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Flor-Arnau N.,University of Barcelona | Real M.,United Research Services Espana | Gonzalez G.,United Research Services Espana | Sanchez J.C.,University of Barcelona | And 3 more authors.
Limnetica | Year: 2015

The Water Framework Directive (WFD) implementation requires the use of biological quality elements to assess ecological status in water bodies, including aquatic flora. Previous macrophyte indices have been developed for rivers in several Mediterranean regions of the Iberian peninsula. Due to the lack of a suitable tool that would consider macrophyte and physicochemical characteristics of all Spanish Mediterranean fluvial types, the Fluvial Macrophyte Index (IMF) was designed in compliance with WFD. We have worked with the identified samples collected from 177 sites and with the data from 121 extra sites from projects carried out in the Ebro basin and in Catalonia. IMF includes tolerance values and ecological range of 124 taxa (50 angiosperms, 31 alg, 30 mosses, 8 liverworts and 5 pteridophytes). IMF scores are obtained from the Zelinka and Marvan's (1961) formula and the value is then assigned to the corresponding quality class according to the WFD. This assignment is based on the fluvial group to whom the sampling site corresponds. Each group includes several Mediterranean river types based on their similarity of macrophyte inventories and for each of them the reference values and thresholds between quality classes have been calculated. The IMF has been correlated with other macrophyte indices, as well as with hydromorphological indices and physicochemical variables. Most of the correlations are significant and the obtained coefficients are high. In addition, the IMF is able to statistically discriminate reference sites from perturbed sites in most of the fluvial groups. Moreover, if the indices contained in the Water Planning Instruction (Ministerial Order ARM/2656/2008, 10 September) are applied, the IMF shows a high discrimination efficiency between sites with good or higher ecological status and the rest. Therefore, the IMF is proposed as an effective ecological tool to assess the ecological status of Mediterranean rivers. © Asociación Ibérica de Limnología Madrid.

Ibanez C.,IRTA Aquatic Ecosystems | Caiola N.,IRTA Aquatic Ecosystems | Rovira A.,IRTA Aquatic Ecosystems | Real M.,United Research Services Espana
Science of the Total Environment | Year: 2012

The lower Ebro River (Catalonia, Spain) has recently undergone a regime shift from a phytoplankton to a macrophyte-dominated system. Macrophytes started to spread at the end of the 1990s and since 2002 artificial floods (flushing flows) of short duration (1-2 days) are released from the Riba-roja dam once or twice a year in order to reduce macrophyte density. The aim of this study was to analyse the spatiotemporal trends of the submerged macrophytes in two stretches of the lower Ebro River using high-resolution hydroacoustic methods, in order to elucidate the effects of artificial floods and natural floods on its distribution and abundance. Results showed that the mean cover in the two studied stretches (Móra and Ginestar) was not reduced after a flushing flow (from 36.59% to 55.85% in Móra, and from 21.18% to 21.05% in Ginestar), but it was greatly reduced after the natural flood (down to 9.79% in Móra and 2.04% in Ginestar); surprisingly the cover increased in Móra after the artificial flood. In order to increase the efficiency of floods in controlling macrophyte spreading, the magnitude and frequency of them should largely increase, as well as the suspended sediment load, approaching as much as possible to the original flood pattern before dam construction. Hydroacoustic methods combined with geostatistics and interpolation in GIS can accurately monitor spatiotemporal trends of submerged macrophytes in large rivers. This is the first article to apply this monitoring system to submerged macrophytes in rivers. © 2012 Elsevier B.V.

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