Mitochondrial DNA reveals a mosaic pattern of phylogeographical structure in Atlantic and Mediterranean populations of anchovy (Engraulis encrasicolus)

This study extends the geographic coverage of a previous study of mitochondrial DNA restriction fragment length polymorphism in European anchovy. Both studies together include 24 samples representing 17 localities extending from the Black Sea, through the Mediterranean Sea to the eastern Atlantic as far south as Dakar, Senegal. Eighty-eight haplotypes define two clades (A and B) separated by 3.2% sequence divergence. Clade A has a star-like genealogy indicative of a recent population expansion. Clade B has a more complex genealogy, consisting of several haplotypes at intermediate frequencies. The distributions of these clades consist of a mosaic with abrupt changes between some areas and gradients between other areas. Clade A predominates the Black and Aegean seas, but is present throughout the Mediterranean. Unexpectedly, new data show that clade A is also at a high frequency in the Atlantic, from Portugal to at least Senegal. Overall, the level of genetic differentiation among populations is high (F(ST)=0.148, p<0.0001), with the greatest differences between basins. AMOVA reveals four main geographical groups: Atlantic, central Mediterranean, Aegean Sea, and Black Sea. Mismatch distribution clearly indicates historical bottleneck and population expansion for clade A, while for clade B such evidence is equivocal. This difference may reflect a range expansion for both clades, but with higher gene flow (Nm values) between demes for clade A. Both contemporary and historical processes are important in shaping the complex genetic population structure of European anchovy.     

Energy density of anchovy Engraulis encrasicolus in the Bay of Biscay

The energy density ( E _D) of anchovy Engraulis encrasicolus in the Bay of Biscay was determined by direct calorimetry and its evolution with size, age and season was investigated. The water content and energy density varied seasonally following opposite trends. The E _D g⁻¹ of wet mass ( M _W) was highest at the end of the feeding season (autumn: c . 8 kJ g⁻¹ M _W) and lowest in late winter ( c . 6 kJ g⁻¹ M _W). In winter, the fish lost mass, which was partially replaced by water, and the energy density decreased. These variations in water content and organic matter content may have implications on the buoyancy of the fish. The water content was the major driver of the energy density variations for a M _W basis. A significant linear relationship was established between E _D g⁻¹ ( y ) and the per cent dry mass ( M _D; x ): y =−4·937 + 0·411 x . In the light of the current literature, this relationship seemed to be not only species specific but also ecosystem specific. Calibration and validation of fish bioenergetics models require energy content measurements on fish samples collected at sea. The present study provides a first reference for the energetics of E. encrasicolus in the Bay of Biscay.     

Genetic structuring of European anchovy (Engraulis encrasicolus) populations through mitochondrial DNA sequences

Mitochondrial DNA sequence variation in 655?bpfragments of the cytochrome oxidase c subunit I gene, known as the DNA barcode, of European anchovy (Engraulis encrasicolus) was evaluated by analyzing 1529 individuals representing 16 populations from the Black Sea, through the Marmara Sea and the Aegean Sea to the Mediterranean Sea. A total of 19 (2.9%) variable sites were found among individuals, and these defined 10 genetically diverged populations with an overall mean distance of 1.2%. The highest nucleotide divergence was found between samples of eastern Mediterranean and northern Aegean (2.2%). Evolutionary history analysis among 16 populations clustered the Mediterranean Sea clades in one main branch and the other clades in another branch. Diverging pattern of the European anchovy populations correlated with geographic dispersion supports the genetic structuring through the Black Sea-Marmara Sea-Aegean Sea-Mediterranean Sea quad.     

The North Atlantic Oscillation affects the quality of Cava (Spanish sparkling wine)

This study explores the possible effects of the North Atlantic Oscillation (NAO) on the quality of Spanish Cava. We found a significant negative relationship between the mean NAO for the months of March through August of each year between 1970 and 2008 and the probability of obtaining a top quality Cava. The NAO is associated with temperature and rainfall variations in the Cava region, which affect vine physiological processes during grape maturity. The probability of obtaining a top quality Cava was highest when the mean value of the NAO was negative, which causes the mean temperature in the Cava area to decrease, with positive consequences on Cava quality. Although the overall discrimination capacity and explanatory power of the model were low, 80 % of clearly favorable years were classified correctly as corresponding to top quality Cava, and 70 % of clearly unfavorable years were classified correctly as non top quality Cava.     

Energy density of anchovy Engraulis encrasicolus L. in the Adriatic Sea

European anchovy Engraulis encrasicolus , with total lengths ranging from 40·0 to 132·5 mm, were sampled during October 2002 and May 2003 in the northern Adriatic Sea in order to estimate their energy densities ( E _D). A highly significant ( P  < 0·001) relationship between E _D(y)(J g⁻¹wet mass) and per cent dry mass ( x ) was found: y  = 321 x  − 3316·9 ( n  = 161, r ² = 0·82).     

Genetic differentiation of European anchovy (Engraulis encrasicolus) along the Moroccan coast reveals a phylogeographic break around the 25th parallel North

Seven microsatellite markers were used to investigate the population structure of the offshore ecotype of the European anchovy (Engraulis encrasicolus) by comparing 12 marine samples collected off the Moroccan coast with an inshore sample taken as a reference for the lagoonal ecotype. F-statistics, correspondence analysis and Bayesian assignment all concurred to cluster the European anchovy in this region into three groups: (i) one reference lagoonal sample, (ii) samples north of the 25°N latitude and (iii) samples south of it. Moreover, the Bayesian cluster analysis pointed toward the existence of an admixture between the group north of 25°N and the lagoonal ecotype, while this was not detectable with the group south of 25°N. Differential introgression between the two ecotypes could be one of the plausible explanations for the observed genetic structure and reveals the possible existence of a phylogeographic break around the 25th parallel North. Our study illustrates the fact that, for those species that encompass several incompletely isolated ecotypes, the level of gene flow among them may vary in space and serve as a tool for stock identification. This information may be useful to improve fishery management of this important harvested species along the Moroccan coast.     

Allozyme, mitochondrial-DNA, and morphometrie variability indicate cryptic species of anchovy (Engraulis encrasicolus)

Previous surveys of population structure in the Atlantic-Mediterranean anchovy Engraulis encrasicolus L. have reported heterogeneity in morphology, allozyme frequencies, and mitochondrial DNA haplotype frequencies at a regional scale. In particular, two stocks of anchovy have been detected in the Adriatic Sea. In this paper, the available data is reviewed with the aim to relate genetic variation to geography at the widest possible geographical scale, for investigating the evolutionary mechanisms underlying stock structure in anchovy. Correspondence analysis of allozyme frequencies (24 samples, three polymorphic loci) compiled from the literature indicates three distinct entities in the Mediterranean Sea. Open-sea or oceanic anchovy populations are genetically different from inshore-water populations within a region (Nei's ^ G _ST = 0.035–0.067), while broadscale geographical variation is weak for each of these two habitat-specific forms (^ G _ST = 0.005–0.006). Mitochondrial-DNA haplotype frequencies support the distinction between an inshore form and an oceanic form (^ G _ST = 0.067–0.107), with virtually no genetic differences among oceanic populations across the Gulf of Biscay, the western Mediterranean and the Ionian Sea (^ G _ST = −0.001). If natural selection on marker loci is unimportant, these results indicate the occurrence of two parapatric, genetically distinct, habitat-specific forms that are widely distributed throughout the Mediterranean Sea. Persistent allele and haplotype-frequency differences between these forms indicate reproductive isolation and the presence of an E. encrasicolus species complex in the Mediterranean. © 2002 The Linnean Society of London, Biological Journal of the Linnean Society 75 : 261–269.     

New polymorphic microsatellite loci for population studies in the European anchovy, Engraulis encrasicolus (L.)

Eleven microsatellite loci were developed in the European anchovy, Engraulis encrasicolus, and tested in samples from two geographically distant populations (Atlantic and Mediterranean Sea). Number of alleles ranged from eight to 28 and observed heterozygosity from 0.440 to 0.920. There was no evidence of linkage disequilibrium, although two loci are indeed linked. All loci were in Hardy-Weinberg equilibrium, except for one locus in the Atlantic and two loci in the Mediterranean sample. These three loci plus two more showed evidence for null alleles.     

Field mortality estimates of anchovy larvae, Engraulis encrasicolus, in the western Mediterranean

Eggs and larvae of anchovy were obtained from plankton collections made along the Catalan coast (north-western Mediterranean) from 1983 to 1985 in order to determine spawning seasons and areas and other aspects of its life history. Previous studies have shown the existence of two main spawning areas, to the north and south of the Catalan coast, respectively. The northern one is characterized by a shorter spawning period related with the thermal cycle.
Mortality rates of larvae aged 4.9-15 days were calculated from the peak spawning month (June) of the three years, separately by spawning areas. Data on abundance by length classes were adjusted for escape and net avoidance and for duration of growth through a size class as derived from otolith readings. Mortality rates ranged from 0.17 to 0.58. Mortality was higher in 1983 than in 1984 and 1985, coinciding with a high production of anchovy eggs in that year. Mortality at the northern spawning area was lower than at the southern one.     

Lipid biomarkers and trophic linkages between phytoplankton, zooplankton and anchovy (Engraulis encrasicolus) larvae in the NW Mediterranean

Identification and quantification of the main fatty acids inphytoplankton, zooplankton and Engraulis encrasicolus larvaewere used to study the relationship among the different trophiclevels. Three northwestern Mediterranean sea areas were studiedas representative of potentially heterogeneous environments.HPLC pigment analysis was performed to assess the contributionof different phytoplankton groups to total chlorophyll biomass.In spite of the physical variability, a homogeneous patternin phytoplankton composition among areas was found, with thePrymnesiophyceae representing more than half of the phytoplanktonchlorophyll biomass. This homogeneous spatial pattern was alsoreflected in the phytoplankton fatty acid proportions. Thus,significant amount of 14:0, 18:1(n-9) and 18:4(n-3) could berelated to the dominance of the prymnesiophytes; the low proportionof fatty acid markers of diatoms and dinoflagellates agreedwith the low abundances of those phytoplankton groups. Zooplanktonfatty acids also showed homogeneous proportions in the studiedareas, with a preferential accumulation of 16:1(n-7) and 20:5(n-3),and 22:6(n-3). This observation may indicate a preferentialgrazing on diatoms and dinoflagellates. Anchovy larvae displayeddiffering fatty acids contributions related to size. Large larvaecontained a higher proportion of polyunsaturated fatty acid(PUFA). Small larvae showed a high percentage of 18:1(n-9) and18:4(n-3) fatty acids, considered Prymnesiophyceae biomarkers.These results suggest an additional food resource for the anchovythat is complementary to a zooplankton diet, but probably ofprotozoan origin (i.e. microzooplankton). Significant logarithmicrelationships were found between dry mass and 20:5(n-3) and22:6(n-3) fatty acid proportions in E. encrasicolus larvae.These PUFA are considered essential for the fish-larvae development.     

Binding kinetics and sequencing of hepatic alpha1-adrenergic receptors in two marine teleosts, mackerel (Scomber scombrus) and anchovy (Engraulis encrasicolus)

Liver alpha(1)-adrenoceptors (ARs) are demonstrated, or at least hypothesized, in freshwater and brackish-water teleosts, whereas no data are available for marine teleosts. This study evaluates the presence of alpha(1)-ARs in the liver of two marine teleosts, the anchovy Engraulis encrasicolus and the mackerel Scomber scombrus, and examines on a broad scale the possibility that habitats posing different challenges also influence phenotypic trait selection. Binding assays were performed also on liver membranes from the carp Cyprinus carpio as a direct comparison with a freshwater species. Scatchard analysis of [(3)H]prazosin binding to purified liver membranes from anchovy, mackerel and carp resulted in K(d) values of 1.51+/-0.085, 1.26+/-0.098, and 2.61+/-0.22 nM, and B(max) values of 87.4+/-9.12, 77+/-8.29, and 115.22+/-3.31 fmol/mg protein, respectively. Thus, alpha(1)-ARs of the two marine teleosts showed higher [(3)H]prazosin affinity compared with those of the freshwater/brackish-water fish studied thus far, whereas the number of liver binding sites did not differ significantly from that of carp, eel or trout. A preliminary phylogeny based on amino acid sequence analysis indicated the presence of at least an alpha(1A)-AR in mackerel and an alpha(1D)-AR in both anchovy and mackerel. This is the first indication of alpha(1)-AR subtypes in any marine species, but further studies are needed to ascertain the physiological role of these alpha(1)-ARs in these two marine species.     

Growth and length–weight relationship of the juvenile anchovy, Engraulis encrasicolus, in the nursery ground (Zrmanja River estuary–eastern Adriatic Sea)

Growth and length–weight relationships of 2564 juvenile specimens of anchovy, Engraulis encrasicolus (Linnaeus, 1758), were examined over a 2‐year period (August 1989 to April 1991) in the Zrmanja River estuary. Fish sizes ranged from 4.4 to 12.5 cm total length and 0.5 and 13.8 g, corresponding to age (in years) 0+ (98%) and 1+ (2%). Length–weight regression coefficient (b) varied between 2.95 and 3.42 and the regression constant (a) between 2.1 and 6.0 (×10^?3). The von Bertalanffy growth equation of juvenile anchovy was: l_t = 13.2 (1 ? e^?0.82(t+0.5)). Maturity was reached in June in males above 8.2 cm and females above 9.0 cm total length.     

'SSW to NNE'– North Atlantic Oscillation affects the progress of seasons across Europe

Three European plant phenological network datasets were analysed for latitudinal and longitudinal gradients of nine phenological ‘seasons’ spanning the entire year. The networks were: (1) the historical first European Phenological Network (1882–1941) by Hoffmann & Ihne, (2) the network of the International Phenological Gardens in Europe (1959–1998), founded by Schnelle & Volkert in 1957 and based on cloned plants, and (3) a dataset (1951–1998) that was recently collated during the EU Fifth Framework project POSITIVE, which included network data of seven Central and Eastern European countries. Our study is most likely the first, for over a century, to analyse average onset and year‐to‐year variability of the progress of seasons across a continent. For early, mid, and late spring seasons we found a marked progress of the seasonal onset from SW to NE throughout Europe, more precisely from WSW to ENE in early spring, then from SW to NE and finally from SSW to NNE in late spring, as exhibited by the relationship between latitudinal and longitudinal gradients. The movement of summer was more south to north directed, as the longitudinal gradient (west–east component) strongly declined or was even of opposite sign. Autumn, as shown by leaf colouring dates, arrived from NE to SW. Possible reasons for the differences among the three datasets are discussed. The annual variability of latitudinal and longitudinal gradients of the seasons across Europe was closely related to the North Atlantic Oscillation (NAO) index; in years with high NAO in both winter and spring, the west–east component of progress was more pronounced; in summer and autumn, the pattern of the seasons may be more uniform.     

Influence of environmental variability on anchovy early life stages (Engraulis encrasicolus) in two different areas of the Central Mediterranean Sea

The survival of early stages of small pelagic fish species (e.g. Engraulis encrasicolus) is highly dependent on environmental conditions in both spawning and nursery areas. Knowing the relationship between the mortality rates of the early stages and the environment may help to study and model recruitment fluctuations. During the summer of 2006, two consecutive oceanographic cruises were carried out in the Central Mediterranean sea (CMED) in two different areas: the western Libyan waters and the Sicilian?CMaltese waters. For the first time a nearly synoptic comparison between the two border areas of the CMED is performed. In spite of a higher overall egg density in the Sicilian?CMaltese waters, there was a higher density of anchovy larvae in Libyan waters. The comparison between the oceanographic datasets singled out different circulation patterns and different characteristics of water masses, which helped to explain the differences in density of the spawning products in the two areas. A Lagrangian transport model was used to evaluate the effects of major oceanographic features on offshore egg and larval transport. The results of the model simulations and the nutritional conditions, as indicated by lipid, carbohydrate and protein contents, support the hypothesis that the western Libyan waters may represent a more favourable nursery ground compared to the Sicilian?CMaltese waters in terms of environmental conditions and food availability.     

Meteorological and climatic variability influences anthropogenic microparticle content in the stomach of the European anchovy Engraulis encrasicolus

Hydrobiologia - Meteorological and climatic phenomena affect oceanographic characteristics and, consequently, anthropogenic microparticle aggregation. The same phenomena influence the ecology of...     

Factors structuring reproductive habitat suitability of Engraulis encrasicolus in the south coast of Sicily

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.     

Interannual variability and intraannual stability of the otolith shape in European anchovy Engraulis encrasicolus (L.) in the Bay of Biscay

In this study 1047 samples of European anchovy Engraulis encrasicolus caught in 2001, 2002 and 2003 in different areas of the Bay of Biscay were examined using otolith shape analysis. For the years 2001 and 2003, 1 year-old individuals were dominant, whereas for the year 2002 they were less common; in contrast 2 year-old individuals represented 74% of the total individuals, suggesting that the fisheries in 2002 were mainly supported by the strong recruitment of 2000. The classification success of the discriminant analysis indicated a strong separation between year groups ( P < 0·001), overall, 98% of individuals were correctly classified. Results from both jackknife and Cohen's kappa procedures confirmed the high rates of classification success obtained by the discriminant analysis (99 and 97%, respectively). Stability in the intraannual shape analysis leads to the idea that individuals were affected by the same intraannual environmental conditions in the Bay of Biscay. Variability in the interannual shape analysis could indicate that the spawning population is composed of European anchovy from different origins every year. In general differences observed suggested that the European anchovy in the Bay of Biscay were members of three or more different communities or entities.     

Mitochondrial DNA phylogeny and the reconstruction of the population history of a species: the case of the European anchovy (Engraulis encrasicolus)

Analysis of mitochondrial DNA restriction fragment length polymorphism in European anchovy (Engraulis encrasicolus) revealed a large number of mitotypes that form two distinct clusters (phylads). Phylad A consists of one common mitotype and many rare secondary mitotypes that are one mutational step removed from the main type. Nucleotide diversity and number of homoplasious changes are low. Phylad B has a complex pattern of mitotype connectedness, high nucleotide diversity, and a large number of homoplasious changes. It is suggested that the two phylads evolved in isolation from each other and that present coexistence is the result of a secondary contact. Moreover, phylad A has a "star" phylogeny, which suggests that it has evolved in a population that experienced a drastic bottleneck followed by an explosion of size. Phylad A is practically the only phylad present in the Black Sea, with its frequency dropping to 85% in the northern Aegean, and to 40% in the rest of Mediterranean and the Bay of Biscay. The Black Sea is, therefore, the most likely place of origin of phylad A. Molecular data are consistent with a population bottleneck in the Black Sea during the last glaciation event and a subsequent exit of phylad A with the outflow into the Aegean following the ice melting. Phylogenetic analysis of anchovy mtDNA provides a reconstruction of population history in the Mediterranean, which is consistent with the geological information.      

Morphometric and molecular characterization of Kudoa encrasicoli n. sp. (Myxozoa: Myxosporea) from the European anchovy,Engraulis encrasicolus (L.) (Clupeiformes: Engraulidae)

Systematic Parasitology - The European anchovy represents the main fisheries for countries in the Mediterranean and Black Sea basins. The skeletal muscle of 13 of 48 (27.1%) Engraulis encrasicolus...