Aplicación de los peces como indicadores en la cuenca del Ebro en cumplimiento de la Directiva marco del agua

Fish indices are an excellent tool for the assessment of ecological status and for river management. We computed three fish indices (IBICAT2b, IBICAT2010 and EFI+) and validated them with the relationship to environmental pressures (e.g., water quality, indicators of hydrological alteration and land use changes) for 369 sites across the Ebro river basin. The three indices are significantly intercorrelated and explain 26-37% of the variation in anthropogenic perturbation: IBICAT2b explains the most and IBICAT2010 the least. Most explained variation is not due to unique pressures (e.g. water quality) but to joint variation (e.g. land use changes that are associated to poorer water quality and hydrological alteration). IBICAT2010 (which in the Ebro seems to be identical to IBIMED, except for the final thresholds of ecological status) responds less well to anthropogenic pressures than IBICAT2b and EFI+. Moreover, IBICAT2010 has several methodological flaws, e.g.: a typology developed with data only from Catalonia that does not seem to work well in the rest of the Ebro; and unjustified, and often inadequate assignment of “bad” status to sites that are dry or apparently fishless. Therefore, IBICAT2010 o IBIMED is not recommended for application in the Ebro. The percentages of introduced species or individuals are correlated to the fish indices and similarly to them, change downstream and are significantly related to most pressures (land use changes, hydrological alteration, and water quality) ​
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