Reef HQ

Reef HQ (typeset as ReefHQ) is the largest living coral reef aquarium. It is located in Townsville, Queensland, Australia. The aquarium was built as a Bicentennial Commemorative project and is a part of the Great Barrier Reef Marine Park Authority (GBRMPA). The Coral Reef Exhibit has 130 coral species and 120 fish species along with hundreds of species of sea stars, sea urchins, sea cucumbers, brittle stars, feather stars, snails, worms and sponges.

History

Reef HQ was originally the vision of Dr Graeme Kelleher, a former chairman of the Great Barrier Reef Marine Park Authority (GBRMPA). Dr Kelleher's primary objective was to bring the marine environment onto the land and make it easily accessible to the public whilst also encouraging the public to help protect the reef.

ReefHQ was originally known as Great Barrier Reef Aquarium when it opened on 14 June 1987. The aquarium was renamed "ReefHQ" in 1999. Since 2009 the name of the aquarium was changed to reflect its original name. It is now known as Reef HQ Great Barrier Reef Aquarium.

Reef

A reef is a bar of rock, sand, coral or similar material, lying beneath the surface of water. Reefs may be up to 261 feet (80 m) below the surface.

Many reefs result from abiotic processes—deposition of sand, wave erosion planing down rock outcrops, and other natural processes—but the best-known reefs are the coral reefs of tropical waters developed through biotic processes dominated by corals and calcareous algae. Artificial reefs such as shipwrecks are sometimes created to enhance physical complexity on generally featureless sand bottoms in order to attract a diverse assemblage of organisms, especially fish.

Biotic reef

There is a variety of biotic reef types, including oyster reefs, but the most massive and widely distributed are tropical coral reefs. Although corals are major contributors to the framework and bulk material comprising a coral reef, the organisms most responsible for reef growth against the constant assault from ocean waves are calcareous algae, especially, although not entirely, species of coralline algae.

Vein (geology)

In geology, a vein is a distinct sheetlike body of crystallized minerals within a rock. Veins form when mineral constituents carried by an aqueous solution within the rock mass are deposited through precipitation. The hydraulic flow involved is usually due to hydrothermal circulation.

Veins are classically thought of as being the result of growth of crystals on the walls of planar fractures in rocks, with the crystal growth occurring normal to the walls of the cavity, and the crystal protruding into open space. This certainly is the method for the formation of some veins. However, it is rare in geology for significant open space to remain open in large volumes of rock, especially several kilometers below the surface. Thus, there are two main mechanisms considered likely for the formation of veins: open-space filling and crack-seal growth.

Open space filling

Open space filling is the hallmark of epithermal vein systems, such as a stockwork, in greisens or in certain skarn environments. For open space filling to take effect, the confining pressure is generally considered to be below 0.5 GPa, or less than 3-5 kilometers. Veins formed in this way may exhibit a colloform, agate-like habit, of sequential selvages of minerals which radiate out from nucleation points on the vein walls and appear to fill up the available open space. Often evidence of fluid boiling is present. Vugs, cavities and geodes are all examples of open-space filling phenomena in hydrothermal systems.

Reef knot

The reef knot, or square knot, is an ancient and simple binding knot used to secure a rope or line around an object. It is sometimes also referred to as a Hercules knot. The knot is formed by tying a left-handed overhand knot and then a right-handed overhand knot, or vice versa. A common mnemonic for this procedure is "right over left; left over right", which is often appended with the rhyming suffix "... makes a knot both tidy and tight". Two consecutive overhands of the same handedness will make a granny knot. The working ends of the reef knot must emerge both at the top or both at the bottom, otherwise a thief knot results.

Although the reef knot is often seen used for tying two ropes together, it is not recommended for this purpose because of the potential instability of the knot, and over-use has resulted in many deaths (see #Misuse as a bend).

Naming

The reef knot is at least between 4,000 and 9,000 years old. The name "reef knot" dates from at least 1794 and originates from its common use to reef sails, that is to tie part of the sail down to decrease its effective surface area in strong winds. To release the knot a sailor could collapse it with a pull of one hand; the sail's weight would make the collapsed knot come apart. It is specifically this behavior which makes the knot unsafe for connecting two ropes together.