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Measuring and managing the health of estuaries and coasts through microbial DNA

Nutrient pollution is one of the most serious challenges to the blue economy and coastal ecosystem health.

Seven of eight state and territory capital cities in Australia are situated on or near estuaries. Estuaries provide economic, social, and environmental benefit to the inhabitants of those cities and to the nation as a whole. Nutrient pollution – nitrogen and other nutrients added through agricultural runoff, industry, and population growth – is one of the most serious challenges to the long-term health of estuaries and to the coastal development it supports. Understanding the capacity of ecosystems to process added nitrogen is essential to the agencies guiding sustainable development of Australia’s coastline.

The capacity of ecosystems to process and remove nitrogen is largely determined by the natural microbial processes. As important as these microbial processes are to understand, they are equally difficult to measure and model. Accurate modelling is challenging due to the complex web of physical, chemical, and biological interactions that determine distribution and function of microbial communities. Direct measurement is laborious and cannot produce data at the resolution required by models and decision makers.

Our project aims to test the potential of environomics to provide qualitative and quantitative indicators of microbial nitrogen cycling at the spatial and temporal scales required by ecosystem managers and modellers. Across a range of estuarine environments, we are assessing correlations between rates of key microbial processes like denitrification, and molecular and chemical measures like microbial community composition, functional gene abundance and distribution, organic carbon bioavailability, and isotopic fractionation in organic nitrogen and dissolved nitrate. We collaborate with biogeochemical modellers to improve the functioning of bacterial nitrogen processes in CSIRO’s core ecosystem models and to integrate the environomic measures we develop. Through higher data resolution and better model accuracy, we aim to provide industry, government, and communities with the tools they need to manage nutrient pollution and the health of the ecosystems in which they work and live.

Project lead: Dr Kristen Karsh (Environomics FSP Postdoctoral Fellow)

This project forms a component of the Microbes and healthy waterways project led by Andrew Bissett.

Image credit: “Hobart and Derwent Estuary below” by bishib70 is licensed under CC BY-NC-ND 2.0