Tadpole Liberation!

My tadpole experiment is going really well so far. The guys are now a few weeks old and growing fast! The average hatching time was less than two weeks. They are now eating well, and as a result there is a lot of - erm - detritus on the floor of the tank. A handy hint I got off the internet was to use a turkey baster to 'hoover' out the bottom of the tank. I'm currently doing this twice a day, and changing water every two to three days, but as soon as I turn my back they make a mess again!  It is quite a time consuming project - caring for tadpoles isn't easy!

My initial methodology was to study 50 eggs/tadpoles in different tanks. As soon as I collected the spawn I realised this was impractical, as spawn is tightly stuck together and it was impossible to count off 50 eggs without damaging them, which would affect the impact of acidity on the embryo.  So instead I split the clumps into smaller lumps, and when they hatched I randomly selected 50 tadpoles to keep and liberated the rest back to the garden pond. I did this by gradually introducing pond water to the tank to bring the acidity level back to the same neutral level as the pond. I also let the tank float in the pond for several hours so that the water was the same temperature. Once released, I kept checking on the tadpoles and they survived, so this seems to have worked well and the change in environment wasn't too much of a shock to the system. 

I managed to collect more spawn so have three replicates of the experiment running. I have good results so far, with the most acidic treatment not hatching at all, but the intermediate and least acidic treatments have little difference between them. I also took a control group sample, which is reared in untreated rain water which is neutral pH.  There are slight differences in the hatching time within the replicates, but no evident difference in hatching success. 

I have continued to run the experiment and monitor the tapoles as they grow.  I am measuring a sample of them at certain ages. By photographing them and comparing them to a known distance (in this case, 10mm graph paper stuck to the bottom of the container), it's possible to measure their length accurately using some software called Image J which is free and easy to use.  I do have a significant difference in length at three weeks old, with the tadpoles in the more acidic water being shorter.  I have had relatively few deformities and this does not seem to be related to acid.  The results aren't exactly what I was expecting, but I have plenty to talk about when I do write the experiment up.

I have taken lots of photographs and video of the tadpoles and have also started a Flickr album. It seems a shame that I won't be able to use much of this in my final report, but hopefully it will be useful to refer back to.