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Condición somática de L. sclateri en el Guadiamar and Granado-Lorencio, 1997). The QBR index was highly correlated with both seasonal water flow and the condition indices, suggesting that the quality and quantity of riparian vegetation has a positive effect on the condition of individuals in our population. Therefore, these indicators suggest that poor habitat conditions remain in certain parts of the study area. The most influential variable in the model for parameter a (y-intercept) was pH. This variable had not been considered in other studies on Iberian barbels. Only one study that addressed the same species in reservoirs (Oliva-Paterna et al., 2003c) found a positive correlation between pH and condition. In our study area, the lowest pH values are found in the affected area, due to the input of dissolved sulphates from the pyritic mud that persists in the substrate (Van Geen et al., 1999). Furthermore, pH reduction favours the release of heavy metals retained by the substrate (Olías et al., 2005), and causes bioaccumulation in benthonic macroinvertebrates such as Procambarus clarkii and fish, especially barbel (Alcorlo et al., 2006). These studies, carried out in the Guadiamar River after the mining accident, have shown an increase in the concentration of Pb and Cd in tissues of P. clarkii and L. sclateri when samples were taken close to the spill point (Moreno-Rojas et al., 2005; Alcorlo et al., 2006). This impact gradient is coincident with other results based on physical indicators such as the depth of the toxic mud layer (Gallart et al., 1999; López-Pamo et al., 1999), or even chemical indicators, since pH increases and heavy metal concentration in water decreases as we move away from the spill point (Olías et al., 2005). In addition, the high correlation and negative relationship between pH and conductivity coincides with results from previous studies (Oliva-Paterna et al., 2003a and 2003b). Summarizing, the combination of variations in water level (seasonal water flow) and pH explain the variability in barbel condition at the Guadiamar River, with other related variables such as fish density (intra-specific density), landscape attributes (QBR), and water quality (IBG, IBMWP and conductivity) being of potential importance. The highest body condition values were found in stretches where individuals are concentrated in isolated pools, and this suggests that the remnants of the spill stop barbels form thriving in lower stretches with potentially better habitat conditions. pH values are also still significantly lower in the affected area, and this reinforces the conclusion that the variation in barbel condition at the Guadiamar River is determined, mainly, by whether they inhabit the affected area or not. Therefore, we conclude that fifty-six months after the accident, the environmental requirements 51
Las comunidades de peces del río Guadiamar y el accidente minero de Aznalcóllar needed to harbour a healthy barbel population in the Guadiamar River basin have not been reached yet. Acknowledgements This study was supported by the Guadiamar Green Corridor Research Program (PICOVER) provided by the Andalusian Regional Government. We thank Teresa Saldaña, Palmira Guarnizo, Diego García-González, Carmen García-Utrilla, Arnolf Fernández-Borlán, Carmen Arribas, Javier Berná and Rocío Pérez for their help both in the field and laboratory tasks. We also thank 3 anonymous reviewers and the Associate editor for valuable comments that greatly improved the manuscript. 52
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DEPARTAMENTO DE ZOOLOGÍA UNIVERSID
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DEPARTAMENTO DE ZOOLOGÍA UNIVERSID
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TITULO DE LA TESIS: LAS COMUNIDADES
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A mi Madre,
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A mis antiguos compañeros del Grup
Page 13 and 14: Material and Methods 39 Results 45
Page 15 and 16: ABSTRACT This PhD Thesis analyzes t
Page 17 and 18: Las comunidades de peces del río G
Page 25 and 26: ÁREA DE ESTUDIO Cuenca del río Gu
Page 27 and 28: Área de estudio Figura 1. Cuenca d
Page 29 and 30: Área de estudio farallón del Alja
Page 31 and 32: Área de estudio Principales impact
Page 34: PARTE I: Ictiofauna de la cuenca de
Page 48 and 49: II.1- Habitat quality affects the c
Page 50 and 51: Condición somática de L. sclateri
Page 54 and 55: Table 1. Mean habitat variable valu
Page 66 and 67: II.2- Habitat-fish community relati
Page 68 and 69: Relaciones peces/hábitat en el Gua
Page 76 and 77: Figure 2. Tributary network of the
Page 86: PARTE III: Evolución de la comunid
Page 99 and 100: Table 1. List of the fish species c
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Las comunidades de peces del río G
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Appendix 1. Environmental variables
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