Como o espaço e múltiplas escalas temporais estruturam a diversidade planctônica?

Abstract

In this study, we investigate the processes that influence the diversity of planktonic communities in space and time. We split the research into two approach. In the first, we evaluated the effect of different temporal scales on the structure of planktonic communities (ciliates, zooplankton and phytoplankton). We used as model two lakes located at the Upper Paraná River floodplain, and a data time series of 15 years. The results suggested that community variation in both fine (months) and broad (years) temporal scales had a high importance for plankton diversity in floodplain lakes. However, the processes that influenced the composition changes varied among communities. Phytoplankton and zooplankton seem to respond to deterministic processes (resource availability and grazing), while variation of ciliates seems to be influenced mainly by stochastic processes. In the second approach, we evaluated the effect of the construction of a reservoir on the spatial and temporal patterns of plankton (zooplankton and phytoplankton). In this study, we were also interested in analyzing how the influence of dispersion and the environment on these communities changes over time. The results suggested that the construction of a reservoir adversely affects the regional diversity of the plankton by reducing the variation in the space and time of the communities. Also, that the spatial variation of the communities was controlled primarily by environmental processes before the reservoir construction, and by spatial processes associated with high dispersion after the damming because the increased connectivity.