Response of seaweed associated microbiome to environmental disturbances from the Gulf of Aqaba, Jordan

The seaweed surface mediates interactions between the alga and its environment. Associated microbial communities can influence host morphology, organic matter consumption, and defence. Environmental drivers interact with these communities, affecting host fitness. This study investigated the influence of anthropogenic disturbances on prokaryotic communities associated with the green seaweed Ulva lactuca Linnaeus in the Gulf of Aqaba, Jordan. Seaweed samples were collected from three impacted sites during winter and summer. The composition of seaweed-associated microbial communities (SAMCs) was determined using 16S rRNA gene amplicon sequencing targeting the V4 hypervariable region using the Illumina NextSeq 500 platform. The results revealed significant seasonal shifts in SAMC composition, with Firmicutes dominating in winter and Bacteroidetes and Proteobacteria being more prevalent in summer. Higher alpha diversity was observed in summer samples, possibly due to increased nutrients availability. Environmental parameters, notably pH and dissolved oxygen, strongly influenced the distribution of algae-associated bacterial groups, accounting for 77.3 % of the observed variation in SAMCs between seasons. This study provides valuable insights into the dynamic nature of SAMCs in response to diverse environmental disturbances. Our findings underscore the ecological significance of SAMCs and their potential utility as sensitive indicators of environmental perturbations within marine ecosystems. Furthermore, this research contributes to the development of strategies aimed at the conservation and sustainable management of vulnerable coastal ecosystems.