A biometric and ecologic comparison between Artemia from Mexico and Chile.
BACKGROUND
A preliminary biometric and ecologic database for the brine shrimp Artemia from Mexico and Chile is presented. The area abounds in small and seasonal ponds and large inland lakes, the latter mainly located in Mexico, although relatively large and isolated lakes are found in complex hydrological settings in pre-high plateau areas of Chile. This paper summarizes research efforts aimed at the localization, characterization, and evaluation of the aquaculture potential of Artemia populations in Mexico and Chile, which exhibit great habitat diversity (ponds, salterns, coastal lagoons, sea arms, coastal and inland lakes), contrasting weather conditions and different levels of isolation and human intervention.


RESULTS
This study covered locations between 29 degrees north latitude (Baja California, Mexico) to 50 degrees south latitude (Puerto Natales, Chile). Biological characteristics considered are species name, reproductive mode, cyst diameter, chorion thickness, and nauplius length, whereas ecological data include pond size, pH, salinity, temperature, and water ionic composition. Artemia franciscana is the only species found in Mexico, it exists together with A. persimilis in Chile, though separated geographically. Ecological differences in habitat exist between both regions but also within countries, a pattern particularly clear with regard to water composition. Surprisingly, a Mexican (Cuatro Ciénegas, A. franciscana) and a Chilean location (Torres del Paine, A. persimilis) share habitat characteristics, at least for the period when data were collected. The discriminant analysis for cyst diameter and nauplius length shows that Artemia from only one location match in cyst diameter with those from San Francisco Bay (SFB) (Point Lobos), and one (Marquez) is far apart from SFB and all the others. The Chilean locations (Pampilla, Cejar, Cahuil, Llamara, Yape) share cyst diameter, but tend to differ from SFB. The remaining Mexican locations (Juchitan, Ohuira, Yavaros) are well separated from all the others. With regard to nauplii length, populations tend to distribute in a relatively random manner, being Marquez the location differing the most in cyst diameter from SFB.


CONCLUSIONS
This database will contribute to the knowledge of radiation centers and serves as a baseline for further biogeographic studies, population characterization, management, and monitoring of Artemia biodiversity. Likewise, the impact of colonization and translocations for aquaculture purposes can be better assessed with a baseline for reference. Mexico and Chile exemplify the need to increase and further integrate regional information to tackle fundamental problems underlying practical utilization of Artemia.
Castro
Thalía B
TB
Universidad Autónoma Metropolitana-Xochimilco. Departamento "El Hombre y su Ambiente Calzada del Hueso No.1100. Col. Villa Quietud 04960, D.F., Mexico.
Gajardo
Gonzalo
G
Laboratory of Genetics & Aquaculture, Department of Basic Sciences. Universidad de los Lagos, Osorno, Chile.
Castro
Jorge M
JM
Universidad Autónoma Metropolitana-Xochimilco. Departamento "El Hombre y su Ambiente Calzada del Hueso No.1100. Col. Villa Quietud 04960, D.F., Mexico.
Castro
Germán M
GM
Universidad Autónoma Metropolitana-Xochimilco. Departamento "El Hombre y su Ambiente Calzada del Hueso No.1100. Col. Villa Quietud 04960, D.F., Mexico.