Impact of marine heatwave on microbiome of mediterranean gorgonians

In this study, we sampled two gorgonian species (P.clavata and C.rubrum) with different visual health states (0% and 90% of tissue loss) during the record-breaking heatwave of 2022. This is the first time that gorgonians with obvious signs of tissue damage have been sampled to investigate changes in their bacterial communities. The gorgonians were collected in two protected areas (the Calanques National Park in France, and the Portofino Marine Park in Italy) that experienced different MHW intensities, with measurements reaching 27C and 26C at depths of 15 m and 30 m, respectively in the Calanques National Park and 19.8C at 35m depths in Portofino. The sampling sites are suited to study the impact of the 2022 MHW because they are located in protected areas with no anthropogenic threats other than seawater warming. The main objective of this study was to characterize the species-specific composition of bacterial communities associated with emblematic gorgonians from the Mediterranean Sea, in relation to their physiological conditions and collection sites. To this end, we analyzed a total of 96 samples from 7 collection sites and 2 species by amplicon sequencing of the 16S rRNA gene. This study provides important information on how gorgonian-associated microbiomes respond to thermal stress and will enable a better conservation and protection of Mediterranean MAFs.

本研究在2022年破纪录的海洋热浪（Marine Heatwave, MHW）期间，采集了两种柳珊瑚（gorgonian）样本，物种为P.clavata与C.rubrum，二者具有不同的外观健康状态——组织缺损率分别为0%与90%。本研究首次针对出现明显组织损伤迹象的柳珊瑚开展采样，以探究其细菌群落的动态变化。本次采样的柳珊瑚分别采自两处受保护海域：法国卡朗格国家公园（Calanques National Park）与意大利波托菲诺海洋公园（Portofino Marine Park），两处海域经历了不同强度的海洋热浪，其中卡朗格国家公园在15米与30米水深处的水温分别达27℃与26℃，波托菲诺海域35米水深处的水温为19.8℃。本次采样点位适宜开展2022年海洋热浪影响研究，因为所有采样点均位于受保护区域，仅受海水升温影响，无其他人为活动威胁。本研究的核心目标是解析地中海地区代表性柳珊瑚共生细菌群落的物种特异性组成，并探讨其与宿主生理状态及采样点位的关联。为此，我们通过16S rRNA基因扩增子测序（amplicon sequencing）技术，对来自7个采样点位、2个物种的共计96份样本进行了分析。本研究阐明了柳珊瑚共生微生物组对热胁迫的响应机制，将为地中海MAFs的科学保护提供关键参考依据。