Paddy periphyton: Potential roles for salt and nutrient management in degraded mudflats from coastal reclamation

Periphyton exists ubiquitously in paddy ecosystems of coastal mudflat area, playing significant roles in salt and nutrient cycling between the water and soil interface. However, the definition, composition, influenced factors, and potential function of paddy periphyton are still unclear. We attempt to define paddy periphyton as an integrated and independent microcosm, which is dominated by phototrophic communities, containing both biotic components, such as algal, fungal, bacterial, protozoan, and metazoan, and abiotic components, such as soil, extracellular polymeric substance, and detritus. They interact with each other such as predation and competition, co‐inhabiting in a common microhabitat. The development of paddy periphyton mainly includes three processes: growth stage, mature stage, and fading stage. Paddy periphyton has a significant influence on the salt migration in paddy ecosystem that was reclaimed from coastal mudflat by improving the soil structure, assimilating and adsorbing the salt like sodium chloride, and inhibiting the salt accumulation near the soil surface. As for nutrient management, the roles of paddy periphyton can be summarized as a slow‐released bio‐fertilizer, a nutrient‐removal agent, a nutrient mediator, and a nutrient indicator in mudflat‐reclaimed paddy ecosystem. All these imply that paddy periphyton may be a new and promising biotechnological tool for better salt and nutrient management in paddy ecosystems that degraded from mudflat land, which has a vast potential in the amelioration and fertility improvement of salt‐affected soils, as well as control of nonpoint agricultural pollution in coastal areas.