Matteo Pallottini

Deformities of chironomid larvae and heavy metal pollution: From laboratory to field studies

Mouthpart deformities of Chironomus riparius larvae (Diptera) have been investigated to evaluate the toxic effects of contamination by heavy metals in the Genna Stream (Central Italy), situated in an area subjected to intensive swine farms (40000 heads). The livestock farming (fertirrigation) contributes to metal pollution of the Genna Stream with an increase of copper, zinc, cadmium, chromium and nickel in the sediments of the downstream stations. The incidence of mentum deformities was very high at all sampling stations, about 56%. The highest values of deformities were found in the intermediate river reach (St. 3: 65%) and in March (66%), mainly due to an increase in severe deformities. The high incidence of severe deformities (30%) is attributed to the high pollution level by heavy metals in the sediments, in particular to copper and zinc, which showed the highest average value at St. 3 and in March. This field study reflected the relationships between sediment metal concentrations and chironomid mouthpart deformities, previously observed in laboratory tests, and highlighted these deformities as toxicity endpoints. This feature paves the way for their use as an effective tool in freshwater bioassessment monitoring programs to evaluate the toxic effects of metal contamination in freshwater ecosystems.

Heavy metals bioaccumulation in selected tissues of red swamp crayfish: An easy tool for monitoring environmental contamination levels

In this paper we explored the heavy metal bioaccumulation (Cd, Cu, Pb and Zn) in Procambarus clarkii, a crayfish recently suggested as a potential bioindicator for metals pollution in freshwater systems. The present study is focused on crayfishes populations caught in a heavily polluted industrial and in a reference sites (Central Italy), though the results are generalized with a thorough analysis of literature metadata. In agreement with the literature, the hepatopancreas (Hep, detoxification tissues) of the red swamp crayfish showed a higher concentration of heavy metals in comparison to the abdominal muscle (AbM, not detoxification tissues) in the sites under scrutiny. Hep/AbM concentration ratio was dependent on the specific metal investigated and on its sediment contamination level. Specifically we found that Hep/AbM ratio decreases as follows: Cd (11.7)>Cu (5.5)>Pb (3.6)>Zn (1.0) and Pb (4.34)>Cd (3.66)>Zn (1.69)>Cu (0.87) for the industrial and reference sites, respectively. The analysis of our bioaccumulation data as well as of literature metadata allowed to elaborate a specific contamination index (Toxic Contamination Index, TCI), dependent only on the bioaccumulation data of hepatopancreas and abdominal muscle. In the industrial site, TCI expressed values much higher than the unit for Cd and Cu, confirming that these metals were the main contaminants; in contrast for lower levels of heavy metals, as those observed in the reference site for Cu, Zn and Pb, the index provided values below unit. TCI is proposed as a useful and easy tool to assess the toxicity level of contaminated sites by heavy metals in the environmental management.

Invertebrate diversity in relation to chemical pollution in an Umbrian stream system (Italy)

We used self-organizing maps (SOM, neural network) to bring out patterns of benthic macroinvertebrate diversity in relation to river pollution. Fourteen stations were sampled over various seasons in the Nestore drainage basin (Central Italy) and characterized for macroinvertebrate communities, nutrient and heavy metal concentrations. Physicochemical variables were introduced into a SOM previously trained with macroinvertebrate data. Patterns of communities matched spatial and seasonal changes in environmental conditions, including water chemistry related to economic activities in the catchment. Although our analyses did not allow us to establish the specific effect of any given environmental parameter upon macroinvertebrate community composition based on the field study, they enabled us to map the ecological health of river ecosystems in a readily interpretable manner.

An efficient semi-quantitative macroinvertebrate multimetric index for the assessment of water and sediment contamination in streams

Abstract Environmental issues and their associated legislative pressures are demanding, especially regarding costs, limited budgets, and data collection efforts. The development of effective biotic indices for monitoring generated via comprehensive data collection within human-impacted landscapes can support district- to regional-level environmental management plans. We designed a macroinvertebrate multimetric index that fulfills the requirements of the EU Water Framework Directive and measures ecological health as a deviation from a reference state, taking into consideration water and sediment contamination in streams of Central Italy. Macroinvertebrate samples were obtained by a semi-quantitative technique. The Semi-quantitative Multimetric Index (SMI) we developed has a high discrimination efficiency (reference vs. impacted sites), high stability (i.e., low coefficient of variation) at reference sites, and low specificity regarding the environmental variables reflecting contamination. The SMI is composed of 4 metrics weighted by their discrimination efficiency against reference conditions: number of families, score of the biological monitoring waters pollution index (SBWMP), Margalef’s diversity index, and relative richness of shredders. These metrics that best distinguished reference from impacted sites were selected from 71 metrics divided into 4 categories (one metric for each category): richness/abundance, tolerance, diversity, bioecological traits. The SMI exemplifies a cost-effective method that could complement supranational techniques because it is robust in terms of biological, ecological, and socioeconomic contexts used to generate it; requires little effort for the data collection; and responds to a large number of environmental stressors. To ensure comparability, however, we recommend calibrating the new SMI index against the national index currently in use.