Summary:
Three estuarine fish species found along Australia’s eastern coastline appear capable of withstanding substantial temperature fluctuations. Researchers at Adelaide University found that their physiological performance remained similar across habitats with markedly different temperature conditions, suggesting a broad tolerance to environmental heat.
The study, published in Global Change Biology, examined yellowfin bream (Acanthopagrus australis), sand whiting (Sillago ciliata) and tarwhine (Rhabdosargus sarba) collected from 20 sites across 15 estuaries spanning approximately 1,000 kilometres of Australia’s eastern coastline.
Researchers also exposed yellowfin bream and sand whiting to simulated marine heatwaves, increasing water temperatures by 2 °C for 14 days or 4 °C for seven days. Both species tolerated these conditions regardless of whether they originated from habitats with relatively stable or highly variable temperatures.
The results suggest that heat tolerance may be a broader characteristic of these species rather than primarily a response to local temperature conditions. Under non-heatwave conditions, sand whiting from a temperature-variable habitat also grew faster at 26 °C than at 24 °C, suggesting potential benefits from moderate warming.
However, whether similar tolerance occurs in other marine species remains uncertain, while pollution and overfishing continue to threaten Australian estuarine fisheries.
— Press Release —
Some fish might thrive in a warming climate
Adelaide University researchers have found that some estuarine fishes that live in habitats with highly variable temperatures can withstand the warmer ocean conditions expected to result from climate change.
The study shows estuarine fishes’ resilience to these extreme conditions is genetically determined.
“Climatic extremes are increasing in frequency, intensity, and duration across Earth’s biomes as a consequence of anthropogenic climate change,” said project leader Professor Ivan Nagelkerken, from Adelaide University’s School of Biological Sciences.
“In aquatic systems, climatic extremes can rapidly restructure communities, disrupt ecosystem functioning, and compromise ecosystem services, including fisheries productivity.
“Our study examined the resilience of three economically important estuarine species, which we found to be ‘thermal generalists’ with a genetic ability to withstand extreme conditions.”
The study, performed by Dr Angus Mitchell, focused on yellowfin bream, sand whiting and tarwhine due to the species’ important role in the fisheries industry.
“Yellowfin bream and sand whiting are among the most commonly caught inshore species by recreational and commercial fishers on the east coast,” Dr Mitchell said.
“They’re what people target to take home, so understanding whether they can cope with warming estuaries matters directly for the fisheries that coastal communities depend on.”
While these fishes are primed for extreme conditions, many marine habitats are already experiencing changes in species distribution due to climate change.
Read also: Zebrafish adapt to heat without fitness cost
“We’re already seeing tropical species push further south as waters warm, reshuffling which fish support local fisheries,” Professor Nagelkerken said.
“Our results suggest estuarine species with broad thermal tolerance may hold their ground, but that won’t extend to species with narrower limits such as coral reef fishes.”
Professor Nagelkerken said these results provide hope for the future but he highlighted that many other species are more sensitive to climate change.
“Many estuaries are increasingly subject to other types of human pressures, such as pollution and overfishing,” he said.
“Hence, we need to manage our estuaries well to sustain the fisheries species that are set to be more resilient to a future climate.”
Journal Reference:
Mitchell, A., D. J. Booth, S. D. Connell, T. Ravasi, and I. Nagelkerken, ‘Thermal Generalism Shapes Tolerance to Extreme Heatwaves in Estuarine Fishes’, Global Change Biology 32, 10: e71143 (2026). DOI: 10.1111/gcb.71143
Article Source:
Press Release/Material by Johnny von Einem | Adelaide University
Featured image credit: Jonathan Steinbeck
