Zebrafish as a possible bioindicator of organic pollutants with effects on reproduction in drinking waters

Abstract

Organic contaminants can be detected at low concentrations in drinking water, raising concerns for human health, particularly in reproduction. In this respect, we attempted to use the zebrafish as a bioindicator to detect the possible presence of these substances in drinking water, aiming to define the most relevant parameters to detect these substances, which particularly affect the development and reproduction of zebrafish. To this end, batches of 30 embryos with the chorion intact were cultured in drinking waters from different sources, throughout their full life-cycle up to 5 months, in 20 L tanks. Six replicates were performed in all water groups, with a total of 24 aquariums. Two generations (F0 and F1) were studied and the following parameters were tested: in the F0 generation, survival and abnormality rates evaluated at 5 dpf (days post fertilization) and at 5 mpf (months post fertilization), the onset of spawning and the fertility rate from 3 mpf to 5 mpf, and the sex ratio and underdeveloped specimens at 5 mpf. Furthermore, in the F0 offspring (F1), survival and abnormality rates were evaluated at 5 dpf and the hatching rate at 72 hpf. These results revealed that the hatching rate is the most sensitive parameter to distinguish different levels of effects between waters during the early life stages, whereas the rate of underdeveloped specimens is more suitable at later life stages. Regarding adult reproduction, fertility rate was the most sensitive parameter. The possible reversibility or accumulative nature of such effects will be studied in future work.

Zebrafish as a possible bioindicator of organic pollutants in drinking waters with effects on reproduction: are effects cumulative or reversible?

“…Based upon results from our previous work (Martínez-Sales et al , 2015b), hatching rate, fertility rate and underdeveloped specimens were the most sensitive parameters to detect the possible presence of environmental pollutants in drinking waters from different tap water distribution networks (A, B and C). These parameters were selected considering the full life-cycle (from development to reproduction) of zebrafish specimens.…”

“…Hatching rate was evaluated at 72 hpf (Martínez-Sales et al , 2015b) in the F1 and F2 generations during the fourth and fifth mpf.…”

“…In our previous work (Martínez-Sales et al , 2015b), we defined and narrowed the most sensitive developmental and reproductive parameters in zebrafish, with the long-term aim of establishing the zebrafish as a bioindicator of the possible presence of environmental pollutants. Specifically, the assessment was carried out in three drinking waters from different tap water sources.…”

Discrimination of the effects on zebrafish reproduction from pollutants in drinking water via female, via male and/or via fecundation water

“…As mentioned in material and methods, in our previous work (Martínez-Sales et al, 2015) water B manifested the most harmful effects on reproductive parameters, which is the reason we have focused on this water in the present work.…”

“…The detection of organic pollutants in drinking water through the study of the most sensitive developmental and reproductive parameters in zebrafish, particularly the latter, was the aim of our last work (Martínez-Sales et at., 2015). In our current work, we attempt to elucidate the origin of the effects on survival, abnormality, hatching and fertility rate in zebrafish adults reared in two waters (Z and B) also tested in our previous works, from three different pathways: male origin, female origin or the water where the in vitro fertilization took place, with the aim of establishing the zebrafish as a bioindicator in water quality studies.…”