Marine heterotrophic bacteria play key roles in the biogeochemical cycles. Their response to temperature is crucial to understanding how marine ecosystems respond to the projected increasing global warming. To investigate the temperature effects on bacterial growth, we conducted short-term temperature-modulated dilution experiments on natural communities at two subtropical coastal sites with contrasting environmental conditions (i.e., EO Station and WE Station) every month for one year. We compared the changes in bacterial growth rate (μ) at five different temperatures and estimated their temperature sensitivity regarding activation energy (E_a). Our results showed that: (1) The abundance of bacteria varied seasonally with high value in Summer and was positively correlated with temperature and Chl a concentration; (2) the E_a of growth rate at EO station (0.52 eV, 95 % confidence interval [CI] = 0.30 - 0.74 eV) was slightly greater than that of WE station (0.33 eV, 95 % [CI]= 0.20 - 0.46 eV); (3) In particular, the thermal response curves of bacterial growth rate in every month were not all consistent with typical unimodal patterns, in which some curves had second rise at high temperature. It may be due to the changes in natural bacteria communities during incubation, which requires further investigation. Our study reveals the various responses of the natural bacterial communities to experimental warming, providing insights into the potential changes in marine bacteria and related food webs in future oceans under climate warming.

warming,bacteria,growth rate,activation energy,dilution