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- Modelling spatial and temporal scales for spill-over and biomass exportation from MPAs and their potential for fisheries enhancementPublication . Pérez-Ruzafa, Ángel; Martín, Ernesto; Marcos, Concepción; Zamarro, José Miguel; Stobart, Ben; Harmelin-Vivien, Mireille; Polti, Sandrine; Planes, Serge; García-Charton, José Antonio; González-Wangüemert, MercedesMarine protected areas (MPAs) are considered as a tool for marine conservation and sustainable fishery resource management. Improvements in fishery yields should take place via the spill-over of individuals from the reserve. In general, it has been demonstrated that MPAs affect the density and biomass of the organisms within them, however, little evidence has been found in order to assess the exportation of individuals across their boundaries. In this study, a simple model involving population growth, harvest, and the diffusion coefficient for individuals was used to explore the effects of protection on populations inside the reserve and the spill-over of individuals to the fished area. The model showed that biological responses inside marine reserves appear to develop quickly, reaching mean levels within a short (1–5 year) time period. Mean population abundance is always higher inside the reserve and highlights the effectiveness of protection, particularly when there is strong fishing pressure outside the reserve. However, reserves smaller than 2000 m radius show significantly lower levels of abundance inside than larger sites. Large MPAs (i.e. about 2000 m in radius) offer nearly the maximum capacity for recovery (close to 100% of the system carrying capacity) and nearly the maximum flux of individuals per unit boundary length. Very large MPAs (i.e. larger than 6000 m in radius) could be a guaranteed means of providing resilience in order to prevent population crises, with the added advantage that the flux of individuals is slightly higher at larger distances from the boundary. However, in practice they provide no further advantage towards increasing the density of individuals or the exportation of biomass, and a network of smaller MPAs could be more beneficial, both from the point of view of conservation and of benefits to fisheries.
- Effects of fishing protection on the genetic structure of fish populationsPublication . Pérez-Ruzafa, Ángel; González-Wangüemert, Mercedes; Lenfant, Philippe; Marcos, Concepción; García-Charton, José AntonioMarine reserves have been identified as an important tool in the management of fishery resources and their number is increasing rapidly, most of them being on islands. However, knowledge on the real effect of protection from fishing on the genetic structure of populations, the spatial scales involved, or the suitability of islands as reserves in terms of connectivity, is scarce. This paper analyses the effects of fishery protection on the genetic structure of populations of Diplodus sargus, a target species, in protected and non-protected areas of the western Mediterranean. Populations studied showed high genetic variability at spatial scales from 101 to 103 km. Protected areas have significantly higher allelic richness. The lower levels of heterozygosis and higher heterozygote deficit showed by islands compared with coastal areas makes clear the importance of considering the connectivity processes when designing a MPA.
- The taxonomic status of some Atlanto-Mediterranean species in the subgenus Holothuria (Echinodermata: Holothuroidea: Holothuriidae) based on molecular evidencePublication . Borrero-Pérez, Giomar Helena; Pérez-Ruzafa, Angel; Marcos, Concepción; González-Wangüemert, MercedesMolecular and morphological data were used to evaluate the taxonomic status of the species Holothuria tubulosa Gmelin, 1790, Holothuria stellati Delle Chiaje, 1823, Holothuria mammata Grube, 1840, and Holothuria dakarensis Panning, 1939, belonging to the nominate subgenus Holothuria (Holothuria) (family Holothuriidae) from the Mediterranean Sea and Atlantic Ocean. A 16S rRNA marker distinguished three well-supported clades with clear genetic differentiation amongst them. The morphometric characters, although they reflected the clades, showed great variability, and some specimens from different clades overlapped. The morphological data and the literature suggest that the clades correspond to H. dakarensis (from Cape Verde Islands), H. mammata (from the Atlanto- Mediterranean area) and H. tubulosa (from the Mediterranean Sea). Holothuria stellati is considered here to be a junior subjective synonym of H. tubulosa. Great morphological intraspecific variation within H. tubulosa and H. mammata explains the confusion in the literature. Holothuria tubulosa includes specimens with distinctive ossicles, but others are similar to H. mammata. In these cases, the presence or absence of Cuvierian tubules proved a reliable indicator to the identity of these species; unfortunately this character is difficult to assess in preserved material. According to the results of discriminant analysis we propose a set of ossicle morphometric variables that permit the optimum assignation of individuals to the clades. Our results present a new perspective on the taxonomic status of species in Holothuria (Holothuria), and show how a molecular approach, combined with a morphological approach, can solve taxonomic problems.
- High gene flow promotes the genetic homogeneity of the fish goby Pomatoschistus marmoratus (Risso, 1810) from Mar Menor coastal lagoon and adjacent marine waters (Spain)Publication . Vergara-Chen, Carlos; González-Wangüemert, Mercedes; Marcos, Concepción; Pérez-Ruzafa, ÁngelThe extreme environmental variability of coastal lagoons suggests that physical and ecological factors could contribute to the genetic divergence among populations occurring in lagoon and open-coast environments. In this study we analysed the genetic variability of lagoon and marine samples of the sand goby, Pomatoschistus marmoratus (Risso, 1810) (Pisces: Gobiidae), on the SW Spain coast. A fragment of mitochondrial DNA control region (570 bp) was sequenced for 196 individuals collected in five localities: Lo Pagan, Los Urrutias and Playa Honda (Mar Menor coastal lagoon), and Veneziola and Mazarro´n (Mediterranean Sea). The total haplotype diversity was h = 0.9424 ± 0.0229, and the total nucleotide diversity was p = 0.0108 ± 0.0058. Among-sample genetic differentiation was not significant and small-scale patterns in the distribution of haplotypes were not apparent. Gene flow and dispersal-related life history traits may account for low genetic structure at a small spatial scale. The high genetic diversity found in P. marmoratus increases its potential to adapt to changing conditions of the Mar Menor coastal lagoon.
- Molecular systematics of the genus Holothuria in the Mediterranean and Northeastern Atlantic and a molecular clock for the diversification of the Holothuriidae (Echinodermata: Holothuroidea)Publication . Borrero-Pérez, Giomar Helena; Gómez-Zurita, Jesús; González-Wangüemert, Mercedes; Marcos, Concepción; Pérez-Ruzafa, AngelThis work investigates the systematics of the genus Holothuria in the Mediterranean Sea and Northeastern Atlantic in the light of a wider molecular phylogenetic hypothesis of Holothuriidae, and it also provides a time-scale for the family diversification using mitochondrial markers and the molecular clock hypothesis. The subgenera Holothuria and Roweothuria are retrieved as paraphyletic. At least four separate lineages, with quite different time frameworks were identified. There are at least three species with an apparent long evolutionary history, H. forskali, H. sanctori and H. impatiens and six species belonging to Holothuria, Roweothuria and Vaneyothuria, which have diverged relatively recently.