Author(s): Tamara Leite; Goncalo Duarte; Pedro Segurado; Maria Teresa Ferreira; Paulo Branco
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Keywords: No Keywords
Abstract: Humans greatly modify riverscapes by altering stretches, and watersheds, and accelerating climate changes. As a consequence of damming and channelization, longitudinal and lateral connectivity of rivers have been severely compromised, and most rivers are disconnected from their floodplains. The dramatic effects of dams on water, sediment transport and fish movements have made them a common subject of fluvial research. However, most research lacks the distinction between the independent effects of natural pre-existing barriers -waterfalls- and the artificial ones. Most studies have considered the dam as the principal or only barrier impairing longitudinal fish movements. However, the upstream water reservoir itself represents a strong ecological barrier because it creates completely different hydrological and limnological conditions. Furthermore, lateral fragmentation is also a significant threat to ecological functions in the river landscape, negatively affecting the development of side-channel habitats, floodplain evolution, riparian ecosystem processes, and biodiversity. Roads and railroads are even more abundant features in riverscapes than dams. Additionally, navigation in heavily developed waterways may impact diversity of fish assemblages, contributing to the effects of migration barriers, pollution, expansion of invasive species, and habitat destruction.
Year: 2024