Intermittently opening estuaries are artificially opened to manage flood risk, water quality, recreational amenity, and fisheries; however, the ecological impacts of this management technique are incompletely understood. During 2001 and 2004, this study assessed the impacts of artificial openings on the macroinvertebrates of entrance barriers of intermittently opening estuaries in New South Wales (Australia). In 2001 macroinvertebrates were sampled once before artificial opening and 9 d and 25 d after reformation of the entrance barrier. A multiple before-after-control-impact analysis found that, although entrance barriers were destroyed by the artificial openings and then reformed naturally by wave action, significant interactions for taxonomic richness, density of the amphipod Paracalliope australis (Gammaridae) and density of the gastropod mollusc Aschoris victoriae (Hydrobiidae) meant that the effects of this disturbance could not be distinguished from the natural variations that occurred in unopened estuaries. Multivariate analyses found that assemblages at both opened and unopened estuaries changed from before to after the openings, and the magnitude of the dissimilarity between times varied between estuaries. In 2004, macroinvertebrates were sampled on 3 randomly selected days within each of 3 periods (before, 3 d and 42 d after) at 1 opened and 3 unopened estuaries. Asymmetrical analysis of this modified before-after-control-impact study found that the change in taxonomic richness at the opened estuary from before to after opening did not differ from temporal changes that occurred in unopened estuaries. Short-term variation (i.e. between days) in total density of macroinvertebrates and density of P. australis in the reformed entrance barrier of the opened estuary also did not differ from the variation in the control estuaries. Additionally, assemblage structure was not significantly changed by the opening and assemblages at two control estuaries were also unchanged over the same time. Individual taxa and assemblages of macroinvertebrates in entrance barriers of these intermittently open estuarine systems appear to be resilient to the habitat disturbance caused by artificial openings.

Macrofaunal community composition of ten exposed sandy beaches in northern New South Wales, Australia, appeared to correlate with beach morphodynamic state even though the data represented sampling at only a single time. Better results were obtained by using the Beach State Index (BSI) rather than the dimensionless fall velocity (?). Species number and abundance significantly increased as the BSI value increased, whereas biomass was not correlated with BSI. The New South Wales beaches had a higher species number and abundance relative to BSI than did beaches in a published review of beaches around the world.

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