Royston Island (also known as North Island) is an

island An island (or isle) is an isolated piece of habitat that is surrounded by a dramatically different habitat, such as water. Very small islands such as emergent land features on atolls can be called islets, skerries, cays or keys. An island ...

in the Australian state of

South Australia South Australia (commonly abbreviated as SA) is a state in the southern central part of Australia. It covers some of the most arid parts of the country. With a total land area of , it is the fourth-largest of Australia's states and territories ...

at the northern end of Pondalowie Bay on the south-west extremity of

Yorke Peninsula The Yorke Peninsula is a peninsula located northwest and west of Adelaide in South Australia, between Spencer Gulf on the west and Gulf St Vincent on the east. The peninsula is separated from Kangaroo Island to the south by Investigator Str ...

about north-west of the town of Stenhouse Bay. The island has enjoyed protected area status since 1967 and since 1972, it has been part of the Innes National Park.

Description

Royston Island is an island located on the

about north-west of the town of Stenhouse Bay at the northern end of Pondalowie Bay within about of Royston Head.DMH, 1985, charts 22 & 23 The island is fringed with detritus consisting of eroded

calcarenite Calcarenite is a type of limestone that is composed predominantly, more than 50 percent, of detrital (transported) sand-size (0.0625 to 2 mm in diameter), carbonate grains. The grains consist of sand-size grains of either corals, shells, ooi ...

and

granite Granite () is a coarse-grained ( phaneritic) intrusive igneous rock composed mostly of quartz, alkali feldspar, and plagioclase. It forms from magma with a high content of silica and alkali metal oxides that slowly cools and solidifies under ...

boulders which a talus slope rises to a “relatively flat, plateau-like summit” at a height of above sea level. The island is connected to Royston Head by a “shallow, partially drying reef.” Access to the island is reported as being “probably most accessible by small boat via the north-eastern coast.”

Formation, geology and oceanography

Royston Island was formed about 7000 years ago following the rise of sea levels at the start of the

Holocene The Holocene ( ) is the current geological epoch. It began approximately 11,650 cal years Before Present (), after the Last Glacial Period, which concluded with the Holocene glacial retreat. The Holocene and the preceding Pleistocene togeth ...

. Royston Island consists of a calcarenite upper layer over a “pronounced ridge of Lincoln Complex granite.” Royston Island is fringed partly on its north-west and south-east ends by fringing reefs while the waters surrounding its extent drop to a depth of within a distance of on its westside.

Flora and fauna

Flora

A survey carried out during 1982 on Royston Island recorded a total of nineteen plant species. The island's summit is dominated by a “low, windswept shrubland” consisting of

marsh saltbush ''Atriplex paludosa'', commonly known as marsh saltbush, is a species of saltbush endemic to Australia. Description It grows as an erect shrub up to a metre high. Leaves are oval in shape, one to four centimetres long, and 2 to 15 millimetres wi ...

and coast daisy-bush accompanied by less abundant species such as

southern sea-heath ''Frankenia pauciflora'', the common sea-heath or southern sea-heath, is an evergreen shrub native to southern Australia. It is part of the Frankenia genus of the Frankeniaceae family. It can be prostrate or may grow up to 0.5 m in height. Pi ...

, round-leaved pigface and pointed twinleaf. The talus slopes support shrubs of nitre-bush, native juniper, cockies tongue, African boxthorn, yellow-flowering sticky goodenia, Austral stork's bill, coastal lignum and

ruby saltbush ''Enchylaena tomentosa'', commonly known as barrier saltbush or ruby saltbush, is a small native shrub of Australia. Description ''Enchylaena tomentosa'' grows as a small perennial shrub, up to a meter in diameter. Leaves are slender and cylindr ...

, while calcrete ledges associated with the island's upper levels are “festooned with climbing

bower spinach ''Tetragonia implexicoma'', commonly known as bower spinach, is a species of plant in the Aizoaceae, or ice-plant family (biology), family. A similar species is ''Tetragonia tetragonioides'', however this species has larger leaves and a shorter f ...

.”

Fauna

Vertebrate animals are represented by birds and reptiles. As of 1982, little penguins were observed as being the common bird on the island followed by

silver gull The silver gull (''Chroicocephalus novaehollandiae'') is the most common gull of Australia. It has been found throughout the continent, but particularly at or near coastal areas. It is smaller than the Pacific gull (''Larus pacificus''), which ...

s. Both bird species used the island as a breeding colony. As of 2011, the status of the little penguin colony was not known. Also in 1982, the island is reported as supporting a “large population of marbled geckos.”

History

European discovery and use

Royston Island is reported as being named after Lord Royston, eldest son of Lord Hardwicke by Matthew Flinders in 1802. The island is also known as “North Island”.

Protected areas status

Royston Island first received protected area status along with Middle Island in Pondalowie Bay as a fauna conservation reserve declared under the ''Crown Lands Act 1929-1966'' on 16 March 1967. Since 1972, it has been part of the Innes National Park. Since 2012, the waters adjoining the shoreline of Royston Island have been within a habitat protection zone in the South Spencer Gulf Marine Park.DEWNR, 2012, page 24 Since at least 2014, Royston Island and the other two islands in Pondalowie Bay (from north to south), Middle Island and South South Island, are closed to access by visitors to the national park.DEWNR, 2014 Penguin breeding sites were noted there in a 1996 survey of South Australia's offshore islands.

Citations and references

Citations

References

* * * * * * {{DEFAULTSORT:Royston Island Islands of South Australia Uninhabited islands of Australia Spencer Gulf Yorke Peninsula Penguin colonies