半连续培养下东海原甲藻和中肋骨条藻种群生长过程与种间竞争研究

采用半连续培养方法研究了温度和营养盐(N和P)限制对中国东海2种重要赤潮生物东海原甲藻和中肋骨条藻生长及种间竞争的影响。结果表明,东海原甲藻在20℃和25℃时生长状态良好,具有明显的指数增长期,15℃时细胞生长明显受到影响;中肋骨条藻具有较广的温度适应性,15~25℃时均具有明显的指数增长期。东海原甲藻可以忍受低营养盐环境并种群增长,而中肋骨条藻细胞增长需要较丰富的营养盐。在营养盐充足的环境里中肋骨条藻具有竞争优势,相反,在营养盐限制的环境中,东海原甲藻是竞争的优胜者。实验结果与东海原甲藻赤潮爆发现场的环境调查结果基本一致,可以作为解释东海原甲藻赤潮形成原因的依据。     

东海细菌丰度和生产力的季节变化及与浮游植物生物量和生产力的关系

The East China Sea is a productive marginal sea with a wide continental shelf and plays an important role in absorbing atmospheric carbon dioxide and transferring terrigenous organic matter to the open ocean. To investigate the roles of heterotrophic bacteria in the biogeochemical dynamics in the East China Sea, bacterial biomasses(BB) and productions(BP) were measured in four cruises. The spatial distributions of the BB and the BP were highly season-dependent. Affected by the Changjiang River discharge, the BB and the BP were high in shelf waters(bottom depth not deeper than 50 m) and generally decreased offshore in August 2009. In December 2009 to January 2010, and November to December 2010, the BB and the BP were high in waters with medium bottom depth. The onshore-offshore decreasing trends of the BB and the BP also existed in May–June 2011, when the BB was significantly higher than in other cruises in shelf break waters(bottom depth deeper than 50 m but not deeper than 200 m). The results of generalized additive models(GAM) suggest that the BB increased with the temperature at a range of 8-20°C, increased with the chlorophyll concentration at a range of 0.02–3.00 mg/m3 and then declining, and decreased with the salinity from 28 to 35. The relationship between the temperature and the log-transformed bacterial specific growth rate(SGR) was linear. The estimated temperature coefficient(Q10) of the SGR was similar with that of the phytoplankton growth. The SGR also increased with the chlorophyll concentration. The ratio of the bacterial to phytoplankton production ranged from less than 0.01 to 0.40, being significantly higher in November–December 2010 than in May–June 2011. Calculated from the bacterial production and growth efficiency, the bacterial respiration consumed, on average, 59%, 72% and 23% of the primary production in August 2009, November–December 2010, and May–June 2011, respectively.     

温度、盐度对具齿原甲藻生长的影响及其与中肋骨条藻的比较

在无菌条件下,单种培养具齿原甲藻以研究温度和盐度对其生长的影响。实验设计了5个温度梯度和6个盐度梯度,并计算了不同培养条件下藻细胞在指数生长期的比生长率。实验结果表明：具齿原甲藻生长的最适温、盐范围分别为22℃和25～31。温度对藻类生长的影响比盐度的要明显得多,而且藻生长的最适盐度有随着温度升高向低盐度偏移的趋势。同时,实验研究了同样条件下中肋骨条藻的生长情况,并与具齿原甲藻进行了比较,以试图探讨东海大规模爆发具齿原甲藻赤潮的原因。     

2011年春夏季黄海和东海微型浮游动物类群组成及其摄食的研究

为了解春夏季黄海和东海微型浮游动物类群及其摄食生态,于2011年春季和夏季在黄海、东海,通过稀释法测定浮游植物生长率及微型浮游动物对浮游植物的摄食率,同时应用显微分析技术研究了微型浮游动物丰度及其类群组成．结果表明：（1）春季,黄海、东海微型浮游动物丰度为1800～21833个／dm3,夏季的为67～6175个／dm3;春季,其微型浮游动物生物量为8．71-60．58ug/dm3,夏季的则为0．44～30．25ug／dm3（其生物量以c含量计）．（2）春季、夏季黄海和东海浮游植物的生长率及其标准偏差分别为0．78±0．35、1．62±0．83d-1,而春季的显著低于夏季（P〈0．05）．春季、夏季其微型浮游动物的摄食率及其标准偏差分别为0．98±0．32、0．92±0．57d-1,无显著性差异（p〉0．05）．春季,微型浮游动物摄食浮游植物现有生物量的61％±13％,占初级生产量的131％±58％;夏季,微型浮游动物摄食浮游植物现有生物量的54％±22％,占初级生产量的70％±44％．春、夏季,黄海和东海微型浮游动物对浮游植物初级生产量的摄食比例较高．     

利用围隔实验研究赤潮过程中藻细胞荧光能力

2002年5月和2003年5月在东海赤潮现场进行了添加营养盐诱发赤潮的船基围隔实验。通过测定赤潮藻活体荧光和DCMU增强荧光研究赤潮生消过程中藻细胞荧光能力的变化,揭示在赤潮形成阶段的藻细胞增长期细胞荧光能力较强,反之,在赤潮消亡过程中随着生物量和叶绿素a下降,细胞荧光能力也随之下降。不同围隔中生物量和叶绿素a有较大差别,而细胞荧光能力差别不大。这说明细胞荧光能力的大小与生物量无关,而是取决于藻细胞的生理状况。各围隔中加入DCMU后的增强荧光与正常荧光之间的差值(Fd-F)在赤潮发展过程中均增大,在赤潮消亡过程中均减小。根据它的大小和细胞荧光能力可初步判定赤潮是处于发展过程还是消亡过程。     

南海北部及台湾海峡夏季自养与异养区域的分布

采用黑白瓶方法,在2012年夏季测定了台湾海峡及南海北部16个站位群落总的初级生产力(gross primary production,GPP)和群落呼吸(community respiration,CR),总的初级生产力GPP水柱积分平均值为106.6±7.51mmol O2 m–2·d–1(mean±SE,以下同),群落呼吸CR平均为131.1±5.95mmol O2 m–2·d–1,净群落生产力(net community production,NPP)变化范围为-179.0~377.6mmol O2 m–2·d–1(中值为-40.4mmol O2 m–2·d–1)。受上升流的影响,琼东海域呈现明显的自养状态。在珠江口,由于珠江冲淡水的流入,该区域也呈现自养状态。相反,台湾海峡近岸以及粤东近岸均为异养区域。由此可见,异养区域的群落呼吸并不是完全由本地初级生产力决定,有机碳在空间上的输送对海洋浮游生物群落新陈代谢的影响可能极为重要。