1,720,975 research outputs found
Detritus based food web along a sewage disturbed urban river trait: stable isotope analysis (d13C and d15N ) for trophic niche estimation
No full textδ13C range to study evolutionary traits association in predator-prey relationships: niche width-mobility-predation risk.
No full textFood niche width explains difference of detritus-based food web between aquatic and terrestrial contexts? An analysis of structural properties and robustness using stable isotopes.
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δ15N and δ13C variations in detritus and fungi during decomposition: a laboratory study.
No full textLe Saline di Tarquinia: analisi della comunità macrozoobentonica lungo il gradiente salino
No full textTest non parametrico per l'analisi di reti trofiche a base detrito in differenti contesti ambientali
No full textDifferent temperature tolerance of northern and southern European populations of a freshwater Isopod Crustacean species (Asellus aquaticus L.)
No full textTemperature is a major factor for ectothermic organisms, directly affecting biochemical and physiological processes. The increase in temperature and its effects have prompted many climate change studies, many of which focus on latitudinal gradients as they readily provide contrasting thermal regimes. In this study we evaluated the response in terms of growth, survival, and reproduction rates of two latitudinally separate populations of Asellus aquaticus (L.) to high temperature (30 degrees C). The comparisons revealed i) differences between the two populations, with higher tolerance found in the southern group, as well as between genders and body size classes. Only individuals from the southern population were able to complete the biological cycle at 30 degrees C, and no individuals from the northern population survived after 60 days; ii) differences between life stages: the survival rate of juveniles was greater than that of adults and the southern population had the highest proportion of temperature-resistant juveniles. The results confirm the importance of body size in the response to rising temperature and suggest that life stage should be taken into account in thermal adaptation studies. Analyses of intraspecific variability across different thermal regimes associated with the different latitudes illustrate how rising temperature can affect biological traits
Stable isotope variation in macroinvertebrates indicates anthropogenic disturbance along an urban stretch of the river Tiber (Rome, Italy)
No full textRunning waters in urbanized areas are large-scale systems of anthropogenic energy dissipation that receive effluents from point and diffuse sources, potentially inducing changes in organic matter decomposition and deposition and thus modifying river metabolism and the feeding patterns of inhabiting populations. Based on the hypothesis that anthropogenic disturbance provides important trophic constraints that influence the trophic niches of local communities, stable isotopes analysis was used to evaluate possible alterations in resource assimilation by aquatic species in response to diffuse and point sources of pollution from the city of Rome. For this purpose, the isotopic signature (15N and 13C) of detritus-based benthic communities and fish was determined upstream and downstream of two wastewater treatment plants (WWTPs) located before and after the urban stretch of the river Tiber. Community-wide metrics as the carbon range and convex hull area encompassing all taxa in a 15N and 13C bi-plot were used to measure the species' niche width and overlap. Differences were found between the upstream and downstream signatures, regarding the 15N and 13C of both detritivores and predators. The differences were found to be more pronounced at the southern WWTP, located downstream of the city. The lower 15N in macroinvertebrates at the WWTP-impacted sites reflected the lower 15N of suspended particulate organic matter and was associated with higher inorganic and organic loads. The decreasing range of 13C values in macroinvertebrates and fish indicated a narrowing of the niche width downstream of the treatment plants, particularly downstream of the urban area itself. The effects were stronger on detritivores than predators due to direct incorporation of the sewage-derived material that dominated the locally available food sources. These data suggest that isotopic signals coupled with community-wide metrics can be used as functional indicators of treated and untreated sewage impacts on aquatic communities even when the primary targets (species abundance and community structure) appear to be largely unaffected
Movement of three aphidophagous ladybird species between alfalfa and maize revealed by carbon and nitrogen stable isotope analysis
No full textThe movement between alfalfa and maize of three of the most common aphidophagous coccinellids in southern Europe was determined using carbon and nitrogen stable isotope analysis at four periods during the growing season. The isotope analysis revealed movement between alfalfa and maize but patterns were different between the three species. While Coccinella septempunctata L. (Coleoptera: Coccinellidae) only moved from alfalfa to maize, Propylea quatuordecimpunctata L. (Coleoptera: Coccinellidae) continuously dispersed between the two adjacent crops. Hippodamia variegata Goeze (Coleoptera: coccinellidae) showed an intermediate pattern. Results suggest that, while alfalfa acts as a source of the three species to maize, maize also plays a role as a source of P. quatuordecimpunctata and
H. variegata to alfalfa. The specific movement traits that emerged for the three coccinellid species suggest that crop management affects them differently and point out that the association between crops is very valuable for improving coccinellid biological control services
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