Golden Apple Snail Activity Alters Greenhouse Gas Emissions and Microbial Communities in Paddy Soil

Animal activity plays an important role in regulating soil methane (CH4) and nitrous oxide (N2O) emissions. As a global invasive gastropod, golden apple snail (GAS, Pomacea canaliculata) has established great populations in wetlands, which has disturbed the soil ecological process. However, the impact of GAS activities on greenhouse gas (GHG) emissions is still unclear. A 25-day mesocosm experiment was conducted to examine CH4 and N2O fluxes, soil properties, microbial community, and GHG-related functional genes under low-density (GASL), high-density (GASH) and control (CK, without snail) treatments. Results showed that GASL significantly increased soil porosity and total nitrogen content by 18.6% and 7.6% on the 25th day. GASH significantly increased soil urease and sucrase activities by 18.1% and 30.0%. GASH significantly decreased the CH4 emission flux by 18.7% and increased the N2O emission flux by 33.1% on the 25th day. The 25-day cumulative CH4 and N2O emissions from female and male snail accounted for 0.002% and 2.3% of the total CH4 and N2O emissions in the GASH treatment, respectively. Moreover, GAS altered the soil microbial community composition. GASL significantly decreased the relative abundance of the phylum Chloroflexota by 11.3%, and increased the relative abundance of the family Nitrospiraceae by 24.5%. Compared with CK, GASH reduced the abundance of functional genes of mcrA, AOA-amoA, and nosZ by 16.9%, 19.7%, and 21.1%, respectively, while increasing the abundance of pmoA, AOB-amoA, and nirS by 18.4%, 65.3%, and 54.2%, respectively. These findings indicate that GAS disturbs soil physiochemical and microbial properties, and the conclusions are limited to a short-term mesocosm experiment.