déterminisme ante mortem et variabilité de la qualité nutritionnelle, technologique et organoleptique (couleur et morphologie) de la perche commune perca fluviatilis (L. )." Vandoeuvre-les-Nancy, INPL, 2005. http://docnum.univ-lorraine.fr/public/INPL/2005_MAIRESSE_G.pdf.
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L'objet de ce travail est d'étudier la variabilité de la qualité de la perche commune d'élevage et sauvage (Perca fluviatilis) ainsi que le déterminisme de cette qualité. Cette dernière est définie par trois composantes: organoleptique (morphologie et couleur), technologique (rendement de filetage, indices morpho-anatomiques) et nutritionnelle (teneur en lipides, profil en acides gras du filet). La qualité de la perche présente une variabilité selon l'origine géographique, la saison de capture et le mode d'élevage. Pour les poissons sauvages, cette variabilité affecte principalement la composante organoleptique et la composante nutritionnelle. Les perches d'élevage se différencient des poissons sauvages par les composantes technologiques et nutritionnelles: les teneurs en graisse périviscérale augmentent avec le niveau d'intensification de l'élevage, de même que les teneurs en acides gras mono-insaturés et poly-insaturés n-6 (n-6 PUFA) au détriment des n-3 PUFA. Il n'existe donc pas une qualité de la perche mais plutôt des qualités. Dès lors, des hypothèses ont été formulées quant aux facteurs responsables de cette variabilité, puis testées. Deux populations de perches sauvages d'origine géographique différente ont été élevées, dès le stade œuf, au laboratoire, dans des conditions environnementales et trophiques identiques. Les résultats ont montré que seule la composante nutritionnelle présente des différences entre ces deux populations. Ainsi, l'expression phénotypique de la qualité est sous la dépendance du facteur origine (génotype) et de facteurs environnementaux. Parmi ceux-ci, 4 facteurs à 2 modalités ont été testés dans 8 unités expérimentales par plan d'expériences fractionnaires: origine des lipides alimentaires, taux de rationnement, densité et domestication. La domestication et l'origine des lipides alimentaires sont les facteurs essentiels du déterminisme de la qualité chez la perche. Ils agissent soit en facteur simple soit en interactionThe purpose of these experimental studies was to assess the variability of quality in farmed and wild Eurasian perch (Perca fluviatilis) and its determinism. Quality is divided into three components: organoleptical (morphology and color), technological (filleting yield, morpho-anatomical index) and nutritional (total lipids content and fatty acids composition in fillet). The quality of perch shows variability according to the geographic origin, season and rearing systems. Farmed perch differ from wild counterparts by technological and nutritional components: perivisceral fat content and n-6 poly-unsaturated fatty acids (PUFA) increase with the intensification level of farmed system, whereas n-3 PUFA decrease. Thus, there is not only one perch quality but rather many perch qualities. Consequently, hypothesis have been formulated about factors responsible for the variability of quality and then tested. Two populations of wild perch from different geographic origin were reared in laboratory from eggs stage, in the same environmental and trophic conditions. The results show that only nutritional component displays differences between the two populations. Thus, phenotypical expression of the quality is under control of both origin (genotype) and environmental factors. Among these factors, 4 factors with 2 modalities were tested in 8 experimental units using a fractional factorial design: dietary lipids origin, feeding rate, density and domestication. Domestication and dietary lipids origin (simple factor or interaction) were found as the main factors of the determinism of perch quality
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Fridolfsson, Emil. "Kan fiskpredation reglera populationer av storspigg (Gasterosteus aculeatus) i Östersjön?" Thesis, Linnéuniversitetet, Institutionen för naturvetenskap, NV, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-15113.
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Fiskbestånden i Östersjön har sedan början av 1980-talet genomgått en omfattande förändring. Stora predatorer, som torsk (Gadus morhua) och abborre (Perca fluviatilis) har minskat i antal medan det finns tecken på att storspigg (Gasterosteus aculeatus) har ökat. Denna sannolika ökning av storspigg skulle kunna ha att göra med minskningen av både torsk och abborre som predatorer i de kustnära tångbältena. För att undersöka detta utfördes ett mesokosmexperiment där torskens och abborrens förmåga att predera på storspigg undersöktes, både i ljus och mörker. Hypoteserna som arbetet utgick ifrån var att torsk var en bättre predator i mörker än i ljus och att torsk var en bättre predator än abborre i mörker. Resultaten visar på att torsk är den bättre predatorn i både ljus och mörker, samt att den är lika framgångsrik i mörker som i ljus. Detta tyder på att torskens försvinnande skulle kunna vara en bidragande faktor till ökningen av storspigg. Ytterligare visades abborren vara en mer framgångsrik predator i mörker än i ljus, detta trots att den alltid anges som en visuell predator. Detta visar att även minskningen av abborre skulle kunna vara en anledning till att storspiggen ökar.
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Laude, Uwe. "Verteilung und Ernährung larvaler und juveniler Stadien von Plötze (Rutilus rutilus (L.)) und Barsch (Perca fluviatilis L.) im Biomanipulationsexperiment Feldberger Haussee (Mecklenburg-Vorpommern)." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2003. http://nbn-resolving.de/urn:nbn:de:swb:14-1049355254781-84243.
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In der Studie wurde die Ernährung und die Verteilung von larvalen und juvenilen Stadien von Plötze (Rutilus rutilus (L.)) und Barsch (Perca fluviatilis L.) untersucht. Untersuchungsgewässer war der Feldberger Haussee, ein geschichteter eutropher Hardwassersee, der seit über 15 Jahren biomanipuliert wurde. Der Bestand an Barschen war in diesem Gewässer im gesamten Biomanipulationszeitraum sehr gering (< 1% der Gesamtfischbiomasse). Längerfristig stabilisiert, aus wissenschafticher Sicht, eine hoher Bestand an piscivoren Barschen die Effekte der Biomanipulation. Ziel der Untersuchung war daher die Überprüfung der Hypothese, dass das Vorhandensein von Konkurrenz um die Ressource Zooplankton zwischen den juvenilen Barsch und Plötzen für den geringen Barschbestand verantwortlich ist (PERSSON & GREENBERG 1990, PERSSON et al. 1991). Die Ergebnisse der Untersuchungen ließen sich in folgenden Punkten zusammenfassen: i) Der juvenile Barsch segregierte in der Hochsommer- bis Herbstperiode in eine spezielle Nahrungsnische. Die beiden Fischarten unterschieden sich deutlich bezogen auf die Art der bevorzugten Zooplankter (0+-Barsch vorwiegend Eudiaptomus, Diaphanosoma, Leptodora; 1+/2+-Plötzen fraßen Cladocerennahrung Bosmina und in hohen Anteilen auch Daphnia). Separation und Aufteilung der Zooplanktonresourcen konnte auch für die bevorzugte Größe der Zooplankter beobachtet werden. Die hohen Wachstumsraten und der gute Konditionszustand des juvenilen Barsches sowie das Fehlen von Wintermortalität ließen konkurrenzinduzierte Mortalität als Begründung für den geringen Bestand nicht glaubhaft erscheinen. ii) Die räuberbedingte saisonale Mortalität der juvenilen Barsche in der Hochsommer- bis Herbstperiode ließ sich bei den 0+-Barschen und 1+-Barschen jeweils auf bis zu 90% einschätzen. Dadurch wurde auch ein starker Jahrgang (wie 1997) innerhalb der ersten zwei Lebensjahre auf bis zu 99% reduziert. iii) Als Alternativhypothese wurde aus den Ergebnissen der Studie und den Bedingungen am Feldberger Haussee gefolgert, dass eine Kombination von langer zooplanktivorer Phase und einem hohen Bestand an effektiven pelagischen Piscivoren (wie Sander lucioperca L.) für den geringen Barschbestand verantwortlich istIn the study the feeding behaviour and distribution of larval and juvenile stages of roach (Rutilus rutilus (L.)) and perch (Perca fluviatilis L.) was examined. The object of the study was the Lake Haussee, an stratified eutrophic hardwater lake that was biomanipulated for more than fifteen years. Over the whole period of biomanipulation the portion of perch population did not reach the level of one percent of the total fish biomass. From the scientific point of the view, a high biomass of piscivorous perch may stabilize the effects of biomanipulation in the long run. The aim of the study was to evaluate the hypothesis of strong competitive interaction between juvenile roach and perch for zooplankton, which could be responsible for the minor population of perch in lakes (PERSSON & GREENBERG 1990, PERSSON et al. 1991). The results of the study can be summarised as follows: i) In the period of midsummer to autumn juvenile perch segregated to a special food niche. In comparison to 1+/2+-roach, which fed on cladocerans (e.g. Bosmina and a high portion of Daphnia), 0+-perch preferred Eudiaptomus, Diaphanosoma and Leptodora. Thus, partitioning and separation were also observed for size-selectivity. Furthermore, the high growth rates and the good state of condition of the young perch as well as the lack of winter mortality did not indicate a competitive-induced mortality in the Lake Haussee. ii) In the period of midsummer to autumn the predator-induced seasonal mortality of juvenile perch (groups like 0+/1+) was estimated nearly up to 90 percent. Thereby, also a strong age group (like 1997) of juvenile perch was reduced up to 99 percent within the first two years of life. iii) The results of this study supported an alternative hypothesis: the morphological conditions of Lake Haussee, a prolonged zooplanktivore period of juvenile perch in combination with a strong stock of an effective pelagic piscivore predator (like Sander lucioperca L.) are responsible for the low perch stock
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Laude, Uwe. "Verteilung und Ernährung larvaler und juveniler Stadien von Plötze (Rutilus rutilus (L.)) und Barsch (Perca fluviatilis L.) im Biomanipulationsexperiment Feldberger Haussee (Mecklenburg-Vorpommern)." Doctoral thesis, Technische Universität Dresden, 2001. https://tud.qucosa.de/id/qucosa%3A24212.
Full textAbstract:
In der Studie wurde die Ernährung und die Verteilung von larvalen und juvenilen Stadien von Plötze (Rutilus rutilus (L.)) und Barsch (Perca fluviatilis L.) untersucht. Untersuchungsgewässer war der Feldberger Haussee, ein geschichteter eutropher Hardwassersee, der seit über 15 Jahren biomanipuliert wurde. Der Bestand an Barschen war in diesem Gewässer im gesamten Biomanipulationszeitraum sehr gering (< 1% der Gesamtfischbiomasse). Längerfristig stabilisiert, aus wissenschafticher Sicht, eine hoher Bestand an piscivoren Barschen die Effekte der Biomanipulation. Ziel der Untersuchung war daher die Überprüfung der Hypothese, dass das Vorhandensein von Konkurrenz um die Ressource Zooplankton zwischen den juvenilen Barsch und Plötzen für den geringen Barschbestand verantwortlich ist (PERSSON & GREENBERG 1990, PERSSON et al. 1991). Die Ergebnisse der Untersuchungen ließen sich in folgenden Punkten zusammenfassen: i) Der juvenile Barsch segregierte in der Hochsommer- bis Herbstperiode in eine spezielle Nahrungsnische. Die beiden Fischarten unterschieden sich deutlich bezogen auf die Art der bevorzugten Zooplankter (0+-Barsch vorwiegend Eudiaptomus, Diaphanosoma, Leptodora; 1+/2+-Plötzen fraßen Cladocerennahrung Bosmina und in hohen Anteilen auch Daphnia). Separation und Aufteilung der Zooplanktonresourcen konnte auch für die bevorzugte Größe der Zooplankter beobachtet werden. Die hohen Wachstumsraten und der gute Konditionszustand des juvenilen Barsches sowie das Fehlen von Wintermortalität ließen konkurrenzinduzierte Mortalität als Begründung für den geringen Bestand nicht glaubhaft erscheinen. ii) Die räuberbedingte saisonale Mortalität der juvenilen Barsche in der Hochsommer- bis Herbstperiode ließ sich bei den 0+-Barschen und 1+-Barschen jeweils auf bis zu 90% einschätzen. Dadurch wurde auch ein starker Jahrgang (wie 1997) innerhalb der ersten zwei Lebensjahre auf bis zu 99% reduziert. iii) Als Alternativhypothese wurde aus den Ergebnissen der Studie und den Bedingungen am Feldberger Haussee gefolgert, dass eine Kombination von langer zooplanktivorer Phase und einem hohen Bestand an effektiven pelagischen Piscivoren (wie Sander lucioperca L.) für den geringen Barschbestand verantwortlich ist.In the study the feeding behaviour and distribution of larval and juvenile stages of roach (Rutilus rutilus (L.)) and perch (Perca fluviatilis L.) was examined. The object of the study was the Lake Haussee, an stratified eutrophic hardwater lake that was biomanipulated for more than fifteen years. Over the whole period of biomanipulation the portion of perch population did not reach the level of one percent of the total fish biomass. From the scientific point of the view, a high biomass of piscivorous perch may stabilize the effects of biomanipulation in the long run. The aim of the study was to evaluate the hypothesis of strong competitive interaction between juvenile roach and perch for zooplankton, which could be responsible for the minor population of perch in lakes (PERSSON & GREENBERG 1990, PERSSON et al. 1991). The results of the study can be summarised as follows: i) In the period of midsummer to autumn juvenile perch segregated to a special food niche. In comparison to 1+/2+-roach, which fed on cladocerans (e.g. Bosmina and a high portion of Daphnia), 0+-perch preferred Eudiaptomus, Diaphanosoma and Leptodora. Thus, partitioning and separation were also observed for size-selectivity. Furthermore, the high growth rates and the good state of condition of the young perch as well as the lack of winter mortality did not indicate a competitive-induced mortality in the Lake Haussee. ii) In the period of midsummer to autumn the predator-induced seasonal mortality of juvenile perch (groups like 0+/1+) was estimated nearly up to 90 percent. Thereby, also a strong age group (like 1997) of juvenile perch was reduced up to 99 percent within the first two years of life. iii) The results of this study supported an alternative hypothesis: the morphological conditions of Lake Haussee, a prolonged zooplanktivore period of juvenile perch in combination with a strong stock of an effective pelagic piscivore predator (like Sander lucioperca L.) are responsible for the low perch stock.
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Richter, Richard. "Nahrungsaufnahme und Entwicklung von larvalen und juvenilen Flussbarschen (Perca fluviatilis L.) aus dem Königssee unter besonderer Berücksichtigung der Histologie des Darmtraktes und des Pankreas." [S.l. : s.n.], 2002. http://deposit.ddb.de/cgi-bin/dokserv?idn=964720477.
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Tamazouzt, Lakhdar. "L'alimentation artificielle de la perche perca fluviatilis en milieux confinés (eau recyclée, cage flottante) : Incidence sur la survie, la croissance et la composition corporelle." Nancy 1, 1995. http://docnum.univ-lorraine.fr/public/SCD_T_1995_0399_TAMAZOUZT.pdf.
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Au cours de cette étude sur l'alimentation artificielle de la perche perca fluviatilis élevée en milieu contrôlé, nous avons précisé l'intérêt de ses potentialités zootechniques et mis en évidence que: les larves acceptent une alimentation composée pendant les 15 premiers jours de leur vie avec un taux de survie maximal de 26%. Pendant les 10 jours qui suivent l'éclosion, une distribution des particules alimentaires d'une taille inferieure à 125 m, améliore les taux de croissance et de survie des larves. Ces aliments semblent mieux détectés dans des bassins à parois internes claires et sous un éclairage de 800 lux. Pour les juvéniles préalablement élevés en étang, l'adaptation à leur nouveau milieu est intimement liée à la nature de l'alimentation. Une phase transitoire à base de foie de buf haché double le taux de survie de ces perches par rapport à un passage direct à l'aliment artificiel. Une ration journalière de 2% du poids vif convient pour une bonne croissance des perches (20-22g) élevées à 18-20c en circuit fermé ; elle engendre cependant une élévation du coefficient de variation pondéral, lui-même lie au dimorphisme sexuel. Des taux de rationnement de 4 et 6% n'améliorent ni la croissance, ni la composition corporelle des perches. En cage flottante, une ration de 3% semble plus appropriée. Quoiqu'il en soit, les gains de poids des perches élevées en circuit fermé ou en cages flottantes ne sont pas significativement différents. Chez les perches élevées en cages, l'induction gonadosomatique est essentiellement attribuée à la variation de température. Le déclenchement de la maturité sexuelle provoque une involution des indices hepatosomatiques et modifie la composition corporelle. Les perches élevées en circuit ferme sont plus riches en triglycérides et plus pauvres en phospholipides et en protéines que celles issues des cages.
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Hirsch, Philipp E. "Phenotypic Processes Triggered by Biological Invasions." Doctoral thesis, Uppsala universitet, Limnologi, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-158697.
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Individuals within a single population can vary widely in their phenotype e.g. in their body shape. These differences are an important source of biodiversity and they can precede evolutionary divergence within a population. In this thesis we use the biological invasion of the zebra mussels into Swedish lakes to investigate which processes create or maintain phenotypic diversity within populations of the two native fish species perch and roach and the mussel itself. Both fishes have specially adapted body shapes that depend on whether they feed in the near-shore or open-water habitat of lakes. This habitat-specific divergence was more pronounced in lakes with zebra mussels, probably because resources in both habitats were in higher supply due to the mussels’ effects on the lakes. Divergence in perch body shapes between habitats was also higher in lakes with a higher water clarity, suggesting that visual conditions can affect the resource use and thus also the expression of a habitat-specific body shape. When investigating the diversity of body shapes in the mussel itself we found that mussels from one lake changed their shell shape when exposed to different predators: fish predators induced a more elongated shell shape while crayfish predators induced a rounder shell. These specific shell shapes probably serve as two alternative predator defenses protecting the mussel from predation. We conclude that the availability and use of distinct resources is an important source of diversity within populations. Abiotic conditions can play a previously underappreciated role by promoting or impairing the use of the distinct resources thus affecting the divergence. The diversity of shell shapes we found in the zebra mussels complements our study by demonstrating that not only consumer responses to resources but also resources’ responses to predators can generate phenotypic diversity.
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Caminade, Véronique. "Recherches sur l'état nutritionnel de deux espèces de poissons de la retenue de Pareloup (Aveyron) le Gardon (Leuciscus rutilus L.) et la Perche (Perca fluviatilis L.)." Grenoble 2 : ANRT, 1986. http://catalogue.bnf.fr/ark:/12148/cb375964923.
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