Short term changes in flushing of tidal creeks following culvert removal

Abstract

Structures that reduce tidal flushing impact vegetation, fish, invertebrates, and plankton in estuarine wetlands, but many studies have shown that removal or modification of structures lead to at least partial recovery of biological communities. However, few studies have reported the immediate tidal response to structural alterations. Changes in tidal ranges and creek cross-sections following culvert removal from two tidal creeks on Kooragang Island, New South Wales, Australia provide an example for managers interested in altering structures in tidal creeks. Conditions are also reported for two nearby creeks where culverts were left intact. Removal of culverts resulted in increased low-tide drainage at both creeks and dramatically increased current velocity in one creek. These changes may make habitats unsuitable for some fish and invertebrate species, while plant productivity may increase. Changes attributed to culvert removal on Kooragang Island offer some insight regarding management options for over 1,300 structures that impede tidal flow in New South Wales.