Human and natural drivers of changing macrophyte community dynamics over 12 years in a Neotropical riverine floodplain system

摘要: The Rio Parana is the world's tenth largest river (discharge in upper river, studied here, during major flood events exceeds 12 700 m3 s-1). Together with its associated floodplain water bodies, this Neotropical system supports a freshwater biodiversity of worldwide conservation significance, but one increasingly affected by human pressures, particularly effects impoundment. Multivariate analysis data from repeated (2000–2002 and 2011) macrophyte–environment surveys set stations within 230 km stretch functioning riverine floodplain, downstream most recently completed dam on Upper Parana, Porto Primavera Dam, together published (from 1999 2005–2007), was used to test hypothesis that influences might outweigh importance natural factors driving aquatic vegetation dynamics (macrophyte community composition, alpha-diversity, abundance) period 1999–2011. The macrophyte communities present showed differences species composition abundance could be strongly related scale duration immediately preceding annual pulse, as well local variations physico-chemical conditions. For rare endemic species, which are good marker status system, there reasonable degree stability between 2000–2002 2011 survey periods, eight 16 such being both surveys, three only, an additional five found only 2011. The conclusion changes can referred direct impacts (river regulation), indirect or (floods, alien invasion Hydrilla verticillata, environmental factors). Overall evidence floods El Nino - Southern Oscillation (ENSO) climatic had much greater impact than other drivers, whether anthropogenic. Copyright © 2013 John Wiley & Sons, Ltd.