Conversion of earthen aquaculture ponds to integrated mangrove-aquaculture systems significantly reduced the emissions of CH 4 and N 2 O ☆ Zhinan Su a , Guanglong Qiu a , Ping Yang a,b,* , Hong Yang c , Wenjing Liu b , Lishan Tan d , Linhai Zhang b , Dongyao Sun e,* , Jiafang Huang b , Kam W. Tang f,* a Guangxi Key Lab of Mangrove Conservation and Utilization, Guangxi Mangrove Research Center, Guangxi Academy of Sciences, Beihai 536000 Guangxi, China b School of Geographical Sciences, Fujian Normal University, Fuzhou 350117, China c Department of Geography and Environmental Science, University of Reading, Reading RG6 6AB, UK d Department of Geography and Resource Management, The Chinese University of Hong Kong, Hong Kong, China e School of Geography Science and Geomatics Engineering, Suzhou University of Science and Technology, Suzhou 215009, China f Department of Life Sciences, Texas A&M University-Corpus Christi, TX 78412, USA A R T I C L E INFO Keywords: Methane (CH 4 ) Nitrous oxide (N 2 O) Earthen aquaculture ponds Integrated aquaculture systems Wetland restoration ABSTRACT Mangrove ecosystem helps mitigate regional and global climate change, but increasing land reclamation for aquaculture has degraded many mangroves wetlands. Integrated mangrove wetland-aquaculture systems can be a promising way to support both mangrove restoration and aquaculture, but its impacts on greenhouse gas emissions remain largely unknown. In this study, we compared CH 4 and N 2 O fluxes between earthen aquaculture ponds (EAPs) and integrated mangrove-aquaculture systems (IMASs) in Beibu Gulf in southern China. Results showed that both EAPs and IMASs were CH 4 and N 2 O emission sources with strong temporal variabilities. CH 4 fluxes were primarily affected by total organic carbon, dissolved oxygen and salinity. These fluxes were signif- icantly larger in EAPs (976.3 ± 146.4µg m -2 h  1 ) than in IMASs (60.3 ± 7.7µg m -2 h  1 ). Ebullition was respon- sible for 52.9–93.4 % of the total CH 4 emission. The average N 2 O flux in EAPs (3.4 ± 0.5µg m -2 h  1 ) was 5.7 times higher than IMASs during the farming period and was mainly driven by nitrogenous substrate availability. The results highlight that integrated mangrove wetland-aquaculture systems can not only promote mangrove restoration and support aquaculture, but also mitigate greenhouse gases emissions from coastal wetlands. 1. Introduction Coastal wetlands are among the most productive yet vulnerable ecosystems (Barbier et al., 2011; Breda et al., 2022; Costanza et al., 1997; Liu and Ma, 2024). Despite covering just 0.3 % of the ocean’s surface, coastal wetlands provide essential ecosystem services such as shoreline protection, biodiversity maintenance, water purification, supporting fisheries and food provision (Alongi, 2008; Barbier et al., 2011; Nguyen et al., 2022; de Groot et al., 2012). Coastal wetlands play an important role in mitigating climate change because of their sub- stantial capacity to absorb and store atmospheric CO 2 (Duarte et al., 2013; Lai et al., 2016; Macreadie et al., 2019; Song et al., 2023). However, many coastal wetlands have been lost or degraded due to land conversion, pollution and climate change (Fluet-Chouinard et al., 2023; Sasmito et al., 2019; Serrano et al., 2019; Spivak et al., 2019), severely compromising essential ecosystem functions. Mangrove wetlands are widely distributed along tropical and sub- tropical coastlines (Lee et al., 2014; Liu and Chui, 2022; Wang et al., 2024). As a way to increase food security, promote rural economy and create jobs, many mangroves have been transformed into earthen aquaculture ponds (B´en´e et al., 2016; Nguyen et al., 2022; FAO, 2022), particularly in the Asia-Pacific areas (Nguyen et al., 2022; Richards and Friess, 2016; Zhang et al., 2022a) and mainland China (Fan et al., 2023; Gou et al., 2024; Ren et al., 2019). Over the last century, more than 60 % ☆ This article is part of a special issue entitled: ‘Water-Carbon processes’ published in Journal of Hydrology. * Corresponding authors at: Guangxi Key Lab of Mangrove Conservation and Utilization, Guangxi Mangrove Research Center, Guangxi Academy of Sciences, Beihai 536000, Guangxi, China (P. Yang). E-mail addresses: yangping528@sina.cn (P. Yang), dongyaos@126.com (D. Sun), kamwing.tang@tamucc.edu (K.W. Tang). Contents lists available at ScienceDirect Journal of Hydrology journal homepage: www.elsevier.com/locate/jhydrol https://doi.org/10.1016/j.jhydrol.2025.132692 Journal of Hydrology 652 (2025) 132692 Available online 13 January 2025 0022-1694/© 2025 Elsevier B.V. All rights are reserved, including those for text and data mining, AI training, and similar technologies.