Armed with scoop nets and shod in Wellington boots, a small army of young naturalists and their parents waded into the shallows of Bibra Lake and searched for living things in the water. After good rains this winter, the lake was full, and the water was full of insect larvae and other invertebrates as well as tadpoles. We were also treated to a close-up view of insects above the water, in the form of dragonflies and damselflies clinging to sedges. Clicking Frogs (Crinia glauerti) were heard calling, and we managed to find one in shallow water on the edge of the lake.

Young Naturalists at Cockburn Wetlands Environment Centre, Photo: Mike Gregson

Back at the Centre, the education officer Denise Crosby emptied the buckets into trays and helped us to examine the creatures using binocular microscopes. We used spoons and pipettes to place the tiny animals into Petri dishes. Using books, charts and dichotomous keys, we were able to identify most of the creatures.

There were the tadpoles of Clicking Frogs and Banjo Frogs. There were water fleas and their eggs, and ostracods. We identified the larvae of dragonflies, damselflies and mosquitoes. There were water boatmen, backswimmers and water beetles. There were also fresh water snails. No wonder so many water birds can survive on the lake, with such plentiful live food in the water.

Luckily, there were none of the introduced Gambusia fish that often dominate in netting attempts. Denise said this was because they would not have survived the very dry previous season when the lake dried out completely. The native animals have eggs that survive desiccation in the dry lake bed. The children found this activity fascinating, and were absorbed in discovering such a variety of creatures.

Mike Gregson