1,721,019 research outputs found
Biological, chemical and ecotoxicological assessments may not provide consistent estimates of the ecological status of the benthic environment
No full textBiological, chemical, and ecotoxicological assessments using benthos provide different and complementary measures of lake ecological status
No full textThe Water Framework Directive (WFD) aims to monitor continental water bodies in Europe to achieve good ecological status. Indexes based on biological quality elements (BQEs), ecotoxicological tests, and chemical characterizations are commonly used with standardized protocols to assess sediment quality and the associated risks. Here, we compare the results of quality assessment of benthic macroinvertebrates as BQEs as required by theWFDwith the results of ecotoxicological tests and assessment of selected persistent organic pollutants (POPs) in sediments of the same eight water bodies in Italy. The aim was to verify if the assessment of quality through macroinvertebrates through POPs analyses and ecotoxicological tools can yield comparable, overlapping, or complementary results. We used the Benthic Quality Index (BQIES) for macroinvertebrates (two different applications), legacy POPs (dichloro-diphenyl-trichloroethane and metabolites (DDTs) and polychlorinated-biphenyls (PCBs), and the emergence ratio (ER) and development rate (DR) for ecotoxicology. The results showed that the two indices within each approach were highly correlated, but between approaches, each result can lead to a completely different scenario, with rather different results of the assessment of ecosystem quality. The most striking result was that very few significant correlations existed between sediment quality assessment through macroinvertebrates and the risk assessment through analyses of micropollutants and ecotoxicological tests. The highest absolute r-value (0.81) was for the correlation between the BQIESbottom index and PCBs for micropollutants, whereas all other pairwise comparisons between indices had r-values ranging between 0.07 and 0.53. Our analysis calls for a caveat in the blind application of one or only a few indices of water/sediment quality, as the results of a single index may not represent the complexity of a freshwater ecosystem
I laghi di montagna come indicatori dei cambiamenti globali: le ricerche nei siti della rete LTER-Italia
No full textTesting the Use of Standardized Laboratory Tests to Infer Hg Bioaccumulation in Indigenous Benthic Organisms of Lake Maggiore (NW Italy).
Full text linkThe chronic toxicity of mercury essentially derives from its strong tendency to biomagnify along food webs. For this reason, the European regulatory framework establishes an environmental quality standard for Hg based on the total Hg concentration in prey fish to protect top predators. A considerable part of the Hg burden of prey fish can come from the ingestion of benthic organisms that, in the presence of contaminated sediments, may remobilize substantial amounts of Hg towards the pelagic food webs. The present study evaluated whether Hg accumulation in assemblages of indigenous chironomids and oligochaetes could be predicted using standardized laboratory bioaccumulation tests with Chironomus riparius and Lumbriculus variegatus. Indigenous chironomids and oligochaetes were recovered at different sites in a lake suffering from legacy Hg pollution and analyzed for total Hg content. Sediment aliquots from the same sites were used to assess Hg bioaccumulation using laboratory-reared C. riparius and L. variegatus. Mercury concentrations in indigenous versus laboratory organisms showed a good correlation (p < 0.05; Spearman correlation test) only in the case of C. riparius versus indigenous chironomids, suggesting the possibility of using linear regressions to predict Hg accumulation by these benthic invertebrates. Further research needs and caveats as to the applicability of the present results to other aquatic systems are identified and discussed
Primi risultati riguardanti lo studio delle comunità macrozoobentoniche nella Riserva Naturale Regionale della Foce dell'Isonzo (Friuli Venezia Giulia, Italia Nord-Est Italia)
No full textImpacts analysis of alien macroinvertebrate species in the hydrographic system of a subalpine lake on the Italian–Swiss border.
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Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Diversity, distribution and ecology of water mites (Acari: Hydrachnidia and Halacaridae) in high Alpine lakes (Central Alps, Italy)
No full textInformation on water mite assemblages from high elevation lentic biotopes is scant. A
survey of 14 small Alpine lakes located between1900 and 2400 m a.s.l. in Italy resulted in the
discovery of 17 species of Hydrachnidia and a single species of freshwater Halacaridae. Arrenurus
conicus and Lebertia tuberosa were the most widespread and abundant species; Lebertia sefvei,
Lebertia rufipes, Oxus setosus, Panisus torrenticolus and Sperchon glandulosus were also widely
distributed but relatively less abundant. Atractides fissus and Arrenurus conicus are recorded for the
first time from Italy. In contrast to mid/low elevation lakes and ponds, water mite assemblages of
alpine lakes are less diverse and are composed mainly of rheo- and crenobiontic taxa, most of which
are cold-stenothermic. Typical standing water dwellers represented only a small fraction (23%) of
the species sampled. A principal component analysis conducted on lake environmental variables
resulted in a clear separation of the lakes mainly based on ionic contents, pH and temperature.
Water mites seem to be less influenced by these factors than by temperature fluctuations and
habitat stability and heterogeneity. We conclude with some considerations of the influence of
abiotic and biotic factors on the altitudinal and latitudinal distribution pattern of water mites
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