Estuaries are in trouble say researchers from the University of Sydney, who have recently conducted a study on estuaries on the south-east coast of Australia which was published in Nature Communications. According to their findings, estuaries in this region of the world are warming at twice the rate of oceans and the atmosphere. This poses a problem because of the key ecosystem services that estuaries provide.
Professor Pauline Ross, who leads the research group in the School of Life and Environmental Sciences, elaborated, saying: "Estuaries provide services of immense ecological and economic value. The rates of change observed in this study may also jeopardize the viability of coastal vegetation such as mangroves and saltmarsh in the coming decades and reduce their capacity to mitigate storm damage and sea-level rise."
The researchers analyzed 12 years of publicly available data from the NSW Department of Planning, Industry and the Environment. The data shows over 6200 recorded temperature observations in 166 estuaries along the coast of New South Wales in south-eastern Australia. From these observations, they found that the estuary systems experienced a 2.16-degree temperature increase on average, equivalent to approximately 0.2 degrees each year. Additionally, the study found that acidification was increasing by 0.09 pH units a year.
Researcher Dr. Elliot Scanes explained, "This is evidence that climate change has arrived in Australia; it is not a projection based on modeling, but empirical data from more than a decade of investigation. Our research shows that estuaries are particularly vulnerable to a warming environment. This is a concern not only for the marine and birdlife that rely on them but the millions of people who depend on rivers, lakes and lagoons for their livelihoods around the world."
"Our results highlight that air or ocean temperatures alone cannot be relied upon to estimate climate change in estuaries; rather, individual traits of any estuary need to be considered in the context of regional climate trends," Dr. Elliot Scanes said. "This increase in temperature is an order of magnitude faster than predicted by global ocean and atmospheric models. New models will need to be developed to help predict estuarine changes."
Such changes in estuarine temperature, acidity, and salinity will undoubtedly affect the profitability of aquaculture and wild fisheries. Over 55 million people depend on wild fisheries for their livelihood. According to Science Daily, aquaculture worldwide nets $US243.5 billion annually, “while wild fisheries, much of which occurs in estuaries, is worth $US152 billion.”
Professor Ross said: "Lagoons and rivers increased in temperature faster than creeks and lakes because they are shallower with more limited ocean exchange. This is of concern in other dry temperate zones like the Mediterranean and South Africa where many of the estuaries are similar to those studied here," she said. Sounding hopeful, she adds, "This research will help local fisheries and aquaculture to develop mitigation strategies as the climate changes."