Trophic level
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The concentrations of hydrophobic organic compounds (HOCs) in aquatic biota are used for compliance, as well as time and spatial trend monitoring in the aqueous environment (European Union water framework directive, OSPAR). Because of trophic magnification in the food chain, the thermodynamic levels of HOCs, for example, polychlorinated biphenyl congeners, dichlorodiphenyltrichloroethane, and brominated diphenyl ether congeners, in higher trophic level (TL) organisms are expected to be strongly elevated above those in water. This work compares lipid-based concentrations at equilibrium with the water phase derived from aqueous passive sampling (CL⇌water) with the lipid-based concentrations in fillet and liver of fish (CL) at different TLs for three water bodies in the Czech Republic and Slovakia. The CL values of HOCs in fish were near CL⇌water, only after trophic magnification up to TL = 4. For fish at lower TL, CL progressively decreased relative to CL⇌water as KOW of HOCs increased above 106. The CL value decreasing toward the bottom of the food chain suggests nonequilibrium for primary producers (algae), which is in agreement with modeling passive HOC uptake by algae. Because trophic magnification and the resulting CL in fish exhibit large natural variability, CL⇌water is a viable alternative for monitoring HOCs using fish, showing a twofold lower confidence range and requiring less samples.
- MeSH
- chemické látky znečišťující vodu * analýza MeSH
- monitorování životního prostředí * MeSH
- potravní řetězec MeSH
- ryby MeSH
- sladká voda MeSH
- voda MeSH
- zvířata MeSH
- Check Tag
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Geografické názvy
- Česká republika MeSH
- Slovenská republika MeSH
Among spiders, taxonomically the most diversified group of terrestrial predators, only a few species are stenophagous and feed on ants. The levels of stenophagy and ant-specialisation vary among such species. To investigate whether stenophagy is only a result of a local specialisation both fundamental and realised trophic niches need to be estimated. Here we investigated trophic niches in three closely-related spider species from the family Gnaphosidae (Callilepis nocturna, C. schuszteri, Nomisia exornata) with different levels of myrmecophagy. Acceptance experiments were used to estimate fundamental trophic niches and molecular methods to estimate realised trophic niches. For the latter two PCR primer sets were used as these can affect the niche breadth estimates. The general invertebrate ZBJ primers were not appropriate for detecting ant DNA as they revealed very few prey types, therefore ant-specific primers were used. The cut-off threshold for erroneous MOTUs was identified as 0.005% of the total number of valid sequences, at individual predator level it was 0.05%. The fundamental trophic niche of Callilepis species included mainly ants, while that of N. exornata included many different prey types. The realised trophic niche in Callilepis species was similar to its fundamental niche but in N. exornata the fundamental niche was wider than realised niche. The results show that Callilepis species are ant-eating (specialised) stenophagous predators, catching mainly Formicinae ants, while N. exornata is an ant-eating euryphagous predator catching mainly Myrmicinae ants.
OBJECTIVES: The aim of this study was to clarify the influence of three different sizes of platinum nanoparticles on aquatic ecosystem and assess the toxic effect in term of particle size. Tests were conducted on organisms representing all trophic levels of the aquatic ecosystem, namely producers (duckweed Lemna minor), consumers (water fleas Daphnia magna) and decomposers (bacteria Vibrio fischeri). DESIGN: Experiments were carried out methodologically in accordance with the following standards: OECD 221 guideline (Lemna sp. Growth Inhibition test), OECD 202 guideline (Inhibition of the mobility of Daphnia magna) and ISO 11348-2 (Inhibitory effect of platinum nanoparticles on the light emission of Vibrio fischeri). RESULTS: The most toxic have been the smallest sized platinum nanoparticles for all tested organisms. The highest toxicity of all tested samples (Pt1, Pt2, Pt3) was observed in bacteria (30 ́EC50 = 135.47; 167.94; 254.64 μg.L-1), respectively. The lowest toxicity was recorded for Daphnia (48hEC50 = 405.74; 413.24; 514.07 μg.L-1), respectively. CONCLUSION: The ecotoxicity of platinum nanoparticles varies considerably according to the test organisms and particle size.
Generalist species commonly have a fundamental role in ecosystems as they can integrate spatially distinct habitats and food-web compartments, as well as control the composition, abundance and behavior of organisms at different trophic levels. Generalist populations typically consist of specialized individuals, but the potential for and hence degree of individual niche variation can be largely determined by habitat complexity. We compared individual niche variation within three generalist fishes between two comparable lakes in the Czech Republic differing in macrophyte cover, i.e. macrophyte-rich Milada and macrophyte-poor Most. We tested the hypothesis that large individual niche variation among generalist fishes is facilitated by the presence of macrophytes, which provides niches and predation shelter for fish and their prey items. Based on results from stable nitrogen (δ15N) and carbon (δ13C) isotopic mixing models, perch (Perca fluviatilis L.) and rudd (Scardinius erythrophthalmus (L.)) showed larger individual variation (i.e., variance) in trophic position in Milada as compared to Most, whereas no significant between-lake differences were observed for roach (Rutilus rutilus (L.)). Contrary to our hypothesis, all the three species showed significantly lower individual variation in the relative reliance on littoral food resources in Milada than in Most. Rudd relied significantly more whereas perch and roach relied less on littoral food resources in Milada than in Most, likely due to prevalent herbivory by rudd and prevalent zooplanktivory by perch and roach in the macrophyte-rich Milada as compared to macrophyte-poor Most. Our study demonstrates how the succession of macrophyte vegetation, via its effects on the physical and biological complexity of the littoral zone and on the availability of small prey fish and zooplankton, can strongly influence individual niche variation among generalist fishes with different ontogenetic trajectories, and hence the overall food-web structures in lake ecosystems.
- MeSH
- biodiverzita MeSH
- ekosystém * MeSH
- izotopy dusíku analýza MeSH
- potravní řetězec MeSH
- rostliny * MeSH
- ryby * MeSH
- zvířata MeSH
- Check Tag
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
Hereditary cerebellar degenerations are severe and complex diseases for which there is currently no effective causal treatment. A hopeful method could be the support of plasticity or neurotransplantation. However, there are still many unknown aspects which could influence the outcome of treatment. As neurotrophic factors are essential in neuroplasticity and neuronal integration, potential abnormalities in their levels could be involved in the pathogenesis of the disease and would possibly explain the unsuitability of diseased cerebellum for the graft integration. The aim of this study was to identify and compare basal levels of trophic factors BDNF and GDNF in the cerebellum in two mouse models of cerebellar degeneration - Lurcher and pcd. Basal levels of BDNF in the cerebellum have been shown to be lower in both mutant models than in healthy controls. However, the GDNF levels were surprisingly increased in the cerebella of Lurcher mutant mice compared to both wild type and pcd mice. In addition, a different distribution of GFAP-positive cells in the cerebellum was revealed in Lurcher mice. These differences suggest that the niche of the Lurcher mutant cerebellum is changed. The question, however, remains how these changes are related to the neurodegenerative process and how they could influence potential compensatory mechanisms, plasticity and response to therapeutic interventions.
- MeSH
- biologické markery metabolismus MeSH
- mozeček chemie metabolismus MeSH
- mozkový neurotrofický faktor genetika metabolismus MeSH
- mutace fyziologie MeSH
- myši - mutanty neurologické MeSH
- myši inbrední CBA MeSH
- myši transgenní MeSH
- myši MeSH
- neurodegenerativní nemoci genetika metabolismus MeSH
- růstový faktor GDNF genetika metabolismus MeSH
- zvířata MeSH
- Check Tag
- myši MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
Global change affects individual phenotypes and biotic interactions, which can have cascading effects up to the ecosystem level. However, the role of environmentally induced phenotypic plasticity in species interactions is poorly understood, leaving a substantial gap in our knowledge of the impacts of global change on ecosystems. Using a cladoceran-dragonfly system, we experimentally investigated the effects of thermal acclimation, acute temperature change and enrichment on predator functional response and metabolic rate. Using our experimental data, we next parameterized a population dynamics model to determine the consequences of these effects on trophic interaction strength and food-chain stability. We found that (1) predation and metabolic rates of the dragonfly larvae increase with acute warming, (2) warm-acclimated larvae have a higher maximum predation rate than cold-acclimated ones, and (3) long-term interaction strength increases with enrichment but decreases with both acclimation and acute temperatures. Overall, our experimental results show that thermal acclimation can buffer negative impacts of environmental change on predators and increase food-web stability and persistence. We conclude that the effect of acclimation and, more generally, phenotypic plasticity on trophic interactions should not be overlooked if we aim to understand the effects of climate change and enrichment on species interaction strength and food-web stability.
- MeSH
- aklimatizace MeSH
- bazální metabolismus * MeSH
- biologické modely MeSH
- Daphnia fyziologie MeSH
- klimatické změny MeSH
- larva růst a vývoj fyziologie MeSH
- nízká teplota MeSH
- populační dynamika MeSH
- potravní řetězec * MeSH
- predátorské chování * MeSH
- vážky růst a vývoj fyziologie MeSH
- vysoká teplota MeSH
- zvířata MeSH
- Check Tag
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
Most of earth's biodiversity is comprised of interactions among species, yet it is unclear what causes variation in interaction diversity across space and time. We define interaction diversity as the richness and relative abundance of interactions linking species together at scales from localized, measurable webs to entire ecosystems. Large-scale patterns suggest that two basic components of interaction diversity differ substantially and predictably between different ecosystems: overall taxonomic diversity and host specificity of consumers. Understanding how these factors influence interaction diversity, and quantifying the causes and effects of variation in interaction diversity are important goals for community ecology. While previous studies have examined the effects of sampling bias and consumer specialization on determining patterns of ecological networks, these studies were restricted to two trophic levels and did not incorporate realistic variation in species diversity and consumer diet breadth. Here, we developed a food web model to generate tri-trophic ecological networks, and evaluated specific hypotheses about how the diversity of trophic interactions and species diversity are related under different scenarios of species richness, taxonomic abundance, and consumer diet breadth. We investigated the accumulation of species and interactions and found that interactions accumulate more quickly; thus, the accumulation of novel interactions may require less sampling effort than sampling species in order to get reliable estimates of either type of diversity. Mean consumer diet breadth influenced the correlation between species and interaction diversity significantly more than variation in both species richness and taxonomic abundance. However, this effect of diet breadth on interaction diversity is conditional on the number of observed interactions included in the models. The results presented here will help develop realistic predictions of the relationships between consumer diet breadth, interaction diversity, and species diversity within multi-trophic communities, which is critical for the conservation of biodiversity in this period of accelerated global change.
Balneotherapy is a modern and perspective method of treatment of some skin diseases. Enhanced proliferation of epidermal cells in psoriatic plaques can be influenced by many different procedures. The objective of the present work was to evaluate in vivo the effect of hydrogen sulphide water, which is used for balneotherapeutic procedures in 10 patients with chronic stationary psoriasis vulgaris. The authors investigated the receptor characteristics at keratinocytic binding sites in psoriatic plaques before the balneotherapeutic application of hydrogen sulphide water and after its termination. They found that this method of balneotherapy reduces the pathologically enlarged number of receptors for the epidermal growth factor on keratinocytes to a level which corresponds to findings in normal subjects. The described experiments can contribute to the explanation of favourable therapeutic effects of hydrogen sulphide water on reduced hyperproliferation of keratinocytes in the psoriatic epidermis and thus have a favourable effect on psoriatic changes.
The life cycle of Hedruris spinigera Baylis, 1931 (Nematoda: Hedruridae) is determined here with the first formal identification of the parasite's intermediate host: the crustacean amphipod Paracorophium excavatum Thomson. Adult H. spinigera are redescribed from specimens collected from the stomach of fishes, Retropinna retropinna (Richardson) and Aldrichettaforsteri (Valenciennes), from Lake Waihola, New Zealand. Immature adults of the parasite collected from intermediate hosts (P. excavatum) are also described for the first time. The prevalence, abundance and intensity of infection of H. spinigera in several fish species are quantified along with the occurrence of P. excavatum, the parasite's intermediate host, in fish stomach contents. Although H. spinigera's transmission mode (trophic transmission) and fish diet potentially expose all fish species to infection, some level of host specificity must exist as parasite prevalence, abundance and intensity of infection vary greatly between potential definitive host species. We suggest here that the anatomy of the fish digestive tract and especially that of the stomach plays an important role in host suitability for H. spinigera. While P. excavatum is the only intermediate host in Lake Waihola, H. spinigera was found in six different fish species: Aldrichetta forsteri, Galaxias maculatus (Jenyns), Retropinna retropinna, Rhombosolea retiaria Hutton, Perca fluviatilis Linnaeus and Salmo trutta Linnaeus; although typical hedrurid attachment and mating positions were observed only in R. retropinna and A. forsteri. The limited distribution of H. spinigera is most likely due to that of its different host species (intermediate and definitive), all inhabitants of coastal fresh and brackish waters.
- MeSH
- Amphipoda parazitologie MeSH
- financování organizované MeSH
- hlístice anatomie a histologie fyziologie MeSH
- interakce hostitele a parazita MeSH
- nemoci ryb epidemiologie parazitologie MeSH
- potravní řetězec MeSH
- prevalence MeSH
- ryby parazitologie MeSH
- zvířata MeSH
- Check Tag
- zvířata MeSH
- Geografické názvy
- Nový Zéland MeSH
The author of the article presents a case study based on her own experience with using radiation for treatment of poorly healing wounds and trophic defects.
- MeSH
- dekubity ošetřování terapie MeSH
- hojení ran MeSH
- laserová terapie s nízkou intenzitou světla metody ošetřování využití MeSH
- lidé středního věku MeSH
- lidé MeSH
- ošetřovatelská péče metody MeSH
- výsledek terapie MeSH
- Check Tag
- lidé středního věku MeSH
- lidé MeSH
- mužské pohlaví MeSH
- Publikační typ
- kazuistiky MeSH
