Environmental quality evaluation of alpine springs in nw italy using benthic diatoms

This study was undertaken to obtain a picture of the environmental quality of 6 springs in the Ligurian Alps, situated within the Natural Reserve of the Upper Pesio and Tanaro Valleys in the Piemonte Region of NW Italy. Benthic diatom communities were sampled in Spring, Summer and Autumn of 2001. Based on 98 identified taxa, diatom indices were calculated and statistical analyses were undertaken to integrate the information derived from the known ecological preferences of the diatoms. During the summer, activities, such as sheep and cattle pastures, water abstraction and recreation intensify. The EPI-D (Eutrophication Pollution Index—Diatoms) for all samples was calculated on the basis of the diatom communities. With few exceptions, the index was always within the first quality class. An index based on the proportion of motile diatom species (belonging to the genera Navicula, Nitzschia and Surirella) was adopted in this work. It indicated a slight degree of impact, in part caused by human activities, in two springs. The causes were ascribed to a combination of pasture and recreational activities. The Classification (TWINSPAN) and Ordination (CA) of diatom species distinguished 2 different pH preferences groups, while analyses by means of circle of correlations separated environmental variables and sample groups. The use of diatoms proved to be appropriate for the evaluation of springs and high altitude mountain brooks of the type considered in the present study. This important application could be used in the management of aquatic environments in alpine regions, including protected areas, where other standardized methods (including those based on macroinvertebrates) are difficult or impossible to use.