陆源DON亲水和疏水组分对米氏凯伦藻和中肋骨条藻生长及种间竞争的影响

Effects of Hydrophilic and Hydrophobic Components of Terrigenous Dissolved Organic Nitrogen on the Growth and Interspecific Competition of Karenia mikimotoi and Skeletonema costatum

本文以米氏凯伦藻(Karenia mikimotoi)和中肋骨条藻(Skeletonema costatum)为研究对象,采用畜禽养殖源有机质为DON氮源,应用XAD-8树脂分离亲水性和疏水性组分,并进行单一藻和双藻混合DON加富室内受控培养实验。结果表明,亲水性DON组分和疏水性DON组分均可促进米氏凯伦藻和中肋骨条藻的生长,其中,亲水组分的促进作用优于疏水组分(P<0.05,α=0.05)。在溶解无机氮浓度不受限条件下,通过DON加富培养,中肋骨条藻相对于米氏凯伦藻具有竞争优势,表现为氮营养盐吸收速率常数、氮亲和力指数和浮游植物生长速率常数均大于米氏凯伦藻(P<0.05,α=0.05),这可能与米氏凯伦藻在吸收利用DON过程中,需要分泌更多的亮氨酸氨肽酶以提高其营养供应策略有关,而中肋骨条藻则可以在较低的酶活性下吸收利用不同形态和组成的氮。本文研究结果有助于从动力学上加深不同DON组分对长江口赤潮多发区中肋骨条藻赤潮爆发支撑作用的理解。

In recent years, red tide of Karenia mikimotoi and Skeletonema costatum occur frequently in coastal areas of China, causing huge ecological and economic losses. Dissolved organic nitrogen has a potential impact on the occurrence of these two types of red tides, due to the complexity of the structure and composition of dissolved organic nitrogen, knowledge of the bioavailable composition of dissolved organic nitrogen is still very limited. Therefore, in this study, K. mikimotoi and S. costatum were taken as the research objects, the organic matter from livestock and poultry breeding was taken as DON, and the hydrophilic and hydrophobic components were speparated by XAD-8 resin, and the laboratory controlled culture of single algae and mixed algae was carried out. The results showed that both the hydrophilic DON component and the hydrophobic DON component promoted the growth of K. mikimotoi and S. costatum, and the hydrophilic DON component promoted the growth of K. mikimotoi and S. costatum significantly better than the hydrophobic DON component(p<0.05). Under the condition that concentration of dissolved inorganic is not limited, through DON enrichment culture experiment, S. costatum has a significant competitive advantage over K. mikimotoi, which is shown as nitrogen nutrient absorption rate constant, nitrogen affinity index and phytoplankton growth rate constant are significantly higher than K. mikimotoi(p<0.05, α=0.05). This may be related to the fact that K. mikimotoi needs to secrete more lecucine aminopeptidase to improve its nutrient supply strategy during the absorption and utilization of DON, while S. costatum can absorb and utilize nitrogen with different forms and compositions under lower enzyme activity. From the perspective of dynamics, the results of this study can deepen the understanding of the supporting effect of different DON components on S. costatum outburst in the red tide frequent area of the Yangtze Estuary.