| 摘要: |
| 流沙湾是中国海水珍珠“南珠”的主产区和广东省重要的贝类养殖区。为评估湾内养殖活动的环境效应，于2015~2016年对流沙湾海区进行了夏(8月)、秋(11月)、冬(2月)、春(5月) 4个季节的浮游植物和海水理化因子调查。共检出浮游植物171种，包括硅藻门43属122种、甲藻门 10属44种、蓝藻门2属2种、金藻门2属2种和裸藻门1属1种。流沙湾内湾浮游植物细胞丰度为(0.05~79.04)×104个/L，夏季>春季>秋季>冬季，且夏季丰度远大于其他三季，内湾和外湾差异不显著。春季须状角毛藻(Chaetoceros crinitus)、红海束毛藻(Trichodesmium erythraeum)和明壁圆筛藻(Coscinodiscus debilis)为主要优势种，夏季优势种主要为中肋骨条藻(Skeletonema costatum)，秋季优势种主要为拟弯角毛藻(Chaetoceros pseudocurvisetus)、奇异棍形藻(Bacillaria paradoxa)、洛氏角毛藻(Chaetoceros lorenzianus)，冬季主要优势种为威氏圆筛藻(Coscinodisus wailesii)、柔弱根管藻(Rhizosolenia delicatula)、岛脆杆藻(Fragilaria islandica)。其中，奇异棍形藻为春、秋、冬季的优势种，红海束毛藻为春、夏、秋季的优势种。冗余分析表明，流沙湾浮游植物优势种在春季与水温和氨氮密切相关，夏季受透明度显著影响，而在秋、冬季受亚硝酸氮含量影响显著。流沙湾不同养殖区的浮游植物多态性和丰度有明显季节差异。与2012年相比，流沙湾外湾的养殖覆盖率提高了近50%，内湾的珍珠贝养殖减少了近90%，养殖品种、规模和分布格局都发生了明显变化，目前流沙湾的浮游植物群落特征正是对其变化的一种响应。夏季鱼类网箱养殖提高了水域营养盐水平并降低了浮游植物多样性。大规模的扇贝养殖则导致了扇贝养殖区浮游植物丰度的降低。 |
| 关键词: 流沙湾 浮游植物 聚类分析 养殖活动 |
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| Phytoplankton Community Characteristics in Different Seasons and Their Relationship with Aquaculture in Liusha Bay |
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SU Jiaqi1,2, ZHU Changbo1,2, LI Junwei1,2, LI Ting1,2, CHEN Suwen1,2, XIE Xiaoyong1,2, ZHANG Bo1,2
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1.Key Laboratory of South China Sea Fishery Resources Exploitation & Utilization, Ministry of Agriculture and Rural Affairs;2.South China Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Guangdong Provincial Key Laboratory of Fishery Ecology and Environment, Guangzhou 510300
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| Abstract: |
| Liusha Bay is one of the main aquaculture areas of marine mollusks in Guangdong Province, characterized by the main producing areas of South Pearl. To assess the environmental effects of aquaculture activities, the phytoplankton composition, abundance, community structure, diversity, and water physicochemical factors were investigated in each season from August 2015 to May 2016. In total, 171 phytoplankton species were detected, with 122 species of diatom belonging to 43 genera, followed by dinoflagellates represented by 44 taxa (10 genera), blue-green algae by two taxa (two genera), chrysophyceae by two taxa (two genera), and euglena by one taxa (one genus). The range of phytoplankton density was 0.05×104~79.04×104 cells/L, which ranked as: summer > spring > autumn > winter. In general, the phytoplankton density in the outer bay was similar to that in the inner bay. The abundance of phytoplankton in summer was distinctly higher than that in the other three seasons. The most common dominant species were Chaetoceros crinitus, Trichodesmium erythraeum, and Coscinodiscus debilis in spring, Skeletonema costatum in summer, Chaetoceros pseudocurvisetus, Bacillaria paradoxa, and Chaetoceros lorenzianus in autumn, and Coscinodisus wailesii, Rhizosolenia delicatula, and Fragilaria islandica in winter. B. paradoxa was the dominant species in spring, autumn, and winter. T. erythraeum was the dominant species in all seasons except for autumn. Redundancy analysis suggested that the main variables affecting the dominant species were water temperature and nitrate (NO3-N) in spring, transparency in summer, and nitrite (NO2-N) in autumn and winter. The phytoplankton diversity and abundance of different cultured zones presented seasonal differences. Compared to 2012, the total coverage of the aquaculture zone in 2015 increased by approximately 50% in the outer bay. Furthermore, coverage of the pearl oyster farming zone decreased by about 90% in the inner bay. Both the distribution of the aquaculture zone and the scale of the mariculture species were significantly changed, and the characteristics of the phytoplankton community responded to these changes. In summer, cage fish farming could efficiently increase nutrient content in seawater and decrease phytoplankton diversity. Furthermore, phytoplankton abundance was decreased by large-scale scallop culture. |
| Key words: Liusha Bay Phytoplankton Cluster analysis Aquaculture activity |
