A Morphometric Approach to Understand Prokaryoplankton: A Study in the Sicily Channel (Central Mediterranean Sea).

A new understanding of plankton ecology has been obtained by studying the phenotypic traits of free-living prokaryotes in the Sicily Channel (Central Mediterranean Sea), an area characterised by oligotrophic conditions. During three cruises carried out in July 2012, January 2013 and July 2013, the volume and morphology of prokaryotic cells were assessed microscopically using image analysis in relation to environmental conditions. The study found significant differences in cell morphologies among cruises. The largest cell volumes were observed in the July 2012 cruise (0.170 ± 0.156 µm3), and the smallest in the January 2013 cruise (0.060 ± 0.052 µm3). Cell volume was negatively limited by nutrients and positively by salinity. Seven cellular morphotypes were observed among which cocci, rods and coccobacilli were the most abundant. Cocci, although they prevailed numerically, always showed the smallest volumes. Elongated shapes were positively related to temperature. Relationships between cell morphologies and environmental drivers indicated a bottom-up control of the prokaryotic community. The morphology/morphometry-based approach is a useful tool for studying the prokaryotic community in microbial ecology and should be widely applied to marine microbial populations in nature.

Signals from the deep-sea: Genetic structure, morphometric analysis, and ecological implications of Cyclothone braueri (Pisces, Gonostomatidae) early life stages in the Central Mediterranean Sea.

Cyclothone braueri (Stomiiformes, Gonostomatidae) is a widely distributed fish inhabiting the mesopelagic zone of marine tropical and temperate waters. Constituting one of the largest biomasses of the ocean, C. braueri is a key element in most of the ecological processes occurring in the twilight layer. We focused on the ecological processes linked to early life stages in relation to marine pelagic environmental drivers (temperature, salinity, food availability and geostrophic currents) considering different regions of the Central Mediterranean Sea. A multivariate morphometric analysis was carried out using six parameters with the aim of discerning different larval morphotypes, while a fragment of 367 bp representing the 12S ribosomal RNA gene was used to perform molecular analyses aimed at determining the intraspecific genetic variability. Analysis highlighted two geographically distinct morphotypes not genetically discernible and related to the different nutritional conditions due to spatial heterogeneities in terms of temperature and food availability. The body depth (BD) emerged as an appropriate morphometric parameter to detect the larval condition in this species. Molecular analysis highlighted a moderate genetic divergence in the fish population, showing the recurrence of two phylogroups not geographically separated.

Seascape connectivity of European anchovy in the Central Mediterranean Sea revealed by weighted Lagrangian backtracking and bio-energetic modelling.

Ecological connectivity is one of the most important processes that shape marine populations and ecosystems, determining their distribution, persistence, and productivity. Here we use the synergy of Lagrangian back-trajectories, otolith-derived ages of larvae, and satellite-based chlorophyll-a to identify spawning areas of European anchovy from ichthyoplanktonic data, collected in the Strait of Sicily (Central Mediterranean Sea), i.e., the crucial channel in between the European and African continents. We obtain new evidence of ecosystem connectivity between North Africa and recruitment regions off the southern European coasts. We assess this result by using bio-energetic modeling, which predicts species-specific responses to environmental changes by producing quantitative information on functional traits. Our work gives support to a collaborative and harmonized use of Geographical Sub-Areas, currently identified by the General Fisheries Commission for the Mediterranean. It also confirms the need to incorporate climate and environmental variability effects into future marine resources management plans, strategies, and directives.

General surface circulation controls the interannual fluctuations of anchovy stock biomass in the Central Mediterranean Sea.

The sustainable exploitation of small pelagic fish populations, characterized by short life span and early age at first reproduction, is typically more influenced by the success of annual recruitment rather than by fishing mortality. Recruitment strength, in turn, is related to the high environmental variability characterizing the pelagic fish habitats, able to strongly affect the survival of early stages, from hatching to recruitment. Here, we consider the case study of anchovy (Engraulis encrasicolus) stock in the Strait of Sicily (Central Mediterranean). The interannual fluctuations exhibited over an 18-year long period by this fish population was found to be mainly linked to surface circulation patterns, as far as they are able to control retention/dispersal processes of larval stages. We firstly used Lagrangian simulations to reproduce the fate of anchovy early stages during their planktonic phase. Larval retention indices constructed from the output of the simulations were able alone to explain a large proportion of variance (up to 70%) in yearly biomass of the anchovy population, outclassing the other environmental factors considered in this study. Such results are relevant for fisheries management, for all fish stocks characterized by potentially high vulnerability of early life stages.

Benthic-pelagic coupling mediates interactions in Mediterranean mixed fisheries: An ecosystem modeling approach.

Benthic-pelagic coupling plays a pivotal role in aquatic ecosystems but the effects of fishery driven interactions on its functioning has been largely overlooked. Disentangling the benthic-pelagic links including effects of mixed fisheries, however, needs sketching a whole description of ecosystem interactions using quantitative tools. A holistic food web model has been here developed in order to understand the interplay between the benthic-pelagic coupling and mixed fisheries in a Mediterranean system such as the Strait of Sicily. The reconstruction of the food web required review and integration of a vast set of local and regional biological information from bacteria to large pelagic species that were aggregated into 72 functional groups. Fisheries were described by 18 fleet segments resulting from combination of fishing gears and fishing vessel size. The input-output analysis on the food web of energy pathways allowed identifying effects of biological and fishery components. Results showed that the structure of the Strait of Sicily food web is complex. Similarly to other Mediterranean areas, the food web of the Strait of Sicily encompasses 4.5 trophic levels (TLs) with the highest TLs reached by bluefin tuna, swordfish and large hake and largely impacted by bottom trawling and large longline. Importantly, benthic-pelagic coupling is affected by direct and indirect impacts among groups of species, fleets and fleets-species through the whole trophic spectrum of the food web. Moreover, functional groups able to move on large spatial scales or life history of which is spent between shelf and slope domains play a key role in linking subsystems together and mediate interactions in the Mediterranean mixed fisheries.

Distribution of fragrances and PAHs in the surface seawater of the Sicily Channel, Central Mediterranean.

The Mediterranean Sea is highly influenced by several anthropic pressures, including different kinds of organic pollutants. Fragrance Materials (FMs) and Polycyclic Aromatic Hydrocarbons (PAHs) were investigated in the surface seawater of the Sicily Channel in offshore and coastal areas. Total concentrations of FMs and PAHs resulted respectively up to 112ngL-1 and 43ngL-1, with similar distributions of both classes of analytes. Low values were detected in some coastal samples, due to the upwelling of deep and unpolluted waters, while the presence of gyres probably accumulates contaminants in offshore areas. Confirming previous works, the allergenic and oestrogenic Salicylates generally resulted the most abundant FMs and diagnostic ratios indicated combustion processes as the sources of PAHs. The coupling of the well-known PAHs with a new class of Personal Care Products (PCPs) helped the identification of the major environmental drivers: the results highlighted the role of mesoscale hydrodynamics and suggested long-range atmospheric transport as key factors. The first detection of the selected FMs in open sea areas supports the hypothesis of their environmental persistence.

Habitat selection response of small pelagic fish in different environments. Two examples from the oligotrophic Mediterranean Sea.

A number of scientific papers in the last few years singled out the influence of environmental conditions on the spatial distribution of fish species, highlighting the need for the fisheries scientific community to investigate, besides biomass estimates, also the habitat selection of commercially important fish species. The Mediterranean Sea, although generally oligotrophic, is characterized by high habitat variability and represents an ideal study area to investigate the adaptive behavior of small pelagics under different environmental conditions. In this study the habitat selection of European anchovy Engraulis encrasicolus and European sardine Sardina pilchardus is analyzed in two areas of the Mediterranean Sea that largely differentiate in terms of environmental regimes: the Strait of Sicily and the North Aegean Sea. A number of environmental parameters were used to investigate factors influencing anchovy and sardine habitat selection. Acoustic surveys data, collected during the summer period 2002-2010, were used for this purpose. The quotient analysis was used to identify the association between high density values and environmental variables; it was applied to the entire dataset in each area in order to identify similarities or differences in the "mean" spatial behavioral pattern for each species. Principal component analysis was applied to selected environmental variables in order to identify those environmental regimes which drive each of the two ecosystems. The analysis revealed the effect of food availability along with bottom depth selection on the spatial distribution of both species. Furthermore PCA results highlighted that observed selectivity for shallower waters is mainly associated to specific environmental processes that locally increase productivity. The common trends in habitat selection of the two species, as observed in the two regions although they present marked differences in hydrodynamics, seem to be driven by the oligotrophic character of the study areas, highlighting the role of areas where the local environmental regimes meet 'the ocean triad hypothesis'.

Columbus: ready for the International Space Station.

One of the key contributions to the development and operation of the International Space Station (ISS) is ESA's Columbus Laboratory Module. It will be transported to the ISS, together with its payload complement, on Space Shuttle Assembly Flight 1E in 2006. Columbus's readiness for launch requires the availability not only of the Module itself, but also three other major elements being provided by ESA, namely: the Ground Segment, consisting of the Columbus Control Centre and the User Support and Operations Centres (USOCs), the Operations products, and the Crew Training.