Estuaries provide critical ecosystem services but are threatened by natural and human pressures. Assessing their ecological condition is essential to evaluate future change. This study aimed to determine the biodiversity of macrobenthic invertebrates and potential environmental drivers in four estuaries between two timepoints. Following the significant 2022 flood events on the north coast of NSW Australia, we used benthic cores to sample the macrofauna in 2023, replicating a baseline survey undertaken in 2007. Four replicate samples were taken at three tidal heights (all <1m) on sand banks in the mid-estuary zone at Brunswick, Sandon, Corindi and Bellinger Rivers. Macroinvertebrates (>1mm) were sorted, identified, counted and categorised into functional groups. The abundance and species richness of macrobenthic invertebrates was significantly lower in 2023 compared to 2007. Macrobenthic diversity and community composition showed significant changes between years, among estuaries. The bivalve Mysella vitrea (Lasaeidae) was the most abundant species, primarily explaining the dissimilarity between years. Deposit feeders dominated the functional groups, but their percentage was lower in 2023 compared to 2007. Differences in the environmental condition at the sites between two years reflect higher rain runoff in 2023, including significantly lower salinity and higher turbidity. Distance-based linear modelling showed that turbidity correlated significantly with the changes in community structure at the family level. The BEST model included a mix of physicochemical parameters, turbidity and % organic matter and explained 94.8% of the variation in community structure, suggesting that freshwater and sediment run-off may influence macrobenthic communities in these estuaries. Results from this study support previous findings highlighting the problem of lack of data to document shifting baselines and the need for regular monitoring of estuarine ecosystems.
Details
Title
Assessing changes between two years in macrobenthic invertebrate communities in four sub-tropical Australian estuaries
Creators
Muhammad M. Islami - Southern Cross University
Adam Davey - University of Tasmania
Stephen D.A. Smith - Southern Cross University
Victoria J. Cole - NSW Department of Primary Industries and Regional Development (Taylors Beach)
Rachel Przeslawski - Southern Cross University
Kirsten Benkendorff - Southern Cross University
Publication Details
Regional studies in marine science, Vol.85, pp.1-12
Publisher
Elsevier B.V
Number of pages
12
Grant note
This research has been supported by the NSW Estuary Asset Protection Program, part of the Riparian Stabilisation Package co-funded by the Australian and NSW Governments under Disaster Recovery Funding Arrangements.