Nova Clarice C, Lopes Vanessa G, Souza Leonardo Coimbra E, Kozlowsky-Suzuki Betina, Pereira Talita A A, Branco Christina W C
Departamento de Ecologia, Instituto de Biologia, Universidade Federal do Rio de Janeiro/ UFRJ, Rio de Janeiro, RJ, Brasil.
Departamento de Ecologia e Evolução, Instituto de Ciências Biológicas, Universidade Federal de Goiás /UFG, Goiânia, GO, Brasil.
An Acad Bras Cienc. 2014 Sep;86(3):1359-72. doi: 10.1590/0001-3765201420130323. Epub 2014 Aug 12.
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.
轮虫常被用作水生环境物理和化学特征突然变化的指标。在与主要洪泛平原相连的小湖泊的洪水脉冲事件期间，这些特征变化很大。然而，很少有研究调查洪水脉冲对轮虫物种组成、丰度、丰富度和多样性的影响，尤其是在亚马逊地区的湖泊。我们分析了来自亚马孙中部一个与内格罗河永久相连的“igarapé”小黑水湖的样本。样本在两年内每年采集两次，涵盖洪水脉冲的涨水期和退水期。干旱事件后轮虫丰度显著增加，电导率和浊度与这种变化存在内在联系。物种组成也从涨水期到退水期发生了变化。一些分类群，如Brachionus zahniseri reductus和Lecane remanei仅限于退水期，而Brachionus zahniseri、Brachionus gillardi和Lecane proiecta仅在涨水期出现。从一个时期到另一个时期观察到轮虫科组成的转变，显示了洪水脉冲更新水体的影响。这些结果表明，洪水脉冲作为一种驱动力和胁迫条件，极大地改变了轮虫群落动态，要么改变物种组成，要么降低丰度。
