Could feeding habit and migratory behaviour be the causes of different toxicological hazard to cetaceans of Gulf of California (Mexico)?

In this work, a suite of diagnostic biomarkers was applied to seven cetacean species to evaluate the role of the feeding habits and migratory behavior in the toxicological status of these species from the Gulf of California, Mexico. We investigate the interspecific differences in cytochrome P450 1A1 and 2B (CYP1A1 and CYP2B, respectively), aryl hydrocarbon receptor and E2F transcription factor 1 and the contaminants levels [organochlorine compounds, polybrominated diphenyl ethers (PBDEs) and polycyclic aromatic hydrocarbons (PAHs)] in four odontocete species (common bottlenose dolphin, long-beaked common dolphin, sperm whale and killer whale) and three mysticete species (blue whale, fin whale, and Bryde's whale) using skin biopsy. Differences in contaminant levels and molecular biomarker responses between the odontocete and mysticete species have been pointed out. The canonical discriminant analysis on principal component analysis factors, performed to reveal clustering variables, shows that odontocete are characterised by the highest levels of lipophilic contaminants compared to the mysticete, with the highest levels of polychlorinated biphenyls, dichlorodiphenyltrichloroethanes and PBDEs detected in killer whale and the lowest levels in Bryde's whale. The biomarker data show interspecific differences amongst the seven species, revealing highest CYP1A and CYP2B protein levels in the mysticete fish-eating species (Bryde's whale). In conclusion, three main factors seem to regulate the biomarker responses in these species: (a) the inductive ability of persistent organic pollutants and PAHs; (b) the different evolutionary process of the two CYPs related to the different feeding habits of the species; (c) the migratory/resident behaviour of the mysticete species in this area.

Temporal variations in the diet of pearly razorfish Xyrichtys novacula (Osteichthyes: Labridae).

The diet of pearly razorfish Xyrichtys novacula, caught monthly along the shores of the Island of Lampedusa, appeared to be mainly composed of crustaceans, followed by colonial ascidians, molluscs and polychaetes. Among prey, sand dwellers and phanerogam-associated species were recorded. In winter months, the diet was characterized by a small number of prey items, dominated by colonial ascidians, while in spring and summer a wider prey array was recorded. Dietary indices show that X. novacula do not strictly exploit benthic prey but also pelagic organisms, such as copepods. This feeding behaviour reached its peak in March and October, when the abundance of primary consumers was at its highest after phytoplankton blooms. Furthermore, X. novacula caught prey organisms according to their availability and seasonal patterns during their life cycles, irrespective of fish size.

Metal content and toxicity of produced formation water (PFW): study of the possible effects of the discharge on marine environment.

A preliminary chemical and ecotoxicological assessment was performed on the produced formation water (PFW) and superficial sediment around a gas platform (Fratello Cluster), located in the Adriatic Sea (Italy), in order to evaluate the effects of PFW discharged from the installation. The ecotoxicological bioassays, with the marine bacterium Vibrio fischeri and the sea urchin Paracentrotus lividus, were associated with chemical data to estimate the possible effects on living organisms. PFW collected on the platform was toxic, but no significant effect was recorded on marine sediment. Only the sediment station nearest to the discharge point showed higher values of some contaminants (zinc and arsenic) in comparison to other sites and only some stations showed low toxicity.

Short- and long-term effects of a dietary yeast beta-glucan (Macrogard) and alginic acid (Ergosan) preparation on immune response in sea bass (Dicentrarchus labrax).

The present study investigated the immunomodulatory activity of Ergosan, an algal extract containing alginic acid, and Macrogard, a yeast extract containing beta-glucans, on innate and specific immunity in sea bass (Dicentrarchus labrax). Four cycles of experimental feeding using normal fish feed formulation (control group) supplemented with Ergosan (0.5%) or Macrogard (0.1%) were performed at 60-day intervals (15 days of treatment+45 days of suspension). Serum complement, lysozyme, total proteins and heat shock protein (HSP) concentrations were measured at 15, 30 and 45 days from the end of the first 15-day feeding cycle (short term) and 45 days after the end of each feeding cycle over a 35-week period (long term). The percentage of B- and T-lymphocytes in peripheral blood leucocytes and gut were measured over long-term trial. Significant elevation (P < 0.05) in serum complement activity occurred in sea bass fed with alginic acid and glucans, at 15 days from the end of first cycle of treatment. Significant elevation (P < 0.05) in serum lysozyme, gill and liver HSP concentration were observed in the same experimental groups at 30 days from the end of treatment, whereas a significant increase (P < 0.05) of complement activity was only observed in fish that received an Ergosan diet. At 45 days from the end of treatment, complement, lysozyme and HSP concentration did not differ among groups. Over the long-term period, no significant differences were observed in innate and specific immune parameters, survival, growth performances and conversion index in treated and control fish. A dramatic decrease of both innate and acquired immune parameters was observed during the winter season in all groups, followed by a partial recovery when water temperature increased. Reduction in complement and lysozyme activities was significatively correlated (p < 0.01) to water temperature variation. The results suggested the potential of alginic acid and beta-glucans to activate some innate immune responses in sea bass, and particularly under conditions of immunodepression related to environmental stress.