Importance of saltmarsh to fish species of a large south-eastern Australian estuary during a spring tide cycle
Margaret E. Platell A B and Peter Freewater AA Centre for Sustainable Use of Coasts and Catchments, School of Environmental and Life Sciences, University of Newcastle, PO Box 127, Ourimbah, NSW 2258, Australia.
B Corresponding author. Email: Margaret.Platell@newcastle.edu.au
Marine and Freshwater Research 60(9) 936-941 https://doi.org/10.1071/MF08164
Submitted: 23 May 2008 Accepted: 5 January 2009 Published: 22 September 2009
Abstract
The dietary compositions of fish species over saltmarsh in a large south-eastern Australian estuary (Brisbane Water) were explored to ascertain the importance of this habitat type to the fish community of that estuary. Following tidal inundation, 12 fish species (<120 mm total length) were obtained using fyke nets, with Ambassis jacksoniensis being particularly abundant. The stomachs of all fish contained undigested prey, implying that they fed while on the saltmarsh. Three species (A. jacksoniensis, Atherinosoma microstoma and Redigobius macrostoma) fed nearly exclusively on the crab zoeae that were released in high numbers by saltmarsh crabs. The diets of these three species significantly differed from those of the other species, which comprised mainly foraminiferans, copepods, crabs, polychaetes, terrestrial insects and/or detritus. Substantial partitioning of food resources also occurred between the other nine species. With increasing body size, A. jacksoniensis fed more on benthic prey (polychaetes and copepods) and less on crab zoeae. This study highlights the importance of saltmarsh as providing both protection and food resources for fish species during even short periods of tidal inundation by its provision of a superabundant food source (crab zoeae) and other prey, and underscores the need for recognition of saltmarsh in management plans for fish.
Additional keywords: Australia, crab zoeae, mangroves, resource partitioning, size-related changes.
Acknowledgements
We are grateful to J. Jelbart and W. Gladstone for assisting in the initial stages of this project, to T. Boyland for confirming fish identifications, and to the Editor and referees for helpful comments. Sampling was carried out in accordance with the Australian Code of Practice for the Care and Use of Animals for Scientific Purposes (2004). Funding was provided by Gosford City Council and laboratory facilities were made available by the University of Newcastle, Ourimbah Campus.
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