Thermal risk for inshore seagrass on the Great Barrier Reef

Cape York to Gladstone

Location

High temperatures pose a serious threat to seagrass health, but we need on-the-ground data to know what temperatures are reached and to find inshore areas that are likely at risk.

We are working with Traditional Owners to deploy temperature loggers at locations throughout the inshore Great Barrier Reef and will use the data to develop a model for predicting areas of seagrass most at risk of thermal stress.

Findings can be used to respond to high-risk temperature events, understand what is causing changes in seagrass meadow condition, and underpin management strategies such as prioritising areas for restoration.

Key points

Thermal risk for inshore seagrass on the Great Barrier Reef

BACK

Heat stress for seagrass

Climate change threatens the health of seagrass meadows in multiple ways, including increasing sea surface temperatures. High temperatures cause thermal stress by impacting processes like photosynthesis, causing leaves to burn and reducing growth, abundance, and overall resilience.

Inshore seagrasses in shallow waters are at greater risk of being exposed to very high temperatures than those in deeper waters.

Current spatial temperature data does not represent the variability occurring in shallow inshore environments along the Great Barrier Reef. In-water measured data is needed to quantify the dynamic changes and extremes in these environments where seagrass meadows are widespread.

Deploying loggers for temperature monitoring

We are partnering with Traditional Owners and Land and Sea Rangers from nine First Nations groups to deploy loggers in shallow inshore seagrass habitats between far northern Cape York and Gladstone.

The project involves:

Working with Traditional Owners to co-design the sampling strategy for each site.

Collecting temperature data at 10 locations, from temperature loggers recording every 10 minutes.

Measuring temperature across a gradient of exposure from never or rarely exposed to the air (deeper water) to more frequently exposed and higher up the shore (shallower water).

Developing a model of thermal risk.

Results of high temperatures for inshore seagrass

The team found that temperatures changed throughout the day by up to 20°C, with the highest variability generally at the most frequently exposed sites (closer to shore). Temperature generally varied less and had shorter exposure to high temperatures at sites that were rarely exposed (furthest from shore).

This monitoring is ongoing and will continue to 2026. The data will be used to develop and validate a model predicting thermal stress to seagrass. This will identify thermal stress hotspots, helping to pinpoint the extent and location of inshore seagrass areas most at risk on the Great Barrier Reef.

Project details

This project is led by Dr Catherine Collier, with support from Hayley Brien, Nicki Wilson, Lucas Langlois, Len McKenzie and Traditional Owners. This project is funded by the Great Barrier Reef Marine Park Authority.

Banner image: Kathy of Wuthathi Land and Sea Rangers photographed by TropWATER.

Images: Photos of Yuku Baja Muiliku Land and Sea Rangers are by Jazmin Ford of Yuku Baja Muiliku Land and Sea Rangers.