Negative parental and offspring environmental effects of macroalgae on coral recruitment are linked with alterations in the coral larval microbiome

In this work, we study the effect of dense macroalgal assemblages on the brooding coral Pocillopora acuta. We hypothesized that macroalgal assemblages may have negative parental and environmental effects on coral recruitment and that these effects may be mediated by alterations in the coral and substrate microbiome (16S rRNA). To test these assumptions, we conducted a manipulative field experiment in which we compared coral (i.e., adults and larvae) and microbenthic substrate microbiomes between algal-removed and algal-dominated bommies within a single fringing reef in Mo'orea, French Polynesia. Then, we assessed the relative influence of parental and environmental effects on coral recruitment success by reciprocally exposing coral larvae from two parental origins (i.e., colonies originating from algal-removed vs. algal-dominated bommies) to algal-removed and algal-dominated environmental conditions in a series of survival and settlement experiments. Published in Royal Society Open Science (RSOS240187)