Carbon dioxide and methane fluxes across the sediment-water interface in different grass carp Ctenopharyngodon idella polyculture models

Abstract

Benthic fluxes of carbon dioxide (CO 2 ) and methane (CH 4 ) were evaluated in grass carp Ctenopharyngodon idella (G), silver carp Hypophthalmichthys molitrix (S), and bighead carp Aristichthys nobilis (B) polyculture systems, to which topmouth culter Erythroculter ilishaeformis (T), Pacific white shrimp Litopenaeus vannamei (P), or common carp Cyprinus carpio (C) were added. These systems, GSBT, GSBP, and GSBC, respectively, were monitored over 5 mo (May to September 2014). The presence of L. vannamei and C. carpio increased CO 2 and CH 4 emissions in GSBP and GSBC, respectively. From June to August, CO 2 and CH 4 fluxes increased in the 3 systems, and in July and August these fluxes were significantly higher in GSBC than in GSBP and GSBT, and significantly higher in GSBP than in GSBT. The metabolisms of L. vannamei and C. carpio contributed to decrease dissolved oxygen, pH, and oxidation−reduction levels, and the bioturbation of the upper sediment layers caused by these species increased organic matter degradation rate, resulting in a significant increase in particulate and dissolved organic carbon in the overlying water. Our results indicate that improving feeding efficiency and reducing organic carbon accumulation on the bottom of aquaculture ponds, as well as increasing dissolved oxygen and decreasing bioturbation across the sediment−water interface during farming seasons, is likely to reduce CO 2 and CH 4 release from aquaculture pond sediment, especially in July and August.

Benthivorous fish bioturbation reduces methane emissions, but increases total greenhouse gas emissions

“…Limitation of algal growth due to fish‐enhanced turbidity is also a common phenomenon in aquacultures (Rahman et al., ). Other studies found fish‐induced increases in water column CO 2 concentration as well (Rahman et al., ; Xiong et al., ). In hypertrophic fish cultures, however, the CO 2 emissions tend to be much higher than those we found in our study (Chen et al., ).…”

“…We found that in our systems, where water column O 2 concentrations remained above 3 mg/L during the entire study period, fish strongly reduced CH 4 emissions, contrasting other studies reporting high CH 4 emission rates for fish ponds (Datta et al., ; Frei et al., ), which the authors attribute to fish‐induced lowering of surface water O 2 concentrations (Xiong, Wang, Guo, Liu, & Dong, ). These low O 2 concentration may be caused by fish respiration, reduced phytoplanktonic photosynthesis due to high turbidity, or enhanced aerobic organic matter oxidation due to bioturbation.…”

Diffusive methane emissions from temperate semi-intensive carp ponds

“…The peak of CH 4 flux recorded in the main ponds in May can be explained by sediment bioturbation by carp along with wind speed. At the beginning of the growing season, the feeding behaviour of carp enhances the release of CH 4 accumulated in sediment during the previous growing season and winter (Bhattacharyya et al 2013, Xiong et al 2017. The average wind speed in May was higher over the main ponds (2.3 ± 0.5 m s −1 ) than above nursery ponds (1.0 ± 0.5 m s −1 ).…”

“…In some countries, fishponds are an important component of lentic ecosystems (Pechar 2000). Fishponds occupy a surface area of 1200 km 2 in France, 410 km 2 in the Czech Republic, 420 km 2 in Germany, 25 669 km 2 in China, and 87 500 km 2 worldwide (Pokorný & Hauser 2002, Four et al 2017, Xiong et al 2017). In addition to rearing fish, fishponds provide ecosystem functions such as flood regulation along with retention of water, sediments, organic matter, nutrients, and micropollutants and may be important in maintaining bio diversity (Oertli et al 2005, Boyd et al 2010, Gaillard et al 2016.…”

Methane Dynamics of Aquaculture Shrimp Ponds in Two Subtropical Estuaries, Southeast China: Dissolved Concentration, Net Sediment Release, and Water Oxidation

“…Therefore, the boundary between the water column and sediments, i.e. the sediment‐water interface (SWI), plays a critical role in the production, transfer, circulation, and storage of CH 4 in aquaculture ponds (Xiong et al, ). While the rapid development of the aquaculture industry has stimulated researches examining CH 4 biogeochemistry in aquaculture systems, most of the previous studies only focused on CH 4 exchange across the water‐air interface and its influencing factors (e.g., Chen et al, ; Hu et al, , ; Yang et al, ; Yang, Bastviken, et al, ; P. Yang et al, ).…”