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Fluviatilis L. (fluviatili + l)

Distribution by Scientific Domains
Life Sciences73%

Kinds of Fluviatilis L.

  • perca fluviatili l.
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    Selected Abstracts

    Spawning site selection by Eurasian perch (Perca fluviatilis L.) in relation to temperature and wave exposure

    ECOLOGY OF FRESHWATER FISH, Issue 1 2009
    W. N. Probst
    Abstract,,, The selection of spawning depth by Eurasian perch Perca fluviatilis was investigated in an experiment using artificial substrata in Lake Constance during the spawning season of 2007. The experiment compared spawning behaviour at substrata between 0.5 and 15 m depth at two sites exposed to different regimes of ship-generated wave action. The total abundance of egg ribbons did not differ significantly between the two sites, but the preferred spawning depth was deeper at the wave exposed site (5 m) compared to the sheltered site (2 m). While water temperatures could not account for the observations, differences in wave exposure may explain the different spawning depth preferences. At both sites, large egg ribbons were generally found in deeper water, and large egg ribbons occurred more frequently at the sheltered site. Because the egg ribbons of perch are likely to have a size-dependent susceptibility to hydrodynamic stress, large females may be expected to select deeper spawning locations where the effects of surface waves are considerably attenuated. [source]

    Effects of predator-induced visual and olfactory cues on 0+ perch (Perca fluviatilis L.) foraging behaviour

    ECOLOGY OF FRESHWATER FISH, Issue 2 2006
    V. N. Mikheev
    Abstract,,, Foraging juvenile fish with relatively high food demands are usually vulnerable to various aquatic and avian predators. To compromise between foraging and antipredator activity, they need exact and reliable information about current predation risk. Among direct predator-induced cues, visual and olfactory signals are considered to be most important. Food intake rates and prey-size selectivity of laboratory-reared, naive young-of-the-year (YOY) perch, Perca fluviatilis, were studied in experiments with Daphnia magna of two size classes: 2.8 and 1.3 mm as prey and northern pike, Esox lucius, as predator. Neither total intake rate nor prey-size selectivity was modified by predator kairomones alone (water from an aquarium with a pike was pumped into the test aquaria) under daylight conditions. Visual presentation of pike reduced total food intake by perch. This effect was significantly more pronounced (synergistic) when visual and olfactory cues were presented simultaneously to foraging perch. Moreover, the combination of cues caused a significant shift in prey-size selection, expressed as a reduced proportion of large prey in the diet. Our observations demonstrate that predator-induced olfactory cues alone are less important modifiers of the feeding behaviour of naive YOY perch than visual cues under daylight conditions. However, pike odour acts as a modulatory stimulus enhancing the effects of visual cues, which trigger an innate response in perch. [source]

    Predation risk allocation or direct vigilance response in the predator interaction between perch (Perca fluviatilis L.) and pike (Esox lucius L.)?

    ECOLOGY OF FRESHWATER FISH, Issue 3 2005
    A. Vainikka
    Abstract , Predation risk allocation hypothesis predicts that a prey's response to predator depends on prey's previous experience on predator. Here we tested whether the group of three perch respond differentially to pike, predator of perch, depending on the timing of high constant (HC) and high unpredictable (HU) risk periods within low constant risk periods in short-term (10 h) experiments, and whether the response is stronger during a HU risk period than during a HC risk period. Perch clearly erected the dorsal fin in response to predation risk treatments (pike odour only, odour and visible pike). Decrease in activity and increase in shoaling behaviour were observed mainly during high risk periods. However, the perch's responses to pike did not differ statistically between periods of various levels of predation risk or depending on the timing of high risk situations within constant low risk periods, and thus, suggesting that perch respond mainly to changes in the current predation risk. Resumen 1. La hipótesis de la asignación de riesgo a la predación predice que la respuesta a un predador depende de la experiencia previa de la presa al predador. En este trabajo analizamos si un grupo de tres individuos de Perca fluviatilis respondían de forma distinta a la presencia de Esox lucius, (un predador común de esta especie) y si éstas dependían del momento en el que se producen periodos de alto riesgo constante y de alto riesgo impredecible, en experimentos de corto plazo (10 horas) de riesgo bajo y constante y si la respuesta era mayor durante perí odos de riesgo impredecible y alto que durante períodos de riesgo constante alto. 2. Claramente P. fluviatilis respondió levantando la aleta dorsal en respuesta a los tratamientos de riesgo a la predación (solamente olor y olor + visibilidad de E. lucius). Una menor actividad y una mayor tendencia a la formación de bancos fueron observados durante períodos de alto riesgo. Sin embargo, las respuesta de P. fluviatilis a E. lucius no difirieron estadísticamente entre períodos de varios niveles de riesgo a la predación o entre aquellos que dependieron del momento en el que se produjeron situaciones de alto riesgo dentro de períodos de bajo riesgo constante. 3. Concluimos que P. fluviatilis puede utilizar señales olfatorias como determinantes de respuestas al riesgo a la predación y responder a aumentos de riesgo, sin excluir la posibilidad de que amenazas repetidas decrezcan la intensidad de la respuesta. Nuestros resultados, obtenidos en experimentos realizados a pequeña escala temporal, no niegan la posibilidad de la P. fluviatilis y otras especies puedan balancear la alimentación con actividades anti-predación, de acuerdo a cambios en el riesgo de predación a lo largo de escalas temporales de varios días. [source]

    Competition for food between Eurasian perch (Perca fluviatilis L.) and ruffe (Gymnocephalus cernuus [L.]) over different substrate types

    ECOLOGY OF FRESHWATER FISH, Issue 4 2004
    A. Dieterich
    Abstract,,, Food consumption by Eurasian perch (Perca fluviatilis L.) and ruffe (Gymnocephalus cernuus [L.]) was studied in single and mixed-species treatments in the laboratory, where alternative food resources, chironomids and zooplankton, were offered simultaneously. The effects of structural complexity, which was represented by substrate grain size, and of feeding level on food consumption were analysed. Across all experiments, the outcome of competition between perch and ruffe depended on food abundance and on the structural complexity of the environment. Perch and ruffe both changed their food consumption in the presence of a heterospecific competitor. With high food supply, perch consumed more benthic food than ruffe. With low food supply, the consumption of perch decreased strongly, while that of ruffe remained high on fine sediment. Under all conditions tested, the mechanism of competition appeared to be of interference rather than of exploitative nature. It is suggested that with decreasing lake productivity caused by re-oligotrophication, habitat shifts of both species will occur, which will alleviate interspecific competition. Ruffe will forage over fine sediment and perch over coarse sediment, whereby both species will achieve the highest foraging efficiency under conditions of low food supply. Resumen 1. Hemos estudiado el consumo alimenticio de Perca fluviatilis L. y Gymnocephalus cernuus (L.) en condiciones de laboratorio. Bajo tratamientos de especies individuales y mezcladas, les ofrecimos, simultáneamente, varios recursos alimenticios alternativos (quironómidos y zooplancton). 2. Analizamos los efectos de la complejidad estructural - representada por el tamaño del sustrato (arena, grava, y guijo) - y del nivel alimenticio, sobre el consumo alimenticio. Pusimos especial atención a la potencial influencia de competidores hetero-específicos sobre los patrones alimenticios de ambas especies, tanto en términos cualitativos como cuantitativos. Además, dado que en un futuro cercano una menor productividad general en lagos debida a re-oligotrofia, probablemente aumente la competición por el alimento en muchos lagos donde ambas especies co-existen, los experimentos se llevaron a cabo bajo niveles de abastecimiento alimenticio alto y bajo. 3. En los experimentos, la aparición de competencia entre P. fluviatilis y G. cernuus dependió de la abundancia del alimento y de la complejidad estructural del ambiente. El consumo de quironómidos por P. fluviatilis dependió del tipo de sustrato a niveles altos de abastecimiento alimenticio pero no a niveles bajos, mientras que en G. cernuus observamos lo contrario. 4. Ambas especies cambiaron el consumo alimenticio en presencia de un competidor hetero-específico. A altos niveles de abastecimiento alimenticio, P. fluviatilis consumió más bentos que G. cernuus. A niveles bajos, el consumo de P. fluviatilis decreció substancialmente mientras que el de G. cernuus permaneció alto en sedimento fino. Bajo todas las condiciones experimentales analizadas, los mecanismos de competición parecieron ser de interferencia más que de naturaleza explotativa. 5. Finalmente, presentamos un escenario sobre como P. fluviatilis y G. cernuus pueden competir por alimento bentónico en lagos con variado sustrato de fondo. Sugerimos que a altos niveles de abastecimiento alimenticio, G. cernuus forrajee más sobre arena y grava mientras que P. fluviatilis puede utilizar todos los sustratos disponibles. Al decrecer el abastecimiento alimenticio por re-oligotrofia, pueden producirse cambios en el hábitat de ambas especies que minimizarán la competencia inter-específica. G. cernuus forrajeará básicamente sobre sedimento fino, allá donde sea claramente superior a P. fluviatilis. Esta última especie forrajeará predominantemente sobre sedimento más grueso donde se enfrentará a competencia intra- e inter-específica. A través de estos cambios de hábitat, ambas especies podrían alcanzar la mayor eficiencia de forrajeo bajo condiciones de bajo abastecimiento alimenticio. [source]

    Is scuba sampling a relevant method to study fish microhabitat in lakes?

    ECOLOGY OF FRESHWATER FISH, Issue 3 2001
    Examples, comparisons for three European species
    Abstract , We compared fish microhabitat use patterns in the littoral zone of a lake using a new direct method (point abundance sampling by scuba, PASS) and the widely used point abundance sampling by electrofishing technique (PASE). We collected microhabitat data for age 0+ roach (Rutilus rutilus L.), perch (Perca fluviatilis L.), and pike (Esox lucius L.). The two methods yielded different results for fish assemblage structure and microhabitat patterns. Using PASE, fish were mainly found in "shelter habitats" such as shallow waters and dense vegetation. It is likely that this behavior is caused by the disturbance of the observer stamping around. Using PASS, fish escapement behavior was rarely observed. Therefore, we concluded that this direct and nondestructive sampling technique can be used to provide an accurate microhabitat estimation of a fish community and is assumed to be more suitable than PASE for fish habitat studies., [source]

    CRYPTIC BARRIERS TO DISPERSAL WITHIN A LAKE ALLOW GENETIC DIFFERENTIATION OF EURASIAN PERCH

    EVOLUTION, Issue 8 2007
    S. Bergek
    Gene flow between coexisting or nearby populations normally prevents genetic divergence and local adaptation. Despite this, there are an increasing number of reports of sympatric sister taxa, indicating potential divergence and speciation in the face of gene flow. A large number of such reported cases involve lake-dwelling fish, which are expected to run into few physical barriers to dispersal within their aquatic habitat. However, such cases may not necessarily reflect sympatric speciation if cryptic dispersal barriers are common in lakes and other aquatic systems. In this study, we examined genetic differentiation in perch (Perca fluviatilis L.) from nine locations in a single, small lake (24 km2), using microsatellites. We detected significant genetic differentiation in all but two pairwise comparisons. These patterns were not consistent with divergence by distance or the existence of kin groups. Instead, they suggest that cryptic barriers to dispersal exist within the lake, allowing small-scale genetic divergence. Such an observation suggests that allopatric (or parapatric) divergence may be possible, even in small, apparently homogenous environments such as lakes. This has important consequences for how we currently view evidence from nature for sympatric speciation. [source]

    Does high nitrogen loading prevent clear-water conditions in shallow lakes at moderately high phosphorus concentrations?

    FRESHWATER BIOLOGY, Issue 1 2005
    María A. González Sagrario
    Summary 1. The effect of total nitrogen (TN) and phosphorus (TP) loading on trophic structure and water clarity was studied during summer in 24 field enclosures fixed in, and kept open to, the sediment in a shallow lake. The experiment involved a control treatment and five treatments to which nutrients were added: (i) high phosphorus, (ii) moderate nitrogen, (iii) high nitrogen, (iv) high phosphorus and moderate nitrogen and (v) high phosphorus and high nitrogen. To reduce zooplankton grazers, 1+ fish (Perca fluviatilis L.) were stocked in all enclosures at a density of 3.7 individuals m,2. 2. With the addition of phosphorus, chlorophyll a and the total biovolume of phytoplankton rose significantly at moderate and high nitrogen. Cyanobacteria or chlorophytes dominated in all enclosures to which we added phosphorus as well as in the high nitrogen treatment, while cryptophytes dominated in the moderate nitrogen enclosures and the controls. 3. At the end of the experiment, the biomass of the submerged macrophytes Elodea canadensis and Potamogeton sp. was significantly lower in the dual treatments (TN, TP) than in single nutrient treatments and controls and the water clarity declined. The shift to a turbid state with low plant coverage occurred at TN >2 mg N L,1 and TP >0.13,0.2 mg P L,1. These results concur with a survey of Danish shallow lakes, showing that high macrophyte coverage occurred only when summer mean TN was below 2 mg N L,1, irrespective of the concentration of TP, which ranged between 0.03 and 1.2 mg P L,1. 4. Zooplankton biomass and the zooplankton : phytoplankton biomass ratio, and probably also the grazing pressure on phytoplankton, remained overall low in all treatments, reflecting the high fish abundance chosen for the experiment. We saw no response to nutrition addition in total zooplankton biomass, indicating that the loss of plants and a shift to the turbid state did not result from changes in zooplankton grazing. Shading by phytoplankton and periphyton was probably the key factor. 5. Nitrogen may play a far more important role than previously appreciated in the loss of submerged macrophytes at increased nutrient loading and for the delay in the re-establishment of the nutrient loading reduction. We cannot yet specify, however, a threshold value for N that would cause a shift to a turbid state as it may vary with fish density and climatic conditions. However, the focus should be widened to use control of both N and P in the restoration of eutrophic shallow lakes. [source]

    Growth rate constrain morphological divergence when driven by competition

    OIKOS, Issue 1 2006
    Jens Olsson
    Resource competition has been hypothesized to be important in driving divergence by natural selection. The effect of competition on morphological divergence and plasticity has however rarely been investigated. Since low growth rates might constrain morphological modulation and individual growth rates usually are negatively related to the intensity of competition, there might be a connection between competition, growth rate and morphological divergence. We performed an aquarium experiment with young-of-the-year Eurasian perch (Perca fluviatilis L.) to investigate how individual growth rate affected morphological plasticity induced by contrasting habitat treatments. Furthermore, in a field study of 10 lakes we also related the degree of morphological differentiation between habitats to the intraspecific competitior biomass. In the aquarium experiment we found that morphological plasticity was growth rate dependent in that morphological differentiation between the habitat treatments was confined to high individual growth rates. In the field study we found that morphological differentiation between habitats decreased with increasing intraspecific competitior biomass. Since plasticity is hypothesized to be important in divergence and intraspecific biomass could serve as a proxy for the level of competition, we suggest that our results indicate that morphological divergence might be constrained during periods of intense intraspecific competition due to low growth rates. A possible scenario is that at low growth rates all energy available is used for metabolic maintenance and no surplus energy is therefore available for morphological modulation. [source]

    SHORT COMMUNICATION: Effects of hormonal treatments on induced tank spawning of Eurasian perch (Perca fluviatilis L.)

    AQUACULTURE RESEARCH, Issue 9 2010
    András Rónyai
    No abstract is available for this article. [source]

    Size-related oxygen consumption and ammonia excretion of Eurasian perch (Perca fluviatilis L.) reared in a recirculating system

    AQUACULTURE RESEARCH, Issue 1 2009
    Vlastimil Stejskal
    Abstract Oxygen consumption (OC) and ammonia excretion rates (AE) of perch were measured under commercial-like conditions (temperature 23.3 °C) in both fed (F) and feed-deprived groups (D). Measurements were taken in triplicate in six sized batches of perch ranging from 44.8 to 336.2 g. The mean daily OC was 288.3,180.6 mg O2 kg,1 h,1 for group F fish ranging in size from 44.8 to 279.4 g body weight. The mean daily AE expressed as total ammonia nitrogen (TAN) was 13.8,5.2 mg TAN kg,1 h,1 in the same groups. Daily peaks of OC in group F perch were observed 6 h after the onset of feeding for each size group with relatively stable values up to the end of feeding. Peaks of daily AE in group F perch were observed 10 h after the onset of feeding in each size group, with a rapid decrease up to 16 h after onset. In group D, OC was 181.1,110.5 mg O2 kg,1 h,1 in the weight range 57.9,336.2 g. The daily mean AE was 1.7,0.5 TAN kg,1 h,1 in this group. No dramatic peaks of OC and AE were observed in group D perch. [source]

    Comparison of the effects of four anaesthetics on biochemical blood profiles of perch

    AQUACULTURE RESEARCH, Issue 3 2009
    Josef Velí
    Abstract This study investigated the feasibility of using clove oil, 2-phenoxyethanol, or Propiscin as an alternative to tricaine methane sulphonate (MS 222) as a fish anaesthetic, particularly in regard to reducing fish stress. The biochemical blood profiles of perch Perca fluviatilis L. anaesthetized with either MS 222 (100 mg L,1), clove oil (33 mg L,1), 2-phenoxyethanol (0.40 mL L,1) or Propiscin (1.0 mL L,1), and a non-anaesthetized control group were compared. Biochemical profiles were determined from blood samples collected before treatment in controls. For each anaesthetic tested, fish were divided into two groups, one sampled immediately after 10-min anaesthesia and a second, sampled 24 h after 10-min anaesthesia. The values determined in the present study suggested that internal organs and tissues of perch were slightly altered by MS 222, clove oil and 2-phenoxyethanol anaesthesia, but not by Propiscin anaesthesia. [source]

    Weaning of juvenile pikeperch, Stizostedion lucioperca L., and perch, Perca fluviatilis L., to formulated feed

    AQUACULTURE RESEARCH, Issue 4 2003
    L Ljunggren
    Abstract Weaning success of pond-cultured pikeperch and wild-caught perch (mean length 51 and 48 mm respectively) was evaluated using different weaning techniques and different formulated feeds. Juveniles that were fed formulated feed grew as well as or better than juveniles that were weaned successively using zooplankton or yolk. Four different formulated feeds (agglomerated marine larvae feed, marine larvae feed, trout feed and a semi-moist feed) were evaluated regarding specific growth rate (SGR), condition factor and a subjective stomach fullness estimate. The agglomerated marine larvae feed gave significantly better weaning performance than the other feeds regarding all parameters (SGR = 7.3% day,1 and 3.4% day,1 for pikeperch and perch respectively). [source]

    Genetic and morphological divergence reveals local subdivision of perch (Perca fluviatilis L.)

    BIOLOGICAL JOURNAL OF THE LINNEAN SOCIETY, Issue 4 2009
    SARA BERGEK
    The level of gene flow is an important factor influencing genetic differentiation between populations. Typically, geographic distance is considered to be the major factor limiting dispersal and should thus only influence the degree of genetic divergence at larger spatial scales. However, recent studies have revealed the possibility for small-scale genetic differentiation, suggesting that the spatial scale considered is pivotal for finding patterns of isolation by distance. To address this question, genetic and morphological differentiation were studied at two spatial scales (range 2,13 km and range 300 m to 2 km) in the perch (Perca fluviatilis L.) from the east coast archipelago of Sweden, using seven microsatellite loci and geometric morphometrics. We found highly significant genetic differentiation between sampled locations at both scales. At the larger spatial scale, the distance per se was not affecting the level of divergence. At the small scale, however, we found subtle patterns of isolation by distance. In addition, we also found morphological divergence between locations, congruent with a spatial separation at a microgeographic scale, most likely due to phenotypic plasticity. The present study highlights the importance of geographical scale and indicates that there might be a disparity between the dispersal capacity of a species and the actual movement of genes. Thus, how we view the environment and possible barriers to dispersal might have great implications for our ability to fully understand the evolution of genetic differentiation, local adaptation, and, in the end, speciation. © 2009 The Linnean Society of London, Biological Journal of the Linnean Society, 2009, 96, 746,758. [source]