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Rémi Chappaz - One of the best experts on this subject based on the ideXlab platform.

  • Patterns of change in zooplankton community structures and the selective feeding of Bleak, alburnus alburnus (L.) in the Serre Ponçon dam between 1980 and 1996
    Hydrobiologia, 1998
    Co-Authors: Rémi Chappaz, David Doucende, Roxane Barthelemy
    Abstract:

    The Serre Poncon reservoir, in the southern French alps, filled when the dam was completed in 1960. It has meso-eutrophic characteristics. Two hydrobiological studies carried out in 1980 and in 1996 showed interspecific variation in zooplankton and fish communities. A strong development of B. longirostris, D. brachyurum and C. pulchella, characteristic of eutrophic environments, was apparent in 1996, while the population of Daphnia longispina, which was dominant in 1980, had declined. At the same time, strong growth of the bleak alburnus alburnus, was observed. Research into prey selection over several seasons showed that prey size and density were often a determining factor for capture, e.g., in C. pulchella, D. longispina and C.v. vicinus. However, some small sized rare species such as B. longirostris were also much sought after.

  • The use of geostatistics to analyse data from an echo-integration survey of fish stock in Lake Sainte-Croix
    Fisheries Research, 1992
    Co-Authors: Jean Guillard, Daniel Gerdeaux, Guy Brun, Rémi Chappaz
    Abstract:

    Two echo-integration surveys were carried out in Lake Sainte-Croix with an interval of 14 months, and differences in the spatial distribution of the fish population are described. One survey was during, the other after, the spawning season of the bleak (alburnus alburnus (L.) ), which is the predominant pelagic fish in the lake. Different methods of calculation were used to estimate the average biomass: parametric and spatial statistics. The estimates are close, but only the geostatistical estimate provides a useful confidence interval less than 20% of the estimated mean. The geostatistical variograms can be processed following a linear or a spherical model. Knowledge of fish population distributions and of natural phenomena in the lake leads to the choice of the linear model. The linear variogram takes into account the heterogeneity of the spatial distribution of the fish population and the spatial correlation of the samples.

Eduardo Da Silva - One of the best experts on this subject based on the ideXlab platform.

  • Dietary traits of invasive bleak alburnus alburnus (Actinopterygii, Cyprinidae) between contrasting habitats in Iberian fresh waters
    Hydrobiologia, 2017
    Co-Authors: David Almeida, David H. Fletcher, Carlos Rangel, Emili García-berthou, Eduardo Da Silva
    Abstract:

    The bleak alburnus alburnus (L., 1758) is a limnophilic fish native to most of Europe. This cyprinid species is a successful invader in the Iberian Peninsula, where it threatens the highly endemic fish fauna. However, studies on bleak autoecology are scarce in this region, with few data on foraging strategies. The aim of this work was to compare the dietary traits of bleak populations between contrasting habitats in Iberian fresh waters. For this purpose, bleak were seasonally collected from the small River Gévora and the Sierra Brava Reservoir (Guadiana River Basin, southwestern Spain). As percentages of occurrence and ingested mass, plant material and planktonic Crustacea were the most important food categories in the river and the reservoir, respectively. The intake of pelagic prey was higher in the reservoir, especially during summer. Benthic prey, plant material and detritus were more consumed in the river, especially benthos and detritus during spring, whereas plant intake decreased during this season. Shannon index, as a measure of trophic diversity, was higher in the reservoir, except for spring. Overall results suggest that this wide trophic plasticity will facilitate the bleak invasion process throughout Mediterranean Europe, which poses a serious risk to its highly valuable native fish fauna.

  • dietary traits of invasive bleak alburnus alburnus actinopterygii cyprinidae between contrasting habitats in iberian fresh waters
    Hydrobiologia, 2017
    Co-Authors: David Almeida, David H. Fletcher, Carlos Rangel, Emili Garciaberthou, Eduardo Da Silva
    Abstract:

    The bleak alburnus alburnus (L., 1758) is a limnophilic fish native to most of Europe. This cyprinid species is a successful invader in the Iberian Peninsula, where it threatens the highly endemic fish fauna. However, studies on bleak autoecology are scarce in this region, with few data on foraging strategies. The aim of this work was to compare the dietary traits of bleak populations between contrasting habitats in Iberian fresh waters. For this purpose, bleak were seasonally collected from the small River Gevora and the Sierra Brava Reservoir (Guadiana River Basin, southwestern Spain). As percentages of occurrence and ingested mass, plant material and planktonic Crustacea were the most important food categories in the river and the reservoir, respectively. The intake of pelagic prey was higher in the reservoir, especially during summer. Benthic prey, plant material and detritus were more consumed in the river, especially benthos and detritus during spring, whereas plant intake decreased during this season. Shannon index, as a measure of trophic diversity, was higher in the reservoir, except for spring. Overall results suggest that this wide trophic plasticity will facilitate the bleak invasion process throughout Mediterranean Europe, which poses a serious risk to its highly valuable native fish fauna.

  • population traits of invasive bleak alburnus alburnus between different habitats in iberian fresh waters
    Limnologica, 2014
    Co-Authors: David Almeida, David H. Fletcher, Carlos Rangel, Paris V Stefanoudis, Eduardo Da Silva
    Abstract:

    The bleak alburnus alburnus (L.) is a cyprinid native to most of Europe, mainly inhabiting lentic environments. This fish species is a successful invader in the Iberian Peninsula, where it was first introduced to reservoirs as forage fish during the 1990s. Bleaks threaten the highly endemic Iberian fish fauna by means of trophic competition and hybridization. Yet, little is known about the environmental biology of bleaks in the Iberian Peninsula, particularly far from impounded waters. Thus, the aim of this work was to compare seasonal and gender variation of size structure, body condition and reproductive investment of bleaks between different habitats. Only sexually mature bleaks were seasonally collected and examined from the River Gevora and the Sierra Brava Reservoir (southwestern Spain) to assess more in-depth the adaptive capacity at the population level and the subsequent invasiveness. Bleak was an abundant species in the fish assemblages of both habitat types (i.e. river and reservoir). The proportion of smaller mature bleaks was lower in the river than the reservoir during spring and the opposite pattern was observed during winter. Both male and females were larger in the river during the breeding season in the study areas (i.e. spring), as well as with higher body condition and reproductive investment. These findings suggest that bleaks enhance their reproduction rate in the river to compensate for higher mortality in this habitat, where environmental conditions may be harsher due to the winter floods and summer droughts typical of Mediterranean water courses. Overall results highlight the high degree of plasticity in population traits of the bleak in the Iberian Peninsula, which will surely aid its ability to adapt to a wide variety of Mediterranean ecosystems, including lentic and lotic environments. Consequently, this invasive fish may pose a serious risk for the highly valuable fauna of Mediterranean Europe.

Jan Kubečka - One of the best experts on this subject based on the ideXlab platform.

  • Sexual segregation in European cyprinids: consequence of response to predation risk influenced by sexual size dimorphism
    Hydrobiologia, 2020
    Co-Authors: Jakub Žák, Jiří Peterka, Marie Prchalová, Jaromír Seďa, Petr Blabolil, Mojmír Vašek, Josef Matěna, Marek Šmejkal, Milan Říha, Jan Kubečka
    Abstract:

    Fish respond to predation threat by size/cohort-dependent presence in particular habitats and this may contribute to sexual segregation between habitats in species with sexual size dimorphism (SSD). The present study examines the validity of the “predation risk hypothesis” and importance of SSD on habitat (pelagic/inshore) segregation and dietary differences between sexes in three cyprinids with various magnitudes of SSD-roach ( Rutilus rutilus ), freshwater bream ( Abramis brama ) and bleak ( alburnus alburnus ). Fish were sampled using gillnets over five consecutive years in the Římov Reservoir. Habitat segregation with female overrepresentation in the pelagic habitat was found in the most sexually dimorphic species with 26% bigger females—the roach. When analysis of habitat segregation was size-controlled, this segregation ceased to confirm the importance of SSD. Freshwater bream sexes (2% SSD) differed in diet but did not differ in habitat occupation. Bleak sexes were not segregated. Larger roach individuals (predominantly females) are less threatened by gape-limited predators and consequently they can occupy the risky but optimal (for zooplankton acquisition) pelagic habitat. Our results demonstrate that habitat segregation is present in the species with the most pronounced SSD.

  • Nocturnal spawning as a way to avoid egg exposure to diurnal predators
    Nature Publishing Group, 2018
    Co-Authors: Marek Šmejkal, Lukáš Vejřík, Petr Blabolil, Allan T. Souza, Daniel Bartoň, Zuzana Sajdlová, Jan Kubečka
    Abstract:

    Abstract Animals that do not provide parental care have to secure the survival of their offspring by ensuring a safe reproductive environment or smart timing tactics. Nocturnal spawning behaviour of many fish species is an example of the latter behaviour in the animal kingdom and is hypothesized to provide a survival advantage to the eggs spawned during the night. In order to test the efficiency of the smart timing tactics in a freshwater fish, a study was carried out of the interaction of the rheophilic spawner (asp Leuciscus aspius) and the predator of its drifting eggs (bleak alburnus alburnus) using passive telemetry. According to a model based on acquired data, asp laid 63% of its eggs at night, while vision-oriented bleak was present in 92% of the time during the day. This study gives support to the predator avoidance hypothesis, which expects animals to reproduce in a period when the probability of offspring predation is at its lowest

  • The gut contents of cyprinids from the Vír Reservoir in 2010 and 2011.
    2016
    Co-Authors: Lukáš Vejřík, Jaroslava Frouzová, Ivana Matějíčková, Jaromír Seďa, Petr Blabolil, Tomáš Jůza, Mojmír Vašek, Daniel Ricard, Josef Matěna, Jan Kubečka
    Abstract:

    The caught cyprinids were: common bream (Abramis brama), common carp (Cyprinus carpio), bleak (alburnus alburnus) and roach (Rutilus rutilus). No common carp were caught in 2011. The gut content was divided into five categories: YOY fish (dashed), Zooplankton (grey), Insect and Zoobenthos (black), Planktonic Cyanobacteria (white), and Detritus (dotted).

  • in situ diel patterns of zooplankton consumption by subadult adult roach rutilus rutilus bream abramis brama and bleak alburnus alburnus
    Folia Zoologica, 2004
    Co-Authors: Mojmír Vašek, Jan Kubečka
    Abstract:

    Diel feeding patterns of subadult and adult cyprinids of three species (roach Rutilus rutilus, bream Abramis brama, bleak alburnus alburnus), which foraged almost exclusively on microcrustacean plankton, were studied in the meso-eutrophic Rimov Reservoir (Czech Republic). All cyprinids showed a daytime feeding periodicity, with a marked night-time decline in gut fullness. Diel variations in gut fullness were observed in roach 200-270 mm standard length (SL) and bream 220-330 mm SL during May and in bleak, roach and bream of 110-170 mm SL, respectively, during August. Our results corroborate other studies in which light intensity has been found to be an important factor affecting cyprinid foraging on zooplankton. Daily zooplankton consumption rates ranged from 1.5 % of wet body weight in bream (220-330 mm SL) to 9.9 % of wet body weight in bleak (110-170 mm SL).

Csaba Szekely - One of the best experts on this subject based on the ideXlab platform.

  • myxobolus erythrophthalmi sp n and myxobolus shaharomae sp n myxozoa myxobolidae from the internal organs of rudd scardinius erythrophthalmus l and bleak alburnus alburnus l
    Journal of Fish Diseases, 2009
    Co-Authors: Kalman Molnar, Edit Eszterbauer, Szilvia Marton, Gabor Cech, Csaba Szekely
    Abstract:

    During a survey of myxosporean parasites of cyprinid fish in Hungary, infections caused by unknown Myxobolus spp. were found in the internal organs of rudd, Scardinius erythrophthalmus, and bleak, alburnus alburnus. Small plasmodia developed in blood vessels of the kidney, liver, testes and intestinal wall. The parasites were studied on the basis of spore morphology and by histological and molecular methods. In most cases, plasmodia were surrounded by host tissue without a host reaction; however, in advanced cases, a connective tissue capsule was seen around plasmodia. Spores collected from the two fish species differed from each other and from the known Myxobolus spp. both in their morphology and 18S rDNA sequences. The two species, described as M. erythrophthalmi sp. n. from rudd and M. shaharomae sp. n. from bleak, are characterized by a specific histotropism to blood vessels, while the organ specificity involves the kidney and for the latter species, most internal organs.

  • Myxobolus species infecting the cartilaginous rays of the gill filaments in cyprinid fishes
    Acta Parasitologica, 2008
    Co-Authors: Kalman Molnar, Gabor Cech, Csaba Szekely
    Abstract:

    During a survey on myxosporean parasites of cyprinid fishes in Hungary, Myxobolus infections were found in the cartilaginous rays of the gill filaments in roach ( Rutilus rutilus ) and bleak (alburnus alburnus). Myxobolus spp. causing the infections were studied by morphological, histological and molecular methods. Small plasmodia surrounded by chondrocytes contained relatively few spores which differed from each other and from the known Myxobolus spp. both in their morphology and 18S rDNA sequences. Both species, described as M. feisti sp. nov. and M. susanlimae sp. nov., are characterised by a specific cartilaginous histotropism.

Kalman Molnar - One of the best experts on this subject based on the ideXlab platform.

  • myxobolus erythrophthalmi sp n and myxobolus shaharomae sp n myxozoa myxobolidae from the internal organs of rudd scardinius erythrophthalmus l and bleak alburnus alburnus l
    Journal of Fish Diseases, 2009
    Co-Authors: Kalman Molnar, Edit Eszterbauer, Szilvia Marton, Gabor Cech, Csaba Szekely
    Abstract:

    During a survey of myxosporean parasites of cyprinid fish in Hungary, infections caused by unknown Myxobolus spp. were found in the internal organs of rudd, Scardinius erythrophthalmus, and bleak, alburnus alburnus. Small plasmodia developed in blood vessels of the kidney, liver, testes and intestinal wall. The parasites were studied on the basis of spore morphology and by histological and molecular methods. In most cases, plasmodia were surrounded by host tissue without a host reaction; however, in advanced cases, a connective tissue capsule was seen around plasmodia. Spores collected from the two fish species differed from each other and from the known Myxobolus spp. both in their morphology and 18S rDNA sequences. The two species, described as M. erythrophthalmi sp. n. from rudd and M. shaharomae sp. n. from bleak, are characterized by a specific histotropism to blood vessels, while the organ specificity involves the kidney and for the latter species, most internal organs.

  • Myxobolus species infecting the cartilaginous rays of the gill filaments in cyprinid fishes
    Acta Parasitologica, 2008
    Co-Authors: Kalman Molnar, Gabor Cech, Csaba Szekely
    Abstract:

    During a survey on myxosporean parasites of cyprinid fishes in Hungary, Myxobolus infections were found in the cartilaginous rays of the gill filaments in roach ( Rutilus rutilus ) and bleak (alburnus alburnus). Myxobolus spp. causing the infections were studied by morphological, histological and molecular methods. Small plasmodia surrounded by chondrocytes contained relatively few spores which differed from each other and from the known Myxobolus spp. both in their morphology and 18S rDNA sequences. Both species, described as M. feisti sp. nov. and M. susanlimae sp. nov., are characterised by a specific cartilaginous histotropism.

  • survey on myxobolus infection of the bleak alburnus alburnus l in the river danube and in lake balaton
    Acta Veterinaria Hungarica, 2000
    Co-Authors: Kalman Molnar
    Abstract:

    In a three-year survey of myxosporean infections of the bleak (alburnus alburnus), involving the examination of 205 fish specimens from the River Danube and 50 from Lake Balaton, four Myxobolus species (two gill parasites, one fin parasite and a species parasitising the skeletal muscles) were detected. Two of the species could be identified as M. alburni and M. obesus. Of the other two species, the gill parasite proved to be a hitherto undescribed species which is described here as a new species by the name of M. margitae. One of the two gillparasitic species, M. obesus, formed plasmodia in the respiratory lamellae of the gill filaments, while the plasmodia of M. margitae n. sp. were formed in the afferent artery of the primary gill filaments. The plasmodia containing spores morphologically identifiable with the species M. alburni were located in the connective tissue between the fin rays. The less frequently found muscle-parasitic Myxobolus species has not been identified precisely. The plasmodia of M. o...