Responses of Heterotrophic Bacteria Abundance to added Trace Element Fe and Mn in the Inolgotrophic and Mesotrophic Zone of the Northern Yellow Sea

摘要

Heterotrophic bacteria play important roles in the biogeochemical cycling of key elements and serve as crucial links between dissolved organic carbon and sinking particles. Trace elements can directly and indirectly affect heterotrophic bacteria abundance. Two microcosm experiments were onboard in different nutrition levels of the Northern Yellow Sea in November 2011 to explore the responses of heterotrophic bacteria abundance of added Fe and Mn. Our results indicated that the influence of Mn and Fe on the abundance of heterotrophic bacteria was related to the nutrition level of the sea water. Mn can promote the growth of bacteria and increase the abundance of bacteria in oligotrophic seawater, while the impacted is limited within nutrient N and P is plentiful. And yet, Fe has the promoting effect of bacteria abundance in both oligotrophic and mesotrophic seawater, which is stronger in the oligotrophic water. Furthermore, high concentration of Fe has stronger positive impact.