Journal of Environmental Biology

Effects of 17a-ethinylestradiol on embryo survival, hatchability and larval deformities in African catfish, Clarias gariepinus

M. Nadirah^1,2*,? M. A. B. Tajuddin¹, M. Najiah^1,2, M. Abd Ghaffar^1,2,3 and K.L. Lee¹

¹School of Fisheries and Aquaculture Sciences, Universiti Malaysia Terengganu, 21030, Terengganu, Malaysia

²Institute of Tropical Aquaculture, Universiti Malaysia Terengganu, 21030, Terengganu, Malaysia

³Marine Ecosystem Research Center, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, 43600 Bangi, Selangor, Malaysia

*Corresponding Author E-mail: nadirah@umt.edu.my

Key words

17a -Ethinylestradiol

Clarias gariepinus

Embryonic development

Hatchability

Larval deformities

Publication Data

Paper received : 16.05.2016

Revised received : 20.06.2016

Re-revised received : 12.01.2017

Accepted : 28.12.2017?

Abstract

Aim: Synthetic estrogens, such as 17a-ethinylestradiol (EE2), are common in contraceptive pills, and EE₂ levels may be present in various waterways.? As such qualitative and quantitative assessment on the impact of EE₂ on aquatic organisms are needed.? The main objective of the study was to determine the effect of EE₂ at the environmentally relevant concentrations on embryonic survival, hatchability and larval deformities in African catfish (Clarias gariepinus) cultured under laboratory conditions. ??    

Methodology: Two healthy sexually mature males and two gravid female fish weighing 0.8 to 1.0 kg were selected based on the external morphological features. They were then subjected to induced breeding with ovaprim, given at 0.25 b.wt. and 0.5 ml kg^-1 b.wt. for males and females, respectively. Eight hundred fertilized eggs (embryos) were randomly distributed into four groups with 100 eggs per group in duplicate in respective concentrations of EE2: control (0 ng l^-1), 25 ng l^-1, 50 ng l^-1 and 100 ng l^-1, each in 1000 ml glass beakers. Percentage of normal embryonic survival and abnormalities were recorded prior to hatching at 30th hour post fertilization (hpf), while 20 post-hatch larvae were sampled randomly from each group to determine the number of larvae displaying morphological deformities. ?     

Results: At 30^th hpf, only 62% of the eggs survived when incubated with 100 ng l^-1 of EE₂, while the highest survival was observed in the control group (92%). The lowest hatching success rate of 55% was seen in the 100 ng l^-1 group, which was significantly lower from the embryos exposed to 0 or 25 ng l^-1.

Interpretation: The results suggest that EE2 at 100 ng l^-1 affected the early life stages of C. gariepinus, thus, a closer monitoring on EE₂ discharge into the aquatic environments is essential.

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