Influence of abiotic and biotic factors on morphological variation of Keratella cochlearis (Gosse) in a small Andean lake

Abstract

Morphological variation of Keratella cochlearis was studied during a spring-summer period in a small Andean lake. Morphometry was studied in relation to temperature, food resources, cladoceran competitors and invertebrate predators. Three different morphs were recorded. We observed lack of allometric growth of the posterior spine. Absence of allometric growth could be related with the low density of a predaceous water mite and the small size of the cladocerans present in the lake. Fluctuations in lorica length and width were negatively correlated with temperature and algal biovolume. We discuss the benefits of this morphological response of Keratella in relation to environmental conditions.