21 April 2015

Vegetarians of the Sea

Dugong feeding in sediment, photo from: www.arkive.org

Dugongs (Dugong dugon) commonly known as sea cow, can be found in at least 48 countries along the coasts of the western Pacific and Indian oceans. They can grow up to an average of 3 meters and can weigh at around 2,200 lbs [1]. Being the only marine herbivorous mammal, they mostly feed on seagrass as they are highly low in fiber and nutrients such as nitrogen and starch and it’s easily digestible [2]. Other herbivorous mammals would be its close relative, the Manatees which are commonly found in coastal waters and rivers such as the Amazon River

Dugongs can consume an average of 77lbs of sea grass per day [5]. About 97% of their diet consists of different species of seagrass as the remaining are algae. These numbers however can change depending on the abundance of food species and its ecological distribution [4]. As much as they prefer to be at shallow waters, they can also be found in depths up to 37 meters because of the presence of some deepwater seagrass habitats [3]. There are still a lot of threats that this animal faces. Because of human activities such as development, pollution and some cases of by-catch, the dugong population is decreasing. Another threat is food availability, and it causes a delay in breeding. These threats make habitat conservation a critical issue [3]. Dugongs are now classified as Vulnerable (VU) according to the IUCN red list [6].

To know more about dugongs, visit SeaLifeBase.

[1] Reeves, R. R., Stewart, B. S., Clapham, P. J., and Powell, J. A. (2002) Guide to Marine Mammals of the world. New York, NY: Chanticleer Press, Inc. 527p.

[2] Marsh, H. (2009) Dugong Dugong dugon. In pp. 332-335, Perrin, W.F., Wursig, B., Thewissen, J.G.M. (2009) Encyclopedia of Marine Mammals Second Edition. Academic Press: London. 1316pp.

[3] Marsh, H. (2002) Dugong: Status Report and action plans for countries and territories Early warning and assessment report series. UNEP: Nairobi. 162p.

[4] Johnstone, I.M., and Hudson, B.E.T. (1981) The Dugong Diet: Mouth sample analysis. Bulletin of Marine Science, 31(3):681-690

[5] Gaus, C., Donohue, M.O., Connell, D., Mueller, Jochen., Hynes, D., and Paepke, Olaf. (2004) Exposure and potential risks of Dioxins to the Marine Mammal Dugong. Organohalogen Compounds. 66:1159-1166

[6] Marsh, H. (2008). Dugong dugon. The IUCN Red List of Threatened Species. Version 2014.3. <www.iucnredlist.org>. [Accessed 16/04/2015].

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