• Question: How will polution affect species reproduction?

    Asked by shanegalligan to Aggelos, Andrew, Eileen, Naomi, Shane on 13 Nov 2012.
    • Photo: Andrew Jackson

      Andrew Jackson answered on 13 Nov 2012:


      pollutants act in many different ways. One of the weirdest ones is that some chemicals can make shellfish like mussels, cockles and whelks change sex from female to male. These shellfish change sex throughout their life normally, but pollution can make too many males and so they cant reproduce properly. This can then lead to large collapses of the shellfish populations and can be very bad for the newer shellfish farms that have appeared in recent years. A great story of the strange world of shellfish!

    • Photo: Eileen Diskin

      Eileen Diskin answered on 16 Nov 2012:


      In lots of ways. Like Andrew says, pollution can affect whether animals are males or females. A lot of times, this happens because when people take medicines (and then pee in the toilet), a bit of the medicine ends up being flushed down the toilet. And it can end up, even after the water is treated at sewage treatment plants, in our rivers and lakes.

      Another thing that can happen is actually one of the first things that was noticed about pesticides as a pollutant. Rachel Carson (an awesome scientist!) linked pesticide use to a problem with birds eggs in the 1960s. The pesticides made the birds eggs thin – so they were much weaker. So when the adult bird was sitting on the nest, waiting for the eggs to hatch – they would break!

      She wrote about all of this in a book called ‘Silent Spring’ (‘silent’ because the birds and other animals were dying, so there was a lot less chirping and noise in the spring time). A very important book, because it sold lots of copies and made people really aware of problems related to pesticide use!

    • Photo: Naomi Elster

      Naomi Elster answered on 16 Nov 2012:


      It depends on the pollutant. Andrew and Eileen have already mentioned some of the direct ways that pollutants can change reproductive cycles, by causing shellfish to change sex and birds’ eggs to break. There are plenty of other ways that pollution can affect species reproduction – the most obvious being that if pollution is strong enough to kill off most of a species, reproduction is going to fall.

      Some chemicals are what is called teratogenic – they are harmful to a developing foetus. Thalidomide is the most famous example of this. If a pollutant was teratogenic, like some pesticides, then over generations, weaker and weaker babies would be born, which would lead to the decline of the species. Another indirect way that pollution might affect species reproduction would be if pollution destroyed an animal’s food, as animals (even humans) who are very severely malnourished or sick can’t reproduce.

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