Posted 30 April 2011 - 03:00 PM
I hope that folk here don't think that I'm being a wowser, but I'd discourage any harvesting of fish or even of aquatic insects from streams or creeks.
The chytrid fungus that is decimating many frog species has a free stage in the water column, and it is easily caught up in water and soil samples, and even in wet boots, buckets and nets. Once it gets into a flowing water catchment it ends up spreading up and down the length of the stream/creek, and it sits there waiting for a suitable host, or for somthing to transport it to where there is a suitable host.
Isolated dams and ponds can just as easily harbour the fungus, but because they are isolated they are not quite as great a link in the chain for the spread of chytrid. Over time though even a lot of these water bodies end up infected, and the number of clean ones diminishes.
People might argue that if the fungus spreads so much, why bother trying to contain it? Well, slowing the spread gives vulnerable species more time to adapt to the fungus, and it potentially keeps the fungus out of certain unique habitats that might otherwise have a naturally low risk of contamination.
As a boy I lived in swamps and streams, blissfully unaware that the fungus had been introduced to Australia (personally, I suspect either through contaminated aquarium fish released to the wild, or through released axlotls). Sadly, these days even a kid probably needs to be taught the same sort of decontamination procedures that bushwalkers and 4WDers need to observe in order to minimise the spread of the phytothphora that is causing the loss of so many plant species in the bush.
As others have pointed out, the worms and fish that people are interested in are easily found in shops, and they're clean. They're also convenient, and they have the added benefit of not having the risk of spreading weed seeds and other nasties that might infect humans.
And most of the soil ecology that might be of interest to folk here can be found in any garden pond that has matured - nature works itself out in pretty quick time. Just take a walk and knock on a door to see if a local resident is happy to share a sample. The more local the better, because the risk of transport of novel organisms decreases with distance. If you're prepared to wait a few weeks it's not difficult to set it all up yourself - the algae, bacteria, and protozoans are free from the sky, and the adult forms of the larvae that live in aquatic soil will fly in soon enough. As long as gross parameters such as temperature, light, and water quality are taken care of, the lotus will tick along well enough without the extras, and certainly for the small amount of time that it takes for them to find their own ways to a new pond.
If anyone has their heart set on doing a David Attenborough, at least learn the disinfection procedures for equipment, for water samples, and for any fish caught. Decontaminating insects and mulm is very difficult, and probably not feasible for anyone who is not professionally set up.
On the matter of lotus, there are many US sites that detail how to care for nelumbo over winter - google will find some quickly enough. One thing that is probably useful to point out is that the bigger (and especially - deeper) the water container, the less temperature fluctuation there is around the roots. Nelumbo nucifera will even grow in deep dams where I live, and I'm further south than most in Australia!