MEPS 545:175-187 (2016)  -  DOI: https://doi.org/10.3354/meps11606

ABSTRACT: Anthopleura elegantissima, the most abundant intertidal sea anemone on the Pacific coast of North America, naturally occurs in 3 distinct symbiotic states: zooxanthellate (hosting the dinoflagellate Symbiodinium muscatinei), zoochlorellate (hosting the chlorophyte Elliptochloris marina), and asymbiotic (lacking symbionts). To document the effect of symbiotic state on host lipids, 10 A. elegantissima in each symbiotic state were collected from the same location and habitat. The symbiont and host tissues were separated, and the fatty acid profiles were compared (1) between the 2 symbionts themselves, (2) among anemones in the 3 symbiotic states, and (3) between the symbionts and their host anemones. Significant differences were present in the fatty acid profiles of S. muscatinei and E. marina, with docosahexaenoic acid (DHA) abundant in S. muscatinei, and oleic and α-linolenic acids abundant in E. marina. Zooxanthellate anemone tissues had significantly higher total fatty acid content than did tissues of zoochlorellate hosts, supporting suggestions that S. muscatinei is more productive and thus a better symbiont. Asymbiotic sea anemones had significantly lower concentrations of total fatty acids than hosts in either symbiotic state and overall lower levels of most fatty acids. Previous research suggests that symbionts translocate specific fatty acids to their coral hosts, but there was no evidence for fatty acid translocation in A. elegantissima. Our results support the suggestions that hosting photosymbionts increases the fitness of A. elegantissima and that S. muscatinei is a better symbiotic partner.

KEY WORDS: Anthopleura elegantissima · Elliptochloris marina · Fatty acid content · Sea anemone · Symbiodinium muscatinei · Symbiosis · Zoochlorellae · Zooxanthellae