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

Análisis del proceso de recolonización
del tramo afectado del Guadiamar
maintained an abundant population in the study area since 2000, even though the
sampling site close to the Doñana marshland (E5) took one year longer in harboring it
(Fig 8a). This delay suggests that this species recolonized the affected reach mainly
from both the non-affected upstream areas of the main stem and the Ardachón stream
(Fig. 9). L. sclateri is a potadromous species well adapted to the unfavorable
Mediterranean summer conditions (Rodríguez-Ruiz and Granado Lorencio, 1992;
Encina et al., 2006), with high temperature in isolated pools in the upper section, and
organic matter accumulation in the lower section (Herrera y Fernández-Delgado, 1992;
Torralva et al. 1997; Doadrio et al., 2011). This intrinsic resistance to adverse
conditions makes L. sclateri the most ubiquitous and abundant species in southern
Iberian courses, withstanding the increasing pollution that other native species are not
able to face (Oliva-Paterna et al., 2003a; Encina et al., 2006; Fernández-Delgado et al.,
2007). Moreover, its fast growth rate and large size provide this species a wide mobility
and high capacity for dispersal (Saldaña, 2006), including L. sclateri in the fast
recolonist group (Scholosser, 1990; Detenbeck et al., 1992). Consequently, and in
agreement with others studies on recolonization processes (e.g. Ensign and Leftwich,
1997; Lonzarich et al., 1998; Kubach, 2011), high abundance (Sheldon and Meffe,
1995) and large mobility (Albanese, 2009) identified L. sclateri as the best colonist of
the affected reach. To a lesser extent, scarce rainfall in 2002 together with the last soil
movements (Arenas et al., 2008) hampered the southern Iberian barbel population,
especially in E3, but in the following years, the species reached stable levels (Fig. 8a).
Southern straight-mouth nase, P. willkommii, was the co-dominant species in the
upstream non-affected reach of the Guadiamar River, together with L. sclateri.
However, it was almost absent in the affected area (Table 1, Fig 8b). This native fish is
a potadromous species highly sensitive to pollution and habitat fragmentation
(Rodríguez-Ruiz and Granado-Lorencio, 1992; Doadrio et al., 2011). Furthermore, the
species’ feeding habits consist on scraping algae or macroinvertebrates fixed to the
stony riverbed (Bellido et al., 1989). Since the affected reach lacks many of those
macroinvertebrates (Solà et al., 2004; Ferreras-Romero et al., 2003) and both anthropic
pollution and sediment accumulation are still increasing (Carrascal et al., 2008), P.
willkommii will rarely recolonise the affected reach as long as this trend is not changed.
Only the stretch nearest to the upstream non-affected reach of the Guadiamar River can
currently harbor the species (Table 1). This is because upstream areas are hardly
polluted, low in sediments and have clean waters that are a source of macroinvertebrates
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