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1.
J Zoo Wildl Med ; 51(4): 1012-1016, 2021 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-33480583

RESUMO

Reference intervals of intraocular pressure (IOP) are poorly described in piscine species as the factors that may influence it. Rebound tonometry was used to measure IOP in 28 adult brook trout (Salvelinus fontinalis) anesthetized in a buffered solution of 60 mg/L tricaine methanesulfonate (n = 16) or restrained with electronarcosis (n = 12) at 16 mA. There was no significant effect of the eye side, sex, fish origin, and body weight, but IOP values were significantly higher with electronarcosis (mean ± SD: 16.4 ± 5.0 mm Hg) than with immersion anesthesia (10.8 ± 3.3 mm Hg; P = 0.0017). The same restraint method should be used for comparison with previously published IOP values or when evaluating individual variations over time.


Assuntos
Aminobenzoatos/farmacologia , Eletronarcose/veterinária , Pressão Intraocular/fisiologia , Tonometria Ocular/veterinária , Truta/fisiologia , Anestésicos/farmacologia , Animais , Feminino , Pressão Intraocular/efeitos dos fármacos , Masculino , Tonometria Ocular/métodos
2.
Chemosphere ; 254: 126882, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32957289

RESUMO

Methamphetamine, mainly consumed as an illicit drug, is a potent addictive psychostimulant that has been detected in surface water at concentrations ranging from nanograms to micrograms per litre, especially in Middle and East Europe. The aim of this study was to expose brown trout (Salmo trutta fario) to environmental (1 µg L-1) and higher (50 µg L-1) concentrations of methamphetamine for 35 days with a four-day depuration phase to assess the possible negative effects on fish health. Degenerative liver and heart alterations, similar to those described in mammals, were observed at both concentrations, although at different intensities. Apoptotic changes in hepatocytes, revealed by activated caspase-3, were found in exposed fish. The parent compound and a metabolite (amphetamine) were detected in fish tissues in both concentration groups, in the order of kidney > liver > brain > muscle > plasma. Bioconcentration factors ranged from 0.13 to 80. A therapeutic plasma concentration was reached for both compounds in the high-concentration treatment. This study indicates that chronic environmental concentrations of methamphetamine can lead to health issues in aquatic organisms.


Assuntos
Metanfetamina/toxicidade , Truta/fisiologia , Poluentes Químicos da Água/toxicidade , Animais , Europa (Continente) , Rim/patologia , Fígado/metabolismo , Truta/metabolismo
3.
PLoS One ; 15(9): e0237716, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32886676

RESUMO

Bull trout (Salvelinus confluentus) are challenging to detect as a result of the species cryptic behavior and coloration, relatively low densities in complex habitats, and affinity for cold, high clarity, low conductivity waters. Bull trout are also closely associated with the stream bed, frequently conceal in substrate, and this concealment behavior is poorly understood. Consequently, population assessments are problematic and biologists and managers often lack quantitative information to accurately describe bull trout distributions, estimate abundance, and assess status and trends; particularly for stream-dwelling populations. During controlled laboratory trials, we recorded concealment, resting, and swimming behavior of juvenile wild bull trout in response to: (1) constant and fluctuating water temperature, (2) presence or absence of light, and (3) substrate size. Light level had the strongest influence on wild fish concealment and more fish concealed as light levels increased from darkness to daylight. Wild fish were 14.5 times less likely to conceal in constant darkness and 4.1 times more likely to conceal in 12 h light x 12 h darkness compared to constant light. Wild fish were 6.2 times less likely to conceal in small (26-51 mm) substrate compared to larger (52-102 mm) substrate. As water temperature increased, fewer wild fish concealed. Knowledge of wild bull trout concealment will improve field sampling protocols and increase detection efficiencies. These data also enhance knowledge of bull trout niche requirements which illuminates ecological differences among species and informs conservation and restoration efforts.


Assuntos
Truta/fisiologia , Distribuição Animal , Animais , Comportamento Animal , Fotoperíodo , Rios/química , Natação , Temperatura
4.
Environ Pollut ; 260: 113925, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-32369894

RESUMO

Copper is known to interfere with fish olfaction. Although the chemosensory detection and olfactory toxicity of copper ions (Cu2+) has been heavily studied in fish, the olfactory-driven detection of copper nanoparticles (CuNPs)-a rapidly emerging contaminant to aquatic systems-remains largely unknown. This study aimed to investigate the olfactory response of rainbow trout to equitoxic concentrations of CuNPs or Cu2+ using electro-olfactography (EOG, a neurophysiological technique) and olfactory-mediated behavioural assay. In the first experiment, the concentration of contaminants known to impair olfaction by 20% over 24 h (EOG-based 24-h IC20s of 220 and 3.5 µg/L for CuNPs and Cu2+, respectively) were tested as olfactory stimuli using both neurophysiological and behavioural assays. In the second experiment, to determine whether the presence of CuNPs or Cu2+ can affect the ability of fish to perceive a social cue (taurocholic acid (TCA)), fish were acutely exposed to one form of Cu-contaminants (approximately 15 min). Following exposure, olfactory sensitivity was measured by EOG and olfactory-mediated behaviour within a choice maze was recorded in the presence of TCA. Results of neurophysiological and behavioural experiments demonstrate that rainbow trout can detect and avoid the IC20 of CuNPs. The IC20 of Cu2+ was below the olfactory detection threshold of rainbow trout, as such, fish did not avoid Cu2+. The high sensitivity of behavioural endpoints revealed a lack of aversion response to TCA in CuNP-exposed fish, despite this change not being present utilizing EOG. The reduced response to TCA during the brief exposure to CuNPs may be a result of either olfactory fatigue or blockage of olfactory sensory neurons (OSNs) by CuNPs. The observed behavioural interference caused by CuNP exposure may indicate that CuNPs have the ability to interfere with other behaviours potentially affecting fitness and survival. Our findings also revealed the differential response of OSNs to CuNPs and Cu2+.


Assuntos
Cobre/toxicidade , Nanopartículas/toxicidade , Oncorhynchus mykiss , Truta/fisiologia , Poluentes Químicos da Água/toxicidade , Animais , Íons
5.
Proc Natl Acad Sci U S A ; 117(19): 10585-10592, 2020 05 12.
Artigo em Inglês | MEDLINE | ID: mdl-32341168

RESUMO

The anterior body of many fishes is shaped like an airfoil turned on its side. With an oscillating angle to the swimming direction, such an airfoil experiences negative pressure due to both its shape and pitching movements. This negative pressure acts as thrust forces on the anterior body. Here, we apply a high-resolution, pressure-based approach to describe how two fishes, bluegill sunfish (Lepomis macrochirus Rafinesque) and brook trout (Salvelinus fontinalis Mitchill), swimming in the carangiform mode, the most common fish swimming mode, generate thrust on their anterior bodies using leading-edge suction mechanics, much like an airfoil. These mechanics contrast with those previously reported in lampreys-anguilliform swimmers-which produce thrust with negative pressure but do so through undulatory mechanics. The thrust produced on the anterior bodies of these carangiform swimmers through negative pressure comprises 28% of the total thrust produced over the body and caudal fin, substantially decreasing the net drag on the anterior body. On the posterior region, subtle differences in body shape and kinematics allow trout to produce more thrust than bluegill, suggesting that they may swim more effectively. Despite the large phylogenetic distance between these species, and differences near the tail, the pressure profiles around the anterior body are similar. We suggest that such airfoil-like mechanics are highly efficient, because they require very little movement and therefore relatively little active muscular energy, and may be used by a wide range of fishes since many species have appropriately shaped bodies.


Assuntos
Fenômenos Biomecânicos/fisiologia , Peixes/fisiologia , Natação/fisiologia , Animais , Peixes/anatomia & histologia , Movimento , Perciformes/fisiologia , Fenômenos Físicos , Truta/fisiologia
6.
Proc Biol Sci ; 287(1925): 20200388, 2020 04 29.
Artigo em Inglês | MEDLINE | ID: mdl-32315591

RESUMO

Genetic variation in defence against parasite infections is fundamental for host-parasite evolution. The overall level of defence of a host individual or population includes mechanisms that reduce parasite exposure (avoidance), establishment (resistance) or pathogenicity (tolerance). However, how these traits operate and evolve in concert is not well understood. Here, we investigated genetic variation in and associations between avoidance, resistance and tolerance in a natural host-parasite system. Replicated populations of Atlantic salmon (Salmo salar) and sea trout (an anadromous form of brown trout, Salmo trutta) were raised under common garden conditions and infected with the eye fluke Diplostomum pseudospathaceum. We demonstrate significant genetic variation in the defence traits across host populations and negative associations between the traits, with the most resistant populations showing the weakest avoidance and the lowest infection tolerance. These results are suggestive of trade-offs between different components of defence and possibly underlie the genetic variation in defence traits observed in the wild. Because the three defence mechanisms affect host-parasite evolution in profoundly different ways, we emphasize the importance of studying these traits in concert.


Assuntos
Doenças dos Peixes/parasitologia , Interações Hospedeiro-Parasita , Animais , Parasitos , Salmo salar/parasitologia , Salmo salar/fisiologia , Trematódeos , Truta/parasitologia , Truta/fisiologia
7.
J Fish Biol ; 96(6): 1489-1494, 2020 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-32128819

RESUMO

Anadromy was documented in 16 lake trout, Salvelinus namaycush, from Canada's central Arctic using capture data and otolith microchemistry. For the first time, estuarine/marine habitat use was described for five individuals using acoustic telemetry. Age-at-first-migration to sea was variable (10-39 years) among individuals and most S. namaycush undertook multiple anadromous migrations within their lifetime. Telemetry data suggested that S. namaycush do not travel far into marine habitats and prefer surface waters (<2 m). These results further our collective understanding of the marine ecology of Arctic S. namaycush.


Assuntos
Ecossistema , Truta/fisiologia , Animais , Regiões Árticas , Canadá , Membrana dos Otólitos/química
8.
Sci Rep ; 10(1): 1929, 2020 02 06.
Artigo em Inglês | MEDLINE | ID: mdl-32029847

RESUMO

Domestication involves adapting animals to the human-controlled environment. Genetic changes occurring during the domestication process may manifest themselves in phenotypes that render domesticated animals maladaptive for life in the wild. Domesticated Atlantic salmon frequently interbreed with wild conspecifics, and their offspring display reduced survival in the wild. However, the mechanism(s) contributing to their lower survival in the wild remains a subject of conjecture. Here, we document higher susceptibility to predation by brown trout in fast-growing domesticated salmon, as compared to their slow-growing wild conspecifics, demonstrating that directional selection for increased growth comes at a cost of decreased survival when under the risk of predation, as predicted by the growth/predation risk trade-off. Despite earlier documentation of altered risk-taking behavior, this study demonstrates for the first time that domestication of Atlantic salmon has lead to increased predation susceptibility, and that this consitutes a mechanism underpinning the observed survial differences in the wild.


Assuntos
Animais Domésticos/fisiologia , Domesticação , Salmo salar/fisiologia , Animais , Animais Domésticos/crescimento & desenvolvimento , Fenótipo , Salmo salar/crescimento & desenvolvimento , Truta/crescimento & desenvolvimento , Truta/fisiologia
9.
Sci Rep ; 10(1): 3529, 2020 02 26.
Artigo em Inglês | MEDLINE | ID: mdl-32103141

RESUMO

Anadromous salmon and sea trout smolts face challenging migrations from freshwater to the marine environment characterised by high mortality. Therefore, the timing of smolt migration is likely to be critical for survival. Time-series comparing migration of Atlantic salmon and sea trout smolts in the same river, and their response to the same environmental cues, are scarce. Here, we analysed migration timing of ~41 000 Atlantic salmon and sea trout smolts over a 19-year period from the river Guddalselva, western Norway. Trout displayed a longer migration window in earlier years, which decreased over time to become more similar to the salmon migration window. On average, salmon migrated out of the river earlier than trout. Migration of both species was significantly influenced by river water temperature and water discharge, but their relative influence varied across the years. On average, body-length of smolts of both species overlapped, however, size differences were observed within the migration period and among the years. We conclude that salmon and trout smolts in this river are highly synchronised and migrate in response to the same range of linked environmental cues.


Assuntos
Migração Animal/fisiologia , Rios , Salmo salar/fisiologia , Truta/fisiologia , Animais , Noruega , Temperatura
10.
J Fish Biol ; 96(3): 681-692, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31970772

RESUMO

Life history strategies and potential marine niche use of Arctic charr Salvelinus alpinus (n = 237, 84-652 mm, total body length, LT ) were determined during the ice-free season (2012) at three different watercourses in south-western Greenland. All Arctic charr were collected from freshwater habitats. Based on stable isotopes of δ34 S, the Arctic charr were categorized as either marine- or freshwater-dependent feeders. The use of time-integrated trophic tracers (stable isotopes of δ13 C, δ15 N, δ34 S) suggested that several trophic groups of Arctic charr operate alongside within each fjord system. The groups suggested were one group that specialized in the marine habitat, in addition to two freshwater resident morphs (small-sized resident and/or large-growing cannibalistic individuals). Stomach contents consisted entirely of freshwater and terrestrial prey (i.e., insects), indicating that marine-dependent feeders also fed in freshwater habitats after return from their marine migration. Growth and maturity patterns further supported variable life history strategies within each watercourse. The life history strategy patterns and marine trophic niche use were consistent across the watercourses along several hundred kilometres of coastline. This study represents the first ecological baseline for partially anadromous populations of Greenland Arctic charr.


Assuntos
Dieta , Ecossistema , Truta/fisiologia , Animais , Organismos Aquáticos/metabolismo , Canibalismo , Água Doce , Conteúdo Gastrointestinal , Groenlândia , Estado Nutricional , Estações do Ano , Isótopos de Enxofre/análise , Truta/crescimento & desenvolvimento
11.
J Fish Biol ; 96(3): 693-699, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31985071

RESUMO

Cryptic female choice is often mediated chemically in external fertilizers by ovarian fluid (OF), which can change sperm swimming performance and bias paternity under sperm competition. Assessing cryptic female choice is hindered by the necessity of using fresh gametes and the short time window available to obtain diverse samples from wild animals. Using split-ejaculate experimental designs and samples from lake trout, brown trout and Atlantic salmon, we evaluated whether freezing OF alters the way in which it modifies sperm swimming. Sperm had improved swimming performance in the presence of OF over plain water, and the effect did not depend on whether the OF had previously been frozen. Freezing OF does not seem to alter the way it influences sperm. This allows the researcher to create a 'spice rack' of OF samples that can be used in studies on cryptic female choice, and opens up the possibility to compare animals mating under large spatial and temporal variability.


Assuntos
Peixes/fisiologia , Congelamento , Ovário/fisiologia , Motilidade Espermática/fisiologia , Animais , Feminino , Fertilização , Masculino , Ovário/química , Reprodução , Projetos de Pesquisa/normas , Salmo salar/fisiologia , Truta/fisiologia
12.
Chemosphere ; 239: 124797, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31521930

RESUMO

F2-isoprostanes (F2-isoPs) are a reliable biomarker class for oxidative stress in vivo in animals. These compounds are traditionally measured in matrices like liver and plasma, however social and environmental pressures warrant the development of non-lethal and non-invasive methods to assess animal health. Therefore, this study aimed to develop a high-performance liquid chromatography tandem mass spectrometry (HPLC-ESI-MS/MS) method to separate and detect F2-isoPs in fish mucus. The method was developed and validated for four native F2-isoP isomers using Northern pike mucus (Esox lucius). Linearity was observed between 5 and 1000 pg/µL. The limits of detection of the four F2-IsoP isomers ranged from 0.63 to 2.0 ng/g. Recoveries ranged from 78 to 95%, and matrix effects were small (<10%). The between-day and within-day repeatability for all target analytes was lower than 20% RSD. Endogenous F2-isoPs were measured in the pike mucus (5.3-28.8 ng/g). A preliminary study of baseline F2-isoP concentrations in lake trout (Salvelinus namaycush) captured from five lakes at the IISD-Experimental Lakes Area in Northwestern Ontario, Canada, was also conducted to test the interspecies applicability of the method. Endogenous F2-isoPs were quantified in lake trout (6.3-132 ng/g). Lake trout samples displayed large variability within and between the different lakes, which suggests sampling methods may require adjustment for this species. This work developed a sensitive analytical method for measuring F2-isoPs in fish mucus, however several further studies are required to determine its ability to accurately measure oxidative stress in fish species.


Assuntos
Biomarcadores/análise , F2-Isoprostanos/análise , Peixes/fisiologia , Muco/química , Estresse Oxidativo , Animais , Monitoramento Biológico/métodos , Cromatografia Líquida de Alta Pressão , Feminino , Lagos , Fígado/química , Masculino , Muco/metabolismo , Ontário , Reprodutibilidade dos Testes , Espectrometria de Massas por Ionização por Electrospray , Espectrometria de Massas em Tandem , Truta/fisiologia
13.
Chemosphere ; 239: 124608, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31499312

RESUMO

Freshwater systems are faced with a myriad of stressors including geomorphological alterations, nutrient overloading and pollution. Previous studies in marine fish showed polyaromatic hydrocarbons (PAHs) to be cardiotoxic. However, the cardiotoxicity of anthropogenic pollutants in freshwater fishes is unclear and has not been examined across multiple levels of cardiac organization. Here we investigated the effect of phenanthrene (Phe), a pervasive anthropogenic pollutant on a sentinel freshwater species, the brown trout (Salmo trutta). We first examined the electrical activity of the whole heart and found prolongation (∼8.6%) of the QT interval (time between ventricular depolarization and repolarization) of the electrocardiogram (ECG) and prolongation (∼13.2%) of the monophasic action potential duration (MAPD) following ascending doses of Phe. At the tissue level, Phe significantly reduced trabecular force generation by ∼24% at concentration 15 µM and above, suggesting Phe reduces cellular calcium cycling. This finding was supported by florescent microscopy showing a reduction (∼39%) in the intracellular calcium transient amplitude following Phe exposure in isolated brown trout ventricular myocytes. Single-cell electrophysiology was used to reveal the mechanism underlying contractile and electrical dysfunction following Phe exposure. A Phe-dependent reduction (∼38%) in the L-type Ca2+ current accounts, at least in part, for the lowered Ca2+ transient and force production. Prolongation of the MAPD and QT interval was explained by a reduction (∼70%) in the repolarising delayed rectifier K+ current following Phe exposure. Taken together, our study shows a direct impact of Phe across multiple levels of cardiac organization in a key freshwater salmonid.


Assuntos
Miócitos Cardíacos/efeitos dos fármacos , Miócitos Cardíacos/patologia , Fenantrenos/toxicidade , Truta/fisiologia , Poluentes Químicos da Água/toxicidade , Animais , Cardiotoxicidade , Eletrocardiografia , Água Doce/química
14.
Environ Sci Pollut Res Int ; 27(6): 6352-6361, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31873896

RESUMO

Endemic fish species of Armenian ichthyofauna-Sevan trout (Salmo ischchan Kessler, 1877)-is registered in the Red Book of Animals of the Republic of Armenia as "Critically Endangered" (corresponds to IUCN category: CR A2cd). Its natural reproduction hardly occurs as a result of numerous problems related to the use and management of water and bio-resources in the Lake Sevan drainage basin. Masrik River is formerly known as a spawning river for two ecological races of the Sevan trout, but there is no up-to-date and in-depth studies of its potential to support natural reproduction. Thus, a set of spawning criteria was arranged as matrix and state of Masrik River as spawning area for the Sevan trout was assessed. The results showed that the potential of different parts of Masrik River to support natural reproduction of Sevan trout varied from quite appropriate to inappropriate. The main limiting factors revealed were water temperature, velocity and substrate conditions.


Assuntos
Monitoramento Ambiental , Rios , Truta/fisiologia , Animais , Armênia , Lagos , Reprodução , Alimentos Marinhos
15.
BMC Evol Biol ; 19(1): 227, 2019 12 16.
Artigo em Inglês | MEDLINE | ID: mdl-31842751

RESUMO

BACKGROUND: The presence of a novel pollutant can induce rapid evolution if there is additive genetic variance for the tolerance to the stressor. Continuous selection over some generations can then reduce the toxicity of the pollutant but also deplete the additive genetic variance for the tolerance and thereby slow down adaptation. One common pollutant that has been ecologically relevant for some time is 17alpha-ethynylestradiol (EE2), a synthetic compound of oral contraceptives since their market launch in the 1960s. EE2 is typically found in higher concentrations in rivers than in lakes. Recent experimental work revealed significant genetic variance for the tolerance to EE2 in two lake-spawning salmonid species but no such variance in river-spawning brown trout. We used another river-spawning salmonid, the European grayling Thymallus thymallus, to study the toxicity of an ecologically relevant concentration of EE2. We also used a full-factorial in vitro breeding design and singly rearing of 1555 embryos and larvae of 40 sib groups to test whether there is additive genetic variance for the tolerance to this pollutant. RESULTS: We found that exposure to EE2 reduced larval growth after hatching, but contrary to what has been found in the other salmonids, there were no significant effects of EE2 on embryo growth and survival. We found additive genetic variance for embryo viability, i.e. heritability for fitness. However, there was no significant additive variance for the tolerance to EE2. CONCLUSIONS: Our findings support the hypothesis that continuous selection has reduced the toxicity of EE2 and depleted genetic variance for tolerance to this synthetic stressor.


Assuntos
Etinilestradiol/toxicidade , Salmonidae/fisiologia , Poluentes Químicos da Água/toxicidade , Animais , Cruzamento , Rios/química , Truta/fisiologia
16.
Proc Natl Acad Sci U S A ; 116(47): 23600-23608, 2019 11 19.
Artigo em Inglês | MEDLINE | ID: mdl-31685632

RESUMO

To understand the impact reduced mercury (Hg) loading and invasive species have had on methylmercury bioaccumulation in predator fish of Lake Michigan, we reconstructed bioaccumulation trends from a fish archive (1978 to 2012). By measuring fish Hg stable isotope ratios, we related temporal changes in Hg concentrations to varying Hg sources. Additionally, dietary tracers were necessary to identify food web influences. Through combined Hg, C, and N stable isotopic analyses, we were able to differentiate between a shift in Hg sources to fish and periods when energetic transitions (from dreissenid mussels) led to the assimilation of contrasting Hg pools (2000 to present). In the late 1980s, lake trout δ202Hg increased (0.4‰) from regulatory reductions in regional Hg emissions. After 2000, C and N isotopes ratios revealed altered food web pathways, resulting in a benthic energetic shift and changes to Hg bioaccumulation. Continued increases in δ202Hg indicate fish are responding to several United States mercury emission mitigation strategies that were initiated circa 1990 and continued through the 2011 promulgation of the Mercury and Air Toxics Standards rule. Unlike archives of sediments, this fish archive tracks Hg sources susceptible to bioaccumulation in Great Lakes fisheries. Analysis reveals that trends in fish Hg concentrations can be substantially affected by shifts in trophic structure and dietary preferences initiated by invasive species in the Great Lakes. This does not diminish the benefits of declining emissions over this period, as fish Hg concentrations would have been higher without these actions.


Assuntos
Cadeia Alimentar , Compostos de Metilmercúrio/análise , Truta/metabolismo , Poluentes Químicos da Água/análise , Poluentes Atmosféricos/análise , Poluição do Ar/legislação & jurisprudência , Anfípodes/química , Animais , Dieta , Dreissena/química , Política Ambiental , Água Doce/química , Sedimentos Geológicos/química , Espécies Introduzidas , Lagos , Isótopos de Mercúrio/análise , Michigan , Comportamento Predatório , Fatores de Tempo , Truta/fisiologia
17.
Proc Biol Sci ; 286(1913): 20191992, 2019 10 23.
Artigo em Inglês | MEDLINE | ID: mdl-31640512

RESUMO

Ecological opportunity is considered a crucial factor for adaptive radiation. Here, we combine genetic, morphological and ecological data to assess species and ecomorphological diversity of Artic charr in six lakes of a catchment in southernmost Greenland, where only charr and stickleback occur. Because the diversity of habitats and resources increases with lake size, we predict a positive association between lake size and the extent of ecomorphological diversity. The largest lake of the catchment harbours the largest Arctic charr assemblage known today. It consists of six genetically differentiated species belonging to five ecomorphs (anadromous, littoral benthic, profundal dwarf, planktivorous, piscivorous), of which the latter comprises two ecomorphologically extremely similar species. Lakes of intermediate size contain two ecomorphologically and genetically distinct species. Small lakes harbour one genetically homogeneous, yet sometimes ecomorphologically variable population. Supporting our prediction, lake size is positively correlated with the extent of ecomorphological specialization towards profundal, pelagic and piscivorous lifestyle. Furthermore, assemblage-wide morphospace increases sharply when more than one genetic cluster is present. Our data suggest that ecological opportunity and speciation jointly determine phenotypic expansion in this charr radiation.


Assuntos
Distribuição Animal , Ecossistema , Truta/fisiologia , Animais , Lagos
18.
Sci Total Environ ; 693: 133648, 2019 Nov 25.
Artigo em Inglês | MEDLINE | ID: mdl-31634990

RESUMO

Streamflow is a main driver of fish population dynamics and is projected to decrease in much of the northern hemisphere, especially in the Mediterranean region, due to climate change. However, predictions of future climate effects on cold-water freshwater fish populations have typically focused only on the ecological consequences of increasing temperatures, overlooking the concurrent and interacting effects of climate-driven changes in streamflow regimes. Here, we present simulations that contrasted the consequences of changes in thermal regime alone versus the combined effects of changes in thermal regime and streamflow for resident trout populations in distinct river types with different sensitivities to climatic change (low-altitude main river vs. high-altitude headwaters). We additionally assessed the buffering effect of increased food production that may be linked to warming. We used an eco-genetic individual-based model that integrates the behavioural and physiological effects of extrinsic environmental drivers -temperature and flow- with intrinsic dynamics -density-dependence, phenotypic plasticity and evolutionary responses - across the entire trout life cycle, with Mediterranean brown trout Salmo trutta as the model species. Our simulations indicated that: (1) Hydrological change is a critical dimension of climate change for the persistence of trout populations, in that neither river type supported viable populations under strong rates of flow change, even under scenarios of increased food production. (2) Climate-change-related environmental change most affects the largest, oldest trout via increased metabolic costs and decreased energy inputs. In both river types, populations persisted under extreme warming alone but became dominated by younger, smaller fish. (3) Density-dependent, plastic and evolutionary changes in phenology and life-history traits provide trout populations with important resilience to warming, but strong concurrent shifts in streamflow could exceed the buffering conferred by such intrinsic dynamics.


Assuntos
Adaptação Psicológica , Mudança Climática , Temperatura , Truta/fisiologia , Adaptação Fisiológica , Animais , Água Doce , Hidrologia , Dinâmica Populacional , Rios , Movimentos da Água
19.
PLoS One ; 14(9): e0222182, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31491026

RESUMO

In this study we attempted to determine the effect of various feeding methods (bottom and surface feeding) used in the hatchery, on the survival and growth rates of hatchery-reared sea trout (Salmo trutta trutta L.) in the wild. Rearing was performed in two variants: a bottom-fed group (BFG) and a surface-fed group (SFG). At the end of the rearing time, we observed that BFG fish gathered at the bottom of tank, as opposed to SFG fish, which swam in the whole water column. After 4 weeks of rearing, the fish were released into two similar streams. After about 2 months the fish were captured and the foodbase of the streams were examined. 30 fish from each group have been randomly selected for stomach contents analysis. In the shallow stream the growth rates were better for the BFG fish than the SFG and also a significantly higher number of typical benthic taxa was found in stomachs of the BFG fish than the SFG fish. In the deeper stream more food was found in the stomachs of the SFG fish than in the BFG fish. The analyzed results showed that factors such as stream depth, current velocity, and turbulence can also affect the rearing success of juvenile salmonids in hatchery streams. Bottom feeding fish during rearing has a positive impact only on the fish in shallow watercourses, where there is no turbulence, and the food is not carried by the current drift or washed out from the bottom into the drift.


Assuntos
Meio Ambiente , Comportamento Alimentar , Pesqueiros , Truta/crescimento & desenvolvimento , Animais , Mucosa Gástrica/metabolismo , Análise de Sobrevida , Truta/metabolismo , Truta/fisiologia
20.
Biomolecules ; 9(9)2019 09 13.
Artigo em Inglês | MEDLINE | ID: mdl-31540333

RESUMO

Dietary carbon sources in headwater stream food webs are divided into allochthonous and autochthonous organic matters. We hypothesized that: 1) the dietary allochthonous contribution for fish in headwater stream food webs positively relate with canopy cover; and 2) essential fatty acids originate from autochthonous organic matter regardless of canopy covers, because essential fatty acids, such as 20:5ω3 and 22:6ω3, are normally absent in allochthonous organic matters. We investigated predatory fish Salvelinus leucomaenis stomach contents in four headwater stream systems, which are located in subarctic region in northern Japan. In addition, stable carbon and nitrogen isotope ratios, fatty acid profile, and stable carbon isotope ratios of essential fatty acids were analyzed. Bulk stable carbon analysis showed the major contribution of autochthonous sources to assimilated carbon in S. leucomaenis. Surface baits in the stomach had intermediate stable carbon isotope ratios between autochthonous and allochthonous organic matter, indicating aquatic carbon was partly assimilated by surface baits. Stable carbon isotope ratios of essential fatty acids showed a positive relationship between autochthonous sources and S. leucomaenis across four study sites. This study demonstrated that the main supplier of dietary carbon and essential fatty acids was autochthonous organic matter even in headwater stream ecosystems under high canopy cover.


Assuntos
Carbono/análise , Ácidos Graxos Essenciais/análise , Estômago/química , Truta/fisiologia , Animais , Ecossistema , Cadeia Alimentar , Japão , Comportamento Predatório
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