Introduction:

Riffle beetles are aquatic organisms frequently associated with well-oxygenated clean running water. However, some genera of Elmidae can also be found in moderately polluted streams proving their tolerance to certain degree of habitat degradation.

Objective:

To determine the pollution sensitivity and tolerance of each genus of Elmidae in Colombian streams, and the main factors that influence its presence and taxonomic composition.

Methods:

Sixty locations between 450 and 4 000 m.a.s.l. were sampled, mainly in the Andean Region of Colombia. Collection was carried out between 2002 and 2013 with 70 non-simultaneous events in five zones. In a 100 m transect, physicochemical, bacteriological and environmental quality information was recorded. Samples of Elmidae were collected with D and Surber nets and determined taxonomically. A Canonical Correspondence Analysis of the Elmidae assembly and environmental data was carried out, significant relationships were confirmed with a Mantel test and a partial Mantel test was carried out including the geographic location as the third matrix. The Pollution (ICO) and Water Quality (ICA-NSF) Indices were calculated, and the occurrence intervals by genus were plotted for environmental variables and indices. Analysis of Variance ANOVA, Student’s t-test and Generalized Linear Models GLM with Poisson distribution, were calculated in order to establish the significance of the results.

Results:

Twenty-two genera and 15 species were found in the evaluated streams; which represent 78.5 % of known national generic richness. Tyletelmis and the species Gyrelmispusio, G. simplex, Xenelmis sandersoni, X. leechi, X. granatoides and X. teres correspond to new records for Colombia. The most important factors influencing the presence and composition of Elmidae were: oxygen saturation, sediment deposition, suspended solids, epifaunal substrate availability, altitude and geographic location, conductivity, turbidity, alkalinity, nitrates, ammonia nitrogen and phosphorus.

Conclusions:

The genera of Elmidae differ in their tolerance to contamination and therefore cannot be classified in the same degree of sensitivity. This information can be useful for classifying genera of Elmidae according to their sensitivity to changes in environmental conditions and habitat degradation, which will be a first step to incorporate Elmidae in water quality biotic indices adapted to local conditions or to adjust preexisting indices.