Impact of natural and synthetic steroids on the survival, development and reproduction of marine copepods (Tisbe battagliai)

Given recent reports suggesting that natural and synthetic steroids (namely , oestradiol, oestrone and ethynylestradiol) may be present in sewage efflu ent at levels which may impact on fish, it is pertinent to extend the ecolo gical hazard evaluation for such substances to aquatic invertebrates. Studi es have therefore been undertaken to address whether 17 beta-oestradiol, oe strone and 17 alpha-ethynylestradiol can inhibit survival, development or r eproductive output in Tisbe battagliai (Crustacea, Copepoda, Harpacticoida) . This sexually reproducing species was selected since it is representative of a widespread group of aquatic Crustacea, is sensitive to environmental contaminants and is highly amenable to laboratory life-cycle studies. Newly released (< 24 h old) T. battagliai nauplii were exposed to individual ste roids dissolved in sea water (using the ecdysteroid, 20-hydroxyecdysone, as a positive control) and effects monitored in terms of survival, developmen t and sex ratio after 10 days at 20 +/- 1 degrees C. Adult males and female s were then paired and exposures continued to investigate effects on reprod uctive output (21 days total exposure). In summary, the lowest 21 day No Ob served Effect Concentrations based on these life-cycle parameters were: 20- hydroxyecdysone: 8.7 mu g.l(-1); oestrone: greater than or equal to 100 mu g.l(-1); 17 beta-oestradiol: greater than or equal to 100 mu g.l(-1); and 1 7 alpha-ethynylestradiol: greater than or equal to 100 mu g.l(-1) (all. bas ed on nominal concentrations). These data are relevant for the development of an ecological risk assessment for oestrogenic steroids in the aquatic en vironment and should be extended to other invertebrate groups. As novel ana lytical techniques allow, future bioassay studies should be ideally support ed by steroid analyses wherever possible. (C) 1999 Elsevier Science B.V. Al l rights reserved.