Abstract
In 2021, the rapid emergence of mucilage in the Marmara Sea raised concerns about its environmental impact. This study compares mucilage and seawater samples from 16 stations across the Marmara Sea using shotgun metagenomic sequencing and bioinformatics. Sampling was conducted from April to September 2021 across varying oceanographic conditions, including different temperatures and salinity levels, to identify changes in the microbial community. Results showed that 58% of the reads in mucilage samples could not be assigned to any taxon, indicating significant microbial "dark matter." Clean seawater was characterized by a higher presence of Euryarchaeota, Proteobacteria, and Rhodothermaeota, while Chlamydiae and Fusobacteria were dominant in mucilage. Pre-mucilage seawater samples showed microbial compositions similar to mucilage, suggesting a link between microbiome imbalance and mucilage formation. These findings provide a comparative metagenomic analysis highlighting the need for further studies to understand mucilage's environmental impact and develop early warning strategies.