This study examined bacterial biomass and production, and Organic Carbon changes over short-term (12 days) dark incubations with added Total Organic Carbon (TOC) or Dissolved Organic Carbon (DOC). At three sites along the middle stretch of the GBR during the dry and wet seasons

Water samples for the laboratory incubation experiments collected at 5 m depth, during the late dry (September 2014), wet (February 2015) and early dry (June 2015) seasons at Russel Island, Tully transect and Pandora reef. Salinity and temperature were recorded in situ using a conductivity-temperature-depth (CTD) probe (Seabird SBE 37 plus). Water samples for the Particulate And Dissolved Nutrient Data (MMP) for laboratory analysis was also collected.

Incubation experiments:

From the initial 100 L of seawater collected in the Great Barrier Reef (Australia), 50 L were 0.2 µm filtered to obtain the POC filtrite, 5 L were 1.2 µm filtered to obtain the microbial culture, and the remaining 45 L were dual-stage filtered (0.8–0.2 µm) to obtain the DOC filtrate. The TOC incubations were assembled by combining the POC filtrite with 2.5 L of the microbial culture, and 20 L of the DOC filtrate; the DOC incubations were assembled by combining 2.5 L of the microbial culture with 20 L of the DOC filtrate. Finally, 20 bottles were filled with 0.5 L of the TOC mixture and 20 bottles with the DOC mixture

This study aimed to understand the differences in OC cycling (OC uptake by bacteria and use for either Bacterial Productivity or Bacterial Respiration) between total (TOC) and dissolved (DOC) fractions.

For further informaiton see Carreira et al. (2021).