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Abstract

This project was developed as part of a program evaluating the potential
coupling of biological waste treatment processes at the Werribee
Treatment Complex (WTC) with the harvest of zooplankton material for
commercial use. This work specifically aimed to manipulate the
distribution of particular zooplankton species according to influent
nutrient levels.
The project was conducted on a scale that is rare for such ecological
manipulations, with the flow pattern of an operational twelve pond, 70.5
hectare sewage treatment lagoon system being drastically altered to
provide two comparable halves composed of paired ponds of similar size,
orientation, influent and capacity. The system was subsequently subjected
to a target sewage inflow level of 12 million litres a day, with the level of
flow experimentally divided equally and unequally between the halves.
Despite low and variable influent rates (due to unpredictable extrinsic
factors), different and remarkably consistent patterns developed in the
zooplankton communities for each flow regime. Zooplankton
distribution and community structure changed markedly across the
system following the alteration of flow from the original pattern. Under
conditions of equal flow, zooplankton and various environmental
concentrations - ammonia, nitrate, nitrite, phosphate and chlorophyll-a -
synchronized well between corresponding ponds. Under unequal
divisions of flow, both zooplankton and ammonia (representing a gross
measure of overall nutrient loading) showed distinct differences between
halves that directly corresponded with the new flow regimes, while
patterns for nitrate, nitrite, phosphorus and chlorophyll-a reflected these
changes by becoming increasingly disparate and chaotic.
It is suggested that these changes in distribution represent a strong
nutrient-mediated successional pattern that is overlaid on normal
zooplankton seasonal succession and short-term population cycles in
such highly eutrophic environments. The unique layout of lagoon
systems at WTC promotes the spatial expression of this pattern in contrast
to similar temporal (and smaller-scale spatial) changes documented in
previous studies. Manipulations of nutrient-mediated succession as
conducted in this thesis appear to promote distinct and predictable
changes in the character and composition of traditionally variable
zooplankton assemblages. Combined with appropriate and adjustable
harvesting regimes, these could provide the first major step towards an
optimized and sustainable product.

Item Type:	Thesis - PhD
Authors/Creators:	Doran, Niall Edward
Keywords:	Sewage sludge as feed, Zooplankton, Zooplankton
Copyright Holders:	The Author
Copyright Information:	Copyright 1999 the Author - The University is continuing to endeavour to trace the copyright owner(s) and in the meantime this item has been reproduced here in good faith. We would be pleased to hear from the copyright owner(s).
Additional Information:	Thesis (Ph.D.)--University of Tasmania, 1999. Includes bibliographical references
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