Mariculture increases microbially-driven carbon metabolism and sequestration in coastal ecosystems

Area of Science:

• Marine biology
• Microbial ecology
• Biogeochemistry

Background:

• Mariculture expansion is driven by seafood demand and ocean carbon sequestration.
• Microbial roles in sedimentary carbon sequestration within mariculture remain understudied.
• Understanding microbial mediation of organic carbon metabolism is crucial for coastal carbon budgets.

Purpose of the Study:

• To investigate the impact of mariculture on sedimentary carbon pools and microbial communities.
• To compare carbon fractions, contents, and extracellular hydrolase activities across different mariculture types and a control area.
• To identify microbial taxa and metabolic pathways involved in carbon sequestration and degradation.

Main Methods:

• Sediment sampling from macroalgae, fish/abalone culture areas, and a control site.
• Analysis of carbon fractions (TOC, SOC, DOC, ROC) and extracellular hydrolase activities.
• Microbial community profiling using 16S rRNA gene amplicon sequencing and metagenomics.

Main Results:

• Macroalgae culture areas showed significantly higher carbon sequestration potential compared to control areas.
• Increased total organic carbon (TOC), soil organic carbon (SOC), dissolved organic carbon (DOC), and refractory organic carbon (ROC) were observed in mariculture sediments.
• Reduced extracellular hydrolase activity and fewer carbon-degrading genes were found in macroalgae culture sediments.
• Key microbial taxa (e.g., Alteromonadaceae, Rhodobacteraceae) with flexible metabolic capabilities were identified.
• Increased total nitrogen (TN) and nitrate-nitrogen (NO3-) may enhance microbial organic carbon degradation, potentially reducing carbon stocks.

Conclusions:

• Macroalgae mariculture significantly enhances sedimentary carbon sequestration.
• Microbial communities and their metabolic activities are critical regulators of carbon cycling in mariculture ecosystems.
• Further research is needed to fully elucidate the complex interactions between mariculture practices, microbial functions, and coastal carbon sequestration.