Coastal estuaries and chambers of secrets

18 November 2003

A team of scientists will converge this week on the Shoalhaven district in NSW to investigate nitrogen cycling in St Georges Basin. The study is part of Geoscience Australia's national focus investigating nutrient cycling in estuaries around the country.

"Estuaries are a vital part of healthy coastal environments, acting as both nurseries to juvenile marine species and filters for water before it enters the marine environment," Emma Murray from Geoscience Australia said.

"Agricultural and urban development in catchment areas can lead to excessive amounts of nutrient runoff into estuaries.

"A build up of nutrients like nitrogen may cause water quality problems such as low oxygen levels and excessive plant growth including toxic algal blooms," Murray said.

The team's study is supported by the Shoalhaven City Council.

"Good water quality in estuaries is important for maintaining the Shoalhaven's economic, ecological, and social values including fisheries, recreation, tourism and biodiversity," Shoalhaven City Mayor Greg Watson said.

"The research results will contribute valuable environmental information to guide our local management strategies such as the Urban Stormwater Management Plan," Clr Watson added.

The scientists will submerge water-monitoring chambers at five different locations on the floor of the estuary. Water samples from the chambers will be collected each hour to show how much nitrogen is released from the organic matter in the sediments below.

"Once we get the information from the different locations, we'll be able to work out how the estuary is cycling the nitrogen and how well it is coping," Emma Murray said.

"The five locations will probably show varying results as they're affected by different factors such as the type of runoff coming from the catchment and the chambers proximity to the estuary mouth.

"The final results will help determine how much nutrient loading the estuary can handle and may also help environment managers to improve water quality and determine land management practices in adjacent catchments," Murray added.

The team will also take sediment core samples to establish St Georges Basin's evolution and ecological habitats. The NSW Environment Protection Authority and Wollongong University are collaborating with Geoscience Australia in the study.

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