Effects of salinity and hardness on survival of Poblana letholepis (Atheriniformes: Atherinopsidae) larvae

Document Type: Primary Research paper

Authors

Abstract

Poblana letholepis is an endemic fish from crater-lake La Preciosa, Puebla, at the Mexican Plateau, Mexico. It has been a great resource for local people since pre-Hispanic times. This species is at risk of extinction due to its habitat loss in addition to the lack of knowledge about its biology. Survival and development time of P. letholepis were evaluated from hatching to metamorphosis to juvenile, with 20 free embryoL-1 reared at 0, 4, 8, 12 and 16 gL-1 salinities and 160-180, 80-100 and 40-48 mgL-1 CaCO3, 20 ºC, pH 7.6 and 5 mgL-1 O2, under a bifactorial design (5 x 3 levels) with three replicates per treatment. Larvae were fed with rotifers (Brachionus plicatilis) and Artemia nauplii. Treatments showed differential effects on survival (ANOVA II, P < 0.05) but not in juvenile metamorphosis time (50 ± 0.25 dph) (ANOVA II, P > 0.05). Salinity presented a significative effect on final survival, only. However, there was an interaction between these factors. The highest survival was observed at 4-8 gL-1 salinity and 160-180 mgL-1 CaCO3 (80-65%) and 80-100 mgL-1 CaCO3 (60-70%). Major survival of P. letholepis larvae, is probably due to physiological mechanisms such as increased excretion of sodium by chloride cells proliferation in hard water.

Keywords