Browsing by Author "Carvalho, Francisco"
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- 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.
- Die-offs of the endangered pearl mussel Margaritifera margaritifera during an extreme droughtPublication . Sousa, Ronaldo; Ferreira, André; Carvalho, Francisco; Lopes-Lima, Manuel; Varandas, Simone; Teixeira, AmílcarDroughts may be responsible for important ecological impacts in freswater ecosystems, including the death of rare species. This study assessed the mortality of the endadgered pearl mussel Margaritifera margarififera (Linnaeus, 1758) in the Mente, Rabaçal and Tuela rivers (north west of the Iberian Peninsula) during the extreme summer drought of 2017. Mortality ocuurred as a result of the low river flow, which led to mussel stranding near the banks and consumption (by predation of scavenging) by wild boar Sus scrofa (Linnaeus, 1758). Mortality differed across sites. The shell length of live mussels (measured before the drougt( and dead mussels significantly differed in the Rabaçal River, but not in the Mente and Tuela rivers. Extreme droughts are predicted to increase in number and intensity i the future, and possible impacts on rare species such as M. margaritifera populations in Iberia (and elsewhere) may now be at increased risk, and measures should be implemented in order to mitigate the impacts of future extreme droughts.
- Interspecific differences in the physiological condition of native freshwater mussels in response to the invasive Asian clam Corbicula flumineaPublication . Modesto, Vanessa; Ilarri, Martina; Castro, Paulo S.; Carvalho, Francisco; Cavalheri, Thais; Lopes-Lima, Manuel; Teixeira, Amílcar; Ozório, Rodrigo O.A.; Antunes, Carlos; Sousa, RonaldoThe Asian clam Corbicula fluminea has been widely introduced into aquatic ecosystems and may impact the physiological condition and survival of native freshwater mussels. However, very few studies have evaluated this issue quantitatively. To fill this gap, manipulative field experiments were performed to assess two possible mechanisms of impact on native mussels: (i) interspecific interactions, and (ii) C. fluminea die-offs. We assessed these effects by measuring the physiological condition through the analysis of glycogen content in the foot tissue of the native freshwater mussel species Anodonta anatina, Potomida littoralis, and Unio delphinus. Although with interspecific differences, our results suggest that C. fluminea can impact the physiological condition of native freshwater mussels. Anodonta anatina showed positive significant variations on glycogen content when subjected to high densities of live C. fluminea in contrast to the other native species studied, P. littoralis and U. delphinus, where no significances were observed. On the other hand, these native species do not seem be significantly impacted by the decomposition of C. fluminea resulting from a die-off. Overall, and contrary to our expectations, both experiments showed a positive (or no) effect of C. fluminea on the physiological condition of the three freshwater mussel species.
- 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.
- Multiple introductions and first record of Phoxinus phoxinus in the Douro Basin revealed by molecular dataPublication . Garcia-Raventós, Aina; Martins, Filipa; Magalhães, Maria Filomena; Ramião, José; Ferreira, Mário; Carona, Sara; Carvalho, Francisco; Sousa, Ronaldo; Froufe, Elsa; Teixeira, Amílcar; Varandas, Simone; Lopes-Lima, Manuel; Beja, Pedro; Filipe, Ana FilipaBiological invasions are a major threat to global biodiversity. Freshwater ecosystems are particularly vulnerable to anthropogenic introductions. This is the case of the minnows (Phoxinus genus), which have been used as a live bait since the 1900s. Until recently, Phoxinus phoxinus was thought to be distributed across most of the European watercourses, including the Iberian Peninsula (Ebro Basin and Cantabrian region). In 2007, these Iberian populations were identified as Phoxinus bigerri, including the traslocated populations in the Douro Basin near Burgos (Spain). Currently, little is known about the distribution of Phoxinus bigerri in the Douro Basin. During early summer 2017, we sampled 75 stream reaches using electrofishing across the Douro Basin (Portugal and Spain). We identified 267 individuals as the Pyrenean minnow P. bigerri, and we cliped and stored fin tissues from 153 individuals in 96% ethanol for DNA reference collection. Among those, 26 were barcoded for cytochrome oxidase I (COI) and cytochrome b (Cytb) genes to confirm the taxonomic identification at the species level. Results confirmed for the first time the presence of the common minnow P. phoxinus in the Douro basin, being five individuals collected in the western Douro (Portugal near Porto) closely related to populations from Adour Basin in France. The remaining 21 individuals from eastern Douro (Spain near Brugos) were identified as P. bigerri, as expected. Our study is the first record of P. phoxinus in the Douro Basin, which can be easly missidentified when using only morphologically identifications. The study highlights the value of using molecular approaches for detecting new introductions and tracking spread histories, which can be relevant for designing proper management plans. The P. phoxinus introduction in western Douro (Portugal) seem to be related with human activities (sport fisheries by Portuguese immigrants living in France) rather than geographical proximity.
- Multiple introductions and first record of Phoxinus phoxinus in the Douro basin revealed by molecular dataPublication . Garcia-Raventós, Aina; Martins, Filipa; Magalhães, Maria Filomena; Ramião, José; Ferreira, Mário; Carona, Sara; Carvalho, Francisco; Sousa, Ronaldo; Froufe, Elsa; Teixeira, Amílcar; Varandas, Simone; Lopes-Lima, Manuel; Beja, Pedro; Filipe, Ana FilipaBiological invasions are a major threat to global biodiversity. Freshwater ecosystems are particularly vulnerable to anthropogenic introductions. This is the case of the minnows (Phoxinus genus), which have been used as a live bait since the 1900s. Until recently, Phoxinus phoxinus was thought to be distributed across most of the European watercourses, including the Iberian Peninsula (Ebro Basin and Cantabrian region). In 2007, these Iberian populations were identified as Phoxinus bigerri, including the traslocated populations in the Douro Basin near Burgos (Spain). Currently, little is known about the distribution of Phoxinus bigerri in the Douro Basin. During early summer 2017, we sampled 75 stream reaches using electrofishing across the Douro Basin (Portugal and Spain). We identified 267 individuals as the Pyrenean minnow P. bigerri, and we cliped and stored fin tissues from 153 individuals in 96% ethanol for DNA reference collection. Among those, 26 were barcoded for cytochrome oxidase I (COI) and cytochrome b (Cytb) genes to confirm the taxonomic identification at the species level. Results confirmed for the first time the presence of the common minnow P. phoxinus in the Douro basin, being five individuals collected in the western Douro (Portugal near Porto) closely related to populations from Adour Basin in France. The remaining 21 individuals from eastern Douro (Spain near Brugos) were identified as P. bigerri, as expected. Our study is the first record of P. phoxinus in the Douro Basin, which can be easly missidentified when using only morphologically identifications. The study highlights the value of using molecular approaches for detecting new introductions and tracking spread histories, which can be relevant for designing proper management plans. The P. phoxinus introduction in western Douro (Portugal) seem to be related with human activities (sport fisheries by Portuguese immigrants living in France) rather than geographical proximity.
- Multiple introductions and first record of Phoxinus phoxinus in the Douro basin revealed by molecular dataPublication . Garcia-Raventós, Aina; Martins, Filipa; Magalhães, Maria Filomena; Ramião, José; Ferreira, Mário; Carona, Sara; Carvalho, Francisco; Sousa, Ronaldo; Froufe, Elsa; Teixeira, Amílcar; Varandas, Simone; Lopes-Lima, Manuel; Beja, Pedro; Filipe, Ana FilipaBiological invasions are a major threat to global biodiversity. Freshwater ecosystems are particularly vulnerable to anthropogenic introductions, including in the Iberian Peninsula where the number of introduced species has been increasing during the last decades. This is the case of the minnows (Phoxinus genus), which have been used as a live bait since the 1900s. Until recently, Phoxinus phoxinus was thought to be distributed across most of the European watercourses, including the Iberian Peninsula in the Ebro Basin and some streams of the Cantabrian region. In 2007, these Iberian populations were identified as Phoxinus bigerri, including the traslocated populations in the Douro Basin near Burgos (Spain). Currently, little is known about the distribution of Phoxinus bigerri in the Douro Basin. During early summer 2017, we sampled 75 stream reaches using electrofishing across the Douro Basin (Portugal and Spain). We identified 267 individuals as the Pyrenean minnow P. bigerri, and we cliped and stored fin tissues from 153 individuals in 96% etanol for DNA reference collection. Among those, 26 were barcoded for cytochrome oxidase I (COI) and cytochrome b (Cytb) genes to confirm the taxonomic identification at the species level. Results confirmed, for the first time, the presence of the common minnow P. phoxinus in the Douro basin, being five individuals collected in the western Douro (Portugal near Porto) closely related to populations from Adour Basin in France. The remaining 21 individuals from eastern Douro (Spain near Brugos) were identified as P. bigerri, as expected. Our study is the first record of P. phoxinus in the Douro Basin, which can be easly missidentified when using only morphologically identifications. The study highlights the value of using molecular approaches for detecting new introductions and tracking spread histories, which can be relevant for designing proper management plans dealing with erradication, control or containemnt of invasive species. Importantly, the P. phoxinus introduction in western Douro river (Potugal) seem to be related with human activities (sport fisheries by Portuguese immigrants living in France) rather than geographical proximity.
- A roadmap for the conservation of freshwater mussels in EuropePublication . Sousa, Ronaldo; Zając, Tadeusz; Halabowski, Dariusz; Aksenova, Olga V.; Bespalaya, Yulia V.; Carvalho, Francisco; Castro, Paulo S.; Douda, Karel; Silva, Janine P.; Ferreira-Rodríguez, Noé; Geist, Juergen; Gumpinger, Clemens; Labecka, Anna M.; Lajtner, Jasna; Lewin, Iga; Lopes-Lima, Manuel; Meira, Alexandra; Nakamura, Keiko; Nogueira, Joana Garrido; Ondina, Paz; Ożgo, Małgorzata; Reis, Joaquim; Riccardi, Nicoletta; Shumka, Spase; Son, Mikhail O.; Teixeira, Amílcar; Thielen, Frankie; Urbańska, Maria; Varandas, Simone; Wengström, Niklas; Zajac, Katarzyna; Zieritz, Alexandra; Aldridge, David C.Europe has a long history of human pressure on freshwater ecosystems. As pressure continues to grow and new threats emerge, there is an urgent need for conservation of freshwater biodiversity and its ecosystem services. However, whilst some taxonomic groups, mainly vertebrates, have received a disproportionate amount of attention and funds, other groups remain largely off the public and scientific radar. Freshwater mussels (Bivalvia, Unionida) are an alarming example of this conservation bias and here we point out six conceptual areas that need immediate and long-term attention: knowledge, threats, socioeconomics, conservation, governance and education. The proposed roadmap aims to advance research, policy and education by identifying the most pressing priorities for the short- and long-term conservation of freshwater mussels across Europe.
- Small hydropower plants as a threat to the endangered pearl mussel Margaritifera margaritiferaPublication . Sousa, Ronaldo; Ferreira, André; Carvalho, Francisco; Lopes-Lima, Manuel; Varandas, Simone; Teixeira, Amílcar; Gallardo, BelindaFreshwatermussels are undergoing rapid global declines due to habitat loss and fragmentation, among other factors, but little is known about the effects of small hydropower plants. Here we assessed the impact of small hydropower plants on the abundance and size structure of the imperilled pearl mussel Margaritifera margaritifera. For this, we sampled 66 sites in three Portuguese rivers (Mente, Rabaçal and Tuela) located upstreamand downstream of dams andwithin the reservoirs. Pearl musselswere significantly more abundant upstreamthan downstream of dams (97.4% more) or within reservoirs (98.5% more). In addition, juveniles were mostly found upstream of dams. The most significant environmental alterations that explained the observed patterns were related to changes in sediment characteristics (accumulation of fine sediments and organic matter in reservoirs) andwater chemistry, most notably suspended solids (highest values in reservoirs) and dissolved oxygen (lowest values in reservoirs). Overall, results show that small hydropower plants can deeply affect pearl mussel populations: specimens almost disappeared from the areas within the reservoirs and sites located downstream only retained adults without signs of recent recruitment. Future management measures devoted to the conservation of pearlmussels should take into account the results reported here to avoid the construction of newdamsin pearl mussel rivers; improve management of the river flow in downstream areas; and consider the decommissioning of dams in pearlmussel riverswith a particular attention devoted to the re-naturalization of river sections under the influence of the reservoir and downstream areas.
- A tale of shells and claws: The signal crayfish as a threat to the pearl mussel Margaritifera margaritifera in EuropePublication . Sousa, Ronaldo; Nogueira, Joana Garrido; Ferreira, André; Carvalho, Francisco; Lopes-Lima, Manuel; Varandas, Simone; Teixeira, AmílcarThe freshwater pearl mussel Margaritifera margaritifera is a highly threatened species in Europe. Several mechanisms may be responsible for the decline in distribution and abundance of European pearl mussel populations, but almost no quantitative data exists about the possible negative impacts of invasive alien species (IAS). In this study, we clearly demonstrate that the invasive signal crayfish Pacifastacus leniusculus predates pearl mussels, using a laboratorial experiment followed by in situ validation in four rivers in the North of Portugal (Mente, Rabaçal, Tuela and Baceiro Rivers; Douro Basin). In the laboratory, the crayfish had a clear preference for small-sized pearl mussels but no differences in predation were found in mesocosms with and without sediment. In addition, we clearly demonstrated that the signal crayfish predates pearl mussels in natural conditions and detected a significant density dependent effect (i.e., sites with more crayfish presented higher number of pearl mussel shells with marks of predation). Given the recent introduction of the signal crayfish and the potential negative impacts on pearl mussel populations we also investigated its autoecology (distribution, abundance, size structure and sex-ratio) in the four studied rivers. Significant differences in average abundance and size of the crayfish were detected between sites and the sex-ratio was highly skewed to females. In view of the widespread distribution of signal crayfish (and other invasive crayfish species) in Europe, future management actions devoted to the conservation of pearl mussels should take in consideration the possible negative effects of these predators, especially on juveniles.