1,720,968 research outputs found
Le Saline di Tarquinia: analisi della comunità macrozoobentonica lungo il gradiente salino
No full textAnalisi del d15N come stima dell'input di azoto in ambienti marini: esperimento in mesocosmo
No full textEcosystem vulnerability to disturbance propoagation as revealed by food web structure: the role of species richness
No full textSite-scale isotopic variations along a river course help localize drainage basin influence on river food webs
No full textIn human-impacted rivers, nutrient pollution has the potential to disrupt biodiversity organisation and ecosystem functioning, prompting calls for effective monitoring and management. Pollutants, together with natural variations, can modify the isotopic signature of aquatic organisms. Accordingly, we explored the potential of isotopic variations as an indicator of drainage basin influences on river food
webs. We assessed stable N and C isotopes within six food webs along a river affected by multiple pollution sources. CORINE land cover maps and Digital Elevation Models (DEMs) were also applied to understand the impact on surface waters of anthropogenic
pressures affecting the catchment. N isotopic signatures of taxa fell in association with ammonium inputs from agriculture, indicating that nitrogen pollution was related to synthetic fertilizers. Isotopic variations were consistent across trophic levels, highlighting
site-specific communities and identifying taxa exposed to pollutants. This allowed us to locate point sources of disturbance, suggesting that food web structure plays a key role in pollutant compartmentalisation along the river. Thematic maps and DEMs helped understand how the anthropogenic impact on river biota is mediated by hydro-geomorphology. Thus, the integration of site-scale analyses of
stable isotopes and land use represents a promising research pathway for explorative nutrient pollution monitoring in human-impacted rivers
Posidonia oceanica habitat loss and changes in litter-associated biodiversity organization: A stable isotope-based preliminary study
No full text1.Posidonia oceanica (L.) Delile meadows are experiencing severe decline, with significant effects on P.oceanica meadow biodiversity, food webs and associated ecological processes. Despite the importance of this habitat, very little information with which to comprehend and predict the effects of habitat loss on the trophic traits of meadow-dwelling species is available.2.The study addressed the effect of changes in P.oceanica cover on the trophic niche of macroinvertebrate litter-associated species and on their consumption of various basal resources along the upper limit of a P.oceanica meadow in the central Tyrrhenian Sea.3.Census data and C and N stable isotope analysis were used to characterize changes in the trophic niche of species and the contribution of basal resources to food webs along a meadow coverage gradient.4.Falling P.oceanica cover was associated with lower species richness and animal density. In the low-coverage area of the meadow, the organic matter content of basal resources decreased, and the trophic generalism of species increased while their trophic niche overlap declined. In addition, consumption of living P.oceanica plants and epiphytes decreased, and consumption of sediment-derived organic matter increased.5.The results suggest that the community associated with P.oceanica litter is particularly sensitive to meadow degradation, which affects trophic structuring and nutrient pathways within the food web. © 2013 Elsevier Ltd
δ15N variation in Ulva lactuca as a proxy for anthropogenic nitrogen inputs in coastal areas of Gulf of Gaeta (Mediterranean Sea)
No full textWe tested the capacity of Ulva lactuca to mark N sources across large marine areas by measuring variation in its d15N at several sites in the Gulf of Gaeta. Comparisons were made with the macroalga Cystoseira amentacea. Variation of d15N values was assessed also in the coastal waters off the Circeo Natural Park, where U. lactuca and C. amentacea were harvested, as these waters are barely influenced by human activities and were used as reference site. A small fragment from each frond was preserved before deployment in order to characterize the initial isotopic values. After 48 h of submersion, U. lactuca was more responsive than C. amentacea to environmental variation and d15N enrichment in the Gulf of Gaeta was observed. The spatial distribution of d15N enrichment indicated that different macro-areas in the Gulf were affected by N inputs from different origins. Comparison of the d15N values of fragments taken from the same transplanted frond avoided bias arising from natural isotopic
Food web organization of Posidonia oceanica invertebrate community in fragmented and no-fragmented sites
No full textPosidonia oceanica meadows play a fundamental role on biodiversity organization. Despite the causes are complex and still discussed, P. oceanica meadows are experiencing a fragmentation process, particularly on coastal areas. In this study we addressed the effect of meadow fragmentation on detritus associated macroinvertebrates abundance and diversity and on the structure of detritus based food webs by comparing a no-fragmented portion of the meadow with a fragmented one in the coastal area of Tarquina (Vt), Italy (42°12’40’’N 11°41’55’’E). Macroinvertebrate samples were collected using 20g autochthonous P. oceanica litterbags, the sampling design included six replicates
litterbags placed in sampling sites in no-fragmented and fragmented areas of the meadow. To test the importance of autochthonous detritus quality in defining
habitat complexity and carrying capacity, also six 20g Phragmites australis leaf litterbags were placed in each site. Detritus based food webs parameters were determined by correlative analysis of macroinvertebrate census data, corrected by 13C and 15N values. The results presented are from a pioneering approach
to study invertebrate food web in P. oceanica meadow. The results emphasize the effect of fragmentation on community composition and biodiversity organization (food web)
Effects of terrestrial input on macrobenthic food webs of coastal sea are detected by stable isotope analysis in Gaeta Gulf
No full textStable isotope analysis (SIA) of carbon (δ13C) and nitrogen (δ15N) was used to analyse the macrobenthic food web dynamics in the Gulf of Gaeta (Tyrrhenian sea, Central Italy) under the influence of discharge from the river Garigliano. Specimens of macrobenthic invertebrates and organic matter (Phytoplankton, detritus and Sediment Organic Matter, SOM) were sampled in eight subtidal sampling sites in the Gulf and subjected to SIA. Bayesian Stable Isotope Mixing Models were used to quantify the proportional contribution of each basal resource to macrobenthic primary consumer diets. The food web topology of each sampling site was also reconstructed and the key food web metrics (connectance, linkage density, mean chain length) were calculated in order to detect potential effects of the river plume at all trophic levels. The δ13C signatures of basal resources indicated that bulk organic matter in the Gulf has two main inputs: a) autochthonous, derived from marine primary producers (phytopla
- …
