枸杞岛厚壳贻贝养殖区浮游植物固碳潜力及去向研究

Study on Carbon Sequestration of Marine Phytoplankton in A Mussel Farm around Gouqi Island

贝类滤食会影响浮游植物碳的去向,而关于贝类养殖区浮游植物的固碳潜力及贝类摄食对浮游植物碳沉降的作用研究甚少。为此,本文基于枸杞岛贻贝养殖区表层和底层叶绿素a浓度的年际变化,分别估算了浮游植物的固碳潜力和沉降有机碳量,并结合厚壳贻贝内脏团干重的季节变化,分析了贻贝滤食对浮游植物碳沉降的影响。结果表明,该海域浮游植物的全年固碳量约为967.91 t。沉降有机碳占固碳总量的比例和贻贝内脏团干重呈显著负相关,表明贻贝滤食是影响浮游植物碳沉降的主要原因之一。通过对比陆地森林生态系统的固碳能力,该海域浮游植物的固碳效率是陆地森林生态系统的10.51~62.37倍,高效的初级生产力支撑了近海贝类的高密度养殖,也在近岸海洋碳循环中发挥了重要作用。

The raft culture shellfish may affect the cycle of organic carbon in marine phytoplankton.However,few studies have examined the effect of raft culture shellfish on carbon sequestration of phytoplankton and its transfer process.To this end,we examined the annual changes of chlorophyll a concentration and visceral mass dry weight of Mytilus coruscus in mussel farm around Gouqi island.The results showed that both chlorophyll a concentration and carbon fixation capacity of marine phytoplankton in the surface layer were highest in summer,followed by autumn,spring and winter.We found that the annual organic carbon production of phytoplankton in the surface area was 967.91 t.Among these,18.34%of organic carbon can be deposited to the bottom.And the ratio of bottom organic carbon to surface organic carbon was negatively correlated with the visceral mass dry weight of mussels,indicating that the seasonal differences in feeding rate of mussels could strongly affect the phytoplankton deposition.In addition,comparing with the carbon fixation capacity of terrestrial forest ecosystems,we found that the carbon fixation efficiency of phytoplankton around Gouqi island is 10.51-62.37 times than that of terrestrial forest ecosystems.Therefore,the phytoplankton in the area of suspended mussel culture may have played an important role in the global carbon cycle.