大亚湾夏季浮游群落生产代谢特征及其影响因素*

2017年8月对大亚湾海域浮游群落初级生产、群落呼吸代谢及其平衡特征进行了研究, 并分析了其潜在环境影响因素以及对沿岸生态系统功能与健康的指示作用。研究结果表明, 大亚湾夏季海水表层呈自养状态, 而底层呈异养状态, 群落总初级生产力(gross primary productivity, GPP)、呼吸代谢速率(community respiration, CR)与净生产力(net commutnitiy production, NCP)在表层分别为1335.36±910.12、597.86±403.30和737.50±608.22mg C·m^-3·d^-1; 在底层分别为43.65±37.05、216.25±147.28和-160.27±137.01mg C·m^-3·d^-1。海湾整体呈自养状态, 水柱平均NCP为233.41±248.88mg C·m^-3·d^-1; 部分沿岸水域存在异养状态。1~200μm粒级浮游生物是GPP和CR的主要贡献者。相关性分析和主成分分析显示, NCP在表层受GPP和CR共同调控, 且与浮游植物生物量和营养盐正相关; 而在底层主要受CR影响, 且与盐度正相关。大亚湾夏季群落生产代谢平衡存在明显的水平和垂向变化, NCP的区域差异与潜在波动性对该海湾生态系统稳定性及健康状况有重要的指示作用。

Production and metabolism characteristics of planktonic community and their influencing factors in Daya Bay during summer*

In August 2017, the primary production, community respiration and their metabolic balance status of the planktonic community in Daya Bay were studied, and the potential environmental impact factors and their indicator effects on the function and health of the offshore ecosystem were analyzed. Our results showed that Daya Bay was autotrophic in surface water but heterotrophic in the bottom layer. The gross primary productivity (GPP), community respiration (CR) and net community production (NCP) were 1335±910.12, 597.86±403.30 and 737.50±608.22 mg C·m^-3·d^-1 in surface water and 43.65±37.05, 216.25±147.28 and -160.27±137.01 mg C·m^-3·d^-1 in the bottom, respectively. Overall, Daya Bay was autotrophic with an average NCP of 233.41±248.88 mg C·m^-3·d^-1 in the water column. Size-fractioned result of plankton community metabolism showed that plankton with the cell size of 1-200 μm was the main contributor to GPP and CR in surface water. Correlation analysis and principal component analysis showed that NCP was jointly regulated by GPP and CR in surface water and was positively correlated with phytoplankton biomass as well as nutrient concentration; in the bottom, it was mainly affected by CR and was positively correlated with salinity. The planktonic metabolism balance in Daya Bay during summer varied horizontally and vertically. The regional differences and potential fluctuations of NCP are important indicators of ecosystem stability and health in the bay.