Libor Závorka

Libor Závorka
Wasser Cluster Lunz · LIPTOX

Ph.D.

About

43
Publications
12,673
Reads
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419
Citations
Introduction
I am a behavioural ecologist with interest in examining how individuals’ cognition and behaviour influence life-history trade-offs between growth, reproduction and survival. I am also interested in invasion biology, and I study how phenotypic differences between individuals of an invasive species can impact the recipient ecosystem. I currently hold a position of a post-doctoral fellow in the LIPTOX group at WasserCluster Lunz, Austria.
Additional affiliations
February 2016 - February 2018
Paul Sabatier University - Toulouse III
Position
  • PostDoc Position
April 2013 - July 2015
University of Gothenburg
Position
  • PhD internship
Description
  • Behavioural ecology of salmonid fish (Salmonid Ecology Group). Active participant in the European ERA-NET Biodiversa project SALMOINVADE. Field of interest Behavioural ecology of fish, biological invasions.
September 2010 - January 2015
T.G. Masaryk Water Research Institute
Position
  • Researcher
Education
October 2011 - November 2015
Charles University in Prague
Field of study
  • Density-dependent effects of mutual familiarity on individuals and population structure in brown trout (Salmo trutta).
October 2006 - May 2011
Charles University in Prague
Field of study
  • ecology

Publications

Publications (43)
Article
Full-text available
While there is a long-history of biological invasions and their ecological impacts have been widely demonstrated across taxa and ecosystems, our knowledge on the temporal dynamic of these impacts remains extremely limited. Using a meta-analytic approach, we investigated how the ecological impacts of non-native brown trout (Salmo trutta), a model sp...
Article
Full-text available
Reducing the abundances of invasive species by removals aims to minimize their ecological impacts and enable ecosystem recovery. Removal methods are usually selective, modifying phenotypic traits in the managed populations. However, there is little empirical evidence of how removal-driven changes in multiple phenotypic traits of surviving individua...
Article
Full-text available
In recent decades, much conceptual thinking in trophic ecology has been guided by theories of nutrient limitation and the flow of elements, such as carbon and nitrogen, within and among ecosystems. More recently, ecologists have also turned their attention to examining the value of specific dietary nutrients, in particular polyunsaturated fatty aci...
Article
Full-text available
1. Omega‐3 long‐chain polyunsaturated fatty acids (n‐3 LC‐PUFA) are essential micronutrients for optimal functioning of cellular metabolism and for somatic growth of all vertebrates including fishes. In addition, n‐3 LC‐PUFA could also play a key role in response of fishes and other ectothermic vertebrates to changing temperatures. 2. An important,...
Article
Full-text available
Omega-3 long-chain polyunsaturated fatty acids (n-3 LC-PUFA) are key structural lipids and their dietary intake is essential for brain development of virtually all vertebrates. The importance of n-3 LC-PUFA has been demonstrated in clinical and laboratory studies, but little is known about how differences in the availability of n-3 LC-PUFA in natur...
Article
Omega-3 long-chain polyunsaturated fatty acids (n-3 LC-PUFA) are essential micronutrients for aquatic consumers. Synthesized by aquatic primary producers, n-3 LC-PUFA are transferred across trophic levels and may eventually end up accumulating in fish. However, if short in dietary supply, fish may also biosynthesize n-3 LC-PUFA from dietary precurs...
Article
Full-text available
Methods for identifying origin, movement, and foraging areas of animals are essential for understanding ecosystem connectivity, nutrient flows, and other ecological processes. Telemetric methods can provide detailed spatial coverage but are limited to a minimum body size of specimen for tagging. In recent years, stable isotopes have been increasing...
Article
Full-text available
Interference competition over food and territory can shape population structure and habitat use within and between species. The introduction of invasive species often leads to novel competitive interactions over shared resources and invaders can eventually exclude the native species from preferred habitats. Invasive brook trout (Salvelinus fontinal...
Article
Full-text available
It has been suggested that a trade‐off between cognitive capacity and developmental costs may drive brain size and morphology across fish species, but this pattern is less well explored at the intraspecific level. Physical habitat complexity has been proposed as a key selection pressure on cognitive capacity that shapes brain morphology of fishes....
Preprint
1. Omega-3 long-chain polyunsaturated fatty acids (n-3 LC-PUFA) are key structural lipids and their dietary intake is essential for brain development of virtually all vertebrates. The importance of n-3 LC-PUFA has been demonstrated in clinical and laboratory studies, but little is known about how differences in availability of n-3 LC-PUFA in natura...
Preprint
Full-text available
Omega-3 long-chain polyunsaturated fatty acids (n-3 LC-PUFA) are key structural lipids and their dietary intake is essential for brain development of virtually all vertebrates. The importance of n-3 LC-PUFA has been demonstrated in clinical and laboratory studies, but little is known about how differences in availability of n-3 LC-PUFA in natural p...
Article
Full-text available
Interest in the measurement of metabolic rates is growing rapidly, because of the importance of metabolism in advancing our understanding of organismal physiology, behaviour, evolution and responses to environmental change. The study of metabolism in aquatic animals is undergoing an especially pronounced expansion, with more researchers utilising i...
Article
Use of fast-growing domesticated and/or genetically-modified strains of fish is becoming increasingly common in aquaculture, increasing the likelihood of deliberate or accidental introductions into the wild. To date, their ecological impacts on ecosystems remain to be quantified. Here, using a controlled phenotype manipulation by implanting growth...
Article
Full-text available
Atlantic salmon are increasingly being released after capture by anglers. Yet, there are still unknown effects on the fish being subjected to the process of catch and release. Capture too close to spawning could have adverse effects on fish, and such data are important for setting appropriate closed seasons. This study examines how stressors relate...
Preprint
Full-text available
The trade-off between cognitive capacity and developmental costs drive brain size and morphology across fish species, but this pattern is less explored at intraspecific level. Physical habitat complexity has been proposed as a selection pressure on cognitive capacity that shapes brain morphology of fishes, but development of brain is also inherentl...
Preprint
Full-text available
Interest in the measurement of metabolic rates is growing rapidly, due to the relevance of metabolism in understanding organismal physiology, behaviour, evolution, and responses to environmental change. The study of metabolism in aquatic organisms is experiencing an especially pronounced expansion, with more researchers utilizing intermittent-close...
Article
Full-text available
While evidence suggests that warming may impact cognition of ectotherms, the underlying mechanisms remain poorly understood. A possible, but rarely considered mechanism is that metabolic response of ectotherms to warming associate with changes in brain morphology and functioning. Here we compared aerobic metabolism, volume of brain, boldness, and a...
Technical Report
Full-text available
Během technických zásahů byla zaznamenána průměrná mortalita u ryb 31 % a u zoobentosu 95 %. Pravděpodobnost úhynu vranek během pojezdu klesala s velikostí jedince, naopak u pstruhů nebyla závislá na velikosti jedince. Střední hodnota pohybů (bez ohledu na směr pohybu) u vranek a pstruhů byla během experimentu 10 m. U vranky pruhoploutvé a pstruha...
Article
Niche divergence resulting from coevolution is commonly believed to favour coexistence among competing species, however recent investigations have demonstrated that an unexpected niche convergence can occur when native and non-native species coexist. Yet, our understanding of the ontogenetic characteristics of this niche convergence remains limited...
Article
Full-text available
Competition with a non-native species can lead to morphological changes in native organisms induced by phenotypic plasticity, and by selection against individuals that do not adjust their morphology to the novel selection pressure. The morphological changes in native organisms are often associated with rapid behavioural responses to competition wit...
Article
Full-text available
Competition with a non-native species can lead to morphological changes in native organisms induced by phenotypic plasticity, and by selection against individuals that do not adjust their morphology to the novel selection pressure. The morphological changes in native organisms are often associated with rapid behavioural responses to competition wit...
Article
Full-text available
Phenotypic scoring of wild animals under standardized laboratory conditions is important as it allows field ecologists and evolutionary biologists to understand the development and maintenance of interindividual differences in plastic traits (e.g. behaviour and physiology). However, captivity is associated with a shift from a natural familiar envir...
Technical Report
Full-text available
Ačkoliv jsou malé vodní toky každoročně vystaveny celé řadě technických úprav, informace o dopadu použité těžké techniky na vodní toky jsou velmi kusé. Cílem studie bylo zhodnotit míru mortality vranky pruhoploutvé a pstruha obecného během těchto úprav, zároveň získat informace o jejich pohybech, dále posoudit vliv zásahů na společenstva zoobentosu...
Article
Full-text available
Selection induced by human harvest can lead to different patterns of phenotypic change than natural predation and could be a major driving force of evolution of wild populations. The vulnerability of individuals to angling depends on the individual decision to ingest the bait, possibly mediated by their neuroendocrine response towards the associate...
Article
Full-text available
Movement activity levels of wild animals often differ consistently among individuals, reflecting different behavioural types. Previous studies have shown that lab‐scored activity can predict several ecologically relevant characteristics. In an experiment on wild brown trout S. trutta, spanning from June to October, we investigated how spring swimmi...
Article
Full-text available
In freshwater streams, flooding is a typical source of natural disturbance that plays a key role in the dynamics of animal populations and communities. However, habitat degradation and fish stocking might increase the severity of its impact. We tested the effects of a flash flood on the abundance of three size classes of headwater dwelling Alpine b...
Article
Full-text available
Gill parasites on fish are likely to negatively influence their host by inhibiting respiration, oxygen transport capacity and overall fitness. The glochidia larvae of the endangered freshwater pearl mussel (FPM, Margaritifera margaritifera (Linnaeus, 1758)) are obligate parasites on the gills of juvenile salmonid fish. We investigated the effects o...
Article
Full-text available
1.A phenotypic syndrome refers to complex patterns of integration among functionally related traits in an organism that defines how the organism interacts with its environment and sustains itself. 2.Human-induced biological invasions have become important sources of environmental modifications. However, the extent to which invasive species affect...
Article
Full-text available
The hypothesis that interindividual differences in the activity of brown trout alter the exposure to parasitic freshwater pearl mussel glochidia was tested in a Swedish stream. Wild yearling brown trout (N = 103) were caught, individually tagged for identification and scored for open-field activity during standardized laboratory tests in June. Fift...
Article
Full-text available
Theory suggests that high activity levels in animals increase growth at the cost of increased mortality. This growth-mortality trade-off has recently been incorporated into the wider framework of the pace-of-life syndrome (POLS) hypothesis. However, activity is often quantified only in the laboratory and on a diurnal basis, leaving open the possibi...
Article
Full-text available
The deleterious effect of competition for space and food in animals increases with increasing population density. In contrast, familiarity towards conspecifics can relax the intensity of interference competition. Here, we hypothesized that familiarity towards conspecifics mitigates the effect of density-dependent growth and dispersal behaviour in t...
Article
Full-text available
In this paper we demonstrate that eggs from anadromous salmonines can constitute a large proportion of the dietary intake of individual juvenile Atlantic salmon Salmo salar and brown trout Salmo trutta during the spawning period in late autumn. The majority of fish older than 1 year residing on a spawning ground were found to have ingested eggs fr...
Article
Full-text available
This study focuses on the mechanism of density-dependent growth in a stream-dwelling landlocked population of brown trout Salmo trutta. Specifically, body growth estimated by scale reading was examined in relation to population density and recapture rate (approximation of persistence of individuals within a location associated with dispersal and mo...
Article
Full-text available
Theory suggests that consistent individual differences in activity are linked to life history where high activity is associated with rapid growth, high dispersal tendency, and low survival (the pace-of-life syndrome hypothesis). We addressed this influential hypothesis by combining behavioral studies with fine-scale positional scoring in nature, es...
Article
Full-text available
A demogenetic analysis based on 7 years of observation (2005–2011) was conducted to examine the population structure of brown trout Salmo trutta in pristine dendritic head-waters. The value of genetic divergence (F ST) among sampling units ranged from À0.03 to 0.16. Demographic syn-chrony was low or moderate, and the average correlation coefficient...
Technical Report
Full-text available
This methodology is intended for managers of watercourses, government agencies and investors aiming to help them to assess the influence of water management constructions and other artificial fish migration barriers on freshwater ecosystems. The method is mainly focused on the evaluation of restoration actions especially fish passes. The present me...
Article
Full-text available
Animals use dispersed resources within their home range (HR) during regular day-to-day activities. The high-quality area intensively used by an individual, where critical resources are concentrated, has been designated as the core area (CA). This study aimed to describe how animals utilize energy in the HR and CA assuming that changes would occur a...
Article
Full-text available
In this study, we validated a scale-reading method estimating age and growth in brown trout Salmo trutta in wild, landlocked, stream-dwelling populations from mountain headwaters in the Elbe catchment area of the Czech Republic. The values estimated from scale reading were compared with measured values, collected using a mark-recapture program over...
Article
Full-text available
Parasitic species can affect host behaviour in various ways. Freshwater mussels of the superfamily Unionoidea have a glochidia larva that is parasitic on fish. Our aim was to evaluate whether fish exposed to glochidia have distinct behaviour that could affect the upstream dispersal of the parasite.Many freshwater mussels are highly endangered, and...
Article
Full-text available
The majority of stream-dwelling salmonid populations in Europe are affected by artificial stocking and the fragmentation of riverine ecosystems. The present study was performed in the unique pristine headwaters of the Otava River in the Elbe catchment area of the Czech Republic. The aim was to investigate the spatial distribution and individual gro...

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Projects

Projects (5)
Project
The aim of the project is to use the framework of Tinbergen’s four essential questions to understand the mechanism through which dietary intake and internal synthesis n-3 LC-PUFA affects biochemical and cellular quality of brain and cognitive traits of brown trout. The project puts especially strong emphasis on ecologically relevant context of the research. Therefore, the laboratory and experimental work will be accompanied by extensive sampling of wild populations of brown trout and assessment of behaviour and fitness of focal fish in their natural river environment (e.g., by using radio telemetry and mark-recapture study design). The project PI is Dr. Libor Závorka (WasserCluster Lunz) and main project collaborators are Dr. Martin Kainz (WasserCluster Lunz), Dr. Pavel Němec (Charles Univesity in Prague), and Prof. Shaun Killen (University of Glasgow).
Project
The Cyprinidae is the largest family of freshwater fish with roughly 2500 species. This fish family includes species of great human interest - cultured carp forms, koi carps, color goldfishes, Prussian carps, veiltail goldfish, and many others. The status of Cyprinid fish varied around the world from nationally important fish species in Asia, through the farm fish and protected species in Europe to highly invasive species in North America and Australia. Our project will focus on the most common species in breeding aquaculture of Europe - Cyprinus carpio (common carp) and non-native species of the genus Carassius (European crucian carps). The project aims will lead to better knowledge about species food competitions in the fishponds with different intensity of farming. This bilateral cooperation includes a pilot study of stable isotope analysis in Slovak river basins. Output data will apply to the more effective management of aquaculture, invasive cyprinids management as well as surrounding aquatic ecosystems management.