Percorrer por autor "Meira, Alexandra"
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- Invasive crayfishes as a threat to freshwater bivalves: Interspecific differences and conservation implicationsPublication . Meira, Alexandra; Lopes-Lima, Manuel; Varandas, Simone; Teixeira, Amílcar; Arenas-Arenas, Francisco José; Sousa, RonaldoFreshwater bivalves have suffered major global declines, being the introduction of invasive alien species (IAS) an important, but not well studied, mechanism of threat. This study assessed the predator-prey relationship between two non-native crayfish species (Procambarus clarkii and Pacifastacus leniusculus) and three native (Anodonta anatina, Potomida littoralis and Unio delphinus) and one non-native (Corbicula fluminea) freshwater bivalve species through experiments in laboratory and validation under natural conditions (Sabor River basin, Portugal). All native bivalve species were preyed both in laboratory and in the field; however, both crayfish species were unable to prey C. fluminea. Predation was dependent on crayfish and bivalve species but was not affected neither by crayfish nor bivalve sizes. In the laboratory, the most preyed species by both crayfishes was A. anatina. On average, this species was preyed at least 12% more than other species, when crayfishes had a choice. Similar results were found in the field. We also found signs of competition between both crayfishes, being P. clarkii more dominant and aggressive as this species, on average, manipulated the bivalves 63.6% more times and 24:33 min longer than P. leniusculus, and initiated 55.8% more agnostic bouts. Our results support the idea that P. clarkii and P. leniusculus can affect native freshwater bivalves, but clear interspecific differences were detected. Both crayfishes may have direct and indirect impacts on bivalve populations by increasing mortality or by reducing their fitness. In addition, since both crayfishes do not prey C. fluminea, they offer this IAS another advantage over native bivalves. Given the widespread distribution of both P. clarkii and P. leniusculus and the threatened status of many freshwater bivalves, the dynamics and impacts of this relationship should be taken in account in the implementation of management measures devoted to the conservation of native freshwater bivalves.
- Invasive crayfishhes as a threat to native freshwater bivalvesPublication . Sousa, Ronaldo; Meira, Alexandra; Arenas-Arenas, Francisco José; Lopes-Lima, Manuel; Varandas, Simone; Teixeira, AmílcarProcambarus clarkii and Pacifastacus leniusculus are problematic invasive species and may affect freshwater bivalves. In this study we verified ifthese crayfish species can predate native (Anodonta anatína, Potomida littoralis and Unio delphinus) and non-native (Corbicula fluminea) bivalves through experiments in laboratory and validation in the field (Sabor basin, North of Portugal). In the laboratoiy, crayfish feeding preferences and competition between the two crayfish species were also assessed. In the field, abundances and lengths of the specimens of each bivalve species were recorded, crayfish predation marks on bivalves were quantified and crayfish distribution, abundance and sexwere determined. AU native bivalve species were preyed both in laboratoiy and in the field; however, P. clarkii and P. leniusculus were unable to prey the non-native C. fluminea. Bivalve predation was not afifected neither by the length or sex ofthe crayfish. The most preyed native species by both crayfishes was A. anatina. We also found competition for bivalves as a prey between the crayfishes, being P. clarkii dominant and displaying a more aggressive behaviour than P. leniusculus. Results of this study support the idea that P. clarkü and P. leniusculus can affect native bivalves by decreasing the number of effectives by increasing mortality and by reducing their fítness, which may have indirect impacts on freshwater ecosystems. On the other hand, and since crayfishes did not prey C. fluminea offers this invasive bivalve another advantage over native species. FinaUy, we also assessed the predation ofP. leniusculus on Margaritifera margaritifera in the Tua basin (North of Portugal) and our results confirm this invasivc crayfish as a threat to pearl mussels. Therefore, future management actions devoted to the conservation of freshwater bivalves should have in account the possible effects of invasive crayfishes on these organisms.
- 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.