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61-644: Because the deep water carries abundant nutrients up from the ocean floor , the upwelling area differs from the rest of the Great Australian Bight, especially the areas offshore of Western Australia and the Nullarbor Plain in South Australia , which are generally nutrient-poor. Every summer, the upwelling sustains a bountiful ecosystem that attracts blue whales and supports rich fisheries . The Great South Australian Coastal Upwelling System (GSACUS)

122-638: A dispute between European whalers and the Gunditjmara people over ownership of a beached whale. Beginning in the mid-1840s, whaling and sealing were established as organized industries off the Bonney Coast. Today, southern rock lobster (referred to locally as crayfish) and trawling are the most important fishing industries in the Bonney Upwelling. whereas the upwelling off the Eyre Peninsula supports

183-496: A distance of approximately 800 kilometres (500 mi). While the Bonney Upwelling, where the strongest and most reliable upwelling events occur, was reported and explored over 30 years ago, the full extent of the upwelling system was discovered only as recently as 2004. The Bonney Upwelling is the largest and most predictable upwelling in the GSACUS. It stretches from Portland, Victoria to Robe, South Australia . The continental shelf

244-487: A globe-spanning mid-ocean ridge system, as well as undersea volcanoes , oceanic trenches , submarine canyons , oceanic plateaus and abyssal plains . The mass of the oceans is approximately 1.35 × 10   metric tons , or about 1/4400 of the total mass of the Earth. The oceans cover an area of 3.618 × 10  km with a mean depth of 3,682 m, resulting in an estimated volume of 1.332 × 10  km . Each region of

305-539: A large sardine fishery, operating chiefly out of Port Lincoln , South Australia. Next to the Great Barrier Reef , the GSACUS and its ecosystem can be regarded as one of Australia's natural wonders. Due to its importance as a blue whale feeding and aggregation site, in 2002 the Bonney Upwelling was listed as critical habitat "requiring effective protection from user impacts" under Australia's Environment Protection and Biodiversity Conservation Act 1999 . In addition to

366-501: A rate anywhere from 1 mm to 1 cm every 1000 years. Hydrogenous sediments are uncommon. They only occur with changes in oceanic conditions such as temperature and pressure. Rarer still are cosmogenous sediments. Hydrogenous sediments are formed from dissolved chemicals that precipitate from the ocean water, or along the mid-ocean ridges, they can form by metallic elements binding onto rocks that have water of more than 300 °C circulating around them. When these elements mix with

427-523: Is Australia 's only deep-reaching coastal upwelling system, with nutrient-enriched water stemming from depths exceeding 300 metres (980 ft). Recently, a new upwelling centre has been discovered on the western shelf of Tasmania. Since this new upwelling centre is located outside South Australian waters, the entire upwelling system should be rather called the Great Southern Australian Coastal Upwelling System . During

488-402: Is absorbed before it can reach deep ocean water, the energy source for deep benthic ecosystems is often organic matter from higher up in the water column that drifts down to the depths. This dead and decaying matter sustains the benthic food chain ; most organisms in the benthic zone are scavengers or detritivores . Seabed topography ( ocean topography or marine topography ) refers to

549-407: Is 631.6 mm (24.87 in), spread between 153.4 precipitation days. The town has 56.0 clear days and 163.3 cloudy days per annum. Extreme temperatures have ranged from 39.6 °C (103.3 °F) on 14 February 1981 to −2.6 °C (27.3 °F) on 19 July 1982. Climate data is also available for Robe Airport, located 4.6 kilometres (2.9 mi) SE of the town. The inland weather station has

610-434: Is a vertical coordinate used in geology, paleontology , oceanography , and petrology (see ocean drilling ). The acronym "mbsf" (meaning "meters below the seafloor") is a common convention used for depths below the seafloor. Sediments in the seabed vary in origin, from eroded land materials carried into the ocean by rivers or wind flow, waste and decompositions of sea creatures, and precipitation of chemicals within

671-477: Is abundant in the deep sea around hydrothermal vents . Large deep sea communities of marine life have been discovered around black and white smokers – vents emitting chemicals toxic to humans and most vertebrates . This marine life receives its energy both from the extreme temperature difference (typically a drop of 150 degrees) and from chemosynthesis by bacteria . Brine pools are another seabed feature, usually connected to cold seeps . In shallow areas,

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732-580: Is controversial. Environmental advocacy groups such as Greenpeace and the Deep Sea Mining Campaign claimed that seabed mining has the potential to damage deep sea ecosystems and spread pollution from heavy metal-laden plumes. Critics have called for moratoria or permanent bans. Opposition campaigns enlisted the support of some industry figures, including firms reliant on the target metals. Individual countries with significant deposits within their exclusive economic zones (EEZ's) are exploring

793-447: Is divided into layers or zones, each with typical features of salinity, pressure, temperature and marine life , according to their depth. Lying along the top of the abyssal plain is the abyssal zone , whose lower boundary lies at about 6,000 m (20,000 ft). The hadal zone – which includes the oceanic trenches, lies between 6,000 and 11,000 metres (20,000–36,000 ft) and is the deepest oceanic zone. Depth below seafloor

854-461: Is estimated that the global ocean floor holds more than 120 million tons of cobalt, five times the amount found in terrestrial reserves. As of July 2024 , only exploratory licenses have been issued, with no commercial-scale deep sea mining operations yet. The International Seabed Authority (ISA) regulates all mineral-related activities in international waters and has granted 31 exploration licenses so far: 19 for polymetallic nodules, mostly in

915-488: Is narrow offshore of the "Bonney Coast" - only about 20 kilometres (12 mi) from the shore to the continental slope - and deep water is funneled to the surface through a series of submarine canyons . Upwelling at Kangaroo Island and the Eyre Peninsula is different than at the Bonney Upwelling. Here, the continental shelf is generally much wider than at the Bonney Coast - up to 100 kilometres (62 mi) wide off

976-414: Is not moving so quickly. This means that larger grains of sediment may come together in higher energy conditions and smaller grains in lower energy conditions. Benthos (from Ancient Greek βένθος ( bénthos )  'the depths [of the sea]'), also known as benthon, is the community of organisms that live on, in, or near the bottom of a sea, river , lake , or stream , also known as

1037-480: Is the next most abundant material on the seafloor. Biogenous sediments are biologically produced by living creatures. Sediments made up of at least 30% biogenous material are called "oozes." There are two types of oozes: Calcareous oozes and Siliceous oozes. Plankton grow in ocean waters and create the materials that become oozes on the seabed. Calcareous oozes are predominantly composed of calcium shells found in phytoplankton such as coccolithophores and zooplankton like

1098-561: Is through their descriptive classification. These sediments vary in size, anywhere from 1/4096 of a mm to greater than 256 mm. The different types are: boulder, cobble, pebble, granule, sand, silt, and clay, each type becoming finer in grain. The grain size indicates the type of sediment and the environment in which it was created. Larger grains sink faster and can only be pushed by rapid flowing water (high energy environment) whereas small grains sink very slowly and can be suspended by slight water movement, accumulating in conditions where water

1159-468: The Wayback Machine to celebrate the abundance of the Bonney Upwelling, and to begin the summer fishing season. Humans have exploited the GSACUS for thousands of years. Oral histories of local Aboriginal tribes indicate a close connection to the ocean, and said tribes may possibly have eaten beached whales . The Convincing Ground massacre , which took place near Portland, Victoria in 1829, arose over

1220-437: The abyssal plain regions of the ocean are relatively flat and covered in many layers of sediments. Sediments in these flat areas come from various sources, including but not limited to: land erosion sediments from rivers, chemically precipitated sediments from hydrothermal vents, Microorganism activity, sea currents eroding the seabed and transporting sediments to the deeper ocean, and phytoplankton shell materials. Where

1281-453: The benthic zone . This community lives in or near marine or freshwater sedimentary environments , from tidal pools along the foreshore , out to the continental shelf , and then down to the abyssal depths . Many organisms adapted to deep-water pressure cannot survive in the upper parts of the water column . The pressure difference can be very significant (approximately one atmosphere for every 10 metres of water depth). Because light

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1342-402: The seafloor , sea floor , ocean floor , and ocean bottom ) is the bottom of the ocean . All floors of the ocean are known as 'seabeds'. The structure of the seabed of the global ocean is governed by plate tectonics . Most of the ocean is very deep, where the seabed is known as the abyssal plain . Seafloor spreading creates mid-ocean ridges along the center line of major ocean basins, where

1403-779: The CCZ; 7 for polymetallic sulphides in mid-ocean ridges ; and 5 for cobalt-rich crusts in the Western Pacific Ocean . There is a push for deep sea mining to commence by 2025, when regulations by the ISA are expected to be completed. Deep sea mining is also possible in the exclusive economic zone (EEZ) of countries, such as Norway , where it has been approved. In 2022, the Cook Islands Seabed Minerals Authority (SBMA) granted three exploration licenses for cobalt-rich polymetallic nodules within their EEZ. Papua New Guinea

1464-478: The Eyre Peninsula - and water is not drawn directly from the seafloor to the surface. Instead, field data and hydrodynamic modelling suggest that the upwelling follows from a chain of processes. This chain of processes starts in the deep submarine canyons of the Murray Canyon Group, located south of Kangaroo Island, where localized sub-surface upwelling brings a pool of cold water from the abyssal plains up to

1525-552: The Province of South Australia was established, as a seaport, administrative centre and township . Robe was named after the fourth Governor of South Australia , Major Frederick Robe , who chose the site as a port in 1845. The town was proclaimed as a port in 1847. It became South Australia's second-busiest international port, after Port Adelaide , in the 1850s. Robe's trade was drawn from a large hinterland that extended into western Victoria, and many roadside inns were built to cater for

1586-585: The Underwater Cultural Heritage . The convention aims at preventing looting and the destruction or loss of historic and cultural information by providing an international legal framework. Robe, South Australia Robe is a town and fishing port located in the Limestone Coast of South Australia . The town's distinctive combination of historical buildings, ocean, fishing fleets, lakes and dense bush attracts many tourists. Robe lies on

1647-438: The abundance of the GSACUS ecosystem can approach that of some of the world’s most productive upwelling centers, such as those offshore of Peru , California , and Namibia . During upwelling events, surface chlorophyll a concentrations, an indicator of phytoplankton abundance, increase tenfold. Phytoplankton blooms bring about swarms of krill , which in turn attract blue whales . Blue whales are found in various locations off

1708-536: The amount of plastic thought – per Jambeck et al., 2015 – to currently enter the oceans annually. Deep sea mining is the extraction of minerals from the seabed of the deep sea . The main ores of commercial interest are polymetallic nodules , which are found at depths of 4–6 km (2.5–3.7 mi) primarily on the abyssal plain . The Clarion–Clipperton zone (CCZ) alone contains over 21 billion metric tons of these nodules, with minerals such as copper , nickel , and cobalt making up 2.5% of their weight. It

1769-585: The area. An automatic lighthouse was built on higher ground in 1973. During the Victorian gold rushes about 1857, the Victorian government introduced a landing tax of £10 per person to deter Chinese immigrants – more than the cost of their voyage. To bypass the tax, more than 16,000 Chinese people landed at Robe to walk overland for 320 kilometres (200 miles) to the goldfields , mainly at Ballarat and Bendigo . Robe's importance decreased with

1830-422: The austral summer, high-pressure systems over the Great Australian Bight cause southeasterly winds to blow over the coasts of Victoria and South Australia. When winds blow parallel to the shoreline, Ekman transport pushes water to the left of the wind direction (in the southern hemisphere), which in this case is westward and offshore. To replace the water moving offshore, cold waters from the ocean floor rise to

1891-485: The balance between sedimentary processes and hydrodynamics however, anthropogenic influences can impact the natural system more than any physical driver. Marine topographies include coastal and oceanic landforms ranging from coastal estuaries and shorelines to continental shelves and coral reefs . Further out in the open ocean, they include underwater and deep sea features such as ocean rises and seamounts . The submerged surface has mountainous features, including

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1952-422: The blue whale, one species of shark is listed as critically endangered , and five bird and two whale species are listed as endangered . Significant reserves of natural gas are present beneath the Bonney Coast, and are undergoing exploration. Fears have been expressed that expanded gas drilling may threaten whales through noise pollution and ship collisions. Ocean floor The seabed (also known as

2013-556: The building of railways in the 19th century to Kingston and Beachport , about 40 kilometres (25 miles) respectively to its north and south. It continues as a service centre for the surrounding rural areas and home to a fishing fleet: especially important in the local economy is the rocklobster fishery. AFL footballer Jordan Dawson who currently plays for and captain of the Adelaide Crows Football Club also came from Robe. Robe has many heritage-listed places, including

2074-536: The bullock teamsters bringing down the wool, including the Bush Inn still standing on the outskirts of Robe. Exports included horses, sheep skins and wool. The Customs House has been listed on the South Australian Heritage Register since 1980. A stone obelisk was built on Cape Dombey in 1852 to help ships navigate safely into the bay. Even so, there have been a number of shipwrecks along the coast in

2135-450: The cold sea water they precipitate from the cooling water. Known as manganese nodules , they are composed of layers of different metals like manganese, iron, nickel, cobalt, and copper, and they are always found on the surface of the ocean floor. Cosmogenous sediments are the remains of space debris such as comets and asteroids, made up of silicates and various metals that have impacted the Earth. Another way that sediments are described

2196-543: The continental shelf. This dense-water pool, named the Kangaroo Island Pool , drifts along the shelf bottom just offshore of Kangaroo Island and the Eyre Peninsula. When a classical wind-driven upwelling event occurs, normally two to three times a summer, cold water is upwelled from the pool, not directly from the ocean floor . Extensive upwelling of nutrient-rich water makes the GSACUS an important marine hot spot on Australia's southern shelves. During upwelling events,

2257-465: The continental slope and the abyssal plain usually has a more gradual descent, and is called the continental rise , which is caused by sediment cascading down the continental slope. The mid-ocean ridge , as its name implies, is a mountainous rise through the middle of all the oceans, between the continents. Typically a rift runs along the edge of this ridge. Along tectonic plate edges there are typically oceanic trenches – deep valleys, created by

2318-597: The deepest waters are collectively known, as a habitat for creatures, as the " benthos ". Most of the seabed throughout the world's oceans is covered in layers of marine sediments . Categorized by where the materials come from or composition, these sediments are classified as either: from land ( terrigenous ), from biological organisms (biogenous), from chemical reactions (hydrogenous), and from space (cosmogenous). Categorized by size, these sediments range from very small particles called clays and silts , known as mud, to larger particles from sand to boulders . Features of

2379-495: The eastern Great Australian Bight during the upwelling season and feed on sardines ( Sardinops sagax ) and anchovies ( Engraulis australis ). Furthermore, the many dead organisms that fall to the continental shelf support populations of southern rock lobster and giant crab . The GSACUS supports a productive fishery, and local fishers recognize the bounty that the upwelling provides them. Every November, Portland, Victoria , hosts an Upwelling Festival Archived 2013-05-23 at

2440-551: The following: Robe has a warm-summer mediterranean climate ( Köppen: Csb), with tepid, dry summers and mild, drizzly winters. Average maxima vary from 22.6 °C (72.7 °F) in February to 13.6 °C (56.5 °F) in July and average minima fluctuate between 13.7 °C (56.7 °F) in January and February and 8.2 °C (46.8 °F) in July. The mean average annual precipitation

2501-416: The foraminiferans. These calcareous oozes are never found deeper than about 4,000 to 5,000 meters because at further depths the calcium dissolves. Similarly, Siliceous oozes are dominated by the siliceous shells of phytoplankton like diatoms and zooplankton such as radiolarians. Depending on the productivity of these planktonic organisms, the shell material that collects when these organisms die may build up at

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2562-444: The mantle circulation movement from the mid-ocean mountain ridge to the oceanic trench. Hotspot volcanic island ridges are created by volcanic activity, erupting periodically, as the tectonic plates pass over a hotspot. In areas with volcanic activity and in the oceanic trenches there are hydrothermal vents – releasing high pressure and extremely hot water and chemicals into the typically freezing water around it. Deep ocean water

2623-448: The oceans have a common structure, created by common physical phenomena, mainly from tectonic movement, and sediment from various sources. The structure of the oceans, starting with the continents, begins usually with a continental shelf , continues to the continental slope – which is a steep descent into the ocean, until reaching the abyssal plain – a topographic plain , the beginning of the seabed, and its main area. The border between

2684-451: The rest of the GSACUS, but incomplete whale surveys are insufficient to establish their true range. Other marine life that thrives in the upwelling includes filter feeders like sponges , bryozoans , and corals . These animals feed predators such as seabirds, fishes, Australian fur seals , and penguins . The upwelling plays also an important role in the life cycle of juvenile southern bluefin tuna ( Thunnus maccoyii ), which accumulate in

2745-537: The sea water itself, including some from outer space. There are four basic types of sediment of the sea floor: Terrigenous sediment is the most abundant sediment found on the seafloor. Terrigenous sediments come from the continents. These materials are eroded from continents and transported by wind and water to the ocean. Fluvial sediments are transported from land by rivers and glaciers, such as clay, silt, mud, and glacial flour. Aeolian sediments are transported by wind, such as dust and volcanic ash. Biogenous sediment

2806-482: The seabed , and these satellite-derived maps are used extensively in the study and exploration of the ocean floor. In 2020 scientists created what may be the first scientific estimate of how much microplastic currently resides in Earth's seafloor , after investigating six areas of ~3 km depth ~300 km off the Australian coast. They found the highly variable microplastic counts to be proportionate to plastic on

2867-468: The seabed are governed by the physics of sediment transport and by the biology of the creatures living in the seabed and in the ocean waters above. Physically, seabed sediments often come from the erosion of material on land and from other rarer sources, such as volcanic ash . Sea currents transport sediments, especially in shallow waters where tidal energy and wave energy cause resuspension of seabed sediments. Biologically, microorganisms living within

2928-440: The seabed can host sediments created by marine life such as corals, fish, algae, crabs, marine plants and other organisms. The seabed has been explored by submersibles such as Alvin and, to some extent, scuba divers with special equipment. Hydrothermal vents were discovered in 1977 by researchers using an underwater camera platform. In recent years satellite measurements of ocean surface topography show very clear maps of

2989-404: The seabed has typical features such as common sediment composition, typical topography, salinity of water layers above it, marine life, magnetic direction of rocks, and sedimentation . Some features of the seabed include flat abyssal plains , mid-ocean ridges , deep trenches , and hydrothermal vents . Seabed topography is flat where layers of sediments cover the tectonic features. For example,

3050-400: The seabed is slightly shallower than the surrounding abyssal plain. From the abyssal plain, the seabed slopes upward toward the continents and becomes, in order from deep to shallow, the continental rise , slope , and shelf . The depth within the seabed itself, such as the depth down through a sediment core , is known as the "depth below seafloor". The ecological environment of the seabed and

3111-501: The seabed sediments change seabed chemistry. Marine organisms create sediments, both within the seabed and in the water above. For example, phytoplankton with silicate or calcium carbonate shells grow in abundance in the upper ocean, and when they die, their shells sink to the seafloor to become seabed sediments. Human impacts on the seabed are diverse. Examples of human effects on the seabed include exploration, plastic pollution, and exploitation by mining and dredging operations. To map

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3172-592: The seabed, ships use acoustic technology to map water depths throughout the world. Submersible vehicles help researchers study unique seabed ecosystems such as hydrothermal vents . Plastic pollution is a global phenomenon, and because the ocean is the ultimate destination for global waterways, much of the world's plastic ends up in the ocean and some sinks to the seabed. Exploitation of the seabed involves extracting valuable minerals from sulfide deposits via deep sea mining, as well as dredging sand from shallow environments for construction and beach nourishment . Most of

3233-411: The seafloor is actively spreading and sedimentation is relatively light, such as in the northern and eastern Atlantic Ocean , the original tectonic activity can be clearly seen as straight line "cracks" or "vents" thousands of kilometers long. These underwater mountain ranges are known as mid-ocean ridges . Other seabed environments include hydrothermal vents, cold seeps, and shallow areas. Marine life

3294-410: The shape of the land ( topography ) when it interfaces with the ocean. These shapes are obvious along coastlines, but they occur also in significant ways underwater. The effectiveness of marine habitats is partially defined by these shapes, including the way they interact with and shape ocean currents , and the way sunlight diminishes when these landforms occupy increasing depths. Tidal networks depend on

3355-501: The southeast coast of Australia, but most predominantly in the Bonney Upwelling region, which is one of 12 identified blue whale feeding sites worldwide. Marine biologist Peter Gill estimates that 100 blue whales visit the Bonney Upwelling area every year, ranging over 18,000 square kilometres (6,900 sq mi) of ocean from Robe, South Australia to Cape Otway in Victoria . The feeding grounds may extend further northwest, encompassing

3416-602: The southern shore of Guichen Bay , just off the Princes Highway . At the 2021 census , Robe had a population of 1252. Robe is the main town in the District Council of Robe local government area . It is in the state electorate of MacKillop and the federal Division of Barker . Robe is situated on the ancestral lands of the Buandig and Ngarrindjeri people. Europeans founded the town of Robe in 1846, ten years after

3477-519: The subject. Some children's play songs include elements such as "There's a hole at the bottom of the sea", or "A sailor went to sea... but all that he could see was the bottom of the deep blue sea". On and under the seabed are archaeological sites of historic interest, such as shipwrecks and sunken towns. This underwater cultural heritage is protected by the UNESCO Convention on the Protection of

3538-412: The surface and the angle of the seafloor slope. By averaging the microplastic mass per cm , they estimated that Earth's seafloor contains ~14 million tons of microplastic – about double the amount they estimated based on data from earlier studies – despite calling both estimates "conservative" as coastal areas are known to contain much more microplastic pollution . These estimates are about one to two times

3599-483: The surface. During upwelling events, local sea surface temperature drops by 2-3 degrees Celsius. Key upwelling centres form in three different locations, described in the sub-sections below; the Kangaroo Island and Eyre Peninsula centres are linked by the same upwelling process. Upwelling events occur nearly simultaneously across the three separate centres, appearing within a few days of each other, despite spanning

3660-403: The water column. Related technologies include robotic mining machines, as surface ships, and offshore and onshore metal refineries. Wind farms, solar energy, electric vehicles , and battery technologies use many of the deep-sea metals. Electric vehicle batteries are the main driver of the critical metals demand that incentivizes deep sea mining. The environmental impact of deep sea mining

3721-511: Was the first country to approve a deep sea mining permit for the Solwara 1 project, despite three independent reviews highlighting significant gaps and flaws in the environmental impact statement. The most common commercial model of deep sea mining proposed involves a caterpillar-track hydraulic collector and a riser lift system bringing the harvested ore to a production support vessel with dynamic positioning , and then depositing extra discharge down

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