Autoecology and population dynamics of smooth sandeel (Gymnammodytes semisquamatus (Jourdain, 1879)) in the Maritime-Terrestrial National Park of the Atlantic Islands of Galicia (NW of Spain)

Adapting fisheries management to the spatial variability in the reproductive cycle: the case of the sword razor clam in Galicia (NW Spain)

Alien predators exert severe effects on island ecosystems, and their eradication from island habitats may therefore be necessary to conserve the native biota. Efforts are being made to eradicate the American mink (Neovison vison) from the Atlantic Islands of Galicia National Park (NW Spain), a protected site inhabited by vulnerable island fauna. We applied a molecular genetic approach to elucidate the source of the invaders and to evaluate the effectiveness of the trapping programme. We collected mink scats in the field and obtained tissue samples from culled mink. Populations of feral mink were known to be present in coastal areas close to the National Park archipelagos in the 1980–1990s. However, the molecular findings suggest that these populations were not the main source of the mink populations that colonized the islands during the 2000s. Recent releases from farms directly on to the islands are a more likely source of these invaders. Genetic analysis suggested that mink reproduced successfully on the islands and were relatively isolated from other mainland populations. The findings also suggest that most of the culled mink were juveniles, probably because it was more difficult to catch adults. Since mink are short-lived animals, it seems that eradication may also be achieved when a large proportion of juveniles are culled in isolated and small populations.

Characterizing the fishing strategies and the temporal dynamics of the small-scale fleet operating in the Cíes Islands (NW Spain)

Changes in soil properties after a wildfire in Fragas do Eume Natural Park (Galicia, NW Spain)

Socioeconomic and biological causes of management failures in European artisanal fisheries: the case of Galicia (NW Spain)

BackgroundThe most recent Alu insertions reveal different degrees of polymorphism in human populations, and a series of characteristics that make them particularly suitable genetic markers for Human Biology studies. This has led these polymorphisms to be used to analyse the origin and phylogenetic relationships between contemporary human groups. This study analyses twelve Alu sequences in a sample of 216 individuals from the autochthonous population of Galicia (NW Spain), with the aim of studying their genetic structure and phylogenetic position with respect to the populations of Western and Central Europe and North Africa, research that is of special interest in revealing European population dynamics, given the peculiarities of the Galician population due to its geographical situation in western Europe, and its historical vicissitudes.ResultsThe insertion frequencies of eleven of the Alu elements analysed were within the variability range of European populations, while Yb8NBC125 proved to be the lowest so far recorded to date in Europe.Taking the twelve polymorphisms into account, the GD value for the Galician population was 0.268. The comparative analyses carried out using the MDS, NJ and AMOVA methods reveal the existence of spatial heterogeneity, and identify three population groups that correspond to the geographic areas of Western-Central Europe, Eastern Mediterranean Europe and North Africa. Galicia is shown to be included in the Western-Central European cluster, together with other Spanish populations. When only considering populations from Mediterranean Europe, the Galician population revealed a degree of genetic flow similar to that of the majority of the populations from this geographic area.ConclusionThe results of this study reveal that the Galician population, despite its geographic situation in the western edge of the European continent, occupies an intermediate position in relation to other European populations in general, and Iberian populations in particular. This confirms the important role that migratory movements have had in the European gene pool, at least since Neolithic times. In turn, the MDS and NJ analyses place Galicia within the group comprised of Western-Central European populations, which is justified by the influence of Germanic peoples on the Galician population during the Middle Ages. However, it should also be noted that some of the markers analysed have a certain degree of differentiation, possibly due to the region's position as a 'cul-de-sac' in terms of Iberian population dynamics.

The Atlantic Islands of Galicia Maritime/Terrestrial National Park hosts one of the largest breeding colonies of yellow-legged gull (Larus michahellis) in the world. In 2002, a new yellow-legged gull breeding colony was established on the Punta Muxieiro dune complex, which also harbors rare and threatened plant species and habitat types of community interest according to Directive 92/43/EEC. This study assesses the effect of this colony on two habitats of community interest: white dunes and grey dunes. For this purpose, plant cover and soil properties, composition, and nutrient content were monitored in plots with different gull densities. Moreover, historic aerial images were compiled to observe changes in the plant landscape of the dune system. The results showed that, despite the recentness of the occupation of the dune system by yellow-legged gull species, significant changes in acidic–alkaline processes and nutrient availability were already observed in soils. Soils in plots with higher gull density showed more acidic pH values and a higher content of the most labile N and P fractions. Moreover, a decrease in plant cover and number of species was also demonstrated in plots with higher gull densities. Finally, the presence of ruderal and alien species such as Urtica membranacea and Parietaria judaica was also observed.

Enrichment of trace elements in colonies of the yellow-legged gull (Larus michahellis) in the Atlantic Islands National Park (Galicia-NW Spain)

To study the distribution of Lymnaea truncatula in the Porma river basin (León, NW Spain) and its helminth fauna, malacological samplings were carried out at 66 points in the basin and the presence of these molluscs was detected in 31. To trace the dynamics of this mollusc population and the prevalence and intensity of its infection by trematodes, malacological samplings were made at fortnightly intervals over two years at five locations, situated in the upper and middle regions of the river Porma basin. To confirm the identity of the larval stages found in the molluscs, second intermediate and/or definitive hosts, depending on the trematode species, were experimentally infected to complete the life cycles. Two different species of Plagiorchiidae and one of Notocotylidae were identified. The infection prevalence of Plagiorchis elegans for the 6291 specimens of L. truncatula examined was 2.8% and infection was observed in snails collected in 7 of the 31 sample localities. This parasite was found in all months of the year, with the highest prevalence observed in July and October. When the corrected frequency values were considered, a slightly positive relationship was observed between the infection prevalence and the latter months. The highest percentages of snails harbouring immature sporocysts were detected in March and June-July, while the highest percentages with sporocysts containing mature cercariae were observed in spring and at the end of summer-autumn, and cercarial shedding in the latter. Of the 6291 L. truncatula examined 0.3% were infected by sporocysts of Opisthioglyphe ranae.(ABSTRACT TRUNCATED AT 250 WORDS)

Biological, social and economic information is necessary in order to assess the effectiveness of fisheries management measures. Indicators of the economic performance of fishing vessels are a useful tool for improving management strategies and are necessary for the implementation of the ecosystem approach to fisheries management in European waters. However, they are usually difficult to obtain from official data, which are often biased, incomplete and/or lacking in spatial references. In this paper, a broad set of economic indicators is provided for the fleet operating around the Cies Islands (NW Spain) during 2008, based on data obtained from interviews with fishers. Artisanal and purse seiners were the most representative segments of the study fleet. While artisanal vessels played an essential social role in Galician fishing communities, purse seiners were a fundamental economic segment as they had the highest profitability per vessel. Both segments appeared to be economically profitable in 2008, with a moderate rate of return on investment for artisanal vessels (around 7%) and a high rate (around 13%) for purse seiners. The present study identified the waters around the Cies Islands as an essential fishing ground for the study fleet due to the high cash flow that it generated. As part of this area now belongs to a national marine park, our results represent a reference point for decision-makers and for the development of effective management strategies.

Simple SummaryThe population of the pipefish Syngnathus acus inhabiting Cíes Archipelago (NW Spain) was monitored in 2017–2018 for spatial and temporal changes in abundances, reproduction traits, trophic niche occupancy, and dietary regimes across reproduction states, through an isotopic (δ13C and δ15N) approach. The population consisted almost exclusively of large adults, whose abundances decreased significantly from mid-autumn after the breeding season. S. acus is a secondary consumer that prefers amphipods, but mature specimens were less selective than immature fish. The present study highlights the outstanding size of the fish and the exceptional occurrence of breeders on the studied area.The great pipefish Syngnathus acus is one of the most representative European syngnathids, being highly associated with seagrass and macroalgal beds. Surprisingly, the ecology of this large ovoviviparous marine fish has received scanty attention. The population inhabiting three sites on Cíes Archipelago (Atlantic Islands National Park, NW Spain) was monitored in 2017–2018 for spatial and temporal changes in abundances, reproduction traits, trophic niche occupancy, and dietary regimes across reproduction states, through an isotopic (δ13C and δ15N) approach. Abundances were highly variable across seasons and sites, decreasing significantly from mid-autumn. The population consisted almost exclusively of large adults that migrate by the end of the breeding season, which extended from mid-spring to summer. Operational sex ratios suggest that the species is sex-role reversed. S. acus is a secondary consumer (Trophic position = 3.36 ± 0.05), preferring amphipods but displaying annual and seasonal dietary plasticity. Mature fish were less selective than immatures (especially females), with a higher preference for amphipods (36–68%) in the former. The second most-preferred prey were carideans, copepods, or isopods, depending on the year and the reproduction state. Overall, the wider trophic niches in females and immature specimens compared to males and mature fish would indicate a higher variability in both the use of prey resources and/or their origin. The present study highlights the trophic plasticity and unique features of S. acus population in the Cíes Archipelago, especially regarding the outstanding size of the fish and the exceptional occurrence of breeders.

ABSTRACTSpanish National Parks (NPs) are protected areas for biodiversity conservation, including two Maritime–Terrestrian NPs: The Atlantic Islands of Galicia, PNIA (NW Spain) and Archipelago of Cabrera, PNAC (Balearic Islands). This study was aimed to conduct a 3‐year genetic survey of syngnathid fish species (i.e. seahorses and pipefish) identified in both NPs and nearby unprotected areas, using mitochondrial and microsatellite markers. A diversity of species was identified with differential distribution among NPs and adjacent areas studied. Pipefish (Syngnathus acus, S. abaster, S. typhle, Entelurus aequoreus, Nerophis lumbriciformis, N. maculatus, and N. ophidion) predominated, while seahorses (Hippocampus guttulatus) were much less abundant. Genetic data and phylogenetic analysis clarified in situ morphological identification. Mitochondrial haplotypes for each species clustered into monophyletic groups, supporting the identification of a cryptic lineage of S. abaster in PNAC distinct from eastern Mediterranean populations of this species. Intraspecific genetic diversity was evaluated at spatial and temporal scale for population samples recorded during the survey period, providing valuable information for individual resampling traceability and delineating management units. Temporal stability in genetic diversity and gene flow with adjacent areas were observed for dominant species within each NP in the 3‐year period studied. However, significant intraspecific differentiation was detected between populations identified in Atlantic and Mediterranean NPs. This study provides valuable reference genetic data for future monitoring and to identify distribution or research gaps for further studies towards the conservation of syngnathid populations in Spanish marine NPs, which serve as umbrella species for the preservation of vulnerable coastal ecosystems and habitats.

At present, biodiversity conservation and management in Spanish National Parks in Spain must respond to a series of regulations at a European, national and regional level, also adapting to scientific-technical progress. The availability of increasingly precise data on the values to be conserved (ecosystems, habitats, species, geodiversity) in these protected areas enables more detailed management, but also requires more rigorous, powerful, and multidisciplinary tools. Maritime-terrestrial national parks are highly sensitive areas to public use, so their impact must be one of the most important factors to take into account when planning their management. This work evaluates the past and present challenges for conservation in Galician Atlantic Islands National Park (NW Spain), where biodiversity conservation and management has evolved over time in a significant way, providing a valid case study applicable to other national parks worldwide, as well as similar situations in other contexts and scenarios. Future challenges are arising in the National Park to improve the conservation status of natural habitats and wildlife, mainly through new European initiatives that may establish important synergies with other countries.

Human–wildlife interactions

The high-mountain lakes of Saliencia (El Valle, La Cueva, Calabazosa and Cerveriz), in the Somiedo Natural Park (Asturias, NW Spain), have been subject to different anthropogenic pressures, including metal mining, cattle grazing, damming activities and water channelling work for hydroelectric exploitation. This paper reports the results of a recent geochemical and limnological study conducted in these lakes, for which no previous study existed in the literature. Based on depth profiles of temperature, conductivity, pH and ORP, as well as dissolved oxygen, chlorophyll-a, organic carbon, nutrient and metal concentration, we discuss the impact of anthropogenic pressure on the lakes. In the sampling period (July to September, 2014-2016), most of the lakes showed a marked stratification with vertical gradients as a result of different physical and (bio)geochemical processes. All the lakes showed a good environmental state with no apparent metal pollution. However, this set of mountain lakes is not homogeneous with regard to nutrient availability, primary productivity, or hypolimnetic oxygen deficit and a range of trophic conditions exist from oligotrophic (El Valle) to eutrophic (Calabazosa). This trend shows a good correlation with total phosphorus concentration (e.g., 10 µg/L P in El Valle vs. 35 µg/L P in Calabazosa), though erosive processes in the catchment may also have contributed to increase the oxygen consumption rate through an import of allochthonous organic matter. Higher nitrate contents seem to characterize the areas with higher grazing pressure (e.g., El Valle), though the obtained data do not allow us to establish any evident relationship between cattle activity and eutrophication.