Tadpole Experiments

As I'm close to completing my degree, in February I started my dissertation project, a 30-credit final year module on environmental science. I get to choose my own project, as long as it compares biotic and abiotic factors. I have chosen to study common frog tadpole hatching success at different levels of water acidity. This follows on from my second year project where I did some fieldwork in a local nature reserve, and found that amphibians were absent from one particularly acidic pond. After some literature research, I have set up a home experiments to assess at what point acidity is lethal, and at which point it can develop into frog spawn. Is there a tipping points or a gradient along which acid impacts development?  The last few weeks have been quite intense in planning and setting up the experiment.  I had to get approval from the module team early, as the deadline for my first assignment isn't for another ten days, but the frogs arrived in my pond in mid-February.  I am at a slight disadvantage as I am having to cram a lot of work up front, but it will mean that my data collection is over relatively quickly and I have the summer to write up and get involved in other conservation tasks.

Yesterday, activity in the pond increased and the first clump of spawn was laid. This happened at lunchtime, just as I was about to set off for an overnight trip. As I had committed to collect spawn within 24 hours of it being laid, needless to say my trip was delayed while I collected the spawn and decanted it into separate tanks.

First I split the clump of frog spawn into four different batches.  This was much harder than I imagined as the jelly stuck the eggs together very firmly. Three smaller clumps were put into my least acidic water to acclimitise, then two of the clumps were gradually moved to more acidic water.  One of the four clumps was returned to the pond.

The experiment has only been running a day and so it's not really possible to see if there is a difference between the spawn in the different water treatments.  The one in the most acidic water does look slightly more cloudy, but this could be my imagination. There are a couple of deformed eggs, but these occur in different treatments so it is not necessarily the acid that has caused it - it could have been damaged whilst I was splitting the spawn.

Hopefully the frogs will produce more spawn in the coming days as I need to carry out at least three replicates of the experiment. I am trying to photograph the spawn at different stages so hopefully there will be some interesting photos posted here over the coming weeks.