Postgraduate: Susan Lutton - Aquatic biodiversity and the ecological value of the ring-tank water storages on cotton farms (wasFCRC1C)
Abstract
Globally, natural wetlands are under threat from water resource development
reflecting the need to support a growing population. In the Border Rivers Catchment
in Queensland, Australia, a large irrigation industry coupled with a highly variable
flow regime has necessitated the building of large on-farm water storages and often
associated destruction or isolation of their natural counterparts. With the decline in
abundance of natural wetlands, the presence of these storages on the floodplain has
raised the question of their suitability as alternative aquatic habitat. This project
aimed to investigate the diversity of storages and the structure and function of the
aquatic assemblages they support compared with nearby natural wetlands. These
results were then used to recommend best management practice for optimising both
diversity and ecosystem function in storages.
Initially the physical variety of water storages in the Border Rivers Catchment was
described and their morphology and hydrology compared to that of natural wetlands.
Storages and natural wetlands formed two distinct groups based on morphology.
Storages tended to be large, deep structures with a more regular shape, while natural
wetlands were irregular and shallow with large perimeters. Although there was a
degree of variability amongst storage sites, most fell into one group and were
considered to be a ‘typical’ storage in this region.
Storages primarily function as water supplies and their associated management makes
them mostly unsuitable as ‘replacement’ wetlands. However, given the large numbers
of storages across the catchment, if managed effectively, they may provide an
additional source of aquatic habitat and help maintain regional biodiversity. To
maximise the biodiversity of storages it will be essential to reduce the morphological
homogeneity of storages across the landscape and increase habitat diversity within
storages. In the future, improved design of new storages and alterations to existing
storages and their management could help overcome this problem of low diversity of
habitat.
As a group, storages in the Border Rivers Catchment are still fundamentally different
to natural waterbodies, with storages being a mostly homogeneous group. If we are to
sustain the aquatic biodiversity in the Border Rivers Catchment and other similar
irrigation regions it will be necessary to preserve the spatial and temporal variation in
habitat evident in natural wetlands.
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- 2008 Final Reports
CRDC Final Reports submitted in 2008