Saturday, December 8, 2018

Bathymetry in Australia


Flythrough movie of Gifford Marine Park, which is located 600 km east of Brisbane, Australia.
The park is situated about halfway along the Lord Howe Rise seamount chain on the western flank of the Lord Howe Rise. 
Seamounts along this chain formed from Miocene volcanism via a migrating magma source (“hotspot”) after the opening of the Tasman Sea. 
Two large, flat-topped volcanic seamounts dominate the park. 
Their gently sloping summits have accumulated veneers of sediment, which in places have formed fields of bedforms. 
Steep cliffs, debris and large mass movement scars encircle each seamount, and contrast with the lower gradient abyssal plains from which they rise. 
Spanning over 3 km of ocean depths, the seamounts are likely to serve multiple and important roles as breeding locations, resting areas, navigational landmarks or supplementary feeding grounds for some cetaceans (e.g. humpback whales, sperm whales). 
They may also act as important aggregation points for other highly migratory pelagic species. 
The bathymetry shown here was collected on two surveys - the first in 2007 by Geoscience Australia and the second in 2017 by Geoscience Australia in collaboration with the Japan Agency for Marine-Earth Science and Technology. 
The Gifford Marine Park has also been the focus of a study undertaken by the Marine Biodiversity Hub as part of the National Environmental Science Program.


Flythrough movie of Perth Canyon Marine Park, southwest Western Australia showing seafloor bathymetry and marine life that occurs within the park.
The park encompasses a diversity of geomorphic features, ranging from gently sloping soft sediment plains to near-vertical towering cliffs of exposed bedrock.
This geodiversity extends from the head of Perth Canyon at the shelf break to the slope-confined submarine canyons that dissect the lower continental slope.
Spanning almost 4.5 km of ocean depths, the Perth Canyon has a significant influence on the local ecosystem across the food chain.
The size and location of the canyon is such that it promotes upwelling from the deep ocean, leading to plankton blooms that attract seasonal aggregations of larger pelagic fish, including whales.
Over geological time, the canyon has evolved to provide extensive areas of potential seabed habitat suitable for deep-sea corals and sponges.
The Perth Canyon has been the focus of a study undertaken by the Marine Biodiversity Hub as part of the National Environmental Science Program.

Flythrough movie of Bremer Commonwealth Marine Reserve, southwest Western Australia showing bathymetry of Bremer Canyon, Hood Canyon, Henry Canyon and Knob Canyon.
These canyons are part of the Albany Group of 81 canyons that extend along the continental margin of southwest Australia reaching to water depths of 4000 m.
The Bremer Canyon is one of the few canyons in the group that have incised into the continental shelf, providing a pathway for upwelling of nutrient rich waters to the shelf.
This upwelling is thought to form the basis for aggregations of marine life around the Bremer and adjacent canyons, including orca whales and giant squid.
The Bremer offshore region has been the focus of a study undertaken in 2017 by the Marine Biodiversity Hub as part of the National Environmental Science Program.

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