To cope with heterogeneous environments and resource distributions, filamentous fungi have evolved a spatially extensive growth enabling their hyphae to penetrate airŃwater interfaces and pass through air-filled pores. Such mycelia are also known to act as dispersal networks for the mobilisation of bacteria (ĺfungal highways̷) and connection of microbial microhabitats. Hitherto, however, nothing is known about the effect of mycelia-based dispersal on interactions between bacterial predators and their prey and concomitant effects on biomass formation. We here hypothesise that mycelia enable the contact between predators and their prey and shape a prey̷s population. We investigated the impact of predation by Bdellovibrio bacteriovorus 109J on the growth of its potential prey Pseudomonas fluorescens LP6a in the presence of mycelia. Our data give evidence that hyphae increase the accessibility of the prey to B. bacteriovorus 109J and, hence, allow for efficient foraging and shaping of prey populations not seen in the absence of mycelia. To test our hypothesis tailored microbial landscapes were used for better reduction of emerging properties in complex systems. Our data suggest that mycelia have substantial influence on preyŃpredator relationship and hereby may promote the structure of prey and predator populations and, hence, may be a determinant for biomass formation in heterogeneous environments. Quelle: https://www.nature.com/
Communities and food web structures of aquatic ecosystems can be strongly affected by the establishment of alien macroinvertebrate species. In many European waters, the invasion of the Ponto-Caspian amphipod Dikerogammarus villosus has led to displacement of other macroinvertebrates. Predation by D. villosus is often assumed to be the key driver of the displacement based on results of laboratory studies, but this has not been verified in the field. Here, we report our investigation of the relevance of D. villosus predation in the River Rhine system using both stable isotope analyses of d13C and d15N, and molecular analyses of D. villosus gut contents with group-specific primers aiming at macroinvertebrate prey taxa. Stable isotope analyses of D. villosus from ten sites showed mean d15N values comparable to those of primary consumers. Overall, only approximately 1% of all tested primer/gut content combinations revealed DNA of the respective taxa. Both indicate minor importance of predation by D. villosus as a driver of the observed macroinvertebrate displacement. Conceivably, competitive strength due to opportunistic feeding, indicated by different niche widths between and a strong intraspecific variation of d13C values of D. villosus within sites of our study, is much more important for its invasion success. Quelle: http://link.springer.com
Trace elements are chemical contaminants spread in the environment by anthropogenic activities and threaten wildlife and human health. Many studies have investigated this contamination in apex raptors as sentinel birds. However, there is limited data for long-term biomonitoring of multiple trace elements in raptors. In the present study, we measured the concentrations of 14 essential and non-essential trace elements in the livers of the common buzzard (Buteo buteo) collected in the United Kingdom from 2001 to 2019 and investigated whether concentrations have changed during this period. In addition, we estimated the importance of selected variables for modelling element accumulations in tissues. Except for cadmium, hepatic concentrations of harmful elements in most buzzards were lower than the biological significance level of each element. Hepatic concentrations of certain elements, including lead, cadmium, and arsenic, varied markedly seasonally within years. Their peak was in late winter and trough in late summer, except copper which showed an opposite seasonal pattern. In addition, lead in the liver consistently increased over time, whereas strontium showed a decreasing trend. Hepatic concentrations of cadmium, mercury, and chromium increased with age, whereas selenium and chromium were influenced by sex. Hepatic concentrations of arsenic and chromium also differed between different regions. Overall, our samples showed a low risk of harmful effects of most elements compared to the thresholds reported in the literature. Seasonal fluctuation was an important descriptor of exposure, which might be related to the diet of the buzzard, the ecology of their prey, and human activities such as the use of lead shot for hunting. However, elucidating reasons for these observed trends needs further examination, and biomonitoring studies exploring the effects of variables such as age, sex, and seasonality are required. © 2023 The Authors.
The increasing use of chemicals in the European Union (EU) has resulted in environmental emissions and wildlifeexposures. For approving a chemical within the EU, producers need to conduct an environmental risk assessment,which typically relies on data generated under laboratory conditions without considering the ecological andlandscape context. To address this gap and add information on emerging contaminants and chemical mixtures,we analysed 30 livers of white-tailed sea eagles (Haliaeetus albicilla) from northern Germany with highresolution-mass spectrometry coupled to liquid and gas chromatography for the identification of >2400 con-taminants. We then modelled the influence of trophic position (δ15N), habitat (δ13C) and landscape on chemicalresidues and screened for persistent, bioaccumulative and toxic (PBT) properties using an in silico model tounravel mismatches between predicted PBT properties and observed exposures. Despite having generally lowPBT scores, most detected contaminants were medicinal products with oxfendazole and salicylamide being mostfrequent. Chemicals of the Stockholm Convention such as 4,4â€2-DDE and PCBs were present in all samples belowtoxicity thresholds. Among PFAS, especially PFOS showed elevated concentrations compared to other studies. Incontrast, PFCA levels were low and increased with δ15N, which indicated an increase with preying on piscivorousspecies. Among plant protection products, spiroxamine and simazine were frequently detected with increasingconcentrations in agricultural landscapes. The in silico model has proven to be reliable for predicting PBTproperties for most chemicals. However, chemical exposures in apex predators are complex and do not solely relyon intrinsic chemical properties but also on other factors such as ecology and landscape. We therefore recom-mend that ecological contexts, mixture toxicities, and chemical monitoring data should be more frequentlyconsidered in regulatory risk assessments, e.g. in a weight of evidence approach, to trigger risk managementmeasures before adverse effects in individuals or populations start to manifest. © 2021 The Authors
Ein Lernangebot für Kinder. Der Habicht ist Vogel des Jahres 2015. Die Jungvögel sind braun gefärbt und haben keine Bänder, sondern Flecken auf der Bauchseite. "Hühnerhabicht" wurde er früher genannt, denn frei laufende Hühner waren für den schnellen Greifvogel eine leichte Beute. Der schlechte Ruf, den er bei den Hühnerhaltern hatte, ist ihm zum Verhängnis geworden: Viele machten Jagd auf den Vogel und fast wäre er ausgestorben. Heute dürfen Habichte nicht mehr gejagt werden und seine Bestände haben sich erholt. Versteckter Jäger Einen Habicht bei der Jagd zu entdecken, ist ziemliches Glück. Denn statt wie ein Bussard über offenem Gelände zu kreisen, wartet der Habicht auf seinem Ansitz im Baum darauf, dass ihm eine unvorsichtige Taube oder Krähe zu nahe kommt. Dann kann er blitzschnell starten. Bei der Verfolgung ziehen die Beutetiere meist den Kürzeren, denn Habichte sind sehr geschickt und umfliegen in rasender Geschwindigkeit jedes Hindernis. Vom Landei zum Städter Sein Revier ist der Wald oder offene Landschaften mit vielen alten Bäumen. Doch auch in Städten leben immer mehr Habichte. Berlin hat sogar deutschlandweit die größte Habichtdichte: 100 Brutpaare leben im Stadtgebiet! Das Stadtleben hat für die Vögel einige Vorteile: Krähen, Elstern und Tauben gibt es genug und in Stadtparks oder auf Friedhöfen stehen auch geeignete Bäume, in denen die Habichte ihren Horst bauen können. Außerdem haben die pfiffigen Vögel gemerkt, dass in der Stadt niemand Jagd auf sie macht.
Ein Lernangebot für Kinder. ('Foto: gemeinfrei) Wenn seine riesigen Tatzen den Waldboden berühren, machen sie kein Geräusch. Seine Streifen tarnen ihn so gut, dass er im Dickicht nicht zu sehen ist. Erst wenn er sich mit 300 Kilogramm Körpergewicht auf sein Beutetier stürzt, bemerkt dieses den Tiger. Doch dann ist es schon längst zu spät.
Ein Lernangebot für Kinder. Klein, aber oho! Die Spitzmaus gehört zu unseren kleinsten Säugetieren. Vom Kopf bis zur Schwanzspitze misst das Tierchen gerade einmal 8 Zentimeter. Aber die kleine Räuberin hat großen Appetit und kein Problem damit, auf Beutetiere loszugehen, die größer sind als sie selbst. Unterschätze niemals eine Spitzmaus!
Ein Lernangebot für Kinder. Die kleinste Giftschlange Europas Eine Wiesenotter. Ähnlich wie ein Wespenstich fühlt es sich an, wenn die Wiesenotter zubeißt. Sie ist die kleinste europäische Giftschlange und ihre Giftdrüsen deshalb auch ziemlich winzig. Ihre Beutetiere aber bringt sie damit mühelos zur Strecke. Auch wenn der Schlangenbiss für Menschen nicht gefährlich ist - für Eidechsen, Frösche, Heuschrecken und junge Mäuse ist er tödlich.
Ein Lernangebot für Kinder. Hast du schon mal vom "Neuntöter" gehört? Er ist keine Hauptfigur in einem Horrorfilm, sondern ein Singvogel, der auf Heiden und Wiesen zu Hause ist. Seinen gruseligen Namen trägt er, weil er gerne Vorräte anlegt: Wenn er seine Beutetiere getötet hat, spießt er sie auf Dornen auf und lagert sie dort so lange bis er sie frisst.
Up to now our knowledge of water mite diet has been fragmentary. It is derived from observations in the field and laboratory or from a few selective laboratory experiments on food choice. In the present study, we were able to detect chironomid DNA in water mite bodies for the first time using molecular methods. Prey DNA was detected in virtually all Hygrobates fluviatilis (Hygrobatidae) that were fed on chironomid larvae after a starvation period of up to approximately 1 week. From the shortest interval (1 h after feeding) to the longest period after feeding (50 h) the relative amount of detected prey DNA was significantly reduced. In addition, there was a relationship between the relative amount of prey DNA and the assumed amount of the ingested prey (classified in categories of the dead prey which reflect the increasing ingestion of the mites and the decreasing body content of the prey individuals). The results of our study indicate that similar molecular analyses will be a powerful tool for diet investigations of mites from the field on various taxonomic resolutions of prey taxa. Moreover, the results of food selection experiments from the laboratory could be compared to evidence of predation by individuals from the field. For many mite taxa, especially ones which turned out to be difficult to breed in the laboratory (e.g. by unknown diet), the new methods might enable us to gain the first ever data on diet and thus may help us to consider the role of water mites in food webs more adequately in the future.Quelle: http://link.springer.com
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