The effect of seasonality on the structure of rotifers in a black-water shallow lake in Central Amazonia

Abstract

Rotifers have often been used as indicators of sudden changes in physical and chemical features of the aquatic environment. Such features vary greatly during flood pulse events in small lakes connected to major floodplains. However, few are the studies that investigate the consequences of the flood pulse in rotifer species composition, abundance, richness and diversity, especially in Amazonian lakes. We analyzed samples from a small blackwater lake of an "igarapé" connected permanently to the Negro river, in Central Amazonia. Samples were taken twice a year for two years, comprising flooding and receding periods of the flood pulse. Rotifer abundance increased significantly after draught events, and electrical conductivity and turbidity were intrinsically related to such variation. Species composition also changed from flooding to receding periods. Some taxa, such as Brachionus zahniseri reductus and Lecane remanei were restricted to receding periods, while Brachionus zahniseri, Brachionus gillardi and Lecane proiecta were only present during flooding. A shift in the composition of rotifer families was observed from one period to another, showing the effect of renewing waters of the flood pulse. These results suggest that the flood pulse acts as a driving force and stressing condition, considerably altering rotifer community dynamics, either changing species composition or decreasing abundance.

The effects of mining tailings and flood pulse on zooplankton in an Amazonian floodplain environment (Batata Lake, Pará, Brazil)

“…All interperiod comparisons were statistically different, with the exception of flood and drawdown (Figure 4). Flood and drawdown may differs in relation to hydrology (Junk, 1997), nutrient dynamics (Reckendorfer et al, 2013) and even in biological communities (Nova et al, 2014) but in this study we found that intermediate level in itself played a major role in zooplankton densities. Differences in densities of the zooplanktonic groups (Figures 5-7) also showed some difference among periods, in accordance to the general density pattern.…”

“…Several authors have studied different aspects of zooplankton in Amazonian floodplain aquatic environments (Brandorff & de Andrade, 1978;Hardy et al, 1984;Bozelli & Esteves, 1995;Pinilla et al, 2007;Nova et al, 2014;Torres-Bejarano et al, 2014) but much remains to be discovered. In addition, zooplankton responds rapidly to disturbances and human interference.…”

Seasonal fluctuations of Rotifera in a tropical lake in Amazonia (Acre River floodplain, Brazil)

“…Silva et al (2012), studying the small Jesumira River located within the Serra National Park of Divisor, also found these families to be the most representative. High numbers of diversity for these families have also been cited in other environments of the Amazon region: Trichocerca by Brandorff & Koste (1982), Nova et al (2014), and Brachionus by Koste & Hardy Rodrigues (1984). Brachionidae was also the richest species according to De Paggi et al 2012, who investigated a shallow lake in a floodplain in Argentina.…”

Limnology and Rotifer Fauna of Khushalsar lake,Kashmir

“…Synchaeta sp. has been reported to be cold water genus by number of workers.It was also reported it to be present in oligotrophic and mesotrophic waters 20 . In the present study it showed its abundance in colder months and was present only at site K2 in Khushalsar lake.…”