The spatial influence of treated effluent in Tilligerry Creek, NSW: 15N & 13C stable isotopes in estuarine bioindicators

Tilligerry Creek, NSW, is an estuary within a marine park that receives treated effluent discharged via infiltration ponds into ground water. This project uses stable isotope analysis (SIA) of estuarine bioindicators to... [ view full abstract ]

Tilligerry Creek, NSW, is an estuary within a marine park that receives treated effluent discharged via infiltration ponds into ground water. This project uses stable isotope analysis (SIA) of estuarine bioindicators to elucidate the spatial influence of carbon and nitrogen derived from treated effluent. Estuarine organisms Avicennia marina (grey mangroves), Zostera capricorni (eelgrass & ribbonweed), epiphytic organisms (algae & protozoans), Saccostrea glomerata (Sydney rock oyster) and particulate organic matter (POM) were used as biological indicators along the banks and tidal mud flats of Tilligerry Creek estuary. The influence of treated effluent was evident within the mid-section of Tilligerry Creek at sites in close proximity to the discharge interface, with the spatial influence spanning 5-6 km in length. 15N was found to be an effective indicator for effluent, more so than 13C. SIA, especially when combined with a geographic information system, proved to be an effective tool for determining the spatial influence of discharged treated effluent. This information will contribute to a long term effluent management strategy and future environmental impact assessments undertaken for the treatment plant.