As you all know from my last post that over break I visited a marine pelagic biome. But now something horrible has happened! The tiger sharks in Shark Bay, Australia have gone extinct!
PC: Rob Stewart/Sharkwater
The tiger shark is a keynote species. A keynote species is a type of species that has a disproportionately large effect on its ecosystem in relation to its abundance. In Shark Bay, Australia, the tiger shark was the main predator of Dugongs and Green Sea Turtles.
PC: Julien Willem, 1 July 2008
PC: Alexander Vasenin, 9 April 2010
Both the Dugongs and Green Sea Turtles feed off of nutritious sea grass. The tiger sharks usually are found in waters where sea grass is abundant, but since they are extinct, they are not there any more, leaving the Dugongs and Green Sea Turtles to feed freely. When grazing, the Dugongs remove the entire seagrass plant. This disrupts the structure of the seagrass meadow, the nutrients content, and the surrounding environment. When grazing, Green Sea Turtles remove the top of the seagrass blades. The presence of tiger sharks distributed the grazing of turtles. Without the tiger sharks the seagrass population will become very scarce and this will affect not only species that rely on eating the seagrass but also the bottom sea communities.
*This post is for a biology project. Tiger sharks are not really extinct in Australia currently.
Sources:
http://oceana.org/sites/default/files/o/fileadmin/oceana/uploads/Sharks/Predators_as_Prey_FINAL_FINAL.pdf
The tiger shark is a keynote species. A keynote species is a type of species that has a disproportionately large effect on its ecosystem in relation to its abundance. In Shark Bay, Australia, the tiger shark was the main predator of Dugongs and Green Sea Turtles.
Both the Dugongs and Green Sea Turtles feed off of nutritious sea grass. The tiger sharks usually are found in waters where sea grass is abundant, but since they are extinct, they are not there any more, leaving the Dugongs and Green Sea Turtles to feed freely. When grazing, the Dugongs remove the entire seagrass plant. This disrupts the structure of the seagrass meadow, the nutrients content, and the surrounding environment. When grazing, Green Sea Turtles remove the top of the seagrass blades. The presence of tiger sharks distributed the grazing of turtles. Without the tiger sharks the seagrass population will become very scarce and this will affect not only species that rely on eating the seagrass but also the bottom sea communities.
*This post is for a biology project. Tiger sharks are not really extinct in Australia currently.
Sources:
http://oceana.org/sites/default/files/o/fileadmin/oceana/uploads/Sharks/Predators_as_Prey_FINAL_FINAL.pdf
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