The microbiome associated with the reef builder neogoniolithon sp. In the eastern mediterranean

The development of coastal vermetid reefs and rocky shores depends on the activity of several reef builders, including red crustose coralline algae (CCA) such as Neogoniolithon sp. To in-itiate studies on the interaction between Neogoniolithon sp. and its associated bacteria, and their impact on the algae physiological performance, we characterized the bacterial community by 16S rRNA gene sequencing. These were extracted from the algal tissue and adjacent waters along two sampling campaigns (during winter and spring), in three study regions along a reef in the east Mediterranean Israeli coast and from laboratory‐grown algae. The analysis revealed that aquaria and field communities differ substantially, suggesting that future research on Neogoniolithon sp. interaction with its microbiome must rest on aquaria that closely simulate coastal conditions. Some pro-karyote classes found associated with the alga tissue were hardly detected or absent from surround-ing water. Further, bacterial populations differed between sampling campaigns. One example is the presence of anaerobic bacteria and archaea families in one of the campaigns, correlating with the weaker turbulence in the spring season, probably leading to the development of local anoxic condi-tions. A better understanding of reef‐building activity of CCA and their associated bacteria is nec-essary for assessment of their resilience to climate change and may support coastal preservation efforts.