The Duero Diatom Index (DDI) for river water quality assessment in NW Spain: design and validation

Abstract

Diatom indices developed in certain geographic regions are frequently used elsewhere, despite the strong evidence that such metrics are less useful when applied in regions other than that where species-environment relationships were originally assessed, showing that species have particular autoecological requirements in different geographic areas. The goal of this study was to develop a new metric, the Duero Diatom Index (DDI), aimed at monitoring water quality in Duero basin watercourses (NW Spain). In summer 2008 and 2009, a total of 355 epilithic diatom samples were collected following standard protocols. The 2008 samples were used to develop the DDI, whereas the samples collected during 2009 were used in the index testing. Weighted averages method was used to derive the autoecological profiles of diatoms with respect to pH, conductivity, biological oxygen demand, ammonia, nitrates, and phosphates. The optimum and tolerance values for the measured environmental variables were determined for 137 taxa with abundances and frequencies of occurrence above 1%, and subsequent trophic indicator and sensitivity values were defined for the DDI. The correlation between the observed and the diatom-inferred nutrient concentrations was highest for phosphates (ρ (S) = 0.72). Significant statistical relationship were observed between DDI values and the chemistry-based General Quality Index values (p = 0.006) and the specific pollution index (SPI) diatom metric (p = 0.04). DDI has demonstrated a better correlation with water chemistry than SPI diatom metric.

A Multimetric Benthic Macroinvertebrate Index for the Assessment of Stream Biotic Integrity in Korea

“…The metric of percent tolerant organisms in the ICI provides information on indicator species. As pointed out in some previous works, including indicator species metrics in a multimetric index has limitations with respect to wide application, because indicator species often reflect either regional or local properties of community distribution and environmental gradients [69,70]. We believe that both indices have strengths at the regional level.…”

Diatom species composition and indices for determining the ecological status of coastal Mediterranean Spanish lakes

“…The design of new and specific indices for different eco-zones is a new approach (e.g. DDI index, Ál-varez- Blanco et al, 2012). This alternative approach, even though, is time and investment consuming might be more accurate for the ecological evaluation of coastal water bodies of the Mediterranean zone.…”

“…Moreover, among the indices, there is a wide heterogeneity in their database and about the diatom species that they consider. Furthermore, their effectiveness varies depending on the ecosystem type and the eco-region (Cejudo-Figueiras, 2011;Álvarez-Blanco & al., 2011Álvarez-Blanco & al., , 2012. Nowadays, the information about the use of diatoms indices in Mediterranean standing waters is scarce.…”

Benthic Diatoms in River Biomonitoring—Present and Future Perspectives within the Water Framework Directive

“…The need to monitor water quality has led to the development of standardized sampling protocols and assessment methods, through single, simplified indices. The most widespread diatom-based indices used for water quality assessment are based on classic taxonomy, up to genus and most frequently species level [30,[66][67][68][69]. These taxonomybased diatom indices are based on diatom assemblage composition and relative abundance.…”