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Fish use of the flooded margins of an intermittently open estuary in South Eastern Australia.
Author(s) Becker, A., Deakin University
Laurenson, L. J., Deakin University
Jones, P. L., Deakin University
Type Oral
Session CPS-06 - Fish ecology and fisheries
Time & Place Monday, 09:00 am in Marriot Room 5 (subject to change)
 
The formation of a sand bar and closure to the ocean is a common feature of estuaries in temperate regions of Australia. Following closure many estuaries begin to flood providing a new habitat for fish that offers cover and rich food sources. The Surrey Estuary, located in southwest Victoria, Australia, follows predictable seasonal patterns of mouth closure and flooding. The mouth is often opened artificially if waters flood surrounding infrastructure and pastures. The use of flooded margins of intermittently open estuaries, particularly by fish, is relatively unknown and it may be that these are important habitats for foraging and protection from predation. Artificial opening of the mouth could therefore result in significant habitat loss for estuarine fish. Monthly water quality sampling has revealed the estuary is prone to significant stratification with deeper waters within the main channel becoming anoxic during late summer and autumn. During times of stratification it is hypothesized that flooded margins become increasingly important due to loss of demersal habitat within the main channel. Preliminary results indicate that the majority of fish species within the estuary frequently utilize the flooded margins. While the flooded margins provide protection from large piscivorous predators smaller piscivorous species have found to be prevalent throughout the flooded zones.