Browsing by Author "Miranda, Fernando Jorge Veloso"
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- Can invasive alien fish species act as effective hosts of native freshwater mussels (Unionidae) in Iberia?Publication . Teixeira, Amílcar; Dias, Ana Rita; Miranda, Fernando Jorge Veloso; Lopes-Lima, Manuel; Varandas, Simone; Froufe, Elsa; Filipe, Ana Filipa; Beja, Pedro; Sousa, RonaldoThe freshwater biodiversity of Mediterranean areas is severely threatened by several human activities, including habitat loss and fragmentation, river regulation, pollution, overexploitation, climate change and introduction of invasive alien species (IAS). These human disturbances drastically affect native fish and mussel populations and possibly conservation measures are needed to implement to revert major problems. Particularly at risk may be affiliate species such as freshwater mussels (Bivalvia, Unionoida) that have an obligatory parasitic phase of a short-term larval stage on fish host gills and fins. In Iberia, the identification of effective fish hosts for unionid species and the impact of IAS remain unclear. In this study, field and laboratorial studies were performed to assess the fish hosts for Anodonta anatina, Unio delphinus and Potomida littoralis. For in situ monitoring done in Douro basin (Northern Portugal), results showed an effective infestation for native (Luciobarbus bocagei, Squalius carolitertii, Squalius alburnoides and Pseudochondrostoma duriense) but also for non-native (Lepomis gibbosus, Alburnus alburnus, Gambusia holbrooki and Gobio lozanoi) fishes. The highest infestation rate and prevalence were observed for L. bocagei and S. carolitertii, but also for L. gibbosus. However, in laboratorial experiments significant differences were found. In fact, for U. delphinus and P. littoralis only native fishes (mainly endemic cyprinids) showed to be effective hosts, since viable juveniles were produced. A. anatina exhibited a more generalist behavior, with a wide range of native (endemic cyprinids of north and south Iberia) and non-native (Australoheros facetus, Oncorhynchus mykiss, Esox lucius, Phoxinus phoxinus, A. alburnus and G. lozanoi) fish host species. Overall, our results showed: 1) the importance of native fish species for the maintenance of a good conservation status of native unionids; 2) some invasive fish species can also function as hosts of A. anatina and 3) basic ecological data using field monitoring and laboratorial experiments are fundamental to design future conservation measures such as reproduction in captivity and propagation of threatened unionids.
- Ensaio de modelos de gestão silvícola em talhadia de castanheiro: 24 anos de avaliaçãoPublication . Patrício, Maria Sameiro; Nunes, Luís; Iamshchikov, Vladislav; Saraiva, Daniel; Miranda, Fernando Jorge Veloso; Monteiro, Maria do LoretoThe coppice is a very flexible cultural system producing wood of different dimensions. Small-caliber wood formerly with great demand, is now less interesting for the market (although the potential interest for biomass) while the stands have been aging without silvicultural intervention, having as a consequence the degradation of the quality of the wood and the trees health status. It is therefore necessary to improve the management of existing coppices by applying alternative silvicultural models in order to obtain more valuable wood. For this purpose, a trial was established in 1994 consisting of four permanent plots in a coppice that resulted from the final cut of a sweet chestnut high-forest stand in 1992. Three silvicultural management models were tested in order to produce wood of small (P1 = Model 1), medium (P2 = Model 2) and large (P4 = Model 3) dimensions. A control plot was established without any type of silviculture which corresponds to the most of the existing chestnut coppices (P3 = without intervention). Thinnings were applied based on the dominant height growth of the shoots, prescribed in the respective management models, at 7 and 11 years in P1, P2 and P4. The last thinning in plot P4 was applied at age 16 according to Model 3. Twenty four years after the installation, the silvicultural models were evaluated according to their objectives in terms of growth, yield and quality of the wood produced. This evaluation period corresponds to the Model 1 rotation period (final cut planned for an age 25 - 30 years). The results of the application of the silvicultural models are compared with the reference models recommended for wood production. Model 1 presents a dg of about 17 cm and hg of 13 m as well as ddom 23 cm, hdom 15 m and basal area G 30.4 m2 ha-1 being in accordance to the expected values (mean diameter 14-25 cm at 25-30 years). In the plot without intervention the same basal area is obtained (G 30.9 m2 ha-1) but only with a dg of 14.5 cm. From the last thinning at 11 years of age, we observed in P1 4% mortality in stools and 7% in shoots while in P3, plot without intervention, intense competition led to a reduction of 27% in the number of stools and 68% in the number of shoots in relation to the existing density at 11 years. In this plot there is a reduction in the number of stools almost equivalent to that imposed to P1 by thinnings. In plots P2 and P4, no mortality was observed. In Models 2 and 3 the observed growth follows closely the expected for this growth stage of the coppice. The quality of the individual shoots for wood is clearly superior to that of the plot without intervention although the dominant trees may have similar growth rates. Comparing the mean dendrometric values, higher values were observed in plots with the models application. It is verified that the treatment without intervention naturally tends toward to the results of Model 1. The results also show that when the wood is used for saw-timber silvicultural intervention is essential.
- Ensaio de modelos de gestão silvícola em talhadia de castanheiro: 24 anos de avaliaçãoPublication . Patrício, Maria Sameiro; Nunes, Luís; Iamshchikov, Vladislav; Saraiva, Daniel; Miranda, Fernando Jorge Veloso; Monteiro, Maria do LoretoA talhadia é um sistema cultural muito flexível produzindo material lenhoso de diferentes dimensões. As madeiras de pequenos calibres, outrora com grande procura, são hoje pouco procuradas (embora apresentem interesse para biomassa) com os povoamentos a envelhecer sem qualquer intervenção, tendo como consequência a degradação da qualidade do lenho e do estado sanitário dos indivíduos. Assim, é necessário melhorar a gestão das talhadias existentes com a aplicação de modelos silvícolas alternativos no sentido de obter madeira mais valorizada. Com este objetivo instalou-se em 1994 um ensaio composto por 4 parcelas permanentes numa talhadia que resultou do corte de um alto fuste de castanheiro em 1992. Foram consideradas 3 novos modelos de gestão silvícola com o objetivo de testar modelos para produção de madeira de pequenas (P1 = Modelo 1), médias (P2 = Modelo 2) e grandes dimensões (P4 = Modelo 3).Foi estabelecida uma parcela de controlo sem qualquer tipo de silvicultura e que corresponde à maioria das áreas de talhadia de castanheiro existentes (P3 = sem intervenção). Foram aplicados desbastes tendo por base o crescimento em altura dominante das varas, previstos nos respetivos modelos de gestão, aos 7 e 11 anos em P1, P2 e P4. O último desbaste da parcela P4 foi aplicado aos 16 anos de acordo com o Modelo 3. Assim, 24 anos depois da instalação, faz-se a avaliação dos modelos silvícolas aplicados face aos objetivos iniciais em termos de crescimento, produção e qualidade da madeira produzida. Este período de avaliação corresponde ao intervalo de produção do Modelo 1 (corte final previsto aos 25 a 30 anos de idade). Os resultados da aplicação dos modelos silvícolas são comparados com os modelos de referência preconizados para produção de madeira. O Modelo 1 apresenta um dg de cerca de17cm e hg de 13m bem como ddom 23 cm, hdom 15 m e área basal G 30.4 m2 ha-1 estando dentro dos valores esperados (diâmetro médio 14-25 cm aos 25-30 anos). No modelo sem intervenção consegue-se a mesma área basal G 30.9 m2 ha-1 mas apenas com dg aproximado de 14.5 cm. A partir do último desbaste aos 11 anos de idade observamos na P1 uma mortalidade de 4% nas touças e 7% nas varas enquanto na P3,sem intervenção, a intensa competição conduziu a uma redução de 27% no número de touças e 68% no número de varas relativamente à densidade existente aos 11 anos. Nesta parcela verifica-se uma redução no número de varas da mesma ordem de grandeza da imposta à P1 pelos desbastes. Nas parcelas P2 e P4 não se observou mortalidade. Nos Modelos 2 e 3 o crescimento observado acompanha o esperado para esta fase de crescimento da talhadia. A qualidade das varas individuais para madeira é claramente superior à da parcela sem intervenção muito embora as árvores dominantes possam apresentar crescimentos semelhantes. Comparando os valores dendrométricos médios observam-se valores superiores nas parcelas intervencionadas. Verifica-se que o tratamento sem intervenção tende a convergir naturalmente para os resultados do Modelo 1, contudo os resultados também mostram que quando se pretende a valorização do material lenhoso para serração a intervenção silvícola é essencial.
- Importância da pesca lúdica e desportiva no Nordeste TransmontanoPublication . Miranda, Fernando Jorge Veloso; Teixeira, AmílcarNo ano de 2012, foi feita uma caraterização da pesca lúdica e desportiva do Nordeste Transmontano, baseada num universo de 120 inquéritos realizados a pescadores entrevistados maioritariamente nas bacias hidrográficas dos rios Sabor e Tua. Foram obtidas informações relevantes, como o perfil, preferência pelo tipo de massa hídrica, frequências de viagens, motivação, gastos despendidos, interesse em competições, vigilância e legislação existente. Nesta região do norte de Portugal, os pescadores revelaram preferência por espécies autóctones, com especial predominância pela truta, e ainda pelo barbo, boga e escalo, mas também se verificou um aumento do interesse na pesca ao achigã e ao lúcio, de introdução relativamente recente. Foram ainda identificadas pressões sobre os recursos piscícolas resultantes da sobrepesca, poluição, regularização e degradação das galerias ripícolas. Surgiram também indicações acerca da necessidade de comunicação entre pescadores, serviços estatais e investigação e ainda do envolvimento do público e dos media, através do desenvolvimento de diferentes ações de informação, sensibilização e educação. Tendo em conta a baixa produtividade piscícola que caracteriza as águas oligotróficas dos rios do Nordeste de Portugal, é sugerida a necessidade de evolução para: 1) técnicas de pesca sem morte (i.e. catch and release); 2) uso exclusivo de iscos artificiais; 3) criação de zonas de proteção adequadas; 4) criação de parques de pesca; 5) aplicação de técnicas de melhoria do habitat em zonas degradadas; 6) melhor gestão das zonas concessionadas; 7) medidas legislativas apropriadas; 8) melhor gestão e ordenamento das massas hídricas. Importa ainda realçar que as albufeiras dos Aproveitamentos Hidroelétricos do Baixo Sabor (AHBS) e de Foz Tua (AHFT) poderão, num futuro próximo, atrair muitos pescadores não residentes, de Portugal, Espanha e outros países, e potenciar os benefícios diretos (e.g. nº de licenças, equipamentos) e indiretos (e.g. restauração, alojamento) associados à pesca na região.
- Invasive dynamics of the signal crayfish Pacifastacus leniusculus in a protected areaPublication . Carvalho, Francisco; Alves, Henrique; Pascoal, Cláudia; Castro, Paulo; Miranda, Fernando Jorge Veloso; Teixeira, Amílcar; Cássio, Fernanda; Sousa, RonaldoInvasive species have been drivers of biodiversity loss and functional changes in aquatic ecosystems, including in protected areas. Therefore, monitoring population invasion dynamics and biological traits is fundamental to better understand their ecological and economic impacts and for management actions development. We followed signal crayfish (Pacifastacus leniusculus) invasion in Rabaçal River upper reach at Montesinho Natural Park, Portugal. We collected information on the spread and biological traits (abundance, size, weight, physical condition, sex ratio, and aggressiveness) to assess differences between invasion core and front areas and among years. Signal crayfish population remained restricted since first reports in 2013 in the invasion core until 2017. After 2019, signal crayfish population has been spreading downstream, decreasing abundance at invasion core but increasing at invasion front. Significant higher number of crayfish with claw loss indicate potential higher signs of aggressiveness in the invasion front. Results also demonstrate a significant dominance of females although sex ratio is closer to 1:1 at the invasion front. Overall, results indicate signal crayfish is spreading and increasing their abundance at Rabaçal River highlighting the need for immediate management actions to hold dispersion and mitigate possible impacts.
- A pesca lúdica e desportiva no Nordeste Transmontano (Bacia do Douro, Portugal)Publication . Miranda, Fernando Jorge Veloso; Teixeira, AmílcarHá muito que o Homem usufrui e explora os recursos associados aos ecossistemas aquáticos. Muitas vezes esta exploração de recursos aquícolas, entre os quais a pesca assume vital importância, é feita indiscriminadamente, fazendo com que o próprio homem se debruce sobre a problemática da sustentabilidade de populações e comunidades piscícolas. Foi nesta perspetiva e com o intuito de contribuir para a formulação das melhores ações de gestão e ordenamento dos recursos aquícolas que se recorreu ao testemunho dos pescadores desportivos da região, a fim de obter informação da sua atividade piscatória através da realização de inquéritos. Desta forma, a partir dum universo de 100 inquiridos, foram caraterizados diversos aspetos ligados à pesca lúdica e desportiva (tendo em conta a atividade desenvolvida nos anos de 2011 e 2012): perfil dos pescadores, preferências pelo tipo de massa hídrica, frequências de viagens, motivação, gastos despendidos, espécies capturadas, participação em competições, vigilância e legislação existente e abordagens complementares, como a formação e educação ambiental e a necessidade de repensar a pesca na região. Os resultados obtidos reforçam a necessidade de mais organização e especialmente comunicação entre todos os utilizadores, nomeadamente pescadores, serviços estatais e investigação. De forma complementar, foram realizados inventários piscícolas para atualização da distribuição de espécies piscícolas na rede hídrica, e evolução do ratio entre espécies autóctones e exóticas, cuja expansão tem sido evidente nas últimas décadas. Foram selecionados 28 locais de amostragem nas bacias dos rios Sabor e Tua que mostraram a boa qualidade biológica patente nos setores superiores, i.e. uma presença quase exclusiva de peixes autóctones (e.g. truta, barbo, boga, bordalo). Por outro lado, os setores médios e inferiores ao acumular diferentes impactos de natureza antrópica facilitam a invasão e estabelecimento de espécies alienígenas (e.g. perca-sol, achigã, lúcio, lucioperca). No futuro próximo, os Aproveitamentos Hidroelétricos do Baixo Sabor e de Foz Tua, com a criação de extensas albufeiras, vão criar novas oportunidades para a pesca desportiva, justificando a definição de planos estratégicos para a gestão eficiente dos recursos da região. No entanto, a contenção e mitigação de impactos é fundamental para a preservação de setores de boa integridade ecológica, precisamente nos setores superiores onde não só a truta, como os ciprinídeos endémicos, são um recurso valioso em temos da pesca lúdica e desportiva, mas essencialmente em termos de conservação. Como técnica de gestão piscícola realizaram-se ainda repovoamentos de truta na ribeira de S. Cibrão, curso de água de montanha da bacia do Tua, onde as populações nativas tinham desaparecido, com baixo sucesso nos resultados obtidos. T
- Setting the stage for new ecological indicator species: a holistic case study on the Iberian dolphin freshwater mussel Unio delphinus Spengler, 1793Publication . Lopes-Lima, Manuel; Hinzmann, Mariana; Varandas, Simone; Froufe, Elsa; Reis, Joaquim; Moreira, Cláudia; Araújo, Sandra; Miranda, Fernando Jorge Veloso; Gonçalves, Duarte V.; Beja, Pedro; Sousa, Ronaldo; Teixeira, AmílcarDue to their sensitivity and dramatic declines, freshwater mussels are prime targets for conservation and environmental monitoring. For this, however, information is needed on life history and ecological traits, which is lacking in many taxa, including threatened species. Species recently described or recognized as valid are of particular concern, due to the shortage of even basic knowledge. A case in point is the recently recognized and Near Threatened dolphin freshwater mussel Unio delphinus Spengler, 1793, which is endemic to the western Iberian Peninsula and has suffered marked population declines. To overcome information gaps for U. delphinus, we carried out a holistic biological study across the species range, aiming to: i) estimate the area of occupancy (AOO) and extent of occurrence (EOO) based on updated distribution data taken from the literature and recent surveys; ii) estimate growth patterns from biometrical (shell dimensions and growth annuli) measurements taken on specimens from seven populations; iii) estimate sex ratios from gonad tissue biopsies collected on specimens from eight populations; iv) estimate gametogenesis and sex ratio through histological examination of gonad and gill tissues collected monthly for a year, from a single population; and v) determine host species from infestation trials of glochidia with co-occurring fish species. We estimated an EOO of 706 km2 and an AOO of 61 km2, which together with data on declines assigns the species to the Endangered category using IUCN criteria. Unio delphinus was found to grow faster and to be shorter-lived (up to 11 years, maturity at around 2 years old) than other European freshwater mussels. Growth and life span are similar across the range in lotic habitats, but different from that in lentic habitats. The larvae of U. delphinus may attach to most co-occurring fish species, but only native species were effective hosts. Native cyprinids, especially those from the genus Squalius, seem to be the primary hosts. Overall, the information provided contributes to a better conservation status assessment, selection of conservation and rehabilitation areas, guidance for the establishment of propagation programs and better timing for specimens’ manipulation including monitoring and possible translocations. The framework presented here highlights the importance of basic biological studies to define good ecological and physiological status.
- The silent extinction of freshwater mussels in PortugalPublication . Lopes-Lima, Manuel; Reis, Joaquim; Alvarez, Maria G.; Anastácio, Pedro M.; Banha, Filipe; Beja, Pedro; Castro, Paulo S.; Gama, Mafalda; Gil, Maria G.; Gomes-dos-Santos, André; Miranda, Fernando Jorge Veloso; Nogueira, Joana Garrido; Sousa, Ronaldo; Teixeira, Amílcar; Varandas, Simone; Froufe, ElsaFreshwater mussels are one of the most threatened animal groups in the world. In the European Union, threatened and protected mussel species are not adequately monitored, while species considered to be common and widespread receive even less attention. This is particularly worrying in the Mediterranean region, where species endemism is high and freshwater habitats are severely affected by water scarcity. In the absence of hard data on population trends, we report here a long-term comparison of freshwater mussel assemblages at 132 sites covering 15 different hydrological basins in Portugal. This study reveals a widespread decline of 60 % in the number of sites and 67 % in the overall abundance of freshwater mussels across Portugal over the last 20 years, indicating that all species are rapidly declining and threatened with extinction. These results show that current legislation and conservation measures are largely ineffective and highlight the importance of updating the Habitats Directive to enforce standard monitoring protocols for threatened species in the European Union and to extend monitoring to other freshwater species thought to be common and widespread. Efficient water management, restrictions on irrigation expansion in important biodiversity areas, mitigation of hydrological changes and loss of aquatic habitat connectivity caused by physical alterations are urgently needed to reverse these declining population trends. For the severely endangered species Margaritifera margaritifera, Potomida littoralis, and Unio tumidiformis, where populations are now critically low, more urgent action is needed, such as ex-situ conservation, protection of remaining populations and large-scale habitat restoration.
- Threatened fish and mussel populations in Douro basin (Northern Portugal): in-situ and ex-situ conservation measuresPublication . Teixeira, Amilcar; Froufe, Elsa; Varandas, Simone; Sousa, Ronaldo; Miranda, Fernando Jorge Veloso; Inssi, Hanane; Lopes-Lima, ManuelFreshwater ecosystems are threatened by human activities and their biodiversity declines far greater than those on marine and terrestrial ecosystems. Severa! impacts such as habitat loss and fragmentation, pollution, river regulation, overexploitation, introduction ofinvasive species and envoronmental changes are responsible for increasing the extinction risk ofnative species and for the dismption of important ecosystem functions and services. Freshwater mussels (Bivalvia: Unionoida) are among the most threatened faunistic groups in these freshwater ecosystems. These mussels depend on fish to complete their life cycle, where mussel larvae use a specific range of fish hosts to metamorphose. Therefore, the persistence of freshwater mussel species will ultimately depend on the conservation oftheir físh hosts. The Iberian Península holds a high levei ofspatially restricted species and endemisms. Many native físh and mussel species oflberia are listed as vulnerable, endangered or critically endangered and their populations are declining. In this study, we will use data collected in the last 5 years in the main tributaries ofRiver Douro in Portugal to assess the conservation status of native freshwater mussel and fish species and, in particular, the impact of environmental changes. Despite the low human density in three basins (Sabor, Tâmega and Tua), some river stretches are suffering of habitat loss and degradation. Furthermore, the increase in intensity and magnitude of extreme climatic events are inducing higher mortality rates in fish and mussel populations. There are reports of massive die-offs of mussel populations due to a succession of irregular drought and fíood events. For ali these reasons, several in-situ and ex-situ conservation measures have been developed to protect endangered native species ofNE Portugal. In addition, other actions were oriented to the training and public awareness for the conservation ofthreatened species and habitais.
- Time travelling through local ecological knowledge regarding an endangered speciesPublication . Sousa, Ronaldo; Nogueira, Joana Garrido; Miranda, Fernando Jorge Veloso; Teixeira, AmílcarEuropean freshwater pearl mussel (Margaritifera margaritifera) populations are declining despite a growing effort to conserve them. Here we used a combination of local ecological knowledge (LEK) and field sampling to assess past and current distribution and conservation status of this endangered species in Cávado and Neiva Rivers (Portugal). We performed face-to-face interviews in both rivers and sampled the entire area where the respondents confirmed the historical presence of this species. Abiotic characterization, water quality and fish diversity were also assessed in both rivers. We found that freshwater pearl mussels are now possibly extinct in Cávado River but almost 50% of the respondents confirm its presence in the past, especially elders that lived in villages near its historical distribution. To the contrary, and although the species is still present in Neiva River, only 3.8% of the respondents remembered its presence in the past. In both rivers, respondents suggested pollution as the most important explanation for the freshwater pearl mussels decline. However, nowadays both rivers present excellent water quality and trout Salmo trutta (the freshwater pearl mussel fish host) is still abundant. Since we identified the areas where the species was present in a recent past, this information is vital for possible management actions with the aim of re-introduce or increase the abundance of M. margaritifera populations and/or for the rehabilitation of habitats in both rivers. We also highlight the vital importance of getting LEK, mainly from elders, in order to avoid shifting baseline syndromes and to get qualitative accurate information of past references and/or experience with historical conditions. Results reported here reinforce concern about the conservation status of freshwater pearl mussel populations in Portugal and can be used to guide future research and management initiatives to better conserve this species.