The Whitsundays Islands
Queensland – Australia
The Whitsundays Islands
The Whitsundays are a group of 74 islands situated on the coast of the Queensland in Australia and are part of the Great Barrier Reef World Heritage Area. There are 6 national parks among which there is Whitsundays Islands National Park where there is the famous Whitheaven beach, the most photographied-beach.
The Whitsundays’ name is coming from the British James Cook who discovered those islands, a day of Pentecost.
Those islands have been the home of Ngaro’s tribute that was aboriginal people of this area who have lived for at least 9000 years. Their occupation has been revealed due to stones axes and cutting tools found on South Molle Island.
Originally, those islands were a volcanic mountain range links to continent where volcanic activity continued for 37 million years. Those islands are continental’s islands that were part of the continent of Australia and the Whitsundays we see today were part of a mainland mountain range that were separated from the mainland a number of times due to ices ages, sea levels (low and high tides) over millions of years. But 10’000 years ago, at the end of the last ice age, the most recent change happened due to glaciers melting. Indeed, with this reason Coral Sea rose over the costal plain and left only mountain-tops and the rock ridges that we see today on Whitsundays.
Being on the same latitude as Tahiti in the northern hemisphere and Mauritius or Rio de Janeiro in the southern hemisphere, the archipelago of Whitsundays has a tropical climate. The temperature’s average is around 27.4C° and may rise until 30 degrees while summer temperatures from December to February. As many of tropic islands, the Whitsundays have a form of brief tropical showers. The maximum temperatures in winter from June to August are around 24-25 degrees.
Among plants of Whitsundays islands, Coastal she-oak, hoop pines, eucalyptus, grasstrees, mangroves, native hibiscus, orchids, and seagrasses can be found. Soils, exposition to elements and avaibility of fresh water are the main factors for their growing.
Clade > Angiosperms
Family > Myrtaceae
Genus > Eucalyptus
They are found on Withsundays islands is from Myrtaceae family and is from Australia so are indigenous of Australian continent. Eucalyptus plants dominate 95% of forests. Most of species like E.globulus have been added in Europe on Mediterranean coastlines, also planted in Northern Africa (Morocco, Algeria, Tunisia, and Libya). On Madagascar Island they can be also found, in Mayotte, Reunion Island, and Southern Africa and many more other places in the world.
Eucalyptus may measure between 10 to 30 metres, and up to 90 metres in their adult size. Most of eucalyptus species have persistent leaves but few species lose them in the end of dry season.
Eucalyptus leaves are covered with oil glands, which gives essential oil. On a mature eucalyptus leaves are mainly lanceolate, petiolate, and alternate.
How recognize eucalyptus specie? By its flowers and fruits. Flowers have numerous and different colourful stamens, which can be cream, white, yellow, pink or red and are enclosed in a cap known as operculum. However, flowers have no petals.
Bark is very useful in order to recognize species because it can have many differences with its appearance such as a fibrous, hard, or smooth bark. Barks can also have incredible function like with E.globulus specie. Indeed, bark cells are able to do photosynthesis while there is no foliage.
Clade > Liliopsida
Family > Xanthorrhoea
Grasstree is a common name for Xanthorrhoeaspecies, which is coming from Australia. This plant is a monocot, which means they only have one cotyledon. They are growing on nutrient-poor soils and some of species are very slow growing. They may reach 6 metres tall with a growing about 0.8 cm to 6cm per year. Grasse tree leaves are narrow, linear and stiff and form a « skirt » around the base of the trunk. Time indication of the last fire is seen due to the lenght of the skirt. Indeed, the longer the skirt is the longer the duration without fire is. Certain grass trees regenerate after a bushfire by producing a large numbers of flowers but may take many years to flower and, however, not all species of grass trees are fire-tolerant.
Undersoil there is an impressive root system where mycorrhiza (als called fungus) surrounded the roots in a symbiotic relationship that helps the plant take up nutrients.
Grass trees are found on the east and west coast in Australia. This is an enderanged specie especially the Shinny Grass Tree that is about to be assessed by the IUCN Red List of Threathened Species with the Sand Grass Tree that is considered vulnereable to exctinction. Many species of grass tree have been devastated by cinnamon fungus.
Family > Zosteraceae
This plant is part of a groupe of plants called monocotyledons and is living under the water and their roots and rhizomes sink into the sediment of the seafloor for absorbing nutrients. Seagrasses has 72 species and can be named like eelgrass, turtle grass, tape grass, shoal grass, and spoon grass reflecting their role in marine ecosystems. They are growing in salty waters with high light for photosynthesis and in a depth of 1 to 3 meters. Antartica is the only continent where there is no seagrasses in its waters.
This plant grows both vertically and horizontally to capture sunlight and nutrients from the water and sediments. Asexual clonal growth and sexual reproduction are two methods used by this plant. Indeed, asexual clonal growth is necessary for enlarge a network in order it to spread into sediments and create new shoots. This is the horizonal growth and for the other one (vertical growth) this is the sexual reproduction, which is the same as terrestrial grasses but pollinisation is helped by water. How does it work ? Male seagrasses release pollens from stamens into the water then stamens move thanks to currents and when they meet a female flower there is pollinisation of pistil and fertilization takes place. There exists self-pollinisation but with this pollinisation genetic variation may be reduce.
Seagrasses have a particularity, which is modify their environment by creating new habitats that have important effects on others animals. It takes an important role in commercial fisheries and biodiversity by cleaning surrounding water and helping take carbon dioxide out of the atmosphere. Indeed, one square meter of seagrass can generate 10L of oxygen every day thanks to photosynthesis. Seagrasses leaves absorb nutrients, capture dirt and cut particles. In some poor regions, seagrass plants help nutrients by taking up from the soil and releasing them into the water thanks to their leaves.
Seagrasses are also nursery habitats because they provide shelter for inverterbrates (shrimps, crabs), small fishes and other species of fishes. Furthermore, they are important feeding grounds for many species around the world like green turtles, manatees, dugongs, and geese.
Seagrasses are vulnerable to physical disturbances such as waves and storms. Furthermore, some animals are destroying the rhizomes and the roots of this plant while they are searching for food. The human activities are part of the losses of this seagrass bed such as fertilizers and pollution blocking sunlight, which is necessary for their growth. Dredging is also a cause of their loss because of the lack of light and an increase of sediments in the water. Boat anchors and propellers are another factor of this loss fragmenting the habitat because it may increase erosion. Disease, temperatue, removal of fish, and invasive seaweed may devastate seagrasses as well.
Birds are the main animals living on the Whitsundays Islands but others species are part of this ecosystem such as wallabies, kangaroos, black flying-foxes, turtles and whales. In the insect’s world there are ants and spiders.
We will meet those incredible animals in another posts with more details and issues concerning them.
Lanceolate: Leaves are long, wider in the middle, shaped like a lance tip.
Petiolate: This ia a leaf with a petiole.
Petiole: This is a piece that attaches the leaf to the stem.
Monocotyledon: Plants with a single cotyledon.
Cotyledon: This is the embryo whitin the seed of a plant to give a primary leaf
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I travelled in: November 2012
Where: Airlie Beach – Queensland
© 2018 – Wairua Kaieke
Travel blogger and photographer from Switzerland.
I travel the world and with my photographs I show the beauty of the world in order to raise awareness to people about Planet Earth’s issues, and wildlife.