
Libor ZávorkaWasser Cluster Lunz · SciFish
Libor Závorka
Ph.D.
About
53
Publications
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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 the SciFish group leader at WasserCluster Lunz, Austria.
Additional affiliations
February 2018 - January 2020
February 2016 - February 2018
September 2010 - January 2015
Publications
Publications (53)
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...
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...
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...
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...
The physiological dependence of animals on dietary intake of vitamins, amino
acids, and fatty acids is ubiquitous. Sharp differences in the availability of
these vital dietary biomolecules among different resources mean that consumers
must adopt a range of strategies to meet their physiological needs.We review the
emerging work on omega-3 long-chai...
Understanding the movement ecology and habitat use of freshwater fish is crucial for their conservation, with telemetry being an essential tool. Current tagging methods are restricted by the minimum body size of fish, as tags should not exceed 2% of the fish's body mass. This limitation hinders the study of juvenile small-bodied endangered species,...
Understanding the critical thresholds of dissolved oxygen (O 2) that trigger adaptive physiological responses in aquatic organisms is long hampered by a lack of robust, non-lethal or non-invasive methodologies. The isotope fractionation of triple O 2 isotopes (18 O/ 17 O/ 16 O) during respiration is linked to the amount of oxygen utilised, offering...
Due to the absence of relevant data on the species distribution and ploidy status of the Carassius species, we analysed samples from the river basins of Slovakia. We processed 252 individuals belonging to the genus Carassius originating from 60 localities (59 from the Danube River basins, and 1 from the Vistula River basin). Fin clips were collecte...
Although studies on fish cognition are increasing, consideration of how methodological details influence the ability to detect and measure performance is lagging. Here, in two separate experiments the authors compared latency to leave the start position, latency to make a decision, levels of participation and success rates (whether fish entered the...
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...
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...
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....
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...
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...
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...
Atlantic salmon (Salmo salar) 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 st...
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.
An important, b...
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...
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...
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...
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 limite...
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...
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...
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...
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...
Selection induced by human harvest can lead to different patterns of phenotypic change than selection induced by 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...
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...
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...
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...
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...
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...
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...
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...
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...
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...
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...
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...
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...
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...
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...
Parasitic species can affect host behaviour in various ways. Freshwater mussels of the superfamily U nionoidea 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, an...
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...