摘要
Aquatic systems in semi-arid Brazil include natural shallow lakes, artificial reservoirs and intermittent streams and rivers. These systems are distinctive features in the semi-arid landscape and comprise a range of associated systems functioning as an ever-changing mosaic of dry/wet patches. Lakes and reservoirs in semi-arid Brazil are subject to important periods of water shortages, whereas rivers and streams are characterized as highly variable and driven by the extremes of water flow and its absence. Within this view a catchment-scale approach must be used to create a holistic model to conceptualize and comprehend these aquatic systems, since the aquatic environment types in the semi-arid region of Brazil incorporate broader aspects within the catchment scale such as geomorphology, vegetation, climate and land use. This paper summarizes some of the information on the aquatic systems of the Brazilian semi-arid region and shows the importance of limnological studies in this region. It also attempts to establish perspectives for future research considering the catchment as a scale for surveying biological processes and limnological characteristics of the various aquatic systems. It is presented information on their overall structure and functioning, as well as characteristics of some biological communities, such as phytoplankton, periphyton, aquatic macrophytes, benthic invertebrates and fish. The importance of the understanding of eutrophication in reservoirs and the role of the dry phase in streams is emphasized, and information on possible actions of planning and management to improve water quality of reservoirs are presented. Os ecossistemas no semi芍rido brasileiro englobam lagos rasos naturais, reservat車rios artificiais e rios e riachos intermitentes. Estes sistemas s o particularidades na paisagem do semi芍rida e compreendem uma grande variedade de sistemas associados, funcionando como um mosaico em constante mudan a entre 谷pocas de seca e chuva. Lagos e reservat車rios no semi芍rido brasileiro est o sujeitos a importantes per赤odos de escassez de 芍gua, enquanto que os rios e riachos s o caracterizados como altamente vari芍veis e impulsionados pelos extremos de fluxo de 芍gua e sua aus那ncia. Dentro desta perspectiva uma abordagem em escala de bacia hidrogr芍fica deve ser usada para se criar um modelo hol赤stico para conceituar esses sistemas aqu芍ticos, uma vez que os tipos de ambientes aqu芍ticos na regi o semi芍rida do Brasil incorporam aspectos mais amplos dentro da escala de bacia hidrogr芍fica como geomorfologia, clima, vegeta o e uso da terra. Este art