Northern Mediterranean Area Research Articles

Short communication: Edible wild mushrooms of the Northern Mediterranean area - Sectorial analysis and future perspectives

Aim of study: Wild mushrooms are among the most widespread non-wood forest products in the Mediterranean region contributing to the rural economies. However, the wild mushroom sector still faces problems along its supply chain that can compromise its future in a scenario of increasing demand. The aim of this study was to analyse the current epigeous wild mushroom sector.
 Area of study: Representative countries of the Mediterranean region: Spain, France, Italy, Croatia and Greece.
 Materials and methods: The analysis was carried out through a structured Delphi survey conducted in two rounds, with a questionnaire divided into four groups: 1) supply chain description, 2) sectorial SWOT analysis, 3) future challenges and 4) sectorial resilience increase. The Delphi survey started with the selection of an expert panel that included 14 representatives of the wild mushroom supply chain such as forest owners, mushroom pickers, processing industry and consumers.
 Main results: The results obtained from the expert panel confirmed the complexity of the wild mushroom supply chain with the following sectorial challenges: i) Traceability and sustainability is fundamental for the final consumer, ii) Sectorial administration should be more coordinated, iii) Mushroom picking should be regulated, as the grey market will decrease.
 Research highlights: The study identified the most important actions that will strengthen the links among sectorial actors and interconnect gastronomy with mushrooms sector. The creation of a common EU list of commercial mushroom species and the development of a taxation system together with the product traceability were also addressed.

Chronic Cold Stress Alters the Skin Mucus Interactome in a Temperate Fish Model.

Temperate fish are particularly sensitive to low temperatures, especially in the northern Mediterranean area, where the cold season decreases fish-farm production and affects fish health. Recent studies have suggested that the skin mucus participates in overall fish defense and welfare, and therefore propose it as a target for non-invasive studies of fish status. Here, we determine the mucus interactome of differentially expressed proteins in a temperate fish model, gilthead sea bream (Sparus aurata), after chronic exposure to low temperatures (7 weeks at 14°C). The differentially expressed proteins were obtained by 2D-PAGE of mucus soluble proteins and further assessed by STRING analyses of the functional interactome based on protein-protein interactions. Complementarily, we determined mucus metabolites, glucose, and protein, as well as enzymes involved in innate defense mechanisms, such as total protease and esterase. The cold mucus interactome revealed the presence of several subsets of proteins corresponding to Gene Ontology groups. “Response to stress” formed the central core of the cold interactome, with up-regulation of proteins, such as heat shock proteins (HSPs) and transferrin; and down-regulation of proteins with metabolic activity. In accordance with the low temperatures, all proteins clustered in the “Single-organism metabolic process” group were down-regulated in response to cold, evidencing depressed skin metabolism. An interactome subset of “Interspecies interaction between species” grouped together several up-regulated mucus proteins that participate in bacterial adhesion, colonization, and entry, such as HSP70, lectin-2, ribosomal proteins, and cytokeratin-8, septin, and plakins. Furthermore, cold mucus showed lower levels of soluble glucose and no adaptation response in total protease or esterase activity. Using zymography, we detected the up-regulation of metalloprotease-like activity, together with a number of fragments or cleaved keratin forms which may present antimicrobial activity. All these results evidence a partial loss of mucus functionality under chronic exposure to low temperatures which would affect fish welfare during the natural cold season under farm conditions.

Variations in yield and gluten proteins in durum wheat varieties under late-season foliar versus soil application of nitrogen fertilizer in a northern Mediterranean environment.

With the increasing demand for high-quality foodstuffs and concern for environmental sustainability, late-season nitrogen (N) foliar fertilization of common wheat is now an important and widespread practice. This study investigated the effects of late-season foliar versus soil N fertilization on yield and protein content of four varieties of durum wheat, Aureo, Ariosto, Biensur and Liberdur, in a three-year field trial in northern Italy. Variations in low-molecular-weight glutenins (LMW-GS), high-molecular-weight glutenins (HMW-GS) and gliadins were assessed by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). It was found that N applied to the canopy did not improve protein rate compared with N application to the soil (general mean 138 mg g-1 ), but moderately increased productivity in the high-yielding varieties Liberdur and Biensur (three-year means 7.23 vs 7.13 and 7.53 vs 7.09 t ha-1 respectively). Technological quality was mainly related to variety choice, Aureo and Ariosto having higher protein rates and glutenin/gliadin ratios. Also found was a strong 'variety × N application method' interaction in the proportions of protein subunits within each class, particularly LMW-GS and gliadins. A promising result was the higher N uptake efficiency, although as apparent balance, combined with higher HMW/LMW-GS ratio in var. Biensur. Late-season foliar N fertilization allows N fertilizer saving, potentially providing environmental benefits in the rainy climate of the northern Mediterranean area, and also leads to variety-dependent up-regulation of essential LMW-GS and gliadins. Variety choice is a key factor in obtaining high technological quality, although it is currently associated with modest grain yield. This study provides evidence of high quality in the specific high-yielding variety Biensur, suggesting its potential as a mono-varietal semolina for pasta production. © 2017 Society of Chemical Industry.

Contrasting phylogeography of two Western Palaearctic fish parasites despite similar life cycles

AbstractAimWe used comparative phylogeography of two intestinal parasites of freshwater fish to test whether similarity in life cycle translates into concordant phylogeographical history. The thorny‐headed worms Pomphorhynchus laevis and P. tereticollis (Acanthocephala) were formerly considered as a single species with a broad geographical and host range within the Western Palaearctic.LocationCentral and eastern parts of Northern Mediterranean area, Western and Central Europe, Ponto‐Caspian Europe.MethodsA mitochondrial marker (COI) was sequenced for 111 P. laevis and 50 P. tereticollis individuals and nuclear ITS1 and ITS2 sequences were obtained for 37 P. laevis and 21 P. tereticollis. Genetic divergence, phylogenetic relationships and divergence time were estimated for various lineages within each species, and their phylogeographical patterns were compared to known palaeogeographical events in Western Palaearctic. Biogeographical histories of each species were inferred.ResultsThe two species show very different phylogeographical patterns. Five lineages were identified in P. laevis, partially matching several major biogeographical regions defined in the European riverine fish fauna. The early stages of P. laevis diversification occurred in the peri‐Mediterranean area, during the Late Miocene. Subsequent expansion across Western Europe and Russia was shaped by dispersal and vicariant events, from Middle Pliocene to Middle Pleistocene. By contrast, P. tereticollis has differentiated more recently within the Western and Central parts of Europe, and shows weak geographical and genetic structuring.ConclusionOur study highlights weak to moderate similarity in the phylogeographical pattern of these acanthocephalan parasites compared to their amphipod and fish hosts. The observed differences in the timing of dispersion and migration routes taken may reflect the use of a range of final hosts with different ecologies and dispersal capabilities. By using a group underrepresented in phylogeographical studies, our study is a valuable contribution to revealing the biogeography of host–parasite interactions in continental freshwaters.

Rickettsia spp. in Dermacentor marginatus ticks: analysis of the host-vector-pathogen interactions in a northern Mediterranean area.

In this work, we have analyzed the key features of Rickettsia spp. maintenance in Dermacentor marginatus ticks in four regions of the northern Mediterranean area, where extensive investigations are currently lacking. For this purpose, 380 adult D. marginatus ticks were collected from vegetation and wild ungulates during a 3-year study. A host-vector-pathogen interaction approach was applied to investigate the key components of the disease systems and evaluate their respective weight in the intensity of infection in natural foci. A high variability in the R. slovaca infection rate among sampling sites was observed, whereas R. raoultii was sporadically present and at low infection rates. Dermacentor marginatus presence was confirmed in all the investigated regions. The local wild boar population showed a strong association with adult D. marginatus ticks. The results of this investigation suggest that wild boars not only maintain D. marginatus populations by feeding adult ticks, but may also have a potential role in the eco-epidemiology of rickettsioses, as carriers of rickettsiae-infected ticks. The public health implications of these results are discussed.

Change points in predictors–predictand relationships within the scope of statistical downscaling

ABSTRACTA statistical downscaling approach allowing for change points in the relationships between atmospheric predictors and local precipitation is introduced. Change point analysis within generalized linear models, and change points in the predictor characteristics were used to develop a change point statistical downscaling approach. The approach is illustrated for station‐based winter precipitation in the Mediterranean area.In this study, 94 stations were considered. The change point analysis yielded 37 stations with robust change points in the predictors–precipitation relationships. An added value regarding statistical model performance of the change point approach compared to the use of statistical models without change points was observed for 15 out of the 37 stations. In the projections under enhanced greenhouse gas forcing the application of the change point approach for the 15 stations affects the downscaled precipitation amounts, with significant differences compared to the application of downscaling models without change points for about one third of these stations.Under RCP4.5 and RCP8.5 scenario conditions, mainly increases of winter precipitation are projected until the end of the 21st century for parts of the western and northern Mediterranean area, whereas the north‐eastern and eastern Mediterranean areas are affected by decreases.

Evaluating Digital Soil Mapping approaches for mapping GlobalSoilMap soil properties from legacy data in Languedoc-Roussillon (France)

Digital Soil Mapping is becoming increasingly operational because of shared approaches, clear specifications (e.g., GlobalSoilMap) and more “practical” applications across the planet. In a 27,236km2 French region located in the Northern Mediterranean area, this study evaluated four well-known Digital Soil Mapping approaches that were possibly applicable in the French context for inferring the GlobalSoilMap (GSM) grid using freely available data from the French spatial data infrastructure. These approaches used for soil input either a legacy 1:250,000 scale soil map—an area-weighted mean of soil mapping units and spatial disaggregation of soil mapping units (simulated)—or a set of 2024 legacy-measured soil profiles (1 profile/13.5km2) associated with a set of soil covariates using random forest and random forest plus kriging. These methods provided estimates of 29 soil properties over a 100m by 100m grid, i.e., clay, sand, silt, coarse fragment, organic carbon contents, pH and CEC, at the four upper GSM-specified depth intervals, plus soil depth.This experiment showed that the performances in mapping soil properties were highly variable (from R2=0 to R2=0.79). They were strongly correlated with the amount of spatially-structured variance of the soil properties captured by the available soil data. For example better performances were observed for organic carbon that is driven by large-scale climate variations than for texture and soil depth that are driven by short scale variations of parent materials and erosion–deposition ratio along a slope. Furthermore, the profile-based DSM models generally outperformed the soil map-based DSM models, and kriging did not improve the results of random forest. Finally improving the quality of soil data input was considered as the best way to improve the current mapping performances.In addition to providing a GlobalSoilMap proof-of-concept for Northern Mediterranean areas, this paper illustrates how a prior analysis of the available soil data may help in the anticipated estimation of the mapping performances and in the prior selection of the most promising DSM models to reach these performances.

Testing Species Delimitations in Four Italian Sympatric Leuciscine Fishes in the Tiber River: A Combined Morphological and Molecular Approach

Leuciscine fishes represent an important component of freshwater ichthyofauna endemic to northern Mediterranean areas. This lineage shows high intra-specific morphological variability and exhibits high levels of hybridization, two characteristics that contribute to systematic uncertainties, misclassification of taxa and, potentially, the mismanagement of biodiversity. This study focused on brook chub, Squalius lucumonis, an endemic taxon of Central Italy. The taxonomic status of this species has long been questioned, and a hybrid origin from sympatric leusciscines (S. squalus x Rutilus rubilio, or S. squalus x Telestes muticellus) has been hypothesised. A phenotypic (evaluating shape and meristic counts) and genetic (using mitochondrial and nuclear markers) investigation of these four taxa was conducted to test species delimitation in sympatric areas and to evaluate the taxonomic status of S. lucumonis. One hundred and forty-five individuals of all four taxa were collected within streams of the lowest portion of the Tiber River basin and analysed; this region encompasses a large portion of the S. lucumonis distribution. The different morphological and genetic approaches were individually examined, compared, and then combined in a quantitative model to both investigate the limits of each approach and to identify cases of misclassification. The results obtained confirm the cladogenetic non-hybrid origin of S. lucumonis, highlight the need for immediate conservation actions and emphasise the value of an integrated approach in the study of leuciscines evolution.

Genetic relationships between local North African apricot (Prunus armeniaca L.) germplasm and recently introduced varieties

Graft and seed propagated apricots in North Africa (Algeria, Morocco and Tunisia) are identified as being from the southwestern Mediterranean gene pool. However, recently introduced varieties from northern Mediterranean areas are also encountered in this region. Do gene exchanges occur between local apricot and introduced varieties? We addressed this question by analyzing the genetic structure of 183 accessions using 24 nuclear microsatellite markers and a model-based Bayesian clustering method. We classified these accessions into 4 genetic clusters: cluster 1 from Morocco, cluster 2 from northern, central and southern Tunisia which were all propagated by grafting, cluster 3 from the oasis region in Tunisia and the Messaad region in Algeria, and finally, cluster 4 (green) included accessions belonging to the northern Mediterranean gene pool. These accessions were more diversified and genetically differentiated with respect to local North African apricot. The results revealed the presence of admixed accessions between the local gene pool and introduced varieties, mainly in seed propagated populations, thus highlighting the presence of gene exchanges between northern and southern Mediterranean countries. Our findings should be useful for improving the management and conservation of Maghrebian apricot genetic resources.

Reproductive biology of the palm borer, Paysandisia archon (Lepidoptera: Castniidae)

Paysandisia archon (Burmeister, 1980) (Lepidoptera: Castniidae) is an accidentally introduced pest that damages palm trees in the northern Mediterranean area. To our knowledge, there are no experimental studies on its mating behaviour, and little is known about its biology and ecology. In the present study, we used outdoor experiments to investigate several characteristics of the reproductive behaviour of P. archon: sexual maturity, diel periodicity of mating, occurrence of polyandry and delay between mating and laying eggs. The results indicate that 73% of the individuals studied were sexually mature three hours after adult emergence. Mating peaked between 14:00 h and 15:00 h and 87% of the females were fertilized and started laying eggs 1.25 (± 1.14) days after mating. Females were generally monandrous, but nevertheless remained attractive after mating. The results of this study provide the necessary background knowledge for studying several aspects of P. archon reproductive biology, in particular oviposition, sex pheromones and their role in mediating mating behaviour in this pest. These results are the first step in developing tools for monitoring populations of this pest.

Low-temperature challenges to gilthead sea bream culture: review of cold-induced alterations and ‘Winter Syndrome’

Although gilthead sea bream have been cultured successfully for the last two decades they are particularly sensitive to low temperature. Especially in the northern Mediterranean area, cold affects fish health and decreases fish-farm production, and may even cause mortality through what is known as ‘Winter Disease’ or ‘Winter Syndrome’. This paper reviews the diagnosis and physiological effects of this disease, focusing on recent studies of cold-induced alterations in gilthead sea bream physiology. ‘Winter Syndrome’ is characterised by multi-organ dysfunction entailing hyposensitivity, erratic swimming, pale and friable livers, necrotic muscles, atrophy of the exocrine pancreas, and distended digestive tract. Its complex aetiology involves several factors such as thermal stress, metabolic depression, immune suppression, and occasional opportunistic pathogens. Low temperatures may be the initial cause of all these factors, except pathogen action. Indoor studies have demonstrated that a drop in temperature causes cold-induced fasting, thermal stress and metabolic depression. These immediate effects are related to an ionic imbalance caused by malfunctions of the gills and digestive system. They are also related to a fatty liver, which appeared steatotic and affected hepatic metabolism and blood composition. The result is a lower immune capacity and fish that are more susceptible to infection. There is no significant thermal compensation under cold conditions and in this situation any additional stress factors can cause fish to suffer metabolic collapse. This study reviews the physiological and zootechnical origins of the disease and, where possible, recommends ways of improving culture conditions during pre-cold, cold and recovery periods.

Population structure and geographical subdivision of theLeishmania majorvectorPhlebotomus papatasias revealed by microsatellite variation

Multi-locus microsatellite typing (MLMT) has been employed to infer the population structure of Phlebotomus papatasi (Scopoli) (Diptera: Psychodidae) sandflies and assign individuals to populations. Phlebotomus papatasi sandflies were collected from 35 sites in 15 countries. A total of 188 P. papatasi individuals were typed using five microsatellite loci, resulting in 113 different genotypes. Unique microsatellite signatures were observed for some of the populations analysed. Comparable results were obtained when the data were analysed with Bayesian model and distance-based methods. Bayesian statistic-based analyses split the dataset into two distinct genetic clusters, A and B, with further substructuring within each. Population A consisted of five subpopulations representing large numbers of alleles that were correlated with the geographical origins of the sandflies. Cluster B comprised individuals collected in the Middle East and the northern Mediterranean area. The subpopulations B1 and B2 did not, however, show any further correlation to geographical origin. The genetic differentiation between subpopulations was supported by F statistics showing statistically significant (Bonferroni-corrected P < 0.005) values of 0.221 between B2 and B1 and 0.816 between A5 and A4. Identification of the genetic structure of P. papatasi populations is important for understanding the patterns of dispersal of this species and to developing strategies for sandfly control.

The Vegetation Resilience After Fire (VRAF) index: Development, implementation and an illustration from central Italy

A suitable index is proposed to evaluate the natural short–medium-term recovery capability of vegetation in burnt areas. The study area covers 2450km2 in western Tuscany (Province of Pisa, Italy). This region is characterized by a typical Mediterranean climate and is subject to fire damage during the dry summer season. Damage is mitigated where a natural rapid regrowth of vegetation prevents soil erosion, supporting the return to a natural pre-fire state.The Vegetation Resilience After Fire (VRAF) index is based on the vegetation association, soil type and geology, and on morphological features such as slope and aspect. The results are proposed as georeferenced maps defining areas with different vegetation resilience for both high and medium burn severity. The VRAF maps estimate the natural ability of vegetation to recover after fire, and suggest where human intervention is required to improve this capability. The VRAF index was checked by monitoring vegetation regrowth after fire in three burnt areas over a five-year period using spectral signatures, the feature space and the NDVI derived from remote sensing data. This analysis indicates that the high values of the VRAF index correspond to a recovery period of almost three years. Field surveys were performed to further test the results. On the whole, the VRAF index is a good parameter for assessing the capability of vegetation to recover in northern Mediterranean areas.

Climate change projections for the Mediterranean region

We present a review of climate change projections over the Mediterranean region based on the most recent and comprehensive ensembles of global and regional climate change simulations completed as part of international collaborative projects. A robust and consistent picture of climate change over the Mediterranean emerges, consisting of a pronounced decrease in precipitation, especially in the warm season, except for the northern Mediterranean areas (e.g. the Alps) in winter. This drying is due to increased anticyclonic circulation that yields increasingly stable conditions and is associated with a northward shift of the Atlantic storm track. A pronounced warming is also projected, maximum in the summer season. Inter-annual variability is projected to mostly increase especially in summer, which, along with the mean warming, would lead to a greater occurrence of extremely high temperature events. The projections by the global and regional model simulations are generally consistent with each other at the broad scale. However, the precipitation change signal produced by the regional models shows substantial orographically-induced fine scale structure absent in the global models. Overall, these change signals are robust across forcing scenarios and future time periods, with the magnitude of the signal increasing with the intensity of the forcing. The intensity and robustness of the climate change signals produced by a range of global and regional climate models suggest that the Mediterranean might be an especially vulnerable region to global change.

Extreme sea levels in two northern Mediterranean areas

The ‘calibrated’ Joint Probability Method (JPM) is used to estimate extreme sea levels at four stations in the northern Adriatic (Trieste, and three observatories in the lagoon of Venice area) and three stations in the Gulf of Lions (Port-Vendres, Sete, and Grau-de-la-Dent in the Rhone delta). The JPM, that involves empirical evaluation of the probability of tide and surge separately, can also be used for short records, but tends to overestimate return levels. A correction is therefore necessary. The correction coefficient Cc adopted is deduced from the dataset, by imposing to the maximum record height to coincide with the return period of the record length. Cc, which appears linked to tide-surge interaction and seasonal effects, is generally less than unit. It calibrates the whole series of extreme estimations to the observed maximum. If Cc is >1, it provides evidence that exceptional surges have occurred during the period considered. In this case its application would lead to overestimation of extreme sea levels and other methods of calculation should be preferred. This is the case, for example, for the Lagoon of Venice. Finally, extreme levels with estimated return times of 2, 10, 50 and 100 years, respectively, are proposed for each site.

Is there seasonal variation in size and mass of Red Admirals Vanessa atalanta on Capri, Italy?

I present data on seasonal variation in wing length and mass of Red Admirals Vanessa atalanta captured on Capri, Italy, during spring and autumn. The Red Admiral is a migratory butterfly that migrates north throughout Europe each year and then heads back south in the autumn. During the winter they are mostly found in the northern Mediterranean area where they previously were thought to hibernate, but recent data suggest that a new generation is produced before spring migration. The Red Admirals captured on Capri showed no difference in dry mass between the two seasons, when taking size in account, but had significantly longer wings in autumn. This suggests that a new generation is produced during winter.

Heterodera latipons on barley in Jordan

A survey of major barley-growing areas in Jordan was conducted to determine the prevalence and degree of infestation of the Mediterranean cereal cyst nematode (MCCN) Heterodera latipons. The nematode was found in several locations in the northern and southern Mediterranean and the eastern desert areas of Jordan, but it was not detected in the northern Jordan valley and the southern desert areas. In those areas where the cyst nematode occurred, the incidence varied between areas from 30 to 100%. The degree of infestation varied from moderate to very severe. Infestation was most severe in the fields of the Northern Mediterranean area. The MCCN completed one life cycle per growing season. Studies on three isolates of the nematode from three areas, Ar-Ramtha, Madaba, and Al- Karak, revealed that the morphometrics varied little among these isolates. These three isolates as a whole varied in their virulence to two commonly used barley cultivars, Rum and Acsade 106, being more virulent on cv. Rum than on cv. Acsade 106. However, the isolates also varied among each other in their virulence to the same cultivar, Ar-Ramtha being the most virulent on cv. Rum, Madaba the most virulent on cv. Acsade 106.

The wood of “C” and “F” Roman ships found in the ancient harbour of Pisa (Tuscany, Italy): the utilisation of different timbers and the probable geographical area which supplied them

During the excavation of the Etruscan and Roman harbour of Pisa, several shipwrecks were found. The wooden timbers constituting the ship C and ship F (which date back to the first and the second century A.D., respectively, as attested by archaeological findings) were selected in order to collect information about the technological knowledge of the time. Pinus pinaster Aiton was essentially utilised for the planking of ship C and Quercus sp. c aducifolia for that of ship F. The choice of timber for the other parts of ship C hull was much more differentiated. Ship C seems to be built in a careful way and its characteristics when added to its overall lightness, seem to reflect its use as a higher capacity boat built for sea sailing. Ship F seems more linked to short voyages in inner fresh waters. The utilisation of different woods was linked not only to the technological characteristics of wood, but also to their easy availability. Palynological analysis, carried out on the clay sediments embedding the shipwrecks, has shown that the flora of Pisa area in that time period would have allowed the acquisition of all the timber species used for both the ships’ construction, with the exception of the fig wood. However, a foreign origin of the timber from somewhere else in the Northern Mediterranean area has not been excluded.

Micropropagation of Limonium cordatum (L.) Mill. for conservation purposes

SummaryL. cordatum (L.) Mill. is a Ligurian endemism of the Northern Mediterranean area. Human use of the coast and seaside resorts has modified the areas where this plant has its habitat. Reviews of the literature and field investigations have enabled a progressive decrease in the population and in the number of specimens in the areas occupied by the species to be measured. Micropropagation tests pointed out the possibility of ex situ multiplication activities. The use of explants from the basal part of the inflorescence stems was very successful in obtaining many new vegetative buds producing shoots with a normal appearance and development. In L. cordatum, low BA concentrations increase the rate of production of new shoot but had an inhibitory effect on rooting; on the contrary, the addition of auxin to the medium leads to increased root formation but inhibits shoot development. According to our experience, a micropropagation procedure based on the use of a simple MS medium without addition of growth regulators, is suggested for L. cordatum. In situ planting could be possible, with good results. Once young plants had survived in vivo transplanting they incurred no further adaptation problems.

Electrophoretic analysis of stock structure in Northern Mediterranean anchovies,Engraulis encrasicolus

Starch gel electrophoresis of allozymes was used to investigate the genetic stock structure of European anchovies (Engraulis encrasicolus L.) in the northern Mediterranean area. Twenty-four putative enzyme-coding loci were examined in 634 fish, constituting 13 samples caught in the Adriatic, Tyrrhenian, Ionian, and Aegean seas, the Sicilian Channel and the Bay of Biscay, between March 1993 and May 1994. Eight loci were monomorphic in all samples, eight were weakly polymorphic (p=0.99), and a further eight exhibited common allele frequencies <0.95 (p=0.95). Over 99% of tests indicated that genotypic proportions were in accordance with Hardy-Weinberg predictions. Average mean unbiased heterogeneity per locus (HL) was 0.055 and the effective mean number of alleles per locus was 1.17. Genetic distance between samples was low (maximum Nei's D=0.009). An outgroup sample from the Bay of Biscay was easily distinguishable from Mediterranean fish, due to fixation at a number of polymorphic loci. Chi-square analyses revealed significant differences (p<0.05) between Mediterranean samples at six loci (G3PDH-1, G3PDH-2, IDHP-2, mMEP, GAPDH-1 and GPI), and GAPDH-1 and GPI in particular showed obvious heterogeneity between seas. Gene diversity analysis indicated that 96.6% of variation was within samples, with only 3.4% between samples (GST). 77% of this between-sample variation was partitioned between seas, the remainder accounting for spatial and temporal variation within seas. The results are discussed in relation to the hydrographic and physical barriers to migration in the study area, and compared with those obtained by other workers. The possible consequences of stock integrity in clupeoid fish with regard to resilience and recovery from collapse are discussed.