Browsing by Author "Sousa, Ronaldo"
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- Alarming decline of freshwater trigger species in western Mediterranean key biodiversity areasPublication . Nogueira, Joana Garrido; Sousa, Ronaldo; Benaissa, Hassan; De Knijf, Geert; Ferreira, Sónia; Ghamizi, Mohamed; Gonçalves, Duarte V.; Lansdown, Richard; Numa, Catherine; Prié, Vincent; Riccardi, Nicoletta; Seddon, Mary; UrbaÅ„ska, Maria; Valentini, Alice; Vikhrev, Ilya; Varandas, Simone; Teixeira, Amílcar; Lopes-Lima, Manuel; Nogueira J.G.Theidentification of key biodiversity areas (KBA) was initiated by the International Union for Conservation of Nature in 2004 to overcome taxonomic biases in the selection of important areas for conservation, including freshwater ecosystems. Since then, several KBAs have been identified mainly based on the presence of trigger species (i.e., species that trigger either the vulnerability and or the irreplaceability criterion and thus identify a site as a KBA). However, to our knowledge, many of these KBAs have not been validated. Therefore, classical surveys of the taxa used to identify freshwater KBAs (fishes, molluscs, odonates, and aquatic plants) were conducted in Douro (Iberian Peninsula) and Sebou (Morocco) River basins in the Mediterranean Biodiversity Hotspot. Environmental DNA analyses were undertaken in the Moroccan KBAs. There was a mismatch between the supposed and actual presence of trigger species. None of the trigger species were found in 43% and 50% of all KBAs surveyed in the Douro and Sebou basins, respectively. Shortcomings of freshwater KBA identification relate to flawed or lack of distribution data for trigger species. This situation results from a misleading initial identification of KBAs based on poor (or even inaccurate) ecological information or due to increased human disturbance between initial KBA identification and the present. To improve identification of future freshwater KBAs, we suggest selecting trigger species with a more conservative approach; use of local expert knowledge and digital data (to assess habitat quality, species distribution, and potential threats); consideration of the subcatchment when delineating KBAs boundaries; thoughtful consideration of terrestrial special areas for conservation limits; and periodic field validation.
- Alarming decline of freshwater trigger species in western Mediterranean key biodiversity areasPublication . Nogueira, Joana Garrido; Sousa, Ronaldo; Benaissa, Hassan; De Knijf, Geert; Ferreira, Sónia; Ghamizi, Mohamed; Gonçalves, Duarte V.; Lansdown, Richard; Numa, Catherine; Prié, Vincent; Riccardi, Nicoletta; Seddon, Mary; Urbańska, Maria; Valentini, Alice; Vikhrev, Ilya; Varandas, Simone; Teixeira, Amílcar; Lopes‐Lima, ManuelThe identification of key biodiversity areas (KBA) was initiated by the International Union for Conservation of Nature in 2004 to overcome taxonomic biases in the selection of important areas for conservation, including freshwater ecosystems. Since then, several KBAs have been identified mainly based on the presence of trigger species (i.e., species that trigger either the vulnerability and or the irreplaceability criterion and thus identify a site as a KBA). However, to our knowledge, many of these KBAs have not been validated. Therefore, classical surveys of the taxa used to identify freshwater KBAs (fishes, molluscs, odonates, and aquatic plants) were conducted in Douro (Iberian Peninsula) and Sebou (Morocco) River basins in the Mediterranean Biodiversity Hotspot. Environmental DNA analyses were undertaken in the Moroccan KBAs. There was a mismatch between the supposed and actual presence of trigger species. None of the trigger species were found in 43% and 50% of all KBAs surveyed in the Douro and Sebou basins, respectively. Shortcomings of freshwater KBA identification relate to flawed or lack of distribution data for trigger species. This situation results from a misleading initial identification of KBAs based on poor (or even inaccurate) ecological information or due to increased human disturbance between initial KBA identification and the present. To improve identification of future freshwater KBAs, we suggest selecting trigger species with a more conservative approach; use of local expert knowledge and digital data (to assess habitat quality, species distribution, and potential threats); consideration of the subcatchment when delineating KBAs boundaries; thoughtful consideration of terrestrial special areas for conservation limits; and periodic field validation.
- Assessment of a terrestrial protected area for the conservation of freshwater biodiversityPublication . Nogueira, Joana Garrido; Teixeira, Amílcar; Varandas, Simone; Lopes-Lima, Manuel; Sousa, RonaldoFreshwater ecosystems are essential to human well-being and most have high biodiversity. However, this biodiversity has been suffering severe declines owing to the expansion of human activities. Protected areas (PAs) are essential for biodiversity conservation and have proved to be successful in stopping species extirpation if managed properly. Unfortunately, they are usually focused on terrestrial biodiversity, leaving freshwater ecosystems aside. The main goal of this study was to determine the influence of a PA (Montesinho Natural Park (MNP), Portugal) on freshwater biodiversity. Aquatic macroinvertebrates and fishes were surveyed, and biodiversity (richness, abundance, Shannon-Wiener diversity, and Pielou's evenness) and water quality (IASPT) indices were calculated inside, at the periphery and outside the MNP. Results showed that the PA does not affect positively either water quality or the two faunal groups monitored. Macroinvertebrate communities were not influenced by the PA; however, the abundance of pearl mussel Margaritifera margaritifera was significantly higher and size was significantly lower inside the MNP. The richness and abundance of fish communities were significantly higher outside the MNP, except for trout Salmo trutta abundance which was higher inside the MNP. Given these results, the MNP does not guarantee the safeguard of overall aquatic biodiversity and habitats and we propose an extension of MNP to downstream areas in order to increase the number of species (mostly cyprinids) under legal protection. This work demonstrates that terrestrial PA planning and management should also consider aquatic biodiversity to achieve successful conservation.
- Bioecologia dos mexilhões de água doce (Unionidae) nos rios Sabor, Tua e Tâmega (Bacia do Douro, Portugal): principais ameaças e medidas de conservaçãoPublication . Teixeira, Amílcar; Varandas, Simone; Sousa, Ronaldo; Froufe, Elsa; Lopes-Lima, ManuelForam avaliadas as condições ambientais das populações de náiades (Mollusca, Bivalvia, Unionidae) em diferentes troços dos rios Tâmega, Tua e Sabor, na proximidade de grandes empreendimentos hidroelétricos em fase de construção. No verão dos anos 2010, 2011 e 2012 foi caracterizado o habitat e microhabitat disponível e usado pelas espécies Unio delphinus, Anodonta anatina e Potomida littoralis. Recorreu-se à metodologia do River Habitat Survey (RHS) para a avaliação do habitat aquático e ribeirinho. Para avaliação do microhabitat, foram realizados transectos paralelos (próximo das margens) e perpendiculares ao fluxo de água. Em cada microhabitat amostrado (0,25 m2) procedeu-se à medição das variáveis profundidade, substrato dominante, velocidade no leito e coluna de água, cobertura e distância à margem. Os unionídeos demonstraram uma distribuição espacial agregada em zonas específicas, tendo-se detetado densidades superiores na proximidade das margens e especialmente em braços laterais dos rios com fluxo permanente de água. Foram construídas curvas de preferência para cada espécie. Assim, Unio delphinus e Anodonta anatina colonizam preferencialmente pools com substrato fino, com núcleos populacionais situados entre raízes submersas, próximo de margens escavadas. Por sua vez, a espécie Potomida littoralis apresenta densidades superiores em zonas de maior corrente (riffles) e substrato mais grosseiro (seixos e pedras). Foram ainda realizadas experiências laboratoriais para determinação da íctiofauna hospedeira das 3 espécies de unionídeos, do qual se realça a afinidade quase exclusiva destas náiades com a fauna piscícola autóctone (nomeadamente com ciprinídeos endémicos e salmonídeos). Face às ameaças detetadas, caso da poluição, sedimentação e especialmente da regularização que conduzirá a uma redução do habitat disponível e da íctiofauna nativa nos rios Sabor, Tua e Tâmega, é fundamental a conservação de habitats e ecossistemas prioritários e a requalificação ambiental de troços degradados de modo a preservar as espécies de invertebrados e vertebrados autóctones fortemente ameaçadas
- Biology and conservation of freshwater bivalves: past, present and future perspectivesPublication . Lopes-Lima, Manuel; Teixeira, Amílcar; Froufe, Elsa; Lopes, Anabela; Varandas, Simone; Sousa, RonaldoFreshwater bivalves have been highly threatened by human activities, and recently their global decline has been causing conservational and social concern. In this paper, we review the most important research events in freshwater bivalve biology calling attention to the main scientific achievements. A great bias exists in the research effort, with much more information available for bivalve species belonging to the Unionida in comparison to other groups. The same is true for the origin of these studies, since the publishing pattern does not always correspond to the hotspots of biodiversity but is concentrated in the northern hemisphere mainly in North America, Europe and Russia, with regions such as Africa and Southeast Asia being quite understudied. We also summarize information about past, present and future perspectives concerning the most important research topics that include taxonomy, systematics, anatomy, physiology, ecology and conservation of freshwater bivalves. Finally, we introduce the articles published in this Hydrobiologia special issue related with the International Meeting on Biology and Conservation of Freshwater Bivalves held in 2012 in Bragança, Portugal.
- 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.
- Combined per‐capita and abundance effects of an invasive species on native invertebrate diversity and a key ecosystem processPublication . Carvalho, Francisco; Pascoal, Cláudia; Cassio, Fernanda; Teixeira, Amílcar; Sousa, Ronaldo1. Invasive alien species (IAS) are leading to the homogenisation of taxonomic and functional biodiversity, with negative consequences for key ecosystem processes in fresh water. Invasive signal crayfish (Pacifastacus leniusculus) is expected to disrupt detritus-based food webs by affecting leaf breakdown and/or by decreasing invertebrate density and diversity through predation. The combination of per-capita and abundance effects of P. leniusculus in invaded ecosystems is still largely unknown. 2. A four-week field experiment was established in Rabaçal and Tuela Rivers (NE Portugal) to assess effects of P. leniusculus on invertebrate taxonomic and functional diversity and leaf litter breakdown following a gradient of invasion. We controlled the presence and absence of crayfish by placing the animals and leaf litter inside cages at six sites (three sites per river) according to the crayfish in situ abundance (absent, low, high). Cages were covered with coarse-or fine-mesh net to allow or prevent invertebrates from accessing the leaves. 3. Results showed that higher crayfish in situ abundance led to a decrease in abundance, richness and Shannon diversity of invertebrates and to changes in the communities’ structures. Higher crayfish abundance led also to a decrease in invertebrate functional redundancy and an increase in the percentage of invertebrate taxa with resistance forms. Leaf litter breakdown increased with crayfish presence and decreased at sites with higher crayfish abundance. 4. Overall, signal crayfish changed the community structure of invertebrates, with potential severe long-term effects on native communities and leaf litter breakdown. Given the widespread distribution of signal crayfish (and other crayfish species), their ecological impacts should be assessed carefully, especially in pristine freshwater ecosystems such as those described here.
- CONBI: Biodiversidade e conservação de bivalves – informação ecogeográfica, genética e fisiológica.Publication . Teixeira, Amílcar; Varandas, Simone; Sousa, Ronaldo; Froufe, Elsa; Lopes-Lima, ManuelUm dos grupos faunísticos mais ameaçados a nível mundial e em declínio global são os Unionidae (Mollusca), a maior de seis famílias de mexilhões de agua-doce. Para muitas espécies (independentemente do seu estatuto de conservação) no mundo inteiro, incluindo a Península Ibérica, são escassos, e em muitos casos inexistentes, os dados mais básicos sobre o seu ciclo de vida, dimensão e estrutura populacional, bem como a sua estrutura genética populacional. O presente projeto pretende preencher a lacuna de conhecimento sobre o estatuto da família Unionidae na Península Ibérica num contexto mais amplo da conservação da biodiversidade, sendo os principais objetivos: 1) compreender tanto a dinâmica atual das populações como a biogeografia histórica destes bivalves; 2) clarificar a sua diversidade taxonómica e afinidades filogenéticas; 3) compreender os mecanismos fundamentais da evolução do mtDNA dessas espécies; 4) descrever as suas principais características biológicas como a distribuição, estrutura populacional, época de reprodução, período larvar e peixes hospedeiros; 5) elucidar, do ponto de vista ecológico, os padrões de distribuição e os principais fatores bióticos e abióticos responsáveis pela sua distribuição. Sob uma perspetiva de gestão e conservação, pretende-se que os resultados obtidos possam ser usados para o desenvolvimento de estratégias futuras de conservação através da identificação de Unidades Evolutivas Significativas (ESUs) e de Unidades de Gestão (MUs). No presente trabalho são realçados aspetos da bioecologia de unionídeos no Nordeste Transmontano. E apresentada uma caracterização ecológica de populações das bacias do Sabor, Tua e Tâmega, assim como os ciclos de reprodução e peixes hospedeiros das espécies Anodonta anatina, Potomida littoralis e Unio delphinus.
- Conservation status of freshwater mussels in Europe: state of the art and future challengesPublication . Lopes-Lima, Manuel; Sousa, Ronaldo; Geist, Juergen; Aldridge, David C.; Araujo, Rafael; Bergengren, Jakob; Bespalaya, Yulia V.; Bódis, Erika; Burlakova, Lyubov E.; Van Damme, Dirk; Douda, Karel; Froufe, Elsa; Georgiev, Dilian; Gumpinger, Clemens; Karatayev, Alexander Y.; Kebapçi, Ümit; Killeen, Ian; Lajtner, Jasna; Larsen, Bjørn M.; Lauceri, Rosaria; Legakis, Anastasios; Lois, Sabela; Lundberg, Stefan; Moorkens, Evelyn A.; Motte, Gregory; Nagel, Karl Otto; Ondina, Paz; Outeiro, Adolfo; Paunovic, Momir; Prié, Vincent; Proschwitz, Ted von; Riccardi, Nicoletta; Rudzīte, Mudīte; Rudzītis, Māris; Scheder, Christian; Seddon, Mary; Şereflişan, Hülya; Simić, Vladica; Sokolova, Svetlana; Stoeckl, Katharina; Taskinen, Jouni; Teixeira, Amílcar; Thielen, Frankie; Trichkova, Teodora; Varandas, Simone; Vicentini, Heinrich; Zajac, Katarzyna; Zając, Tadeusz; Zogaris, StamatisFreshwater mussels of the Order Unionida provide important ecosystem functions and services, yet many of their populations are in decline. We comprehensively review the status of the 16 currently recognized species in Europe, collating for the first time their life-history traits, distribution, conservation status, habitat preferences, and main threats in order to suggest future management actions. In northern, central, and eastern Europe, a relatively homogeneous species composition is found in most basins. In southern Europe, despite the lower species richness, spatially restricted species make these basins a high conservation priority. Information on freshwater mussels in Europe is unevenly distributed with considerable differences in data quality and quantity among countries and species. To make conservation more effective in the future, we suggest greater international cooperation using standardized protocols and methods to monitor and manage European freshwater mussel diversity. Such an approach will not only help conserve this vulnerable group but also, through the protection of these important organisms, will offer wider benefits to freshwater ecosystems.
- Conservation status of the freshwater pearl mussel Margaritifera margaritifera in PortugalPublication . Sousa, Ronaldo; Amorim, Ângela; Froufe, Elsa; Varandas, Simone; Teixeira, Amílcar; Lopes-Lima, ManuelBased on new information, the current conservation status of the freshwater pearl mussel Margaritifera margaritifera (Linnaeus, 1758) in Portugal is revised. Between 2010 and 2013 surveys were conducted in eight different rivers to assess distribution, abundance, size-frequency and preferential habitat of this species. Rivers Neiva, Cávado and Terva presented very low abundances (in the Cávado no specimens were found) and showed acute signs of ageing, calling into question the future survival of these populations. Although abundances were low in Rivers Beça, Paiva and Mente, juveniles were present and populations may improve their conservation status in the future, if appropriate management measures are applied. Rivers Rabaçal and Tuela presented the highest abundances of adults and juveniles and these two rivers have the highest potential for the conservation of freshwater pearl mussels in Portugal. However, these two populations have suffered severe declines in several stretches due to the construction of dams in recent years. Given that the Portuguese pearl mussel populations are at the southern range of the species distribution, their conservation should be a priority. This current description of the conservation status of M. margaritifera in Portugal can be used as a reference, and guide future research and management initiatives to better conserve this species.