Mesophotic benthic communities associated with a submerged palaeoshoreline in Western Australia.

Key ecological features (KEFs) are elements of Australia's Commonwealth marine environment considered to be important for biodiversity or ecosystem function, yet many KEFs are poorly researched, which can impede effective decision-making about future development and conservation. This study investigates a KEF positioned over the Last Glacial Maximum (LGM) shoreline on the northwest shelf of Australia (known as the 'Ancient Coastline at ~125m depth contour'; AC125). Seafloor bathymetry, sedimentology and benthic habitats were characterised within five study areas using multibeam sonar, sediment samples and towed video imagery.

Drill cuttings and drilling fluids (muds) transport, fate and effects near a coral reef mesophotic zone.

The study was conducted to improve knowledge and provide guidance on reducing uncertainty with impact predictions when drilling near sensitive environments. Near/Far-field hindcast modelling of cuttings/drilling fluid (mud) discharges from a floating platform was conducted, based on measured discharge amounts and durations and validated by ROV-based plume and seabed sampling. The high volume, concentration, and discharge rate water-based drilling mud discharges (mud pit dumps) were identified as the most significant dispersal risk, but longer-range movement was limited by the generation of jet-like plumes on release, which rapidly delivered muds to the seabed (80 m).

Abundant box jellyfish, Chironex sp. (Cnidaria: Cubozoa: Chirodropidae), discovered at depths of over 50 m on western Australian coastal reefs.

Box jellyfish cause human fatalities and have a life cycle and habit associated with shallow waters (<5 m) in mangrove creeks, coastal beaches, embayments. In north-western Australia, tow video and epibenthic sled surveys discovered large numbers (64 in a 1500 m tow or 0.05 m(-2)) of Chironex sp.