icolls - Sustainable Tourism CRC

ECOLOGY, THREATS AND MANAGEMENT OPTIONS FOR SMALL ESTUARIES AND ICOLLS
ABSTRACT
Over 60% of south-eastern Australia’s coastal waterways can be classified as intermittently closed and open
lakes and lagoons (ICOLLs). At present, very little is known about the recreational use of ICOLLs and how such
use varies geographically and temporally along the New South Wales coast. The impacts of tourism on natural
environments are of increasing concern in Australia, especially in coastal areas, so it is timely that we investigate
ICOLL ecology in conjunction with tourist use patterns to ensure that these systems are appreciated, used
appropriately and managed sustainably.
In comparison with large estuaries, relatively little is known of the ecology of these intermittently open
systems and their responses to perturbations. This lack of knowledge of how these systems respond to
anthropogenic activities threatens their long-term sustainability, particularly in light of the high human
population density in coastal regions of Australia and increasing nutrient inputs from urban (sewage), industrial
and agricultural sources. In addition, local management agencies often artificially alter the opening and closing
regimes of ICOLLs to minimise the aesthetic effects of algal blooms and local flooding. In addition to these
watershed scale perturbations, ICOLLs can be significant sites for recreation and fishing activities in the coastal
zone, yet we know little about the effects of these activities on ICOLL health.
In this study we investigated critical aspects of ICOLL ecology and asked: how do these systems respond to
increasing coastal pressures in general and in particular, those directly or indirectly related to tourism and
recreation in their catchments? We used a variety of mechanisms to tackle this question, ranging from detailed
literature reviews of ICOLL responses to perturbations, to field investigations of ICOLL characteristics and fish
assemblages, food web structure and sources of carbon (energy) fuelling ICOLL productivity. We were
particularly interested in the influence of nutrient inputs (particularly from STPs) and entrance opening and
closing regimes on the basic structure of the food web and in turn, the implications of these modifications for the
sustainability and tourism appeal of ICOLLs. Specifically, we focused on aspects of the fish communities of
ICOLLs, particularly the diets of commercially and recreationally valuable species like Yellowfin Bream
(Acanthopagrus australis), Sand Whiting (Sillago ciliata), Dusky Flathead (Platycephalus fuscus) and Sea
Mullet (Mugil cephalus).
We found that ICOLLs tend to support a wide array of invertebrate and fish taxa and that diversity and the
functioning of ICOLL food webs are strongly influenced by entrance opening and closing regimes. Furthermore,
the diets of valuable fish species tended to be narrower in our study ICOLLs than in larger estuaries, highlighting
dramatically different resource use patterns in these dynamic coastal waterbodies. The sustainability of ICOLLs
for tourism and recreation is increasingly threatened by coastal developments and our research highlights the
importance of maintaining ICOLLs as fish nursery grounds and significant recreational fishing sites along the
Australian coastline.
ACKNOWLEDGEMENTS
The Sustainable Tourism Cooperative Research Centre, an Australian government initiative, funded this
research.
The Centre for Riverine Landscapes and Griffith University also supported this research through provision of
expertise and equipment required for the field and laboratory work.
The direction and outcomes of the project benefited greatly due to contributions from Professor Leon Zann
(formerly of Southern Cross University), Dr David Rissik (NSW DIPNR now DEC), Chistopher Irons (Griffith
University) and Peter Helman (Southern Cross University). In addition, Grant Russell made major contributions
to the study, particularly the work reported in Chapter 4, during his eight week summer scholarship in the Centre
for Riverine Landscapes at Griffith University.
Field assistance from Grant Russell, Steve Mackay, Kim Markwell, Nerida Beard, Christy Fellows, Andrew
Cook, Kate Smolders, Katrina Goudkemp, Ellie Dores and Kate Lawrance was greatly appreciated. Rene
Diocares provided technical support and ran the stable isotope samples through the Mass Spectrometer.
Laboratory and analytical assistance from Vanessa Fry was also beneficial.
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