Conservation benefits of riparian buffers in urban areas: the case of the Rio Corgo (north Portugal)
Coelho, Diana; Hughes, Samantha Jane; Varandas, Simone; Cortes, Rui Manuel Vítor
published: Oct 1, 2014
ArtNo. ESP141018501006, Price: 29.00 €
The widespread urbanization of river catchments has resulted in the degradation of many fluvial ecosystems. We examined the hypothesis that riparian vegetation corridors form effective buffers, mitigating the effects of anthropogenic disturbances in urban river systems. We aimed to identify the principal factors affecting ecological status and biological diversity in the River Corgo (northern Portugal) in order to develop a programme of rehabilitation measures. Data were collected from urban reaches and downstream rural reaches of the River Corgo. We assessed the habitat preferences of two native cyprinid fish species Pseudochondrostoma duriense and Luciobarbus bocagei and also sampled the benthic macroinvertebrate fauna, physicochemical characteristics and hydromorphological support elements following Water Framework Directive compliant protocols. Fish habitat preference curves indicated that the specific habitat preferences of the target native cyprinid fish species were influenced by riparian zone vegetation quality, in addition to micro-habitat characteristics (substrate, current velocity and shelter). Sampling sites located in the urban centre were found to have higher ecological status than sites located in downstream rural and agricultural areas. This may reflect the increased habitat quality and buffering capacity of riparian vegetation, which was better preserved at urban sites. Despite this, non-native fish species were more abundant within urban sites compared to downstream rural sites. The results indicate the significant cumulative effect of anthropogenic influences on downstream sites, such as diffuse pollution from agriculture and loss of riparian cover. Based on the results of this study we recommend that rehabilitation measures should be directed to: a) improve the connectivity of the flowing channel in urban reaches; and b) restore the riparian corridor in the other reaches affected by nutrient input and the spread of invasive fish species.