Unique quantitative Symbiodiniaceae signature of coral colonies revealed through spatio-temporal survey in Moorea

Abstract

One of the mechanisms of rapid adaptation or acclimatization to environmental changes in corals is through the dynamics of the composition of their associated endosymbiotic Symbiodiniaceae community. The various species of these dinoflagellates are characterized by different biological properties, some of which can confer stress tolerance to the coral host. Compelling evidence indicates that the corals’ Symbiodiniaceae community can change via shuffling and/or switching but the ecological relevance and the governance of these processes remain elusive. Using a qPCR approach to follow the dynamics of Symbiodiniaceae genera in tagged colonies of three coral species over a 10–18 month period, we detected putative genus-level switching of algal symbionts, with coral species-specific rates of occurrence. However, the dynamics of the corals’ Symbiodiniaceae community composition was not driven by environmental parameters. On the contrary, putative shuffling event were observed in two coral species during anomalous seawater temperatures and nutrient concentrations. Most notably, our results reveal that a suit of permanent Symbiodiniaceae genera is maintained in each colony in a specific range of quantities, giving a unique ‘Symbiodiniaceae signature’ to the host. This individual signature, together with sporadic symbiont switching may account for the intra-specific differences in resistance and resilience observed during environmental anomalies.

Temporal Variation in the Microbiome of Acropora Coral Species Does Not Reflect Seasonality

“…This symbiont switching in the rare biosphere has been found previously, but until recently, only following considerable bleaching events (Lewis and Coffroth, 2004; Boulotte et al, 2016) that did not occur even during peak summer temperatures during the present study. In the present study, switching was species-specific, suggesting some level of host regulation and supporting the idea of a host-specific “Symbiodiniaceae signature,” as outlined in Rouzé et al (2019).…”

Fish predation on corals promotes the dispersal of coral symbionts

“…To examine whether Symbiodiniaceae communities in corallivore feces constitute a potential source of symbiont cells for uptake by local corals, we characterized community compositions of Symbiodiniaceae in all our samples (fish feces, sediment and water) as well as in three common coral species (Acropora hyacinthus, Pocillopora species complex, and Porites lobata species complex; n = 12 per coral species; Table S1) by sequencing the internal transcribed spacer-2 (ITS-2) region of Symbiodiniaceae rDNA. The coral species examined here harbor unique Symbiodiniaceae communities [52,58] and are members of coral genera frequently targeted Table S2. For data used, see Additional file 2 by the corallivores in this study [50].…”

“…The impact of feces from different fish consumer groups on coral colony health and Symbiodiniaceae community assembly in adult corals should also be tested experimentally. Limited evidence suggests that adult coral colonies may take up novel Symbiodiniaceae species during or following environmental stress [8,34,58], but the influence of predator feces has not been examined. A tractable first step is to test whether adult coral colonies that have lost most or all of their symbionts (i.e.…”

“…Stony corals, for example, harbor single-celled dinoflagellates in the family Symbiodiniaceae and utilize their photosynthetic products to fuel the construction of reef frameworks [44]. Approximately 75% of spawning and 10% of brooding coral species acquire their Symbiodiniaceae from the environment with each generation [5], and adult corals may take up environmental Symbiodiniaceae cells to replenish their microbiomes following abiotic stress [8,34,58]. However, the dispersal mechanisms that make Symbiodiniaceae cells available to prospective host corals have not been resolved (but see [15,45]), and Symbiodiniaceae cell densities in environmental reservoirs appear relatively low (sediments: 10 1 -10 3 cells ml − 1 ; seawater: 10 0 -10 1 cells ml − 1 ; macroalgae: 10 2 -10 3 cells ml − 1 , Fig.…”

Fish predation on corals promotes the dispersal of coral symbionts

“…Stony corals, for example, harbor single-celled dinoflagellates in the family Symbiodiniaceae and utilize their photosynthetic products to fuel the construction of reef frameworks (Muscatine et al, 1984). Approximately 75% of spawning and 10% of brooding coral species acquire their Symbiodiniaceae from the environment with each generation (Baird et al, 2009), and adult corals may take up environmental Symbiodiniaceae cells to replenish their microbiomes following abiotic stress (Boulotte et al, 2016; Lewis and Coffroth, 2004; Rouzé et al, 2019). However, the dispersal mechanisms that make Symbiodiniaceae cells available to prospective host corals have not been resolved (but see Coffroth et al, 2006; Nitschke et al, 2016), and Symbiodiniaceae cell densities in environmental reservoirs appear relatively low (sediments: 10 1 -10 3 cells ml −1 ; seawater: 10 0 -10 1 cells ml −1 ; macroalgae: 10 2 -10 3 cells ml −1 , Figure 1; Castro-Sanguino and Sánchez, 2012; Fujise et al, in review ; Littman et al, 2008).…”