Standard Presentation (12 minutes) Australian Marine Sciences Association 2025 Conference

Looking at the Whole Picture: What Does a ‘100% mapped’ Seabed Mean for Future Management of the Temperate East’s Solitary Islands Marine Park? (119927)

Tim Ingleton 1 2 , Michael Sutherland 1 , Tom Doyle 1 2 , Michelle Linklater 1 , Brad Morris 1 , Neil Doszpot 3 , Gus Morris 4 , Sarah Hamylton 4 , Derrick Cruz 3 , Alexandra Jones 3 , Emily Harris 5
  1. New South Wales Department of Climate Change, Energy, the Environment & Water, Lidcombe, NSW, Australia
  2. University of Wollongong, Wollongong, NSW, Australia
  3. NSW Department of Climate Change, Energy, the Environment and Water, DCCEEW, Sydney, New South Wales, Australia
  4. University of Wollongong, Wollongong, NSW, Australia
  5. Marine Parks Management, Temperate East Network, Parks Australia, Department of Climate Change Energy the Environment and Water, Kingston, Tasmania, Australia

High resolution seabed data are a priority for Australia including marine parks of the Temperate East. From small, on-shelf (4km2: Cod Grounds) areas to expansive offshore domains (~188,000km2: Norfolk), to date, mapping effort has achieved ~33% of the network’s seabed (5-50m resolution). Solitary Islands (152 km2) surveys recently completed 100% coverage that, combined with towed-video/sediment sampling, provided the network’s first park-wide maps of benthic landforms, sediments, and biodiversity.

The north is dominated by peaks/reefs, while the mid and south have large areas of planar seabed and mobile sand-wave fields of high-variability backscatter. Mesophotic reefs are dominated by sponges followed by black/octocorals then bryozoans with diversity/density generally greatest in the north. For corals, branching 2D/3D-branching-forms dominated northern reefs, with hydroids, 3D-branching & stony forms more common in the central/south.

Sedimentary units, like elsewhere in NSW, transition with increased depth and distance-from-shore, from pockets of fine sands (outer nearshore zone), through lenses of medium-coarse grained inner-shelf sands/gravels, to fine muddy sands in the low-slope/energy inner-mid shelf. Carbonates (%) typically increased within the inner-shelf sands, and nearer to reefs. The distribution of soft sediment features is likely related to complex oceanography associated with the displacement of EAC-associated water masses around the park’s islands.