Ecology of the Indonesian Seas by Tomas Tomascik & Anmarie J. Mah

Author:Tomas Tomascik & Anmarie J. Mah [Tomascik, Tomas & Mah, Anmarie J.]
Language: eng
Format: epub
Tags: nature, Ecosystems & Habitats, Oceans & Seas, ecology, Travel, Asia, Southeast, Forests & Rainforests, Regional
ISBN: 9781462905027
Google: qwzRAgAAQBAJ
Publisher: Tuttle
Published: 2013-02-05T20:27:04+00:00

Figure 8.9. Chemical warfare is a common occurrence on the reef. Competition for space between octocorals and scleractinians, and other benthic organisms, is intense. A) Sarcophyton and Sinularia monopolize many patches at the expense of other benthic organisms. B) Using its powerful chemical defense capabilities (i.e., highly toxic metabolites), this Sinularia sp. can grow in an optimal habitat, undisturbed by the nearby assemblage of feather stars, Oxycomanthus bennetti (Crinoidea).

Photos by Tomas and Anmarie Tomascik, Koon Island, Halmahera Sea.

Nutritional Aspects of Symbiosis. It seems that the main advantage of the symbiotic association for the soft corals is nutritional, since photosynthetic rates of octocorals range between 0.1 to 3.2 mg C.g" dry weight of colony per day, and are comparable to the scleractinians (Sorokin 1991) (table 8.2). The ratio of photosynthesis to respiration (P/R) in symbiotic octocorals studied thus far is usually greater than one, which suggests that the animals are functionally autotrophic systems (Sorokin 1991). For example, Xenia relies almost entirely on photosynthates from its zoox anthellae endosymbionts, and is a very poor heterotroph. Heterotrophic-feeding may be used purely for the supplementary uptake of nitrogen and phosphorus, which are needed for protein syntheses and energy transfer. The continuously pulsating polyps of Xenia spp. are frequently mistaken for a feeding behaviour by visitors to the reefs. The polyp contractions are purely for the intake of respiratory water (Morton 1990).

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