Population Structure of the Macrobenthic Amphipod Hyalella Azteca Saussure (Crustacea: Peracarida) on the Littoral Zone of Six Crater Lakes

Abstract

The population structure of the amphipod Hyalella azteca in the littoral zone of six crater lakes in Puebla (i.e., Alchichica, Atexcac, Quechulac, La Preciosa, Aljojuca and Tecuitlapa), Central Mexico, was studied throughout a yearly cycle. Hyalella azteca was the only species found residing in the littoral area of the lakes. Mean annual density ranged from 1042 ± 3544 ind/m 2 up to 13496 ± 20740 ind/m 2. Seasonal (dry and rainy seasons) changes did not significantly affect density. In terms of abundance, juveniles dominated (55-64%) over females (13-20%), males (10-17%), and ovigerous females (8-14%). Ovigerous females held from 1 up to 38 eggs. Sex ratio (male: female) ranged from 1:1 (1.0) to 1:3.25 (0.31). Hyalella azteca developed along the ample range of environmental conditions present in the littoral zone of the crater lakes of Puebla. No statistically significant correlations between abiotic factors and H. azteca abundance in these lakes were found.