Dynamics of coral-associated bacterial communities acclimated to temperature stress based on recent thermal history

Abstract

Seasonal variation in temperature fluctuations may provide corals and their algal symbionts varying abilities to acclimate to changing temperatures. We hypothesized that different temperature ranges between seasons may promote temperature-tolerance of corals, which would increase stability of a bacterial community following thermal stress. Acropora muricata coral colonies were collected in summer and winter (water temperatures were 23.4–30.2 and 12.1–23.1 °C, respectively) from the Penghu Archipelago in Taiwan, then exposed to 6 temperature treatments (10–33 °C). Changes in coral-associated bacteria were determined after 12, 24, and 48 h. Based on 16S rRNA gene amplicons and Illumina sequencing, bacterial communities differed between seasons and treatments altered the dominant bacteria. Cold stress caused slower shifts in the bacterial community in winter than in summer, whereas a more rapid shift occurred under heat stress in both seasons. Results supported our hypothesis that bacterial community composition of corals in winter are more stable in cold temperatures but changed rapidly in hot temperatures, with opposite results for the bacterial communities in summer. We infer that the thermal tolerance ranges of coral-associated bacteria, with a stable community composition, are associated with their short-term (3 mo) seawater thermal history. Therefore, seasonal acclimation may increase tolerance of coral-associated bacteria to temperature fluctuations.

Comparison of microbiomes of cold-water corals Primnoa pacifica and Primnoa resedaeformis, with possible link between microbiome composition and host genotype

“…In addition to appearing as core members of the P. resedaeformis microbiome, Vibrionaceae bacteria were recently identified as core members of the microbiome of stony coral Cladocora caespitosa 81 , and appear in the microbiomes of corals worldwide 19 , 21 , 22 , 35 – 37 , 41 , 42 , 45 , 54 , 63 – 65 , 71 , 76 , 82 – 85 . Though Vibrios are often associated with coral disease, their widespread association with healthy corals suggests an important function in the normal functioning of the coral holobiont.…”

Comparative genomics: Dominant coral-bacterium Endozoicomonas acroporae metabolizes dimethylsulfoniopropionate (DMSP)

“…We analyzed microbial community data publically available from three different studies-1) our laboratory's previous study [34]; (2) a study of coral-associated bacterial communities in the Red Sea [59]; and (3) coral-associated bacterial community from reefs in the east and west coast of Australia, including Ningaloo Reef, Lizard Island, reefs from the northern sector of the Great Barrier Reef, and Lorde Howe Island [60]-to profile the abundance of E. acroporae strains in different coral species from Penghu Archipelago, Taiwan; the Red Sea, Saudi Arabia; and east and west Australia. All three studies used the same operational taxonomic unit (OTU) clustering threshold of 97% and the Greengenes database (v99) [61] for taxonomic assignment.…”

“…All three studies used the same operational taxonomic unit (OTU) clustering threshold of 97% and the Greengenes database (v99) [61] for taxonomic assignment. OTU abundance profiles and their representative sequences were downloaded from supplementary materials in Shiu et al [34], Ziegler et al [59], and Pollock et al [60]. We performed similarity searches on all OTU sequences from the three studies against the in-house blast [62] database of all available Endozoicomonas 16S rRNA gene sequences with standalone blastn [62] and profiled the relative abundance of E. acroporae strains at the three locations with e-value < 1e-5 and identity threshold ≥ 99%.…”

“…Of all the organisms in the tremendously diverse coral holobionts, genomes of Endozoicomonas species have been widely studied for their functional and ecological roles [29,30]. Endozoicomonas species were found to be abundant in the coral holobionts across the globe [31] and are hypothesized to be potential indicators of coral health [32] -they have high abundance in healthy corals and a relatively low abundance in diseased or stressed corals [33][34][35]. Furthermore, nearly complete and draft genomes of Endozoicomonas species isolated from corals and other marine invertebrates [29,36,37] have recently been assembled.…”

Exceptional but vulnerable microbial diversity in coral reef animal surface microbiomes

“…This genus has been isolated from coral disease lesions [46,47]. It has also been recovered from corals exposed to fish farm effluents and in thermally-stressed corals [48,49]. Here, while the corals were apparently healthy and sampled far from coastal cities (SM1-1), the high temperatures at the time of sampling (SM1-2), together with a potential contamination of the lagoon by human faeces due to the absence of effluent treatment in Mayotte [50] may explain the presence of this genus.…”