Abstract
Lord Howe Rise is a marginal plateau located in the Coral Sea and Tasman Sea, composed mainly of continental fragments that detached from the eastern margin of continental Australia during the late Jurassic and Cretaceous. Lord Howe Rise is an extensive feature of the South Pacific Ocean, spanning ∼2,800 km in latitude (19°S to 43°S) and 450–650 km wide. Geomorphic features in the survey area include ridges, valleys, plateaus, and basins. Smaller superimposed features include peaks, moats, holes, polygonal furrows, scarps, and aprons. The physical structure and biological composition of the seabed were characterized using towed video and sampling of epifaunal and infaunal organisms. These deep-sea environments are dominated by thick, depositional, soft sediments (sandy mud), with local outcrops of volcanic rock and mixed gravel–boulders. Ridge, valley, and plateau environments were moderately bioturbated, but few organisms were directly observed or collected. Volcanic peaks were bathymetrically complex hard-rock structures that supported sparse distributions of suspension feeders (e.g., cold-water corals and glass sponges) and associated epifauna (e.g., crinoids and brittle stars). Isolated outcrops along the sloping edge of one ridge also supported similar assemblages, some with high localized densities of coral-dominated assemblages.
Published Version
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