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Identification of the potential habitat of European anchovy (Engraulis encrasicolus) at different life stages in relation to environmental conditions is an interesting subject from both ecological and management points of view. For this purpose, acoustic data from different seasons and different parts of the Mediterranean Sea along with satellite environmental and bathymetry data were modelled using generalized additive models. Similarly, egg distribution data from summer ichthyoplankton surveys were used to model potential spawning habitat. Selected models were used to produce maps presenting the probability of anchovy presence (adults, juveniles and eggs) in the entire Mediterranean basin, as a measure of habitat adequacy. Bottom depth and sea surface chlorophyll concentration were the variables found important in all models. Potential anchovy habitats were located over the continental shelf for all life stages examined. An expansion of the potential habitat from the peak spawning (early summer) to the late spawning season (early autumn) was observed. However, the most suitable areas for the presence of anchovy spawners seem to maintain the same size between seasons. Potential juvenile habitats were associated with highly productive inshore waters, being less extended and closer to coast during winter than late autumn. Potential spawning habitat in June and July based on ichthyoplankton surveys overlapped but were wider in extent compared with adult potential habitat from acoustics in the same season. Similarities and dissimilarities between the anchovy habitats as well as comparisons with sardine habitats in the oligotrophic Mediterranean Sea and other ecosystems with higher productivity are discussed

Integrated information from different parts of the Mediterranean Sea was used to model the spatial and temporal variability of the distribution grounds of the sardine population. Acoustic data from the North Aegean Sea (Eastern Mediterranean), the Adriatic Sea (Central Mediterranean), the Sicily Channel (Central Mediterranean) and Spanish Mediterranean waters (Western Mediterranean) were analysed along with satellite environmental and bathymetric data to model the potential habitat of sardine during summer, autumn and early winter. Generalized additive models were applied in a presence−absence approach. Models were validated in terms of their predictive ability and used to construct maps exhibiting the probability of sardine presence throughout the entire Mediterranean basin as a measure of habitat adequacy for sardine. Bottom depth and sea surface temperature were the environmental variables that explained most of the data variability. Several areas along the Mediterranean coastline were indicated as suitable habitat for sardine in different seasons. An expansion of these areas over the continental shelf, up to 100 m depth, was consistently noticed from summer to winter. This was attributed to the horizontal movements of sardine related to spawning (i.e. winter period) and the peculiarities of the Mediterranean Sea where areas favouring growth, feeding and spawning processes tend to be localised and prevent a long range, offshore migration as opposed to large upwelling ecosystems. Moreover, within the study period, a positive relationship between the extent of sardine preferred habitat and landings was revealed for both summer and winter seasons throughout the entire Mediterranean Sea

The spatial stock complexity of marine fish species requires that population structure is taken into account in fisheries management. The aim of this study was to determine whether the amino acid composition (AAC) of the adult fish allows the identification of subpopulations within the stock. During a cruise in November 2003 along the entire Mediterranean coast of Spain, individuals were collected of the following pelagic species: Sardina pilchardus, Sardinella aurita, Engraulis encrasicolus, Trachurus trachurus, Trachurus mediterraneus, Scomber scombrus and Scomber colias. Individuals of S. pilchardus and E. encrasicolus were also collected from the waters of the Strait of Sicily in 2002 and 2003. The AAC of the fish eyes was seen to be species specific, and therefore, the differences in AAC among species may be based on inherited characters. Moreover, a clear differentiation was seen between the Spanish and Sicilian populations of S. pilchardus and E. encrasicolus. Furthermore, in the Spanish waters of the Mediterranean Sea, discriminant analysis revealed a substantial separation between the northern and southern subpopulations of S. pilchardus, S. aurita and E. encrasicolus. Temporal variations in AAC within species in each area were lower than the spatial variations observed among areas for each species, probably reflecting the influence on the AAC of the contrasting environmental characteristics of each area. Our results indicate that the ACC of the eyes in adult fish is a good tool for discriminating among subpopulations in pelagic marine fish species.

It is not clear whether global warming will favour or reduce global ocean phytoplankton productivity in coastal areas. Moreover, the relative contributions made by natural and/or anthropogenic factors to possible changes in phytoplankton productivity are not clear. As the relationship between primary production and alongshore wind forcing is well established for the Eastern Boundary Current (EBC) ecosystems, our aim is to determine whether the changes experienced over the last five decades (1958–2007) in atmospheric CO2 and solar activity have been able to affect the wind regime and water column stability in the most biologically productive upwelling areas of California, Canary, Humboldt and Benguela. We approached the work by statistically studying the effect of solar activity and atmospheric CO2 on surface alongshore wind stress and on water column stability. There was an increasing trend in wind stress and water column stability in all the upwelling areas over the period studied (with the single exception of stability in the California EBC system). The analysis of detrended series evidenced significant relationships between atmospheric CO2 concentration and wind stress and water column stability in the coastal upwelling areas investigated. In addition, wind stress and stability data were found to be consistent, with negative linear relationships between wind stress and CO2 in most of the sites in the Benguela, Canary and Humboldt regions associated, as expected, to positive relationships when water column stability is used as regressand. The results of the present study suggest that greenhouse gas forcing, independent of its well known general increasing trend, was able to decrease wind stress intensity and increase water column stability for the period 1958 to present in most of the sites of the four Eastern Boundary Ecosystems studied, with the one exception of the California region. Conversely, the impact of solar activity appeared to be quite low compared to

It is not clear whether global warming will favour or reduce global ocean phytoplankton productivity in coastal areas. Moreover, the relative contributions made by natural and/or anthropogenic factors to possible changes in phytoplankton productivity are not clear. As the relationship between primary production and alongshore wind forcing is well established for the Eastern Boundary Current (EBC) ecosystems, our aim is to determine whether the changes experienced over the last five decades (1958–2007) in atmospheric CO2 and solar activity have been able to affect the wind regime and water column stability in the most biologically productive upwelling areas of California, Canary, Humboldt and Benguela. We approached the work by statistically studying the effect of solar activity and atmospheric CO2 on surface alongshore wind stress and on water column stability. There was an increasing trend in wind stress and water column stability in all the upwelling areas over the period studied (with the single exception of stability in the California EBC system). The analysis of detrended series evidenced significant relationships between atmospheric CO2 concentration and wind stress and water column stability in the coastal upwelling areas investigated. In addition, wind stress and stability data were found to be consistent, with negative linear relationships between wind stress and CO2 in most of the sites in the Benguela, Canary and Humboldt regions associated, as expected, to positive relationships when water column stability is used as regressand. The results of the present study suggest that greenhouse gas forcing, independent of its well known general increasing trend, was able to decrease wind stress intensity and increase water column stability for the period 1958 to present in most of the sites of the four Eastern Boundary Ecosystems studied, with the one exception of the California region. Conversely, the impact of solar activity appeared to be quite low compared to

The aim of this study was to identify the factors responsible for the differences in chlorophyll a concentration (Chl-a) observed between the California, Canary, Humboldt and Benguela upwelling areas. Monthly climatologic values of Chl-a obtained from satellite images, covering the years 1998–2004, revealed that this pigment was higher in the Benguela system than in the other areas. Upwelling intensity, as derived from offshore Ekman transport computations, was higher in the Benguela and Humboldt regions and, for the same upwelling intensity, Chl-a was higher in Benguela than in the other regions. Upwelling intensity appears to be able to drive Chl-a densities through nutrient supply, as nutrients are correlated to offshore Ekman transport. A linear regression model including the fraction of sea surface over the shelf in each 1° × 1° box, nitrate, silicate, turbulence and variability of offshore Ekman transport explained the 84.8% of the variance in Chl-a among the areas. Differences in offshore Ekman transport explained the lower Chl-a observed in Canary and California and the higher Chl-a observed in Benguela and Peru-Humboldt. A narrow continental shelf and low water column stability also contribute to reducing phytoplankton pigment biomass in the Canary and California areas. The higher Chl-a values observed in Benguela compared to Humboldt-Peru are due to a wider extension of the continental shelf in the Benguela region.

Egg and larval abundance, obtained from annual summer cruises carried out in the Strait of Sicily during 6 years (1997 to 2002), was used to identify the spawning and retention areas of the anchovy Engraulis encrasicolus. Larval amino acid composition was used to analyse the nutritional condition of the larvae collected during the 2002 survey. As the anchovy spawns along the south Sicilian coast, but mainly in the north-west and middle parts of the coast, the higher number and larger size larvae in the south-east end of the Sicilian coast indicated that larvae were transported by the main branch of the Atlantic-Ionian Stream and retained in the south-east end of the Sicilian coast (Cape Passero). This retention process, however, did not always favour the nutritional condition of the larvae, because the larvae were not transported to an area with a higher primary production or with a higher stability. In 2002 larval amino acid concentration was higher in the spawning areas than in those areas where the larvae were transported to, indicating a lower nutritional condition of the larvae in the nursery areas. The lack of enrichment and concentration processes, and low primary production in this area which limited body growth rate may explain the low locally reproducing anchovy population in the south coast of Sicily.