Female Sea Snails No Longer Growing Penises Thanks to Ban on Toxic Chemical

By Breanna Draxler | January 15, 2014 11:46 am

Whelks like these were growing both male and female genitalia after being exposed to toxic TBT.

Ships in the 1960s were often coated in a chemical called TBT to prevent sea critters like snails from clinging to the hull. After researchers found that the toxic chemical caused female sea snails to grow penises (alongside equally frightening effects in other species) the stuff was banned in 2008. Now, six years later, things are starting to look up for the snails.

Fed Up With Fouling

Ship builders have long struggled with the problem of fouling, whereby mollusks and barnacles hitch onto a hull, causing boat damage and creating drag that drives up fuel costs. Starting in the 1960s, a chemical called tributyltin (TBT) was painted on ships to keep them free from aquatic hitchhikers. It was toxic and therefore did the trick, as described in a 2002 report [pdf] from the International Maritime Organization:

As a biocide in anti-fouling paint, it proved extremely effective at keeping smooth and clean the hulls of ships and boats. And when it was introduced into anti-fouling paints, it was considered less harmful than biocides used in anti-fouling systems at the time: such as DDT and arsenic.

But as the chemical began to leach off the ships and accumulate in marine environments, especially around shipping ports, scientists started seeing negative effects on aquatic plants and animals.

Shellfish and sea snail populations were hit especially hard. Female whelks, for example, started growing penises and vas deferens (the tubes that directs sperm from the testes). This left the snails sterile—a condition called “imposex.” In Australia in 2004, for example, between 43 and 100 percent of snails studied were found to be imposex.

Dr. Peter Matthiessen, an ecotoxicologist from the UK who has been researching the effects of TBT for the past three decades, told Australia’s ABC,

“Really badly contaminated populations were wiped out because the females effectively exploded because they couldn’t shed their eggs.”

Sea Snails Get Sick

As research on the toxicity of the chemical piled up, starting in the 1980s, discussions about discontinuing its use ramped up as well. Finally in 2001, officials agreed upon a ban on TBT, which took effect in 2008.

Since then, whelk populations seem to be recovering. As described in the ABC,

[Queensland marine biologist Scott] Wilson has noticed not only a reduction in the severity of the condition but also some of his study sites are for the first time showing no signs of imposex at all. He has even noticed snail populations occurring in regions where they weren’t found before.

The reduction of TBT is good news for other marine invertebrates too, such as crustaceans and sea squirts. Single-sex snails: finally an environmental story to cheer.

Image credit: Edward Westmacott/Shutterstock

CATEGORIZED UNDER: Environment, top posts
  • Don’t Even Try It!

    So we spend masses amounts of money on added shipping costs due to fuel use and scrubbing the ship’s bottoms, etc? We pollute more of the air and sea by using more fuel and other cleaning chemicals, etc. All to save some snails? Some of the snails will develop immunity to TBT over time as illustrated by their influs into other areas of habitat. The snails will survive. This is stupid. Let nature protect the snails from TBT. TBT should continue to be used in anti-fouling paints until something equally cost effective can be developed and implemented.

    • teddybowties

      haha. that snail is you dumbass. you’re just too shortsighted to see that.

    • Heimdall222

      Shouldn’t that be ‘massive’ instead of ‘masses’?

      Oh, no, wait, you meant to say that the earth is flat and that all mechanical things are evil.

      Yeah, that’s the ticket!

    • Jong W Kim

      lets be kind to our home, until we must leave. the sea snails are a lifeform which evolved over epoch, then we could wipe them out in decades. It is worrisome how some people can be so selfish. I am somewhat assured that a majority is more caring.

  • mvpeeler

    of course we now need to still deal with flame retardants, nanosilver in baby pacifiers and GMOs

    • Heimdall222

      Yes, especially the GMO’s.

      Along with the truism of the earth being flat, GMO’s are known to cause shrinkage of a certain bodily organ!

  • http://blogs.discovermagazine.com Richard Wilson

    Note that there’s a typo in your link to the chemical. It’s tributyltin, not tributylin.

    • http://blogs.discovermagazine.com Breanna Draxler

      Thanks for catching that, Richard. I’ve made the change.

  • Heimdall222

    Has anyone heard whether the LGBT folks are OK with this?

  • bud278

    There is one other issue to consider – many marine creatures hitchhike on vessels to other parts of the world and invade new territories, pushing out native species… which is worse – a declining local snail population or mass migrations that damage other biospheres?

    • Heimdall222

      Mass right-wing migrations that invade new territories cause much more damage than your average snails.

      Contrary to their (right-wingers, not snails) propaganda, we must be aware that:
      — The sun does NOT revolve around the earth.
      — The earth is NOT flat.
      — The earth was NOT created 6800 years ago.
      — GMO’s do NOT shrink a certain bodily organ.
      — Pi is NOT 3.0 even.
      — All mechanical devices are NOT evil.
      — Birth control is NOT a total abomination.
      — The Chinese are NOT our friends.
      — Right-wingers are NOT God’s Chosen People.

      That last appears to be the most bothersome for the right-wingers, since those nice Jewish folks have already called dibs on being God’s Chosen People….

  • surgeen

    Now do they use something else or they just put up with the inconvenience?

  • duelles

    My life is stressed by global warming. I live in Santa Fe, NM. I find shell fossils, and petrified wood at 7,000 ft. Now it is a desert. A high desert, but a desert. Things change and we are part of that change. Bummer!


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