养马岛扇贝养殖区浮游藻类的生态特征及其与环境因子的关系

Ecological characteristics of planktonic algae and their relationship with environmental factors in scallop culture area of Yangma Island

2018年5—11月对养马岛扇贝养殖区的3个海域进行了7个航次的调查,分析了浮游藻类群落结构的组成、密度、Shannon-Winner多样性指数、Pielou均匀度指数、Margalef丰富度指数和Mc-Naughton优势度指数,并应用典范对应分析(CCA)探讨了环境因子对养殖区浮游藻类优势种的影响。结果表明:养马岛扇贝养殖区检测出的浮游藻类共有5门34属60种,以硅藻门和甲藻门为主,分别占73.33%和13.33%;浮游藻类的密度范围为(1.49~124.92)×10^4 个/L,最高密度和最低密度分别出现在6月和11月;优势种包括尖刺伪菱形藻( Pseudonitzschia pungens )、等鞭金藻( Isochrysis sp.)、蓝隐藻( Chroomonas sp.)、柔弱几内亚藻( Guinardia delicatula )、扁面角毛藻( Chaetoceros compressus )和丹麦细柱藻( Leptocylindrus danicus )等;浮游植物多样性指数、均匀度指数以及丰富度指数的变化范围分别为0.51~3.62、0.14~1.00、1.08~4.12;CCA分析表明无机氮、无机磷、盐度和温度为影响该海域浮游藻类群落分布的主要因子。总体而言,养马岛扇贝养殖区的浮游藻类分布合理,结构稳定,适合扇贝养殖。

The scallop culture area of Yangma Island is located in Yantai Shiliwan Bay.The latter is an ear-shaped semi-closed bay.There are many rivers such as Xin an River along the coast.It is an important shallow sea culture area in the North Yellow Sea.As an important primary producer in the marine ecosystem,phytoplankton has the characteristics of short life cycle and sensitivity to environmental changes,and is used as an important indicator for the nutrient grade evaluating of water bodies.Its community structure can better reflect nutritional status of aquatic ecosystems.Planktonic algae has the ability to absorb nitrogen and phosphorus,which can purify water bodies and help scallops grow.However,when a large amount of land-source input causes the concentration of nitrogen and phosphorus to be too high,the overgrowth of phytoplankton will occur,which may cause red tide.Wang Wenjun analyzed the outbreak of marine card shield algae in the Sishili Bay in 2014,which proved that excessive nitrogen nutrient salt was a key factor in the occurrence of this red tide.In addition,phytoplankton is also an important bait for scallops.Zhang Lihong studied the feeding habits of scallops in Sanggou Bay and found that the algae that scallops mainly feed on are diatoms and dinoflagellates.Wang et al surveyed Yantai Shiliwan Bay and showed that the dominant species of planktonic algae were mainly diatom-diatomaceous-branched algae in summer,and the main season was mainly diatom,which was consistent with the feeding habit of cultured scallops.Therefore,the detection of the composition and density of phytoplankton in the cultured sea area is of great significance for the monitoring of the ecological environment of the sea area and the rational culture and breeding of scallops.In this paper,the investigation of seven voyages were carried out in three scallop culture areas of Yangma Island from May to November in 2018.The composition,density,Shannon-Winner diversity index,Pielou evenness index,Margalef richness index and Mc-Naughton dominance index of phytoplankton community structure were analyzed,and the influence of environmental factors on phytoplankton dominant species in Yangma Island scallop culture area was discussed by canonical correspondence analysis (CCA).The results showed that there were 60 species of planktonic algae in 34 genera of 5 phyla detected in this area,mainly diatom and dinoflagellate,accounting for 73.33% and 13.33% respectively.The density of phytoplankton ranges from 1.49× 10^4 to 124.92× 10^4 cells/L,with the highest density occurring in June and the lowest density occurring in November.Dominant species include Pseudonitzschia pungens , Isochrysis sp ., Cryptococcus sp., Guinardia delicatula , Chaetoceros compressus and Leptocylindraceae danicus etc.The diversity index,evenness index and richness index of phytoplankton varied from 0.51 to 3.62,0.14 to 1.00 and 1.08 to 4.12,respectively.CCA analysis showed that inorganic nitrogen,inorganic phosphorus,salinity,pH and temperature were the main factors affecting phytoplankton in the sea area,and the response mechanisms of various phytoplankton to environmental factors were different.In general,the phytoplankton in scallop culture area of Yangma Island was distributed reasonably and had stable structure,which was suitable for scallop culture.