Macroalgae and temperate rocky reefs

A recent analysis of herbarium records back to the 1940s suggests temperate seaweeds on both east and west coasts of Australia have retreated south 10-50 km per decade as waters have warmed. A recent extreme warming event (marine heatwave) in Western Australia caused substantial changes to seaweed habitats, including a reduction in large habitat forming species. In eastern Tasmania, a substantial decline in algal habitat is associated with southward expansion of a grazing sea urchin aided by the strengthening of the East Australian Current and warmer temperatures.

Warming will reduce the resilience of macroalgal habitats to other stressors such as pollution. Temperate species will contract their ranges southwards and tropical species expand their ranges further south. Many temperate species, found only in Australia, are at risk of extinction in the next 50-100 years. Extreme events (storms, heat waves, etc) will increase in frequency and magnitude and drive shifts in species’ distributions and interactions.

IMOS Autonomous Underwater Vehicle Facility will provide long-term monitoring of water properties and temperate reefs at key locations in Qld, NSW, Tas and WA. Several research projects focusing on climate change and temperate macroalgae are under way. These focus both on establishing the range of impacts as well as the mechanistic relationships which drive impacts of climate change.