陆源有机碳对莱州湾浮游动物能量贡献的初步研究

A preliminary study on energy contribution of terrestrial organic carbon to zooplankton in the Laizhou Bay

研究了莱州湾浮游动物及其潜在能量来源颗粒有机碳与溶解有机碳的稳定同位素特征,发现颗粒有机碳、溶解有机碳以及浮游动物碳稳定同位素分别为(-23.24±0.52)‰、(-22.93±0.59)‰、(-21.63±0.76)‰。陆源有机碳在颗粒有机碳库、溶解有机碳碳库中的相对含量分别为(58.2±5.7)%、(54.8±6.6)%,均超过海源有机碳相对含量。陆源有机碳对浮游动物能量贡献为(45.2±8.5)%,略低于海源有机碳贡献。海源有机碳在浮游动物体内更为"富集",浮游动物更倾向于利用海源有机碳。陆源有机碳作为补充碳源,为浮游动物提供了额外能量。

Estuary and coast link the terrestrial and marine organic carbon pools. Global rivers transported 0.40 GT of terrestrial organic carbon to the oceans each year. The fluxes of riverine discharged terrestrial organic carbon can sustain the ocean organic carbon cycles. However, stable isotope and biomarker evidence indicated that terrestrial organic carbon only accounted for a small part of marine organic pools. It seems that only a fraction of terrestrial organic carbon enters into the ocean. It entered into the material cycles and energy flows of estuary and coast. Zooplankton was the secondary producer in the ecosystem,which provided the material and energy for the high trophic level organisms. By the study of the support of terrestrial organic carbon for zooplankton,it will help to know the energy contribution of terrestrial organic carbon to the system.A quantity of terrestrial organic carbon was transported into the Laizhou Bay each year. The Yellow River which enters into the ocean in the Laizhou Bay,which transports 2. 12 × 10^5 t particulate terrestrial organic carbon and 6. 43 × 10^4 t dissolved terrestrial organic carbon into the bay. The richness of fishery source in the bay may be related to the fluxes of terrestrial organic carbon. To study the energy contribution of terrestrial organic carbon to the zooplankton in the bay,the carbon stable isotope of zooplankton and particulate organic carbon,dissolved organic carbon was analyzed in 21 stations. In this study,the δ^13C of particulate organic carbon,dissolved organic carbon and zooplankton was（-23. 24 ± 0. 52） ‰,（-22. 93 ± 0. 59） ‰ and（-21. 63 ± 0. 76） ‰ respectively. By the two end-mumber mixing model basing of conservation of mass,the content of terrestrial organic carbon in the particulate organic carbon and dissolved organic carbon pool was calculated. In this study,the terrestrial organic carbon in the particulate organic carbon and dissolved organic carbon pool was（ 8. 2 ± 5. 7%）,（ 54. 8 ± 6. 6） % respectively,which exceeded the marine source organic carbon in the pools. The energy contribution of terrestrial organic carbon to zooplankton also was calculated by the mixing model. We found that the energy contribution of terrestrial organic carbon to zooplankton reached（ 45. 2 ± 8. 5） %,lower than the contribution of marine organic carbon. It seemed that marine organic carbon was richer in the zooplankton. And zooplankton preferred the marine organic carbon to the terrestrial organic carbon. Terrestrial organic carbon supplied additional energy for the zooplankton in the bay.