How the fluctuations of water levels affect populations of invasive bivalve Corbicula fluminea (Müller, 1774) in a Neotropical reservoir?

Corbicula fluminea is an invasive bivalve responsible for several environmental and financial problems around the globe. Despite the invasive potential of this species, it suffers certain restrictions in lentic environments due to natural phenomena that significantly affect its population structure (e.g. water column fluctuation and sunlight exposure). The present study addresses how temporal decline of the water level in a Neotropical reservoir and exposure to sunlight affect the population structure of C. fluminea. Samplings were carried out twice in the reservoir of Furnas Hydroelectric Power Station (HPS) (Minas Gerais, Brazil), in 2011 and 2012. Population density, spatial distribution and mean shell length of C. fluminea were estimated for each year after sampling in 51 quadrats (0.0625m2) placed on three transects at different distances along the reservoir margins (0, 10 and 20 m from a fixed-point). We observed a predominance of C. fluminea in both years, with a simultaneous gradual decrease in density and richness of native species in the sampling area. Significant differences in density of C. fluminea were registered at different distances from the margin, and are related to the temporal variability of physical conditions of the sediment and water in these environments. We also registered a trend toward an increase in the density and aggregation of C. fluminea as we moved away from the margin, due to the greater stability of these areas (>10 m). The mean shell length of C. fluminea showed significant difference between the distinct distances from the margin and during the years, as well as the interaction of these factors (Distances vs.Years). These results were associated with the reproductive and invasive capacity of this species. This study reveals that these temporal events (especially water column fluctuation) may cause alterations in density, spatial distribution and mean shell length of C. fluminea and the composition of the native malacofauna in Neotropical lentic environments

How the fluctuations of water levels affect populations of invasive bivalve Corbicula fluminea (Müller, 1774) in a Neotropical reservoir?

Corbicula fluminea is an invasive bivalve responsible for several environmental and financial problems around the globe. Despite the invasive potential of this species, it suffers certain restrictions in lentic environments due to natural phenomena that significantly affect its population structure (e.g. water column fluctuation and sunlight exposure). The present study addresses how temporal decline of the water level in a Neotropical reservoir and exposure to sunlight affect the population structure of C. fluminea. Samplings were carried out twice in the reservoir of Furnas Hydroelectric Power Station (HPS) (Minas Gerais, Brazil), in 2011 and 2012. Population density, spatial distribution and mean shell length of C. fluminea were estimated for each year after sampling in 51 quadrats (0.0625m2) placed on three transects at different distances along the reservoir margins (0, 10 and 20 m from a fixed-point). We observed a predominance of C. fluminea in both years, with a simultaneous gradual decrease in density and richness of native species in the sampling area. Significant differences in density of C. fluminea were registered at different distances from the margin, and are related to the temporal variability of physical conditions of the sediment and water in these environments. We also registered a trend toward an increase in the density and aggregation of C. fluminea as we moved away from the margin, due to the greater stability of these areas (>10 m). The mean shell length of C. fluminea showed significant difference between the distinct distances from the margin and during the years, as well as the interaction of these factors (Distances vs.Years). These results were associated with the reproductive and invasive capacity of this species. This study reveals that these temporal events (especially water column fluctuation) may cause alterations in density, spatial distribution and mean shell length of C. fluminea and the composition of the native malacofauna in Neotropical lentic environments

Non-native mollusks throughout South America: emergent patterns in an understudied continent

Non-native species have been introduced at escalating rates during the last decades, mainly due to the dispersion generated by the increasing trade and transport worldwide. Mollusks, the second largest metazoan phylum in terms of species richness, are no exception to this pattern, but, to date, a comprehensive synthesis of non-native mollusk species (NNMS) in South America was not available. For this purpose, an e-discussion group was formed with malacologists and taxonomists from South America, where we exchanged and analyzed bibliography, databases and information about NNMS, providing expert opinion to this assessment. The first list of non-native mollusk species for South America, considering terrestrial, freshwater and marine environments, includes 86 NNMS distributed in 152 ecoregions (terrestrial, freshwater and marine) of the 189 recognized for the South American continent. Information on their native region, vectors, first record for South America and distribution, are also provided. In the analysis of the distribution of the NNMS and the entry points of each species (e.g., ports, cargo and passenger airports, cities) and status of conservation of the ecoregions, four hot spots were recognized: Subtropical-Atlantic, Northern Andes, Central Andes and Southern Andes. This work, thus, sets the baseline on NNMS for South America, a key piece of information regarding the development of policies targeting the management of biological invasions and their socio-ecological impacts.Fil: Darrigran, Gustavo Alberto. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. División de Zoología Invertebrados; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata; ArgentinaFil: Agudo Padrón, Ignacio. Projeto ''Avulsos Malacológicos''; BrasilFil: Baez, Pedro. Sociedad Malacológica Chile; Chile. Universidad Andrés Bello; ChileFil: Belz, Carlos Eduardo. Universidade Federal do Paraná; BrasilFil: Cardoso, Franz. Universidad Nacional Mayor de San Marcos; PerúFil: Carranza, Alvar. Universidad de la República; Uruguay. Ministerio de Educación y Cultura. Museo Nacional de Historia Natural; UruguayFil: Collado, Gonzalo. Sociedad Malacológica Chile; Chile. Universidad del Bıo Bio; ChileFil: Correoso, Modesto. Universidad de Las Fuerzas Armadas; EcuadorFil: Cuezzo, Maria Gabriela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto de Biodiversidad Neotropical. Universidad Nacional de Tucumán. Facultad de Ciencias Naturales e Instituto Miguel Lillo. Instituto de Biodiversidad Neotropical. Instituto de Biodiversidad Neotropical; ArgentinaFil: Fabres, Alejandra. Sociedad Malacológica Chile; Chile. Universidad de Chile; ChileFil: Gutiérrez Gregoric, Diego E.. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. División de Zoología Invertebrados; Argentina. Universidad del Bio Bio; Chile. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata; ArgentinaFil: Letelier, Sergio. Sociedad Malacológica Chile; ChileFil: Ludwig, Sandra. Universidade Federal de Minas Gerais; BrasilFil: Mansur, Maria Cristina. Universidade Federal do Rio Grande do Sul; BrasilFil: Pastorino, Roberto Santiago Guido. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales "Bernardino Rivadavia"; ArgentinaFil: Penchaszadeh, Pablo Enrique. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales "Bernardino Rivadavia"; ArgentinaFil: Peralta, Carolina. Universidad Simon Bolivar; VenezuelaFil: Rebolledo, Andrea. Sociedad Malacológica Chile; ChileFil: Rumi Macchi Z., Alejandra. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. División de Zoología Invertebrados; Argentina. Universidade Federal do Rio Grande do Sul; Brasil. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata; ArgentinaFil: Santos, Sonia. Universidade Do Estado de Rio Do Janeiro. Instituto de Biologia "roberto Alcantara Gomes".; BrasilFil: Thiengo, Silvana Aparecida Rogel. Instituto Oswaldo Cruz; BrasilFil: Vidigal, Teofania Heloisa Dutra Amorim. Universidade Federal de Minas Gerais; BrasilFil: Damborenea, Maria Cristina. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. División de Zoología Invertebrados; Argentina. Smach; Chile. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata; Argentin