期刊
BIOGEOCHEMISTRY
卷 154, 期 3, 页码 489-508出版社
SPRINGER
DOI: 10.1007/s10533-021-00802-x
关键词
Great Barrier Reef; Dissolved organic carbon; Total organic carbon; Heterotrophic bacteria; Tropical coastal waters; Organic carbon cycling
资金
- Australian Institute of Marine Science
- Great Barrier Reef Marine Park Authority
- Australian Government Reef Program
- FCT/MCTES [UIDP/50017/2020+UIDB/50017/2020]
- Fundacao para a Ciencia e a Tecnologia (FCT) [SFRH/BPD/117746/2016]
- Fundação para a Ciência e a Tecnologia [SFRH/BPD/117746/2016] Funding Source: FCT
This study conducted short-term experiments in tropical coastal waters and found that bacterial growth efficiency is low, and there is no difference in carbon cycling between different sources, seasons, or locations. Overall, the study suggests that the Great Barrier Reef is a heterotrophic system.
Heterotrophic bacteria typically take up directly dissolved organic matter due to the small molecular size, although both particulate and dissolved organic matter have labile (easily consumed) compounds. Tropical coastal waters are important ecosystems because of their high productivity. However, few studies have determined bacterial cycling (i.e. carbon uptake by bacteria and allocation for bacterial biomass and respiration) of dissolved organic carbon in coastal tropical waters, and none has determined bacterial cycling of total and dissolved organic carbon simultaneously. In this study we followed bacterial biomass and production, and organic carbon changes over short-term (12 days) dark incubations with (total organic carbon, TOC) and without particulate organic carbon additions (dissolved organic carbon, DOC). The study was performed at three sites along the middle stretch of the Great Barrier Reef (GBR) during the dry and wet seasons. Our results show that the bacterial growth efficiency is low (0.1-11.5%) compared to other coastal tropical systems, and there were no differences in the carbon cycling between organic matter sources, seasons or locations. Nonetheless, more carbon was consumed in the TOC compared to the DOC incubations, although the proportion allocated to biomass and respiration was similar. This suggests that having more bioavailable substrate in the particulate form did not benefit bacteria. Overall, our study indicates that when comparing the obtained respiration rates with previously measured primary production rates, the GBR is a heterotrophic system. More detailed studies are required to fully explore the mechanisms used by bacteria to cycle TOC and DOC in tropical coastal waters.
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