Like many corals, staghorn corals such as Acropora granulosa have a special symbiotic relationship with algae, called zooxanthellae. The algae gain a safe, stable environment within the coral's tissues, while the coral receives nutrients produced by the algae through photosynthesis. While, on average, zooxanthellate coral can obtain around 70 percent of its nutrient requirements from photosynthesis by zooxanthellae, the coral may also feed on zooplankton Acropora granulosa and its zooxanthellae are very sensitive to changes in water temperature and acidity. Any increase in water temperature greater than one or two degrees Celsius above the average can stress the coral and cause ‘bleaching’, a phenomenon in which the coral expels it zooxanthellae and turns white Staghorn corals are reef-building, or ‘hermatypic’ corals, and are incredibly successful at building reefs for two main reasons. Firstly, they have light skeletons which allow them to grow quickly and out-compete their neighbouring corals. Secondly the corallite of a new polyp, is built by specialised ‘axial’ corallites. These axial corallites form the tips of branches and, as a result, all the corallites of a colony are closely interconnected and can grow in a coordinated manner. This means that by harnessing the sun's energy, staghorn corals are able to grow relatively rapidly and form vast reef structures, but are constrained to live near the water surface Very little is known about the specific reproductive biology of Acropora granulosa, although it is likely to be able to reproduce both sexually and asexually. Asexual reproduction occurs via fragmentation, when a branch breaks off a colony, reattaches to the substrate and grows Acropora range
Acropora granulosa is found from the Red Sea and south-west and northern Indian Ocean, to the central Indo-Pacific, and the west and central Pacific Acropora habitat
Colonies of Acropora granulosa are found in most subtidal reef environments, particularly on reef slopes that are protected from wave action Acropora status
Acropora granulosa is classified as Near Threatened (NT) on the IUCN Red List Acropora threats
With an estimated 20 percent of the world’s coral reefs already destroyed, Acropora granulosa faces many of the threats that are affecting coral reefs globally Worldwide there is increasing pressure on coastal resources resulting from human population growth and development. There has been a significant increase in domestic and agricultural waste in the oceans, poor land-use practices that result in an increase in sediment running on to the reefs, and over-fishing, which can have ‘knock-on’ effects on the reef However, the major threat to corals is global climate change, with the expected rise in ocean temperatures increasing the risk of coral bleaching, often resulting in the death of the coral Climate change may also lead to more frequent, severe storms, which can damage reefs, and rising carbon dioxide levels may make the ocean increasingly acidic. Such stresses can also make corals more susceptible to disease, parasites and predators, such as the crown-of-thorns sea star (Acanthaster planci) Acropora species are also in the top three genera collected for the aquarium trade, and harvesting of wild colonies of Acropora granulosa may pose some threat to this species Acropora conservation
In addition to being listed on Appendix II of the Convention on International Trade in Endangered Species (CITES), which makes it an offence to trade this species internationally without a permit, Acropora granulosa also forms part of the reef community in several Marine Protected Areas (MPAs)
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- Simple plants that lack roots, stems and leaves but contain the green pigment chlorophyll. Most occur in marine and freshwater habitats.
- Asexual reproduction
- Reproduction that does not involve the formation of sex cells (‘gametes’). In many species, asexual reproduction can occur by fission (or in plants ‘vegetative reproduction’); part of the organism breaks away and develops into a separate individual. Some animals, including vertebrates, can develop from unfertilised eggs; this process, known as parthenogenesis, gives rise to offspring that are genetically identical to the parent.
- A groinvertebrates_marine
IUCN Red List (February, 2011)
CITES (February, 2011)
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Wallace, C.C. (1999) Staghorn Corals of the World: A Revision of the Coral Genus Acropora. CSIRO, Collingwood, Australia.
Acropora Biological Review Team. (2005) Atlantic Acropora Status Review Document. Report to National Marine Fisheries Service, Southeast Regional Office.
World Register of Marine Species - Acropora granulosa (February, 2011)
Veron, J.E.N. (1986) Corals of Australia and the Indo-Pacific. Angus and Robertson Publishers, UK.
Guest, J.R., Baird, A.H., Goh, B.P.L. and Chou, L.M. (2005) Reproductive seasonality in an equatorial assemblage of scleractinian corals.Coral Reefs, 24: 112-116.
Baird, A.H., Marshall, P.A. and Wolstenholme, J. (2000) Latitudinal Variation in the Reproduction of Acropora in the Coral Sea. Proceedings 9th International Coral Reef Symposium, Bali, Indonesia.
Guest, J.R., Baird, A.H., Goh, B.P.L. and Chou, L.M. (2005) Seasonal reproduction in equatorial reef corals. Invertebrate Reproduction and Development, 48(1–3): 207-218.
Wilkinson, C. (2004) Status of Coral Reefs of the World: 2004. Volume 3. Australian Institute of Marine Science, Townsville, Australia.
Carpenter, K.E. et al. (2008) One-third of reef-building corals face elevated extinction risk from climate change and local impacts. Science, 321: 560-563.
Miththapala, S. (2008) Coral Reefs. Coastal Ecosystems Series (Volume 1). Ecosystems and Livelihoods Groinvertebrates_marine