Mario Petrillo

The Ligurian Sea: present status, problems and perspectives

The Ligurian Sea is a deep basin in the northernmost sector of the western Mediterranean which shows peculiar hydrodynamic and meteo-oceanographic features. The coasts of the Ligurian Sea are among the most urbanised and industrialised along the Italian coastline: the main causes of disturbance being littoral urban development and harbour activities, the building of littoral rail- and highways, and the presence of several polluted discharges. This review, by evaluating the huge scientific output published in the last three decades, describes and discusses the most important geological, hydrological and biological characteristics of the Ligurian Sea. We show that this regional sea has largely been investigated in terms of its geological and structural evolution, as well as in terms of the sedimentation dynamics of the littoral and deep bottoms, with particular attention to the sedimentation balance of the beaches and their erosive processes. We report that the prevalent hydrodynamic and meteo-oceanographic conditions favour a continuous exchange of coastal water masses, and that the seasonal and interannual dynamics of water masses can effects the local climate, with direct and indirect consequences on fish and benthic communities documented in the last decade. We stress that although recent studies offer good knowledge of the distribution of coastal benthic communities, only scant information is available for the whole continental shelf, the submarine canyons and the rocky bathyal bottoms. Our meta-analysis reveals that significant fishing activities are monitored, but also that certain sectors of the biological resource are suffering, and suggests the set up of appropriate management measures. The Ligurian Sea hosts a number of Marine Protected Areas (MPAs) of high relevance, while the institution of the Whale Sanctuary completes the protection policy of the Regione Liguria. Our meta-analysis points out the need for long-term studies, based primarily on the analysis of those areas of the Ligurian Sea that have been little investigated to date. Finally, only properly addressed studies, using experimental approaches and along appropriate spatial and temporal scales, might allow us to understand the functioning of the Ligurian marine ecosystems, evaluate their health conditions and the dynamics of the main variables that affect the distribution of the single species (including species of high economic value) and benthic communities.

Population structure of the necrophagous amphipod Eurythenes gryllus (Amphipoda: Gammaridea) from the Atacama Trench (south-east Pacific Ocean)

Baited traps deployed at 7800 m in the Atacama Trench off northern Chile, captured over 400 specimens of Eurythenes gryllus. This is the greatest depth of occurrence reported for the species. Of the 398 specimens available for study, all but three were female, giving a sex ratio very different from any reported previously. Female specimens measured 29–76 mm in length, and all were immature. Length/frequency distributions based on total length, peraeonite 1 length, and coxa 4 oostegite length were unimodal. Relationships between total length, and peraeonite 1 length, oostegite length, and wet weight were established. Oostegite development appeared to be precocious compared with published data. Subtle differences in peraeon, urosome, gnathopods, coxa 4, peraeopod 7, and epimeron 3 morphology, and the growth of oostegites separate Atacama Trench specimens from previously described material. The morphology exhibited by these specimens lies outside the known variability of E. gryllus , and suggests that this pan-oceanic entity may be undergoing incipient speciation.

Community experiments using benthic chambers : Microbial significance in highly organic enriched sediments

Abstract The structure of the benthic microbial loop was studied in order to understand heterotrophic pathways in the suboxic sediments of the Rapallo Harbour in autumn, 1996. Sediments were characterized by the large accumulation of organic detritus (17.2 – 21.4 μg chloroplastic pigment equivalents (CPE)g−1; carbohydrates and proteins: 7.8–16.7 and 6.7–7.5 mg g−1). Due to the high organic load, benthic bacteria and protozoa displayed extremely high densities (1.4 × 109 cells g−1 and 26.9 × 105 cells g−1). Meiofauna, protozoa and bacteria showed an approximate biomass ratio of 1:2:20. the presence of large amounts of organic matter appeared to determine a shift of the benthic size structure toward the increasing dominance of the smaller components of the benthic food webs. These data indicate that the sediments of the Rapallo Harbour were dominated by microbial biomasses to a larger extent than in non-food limited environments, characterized by a lower organic contamination. On the results presented in th...

Intertidal benthic communities of two Chilean coastal islands (Santa María and Mocha, Southeastern Pacific)

Six macrotidal beaches located on two Chilean coastal islands (Santa María and Mocha, SE Pacific Ocean) were investigated in spring 2001 (29 October–3 November) to verify the role of the food supply (in terms of quantity and biochemical composition of the organic matter) on the abundance and diversity of the macro- and meiobenthic communities inhabiting the beaches. Samples of sediment were collected from the intertidal zone of the three beaches of each island investigated. The total organic matter content of the sediment did not differ between the islands, whereas the phytopigment and protein contents were significantly higher on Mocha (2.3±0.9 and 75±21 μ g g−1, mean values of the three beaches±SE, respectively) than on Santa María (0.5±0.2 and 50±16 μ g g−1, mean values of the three beaches±SE). The macro- and meiofaunal assemblages displayed the highest abundances on Mocha (821±223 and 561±194 ind. 10 cm−2, respectively). The abundance of both assemblages was correlated with the quality of the food supply, and significant correlations were observed with the phytopigment content (Spearman-rank R=0.645 p<0.01 and R=0.934 p<0.001 for the macro- and meiofauna, respectively). The results of the present study suggest that food availability may play a key role in structuring benthic communities of the oceanic beaches of Chilean coastal islands. A single observation is not enough to fully understand the real mechanisms that shape the beach communities, however, the snapshot image we collected during this study suggests that the role of food availability in shaping benthic beach communities may be as important as that played by the hydrodynamic conditions.

Zooplankton in the surrounding waters of the Juan Fernández Archipelago

Un estudio para el conocimiento de los estadios larvales de Jasus frontalis (Milne-Edwards, 1836) ha permitido estimar la composicion cualitativa y la estructura cuantitativa del zooplancton en las aguas del archipielago Juan Fernandez.