Giralang Pond was a water body, with little emergent or submerged
vegetation, designed to trap fine sediment and buffer input of rising water
to Ginninderra Wetland downstream. Ginninderra Wetland was designed
to retain and use sediment nutrients and other potential hazardous materials
in urban run-off. Water in the Wetland was more turbid and had lower
magnesium concentration, redox potentials and dissolved oxygen
concentration than did Giralang Pond. Water temperature was a minimum
of 4 °C in the winter and reached a summer maximum of 30 °C
Giralang Pond had more organisms but fewer taxa than Ginninderra
Wetland. The greatest abundance in the pond resulted principally from
high numbers of two numerically dominant species Calamoecia sp. and
Micronecta sp.. More organisms were found in vegetated habitats of
Ginninderra Wetland than open water habitats. The number of
invertebrates and the number of taxa found in Typha domingensis did not
differ significantly from similar estimates for Schoenplectus validus,
Gambusia qffinis was the dominant predator in both water bodies. On
one occasion, G. qffinis reached population densities of 35 individuals per
m-2 . G. qffinis was five times more abundant in Gininnderra Wetland than
in Giralang Pond and also showed a preference for vegetated areas.
G. qffinis over-grazed it's prey on several occasions.
G. qffinis, invertebrate predators and prey followed a pattern of a
community in a stable predator-prey cycle. Prey in early spring increased
population numbers and then decreased when G. qffinis and other predators
increased their numbers. The pattern was further strengthened by occurring
in both areas of open water and vegetated habitat types.
| Identifer | oai:union.ndltd.org:ADTP/219108 |
| Date | January 1989 |
| Creators | Lambert, David J., n/a |
| Publisher | University of Canberra. Applied Science |
| Source Sets | Australiasian Digital Theses Program |
| Language | English |
| Detected Language | English |
| Rights | ), Copyright David J. Lambert |
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