Flinders Reef or Flinders Reefs is an isolated oceanic

coral reef A coral reef is an underwater ecosystem characterized by reef-building corals. Reefs are formed of colonies of coral polyps held together by calcium carbonate. Most coral reefs are built from stony corals, whose polyps cluster in groups. Co ...

in the

Coral Sea The Coral Sea () is a marginal sea of the South Pacific off the northeast coast of Australia, and classified as an interim Australian bioregion. The Coral Sea extends down the Australian northeast coast. Most of it is protected by the Fre ...

of the western

Pacific Ocean The Pacific Ocean is the largest and deepest of Earth's five oceanic divisions. It extends from the Arctic Ocean in the north to the Southern Ocean (or, depending on definition, to Antarctica) in the south, and is bounded by the continen ...

. It lies east of

Australia Australia, officially the Commonwealth of Australia, is a Sovereign state, sovereign country comprising the mainland of the Australia (continent), Australian continent, the island of Tasmania, and numerous List of islands of Australia, sma ...

and the extensive

Great Barrier Reef The Great Barrier Reef is the world's largest coral reef system composed of over 2,900 individual reefs and 900 islands stretching for over over an area of approximately . The reef is located in the Coral Sea, off the coast of Queensland, ...

. Due to its remote location, it remains poorly studied. However, this isolation has also made it a potential site to

mark Mark may refer to: Currency * Bosnia and Herzegovina convertible mark, the currency of Bosnia and Herzegovina * East German mark, the currency of the German Democratic Republic * Estonian mark, the currency of Estonia between 1918 and 1927 * Fi ...

the beginning of the

Anthropocene The Anthropocene ( ) is a proposed geological epoch dating from the commencement of significant human impact on Earth's geology and ecosystems, including, but not limited to, anthropogenic climate change. , neither the International Commissi ...

Location

Flinders Reef is one of a number of oceanic reefs rising from the Queensland plateau. It lies near the southwest edge, with the Queensland trough to the west separating it from the

, and the Townsville trough to the south separating it from the Marion plateau. It is from the Great Barrier Reef, and northeast of the Australian coastline. The position of the reef is around 17°37'S, 148°31'E, with weather station

Cay A cay ( ), also spelled caye or key, is a small, low-elevation, sandy island on the surface of a coral reef. Cays occur in tropical environments throughout the Pacific, Atlantic, and Indian Oceans, including in the Caribbean and on the Great ...

located at 17°44'S, 148°26'E. This area falls within the

, which has a

tropical climate Tropical climate is the first of the five major climate groups in the Köppen climate classification identified with the letter A. Tropical climates are defined by a monthly average temperature of 18 °C (64.4 °F) or higher in the cool ...

and high rainfall. Water currents around the reef tend to originate from the southeast, propelled by

trade wind The trade winds or easterlies are the permanent east-to-west prevailing winds that flow in the Earth's equatorial region. The trade winds blow mainly from the northeast in the Northern Hemisphere and from the southeast in the Southern Hemisph ...

s. These currents form part of the wider

South Equatorial Current The South Equatorial Current are ocean currents in the Pacific, Atlantic, and Indian Ocean that flow east-to-west between the equator and about 20 degrees south. In the Pacific and Atlantic Oceans, it extends across the equator to about 5 degr ...

. This drives changes in pH in the reef water, while annual pH changes are affected by

La Niña La Niña (; ) is an oceanic and atmospheric phenomenon that is the colder counterpart of as part of the broader El Niño–Southern Oscillation (ENSO) climate pattern. The name ''La Niña'' originates from Spanish for "the girl", by an ...

events. The prevailing wind is mostly westward, coming from 270°. The region sometimes sees

cyclone In meteorology, a cyclone () is a large air mass that rotates around a strong center of low atmospheric pressure, counterclockwise in the Northern Hemisphere and clockwise in the Southern Hemisphere as viewed from above (opposite to an anti ...

Structure

The reef is quite large compared to its neighbours, stretching north to south. A continuous reef barrier stretches down the Eastern edge. Rising up from water over deep, most of the reef lies at a depth of just . Sand covers 25 per cent of the

reef flat A fringing reef is one of the three main types of coral reef. It is distinguished from the other main types, barrier reefs and atolls, in that it has either an entirely shallow backreef zone (lagoon) or none at all. If a fringing reef grows direc ...

s. The main body is sometimes referred to as North Flinders Reef, with South Flinders Reef being a smaller reef lying directly south of the main area. Dart Reef and Heralds Surprise are small reefs lying to the northwest and northeast respectively of the main reef.

Biodiversity

The remote location means Flinders Reef and nearby reefs are poorly studied. The wildlife is distinct from that of the Great Barrier Reef, with these reefs likely acting as conduits for species dispersal between the Great Barrier Reef and the wider western

. The reef is part of the

Coral Sea Marine Park The Coral Sea Marine Park (previously known as the Coral Sea Commonwealth Marine Reserve) is an Australian marine park located in the Coral Sea off the coast of Queensland. The marine park covers an area of and is assigned IUCN category IV. ...

, and is designated as an IUCN protected habitat or species management area. One threat to the reef is

climate change In common usage, climate change describes global warming—the ongoing increase in global average temperature—and its effects on Earth's climate system. Climate change in a broader sense also includes previous long-term changes to E ...

, which has caused

coral bleaching Coral bleaching is the process when corals become white due to various stressors, such as changes in temperature, light, or nutrients. Bleaching occurs when coral polyps expel the zooxanthellae (dinoflagellates that are commonly referred to as alg ...

. The area is a

recreational diving Recreational diving or sport diving is diving for the purpose of leisure and enjoyment, usually when using scuba equipment. The term "recreational diving" may also be used in contradistinction to "technical diving", a more demanding aspect of r ...

site. The reef flat areas of Flinders Reef have large populations of

sponge Sponges, the members of the phylum Porifera (; meaning 'pore bearer'), are a basal animal clade as a sister of the diploblasts. They are multicellular organisms that have bodies full of pores and channels allowing water to circulate through t ...

s, mostly consisting of four similar

Dictyoceratida Dictyoceratida is an order of sponges in the subclass Ceractinomorpha containing five families. Along with the Dendroceratida, it is one of the two orders of demosponges that make up the keratose or "horny" sponges, in which a mineral skeleton is ...

species: one from the

Thorectidae Thorectidae is a family of sea sponges in the order Dictyoceratida Dictyoceratida is an order of sponges in the subclass Ceractinomorpha containing five families. Along with the Dendroceratida, it is one of the two orders of demosponges that m ...

family, and one each of the genera ''

Carteriospongia ''Carteriospongia'' is a genus of sea sponges in the family Thorectidae. There is some debate around the taxonomy of the group, with a 2021 molecular and morphological assessment of the subfamily Phyllospongiinae suggesting that ''Carteriospong ...

'', '' Phyllospongia'', and ''

''. A fifth species, part of the '' Dictyonella'' genus, is much rarer. Concentrations of sponges can reach per , and they cover around 7.3 per cent of the reef flat. At least one of these species may be

phototropic Phototropism is the growth of an organism in response to a light stimulus. Phototropism is most often observed in plants, but can also occur in other organisms such as fungi. The cells on the plant that are farthest from the light contain a hor ...

, and through partnership with symbiotic

cyanobacteria Cyanobacteria (), also known as Cyanophyta, are a phylum of gram-negative bacteria that obtain energy via photosynthesis. The name ''cyanobacteria'' refers to their color (), which similarly forms the basis of cyanobacteria's common name, blu ...

these sponges may extract over 50 per cent of their nutrition from sunlight.

Anthropocene marker

Due to its isolation from local human influence, Flinders Reef is a candidate for the location of a

Global Boundary Stratotype Section and Point A Global Boundary Stratotype Section and Point (GSSP) is an internationally agreed upon reference point on a stratigraphic section which defines the lower boundary of a stage on the geologic time scale. The effort to define GSSPs is conducted b ...

to mark the beginning of the

. The transition to the Anthropocene can be seen in samples of ''

Porites ''Porites'' is a genus of stony coral; they are small polyp stony (SPS) corals. They are characterised by a finger-like morphology. Members of this genus have widely spaced calices, a well-developed wall reticulum and are bilaterally symmetric ...

'' coral, which can live for hundreds of years and continue growing throughout this period. Cores taken from this coral have annual growth bands between and long. These annual bands preserve information about the water chemistry of the reef at the time they formed. Two cores have currently been taken. One, collected in May 1992 at depth, is long and extends from 1708 to 1992. The second one was taken in December 2017 at a depth of , and its covers the period from 1835 to 2017. Both cores show a rise of carbon-14 in the 1950s, related to the use of

nuclear weapon A nuclear weapon is an explosive device that derives its destructive force from nuclear reactions, either fission (fission bomb) or a combination of fission and fusion reactions ( thermonuclear bomb), producing a nuclear explosion. Both bom ...

s, which declines after 1975. They also preserve changes in carbon isotopes which are caused by the burning of

fossil fuel A fossil fuel is a hydrocarbon-containing material formed naturally in the Earth's crust from the remains of dead plants and animals that is extracted and burned as a fuel. The main fossil fuels are coal, oil, and natural gas. Fossil fuels m ...

s. Through changes in

oxygen Oxygen is the chemical element with the symbol O and atomic number 8. It is a member of the chalcogen group in the periodic table, a highly reactive nonmetal, and an oxidizing agent that readily forms oxides with most elements as wel ...

strontium Strontium is the chemical element with the symbol Sr and atomic number 38. An alkaline earth metal, strontium is a soft silver-white yellowish metallic element that is highly chemically reactive. The metal forms a dark oxide layer when it is ex ...

, and

calcium Calcium is a chemical element with the symbol Ca and atomic number 20. As an alkaline earth metal, calcium is a reactive metal that forms a dark oxide-nitride layer when exposed to air. Its physical and chemical properties are most similar to ...

isotopes, information can be gained about surrounding ocean temperature, which began increasing in the 1850s, with this increase accelerating beginning in the 1970s.

Boron Boron is a chemical element with the symbol B and atomic number 5. In its crystalline form it is a brittle, dark, lustrous metalloid; in its amorphous form it is a brown powder. As the lightest element of the ''boron group'' it has th ...

isotopes indicate ocean acidity peaking in 2000. The environmental indicators in the cores from Flinders Reef correlate with cores taken from multiple locations within the Great Barrier Reef.

References

External links

3D map of Flinders Reefs
{{coord, -17.619, 148.464, format=dms, type:mountain_region:XP, display=title Coral Sea Islands Landforms of the Coral Sea Reefs of Australia