Imagine your life as an Ostrea angasi oyster, also known as the Australian flat oyster. This incredible creature plays a vital role in our marine ecosystems, acting as a habitat engineer and ocean janitor by filtering water. While their lives may seem boring, latching onto rocks and holding on for dear life, they actually face multiple hardships and extreme events every day. So, let me take you through a typical day of an Ostrea angasi oyster.
Morning Routine as the Tide Retreats
As the tide retreats in the morning, the oyster is left exposed to the drying air. Extreme heat threatens to dry out and overheat its body as the sun removes the moisture these creatures need to survive. The oyster will clamp its shell tightly shut, conserving water and preventing its delicate tissues from desiccation. The only relief comes when strong crashing waves arrive around midday.
Midday Mayhem; Wild Whirling Waves
These whirling waves provide relief from the drying sun and wind, cooling the Australian flat oyster down and providing nutrients for their survival. However these waves also pose a set of new challenges. The returning waves can be highly turbulent, threatening to dislodge these oysters from their rocky homes. As such, the Australian flat oyster must cling tightly with its shell. This not only ensures their survival but also reduces erosion, acting as natural coastal protection.
This cycle of sun exposure and crashing waves repeats daily throughout their lives, presenting constant challenges for these resilient oysters.
Climate Change and its Catastrophic Conditions
With climate change and all its associated issues, including rising maximum temperatures, increasingly severe storms, and more variable climatic conditions, the safety of these essential creatures is not to be overlooked. Prolonged heat waves can push oysters beyond their thermal limits, while stronger and more frequent storms can rip them from their habitats. The cycles that the Australian flat oyster have learnt to adapt to for years are quickly becoming increasingly erratic, making survival even harder.
Image: Australian flat oyster mounted to a concrete block during a Melbourne University masters experiment on Ostera angasi oysters and mangrove co-habitation. Image by Georgia Walsh
Shelling out the Truth: the importance of Ostrea angasi oysters
But why should we care about Australian flat oysters? These creatures are native to the southern coast of Australia, spanning from NSW to WA! They play a vital role in the marine intertidal food chains, serving as a food source for fish, crabs, birds, parasites, and even humans. Moreover, they are exceptional filter feeders, processing large quantities of water, feeding on phytoplankton, and removing particles, algae, and even some pollutants. In addition, when found in groups, they form complex structures that provide habitats for marine organisms and protect the landscape from erosion. As such, they contribute to the health of their environments.
These hermaphroditic creatures, living their unassuming lives, are anything but simple. They endure daily trials and quietly support the health of our ecosystems. However, as climate change continues to alter their world, it’s crucial that we recognise their importance and take action to protect them.
Written by intern Sarah Carrington
If you would like to learn more about the huge diversity of life that can be found along our coasts and shorelines, please contact our Education Director at education@dolphinresearch.org.au for a public event, school holiday program or school incursion/excursion.
