Variabilidad morfológica y distribución ecológica de especies del género Aulacoseira (Bacillariophyceae) en cuerpos de agua del centro de México

Relative abundance and morphological variability of 4 species and 1 variety of the genus Aulacoseira (Bacillariophyceae) were analyzed in sediments from lakes with different climatic, morphometric, physicochemical and tropic level regimes. Canonical correspondence analysis and weighted average optima were used to identify the ecological preferences of each taxon. The results show that temperature, salinity and trophic level were the main environmental variables defining species distribution. The species of the genus Aulacoseira were present only in circumneutral-slightly alkaline localities with low salinity. Aulacoseira granulata was the most frequent taxon and had the higher salinity tolerance, A. ambigua reached the highest relative abundances, A. nivaloides stand out because of its affinity for cold waters, of very low salinity and trophic level. Aulacoseira ambigua, A. granulata, and A. granulata var. angustissima prefered freshwater, meso-eutrophic conditions and A. pusilla turbid waters with high phosphorus concentrations. This study provides information on the biological variability and distribution of the species within the genus in lakes from central Mexico.