Collaboration Key to Understanding Mangrove Health in Torres Strait

Torres Strait is home to nearly half of the world’s mangrove species within an area of some 31,390 Ha. However, Torres Strait mangroves are exposed to natural drivers of change, including wind, waves, storms and lightning, more so than mainland mangroves. They are therefore vulnerable to climate-related effects, such as increased storm frequency and severity and coastal erosion.

Torres Strait islanders have a long and intimate knowledge of mangrove habitats, reflected in their traditions, culture and long-standing reliance on the basic benefits and resources provided, such as food fishes, wood construction products and medicinal aids. However, the collective species inventory and condition of mangrove habitats among the islands of the Torres Strait has not previously been recorded.

Tropical Ecosystems Hub researchers are working in collaboration with Rangers from the Torres Strait Regional Authority’s Land and Sea Management Unit to record the condition of mangrove habitats. The collaborative arrangement is carried out in conjunction with the activity of Project 2.2 ‘Mangrove and Freshwater Habitat Status of Torres Strait Islands’ and forms part of the broader MangroveWatch Program.

The collaboration with the LSMU Rangers and their extensive local knowledge has greatly improved understanding of mangrove biodiversity on the islands surveyed; often more than doubling existing species records. The species documented were already locally known, named and used by Traditional Owners.

The NERP project includes helicopter surveys, which have covered 463 km of shoreline on 20 islands and collected a georeferenced image database and critical baseline data. These aerial surveys have been validated by boat-based assessments or by shoreline walks at low tide guided by local knowledge. More than 170 km of shoreline on 15 islands have been surveyed by the latter methods since 2012.

The impressive spatial coverage of the project has provided researchers with a vastly improved understanding of the overall condition of mangroves in Torres Strait. The aerial surveys indicate that, whilst human impacts are minimal in most areas, direct human impacts on mangroves adjacent to townships were observed, especially localized cutting and pollutant impacts from nearby sewage treatment plants.

In a changing environment, it is increasingly important that these critical habitats are well understood and that management of these resources reflects the ecosystem services provided by them. The collaborative and complementary approach combines local and scientific knowledge to build capacity for the management of Torres Strait mangroves in the future.

Contact Dr. Damien Burrows (damien.burrows@jcu.edu.au) or Dr. Norm Duke (norman.duke@jcu.edu.au) for more information.