Aquaculture ponds show promise in climate fight: greenhouse conditions boost carbon capture and fish breeding

Aquaculture's Role in Carbon Mitigation

Climate change and greenhouse gas (GHG) emissions pose a critical global challenge, with agriculture contributing a significant portion. While aquaculture ponds are known to contribute to GHG emissions, their potential as carbon sinks remains largely underestimated. Enhancing natural carbon storage, or biosequestration, in ecosystems is crucial for managing rising atmospheric carbon dioxide levels. This study explores a novel approach to turn aquaculture into a more sustainable and climate-resilient practice.

Novel Approach to Carbon Reduction

Researchers investigated the synergistic effects of increased temperature (mimicking greenhouse conditions) and various manure treatments on carbon reduction potential in aquaculture pond sediments. Using 36 mesocosms, half placed inside a polyhouse and half outside, they applied different organic manures—cattle manure, poultry droppings, vermi-compost, and a mixed combination—to examine their impact on soil organic carbon, carbon burial rates, algal productivity, and even tilapia breeding responses.

Significant Carbon Capture Gains

The findings are striking: the greenhouse-mimicking conditions, which resulted in an average 6°C rise in atmospheric temperature, significantly enhanced the carbon reduction potential in the aquaculture sediments by 44.36% to 62.36%. This led to an impressive 27.90% increase in average carbon burial rates compared to ambient temperatures. The study demonstrated a direct correlation between higher soil organic carbon content (38.16-56.40 mg C/g) and increased carbon burial.

Understanding the Mechanism

The elevated temperature inside the polyhouse proved to be a key driver. It accelerated the decomposition of applied manures, boosting microbial activity and consequently enhancing the primary productivity of microalgae. This increased biomass, along with organic particles, detritus, and fish excrements, settled into the sediment, contributing to a greater "carbon sink" or long-term sequestration of atmospheric carbon dioxide. On average, residual carbon in soils increased by 23% due to the GHG-mediated temperature rise.

Unexpected Benefits for Fish Breeding

Beyond carbon sequestration, the study revealed another remarkable advantage: the simulated greenhouse conditions, combined with specific manure treatments, successfully induced tilapia (Oreochromis niloticus) to breed during winter. In one treatment using vermi-compost, 100% fish survival was observed, contrasting with significant mortality in open conditions. This suggests that the combined effects of manure-driven water quality, food resources, and elevated temperatures created an optimal environment for fish reproduction, even in colder months.

Practical Implications for Sustainable Aquaculture

The research quantifies a crucial relationship: for every one-degree Celsius rise in atmospheric temperature, there was approximately a 4% increase in residual carbon in the experimental tanks. This highlights the potential for small impoundments under intensive farming and manuring to act as substantial carbon sinks. The mixed manure treatment consistently showed the highest carbon reduction potential, suggesting an optimal strategy for maximizing environmental benefits.

Towards a Low Carbon Footprint Future

This pioneering mesocosm study is among the first to directly address the carbon accumulation potential of aquaculture systems under increasing CO₂ concentrations and enhanced temperatures with nutrient fertilization. By demonstrating the effectiveness of manure-driven, ecosystem-functional culture practices in enhancing primary productivity, food chains, and fish biomass while simultaneously sequestering carbon, this research offers a valuable pathway toward developing more sustainable aquaculture practices with a significantly reduced carbon footprint.

Corresponding Author:
 

Deblina Dutta, Debajyoti Kundu

Original Source:
 

https://doi.org/10.1007/s44246-022-00018-0

Contributions:
 

Deblina Dutta: Data curation, Formal analysis, Investigation, Validation, Writing – original draft; Debajyoti Kundu: Data curation, Formal analysis, Investigation, Validation, Writing – original draft, Writing – review & editing; Bana Bihari Jana: Writing – original draft, Conceptualization, Funding acquisition, Project administration, Supervision, Resources; Susmita Lahiri: Writing – review & editing; Jatindra Nath Bhakta: Writing – review & editing. All authors reviewed the results and approved the final version of the manuscript.