淡水中型浮游动物群体与悬浮物碳氮磷比耦联研究

INVESTIGATING THE STOICHIOMETRIC COUPLING BETWEEN MESOZOOPLANKTON ASSEMBLAGE AND SESTON IN FRESHWATERS

通过对湖北省13个湖库悬浮物和中型浮游动物群体碳氮磷比的分析,探讨了浮游动物与食物之间的元素耦联和不平衡性是如何随食物质量的改变而变化,以及这种不平衡性对生态系统浮游动植物间能量传递效率的影响。结果显示:中型浮游动物C﹕N比和C﹕P比分别随悬浮物C﹕N比和C﹕P比的增加而变大。悬浮物-中型浮游动物之间的元素不平衡性不仅与悬浮物C﹕N比显著正相关(r=0.97,P<0.001),且与悬浮物C﹕P比也显著正相关(r=0.81,P=0.001)。浮游动植物之间的能量传递效率与悬浮物-中型浮游动物C﹕P比差值呈显著负相关(r=–0.58,P=0.037),但与其C﹕N比差值关系不显著(P>0.05)。此外,中型浮游动物生物量也随其与悬浮物之间C﹕P比差值的增大而下降(r=–0.59,P=0.033)。这些结果表明,悬浮物碳氮磷比能显著影响中型浮游动物群体的碳氮磷比组成,两者之间的元素不平衡性随前者的增加而变大并进而降低能量向后者的传递。

Food quality can significantly affect the phosphorus content,growth,reproduction,as well as physiological behavior of zooplankton,leading to regulate the energy transfer efficiency at the primary producer-consumer interface.However,the elemental coupling between zooplankton and food is scarcely observed at the community level.In this study,the elemental coupling and the elemental imbalances between seston and mesozooplankton assemblage in addition to the ecological impacts of such imbalances on zooplankton-phytoplankton interaction were detailed by analyzing the compositions of carbon,nitrogen,and phosphorus in seston and mesozooplankton assemblage derived from 13 samples containing water bodies in the Hubei province,China.The achieved results showed that both C﹕N and C﹕P ratios in mesozooplankton were positively correlated with the corresponding ratios in seston.Besides,the elemental imbalances between seston and mesozooplankton were positively correlated with the corresponding seston ratio(C﹕N,r=0.97,P<0.001;C﹕P,r=0.81,P=0.001).Further analysis also revealed that the energy transfer efficiency between zooplankton and phytoplankton declined with the increase of elemental imbalance in C﹕P ratio(r=–0.58,P=0.037).Moreover,a similar decline in zooplankton biomass was found as well as increase of imbalance in C﹕P ratio(r=–0.59,P=0.033).These results indicated that seston stoichiometry could remarkably impact the elemental stoichiometry of mesozooplankton assemblage,and the elemental imbalances tended to be greater with the increase of seston stoichiometry;consequently,the energy transferred to mesozooplankton was decreased as well.