Seafloor integrity down the harbor waterfront: the coralligenous shoals off Vado Ligure (NW Mediterranean)

In the last ten years, European Directives stressed the necessity to assess the ecological status of marine habitats by means of ecosystem or landscape indicators, rather than just species or chemical ones. In this paper, the seascape approach to characterise and assess the ecological quality of coralligenous rocky shoals of Vado Ligure (Savona, Italy) is introduced. This approach integrates biological, mesological and geomorphological information collected with a Rapid Visual Assessment technique (RVA). The RVA also optimised underwater operations in deep waters where coralligenous reefs usually develop and provided a sufficient amount of data collected by direct inspection. The seascape approach results are appropriate for the characterisation of the coralligenous shoals studied and for the assessment of their ecological quality. The quality of the assemblages was in general low, mainly due to high sedimentary stress; however, some exceptions showing a high ecological quality indicate that, with proper manage- ment tools, they would still have good potentialities of recovery

Life-history traits of the bivalve Spisula subtruncata (da Costa) in the Ligurian Sea (North-Western Mediterranean): The contribution of newly settled juveniles

A population of Spisula subtruncata was studied in four different years (1983-1984; 1990-1993) on a shallow sandy bottom in the Ligurian Sea. Throughout the studied period, the S. subtruncata population was characterised by wide seasonal and interannual fluctuations both in abundance and biomass. Its life-cycle was normally annual, and there was an almost complete disappearance of the bivalve during winter months. The population of Spisula subtruncata was characterised by the dominance of juvenile forms and very few adults (maximum total length observed, 13 mm). Population size varied according to recruitment success. In the 1 mm samples, Spisula was particularly abundant within the community during the spring-summer period of 1991, with peaks of density and biomass of 1017 individuals m-2 (\uc2\ub1 30.9 std) and 114.5 mg AFDW m-2 in May. From January 1991 to February 1993 the juvenile density of the bivalve was measured in meiofaunal samples. Juveniles were characterised by wide seasonal fluctuations, with density peaks in May (10,350 individuals m-2 \uc2\ub1 248 and 11,403 individuals m-2 \uc2\ub1 378, in 1991 and 1992, respectively). A mortality rate higher than 90% was estimated (measured as the difference between the density peak of juveniles and the density of the following peak of adults). Production was 0.58 (1983-84), 0.44 (1991-92) and 0.12 g m-2 yr-1 (1992-93). Considering also the contribution of temporary meiofauna, secondary production raised up to 0.52 in 1991-1992; and to 0.18 g m-2 yr-1 in 1992-93. The year 1990 was characterised by very low density so that no production value was estimated. A number of features are discussed: the variability observed in the demographic structure of the bivalve with the latitudinal gradient; the relation between population structure and production values; and the contribution of the smallest size classes to energy flow

Stressors affecting the macrobenthic community in Rapallo Harbour (Ligurian Sea, Italy)

An annual survey was carried out in Rapallo Harbour (Ligurian Sea, NW Mediterranean) to study the main stressors affecting the macrobenthic communities. The harbour was characterised by a relevant organic enrichment (between 51.9 mg g\u20131 and 109.6 mg g\u20131), which did not affect the water column oxygenation, and low but detectable heavy-metal contamination (on average Cu=135.0 \u3bcg g\u20131 and V=23.8 \u3bcg g\u20131). The seasonal changes in the heavy metal concentrations suggested a significant increase in tourist activities (i.e. boat movements) during summer and autumn. In the inner, more protected sampling site, the harbour structures and the vessel movements increased both organic enrichment and sediment instability, resulting in macrobenthic communities dominated by indicator species associated with these stressors. In addition, during summer and autumn, despite a relevant chlorophyll-a flux to the sediment, the settling material was dominated by phaeopigments and refractory proteins, which reduced its trophic value for benthic consumers. In the outer part of the harbour the main stressor was a polluted freshwater inflow, as indicated by the dominance of indicator species such as Capitella spp. (on average 79.5%), Neanthes caudata, Malacoceros girardi and Diopatra neapolitana

The use of otolith microchemistry to investigate spawning patterns of European anchovy: A case study in the eastern Ligurian Sea (NW Mediterranean)

Spawning patterns of European anchovy were investigated in the eastern Ligurian Sea (NW Mediterranean) by using otolith microchemistry. Otolith cores of 1-year-old anchovies showed a homogeneous chemical composition, while those of 2 years old anchovies separated into five different groups. This suggests the occurrence of single vs. multiple spawning areas related to the two annual cohorts. Patterns of core microchemistry of 2 years old anchovies support the hypothesis of different spawning areas, possibly characterised by different salinity regimes, in the eastern Ligurian Sea (e.g. typical marine habitats like shelf edges vs. lower salinity locations like river mouths). Results suggest that: (1) stocks of European anchovy could depend on different spawning areas characterised by different environmental conditions; (2) patterns may change from year to year, and this could affect the annual risk of stock fluctuations or collapse; and (3) the use of otolith microchemistry is a promising approach for investigating spawning patterns of European anchovy. © 2012 Elsevier B.V