Search results for "biotic index"
showing 7 items of 7 documents
The role of watercourse versus overland dispersal and niche effects on ostracod distribution in Mediterranean streams (eastern Iberian Peninsula)
2016
Abstract The processes behind the heterogeneous distribution of species involve a combination of environmental and spatial effects. In the spatial context, stream networks constitute appropriate systems to compare the relative importance of two dispersal modes in aquatic organisms: overland and watercourse dispersal. In the present study, we analyzed the distribution of ostracod species in a river network in the eastern Iberian Peninsula, with variation partitioning between environmental and spatial factors, using Moran and Asymmetric Eigenvector Maps (MEMs, AEMs) as spatial variables. Our aims were to determine the relative importance of environmental and spatial control and to compare the…
Effectiveness of Posidonia oceanica biotic indices for assessing the ecological status of coastal waters in the Saronikos Gulf (Aegean Sea, Eastern M…
2017
Biotic indices are considered key assessment tools in most national and European policies aimed at improving the quality of coastal waters. At present, several Water Framework Directive (WFD)-compliant biotic indices based on the marine angiosperm Posidonia oceanica have been developed and applied in the Mediterranean Sea. In this study, we investigated the effectiveness of four different P. oceanica indices (POMI, PREI, Valencian CS, and BiPo) in evaluating the ecological status of coastal waters in a case study area of Greece. The evaluation, comparison, and validation of the Ecological Status Class (ESC) assessments obtained by each index were based on a set of eight common sites that en…
Effects of environmental and spatial variables on lotic ostracod metacommunity structure in the Iberian Peninsula
2015
The heterogeneous distribution of aquatic species in lotic environments has been studied little in terms of metacommunity theory. Previous empirical tests have found significant spatial and environmental effects in pond and lake communities, but this has not yet been clearly established for stream networks. We conducted a multi-season survey of mountain streams in the Iberian Peninsula. We recorded GIS and in situ environmental data and collected biological samples to determine ostracods and macroinvertebrates and identified 41 ostracod species, the most common belonging to genera Herpetocypris , Sarscypridopsis , and Ilyocypris . A generalized linear model analysis showed that thermal rang…
Use of artificial substrates for sampling benthic macroinvertebrates in the assessment of water quality of large lowland rivers
2004
The objective of this investigation was to evaluate the usefulness of the artificial substrate sampler in collecting macroinvertebrates for water quality assessment of Polish lowland rivers. This paper presents the results of a comparative study between two different sampling techniques, i.e. nettings filled with brick as artificial substrates and handnet sampling. The validity of applying the biotic index method is also demonstrated. The Belgian Biotic Index (BBI) method and the lower Nysa Kłodzka river were chosen for study. Macroinvertebrates were collected seasonally at five sampling sites. Although some invertebrate taxa revealed a specific preference for one of the two tested sampling…