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Viable algae released by the seastar Dermasterias imbricata feeding on the symbiotic sea anemone Anthopleura elegantissima

Bachman, Sarah, Muller-Parker, Gisèle
Marine biology 2007 v.150 no.3 pp. 369-375
Echinodermata, digestion, ecosystems, feces, hosts, pellets, photosynthesis, pigments, predation, predators
Echinoderms are major predators of anemones in temperate ecosystems. The fate of two algae, zooxanthellae and zoochlorellae, after their host anemone (Anthopleura elegantissima Brandt) was consumed by the leather star Dermasterias imbricata Grube was determined in experiments conducted in July and August 2004. Productivity, photosynthetic pigments, and mitotic index (percent of cells dividing) were used as indicators of algal health; algae released after leather stars consumed their host were compared with algae freshly isolated from anemones. Two types of waste products contained algae: pellets resulting from extraoral digestion, and feces. Zooxanthellae and zoochlorellae isolated from these waste products were photosynthetic, although to different extents. For algae from feces and pellets, light-saturated photosynthetic rates (Pₘₐₓ) were 85 and 13%, respectively, of Pₘₐₓ of freshly isolated zooxanthellae; and were 20 and 46%, respectively, for zoochlorellae. The photosynthetic pigments and mitotic index (percent of dividing cells) were not altered by the feeding activities of the leather star. These results show that algae released by seastar predation on their hosts remain viable, and are hence available for establishing symbioses in A. elegantissima and other potential hosts.