Ecophysiology of Chirostoma Jordani Pisces: Atherinopsidae. Habitat Characterization and Population Dynamics in a Periurban Lake (Xochimilco, México)

Chirostoma Jordani is an endemic species of the Mexican plateau, whose population, due to anthropogenic causes, has experienced a notable decrease from 2000 to the present, putting its permanence in its natural habitat at risk. Therefore, the objectives of this research were focused on evaluating the population dynamics of C. Jordani through its size and weight distributions and growth rate during an annual cycle and on determining if there is a relationship of these processes with water quality in the study site. Monthly samplings were carried out from August to November 2014 and from February to May 2015, in the Cuemanco canal, in Xochimilco México. A total of 435 specimens were collected, the smallest sizes and weights were recorded during the months of February and April (indicating a spawning period during this time) and the largest in November. A higher growth rate was recorded in the March-May months, compared to that of August-November (0.19±0.05 and 0.04±0.03 mm/day, respectively). The water quality indicators: Temperature, oxygen dissolved, pH and nitrite, were highly significant in the spatio-temporal variation of the C. Jordani habitat and influenced the abundance and growth of the population. These results lay the foundations to explain the life and performance strategies of the C. Jordani population in Xochimilco, México and are fundamental to the future management of the species in the study area and under controlled conditions.