Role of benthic fauna in the decomposition of Sargassum fusiforme litter

Abstract

To explore the contribution of benthic fauna to mass loss during the decomposition of Sargassum fusiforme litter and their role in influencing chemical composition changes, a 48-day field decomposition experiment was conducted on S. fusiforme litter collected from Gouqi Island, East China Sea. Three types of mesh bags with different mesh size (2, 0.5, and 0.01 mm) were used to analyze the mass loss and chemical composition changes of the litter and their relationship with benthic fauna communities. The results indicated that benthic fauna contributed 14.83%–16.69% of the mass loss of S. fusiforme litter. Furthermore, benthic fauna facilitated the reduction of biochemical substances such as carbon, phosphorus, cellulose, and hemicellulose in the litter. A significant negative correlation was found between the number of taxonomic classes and the carbon and phosphorus content (p < 0.05), while the abundance of benthic fauna showed a significant negative correlation with carbon, phosphorus, lignin, cellulose, and hemicellulose content (p < 0.05). The number of taxonomic classes and abundance in the 2 mm mesh bags were also greater than those in the 0.5 mm bags. In conclusion, benthic fauna played a promotive role in the decomposition process of S. fusiforme litter, providing valuable insights into the natural decomposition mechanisms of large seaweed.