MEPS 279:113-116 (2004)  -  doi:10.3354/meps279113

Initiation of symbiosis between the soft coral Heteroxenia fuscescens and its zooxanthellae

Zohar Pasternak1,2,*, Ami Bachar1, Avigdor Abelson2, Yair Achituv1

1Faculty of Life Sciences, Bar-Ilan University, Ramat-Gan 52900, Israel
2Institute for Nature Conservation Research, Tel-Aviv University, Tel-Aviv 69978, Israel

ABSTRACT: Symbiotic dinoflagellates of the genus Symbiodinium, commonly referred to as zooxanthellae, inhabit a large portion of the world¹s corals and are essential for the existence and well being of tropical reef ecosystems. The initiation of this symbiosis was studied using the Red-Sea soft coral Heteroxenia fuscescens. Results show that the motile algal cells are attracted to chemical substances emanating from the mouths of juvenile (zooxanthellae-free) polyps but not of adult (zooxanthellae-bearing) ones. The oral acquisition of symbionts is immediate; within 15 min of encountering the polyp, 15.6 ± 5.2 cells gain access into it. Once initial acquisition is concluded, the net number of algae within the polyp does not change significantly over the next 3 h, while algae continue to penetrate through and be expelled from the polyp mouth.


KEY WORDS: Algal acquisition · Symbiosis · Coral reef · Zooxanthellae · Chemotaxis


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