AUTHOR=Hsu Tsai-Hsuan Tony , Carlu Lilian , Hsieh Yunli Eric , Lai Tzu-Yu Angel , Wang Ching-Wei , Huang Ching-Yun , Yang Shan-Hua , Wang Pei-Ling , Sturaro Nicolas , Denis Vianney 

TITLE=Stranger Things: Organismal Traits of Two Octocorals Associated With Singular Symbiodiniaceae in a High-Latitude Coral Community From Northern Taiwan

JOURNAL=Frontiers in Marine Science

VOLUME=7

YEAR=2020

URL=https://www.frontiersin.org/journals/marine-science/articles/10.3389/fmars.2020.606601

DOI=10.3389/fmars.2020.606601

ISSN=2296-7745

ABSTRACT=<p>Scrutinizing the traits of octocorals that could affect their physiological performance becomes increasingly important as several of these species are observed to become dominant on reefs pressured by the Anthropocene. In the present study, we compare the organismal traits of two branching octocorals <italic>Litophyton</italic> sp. and <italic>Stereonephthya</italic> sp. commonly populating in sympatry the high-latitude coral communities of northern Taiwan. Using 13 traits, we describe and compare performance traits in these two symbiotic species that we discuss in light of the association they maintain with their algal partners. <italic>Litophyton</italic> sp. and <italic>Stereonephthya</italic> sp. hosted <italic>Durusdinium</italic> and <italic>Gerakladium</italic>, respectively. Both genera represent singular associations, with the latter further establishing the first solid report of <italic>Gerakladium</italic> in octocorals. Traits distinguished two groups explained by the two partnerships considered. <italic>Litophyton</italic> sp. associated with <italic>Durusdinium</italic> had significantly higher organic matter, chlorophyll (chl) <italic>a</italic>, total lipid and lower chl <italic>c</italic>/chl <italic>a</italic> ratio than <italic>Stereonephthya</italic> sp. associated with <italic>Gerakladium.</italic> The δ<sup>15</sup>N in the host and algae, as well as δ<sup>13</sup>C in the host were also higher in <italic>Litophyton</italic> species. Although no significant difference was observed in the δ<sup>13</sup>C of the algae, <italic>Litophyton</italic> sp. presented a significantly higher variance for this trait and for chl <italic>a</italic> content than <italic>Stereonephthya</italic> species. Altogether, the traits examined suggested contrasting performances among the two octocorals. Both octocoral species clearly deviate from an autotrophic diet. <italic>Litophyton</italic> sp. appears to complement its heterotrophic diet with photosynthetically acquired energy, while <italic>Stereonephthya</italic> sp. tends to be more specialized and benefits relatively little from its symbiotic relationship. Our study calls for greater consideration of the individual variation in octocoral physiology and in the definition of their ecological strategies.</p>