Carbon Sequestration by Shellfish in Yantai's Coastal Waters

Abstract

The carbon sequestration by shellfish constitutes a significant component of marine carbon sinks. This study quantitatively analyzed their carbon sequestration potential by measuring the carbon content of cultivated Zhikong scallops (Chlamys farreri) and bay scallops (Argopecten irradians) from the coastal aquaculture areas of Yangma Island, Yantai, as well as wild blood clams (Scapharca broughtonii) and mirror clams (Amusium pleuronectes) from Tianyue Bay. Specimens were collected during April and November 2024 to assess seasonal variations in carbon fixation efficiency.The results demonstrated species-specific carbon allocation patterns: the shell carbon content ranged from 12.55% to 13.51% in bay scallops (Argopecten irradians), 12.36% to 12.64% in Zhikong scallops (Chlamys farreri), and 12.01% to 13.52% in blood clams (Scapharca broughtonii), with minimal seasonal differences (April vs. November) observed in these three species, indicating temporal stability. In contrast, mirror clams (Amusium pleuronectes) exhibited a significant seasonal increase in shell carbon content, rising from 11.82%~11.94% in April to 12.51%~12.64% in November (p < 0.05). Soft tissues consistently displayed significantly higher carbon content than shells across all species (p < 0.01); however, this disparity diminished with increasing individual size, showing no significant differences in larger specimens. Seasonal variations in CO₂sequestration rates were most pronounced in mirror clams, with absorption values increasing from 14.20~22.39 g•a^-1 in April to 23.36~41.73 g•a^-1 in November, where larger individuals exhibited amplified differences (r = 0.82, p < 0.001). Economic analysis revealed that Yantai’s mariculture shellfish harvest in 2022 reduced CO₂mitigation costs by approximately 71.64 million yuan (equivalent to~10.12 million USD), highlighting the triple benefits of bivalve aquaculture in fostering social welfare, economic profitability, and ecological resilience through enhanced carbon sink services.