1,721,004 research outputs found
Species-Area Relationship (SAR)models as tools for estimating faunal biodiversity associated with habitat builder species in sensitive areas: the case of the Mediterranean stony coral (Cladocora caespitosa)
No full textBiodiversity associated with the Mediterranean stony coral Cladocora caespitosa (Linnaeus, 1767)was investigated at three levels: “microscale”, focused on macrobenthic invertebrates within colonies; “mesoscale”, focused on epibenthic megafauna among colonies; “macroscale”, focused on associated ichthyofauna. The aim was to quantify associated diversity in terms of species richness, testing the efficiency of colony size (surface covered by a single colony)for the “microscale”, and colony density or total coral coverage for “meso-” and “macroscale” as predictors and the consistency of models based on Species-Area Relationship (SAR)for those estimations. At level of “microscale”, colony size was a good predictor, with richness of invertebrates increasing with the increasing of surface covered by each colony of C. caespitosa, following Arrhenius model. At levels of “mesoscale” and “macroscale”, richness of epibenthic megafauna and fish were not related neither to colony density nor total coral coverage, but to sampled area, and frequency-based estimates of richness were used. The importance of C. caespitosa varied according to the investigation level, with most of taxa richness detected at the level of “microscale”
Heavy metals, OCPs, PAHs, and PCDD/Fs contamination in surface sediments of a coastal lagoon (Valli di Comacchio, NW Adriatic, Italy): Long term trend (2002−2013) and effect on benthic community
No full textSurface sediments contamination (heavy metals, organochlorine pesticides, polycyclic aromatic hydrocarbons, polychlorinated dibenzodioxins and dibenzofurans) and benthic community of the Valli di Comacchio, were analysed from 2002 to 2013. Along the studied period, most of analysed pollutants did not exceed thresholds for Good chemical status of sediments. In 2008, a peak of contamination was observed, with total PAHs and OCPs exceeding their threshold. Considering metals, Ni and Cr exceeded their thresholds, but not the background levels for the area, suggesting natural enrichment; conversely Pb exceeded background levels for the area in many samples, but it exceeded its sediment quality thresholds only in few samples (2006, 2009, 2011). Conversely, the ecological status evaluated though AMBI and M-AMBI, was below the Good/Moderated thresholds established by WFD in most of the studied years. In the 11 yrs-study period, the benthic community showed a very weak response to chemical contamination
Ecological patterns of polychaete assemblages associated with the Mediterranean stony coral Cladocora caespitosa (Linnaeus, 1767): a comparison of sites in two biogeographic zones (Adriatic and Aegean Sea)
Full text linkThe Mediterranean stony coral Cladocora caespitosa (Linnaeus, 1767) is a well-known habitat builder, and as such hosts a
diversified faunal assemblage. Although polychaetes are one of the most abundant and diverse macrobenthic groups associated
with C. caespitosa colonies, our knowledge of their ecological features in this association is still limited. The aim of this paper
was to gather and compare the most comprehensive data available on polychaetes associated with C. caespitosa in the Adriatic
and the Aegean Seas, and to test for differences between these geographic areas. To this end, differences were tested in terms
of: (i) richness and structure of polychaete assemblages; (ii) feeding and functional traits of assemblages; (iii) the main factors
influencing those aspects, (iv) the relationship between polychaete assemblages richness and Cladocora colony size, estimated
richness. Differences were observed between the Adriatic and the Aegean assemblages, in terms of richness, species composition
and relative proportion of the dominant feeding guild (filter feeders most abundant in the Aegean and carnivores in the Adriatic)
and motility mode (sessile most abundant in the Aegean and motile in the Adriatic). Conversely, cosmopolitan and Atlanto-Mediterranean species dominated the assemblages in both geographic areas, and the same Species-Area Relation model proved to be effective for richness estimation in both geographic areas
When the levee breaks: Effects of flood on offshore water contamination and benthic community in the Mediterranean (Ionian Sea)
No full textIn the last few years extreme weather events, including changes to storm frequency and intensity, have increased across all continents. In this note we assessed, for the first time in the Mediterranean Sea, the impact of a violent storm and consequent flood on offshore water contamination and benthic community along the Calabrian coast (Ionian Sea). Three sites (at 500, 1000, and 2000 m off the coast) were sampled along three parallel transects in 2013, 2014 (before), and 2015 (after the flood). After the flood, metals (especially Al, CrVI, Ni, Cu, Zn) in the water column increased in concentration. The flood affected the structure of the benthic community, causing a decrease of diversity, the dominance of few opportunistic species, and the decrease of M-AMBI values
Long-term variability of macrobenthic community in a shallow coastal lagoon (Valli di Comacchio, northern Adriatic): Is community resistant to climate changes?
No full textA time series data of macrobenthic invertebrates of Valli di Comacchio lagoon (northern Adriatic) from 1996 to 2015, was analysed using Biological Traits Analysis, structural indices, AMBI and M-AMBI indices, with a twofold aim to: firstly, test the resilience of the system, and, secondly, test the influence of climate changes, in terms of temperature and precipitation pattern, on macrobenthic dynamics. Along the studied period macrobenthic community showed marked fluctuations, in terms of richness, diversity, biological traits and ecological groups, which could be related with environmental instability of the lagoon. At the same time, a general tendency towards a deterioration of ecological condition of the lagoon was observed, with a general decrease in species richness, diversity, percentage of sensitive species, and a general increase in the proportion of the more opportunistic trait modalities, such as deposit feeders, burrowing, infaunal and short living animals. Increasing yearly temperature explained only a small part of the variability of macrobenthic community, in terms of biological traits and diversity indices, and this was likely due to the effect of natural fluctuations of environmental parameters and anthropogenic disturbance. Nevertheless, all metrics used are consistent in identifying the response of benthic community to a severe disturbance, likely related with the summer heatwave in 2003. Less marked signs of disturbance were observed also in relations to the thermal anomaly of 2012. Biological Traits Analysis combined with more classical structural and ecological indices, proved to be efficient in identifying temporal changes of the community. Our results suggest that the expected increase in frequency, magnitude and duration of heatwaves could pose serious threat to the resilience capacity of lagoonal macrobenthic community
Combined climate and chemical stressors
Full text linkFicopomatus enigmaticus, a reef-forming serpulid, has emerged as a promising candidate for biomonitoring and ecotoxicology studies. Recent research has focused on adult stress responses, highlighting the need to understand population-specific responses. This study employed a multi-biomarker approach to investigate how F. enigmaticus adults from two populations in the NE Adriatic (Site A) and NE Tyrrhenian (Site B) responded to chronic exposure to heat and chemical stress (dimethyl sulfoxide, DMSO), individually and in combination. The analysis detected significant differences in protein content and the activities of superoxide dismutase (SOD) and glutathione S-transferase (GST) between populations. Notably, no oxidative damage (measured as lipid peroxidation, LPO) was detected in any population or treatment. Similarly, no significant differences were detected in the integrated biomarker response index (IBRv2i). However, lower IBRv2i values at Site A suggested reduced stress conditions, possibly indicating that this site may have lower baseline stress. Overall, treatment effects were limited and site-specific: only the combined heat and DMSO exposure at Site A lowered GST activity compared to heat stress alone. Nevertheless, both populations exhibited broadly similar biochemical response patterns to stress. Our findings deepen the understanding of stress physiology in F. enigmaticus, underscoring the ecological importance of multi-stressor approaches in environmental monitoring
Comparison of benthic indices for the evaluation of ecological status of three Slovenian transitional water bodies (northern Adriatic)
No full textBenthic indicators are important tools for the classification of coastal and transitional water bodies. The aim of the work was to assess for the first time the Environmental Status (ES) of Slovenian transitional waters, comparing the following biotic indices: richness, Shannon-Weaver diversity, AMBI, M-AMBI, BENTIX and BITS indices. A total of 13 stations were sampled with a Van Veen grab, in three ecosystems in the northern Adriatic. Samples were sieved and sorted, invertebrates identified and counted. The anthropogenic impact was estimated with professional judgement. Richness and diversity showed a good response to anthropogenic pressure. Conversely, indices based on sensitivity/tolerance groups did not showed a clear distinction between more and less impacted ecosystems. In particular BENTIX underestimated the ES, while with BITS there was a overestimation. The best evaluation was obtained with M-AMBI, because even if based on a sensitivity/tolerance approach, it considered also the structural aspect of the community
Spatial patterns of macrobenthic alpha and beta diversity at different scales in Italian transitional waters (central Mediterranean)
Full text linkBiodiversity is a multidimensional concept encompassing many scales of variation, originally partitioned into three components: alpha, the number of species in a single sampling unit, beta, the variation in species identities from site to site, and gamma, the overall number of species within a defined geographical area. Investigations on macrobenthic assemblages in transitional waters have been traditionally focused on alpha- and gamma-diversity, largely neglecting beta-diversity. The aim of the work was to identify patterns of variation of macrobenthic invertebrates in transitional waters from 18 different Italian lagoons (central Mediterranean) at three different scales (site, lagoon and region), combining classical and multivariate measures for partitioning diversity. Classical alpha, beta and gamma diversity were calculated, together with measures considering also relative species abundances. The highest variability of macrobenthic assemblages was observed at the intermediate scale (among lagoons), with significant variations in terms of both alpha and beta diversity. At the smallest analysed scale (among sites) the variability was mainly in terms of beta diversity, whereas at the biggest scale (among regions), the variability was mainly in terms of alpha diversity. At the intermediate scale (among lagoons) alpha diversity was influenced by the regional species pool, with one exception (Grado-Marano lagoon) where the habitat heterogeneity and beta diversity played a major role. Beta diversity, measured as variability of dispersion with Jaccard resemble measure, was consistent with results obtained with the original formulation of Whittaker. Considering alpha diversity, a different pattern of variability was observed considering relative abundances, whereas considering beta diversity, no significant differences were observed in terms of relative species abundances. The patterns of macrobenthic assemblages among lagoons in terms of both alpha and beta diversity resulted from the complex interaction of different drivers acting in a framework of geographical variability. Alpha diversity was mainly influenced by salinity, but other factors (size, confinement, trophic status and sediment composition) were likely to contribute. Beta diversity was mainly influenced by habitat heterogeneity, deriving from different environmental parameters, such as trophic condition and water confinement. Our results support the usefulness of portioning diversity in alpha, beta and gamma components, and of combining different univariate and multivariate measures of dispersion, to consider patterns of richness and relative abundances separately
The efficiency of Taxonomic Sufficiency for identification of spatial patterns at different scales in transitional waters
Full text linkTaxonomic Sufficiency (TS), the use of coarser taxonomic resolution in monitoring plans, has been receiving increasing attention in last years. A comprehensive dataset of macrobenthos from 18 Italian lagoons in a range of different latitude, typology, salinity and surface area, was analysed in order to test the efficiency of TS, in terms of correlation between patterns at level of species and patterns resulting from different levels of taxonomic aggregation. First, TS was applied on a range of univariate indices, providing complementary information on macrobenthic community, in order to test the efficiency, in a contest of different taxonomic composition, and different number of lower taxa belonging to the same higher taxon in each lagoon. Then, TS was applied on multivariate analyses, in order to test whether the efficiency changes between two different scales: local (comparison of sites nested within each lagoon) and regional (comparison among lagoons), and with different data transformation. The patterns resulting from univariate indices and multivariate analyses, at both local and regional scales, were retained till family level, despite the different levels of taxonomic composition and different number of lower taxa belonging to the same higher taxon of different lagoons. Nevertheless, the correlation values among matrices and the effect of data transformation differed between regional and local scales. Our results support the efficiency of TS until family level, but at the same time underline the need of scale- and region-specific baseline knowledge prior application of TS in lagoons
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