Browsing by Author "Valente, Sara"
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- Effects of fishery protection on biometry and genetic structure of two target sea cucumber species from the Mediterranean SeaPublication . Gonzalez-Wangueemert, Mercedes; Valente, Sara; Aydin, MehmetSea cucumber fisheries are now occurring in most of the tropical areas of the world, having expanded from its origin in the central Indo-Pacific. Due to the overexploitation of these resources and the increasing demand from Asian countries, new target species from Mediterranean Sea and northeastern Atlantic Ocean are being caught. The fishery effects on biometry and genetic structure of two target species (Holothuria polii and H. tubulosa) from Turkey, were assessed. The heaviest and largest individuals of H. polii were found into the non-fishery area of Kusadasi, also showing the highest genetic diversity. Similar pattern was detected in H. tubulosa, but only the weight was significantly higher in the protected area. However, the observed differences on the fishery effects between species, could be explained considering the different percentage of catches (80% for H. polii and 20% for H. tubulosa).
- Genetic diversity across geographical scales in marine coastal ecosystems: Holothuria arguinensis a model speciesPublication . Rodrigues, F.; Valente, Sara; Gonzalez-Wanguemert, MercedesCoastal lagoons are considered one of the most productive areas of our planet harboring a large variety of habitats. Their transitional character, between terrestrial and marine environments, creates a very particular ecosystem with important variations of its environmental conditions. The organisms that are able to survive on these ecosystems frequently experience strong selective pressures and constrictions to gene flowwith marine populations, which could contribute to genetic divergence among populations inhabiting coastal lagoon and marine environments. Therefore, the main aims of this study are to asses the genetic diversity and population structure of Holothuria arguinensis across geographical ranges, to test the hypothesis of coastal lagoons as hotspots of genetic diversity in the Ria Formosa lagoon, and to determine the role of exporting standing genetic variation from the lagoon to open sea and their implications to recent geographical expansion events. To reach these objectives, we investigate the genetic structure of H. arguinensis using two mitochondrial DNA markers (COI and 16S) at different spatial scales: i) small, inside Ria Formosa coastal lagoon, South Portugal; 2) large, including most of the geographical distribution of this species (South and Western Portuguese coast and Canary islands); these results will allow us to compare the genetic diversity of lagoonal and marine populations of H. arguinensis. On this framework, its recent geographical expansion events, recorded by Rodrigues (2012) and González-Wangüemert and Borrero-Pérez (2012), will be analyzed considering the potential contribution from lagoonal genetic pool. Non-significant genetic structure and high haplotypic diversity were found inside the Ria Formosa coastal lagoon. Both genes were unable to detect significant genetic differentiation among lagoonal and marine localities, suggesting a high rate of gene flow. The results supported our hypotheses that coastal lagoons are not only acting as hotspots of genetic diversity, but also contributing for the genetic variability of the species, working as a source of new haplotypes and enhancing adaptation to the high variable conditions. Different genetic patterns of colonization were found on H. arguinensis, but they must be studied more deeply.
- Setting preliminary biometric baselines for new target sea cucumbers species of the NE Atlantic and Mediterranean fisheriesPublication . González-Wangüemert, Mercedes; Valente, Sara; Henriques, Filipe; Domínguez-Godino, Jorge A.; Serrao, EsterCommercial interest on sea cucumber species from the NE Atlantic and the Mediterranean is increasing.Holothuria polii, Holothuria tubulosa, Holothuria mammata and Holothuria arguinensis are the new targetspecies. The scarce biological and ecological knowledge on these species along their geographical distri-bution, is a major problem for their fisheries management. To address it, we carried out a morphometricstudy to describe the baseline population size structure, focused on the length–weight relationship andsize–weight distribution.In the NE Atlantic, the largest mean size and heaviest mean weight of H. mammata and H. arguinensiswere found in localities with upwelling, but another factors could be influencing on these results. In theMediterranean, Girona and Mallorca showed the heaviest specimens of H. polii, H. tubulosa and H. mam-mata, and the smallest were registered in Crete and Kusadasi. Significant differences in length and weightbetween populations were found for each species. These results could be linked with local environmentalconditions. Size frequency distribution was multimodal for all species except for H. mammata; the weightfrequency distribution was only unimodal for H. polii and H. mammata.This study provides novel data, helpful for stock and population assessment which could support theimplementation of effective management for the European sea cucumber target species.
- West versus East Mediterranean Sea: origin and genetic differentiation of the sea cucumber Holothuria poliiPublication . Valente, Sara; Serrão, Ester; Gonzalez-Wangueemert, MercedesWe studied the genetic structure of the sea cucumber Holothuria (Roweothuria) polii (Delle Chiaje 1823) by analysing the mitochondrial DNA variation in two fragments of cytochrome oxidase I (COI) and 16S genes. Individuals were collected in seven locations along the Mediterranean Sea, which cover a wide range of the species distribution. We found high haplotype diversity for COI and moderate diversity for 16S, and low nucleotide diversity for both genes. Our results for the COI gene showed many recent and exclusive haplotypes with few mutational changes, suggesting recent or ongoing population expansion. The Western and Eastern Mediterranean populations exhibited slight but significant genetic differentiation (COI gene) with higher genetic diversity in the East. The most ancient haplotype was not present in the westernmost sampling location (SE Spain). The oldest expansion time was observed in Turkey, corresponding to mid-Pleistocene. Turkey had also the highest genetic diversity (number of total and exclusive haplotypes, polymorphisms, haplotype and nucleotide diversity). This suggests that this region could be the origin of the subsequent colonizations through the Mediterranean Sea, a hypothesis that should be assessed with nuclear markers in future research.