Abstract
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 octocoralsLitophytonsp. andStereonephthyasp. 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.Litophytonsp. andStereonephthyasp. hostedDurusdiniumandGerakladium, respectively. Both genera represent singular associations, with the latter further establishing the first solid report ofGerakladiumin octocorals. Traits distinguished two groups explained by the two partnerships considered.Litophytonsp. associated withDurusdiniumhad significantly higher organic matter, chlorophyll (chl)a, total lipid and lower chlc/chlaratio thanStereonephthyasp. associated withGerakladium.The δ15N in the host and algae, as well as δ13C in the host were also higher inLitophytonspecies. Although no significant difference was observed in the δ13C of the algae,Litophytonsp. presented a significantly higher variance for this trait and for chlacontent thanStereonephthyaspecies. Altogether, the traits examined suggested contrasting performances among the two octocorals. Both octocoral species clearly deviate from an autotrophic diet.Litophytonsp. appears to complement its heterotrophic diet with photosynthetically acquired energy, whileStereonephthyasp. 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.
Highlights
Octocorals are important contributors to the living threedimensional structure of the marine animal forests (Sánchez, 2016)
Higher δ15N values were observed in Litophyton sp. animal host and algal fractions compared to Stereonephthya sp. (Figure 3)
It was the case for δ13C values of the animal host fraction, but not for the algal fraction in which there was no significant difference between the two species
Summary
Octocorals are important contributors to the living threedimensional structure of the marine animal forests (Sánchez, 2016). Mean field theory (the study of the behavior of the mean while ignoring variance, Violle et al, 2012) still remains widely adopted in trait-based community ecology, especially in studies focusing on hyperdiverse ecosystems such as the coral reefs (Hughes et al, 2018; McWilliam et al, 2018) It provides a wide array of opportunities to improve our understanding of organism responses, in species where symbiosis is expected to mediate niche differentiation and expansion (see Gerz et al, 2018). We delineated species performance niches in a constant environment and discussed differences among the two targeted species in light of the association they maintained with their respective algal partners
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
