【作者】 周凯；

【导师】 黄长江；

【作者基本信息】 暨南大学 ， 水生生物学， 2002， 博士

【摘要】 柘林湾位于粤、闽交界处，海域面积68～70km²，是广东省粤东地区12个重要海湾之一。由于良好的避风条件，从上世纪八十年代末以来，柘林湾海水养殖业发展迅速，养殖规模不断扩大，养殖网箱已达4万多箱，贝类养殖面积近20km²。距柘林湾约10公里处的深澳湾是南澳岛唯一的网箱养殖区，其水域面积为13.3km²。其中，养殖网箱0.3万格，牡蛎养殖面积6.1km²。由于养殖规模扩大化所带来的二次污染使两湾海域的生态环境发生了巨大变化，并成为赤潮多发区和生态脆弱区。为此，作者于2000年5月～2001年5月对柘林湾海域及邻近的深澳湾海域进行了一般理化因子、营养盐、浮游植物群落结构和叶绿素a的周年调查。本文除了反映以上调查的结果，还将探讨浮游植物与营养盐之间的关系及其对周边环境胁迫的响应。 调查期间，在柘林湾共设8个采样点，深澳湾共设3个采样点。采样频率为冬季每月2次，其余季节每月3～4次，每次现场调查均于高潮前后1.5小时内完成。浮游植物样品采集后立即用鲁哥氏液固定，带回实验室在显微镜下进行认种和计数。水化样品采集后立即经0.45μm的Millipore滤膜过滤并低温保存，在2～3小时内带回实验室后，立即用荷兰SKALAR水质微量流动注射分析仪测定硝态氮（NO₃-N）、亚硝态氮（NO₂-N）、氨氮（NH₄-N）和活性磷（PO₄-P）。用日本岛津UV-2501紫外／可见分光光度计进行活性硅（SiO₃-Si）、溶解铁和叶绿素a的测定。 柘林湾海域各营养盐含量基本表现为湾内高于湾外，近岸高于离岸的格局，符合人口密集的半封闭近岸内湾的特征。无机氮和硅与盐度之间呈显著负相关关系，相关系数分别为-0.511（p＜0.0001）和-0.600（p＜0.0001），这表明由黄冈河和柘林湾周边排污排废系统入海的工、农业废水和缄镇居民生活污水携带的营养盐是柘林湾海域营养盐的最主要来源。深澳湾海域虽然没有河流径流的影响，但其大量营养盐平面分布仍表现为湾内向湾外递减的趋势。无机氮和硅与盐度之间的负相关关系（相关系数分别为-0.266，p＜0.01和-0.444，p＜0.001）表明该湾大量营养盐主要是来源于湾内增养殖业及周边居民生活污水的排放。两湾活性磷与盐度之间的非保守性关系可能与海区悬浮颗粒对磷的吸附作用以及网箱养殖区内的高磷含量有关。柘林湾海域溶解铁主要来源于黄冈河径流和浮游植物胞内铁的生物循环，深澳湾海域溶解铁主要是受生物活动及湾外海水的影响。因此，两湾溶解铁与盐度之间呈非保守性关系。 调查期间，柘林湾湾内无机氮、磷、硅和铁的周年平均值分别为25.2、2.14、65.1μmol／1和71.1μg/1。与国外海湾相比，其无机氮含量明显偏低，但在国内居于中流水平。相比之下，无机磷、硅酸盐的含量则比国内外大多数海湾高得多。其中，氮、磷含量分别为国家三类海水 Ox01水质标准的 1＊ 8倍和 1．48倍。深澳湾海域的无机氮、磷、硅和铁的周年平均值分别为 15二、l·63、39．6 PmoUI和 66．2 Pg／l，其中氮、磷含量分别超过国家二类和三类海水的水质标准。这一切都充分反映出两湾海域富含磷、硅、铁，也不缺氮的特征，由此构成的富营养化特征和生态负面效应有其独特的一面。 以 JustiC（1995）和 DOrtch等（1992）提出的营养盐化学计量限制标准来衡量，拓林湾海域浮游植物生长受控于单一营养盐限制因子的出现率为氮41．8％，磷22．9％，硅2．36％。深澳湾海域浮游植物生长受控于单一营养盐限制因子的出现率为氮42．9％、磷ZI．0％、硅4．76％。由此表明，两湾海域的硅十分丰富，磷也不缺乏，它们不成为限制因子，氮则是海区游植物生长的主要限制因子，这对于生长繁殖需要硅的硅藻来说具有较大的竟争优势。因此，海域硅藻赤潮发生的机会就会明显增多，而发生甲藻赤潮的可能性较小。 调查期间，拓林湾海域共有浮游植物 54属 153种。其中硅藻为优势类群，共 37属 114种，占总种数的74．sl％；甲藻15属36种；其它2属3种。深澳湾海域共采集到浮游植物50属108种。其中，硅藻33属73种，占总种数67．6％；甲藻15属33种，其它2属2种。硅藻在调查期间一直处于优势地位，其细胞数量年均值分别占浮游植物总细胞数的 99．l％（拓林湾）和98．8％（深澳湾），而甲藻只占0厂8％（拓林湾）和1．co／（深澳湾）。两湾海域优势种的种类组成及周年变化较为相同，除中肋骨条藻（Skeletonema costatUm）为常年优势种外，春季优势种较多，主要有丹麦细柱藻（二印tOCyindna daniC。）、尖刺拟菱形藻（Pseluro’litssc，lia尸p us）、菱形海线藻（乃alas九m——。n允2刀劝加饲e压）、旋链角毛藻（C力。totw c——砧6t1M）和窄隙角毛藻（Chaet奶his）；夏季优势种主耍有浮动弯角藻（EIJca7，：DIa ZDodac。）、窄隙角毛藻；秋季优势种主要有尖刺拟菱形藻、菱形海线藻和具槽直链藻（Melosira suleata）；冬季的优势种只有具槽直链藻。 虽然拓林湾和深澳湾海域营养盐的平面分布呈湾内高于湾外，但两湾的浮游植物种类和细胞数却表现出湾外高于湾内的分布格局。调查期?更多还原

【Abstract】 Zhelin Bay with water area of 68~70 km2 is one of the most important estuaries for mariculture in the east of Guangdong, China. There were more than 40,000 net-cases of fishery culture and approximately 20 km2 of shellfish area in Zhelin Bay. In addition, there were about 3,000 net-cases of fishery culture and approximately 6.1 km2 of oyster culture in Shen’ao Bay located on Nan’ao Island, where is about 10 km away from Zhelin Bay. With constantly increasing in fishery culture and nutrient input to the estuaries within decades, the ecological environment has been significantly changed, resulting in red tide hitting this area frequently and the ecosystem being seriously affected. For this reason, we investigated the temporal and spatial distribution of temperature, salinity, dissolve oxygen, nutrients, phytoplankton, biomass, chlorophyll a in Zhelin Bay and Shen’ao Bay from May 2000 to May 2001. The thesis presents the investigated results and the relationship between phytoplankton and nutrients.Water samples were collected from eight stations in Zhelin Bay and three stations in Shen’ao Bay weekly (March~November) or biweekly (December-February). Sampling was scheduled to cover the period around high tide (?.5hr). Samples for phytoplankton were fixed with acid lugol solution in situ and analyzed with the microscope in laboratory. Samples for nutrients were filtered with 0.45um Millipore filter in situ, then transported in ice to the laboratory within 2hr. The NO3-N, NO2-N, NH4-N and PO4-P were analyzed by the SKALAR Channel Seawater Segmented Flow Nutrient Analyzer. The SiOs-Si, Fe and Chlorophyll a were analyzed by the SHMADZU UV-2501 PC.In both bays, the contents of dissolved inorganic nitrogen, phosphate and silicate decreased gradually from inner bay to outer bay, descent from nearshore to offshore. The significant inverse correlations were found between dissolved nitrogen and salinity (r=-0.511,p<0.0001) and between silicate and salinity (r=-0.600, p<0.0001) in Zhelin Bay. This indicates that nutrient loads in Zhelin Bay were mainly originated from Huanggang river and discharge of industrial, domestic and mariculture waster around the bay. The inverse correlation between dissolved nitrogen andsalinity(r=-0.266,p<0.01) and between silicate and salinity (r=-0.444, p<0.01) in Shen’ao Bay indicated that discharge of mari culture and domestic waster were the mainly nutrient source of the bay. Because a phosphate "buffer" from exchange between particulate and dissolved phases influenced phosphate concentrations, the phosphate-salinity relationship indicated the non-conservative in both bays. The iron-salinity relationship also indicated the non-conservative, displaying both strong biological removal and input signals.The annual average of dissolved nitrogen, phosphate, silicate and iron concentration were 25.2 umol/1, 2.14 umol/1, 65.2 umol/1 and 71.1 ug/1, respectively, in Zhelin Bay. Compared with most estuaries in world, the nitrogen concentration was not so much in Zhelin Bay, whereas the phosphate, silicate and iron concentration were much higher. The contents of nitrogen and phosphate were 1.18 and 1.84 times the third-class seawater standard in China, respectively. The annual average of dissolved nitrogen, phosphate, silicate and iron concentration were 15.2 umol/1, 1.63 umol/1, 39.6 umol/1 and 66.2 ug/1, respectively, in Shen’ao Bay. The contents of nitrogen and phosphate were higher than the second-class and the third-class seawater standard in China, respectively. All of those indicated that eutrophication caused by overload of mariculture have made great pressure on both bays.According to the stoichiometric limitation standard of Justic (1995) and Dortch et ai, (1992), the plots of atomic DIN: P, Si: P and Si: DIN ratios in the water column of Zhelin Bay displayed the stoichiometric limitation of 41.8% in DIN, 22.9% in P and 2.36% in Si. In Shen’ao Bay, the stoichiometric limitations were 42.9% in DIN, 21.0% in P and 4.76% in Si. This result showed that N limitation might be more prevalent更多还原