Zebrafish (Danio rerio) Embryo-Larvae as a Biosensor for Water Quality Assessment

Area of Science:

• Environmental Toxicology
• Aquatic Ecotoxicology
• Biomonitoring

Background:

• Wastewater treatment plants (WWTPs) are crucial for environmental protection and public health.
• Assessing the ecotoxicological impact of WWTP influent and effluent is vital for effective water quality management.

Purpose of the Study:

• To evaluate the water quality at different stages of a municipal WWTP using zebrafish (Danio rerio) as sentinels.
• To determine the effects of WWTP influent and effluent on zebrafish embryo and larval development and health.

Main Methods:

• Zebrafish embryos and larvae were exposed to different concentrations of WWTP influent (I) and effluent (E).
• Experimental groups included control (CTRL), influent (I-100%, I-75%), and effluent (E-100%, E-75%).
• Assessed endpoints included survival, hatching rate, malformations, biometry, motility, heartbeat, fin regeneration, primordial germ cell localization, and gene expression.

Main Results:

• Subtle reductions in survival and hatching rates were observed in undiluted influent (I-100%) and effluent (E-100%).
• Increased malformations, reduced motility, and affected biometry were noted in larvae exposed to I-100% and E-100%, with E-75% showing no adverse effects.
• Influent exposure (I-100%) led to reduced heartbeat, impaired fin regeneration, and germ cell delocalization, alongside dysregulation of four specific genes (foxm1l, cenpf3b, hoxc6a, ddit3).

Conclusions:

• Zebrafish embryos and larvae are sensitive sentinels for detecting adverse effects of WWTP water.
• Effluent dilution effectively mitigates ecotoxicological impacts, highlighting the importance of treatment efficiency.
• The zebrafish model provides a valuable tool for additional assessment of WWTP performance and water quality.