The Torres Strait lies between Australia’s Cape York Peninsula and Papua New Guinea, is a shallow (mostly 10-20m depth) body of water 100 km long and 250-260 km wide (east-west) formed by a drowned land ridge extending from Cape York to Papua New Guinea.

There are more than 100 islands in the Torres Strait, which stretches over a total area of 35 000 square kilometres. Of these, approximately seventeen are inhabited. Reefs are generally aligned east-west, streamlined by the high velocity tidal currents that pour through the inter-reef channels.

Seagrass communities occur across the open sea floor, on reef flats and subtidally adjacent to continental islands. A well defined line of large reefs runs northwards from Cape York, including the Warrior Reefs with extensive seagrass-covered reef flats. Mixed species occur on these flats; most commonly of the genera Halodule, Thalassia, Thalassodendron and Cymodocea. The large expanses of open water bottom are covered with either sparsely distributed Halophila or mixed species (Halodule, Thalassia and Syringodium) communities. Lush Halophila ovalis and Halophila spinulosa communities are also found in the deep waters (>30m) of the south-western Torres Strait.

Although Torres Strait has some of the most extensive seagrass meadows in northern Australia, and supports populations of threatened species and critical fisheries resources, little however is known about the seasonal trends that these meadows undergo.

The dynamics of tropical seagrasses are heavily influenced by weather patterns, flood and cyclone events. Our ability to predict the consequences of such disturbance on different seagrass habitats requires ongoing collection of monitoring information on seagrass habitat condition useful for government agencies and communities to make management decisions regarding these important resources.