Imposex
Imposex is a disorder in
Imposex inducing substances
It was believed that the only inducer of imposex was
Abnormalities
In the dog whelk, the growth of a penis in imposex females gradually blocks the oviduct, although ovule production continues. An imposex female dog whelk passes through several stages of penis growth before it becomes unable to maintain a constant production of ovules. Later stages of imposex lead to sterility and the premature death of the females of reproductive age, which can adversely affect the entire population.[4]
In 1993, Scientists from the Plymouth Marine Laboratory found a thriving dog-whelk population in the Dumpton Gap, near Ramsgate in the UK despite high levels of TBT in the water.[7] In the Dumpton Gap population, only 25% of females showed any significant signs of imposex, while 10% of males were characterized by the absence of a penis or an undersized penis, with incomplete development of the vas deferens and prostate. After further experiments, scientists concluded that "Dumpton Syndrome" was a genetic selection caused by high TBT levels. TBT-resistance was improved at the cost of lower reproductive fitness.
Biomonitoring
The imposex stages of female dog whelks and other molluscs (including
A ban on tributyltin was implemented in Canada in 2003, however, in 2006, dog whelks with imposex could still be found on the shores of Halifax Harbour in Nova Scotia.[8]
See also
- Environmental issues with paint
References
- Gibbs, P.E., Bryan, G.W. (1986). Reproductive failure in populations of the dog-whelk Nucella lapillus, caused by imposex induced by tributyltin from antifouling paints. J. Mar. Biol. Assoc. U. K. 66: 767–777.
- "Occurrence of Imposex." Natural Resource Management. 2006.
- Wirzinger, G., Vogt, C., Bachmann, J., Hasenbank, M., Liers, C., Stark, C., Ziebard, S. & Oehlmann, J. (2007). Imposex of the netted whelk Nassarius reticulatus (Prosobranchia) in Brittany along a transect from a point source. Cah. Biol. Mar. 48(1): 85–94.