las comunidades de peces del río guadiamar y el accidente minero ...

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Análisis del proceso de recolonización del tramo afectado del Guadiamar Previous vs. post spill fish composition There were no clear patterns in dissimilarity between the pre-disturbance species composition (1996) and the annual post-disturbance data in the four affected sites (1999-2006, 2011). Despite an initial large difference (Jaccard’s distance = 1 in E2, E3 and E5, and 0.67 in E4) between the pre-disturbance fish composition and that of the first sampling period after the spill (1999), from 2000 onwards Jaccard’s distance tended to either decrease or increase without any clear pattern (Fig. 2). Figure 2. Comparison of fish assemblage composition at each site of the affected reach in the Guadiamar river (E2-E5) with its pre-disturbance assemblage in 1996 (Jaccard´s distance, y-axis), through time (x-axis). 87
Las comunidades de peces del río Guadiamar y el accidente minero de Aznalcóllar Abundance, species richness and diversity During the monitoring period, two species were present in all sites every year: one native, L. sclateri, accounting for 50% on average (range 30%-73%) of all CPUEs collected, and one exotic, L. gibbosus, accounting for 16% on average (range 3%-31%). L. sclateri was the dominant species, except in the reference site (E1), where it was often codominant with P. willkommii (36% of total captures). This last species was considerably less abundant in E2, and absent in the rest of the monitoring stretch. Although S. alburnoides complex was present in every sampling site, it was the least abundant native species, accounting for just over 3% of all individuals collected. It occurred in the reference site but was almost absent in the affected reach. Among the exotic species, the second most dominant was A. alburnus, accounting for 12% (range 4%-26%) of all individuals collected on average, but absent in the reference site. G. holbrooki and M. salmoides accounted for 9% on average (range 6%-13%) and 10% (range 4%-17%), respectively. M. salmoides was present in all sampling sites, whereas G. holbrooki was caught only in the affected reach. No other species accounted for more than 3% of all individuals collected at any sampling site, nevertheless, all species have also been taken into account for assemblage structure analyses. Native species richness in the reference site maintained a stable fluctuation between 2 and 4 species during the monitoring period (Table 1; Fig. 3), whereas in exotics it decreased from 4 to 1-2 (Fig. 3). In contrast, both native and exotic species richness at the affected sites increased from 0 or 1 species in 1999 to a constant fluctuation mainly between 1 and 3 (sporadically 4) species in the following years. Finally, at the end of the monitoring period (13 years after the spill), the reference site showed its maximum number of native species, whereas exotics dropped to an average value. 88
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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
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Material and Methods 39 Results 45
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ABSTRACT This PhD Thesis analyzes t
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Las comunidades de peces del río G
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ÁREA DE ESTUDIO Cuenca del río Gu
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Área de estudio Figura 1. Cuenca d
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Área de estudio farallón del Alja
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Área de estudio Principales impact
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PARTE I: Ictiofauna de la cuenca de
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II.1- Habitat quality affects the c
Page 50 and 51: Condición somática de L. sclateri
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Appendix 1. Environmental variables
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