Parental and early life stage environments drive establishment of bacterial and dinoflagellate communities in a common coral

Abstract

The establishment of coral microbial communities in early developmental stages is fundamental to coral fitness, but its drivers are largely unknown, particularly for bacteria. Using an in situ reciprocal transplant experiment, we examined the influence of parental, planulation and early recruit environments on the microbiome of brooded offspring in the coral Pocillopora damicornis. 16S rRNA and ITS2 rDNA gene metabarcoding showed that bacterial and microalgal endosymbiont communities varied according to parental and planulation environments, but not with early recruit environment. Only a small number of bacterial strains were shared between offspring and their respective parents, revealing bacterial establishment as largely environmentally driven in very early life stages. Conversely, microalgal communities of recruits were highly similar to those of their respective parents, but also contained additional low abundance strains, suggesting both vertical transmission and novel ('horizontal') acquisition. Altogether, recruits harboured more variable microbiomes compared to their parents, indicating winnowing occurs as corals mature.

The roles of age, parentage and environment on bacterial and algal endosymbiont communities in Acropora corals

“…Hydra , for instance, has highly diverse and variable bacterial communities in early life stages but diversity is drastically decreased in the adult stage (Franzenburg et al, ). Several previous studies on corals are also in agreement with our findings (Epstein et al, ; Lema et al, ; Littman, Willis, & Bourne, ). Lema et al () found distinct bacterial communities in the larval stage, early recruit stage (one and 2 weeks old) and recruit/juvenile stages (3, 6, 12 months old) of Acropora millepora .…”

“…A high abundance of Endozoicomonas spp. has been found in adult corals across geographical regions (Epstein et al, 2019;Morrow, Moss, Chadwick, & Liles, 2012;Pollock et al, 2018). For example, this taxon accounted for >70% of the bacterial communities of Pocillopora damicornis from Australia (van and…”

“…Conversely, bacterial communities of conspecific corals may remain stable despite seasonal environmental variations (Littman, Willis, Pfeffer, & Bourne, ) or exposure to different pH conditions (Meron et al, ; Webster et al, ; Zhou et al, ). While the succession of coral‐associated bacterial communities is poorly studied, community winnowing during coral development into adulthood is an emerging pattern (Epstein, Torda, Munday, & van Oppen, ; Lema, Bourne, & Willis, ; Littman, Willis, Pfeffer, et al, ).…”

Co‐dynamics of Symbiodiniaceae and bacterial populations during the first year of symbiosis with Acropora tenuis juveniles

“…Furthermore, we did not recover Endozoicomonas‐ related sequences until T 3 , with the highest relative abundance in the final time point (T 8 ). Roseobacter and Burkholderia—Paraburkholderia may also be important for juvenile health by way of nitrogen fixation (Damjanovic, Blackall, Webster, & van Oppen, ; Epstein et al, ; Leite et al, ), although more targeted sequencing is needed to determine if these represent true coral symbionts (e.g., Ainsworth et al, ).…”

“…The acquisition and development of bacterial and Symbiodiniaceae communities in juvenile varies throughout early stages of coral ontogeny (Abrego, van Oppen, & Willis, , ; Fieth, Gauthier, Bayes, Green, & Degnan, ; Lema, Bourne, & Willis, ; Quigley, Bay, & Willis, ; Quigley, Willis, & Bay, ) likely regulated by both host and environmental factors (Poland & Coffroth, ; Quigley, Bay, et al, ; Quigley, Willis, et al, ; Souza et al, ). In the few species examined to date, the composition of bacterial communities is largely influenced by acquisition from the environmental pool and to a lesser extent by vertical, parental transmission (Apprill, Marlow, Martindale, & Rappé, ; Epstein, Torda, Munday, & van Oppen, ; Leite et al, ; Lema et al, ; Sharp, Distel, & Paul, ; Zhou et al, ). Once acquired, community shifts are common throughout ontogeny across a range of invertebrate groups (Douglas & Werren, ).…”