N. Nesto

Field application of biochemical markers and a physiological index in the mussel, Mytilus galloprovincialis: transplantation and biomonitoring studies in the lagoon of Venice (NE Italy).

A number of biochemical markers and a physiological index were measured in mussels, Mytilus galloprovincialis, transplanted or native to five different contaminated sites in the lagoon of Venice. Mussels from Pellestrina, a reference site in the adjacent Adriatic Sea, were transplanted for 6 weeks to areas of the lagoon where indigenous mussels were also collected. As biochemical indices, superoxide dismutase (SOD), catalase, aldehyde dehydrogenase (ADH) and NADPH cytochrome c reductase (NADPHcred) were measured in mussel digestive gland; survival in air as a physiological index was also determined. Biomarker responses varied among sites and between indigenous and transplanted animals. Significant induction of catalase and SOD was shown in animals transplanted to the urban sites of Salute and Chioggia, respectively. In indigenous mussels, induction of SOD and NADPHcred was seen in animals from the polluted site of Treporti and the heavily contaminated industrial area of Marghera. The overall biochemical data indicate significantly higher activity for ADH in transplanted animals in comparison with indigenous ones which, in contrast, present an increase in SOD. As regard survival in air, control mussels did not seem to be healthier in comparison either with transplanted or indigenous ones, suggesting that pollution has no effect on this parameter.

Biochemical and histochemical responses to environmental contaminants in clam, Tapes philippinarum, transplanted to different polluted areas of Venice Lagoon, Italy.

In this study the clam, Tapes philippinarum, a filter-feeding bivalve living in soft bottoms, was used to investigate the water/sediment pollution in Venice Lagoon (Venice, Italy), a heavily urbanised and industrialised area. To this end, clams collected from indigenous populations in a clean farming area (Val Dogà) were transplanted into a relatively low contaminated site (Palude della Rosa) and in a heavily polluted area (Porto Marghera), for 5 weeks. A range of possible induced stress indices were measured, on the basis of potential toxicity mechanisms, including specific enzymatic activities [Bap hydroxylase and NADPH cytochrome c reductase, superoxide dismutase, catalase, glutathione peroxidase and propionaldehyde dehydrogenase (PDH)] and general cellular responses (lysosomal latency). Moreover, chemical analyses (polychlorinated biphenyls, polycyclic aromatic hydrocarbon, DDTs) were carried out on sediments and animal tissues at the beginning and end of the transplantation experiments. The chemical results show an active bio-accumulation activity from sediment in clams translocated to the most polluted area. Correspondingly, biological data indicate marked effects on PDH activity and latency in T. philippinarum from the same site. In contrast, no similar pattern has been observed in the other considered indices, possibly due to antagonistic effects of the complex contaminant mixture present in the environment.

Preliminary results of a field study on some stress-related parameters in Tapes philippinarum naturally infected by the protozoan Perkinsus sp.

Abstract The aim of the present work was to investigate the possible use of the clam Tapes philippinarum—a filter-feeding bivalve living on soft bottoms—in the monitoring of sediment pollution in the Lagoon of Venice (North-East Italy). To this end, two clam populations, exposed to different environmental conditions (a relative clean site and an industrial polluted area), have been monitored for the prevalence of the protozoan parasite Perkinsus sp. as well as for several biological parameters commonly used as determinants of contaminants exposure. First results showed a low prevalence, higher in the clean site, but a very diffuse distribution of the parasite throughout the two populations. Nevertheless, greater digestive cells height and longer lysosomal latency time were observed in clams from the clean area. As for the physiological stress-related parameters, even if clearance rates were always higher in these clams, scope for growth values indicated a more complicated biological response.

Is the polychaete, Perinereis rullieri (Pilato 1974), a reliable indicator of PCB and PAH contaminants in coastal sediments?

A field survey in a transitional environment (lagoon of Venice, Italy) and a laboratory exposure experiment were carried out to validate the use of polychaetes, Perinereis rullieri, as indicators of PCB and PAH contaminants in the sediments. Results from the field study showed that PCBs, predominantly the hexa- and hepta-chlorinated biphenyls, were promptly bioaccumulated in the tissues of P. rullieri, whereas PAH levels were generally low and fluctuating among seasons. Organisms experimentally exposed to natural polluted sediments bioaccumulated all the examined PCB congeners, whereas those exposed to the reference sediments were able to reduce them, at least to some extent. A PAH depletion was always observed, although the time variations for the single compounds differed from each other. The biomarker malondialdehyde (MDA), evaluated both in native and in treated organisms, was helpful as a supporting parameter in elucidating their oxidative stress condition, although depending on numerous natural confounding factors.

Evaluation of Biological Stress Indices in Tapes philippinarum from the Lagoon of Venice through Monitoring of Natural Populations and Transplantation Experiments

Monitoring of natural populations of the clam Tapes philippinarum from two sites in the Lagoon of Venice was carried out together with a transplantation experiment. The sites were chosen for their different hydrological conditions and pollution levels. Several physiological and histochemical stress-related parameters have been measured. Clearance rate and scope for growth are significantly affected by higher anthropogenic contamination levels acting on natural clam beds, though they are not responsive in transplanted animals after a six-week exposure. On the contrary “survival in air” response and lysosomal latency time are confirmed as early warning indices, particularly suitable for both monitoring approaches. Clam T. philippinarum is proposed as an indicator species in order to obtain an integrated biological evaluation of coastal seawater and sediment quality.

Biochemical and behavioural effects of hydraulic dredging on the target species Chamelea gallina

This study is focused on evaluating biological effects on the target species Chamelea gallina as a result of repeated exploitation of clam beds by hydraulic dredging. A biomarker approach was adopted and two physiological indices were applied: adenylate energy charge (AEC) (biochemical level) and reburrowing behaviour (organism level). The aim was to investigate the biological response to various types of fishing, i.e., commercial systems using water at high pressures (HP), and experimental systems at lower pressures (LP) in the field, and to evaluate the response of clams to mechanical stress in the laboratory. Field results showed that HP-treated clams exhibited significantly lower levels of AEC compared with LP treatments. A similar trend was shown by reburrowing behaviour; HP-treated clams reburrowed less. Laboratory results were less clear: a very low level of AEC was measured in both control and treated clams. These poor conditions in foot muscle did not indicate worsening at organism level, as no dead or dying clams were recorded throughout the experiment. However, repeated mechanical stress reduced the percentage of reburrowing clams, which suggested that harvesting may affect reburrowing behaviour.

An ecotoxicological approach to evaluate the effects of tourism impacts in the Marine Protected Area of La Maddalena (Sardinia, Italy)

In the Marine Protected Area of La Maddalena Archipelago, environmental protection rules and safeguard measures for nautical activities have helped in reducing anthropogenic pressure; however, tourism related activities remain particularly significant in summer. With the aim of evaluating their impacts, the biomarker approach using transplanted Mytilus galloprovincialis as sentinel organisms coupled with POCIS deployment was applied. Mussels, translocated to four marine areas differently impacted by tourism activities, were sampled before, during and after the tourist season. Moreover, endocrine disruptors in passive samplers POCIS and the cellular toxicity of whole POCIS extracts on mussel haemocytes were evaluated to integrate ecotoxicological information. Lysosomal biomarkers, condition index and mortality rate, as well as metals in tissues suggested an alteration of the health status of mussels transplanted to the most impacted sites. The cellular toxicity of POCIS extracts was pointed out, notwithstanding the concentrations of the examined compounds were always below the detection limits.

Effects of hydraulic dredging on target species Chamelea gallina from the northern Adriatic Sea: physiological responses and shell damage

The impact of experimental dredging was assessed on the venus clam Chamelea gallina from seabeds off the Lagoon of Venice. Commercial-sized clams were collected using high water pressure and mechanical sorting (HP), as in professional fishing, and low water pressure without sorting (LP). To highlight the effects of acute stress due to the different approaches in harvesting clams, various biological responses were evaluated at both organism and cell level. Filtration and respiration rates showed opposite behaviour, the former significantly decreasing, the latter increasing, when mechanical stress was higher. Consequently, lower values of scope for growth in HP clams were observed. The survival in air test exhibited significantly lower median survival time values (LT 50 ) in more severely stressed animals. The haematocrit value and phagocytic index significantly decreased in HP samples, revealing a detrimental effect on mechanisms of immunological defence. Acid phosphatase and β-glucuronidase activity was also affected by increasing mechanical stress, even though an opposite trend was shown in the two investigated enzymes. Lastly, higher damage levels were detected in shells of HP clams.