Richard Marchant: This is the upper Shoalhaven site where I've been looking at platypus diet with my colleague, Tom Grant, who has used this site for many years for observation of platypus biology.
This is a series of long, quite deep pools, up to three metres deep, and consequently to look at the diet of the platypus, one needs to sample the bottom of the pools where they feed, and this can only be done by diving. You can see that the pools are very rocky, but they harbour interesting animals such as dragonflies, freshwater mussels and mayflies, and these are all part of the diet of platypus.
What I'm trying to do here is get some information on the actual denisities of these animals on the bottom. Tom in the past (30 years ago) did an excellent study on what the platypus ate, but the missing part of the picture is what is available - how much is available to the platypus. This is what I'm trying to do by collecting quantitative data from a square quadrat like this on the bottom of the river. By sampling such a quadrat at various spots on the river I can build up a picture of the density of many of the potential prey items. From that sort of data, we can get an idea of the, what we call, 'production' of aquatic insects and other invertebrates on the bottom of the river. We can match this with the known energy requirements of the platypus.
One of the ultimate aims of the whole project is to try and determine how many platypus can be supported by a given length of river.
Here I'm just processing the sample that's been taken underwater on the banks, and examining the material under the microscope.