Morphological and ecological characterization of Batrachospermales (Rhodophyta) in the Jarama Basin, Iberian Peninsula

Five populations of freshwater red algae were investigated between February 2008 and September 2009 in four segments of the Jarama River Basin (Tajo Basin), Iberian Peninsula, between 40-41◦ N, 3-4◦ W, at 700 to 1200 m altitude. Three species were documented (Batrachospermum gelatinosum, Lemanea fluviatilis and Paralemanea catenata) and information was collected about includes their morphology and the physical and chemical characteristics of the water. All the taxa have been reported previously, but the present work includes the first detailed morphological description of red algae in the region and their ecological preferences. The waters in these study sites are cool to temperate (5-17 ◦C), acid to circumneutral (pH 6.3-7.5) and with a low ion concentration (specific conductivity 77-270 μS cm−1). Two groups were distinguished on the basis of nutrient concentration. The first group, which included B. gelatinosum and L. fluviatilis, is found in clean water with low nutrient concentration, while the second group, which included P. catenata, occurred in nutrient-rich water. Gametophytes of L. fluviatilis and P. catenata were present in all seasons, with the highest percentage cover in autumn and winter corresponding to high current velocity and low water temperature. However, gametophytes were longest, and spermatangial sori and carposporophytes were most abundant in spring when current velocity was low and water temperature was high. The distribution of Batrachosermales from the Jarama Basin showed a strong affinity with temperate regions of central Europe and floras of other continents.Se han estudiado cinco poblaciones de algas rojas de agua dulce durante el periodo de febrero 2008 a septiembre 2009, en cuatro segmentos de la cuenca del río Jarama (Cuenca del Tajo), Península Ibérica, entre latitudes (40-41◦ N, 3-4◦ O) y 700 a 1200 m de altitud. Se describe la morfología de 3 especies (Batrachospermum gelatinosum, Lemanea fluviatilis and Paralemanea catenata) junto con sus caracter'ısticas f'ısico-químicas del agua. Todos los taxones encontrados han sido ya citados, sin embargo el presente trabajo incluye la primera descripci'on morfol'ogica detallada de algas rojas en la región y sus preferencias ecológicas. Las zonas de estudio presentan aguas frías a templadas (5-17 ◦C), ácidas a neutrales (6.3-7.5) y relativamente baja concentración de iones (conductividad específica 77-270 μS cm−1). En función de la concentración de nutrientes se pueden distinguir 2 grupos. El primero, que incluye B. gelatinosum y L. fluviatilis, se encuentra en aguas con baja concentración de nutrientes, mientras que el otro grupo que contiene P. catenata aparece en aguas ricas en nutrientes. Los gametofitos de L. fluviatilis y P. catenata estuvieron presentes durante todas las estaciones del año, con la mayor cobertura porcentual en otoño e invierno y corresponden con la mayor velocidad de corriente y baja temperatura del agua. Sin embargo, el largo del gametofito, el número de soros espermatangiales y el número de carposporofitos fue mayor en primavera con la mayor temperatura del agua y la más baja velocidad de corriente. La distribución de las Batrachospermales en la cuenca del río Jarama, mostraron una fuerte afinidad con regiones templadas de Centroeuropa y otros continentes

No saturation in the accumulation of alien species worldwide

Although research on human-mediated exchanges of species has substantially intensified during the last centuries, we know surprisingly little about temporal dynamics of alien species accumulations across regions and taxa. Using a novel database of 45,813 first records of 16,926 established alien species, we show that the annual rate of first records worldwide has increased during the last 200 years, with 37% of all first records reported most recently (1970–2014). Inter-continental and inter-taxonomic variation can be largely attributed to the diaspora of European settlers in the nineteenth century and to the acceleration in trade in the twentieth century. For all taxonomic groups, the increase in numbers of alien species does not show any sign of saturation and most taxa even show increases in the rate of first records over time. This highlights that past efforts to mitigate invasions have not been effective enough to keep up with increasing globalization.© The Author(s) 201