Seasonal Diversity and Morphometric Variations of Rotifers in Relation to Selected Environmental Variables from a Tropical High-Altitude Lake in Mexico

Abstract

We studied the species diversity and morphometric variations of rotifers from a high-altitude water body, the Llano reservoir, in central Mexico during September 2021 to August 2022. Samples were collected from four stations in the reservoir every month. During the study period we were able to identify 54 monogonont rotifer species of which Polyarthra vulgaris, Lecane closterocerca, Trichocerca porcellus, Lepadella patella and Keratella cochlearis were numerically the most abundant. Depending on the season, the total rotifer density varied from 250 to 2450 ind L−1. Canonical correspondence analysis (CCA) showed that the species of Trichocerca similis, Keratella cochlearis, Mytilina ventralis and Scaridium longicaudum were directly related to temperature. Using rotifer species richness and abundance data, we derived the Shannon diversity index, saprobic index and rotifer trophic state index. Data on the geometric morphometrics showed that Keratella cochlearis was found in two of the three climatic periods of the year (dry and winter), while Lecane closterocerca and Trichocerca porcellus occurred during the three climatic seasons (dry, winter and rainy) and formed three distinct clusters in relation to body size.