Assessing water quality in a tropical lake using biomarkers in zebrafish embryos : Developmental toxicity and stress protein responses

• Published in: Environmental monitoring and assessment 2005-05, Vol.104 (1-3), p.171-187
• Main Authors: HALLARE, A. V, PAGULAYAN, R, LACDAN, N, KOHLER, H.-R, TRIEBSKORN, R
• Format: Article
• Language: English
• Subjects: Animal and plant ecology; Animal, plant and microbial ecology; Animals; Applied ecology; Aquatic animals; Biological and medical sciences; Biomarkers; Biomarkers - analysis; Biota; Danio rerio; Ecotoxicology, biological effects of pollution; Embryos; Environmental monitoring; Environmental Monitoring - methods; Fish; Fresh Water - analysis; Fresh water ecosystems; Freshwater; Freshwater pollution; Fundamental and applied biological sciences. Psychology; General aspects; Hatching; Heat shock proteins; HSP70 Heat-Shock Proteins - biosynthesis; Laboratories; Lakes; Mortality; Philippines; Pollutants; Pollution effects; Pollution levels; Proteins; Survival; Synecology; Teratogens; Toxicity; Tropical Climate; Tropical lakes; Water analysis; Water pollution; Water quality; Water quality assessments; Water sampling; Zebrafish - embryology; Zebrafish - metabolism
• ISSN: 0167-6369; 1573-2959
• DOI: 10.1007/s10661-005-1610-z

In order to achieve a more substantial appraisal of lake water quality, the assessment must not be based only on chemical measurements and analyses of the water itself, but even more so on the impact of existing conditions on aquatic biota. This is possible with the use of biotests or biomarkers, e.g. investigations of the developmental parameters (96-h embryotoxicity evaluate) or of the induction of heat shock proteins (proteotoxicity evaluate). To evaluate the suitability of these tests for environmental screening, fertilized zebrafish eggs were exposed to water samples collected from five sites of varying levels of stress from Laguna Lake, Philippines. Reconstituted water was used as laboratory control while water samples from a highly polluted freshwater source was used as positive control. Developmental parameters were noted and described within 48 and 96 h of exposure. Dilution experiments of the positive control were also done to further assess and compare toxicity potentials of Laguna Lake waters with those originating from a polluted freshwater. After the 96-h exposure, the levels of stress proteins (hsp 70) were determined in embryos from all exposure groups. Results showed 100% mortality in embryos exposed to undiluted positive control (PC) within only 12 h. Increasing dilution levels, however, resulted in lower mortality and lower abnormality rates. No detectable developmental differences were noted among embryos exposed to either the laboratory control or Laguna Lake waters at the end of 96 h, regardless of the source. Very high survival rates and high hatching success rates were observed in embryos exposed to lake waters as well as laboratory control, and the data did not differ significantly among the groups. Likewise, no significant malformations were noted among all developing embryos throughout the exposure period. However, the levels of heat shock proteins in the two sites located closest to Manila, the Philippine capital (Northern West Bay and Central West Bay), showed a pronounced elevation relative to the control, indicating that these stress proteins protect the embryos from the detrimental effects of pollutants in the water. Based on the 96-h early life stage (ELS) test, the water quality of the lake is good for fishery propagation despite the current levels of pollutants in the water. This finding is in accordance with the Class C status (i.e. suitable for fish growth and propagation) as given to the lake by the local environmental