Search

The effects of cement consolidated phosphogypsum (PG) on marine organisms was investigated under natural conditions in four 1000 m2 estuarine ponds. Two ponds were seeded with 160 kg of PG arranged in aggregations of blocks and two ponds received similar mass of sand/cement blocks. Meiofauna were sampled quarterly and PG did not affect total meiofauna or major taxa (nematodes and copepods) density. Abundant species of copepods either were slightly increased in ponds with PG or were inconsistently affected. All ponds were drained after one year. Three species of macroinvertebrates and 15 species of fishes were collected. Diversity indices showed modest but inconsistent variation among ponds. Only Pond 1 (control) and Pond 4 (experimental) had similar species abundances and all ponds showed unique distributions of biomasses among species. Thus, no differences in community structure attributable to the presence of PG could be detected among benthic invertebrates, natant invertebrates, or fishes.

The aim of this work was to study: 1) the welfare in breeders of clam (Venerupis philippinarum and Venerupis decussata) using different biomarkers (cortisol, stress oxidative biomarkers, detoxification enzymes); 2) the reproduction and the larval development of these molluscs. The first study evaluated the variation of cortisol in clams subjected to the following stress conditions: anoxia and fasting. The study evidenced a tendency in the increase of cortisol in the animals under anoxia and a decrease in the animals under fasting conditions. In a successive work was evaluated the general morphology and the oxidative stress response in clams sampled at different sites of the Venice Lagoon. The histological evaluation revealed the presence of the parasite Perkinsus olseni in animals from all sites, with an intense immunitary response of the hosts. The hemocytes, that participate at the infiammatory response, showed an intense immunopositivity to several antibodies of the oxidative stress. The bivalve molluscs are often used as biondicator of environmental pollution, so we decided to evaluate the expression of two genes involved in the detoxification process of xenobiotics, in animals treated with different concentrations of benzo(a)pyrene. The expression of GSTr evidenced a significant increase of mRNA in the animals treated with the highest dose, but the analysis of CYP4 expression did not evidence differences among treatments. In treated animals, the histopatological analysis revealed an increase of a particular type of cells involved in the detoxification process of molluscs called brown cells. In the second part of the work we investigated about the reproduction of these bivalves using an histological approach to evaluate the gonad maturation and a radioimmunoassay method to analyse the sex steroids variation. The steroids progesterone, 17β-estradiol and testosterone resulted involved in the gonad maturation of the clams. The histological analysis revealed a different time of maturation of the two species of clams. The study of the larval development revealed useful information about the larval management.

Since May 1995 an air quality bio-assessment by epiphytic lichens has been carrying out within Canton Ticino. The research method is based on the "lndex of Atmospheric Purity" (I.A.P.). The worst air quality (O < I.A.P. < 30) was detected in the centre of the main towns and in the surrounding areas while the highest values of the I.A.P. (I.A.P. > 50) were observed in the Western part of the Canton, on mountain belt. Moreover, the Ecological lndices of Wirth have been evaluated: through a floristic analysis it has been possible to check the influence of pH and nitrogen enrichment of substrata on lichen distribution. Our observations confirm previously reported data: pH driving forces are a compromise among secondary substratum eutrophization (increasing pH), acid rains and tree trunk essudates. Considered this, till now, the Canton Ticino does not show any significative difference with the contiguous ltalian zones. The research is still in progress.