Browsing by Author "Presa, Pablo"
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- Conservation of limpet populations: a heavily exploited resource in Azores, NE-AtlanticPublication . Faria, João; Ribeiro, Pedro; Martins, Gustavo M.; Rivas, Manuel; Hawkins, Stephen J.; Presa, Pablo; Neto, Ana I.Limpet harvesting in Azores (NE Atlantic) has been taking place probably since the islands were first colonized in the XV century. Limpet species are highly exploited and populations from most islands have declined steadily bringing about catastrophic effects on coastal communities. Despite their economic importance limpets are also ecologically key species and require prioritizing conservation strategies. Patellid limpets are broadcast spawners which go through a planktonic larval stage in their life cycle. They are benthic as adults and the larva is the only phase during their life-cycle which has the ability to disperse over assumed large spatial distances. However, there is now mounting evidence that gene flow between islands and mainlands can be low, even for species with a relatively long planktonic larval stage. Low levels of larval exchange may thus limit the success of conservation objectives expected upon migration and recruitment. In dispersive isolated oceanic islands such as the Macaronesian Islands, the Azores Archipelago in particular, is not clear whether limpet populations from different islands form a single meta-population or, in contrast, populations on each island are isolated from the rest. Knowledge on this scenario is crucial for the management and conservation of exploited populations of limpets. Here we have developed and described species-specific multiplexed microsatellite markers for the limpets Patella candei and Patella aspera using whole genome shotgun 454 sequencing. These genetic tools have allowed the study of the population genetic structure and evolutionary history of patellid species in the archipelago of Azores. Genetic studies, alongside with biological, ecological and oceanographic information, represent an important contribution for the understanding of population dynamics by allowing testing hypothesis about larval dispersal patterns, recruitment and life history traits, population connectivity, genetic diversity, and population equilibrium.
- Development and characterization of microsattelite Loci for the harvested limpets Patella Candei (D'orbigny, 1839) and Patella Aspera (Röding, 1798) using 454 sequencingPublication . Rivas, Manuel; Faria, João; Ribeiro, Pedro; Presa, Pablo; Martins, Gustavo M.; Neto, Ana I.There is growing consensus that anthropogenic activities are impacting the structure and functioning of marine ecosystems and that these can have profound community level effects, particularly when targeting keystone species. Limpet harvesting in Azores (NE Atlantic) has been taking place probably since the islands were first colonized. These species are highly exploited and the stocks in most islands have declined steadily with catastrophic effects on coastal communities. They are a locally important resource but also ecologically important species and require prioritizing conservation strategies. Such strategies should be su pported by reliable data on the structure and dynamics of their populations, so that ecological hotspots are identified and protected. Characterizing the genetic diversity and structure of marine exploited populations is thus of paramount importance to identify such units of conservation. Here we describe and develop species-specific microsatellite markers for the harvested limpets Patella candei and Patella aspera using whole genome shotgun 454 sequencing. A total of 309 bioinformatic-validated pairs of primers were obtained from P. aspera microsatellite enriched library. The optimization of the amplification conditions of selectect microsatellites (simplex and multiplex reactions) was performed in a gradient thermal cycler to optimize locus-specific amplification conditions and test their utility as genetic markers. Forty pairs of primers were tested, and about 28 revealed to be polymorphic. Using the same procedure, a total of 107 pairs of primers were validated for P. candei of which 15 turned out to be polymorphic. These novel genetic markers can be used to study the population genetic structure and evolutionary history of both patellid species e.g. levels of genetic variability within and between populations, and thus to contribute for stock conservation and management along their distributional area.
- Genetic population structure and connectivity of Azorean limpetsPublication . Faria, João; Presa, Pablo; Martins, Gustavo M.; Ribeiro, Pedro; Neto, Ana I.There is growing consensus that anthropogenic activities significantly rarefy the structure and functioning of marine ecosystems. Oceanic islands such as the Azores (NE Atlantic) constitute unique habitats with fragile communities, which are highly susceptible to degradation and ecosystem disruption. . Patellid limpets have traditionally been collected as a food resource and in 1988 the limpet fishery in São Miguel Island collapsed, and after a one-year ban throughout the archipelago, the stocks were allowed to recover, avoiding catastrophic overexploitation effects. In 1993, legislation was passed to protect this resource, i.e. limpet no-take areas were created, seasonal harvesting restrictions were applied and minimum legal catch sizes were established. However, a recent survey has shown that limpet populations still show clear signs of overexploitation and some populations are virtually extinct in some islands. Here we have developed new multiplexed and described microsatellite markers for the species Patella aspera and P. candei and have examined their genetic diversity, gene flow and population connectivity in the Azores Archipelago. Overall, such information is a fundamental asset to inform conservation strategies and to promote the sustainable exploitation of macaronesian limpets.
- A new multiplexed microsatellite tool for metapopulation studies in the overexploited endemic limpet Patella aspera (Röding, 1798)Publication . Faria, João; Rivas, Manuel; Martins, Gustavo M.; Hawkins, Stephen J.; Ribeiro, Pedro; Pita, Alfonso; Neto, Ana I.; Presa, PabloPatellid limpets are ecologically important keystone grazers having a long history of overexploitation in the Macaronesian Archipelagos (NE Atlantic islands), where some species, such as Patella aspera, are under serious risk.[1, 2] Patella aspera is a protandric sequential hermaphrodite species with external fertilization, in which individuals start off as males but may undergo a sex reversal with age.[3] Hence, exploitation tends to focus on the larger females in the population as larger limpets (predominantly females) are selectively removed. Despite conservation legislation in Canaries, Madeira and Azores, limpets are under severe pressure and few individuals survive long enough to become females, a phenomenon that severely restricts the effective population size.[4] New conservation actions for the protection and sustainable use of limpets in Macaronesian Archipelagos are urgently needed and should be based on a multidisciplinary framework based on knowledge of the population dynamics and connectivity of this species.