Spatial distribution patterns and movements of Holothuria arguinensis in the Ria Formosa (Portugal)

Holothurian populations are under pressure worldwide because of increasing demand for beche-de-mer, mainly for Asian consumption. Importations to this area from new temperate fishing grounds provide economic opportunities but also raise concerns regarding future over-exploitation. Studies on the habitat preferences and movements of sea cucumbers are important for the management of sea cucumber stocks and sizing of no-take zones, but information on the ecology and behavior of temperate sea cucumbers is scarce. This study describes the small-scale distribution and movement patterns of Holothuria arguinensis in the intertidal zone of the Ria Formosa national park (Portugal).Mark/recapture studieswere performed to record theirmovements over time on different habitats (sand and seagrass). H. arguinensis preferred seagrass habitats and did not show a size or life stage-related spatial segregation. Its density was 563 ind. ha−1 and mean movement speed was 10 m per day. Movement speed did not differ between habitats and the direction of movement was offshore during the day and shoreward during the night. Median home range size was 35 m2 and overlap among home ranges was 84%. H. arguinensis' high abundance, close association with seagrass and easy catchability in the intertidal zone, indicate the importance of including intertidal lagoons in future studies on temperate sea cucumber ecology since those systems might require different management strategies than fully submerged habitats

Characterization of 10 new tetranucleotide microsatellite markers for the European eagle owl, Bubo bubo: Useful tools for conservation strategies

Bubo bubo is the largest owl in the world, showing a wide geographical distribution throughout the Palaearctic region. It underwent a demographic decline in many European countries during the last century and was considered “vulnerable” (Annex II of the CITES). Nowadays, it is classified as “Least Concern” according to IUCN. Despite its ecological importance and conservation status, few polymorphic molecular markers are available to study its diversity and population genetics. We report on the isolation and development of 10 new microsatellites for the Eagle owl, B. bubo. All loci (10 tetra-nucleotide) are characterized by high polymorphism levels. Number of alleles ranged from 5 to 13 and expected heterozygosity varied from 0.733 to 0.840. These microsatellites would be very useful to assess the genetic diversity, connectivity patterns and parentage of B. bubo. This information will allow to establish new conservation strategies and improve the management of the species

Assessment of sea cucumber populations from the Aegean Sea (Turkey): first insights to sustainable management of new fisheries

Sea cucumber stocks have been overfished in many countries. As a consequence, several species (Holothuria polii, Holothuria tubulosa and Holothuria mammata) are now caught in Turkish waters without adequate knowledge on their biology and ecology. Here, we address their morphometry, relationships among gutted length and weight, population dynamics, temporal evolution of catches, and we provide the first insights about technical aspects of their fisheries. The largest size classes of H. polii are missing from our sampling collection, possibly due to the heavy fishery pressure on this species. Significant differences in the eviscerated length and weight were found among the Turkish sampled localities for H. polii and H. tubulosa, respectively. These differences could be explained by higher food availability in some areas and/or differential fishery pressure. The size and weight of H. tubulosa specimens were smaller than those registered for the same species in Greek waters, where this species is not fished. All the studied species showed allometric growth. In the last two years, the sea cucumber fishery in Turkey has been increasing rapidly, reaching a total production of ca. 555 000 kg in 2012 (80% H. polii and 20% H. tubulosa plus H. mammata). For a correct management of these species, we recommend: 1) the reestablishment of species-specific closed fishery season according to the specific reproductive cycle; 2) the assessment of the exploited stocks from the Northern Turkish coasts with estimates of recovery time of their populations; 3) the reduction of fishery efforts, mainly on H. polii and H. tubulosa and 4) the establishment of protected areas (where sea cucumber fisheries are forbidden) to conserve healthy populations which will favour the recruitment on nearby areas

Phosphoglucose isomerase variability of Cerastoderma glaucum as a model for testing the influence of environmental conditions and dispersal patterns through quantitative ecology approaches

Extreme conditions of coastal lagoons could directly modify the genetic patterns of species. The aim of this work was to investigate the influence of environmental conditions and small scale dispersal patterns on the phosphoglucose isomerase (PGI*) genetic variability of Cerastoderma glaucum from the Mar Menor coastal lagoon. For this purpose, 284 cockles were collected around the perimeter of the lagoon. Vertical polyacrylamide gel electrophoresis was used to scan for PGI* polymorphisms, giving a total of seven alleles. The spatial genetic distribution of the PGI* variability, which seems to be marked by the main circulation in the lagoon, discriminates four hydrological basins. In the central basin, a gradient of allelic composition reflects the circulation forced by the dominant winds and the main channel communicated to the open sea. This result is well supported by the salinity GAM model that defines this gradient. The other three basins are defined by the distribution of fine sand in a more complex model that tries to explain the isolation of the three sites localized inside these basins. The southern, western and northern basins show the lowest degree of interconnection and are considered the most confined areas of the Mar Menor lagoon. This situation agrees with the confinement theory for benthic assemblages in the lagoon. The greater degree of differentiation seen in the Isla del Ciervo population is probably due to recent human intervention on the nearby Marchamalo channel, which has been drained in recent years thus altering the influence of the Mediterranean Sea on the southern basin

Phylogeographical history of the white seabream Diplodus sargus (Sparidae): Implications for insularity

Partial sequences of the mitochondrial control region and its comparison with previously published cytochrome b (cyt-b) and microsatellite data were used to investigate the influence of island isolation and connectivity on white seabream genetic structure. To achieve this, a total of 188 individuals from four island localities (Castellamare and Mallorca, Mediterranean Sea; Azores and Canary Islands, Atlantic Ocean) and five coastal localities (Banyuls, Murcia and Tunisia, Mediterranean Sea; Galicia and Faro, Atlantic Ocean) were analysed. Results showed high haplotype diversity and low to moderate nucleotide diversity in all populations (except for the Canary Islands). This pattern of genetic diversity is attributed to a recent population expansion which is corroborated by other results such as cyt-b network and demographic analyses. Low differentiation among Mediterranean/Atlantic and coastal/island groups was shown by the AMOVA and FST values, although a weak phylogeographic break was detected using cyt-b data. However, we found a clear and significant island/ distance effect with regard to the Azores islands. Significant genetic differentiation has been detected between the Azores islands and all other populations. The large geographical distance between the European continental slope and the Azores islands is a barrier to gene flow within this region and historic events such as glaciation could also explain this genetic differentiation

Genetic diversity and connectivity remain high in Holothuria polii (Delle Chiaje 1823) across a coastal lagoon-open sea environmental gradient

Coastal lagoons represent habitats with widely heterogeneous environmental conditions, particularly as regards salinity and temperature,which fluctuate in both space and time. These characteristics suggest that physical and ecological factors could contribute to the genetic divergence among populations occurring in coastal lagoon and opencoast environments. This study investigates the genetic structure of Holothuria polii at a micro-geographic scale across theMar Menor coastal lagoon and nearbymarine areas, estimating the mitochondrial DNA variation in two gene fragments, cytochrome oxidase I (COI) and 16S rRNA (16S). Dataset of mitochondrial sequences was also used to test the influence of environmental differences between coastal lagoon andmarine waters on population genetic structure. All sampled locations exhibited high levels of haplotype diversity and low values of nucleotide diversity. Both genes showed contrasting signals of genetic differentiation (non-significant differences using COI and slight differences using 16S, which could due to different mutation rates or to differential number of exclusive haplotypes. We detected an excess of recent mutations and exclusive haplotypes, which can be generated as a result of population growth. However, selective processes can be also acting on the gene markers used; highly significant generalized additive models have been obtained considering genetic data from16S gene and independent variables such as temperature and salinity

Spatial patterns of genetic diversity in Mediterranean eagle owl Bubo bubo populations

Little information is available on the patterns of genetic connectivity in owls. We studied the genetic structure of the eagle owl Bubo bubo (Linnaeus, 1758) in southeastern Spain at two different spatial scales. Seven microsatellites previously described for this species were used, although only six loci amplified correctly. The observed low genetic variation could be explained by the short dispersal distance, high mortality rate and high degree of monogamy shown by this large nocturnal predator. As expected, the highest genetic isolation was detected in the geographically most isolated population. Significant genetic differentiation was found among study units separated by less than 50 km. The territorial analysis showed interesting connectivity patterns related with the gene flow and turnover rate of the breeding individuals. The lowest genetic diversity was found in the region with the largest population, which could imply incipient inbreeding

Do hatchery-reared sea urchins pose a threat to genetic diversity in wild populations?

In salmonids, the release of hatchery-reared fish has been shown to cause irreversible genetic impacts on wild populations. However, although responsible practices for producing and releasing genetically diverse, hatchery-reared juveniles have been published widely, they are rarely implemented. Here, we investigated genetic differences between wild and early-generation hatchery-reared populations of the purple sea urchin Paracentrotus lividus (a commercially important species in Europe) to assess whether hatcheries were able to maintain natural levels of genetic diversity. To test the hypothesis that hatchery rearing would cause bottleneck effects (that is, a substantial reduction in genetic diversity and differentiation from wild populations), we compared the levels and patterns of genetic variation between two hatcheries and four nearby wild populations, using samples from both Spain and Ireland. We found that hatchery-reared populations were less diverse and had diverged significantly from the wild populations, with a very small effective population size and a high degree of relatedness between individuals. These results raise a number of concerns about the genetic impacts of their release into wild populations, particularly when such a degree of differentiation can occur in a single generation of hatchery rearing. Consequently, we suggest that caution should be taken when using hatchery-reared individuals to augment fisheries, even for marine species with high dispersal capacity, and we provide some recommendations to improve hatchery rearing and release practices. Our results further highlight the need to consider the genetic risks of releasing hatchery-reared juveniles into the wild during the establishment of restocking, stock enhancement and sea ranching programs

Genetic considerations on the introduction of farmed fish in marine protected areas: The case of study of white seabream restocking in the Gulf of Castellammare (Southern Tyrrhenian Sea)

Human exploitation has drastically reduced the abundance and distribution of several marine fish and invertebrate populations through overfishing and habitat destruction. Restocking can potentially mitigate these impacts and help to reconstitute depleted stocks but genetic repercussions must be considered. In the present study, the degree of genetic similarity between white seabream (Diplodus sargus Linnaeus 1758) individuals reared for restocking purposes and the receiving population in the Gulf of Castellammare fishery reserve (Sicily, Italy) was assessed using microsatellites. We also inferred the spatial pattern of the genetic structure of D. sargus and connectivity along Sicilian coasts. The farmed population showed significant heterozygosity deficiency in 6 loci and an important reduction in the number of alleles, which could indicate an incipient inbreeding. Both the farmed population and the target one for restocking (Castellammare fishery reserve), showed high and significant values of genetic differentiation due to different allele frequencies, number of privative alleles and total number of alleles. These findings indicate a low degree of genetic similarity between both populations, therefore this restocking initiative is not advisable. The genetic connectivity pattern, highly consistent with oceanographic currents, identified two distinct metapopulations of white seabream around Sicily. Thus it is recommended to utilize broods from the same metapopulation for restocking purposes to provide a better genetic match to the wild populations