Phytoplankton community characteristics in the coastal waters of the southeastern Arabian Sea Phytoplankton community characteristics in the coastal waters of the southeastern Arabian Sea

Remote sensing applications are important in the fisheries sector and efforts were on to improve the predic-tions of potential fishing zones using ocean color. The present study was aimed to investigat...     

Stomatocysts of Chrysophytes in Lake Shira

正The chrysophytes are distributed over all the continents.As a rule,these are planktonic,freshwater,cold-water inhabitants.There are as well saltish-water chrysophytes species of genera Chrysococcus,Dinobryon,     

ENCLOSURE EXPERIMENTS ON AND LACUSTRINE PRACTICE FOR ELIMINATING MICROCYSTIS BLOOM

Microcystis bloom, one of the most objectionable characteristics of eutrophication in tropical and subtropical waters, occurred in Donghu Lake (East lake) of Wuhan every summer from the 1970s up to 1984, but from 1985 up to now failed to occur there. The cause of its disappearance rema-ined in obscurity until recently. In situ enclosure experiments in the lake for three years showed that the stocking of the filter-feeding silver carp ( Hypophthalmichthys molitrix ) and big-head carp (Aristichthys nobilis ) played a decisive role in eliminating Microcystis bloom from the lake; but that recurrence of the bloom is possible under certain conditions. This paper presents the details and the results of enclosure ex-periments. The authors‘ analysis of fish biomass data obtained by echo-sounding and the fishery produc-tion of the lake over the years, revealed that the recurrence of Microcystis bloom can be prevented so long as the combined biomnss of silver carp and big-head carp remains at or exceeds 50 g per cubic meter of lakewater, as was the case in the lake‘s 1985 fish yield of 1015 t.     

珠海地区凡纳滨对虾淡水养殖池浮游植物群落的演替

对珠海凡纳滨对虾淡水养殖池塘浮游植物及其理化因子进行了调查和分析,结果表明:调查中共检出浮游植物143种,优势种主要有林氏藻、螺旋鱼腥藻、小颤藻、微囊藻和点状平裂藻等,物种多样性指数在0.24~2.77之间,优势度与多样性指数呈显著的负相关,相关系数r=-0.984;而均匀度与多样性指数呈显著的正相关,相关系数r=0.967,养殖后期优势度不高,浮游植物的密度及化学因子的浓度到后期都有所上升,藻类密度的剧烈变化会引起氨氮和硫化氢含量的变化;藻类密度的波动滞后于无机氮的波动,群落演替具有突发性、时间短、速度快等特点。     

EXAMINATION OF SILICATE LIMITATION OF PRIMARY PRODUCTION IN JIAOZHOU BAY, CHINA Ⅰ. SILICATE BEING A LIMITING FACTOR OF PHYTOPLANKTON PRIMARY PRODUCTION

Jiaozhou Bay data collected from May 1991 to February 1994, in 12 seasonal investigations, and provided the authors by the Ecological Station of Jiaozhou B ay, were analyzed to determine the spatiotemporal variations in temperature, light, nutrients (NO-3-N, NO-2-N, NH+4-N, SiO2-3-Si, PO3-4-P), phytoplankton, and primary production in Jiaozhou Bay. The results indicated that only silicate correlated well in time and space with, and had important effects on, the characteristics, dynamic cycles and trends of, primary production in Jiaozhou Bay. The authors developed a corresponding dynamic model of primary production and silicate and water temperature. Eq.(1) of the model shows that the primary production variation is controlled by the nutrient Si and affected by water temp erature; that the main factor controlling the primary production is Si; that water temper ature affects the composition of the structure of phytoplankton assemblage; that the different populations of the phytoplankton assemblage occupy different ecologica l niches for C, the apparent ratio of conversion of silicate in seawater into phytoplankton biomas and D, the coefficient of water temperature's effect on phytoplankton biomass. The authors researched the silicon source of Jiaozhou Bay , the biogeochemical sediment process of the silicon, the phytoplankton predominan t species and the phytoplankton structure. The authors considered silicate a limit ing factor of primary production in Jiaozhou Bay, whose decreasing concentration of silicate from terrestrial source is supposedly due to dilution by current and up take by phytoplankton; quantified the silicate assimilated by phytoplankton, the intrins ic ratio of conversion of silicon into phytoplankton biomass, the proportion of silicate uptaken by phytoplankton and diluted by current; and found that the primary production of the phytoplankton is determined by the quantity of the silicate assimilated by them. The phenomenon of apparently high plant-nutrient concentrations but low phytoplankton biomass in some waters is reasonably explained in this paper.     

2011年夏季南大洋普里兹湾颗粒态生物硅的分布与变化特征

利用中国第27次南极科学考察期间获得的颗粒物样品,对南大洋普里兹湾海域水体中颗粒态生物硅的含量及分布特征进行了初步研究,分析了该海域颗粒态生物硅与营养盐、浮游植物以及颗粒有机碳之间的关系,同时结合历史数据对比了颗粒态生物硅的年际变化情况。研究结果显示：在2011年夏季普里兹湾表层水体中颗粒态生物硅含量在0.76-19.72μmol/ dm3之间变化,平均为6.06±4.55μmol/ dm3。在表层水体中的分布趋势是67°S以南的湾内区域颗粒态生物硅含量明显高于67°S以北的湾外区域,最大值出现在普里兹湾陆架区。在垂向分布上,P3断面水体中颗粒态生物硅含量随深度增加而减少。根据不同年份即24,25,26,27次南极科学考察期间获取的数据对比分析显示,颗粒态生物硅含量虽存在一定的年际差异,但是在普里兹湾的分布趋势基本一致。颗粒态生物硅含量的变化特征与硅酸盐相反与叶绿素a、颗粒有机碳相似。     

基于MODIS数据的太湖浮游植物物候变化及其对水表温度的响应

浮游植物物候能够反映浮游植物的生长变化与湖泊生态系统的变化,水温、营养盐浓度等因素对物候有重要影响。太湖富营养化程度较高,水温的影响作用日趋显著,物候与水温关系的研究对理解、控制和改善太湖生态系统具有重要意义。本研究利用2003—2018年MODIS遥感数据计算浮游植物物候指标和湖泊水表温度（Temperature of Water Surface,LSWT）,通过分析太湖浮游植物物候时空变化特点探究了不同区域的物候特征,并结合LSWT揭示了浮游植物物候对LSWT变化的响应关系。结果表明：① 不同浮游植物物候指标具有不同空间分布特点,水华发生次数、峰值叶绿素a（Chla）浓度和水华总持续时间呈现由西部沿岸向湖心区递减的趋势;浮游植物生长开始时间和峰值Chla发生时间分布复杂但在沿岸区域相对较早;② 太湖可被划分为4种具有不同物候特征的区域,Ⅰ类区域主要位于贡湖湾、东部沿岸以及太湖中部开阔水域,该区Chla浓度范围为50~60 μg/L,且波动平缓,水华发生次数最少、开始最晚、持续时间最短;Ⅱ类区域主要分布于太湖西部沿岸,Chla浓度范围为50~90 μg/L且变化剧烈,该区水华发生次数最多、开始最早、持续时间最长;Ⅲ和Ⅳ类属于过渡区域,前者主要分布于梅梁湾、竺山湾及入湾口,后者主要位于南部沿岸以及太湖中部;③ 浮游植物物候对LSWT变化的响应受营养水平影响,当营养水平较高时,浮游植物的生长受LSWT的促进作用显著,LSWT年际变化的升高趋势对浮游植生长物候提前、生物量增加的影响明显,反之,则LSWT变化对浮游植物生长的影响减弱。