Second-hand toxins, an experiment on the common sole

The early stages of life are often considered the most critical, in some species of fish, this fight for life starts before they are even born. It is well documented that early life stage fish are more sensitive to toxins than their full-grown counterparts,[1] as well as the early life stages of oviparous fish species who have multiple times the normal level of exposure to pollutants accumulated by the mother fish, transferred to the egg together through lipids and proteins nourishing the unborn eggs.[2]

For this study, researchers measured the water and tissue concentrations of

lipophilic persistent organic pollutants (POPs), pollutants transferred from mother to egg, durring the development of embryos into juvenile fish.  The model organism was aquacultured common sole (Solea solea). Under conditions with mixed pollutant levels, the experiment revealed that maternally transferred highly POPs are barely excreted and reach peak concentrations at the end of the yolk-sac stage, the critical moment when the larvae has to switch to external feeding. Further study may reveal in combination with the further concentration in the developing larvae similar to seen in this study could result in extreme body burdens during critical stages of larval development, with serious consequences for larval survival, even when eggs and larvae can develop in pristine areas, with minimal pollutants absorbed post hatch.




[1] Hutchinson TH, Solbe J, Kloepper-Sams PJ. 1988. Analysis of the ECETOC aquatic toxicity

(EAT) database—III—Comparative toxicity of chemical substances to different life stages

of aquatic organisms. Chemosphere 36:129–142


[2] Russell RW, Gobas F, Haffner GD. 1999. Maternal transfer and in ovo exposure of

organochlorines in oviparous organisms: A model and field verification.  Environ Sci

Technol 33:416–420.

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