Microbial dynamics in shallow CO2 seeps system off Panarea Island (Italy)

Shallow-water hydrothermal vents are extreme environments characterized by high temperatures, low pH, and high CO2 concentrations; therefore, they are considered as suitable laboratories for studying the effect of global changes on marine microbes. We hypothesized a direct effect of vents on prokaryotic community structure and functioning in the Panarea Island’s hydrothermal system. Sampling was conducted along a 9-station transect characterized by three active emission points. The water column was stratified with a thermocline at 25 m depth and a deep chlorophyll maximum between 50 and 100 m. Prokaryotic abundance ranged from 0.2 to 1.5 × 109 cells L−1, prokaryotic carbon production from 2.4 to 75.4 ng C L−1 h−1, and exoenzymatic activities degrading proteins, phosphorylated compounds, and polysaccharides were on the order of 4–28, 2–31 and 0.2–4.16 nM h−1, respectively. While microbial abundance and production were shaped by the water column's physical structure, alkaline phosphatase...