Do mining activities significantly affect feeding behavior of freshwater benthic macroinvertebrates? A case study in South Sardinia (Italy)

We investigated the cascading effects of chemical contaminants on alder leaf detritus quality and the exploitation of this feeding resource by benthic macroinvertebrates (isopods, gastropods, and mayfly nymphs). Trophic behavior and energetics of benthic macroinvertebrates were used to evaluate the effects of contaminants on detritus exploitation. A two-way factorial nested experimental design was used to statistically quantify how leaf detritus origin (polluted and unpolluted streams) and the pollution level of the site selected for microbial conditioning of the detritus could affect the feeding resource quality for aquatic benthic macroinvertebrates, as measured by their trophic behavior (i.e. food selection) and exploitation (i.e. food ingestion). Alder leaves collected from a polluted stream in a former mining area (South-Sardinia, Italy) had Cd, Pb, and Zn concentrations up to 10 times that of leaves collected from an unpolluted stream. When benthic macroinvertebrates were given the option to choose, they all selected leaves from the unpolluted stream and/or those conditioned in the unpolluted stream. Ingestion rates were also significantly affected by both considered factors: leaf origin and conditioning. In addition, synergistic effects strongly increased the chemical contaminant stress on the leaf detritus quality. These results show that the terrestrial component of land–water ecotones affected by mining can be a relevant indirect pathway of chemical stress to benthic macroinvertebrate species

Response of benthic macroinvertebrate community decriptors to chemical pollution in the aquatic ecosystem of Fiume Grande and Punta della Contessa saltpans (Brindisi, Italy)

EnThe anthropogenic activities that take place in an area are reflected in the quality of the waters in the water bodies into which the area drains;these water bodies thus represent natural tools for monitoring the state of health of the whole catchment area.The objective of this study is to evaluate the sensitivity of benthic macroinvertebrate communities in aquatic ecosystems to perturbations linked to chemical pollution.To this end a study was conducted in the aquatic ecosystems located within the Site of National Interest of Brindisi,performing seasonal samplings in 9 field sites.The analysis of the benthic macroinvertebrate communities entailed taxonomic identification,determination of biomass and evaluation of the body condition of each individual sampled. Taxonomic and non-taxonomic community indices were derived,and their models of variation were described and compared on gradients of concentration of chemical contaminants in the area. The results indicate significant relations between the concentration of heavy metals and descriptors of the size spectra of benthic macroinvertebrates,suggesting that in aquatic ecosystems,descriptors linked to size can be a useful tool in support of bio-monitoring and assessment of ecological risk,considering their ease of application and sensitivity to perturbation pressures in an industrial area

The litter bag technique for studying detritus decomposition in aquatic ecosystems. A case study in the South of Italy, (Lake Alimini)

EnLeaf litter decomposition rates in aquatic ecosystems are known to be related to many different abiotic and biotic factors.A comparative analysis of inter and intra-habitat variations of detritus decay rates across ecosystem types was carried out in the Alimini lake complex (Italy)to assess the relevance of major ecosystem features to detritus processing rates.Overall,the spatial variability of leaf decomposition rates was more pronounced than temporal variability,decomposition rates in the stream being 3.6 and 5.2 times faster than in the freshwater lake and saltmarsh,respectively.Overall,environmental features were relevant factors affecting intra-and inter-habitat variation of reed decay rates

A unifying approach to allometric scaling of resource ingestion rates under limiting conditions

Individual resource ingestion rates depend on both individual body size and resource supply. A component of the latter, namely resource availability, is also body-size dependent. This raises the question of the adequacy of simple scaling laws to describe the body-size dependency of resource ingestion. Here we propose a model which integrates resource ingestion drivers by merging a scaling law for feeding metabolism and Holling's functional responses into a single mathematical framework. At any fixed level of resource supply, the model predicts a log-log concave-down relationship between resource ingestion rates and body size, rather than a simple scaling law. Deviations from the latter are accounted for by the body size dependency of resource limitations. Experimental and literature data describing patterns of perceived resource availability and individual intake rates under limiting conditions with increasing individual body size are used to validate the model's assumptions and predictions. The model inc..

Effetti della siccità sull'abbondanza e distribuzione dei macroinvertebrati

The role of disturbance on structuring animal communities is a central subject in the ecological research. In particular in the intermittent systems river, the drought event seems to determine the macroinvertebrate community structure. In such context, we analysed the macrobenthos of a Sardinia intermittent stream (Rio Pula, Cagliari). The study was carried out on 16 sites in 3 years (from 2000 to 2002) with seasonal samplings (spring and autumn) of the macroinvertebrate community. The results have shown a temporal stability of community and a spatial change of community structure along the river basin determined by drought frequency. Finally, patterns of spatial change in the guild composition seem to be partly in contrast with the River Continuum concept

The Lagoons of Corfu: multiple impacts, conservation strategies and economic exploitations

In the Island of Corfu there are seven lagoons which have different biological and chemical characteristics and also different impacts and human interventions. In this research, a preliminary description of the lagoons is reported using available data from the literature. The lagoons of Corfu have been poorly studied from the point of view of ecological functuins and biodiversity. Specifically the lagoons are: 1.Lagoon Korission, it is the largest lagoon of Corfu. Located in the southwest of the island has an area of 600hectares approximately. Works like a fish farm and is protected area Natura 2000. The main intervention of the lagoon is the increasing of the human activities in the area of the lagoon; 2. Lagoon Chalkiopoulou, the second largest lagoon of Corfu, it has a total size of 180 hectares. There was a fish farm fifteen years ago. It is estimated that the last seventy years the lagoon has lost about 1/3 of its extent. This lagoon has received the most and the major intervention is the reduction in the area in order to create the Airport of Corfu; 3.Lagoon Antinioti, it is located northeast of Corfu and it has a total size of 100 hectares with the marshland Kounoufadi which is part of the lagoon. Works like a fish farm and is included in the protected areas Natura 2000. The main interference of the area has been done on the part of the marshland Kounoufadi where twenty years ago have been put polders by the municipality of Corfu in order to build a Municipal Stadium; 4. Lagoon Alykes Lefkimmis, it is a small lagoon of about 30 hectares in the southeast of Corfu. Along with former Alykes Lefkimmis is included in the protected areas Natura 2000. There is not significant human intervention in the lagoon in addition with the former Saline of Lefkimmi (which forms a single ecosystem) for which the area has decreased due to residential use. Three small lagoons in the area of Erimitis which is in the northeast part of Corfu, there are 3 small lagoon ecosystems (Akoli, Vromolimni and Avlaki) located on the northeast coast of Corfu. Each of these has a size of 2-4hectares. The most remarkable is that the lagoon Akoli in the past served as a fish farm and had an artificial orifice communicating with the sea. Such abandonment of this orifice it is noticed a decrease in the depth of the lagoon

A macro-ecological approach to the study of the vulnerability of aquatic environments to nonindigenous species: a case study by the Virtual Research Infrastructure LifeWatch Italy

LifeWatch, the European Virtual Biodiversity Research Infrastructure, is a reference point for researchers, policy makers, public authorities and enterprises operating in the field of protection, management and the sustainable use of biodiversity and ecosystems. LifeWatch Italy has proposed a European-level case study designed to assess the vulnerability of aquatic and terrestrial ecosystems to the arrival of non-indigenous species (NIS), in order to demonstrate the functionality of the e-infrastructure and its potential. Here we present the results of a first analysis conducted, on a national scale, on NIS presence in various typologies of aquatic environments (freshwater, transitional and marine), aimed at verifying the link between vulnerability to NIS and human activities. Each of these environments is diversely affected by the NIS problem, which is of great interest both at national and international level, showing different rates of biodiversity alteration. To understand the mechanisms that cause the NIS success and to find adequate means of prevention, the LifeWatch community proposes a macro-ecological approach. It analyzes the drivers of NIS occurrence and the role played by climate change in facilitating their spread, so as to provide solutions that will lead to their reduction by applying effective measures for biodiversity conservation. The data used refer to a 30-year time span and include several taxonomic groups. All analyses were performed using dedicated R packages, which are one of the services provided by LifeWatch on the web

Metabolic rate and climate change across latitudes: Evidence of mass-dependent responses in aquatic amphipods

Predictions of individual responses to climate change are often based on the assumption that temperature affects individuals’ metabolism independently of their body mass. However, empirical evidence indicates that interactive effects exist. Here, we investigated the response of individual Standard Metabolic Rate (SMR) to annual temperature range and forecasted temperature rises of 0.6-1.2°C above the current maxima, under the conservative climate change scenario IPCC-RCP2.6. As a model organism we used the amphipod Gammarus insensibilis, collected across latitudes along the western coast of the Adriatic Sea down to the southernmost limit of the species’ distributional range, with individuals varying in body mass (0.4-13.57mg). Overall, we found that the effect of temperature on SMR is mass-dependent. Within the annual temperature range, the mass-specific SMR of small/young individuals increased with temperature at a greater rate (activation energy: E=0.48 eV) than large/old ones (E=0.29 eV), with a higher metabolic level for high-latitude than low-latitude populations. However, under the forecasted climate conditions, the large individuals’ mass-specific SMR responded differently across latitudes. Unlike the higher-latitude population, whose mass-specific SMR increased in response to the forecasted climate change across all size classes, in the lower-latitude populations, this increase was not seen in large individuals. The larger/older conspecifics at lower latitudes could therefore be the first to experience the negative impacts of warming on metabolism-related processes. Although the ecological collapse of such a basic trophic level (aquatic amphipods) due to climate change would have profound consequences for population ecology, the risk is significantly mitigated by phenotypic and genotypic adaptation