EFFECT OF SLACKWATER AREAS ON THE ESTABLISHMENT OF PLANKTON COMMUNITIES (TESTATE AMOEBAE AND ROTIFERS) IN A LARGE RIVER IN THE SEMI-ARID REGION (NORTHEASTERN BRAZIL)
The increase in discharge of rivers over time and space poses challenges to the establishment of some biotas, because of higher turbulence, turbidity, hydraulic forces and limited food sources, which may directly affect the community structure. In this context, slackwater areas play an important role in the establishment of organisms, acting as refuges, reducing turbulence, turbidity and providing greater availability of food. This study investigated the changes in community structure of testate amoebae and rotifers in relation to the appearance and disappearance of slackwater areas formed by sandbars on a stretch of the Parnaíba River. The appearance of slackwaters promoted suitable environmental conditions for the establishment of rotifers. On the other hand, slackwaters acted as a buffer for testate amoebae, allowing them to colonize the plankton due to a lower suspension of sediment in these areas. We suggest that the intermittent presence of slackwaters in the Parnaíba River channel is an essential driver of abundance and succession patterns of species in the plankton, through the alternation of washing-out effects, taxon-specific potential of reproduction and biological interactions.