Spatial and vertical distribution of aerobic and anaerobic dark inorganic carbon fixation in coastal tropical lake sediments

• The process of chemosynthesis can represent an important source of organic matter and energy across the benthic zone. However, its detailed vertical distribution and importance in relation to other microbial processes are still poorly investigated in inland aquatic ecosystems. Here, we determined the rates of dark inorganic carbon fixation (DCF) compared to heterotrophic bacterial production (BP) and oxygen consumption (SOC) across a depth profile of oxic to anoxic sediments in the littoral zone of nine tropical lakes located in one of the most important coastal conservation areas, the Jurubatiba Sandbank National Park (Rio de Janeiro, Brazil). Rates of DCF were highly variable (means of 0.1-1.2 mmol C m(-2) d(-1)) among the studied lakes, with mostly production occurring below 10 mm of sediment in the anoxic zone. Although presenting a relatively low contribution in relation to BP and SOC, our study showed extensive microbial metabolism in the anaerobic sediment below the top centimeter, highlighting the importance of studying microbial processes across depth at fine scales. To our knowledge, it is the first study to show detailed vertical DCF rates in coastal tropical lake sediments, thus contributing to a better comprehension of the microbial role in the biogeochemical cycles of aquatic systems.

Ämnesord

NATURVETENSKAP  -- Geovetenskap och miljövetenskap -- Miljövetenskap (hsv//swe)

NATURAL SCIENCES  -- Earth and Related Environmental Sciences -- Environmental Sciences (hsv//eng)

NATURVETENSKAP  -- Biologi -- Ekologi (hsv//swe)

NATURAL SCIENCES  -- Biological Sciences -- Ecology (hsv//eng)

Nyckelord

Dark carbon fixation

Bacterial production

Shallow lakes

Oxic-anoxic foodweb

Tropical aquatic systems

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