Browsing by Author "Martins, Gustavo M."
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- Are seawalls made of natural substrata better?Publication . Valentim, Ana L.; Martins, Gustavo M.; Neto, Ana I.
- Avaliação do stock de Abalones: uma pesca sustentávelPublication . Prestes, Afonso L.; Neto, Ana I.; Rodrigues, Armindo; Martins, Gustavo M.A falta de informação anterior ao início de uma exploração de uma espécie alvo é ponto comum à maior parte das pescarias. A maioria dos estudos só é iniciada após indícios claros de efeitos de um excesso de pesca. No entanto, esta situação é indicadora de que a pesca já causou alterações drásticas na estrutura das populações alvo e que, consequentemente, já não existe um ponto de referência que informe a gestão e a recuperação dos mananciais. A exploração do abalone nos Açores é virtualmente inexistente, ao contrário de muitas outras regiões onde a sua captura tem levado à ruptura dos mananciais. A espécie existente nos Açores, Haliotis tuberculata, é um recurso com elevado interesse gastronómico e económico e existem indícios de que tem sido gradualmente introduzida na gastronomia regional. Nos Açores os mananciais de H. tuberculata podem, à partida, ser considerados virgens, mas não existe informação sobre a sua abundância, biologia e ecologia. Concomitantemente, não existe qualquer tipo de restrição ou legislação regional relativamente à exploração deste marisco. O presente projecto tem como objectivo avaliar o estado actual das populações de H. tuberculata providenciando um ponto de referência para estudos futuros e garantindo deste modo uma avaliação rigorosa dos impactos de uma potencial pescaria. Neste projecto examinam-se aspectos da biologia e da ecologia de H. tuberculata que providenciarão dados úteis para garantir uma exploração sustentável deste recurso. O presente estudo providenciará também recomendações para a gestão desta pescaria baseadas na revisão bibliográfica e na informação recolhida.
- The Azorean edible abalone Haliotis tuberculata, an alternative heavy metal-free marine resource?Publication . Torres, Paulo; Rodrigues, Armindo; Prestes, Afonso L.; Neto, Ana I.; Álvaro, Nuno V.; Martins, Gustavo M.Abalones are considered a delicacy and exploited for food worldwide. In many places, overfishing has led to the decimation of wild stocks and many are now reared in aquaculture systems. In the Azores, there is no tradition of eating abalones and Haliotis tuberculata stocks are still virtually untouched. However, as tourism in the islands grows and the stocks of other shellfish diminish, there is an increasing pressure to find alternative edible resources, leading to a rising interest in abalones. According to previous studies performed in the region, other edible species, including the local highly appreciated limpets and the giant barnacle, present high concentration levels of some heavy metals, which has been attributed to the volcanic origin of the islands. Here we analysed the metal content in the edible tissue of Haliotis tuberculata from São Miguel Island, Azores. The potential human health risks due to its consumption was assessed by estimating the average daily intake (EDI) and target hazard quotient (THQ) of metals. Similarly to other organisms in the Azores, abalones have higher than normal levels of some heavy metals, particularly cadmium, reflecting a local natural source that should be closely monitored from a public health point of view.
- Bioavailable metals and cellular effects in the digestive gland of marine limpets living close to shallow water hydrothermal vents.Publication . Cunha, Luís; Amaral, André; Medeiros, Vera; Martins, Gustavo M.; Wallenstein, Francisco; Couto, Ruben P.; Neto, Ana I.; Rodrigues, ArmindoThe pressure exerted by shallow water hydrothermal vents on edible gastropods and their cellular responses triggered by these stresses are almost unknown. The aims of this study were to evaluate the bioavailability of metals in the Macaronesian endemic limpet Patella candei gomesii living close to shallow water hydrothermal vents, and the structural differences in their digestive gland as well as the levels of apoptosis in that organ. Limpets were sampled in four sites, two with the presence of hydrothermalism and the other two without it. Whole body concentrations of several metals (Ca, Cd, Cs, Co, Cu, Fe, Hg, Mg, Mn, Pb, Rb, Se, Sr, and Zn) were obtained, morphometry analysis of the digestive gland and TUNEL test for apoptosis were also performed. Results revealed that the presence of shallow water hydrothermal vents is a source of chronic metal stress to limpets, imposing modifications in the morphometry and cell composition of the digestive gland of those limpets that may constitute cell and tissue adaptations to the environment they live in. This study sets up new baseline data for further research on the influence of shallow water hydrothermal vents over communities living in these habitats.
- A case of simultaneous hermaphroditism in the Azorean endemic limpet Patella candei gomesii (Mollusca: Patellogastropoda), a gonochoristic speciesPublication . Cunha, Luís; Martins, Gustavo M.; Amaral, André; Rodrigues, ArmindoA case of simultaneous hermaphroditism was observed in Patella candei gomesii, an Azorean endemic species, which has been considered a gonochoristic species. Here we show that simultaneous hermaphroditism can occur within the family Patellidae.
- 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.
- Differences in the structure and functioning of two communities : frondose and turf-forming macroalgal dominated habitatsPublication . Martins, Gustavo M.; Hipólito, Cláudia; Parreira, Filipe; Prestes, Afonso L.; Dionísio, Maria Ana; Azevedo, José M. N.; Neto, Ana I.In many coastal regions, vegetated habitats (e.g. kelps forests, seagrass beds) play a key role in the structure and functioning of shallow subtidal reef ecosystems, by modifying local environmental conditions and by providing food and habitat for a wide range of organisms. In some regions of the world, however, such idiosyncratic ecosystems are largely absent and are often replaced by less notable ecosystem formers. In the present study, we empirically compared the structure and functioning of two distinct shallow-water habitats present in the Azores: one dominated by smaller frondose brown macroalgae (Dictyotaceae and Halopteris) and one dominated by low-lying turfs. Two replicated areas of each habitat were sampled at two different times of the year, to assess spatial and temporal consistency of results. Habitats dominated by small fronds were significantly (ca. 3 times) more productive (when standardized per algal mass) compared to the turf-dominated habitats, and supported a distinct assemblage (both in terms of composition and abundance) of associated macrofauna. Unlike other well-known and studied vegetated habitats (i.e. kelp forests), however, no effects of habitat were found on the structure of benthonic fish assemblages. Results were spatially and temporally consistent suggesting that, in warmer temperate oceans, habitats dominated by species of smaller frondose brown algae can also play an important role in the structure and functioning of subtidal communities and may, to a certain extent, be considered analogous to other well-known vegetated habitats around the world (i.e. kelp forests, seagrass beds).
- Do man-made habitats affect spatial patterns of mollusk abundance?Publication . Cacabelos, Eva; Martins, Gustavo M.; Sánchez, Rocío; Busquier, Laura; Mosquera, Rubén; Neto, Ana I.The fragmentation of natural habitats, together with its loss, is considered a major threat to biodiversity. Man-made habitats, e.g., seawalls and coastal defence structures, are a common feature causing the fragmentation on the shoreline of many urbanized coastal areas and will become more widespread in response to rising and stormier seas. Fragmentation can alter functional connectivity of habitats and determine the spatial distribution of organisms, since the movement and dispersal of individuals can be interrupted. However, ecological consequences of coastal defence structures have not been extensively studied and we know little about their effects in marine systems. One of the most important factors affecting the connectivity among fragments or patches is the ability of the organisms to disperse despite potential barriers. Spatial patterns of molluscs with planktonic larvae or direct development (non-planktotrophic larvae) has been compared before, but there is a growing interest to understand the role of the man-made habitats in determining the patterns of spatial abundances of marine organisms. This study was aimed at exploring the role of type of larval development (planktotrophic vs non-planktotrophic) on patterns of spatial variation of gastropods on rocky shores, elucidating the possible responsibility of habitat fragmentation in observed patterns (i.e. seawall presence). Strongly aggregated distribution patterns are supposed to be characteristic of organisms with direct development, while the existence of planktotrophic larvae could allow the homogeneous distribution of organisms with indirect development. We examined the distribution patterns of grazing molluscs with both planktotrophic (the gastropods Tectarius striatus and Melaraphe neritoides) and direct (e.g. Omalogyra atomus or Lasaea adansoni) development in continuous rocky shores, natural patches and fragments. Two natural rocky shores of each type (continuous rocky shores, natural patches and fragments), separated from each other by kms, were sampled. At the mid-intertidal level, the gastropods Tectarius striatus and Melaraphe neritoides were identified and quantified in situ in quadrats randomly deployed on the shore. Randomly replicates of seaweed turfs, composed mostly by articulated coralline algae, were collected in the chosen locations and target gastropods were sorted and quantified in the laboratory. We predict that organisms with planktotrophic development will be less affected by fragmentation because they have the ability to disperse among fragments.
- Dramatic changes in the structure of shallow-water marine benthic communities following the invasion by Rugulopteryx okamurae (Dictyotales, Ochrophyta) in Azores (NE Atlantic)Publication . Faria, João; Prestes, Afonso L.; Moreu, Ignacio; Cacabelos, Eva; Martins, Gustavo M.Biological invasions are considered one of the most important drivers of biodiversity loss. Here we use a before-after-control-impact (BACI) design to investigate the impact of Rugulopteryx okamurae on the structure of shallow-water marine benthic communities in São Miguel island, Azores. After its first appearance in 2019, R. okamurae has rapidly invaded much of the southern coast of the island, where it became the dominant algae. This was followed by significant changes in the structure of shallow-water marine benthic communities, with substantial losses of natural variability and species richness. Compared to before, there has been dramatic reductions in the abundances of articulated coralline algae, corticated algae and corticated foliose algae in invaded locations. These results highlight its highly invasive character, not seen with other, more well-known, invasive species. It remains to be investigated if its impacts persist throughout time and to quantify the functional consequences of such dramatic changes.