What type of environment does a dugong live in?
Dugongs occur in tropical and subtropical waters around the world.
Dugongs occur in tropical and subtropical waters around the world. Dugongs travel long distances meaning Australia shares populations with other neighbouring countries. In Australia, Dugongs swim in the warm shallow coastal waters of Northern Australia from the Moreton bay in the East to Shark bay on the Western Australian coast, these shallow waters protect the dugongs from large waves and storms. These areas contain large quantities of seagrass beds, the primary food source of dugongs. Some dugongs can be sighted in water up to 10m deep in several areas including the Torres Strait, Northern Great Barrier Reef region and Hervey Bay in SouthEast Queensland where the water is wide, shallow and protected.
Dugongs are not found within waters containing a mean temperature of less than 19 degrees celsius. This is as a result of the production of sea grass, their main food source.
Seagrass is usually controlled at its deepest edge by the availability of light for photosynthesis. Exposure at low tide, wave action and associated turbidity and low salinity from fresh water inflow determine seagrass species survival at the shallow edge. Seagrass survive in sites sheltered from wave action or where there is entrapment of water at low tide protecting the seagrasses from exposure to heat at low tide.
Rainfall does not impact amongst the dugong's environment, but this factor affects the survival of this organism as excessive amounts of rainfall can potentially 'drown' the seagrass, eliminating a major food source for the dugong.
Dugongs occur in tropical and subtropical waters around the world. Dugongs travel long distances meaning Australia shares populations with other neighbouring countries. In Australia, Dugongs swim in the warm shallow coastal waters of Northern Australia from the Moreton bay in the East to Shark bay on the Western Australian coast, these shallow waters protect the dugongs from large waves and storms. These areas contain large quantities of seagrass beds, the primary food source of dugongs. Some dugongs can be sighted in water up to 10m deep in several areas including the Torres Strait, Northern Great Barrier Reef region and Hervey Bay in SouthEast Queensland where the water is wide, shallow and protected.
Dugongs are not found within waters containing a mean temperature of less than 19 degrees celsius. This is as a result of the production of sea grass, their main food source.
Seagrass is usually controlled at its deepest edge by the availability of light for photosynthesis. Exposure at low tide, wave action and associated turbidity and low salinity from fresh water inflow determine seagrass species survival at the shallow edge. Seagrass survive in sites sheltered from wave action or where there is entrapment of water at low tide protecting the seagrasses from exposure to heat at low tide.
Rainfall does not impact amongst the dugong's environment, but this factor affects the survival of this organism as excessive amounts of rainfall can potentially 'drown' the seagrass, eliminating a major food source for the dugong.
Two challenges that the dugong faces as a result of living in that environment.
Incidental catch
Dugongs face a major challenge of incidental by catch in large mesh nets used to capture gill set by commercial fishers. Incidental by catch is a major but largely unquantified cause of Dugong mortality in many countries in Australia. Scientists reported that in 2003, over a 15 month period in the Northern Territory, approximately 42% of the total mortality of Dugongs was caused from commercial causes including Barramundi fishing. Dugongs are more likely to be caught in nets amongst areas with a large population on seagrass.
Incidental catch of Dugongs also occur with shark nets. Although over the years Dugong mortality as a result of these nets have fortunately decreased as a result of fishers using baited hooks compared to nets.
Habitat loss and degradation
As a dugongs main habitat is amongst sea grass beds around the shallow coastal parts of Australia, the challenges of habitat loss and degradation are common. Sea grass beds are extremely sensitive and threats to these beds such as mining, natural disasters and trawling can potentially cause these habitats to be lost. These activities as well as other factors such as pollution can also increase the sedimentation and turbidity build up on these beds, ultimately covering and smothering the plant. This can cause the consumption of sun to decrease, preventing it from being able to go through photosynthesis which in return can cause the sea grass beds to die.
Dugongs face a major challenge of incidental by catch in large mesh nets used to capture gill set by commercial fishers. Incidental by catch is a major but largely unquantified cause of Dugong mortality in many countries in Australia. Scientists reported that in 2003, over a 15 month period in the Northern Territory, approximately 42% of the total mortality of Dugongs was caused from commercial causes including Barramundi fishing. Dugongs are more likely to be caught in nets amongst areas with a large population on seagrass.
Incidental catch of Dugongs also occur with shark nets. Although over the years Dugong mortality as a result of these nets have fortunately decreased as a result of fishers using baited hooks compared to nets.
Habitat loss and degradation
As a dugongs main habitat is amongst sea grass beds around the shallow coastal parts of Australia, the challenges of habitat loss and degradation are common. Sea grass beds are extremely sensitive and threats to these beds such as mining, natural disasters and trawling can potentially cause these habitats to be lost. These activities as well as other factors such as pollution can also increase the sedimentation and turbidity build up on these beds, ultimately covering and smothering the plant. This can cause the consumption of sun to decrease, preventing it from being able to go through photosynthesis which in return can cause the sea grass beds to die.
A structural adaptation of a dugong
Dugongs have very bad eyesight. As a result of this, dugongs have behaviourally adapted by feeling around for food and navigation through their snouts. These snouts are very sensitive and are covered in bristles, enabling the dugong to detect organisms such as sea grass beds. This also helps dugongs to survive as the waters in which they usually live are murky with high turbidity.
A behavioural adaptation of a dugong
Dugongs do not have any features which can be used for protection or self defence, instead they have learnt to adapt these responses and stay away from conflict. Dugongs over time have been hunted for various parts including meat and teeth. This has forced the dugongs to behaviourally adapt in becoming quite reserved and timid and have learnt to fear other animals and humans.
A physiological adaptation of a dugong
During the winter the dugongs habitat decreases in temperature. Dugongs as a result have adapted in response to this change and have learnt to travel long distances to warmer parts of the ocean, even if this means in deeper areas.
Research and tracking of dugongs have shown that Dugongs travel over 100km to warmer part of that bay during winter and then eventually return to their original bays during the warmer seasons.
Research and tracking of dugongs have shown that Dugongs travel over 100km to warmer part of that bay during winter and then eventually return to their original bays during the warmer seasons.
A rhythmic pattern displayed by the dugong - Reproduction
Reproduction of dugongs occur and change depending on the location of each herd. For example dugongs in Western Australia demonstrate behaviours such as defending their territories to attract females where as in other parts males may take part in competitions such as fighting to win over the females.
After a females gives birth to her young. The calf stays with its mother for approximately 1-2 years eventually leaving its mothers side and seeking their own mates between 6 and 9 years old.
After a females gives birth to her young. The calf stays with its mother for approximately 1-2 years eventually leaving its mothers side and seeking their own mates between 6 and 9 years old.
Interesting fact - While in the water, Dugongs can stick their heads out of the water by standing on their tails
Diagram 1 - Sites.google.com, (2015). Manatees - Sirenians 4/5/6 - 2014. [online] Available at: https://sites.google.com/site/sirenians2014/manatees [Accessed 17 Jul. 2015].
Diagram 2 - Sites.google.com, (2015). Manatees - Sirenians 4/5/6 - 2014. [online] Available at: https://sites.google.com/site/sirenians2014/manatees [Accessed 17 Jul. 2015].
Environment.gov.au,. 'Dugong Dugon — Dugong'. N.p., 2015. Web. 25 July 2015.