Encouraging signs for NSW seagrass in warming waters

Seagrasses are vital habitats that support marine life and store carbon, but how will they respond to rising temperatures?

Fisheries Scientists have explored this question for the seagrass, Zostera muelleri (also known as eelgrass), common in estuaries from Tweed Heads on the north coast all the way down to Eden in southern NSW.

The Fisheries team from the Department of Primary Industries and Regional Development (DPIRD) tested the effects on eelgrass of water temperature elevated by 3 degrees C.

Surprisingly, the study found no consistent change in the density of seagrass, its size, or growth rate, despite the warmer water.

Instead, seasonal changes, sediment characteristics (the amount of organic matter present) and shading from dense leaves had far greater effects on seagrass growth than warmer water.

These encouraging results suggest that eelgrass on the central NSW coast can tolerate the warming expected by 2090 under future climate models.

More work is needed to test whether eelgrass might be affected by increasing water temperatures in northern NSW, where this species is getting closer to its upper temperature limit.

The research has also highlighted the importance of considering other factors that can influence seagrass growth when testing for the impacts of future climate change.

You can read the full report published in Estuaries and Coasts Journal.

This DPIRD Fisheries research was funded by the NSW Marine Estate Management Strategy Project: Estuarine habitat monitoring and threat assessment.