大亚湾大型底栖动物近30年次级生产力变化特征

摘要

利用1988年1月和7月,2004年3月、5月、9月和12月,2008年3月、5月、9月和12月以及2015年2月、8月、11月和12月在大亚湾海域开展的共计14航次、200站次的大型底栖动物调查结果,根据Brey经验公式计算大型底栖动物次级生产力和次级生产力与生物量的比值(P/B值),分析近30年次级生产力变化特征.结果表明:1)以去灰干质量(ash free dry mass, AFDM)计,大亚湾4个时段大型底栖动物次级生产力分别为7.44 g·(m2·a)–1、11.34 g·(m2·a)–1、4.91 g·(m2·a)–1和2.93 g·(m2·a)–1,P/B值分别为0.76 a–1、0.86 a–1、0.79 a–1和0.47 a–1,均呈1988—2004年升高、2004—2015年降低的趋势.2)各类群次级生产力和P/B值变化趋势存在一定差异.其中软体动物、多毛类、甲壳类次级生产力和P/B值呈1988—2004年升高、2004年后降低的趋势;棘皮动物则均呈持续降低的趋势.3)综合各类群次级生产力平面分布图,湾顶西北部和大鹏澳附近海域变化明显.相关性分析显示,底栖动物次级生产力与海水无机氮、磷酸盐、溶解氧浓度和沉积物有机碳含量显著相关.%Based on the survey data collected from 200 sampling stations by 14 cruises in Daya Bay of the South China Sea in 1988, 2004, 2008 and 2015, we analyzed the characteristics of the secondary productivity and P/B (secondary production/biomass) ratio of macrobenthos for nearly 30 years using Brey's empirical formula. The results show that: 1) Based on ash free dry mass (AFDM), the microbenthic secondary productivity and P/B ratio were 7.44 g·(m2·a)–1and 0.76 a–1in 1988, 11.34 g·(m2·a)–1and 0.86 a–1in 2004, 4.91 g·(m2·a)–1and 0.79 a–1in 2008, 2.93 g·(m2·a)–1and 0.47 a–1in 2015, respectively. The secondary productivity and the P/B ratio of macrobenthos increased during 1988?2004, then decreased during 2004?2015. 2) The secondary productivity and the P/B ratio of the main groups of macrobenthos in Daya Bay differed significantly. The variation of secondary productivity and P/B ratio of Mol-lusca, Polychaeta and Crustacean increased during 1988?2004, then decreased during 2004?2015, being consistent with the trend of the whole macrobenthos in Daya Bay. Different from the other groups, the secondary productivity and P/B ratio of Echinoderm showed a decreasing trend during 1988?2015. 3) Generally, the secondary productivity of the macrobenthos had obvious variation in the northwest of the top Daya Bay and Dapeng'ao Bay. The correlation analysis between macrobenthos community and environment-al factors indicates that the secondary productivity was significantly affected by the contents of inorganic nitrogen, phosphorus, dis-solved oxygen of seawater and organic carbon content of sediment.