Bacterial carbon sources in coastal sediments: a cross-system analysis based on stable isotope data of biomarkers

摘要: Coastal ecosystems are typically highly produc- tive, and the sediments in these systems receive organic mat- ter from a variety of local imported sources. To as- sess if general patterns present origin carbon sources for sedimentary bacteria their relation to sediment pool, we compiled both literature new data on 13 C bacterial biomark- ers (the phospholipid derived fatty acids i+a15:0), along with ( CTOC) macro- phyte biomass typical near-coastal systems. These included mangroves, salt marshes (both C3 C4-dominated sites), seagrass beds, macroalgae- based systems, as well unvegetated sediments. First, our Ci+a15:0 showed large variability over en- tire range CTOC, indicating that many settings, bac- teria may depend various origins. Secondly, where macrophyte production is major supplier situ decomposi- tion generally limited carbon-rich, peaty sites (TOC>10 wt%), which likely make up only small part global area vegetated coastal carbon-rich also provided field estimate isotopic fractionation between biomarkers 3.7±2.1‰), similar ex- pected value about 3‰ associated biosynthesis acids. Thirdly, low TOC (be- 1 consistently found were selec- tively utilizing an isotopically enriched source, be root exudates but more micro- phytobenthos. In other 10 wt% TOC, appear show average little selectivity follow even sys-