南海北部浮游植物生长对营养盐的响应

2004年夏季作者在南海北部海域研究了浮游植物生长的营养动力学,结合物理-化学过程对浮游植物生物量分布的影响与机制进行了研究,阐明了水平对流和中尺度涡对营养盐分布的影响及浮游植物生长和现存生物量对其的响应。受西南季风和东向沿岸流作用所形成的Ekman输送的影响,南海北部海岸带表层海水作离岸运动,使深层富含营养盐的冷水爬坡涌升到表层来补充,激发浮游植物生物量迅速增长。海区反气旋涡使海水辐聚下沉,造成水体具高温、低盐、高溶解氧浓度、低营养盐浓度和低浮游植物生物量。同时通过现场营养盐加富试验,发现该海域营养盐是浮游植物生长的主要限制因子,而且是多种营养元素共同限制了浮游植物的生长,添加单一的营养盐并不能促进浮游植物的生长。在生物量出现增长的试验组中,营养盐添加不仅促使浮游植物生物量的增长,而且也改变了浮游植物的粒级结构和群落结构。例如,在站S1008,培养前叶绿素a浓度为0.28 mg.m-3,加富培养60 h后浮游植物生物量在NP和NPSi的试验组中有显著的增加,叶绿素a浓度分别达1.07 mg.m-3和1.19 mg.m-3;培养前粒度分级叶绿素a主要以Pico级份占优势,而加富试验结束后,在NP和NPSi的试验组以Nano级份占优势,其它试验组仍以Pico级份占优势;同时,在培养后生物量出现增长的试验组,浮游植物群落的优势类群从甲藻向硅藻演替。     

夏季西南印度洋叶绿素a分布特征

分析了2011年1月西南印度洋叶绿素a的分布特征及其粒级结构,并结合水动力学环境和营养盐数据探讨了其主要影响因素。结果表明,西南印度洋副热带涡流(IOSG)区表层叶绿素a浓度较低,不超过0.07 mg/m3,次表层叶绿素a浓度最大值所在水层较深,超过100 m;副热带聚集区(SCZ)表层叶绿素a浓度较高(0.164—0.247 mg/m3),次表层叶绿素a浓度最大值出现在50—70 m层。硝酸盐是该海区浮游植物生长的主要限制因素。微微型(pico)粒级的浮游植物占绝对优势,所有站位其对总叶绿素a的平均贡献率为71.1%,微型(nano)粒级次之(24.2%),小型(net)粒级所占比例最小(4.7%),其中IOSG区pico粒级对总叶绿素a的平均贡献率为77.9%,SCZ的pico粒级对总叶绿素a的平均贡献率为66.7%。IOSG区和SCZ海区之间水动力学环境的不同,可能导致了这两个海区叶绿素a的分布特征及粒级结构的较大差异。     

印度洋南赤道流区水体叶绿素a的分布及粒级结构

根据2010年4—5月印度洋南赤道流区的综合环境调查资料,对印度洋南赤道流区叶绿素a浓度分布和浮游植物的粒级结构等进行了分析. 结果表明,调查海区水体层化明显,表层水温较高,营养盐浓度较低。调查海区东部测站的数据显示该区域可能受到来自印度尼西亚贯穿流和南爪哇流的影响,有高温低盐的特点。叶绿素a浓度在该海区的分布具有以下特点：（1）表层叶绿素a浓度在整个调查海区虽然普遍较低（平均为（0.1220.052） mg/m3）,但具有明显的空间区域化特征：印度洋南赤道流区中部,叶绿素a浓度较低,站位间分布均匀;东部叶绿素a浓度相对较高,不同测站叶绿素a浓度差异明显.（2）整个调查区域叶绿素a浓度垂直分布具有明显的单峰结构,其最大值分布在60—80m水层,位于营养盐跃层内.（3）叶绿素a的粒级结构分析结果显示,pico级份的浮游植物对叶绿素a的贡献占主导地位,平均为75%,nano级份的贡献平均为20%,net级份对叶绿素a的贡献最小,平均仅有5%. 对比本次调查和在其它海区的研究,表明印度洋南赤道流区属于典型的低纬度寡营养海区,低的营养盐浓度（特别是NO3-浓度）是该海区浮游植物生长的主要限制因素之一.     

獐子岛及邻近海域秋季浮游植物的粒级结构及其影响因素

于2015年10月对獐子岛及邻近海域进行了航次调查,研究了獐子岛及邻近海域浮游植物粒级结构的空间分布特征及其环境影响因素。结果表明,秋季表层总叶绿素a、小型(20μm)、微型(2—20μm)和微微型(0.45—2μm)浮游植物叶绿素a浓度的范围分别为0.52—1.25、0.03—0.81、0.33—0.91、0—0.09μg/L,平均叶绿素a的浓度分别为0.76、0.19、0.53、0.03μg/L,对叶绿素a总量的贡献率分别为23.77%、72.26%和3.98%;底层总叶绿素a、小型(20μm)和微型(2—20μm)浮游植物叶绿素a浓度的范围分别为0.14—1.5、0.04—1.04、0.08—0.47μg/L,平均叶绿素a的浓度分别为0.46、0.22、0.24μg/L,对叶绿素a总量的贡献率分别为41.46%、58.50%。从垂直分布上来看,总叶绿素a浓度垂直变化为,表层底层;小型浮游植物垂直分布较为均匀;微型浮游植物垂直变化为,表层底层;微微型浮游植物垂直变化为,表层底层,且在表、底层均保持较低水平。秋季表层微型浮游植物(2—20μm)浓度与盐度呈正相关。底层总叶绿素a浓度与磷酸盐浓度呈正相关,小型浮游植物(20μm)浓度与磷酸盐和硅酸盐浓度均表现为正相关,微型浮游植物(2—20μm)浓度与温度呈正相关。统计分析结果表明,温度、盐度、磷酸盐及硅酸盐浓度是影响獐子岛及邻近海域秋季浮游植物粒级结构变动的重要因素。     

胶州湾叶绿素a浓度及浮游植物的粒级组成

2008年2、5、8和11月对胶州湾及邻近水域中表层叶绿素a浓度和浮游植物粒级组成进行了调查.结果表明:胶州湾内和湾外表层叶绿素a年平均浓度分别为4.90和2.03 mg·m^-3;叶绿素a浓度的平面分布呈现自东北部及近岸向中部、南部及湾外递减的趋势;叶绿素a浓度季节变化明显,冬季和夏季浓度较高,春季次之,呈现温带海域双峰型的变化趋势.胶州湾浮游植物粒级组成以微型浮游植物为主,平均占叶绿素a总量的60.9%,其次是小型浮游植物,超微型浮游植物所占比例最低,与我国近海浮游植物粒级组成基本一致.与历史资料相比,微型浮游植物所占比例有所增加,超微型浮游植物所占比例降低.     

北部湾北部海域夏季微型浮游动物对浮游植物的摄食压力

2011年8月份于北部湾北部海域5个观测站位获得的分层水样,分析了表层叶绿素a含量和表层微型浮游动物丰度以及类群组成;同时于现场采用稀释培养法研究了该海域浮游植物生长率(μ)和微型浮游动物的摄食率(g)。分析和测定结果表明:调查海区的微型浮游动物丰度400—1167个/L,类群组成以无壳纤毛虫为主;浮游植物的生长率为-1.50—1.13 d-1,微型浮游动物摄食率为0.33—1.08 d-1;推算微型浮游动物对浮游植物现存量以及初级生产力的摄食压力分别为28.1%—66.0%和-7.4%—438.4%。相对于中国其他海区,8月份北部湾北部海域微型浮游动物摄食速率处于中等水平。调查期间,广西沿海高生产力海区,浮游植物生长率大于微型浮游动物动物的摄食率,浮游植物生物量处于积累期;涠洲岛以南海域,浮游植物生产力较低,微型浮游动物摄食作用是控制浮游植物生长的重要因素。     

獐子岛海域冬季分级叶绿素a的分布特征及其影响因素

于2016年1月对獐子岛海域进行了航次调查,研究了獐子岛海域浮游植物粒级结构的空间分布特征及其环境影响因素。结果表明:冬季表层总叶绿素a、小型(20μm)、微型(2~20μm)和微微型(0.45~2μm)浮游植物叶绿素a浓度的范围分别为0.24~0.92、0.15~0.58、0.09~0.46、0~0.03μg·L-1,平均叶绿素a的浓度分别为0.69、0.36、0.33、0.002μg·L-1,小型、微型和微微型浮游植物对浮游植物总量的贡献率分别为51.72%、48.01%、0.26%;底层总叶绿素a、小型、微型和微微型浮游植物叶绿素a浓度的范围分别为0.29~1.77、0.12~1.45、0.17~0.50、0μg·L-1,平均叶绿素a的浓度分别为0.78、0.43、0.34、0μg·L-1,小型、微型和微微型浮游植物对浮游植物总量的贡献率分别为52.97%、47.03%、0;从垂直分布上来看,表、底层总叶绿素a及两种粒级浮游植物(20μm、2~20μm)的浓度均差异不显著,分布较为均匀;从水平分布上来看,总叶绿素a及两种粒级浮游植物(20μm、2~20μm)浓度的表、底层空间分布趋势相近,均呈现出由獐子岛海域西北部向南部逐渐降低的趋势。RDA分析表明,温度、盐度、溶解氧、颗粒态有机物、NO2--N和NH4+-N是影响獐子岛海域冬季浮游植物粒级结构变动的重要因素。     

长江口冬季和春季浮游植物的粒级生物量

根据2005年2月28日—3月10日和5月30日—6月4日在长江口及其邻近水域进行的多学科综合外业调查,报道了冬季和春季浮游植物粒级生物量的空间分布和组成特征,并探讨了影响浮游植物粒级生物量的环境因子.结果表明：冬季长江口及其邻近水域表层叶绿素a平均浓度为1.28 mg·m^-3,高值区集中在口门附近;小粒径浮游植物（<20 μm）对浮游植物生物量的贡献率为66.7%,但在冲淡水区大粒径浮游植物（>20 μm）占据优势.春季长江口及其邻近水域表层叶绿素a浓度大幅增加,口门内、外的平均值分别为0.67和6.03 mg·m^-3,122.5°—123.0° E间水域因水华爆发出现显著的叶绿素a高值区;小粒径浮游植物对浮游植物生物量的贡献高达83.5%,其优势在水华区尤为明显.典型站位浮游植物粒级生物量的垂向分布显示,2种粒径浮游植物叶绿素a浓度的差异随水深增加而减小,至底层二者浓度相当.根据所获的环境因子资料,盐度和营养盐是影响长江口及其邻近水域浮游植物粒级生物量分布和组成的重要环境因子.     

东海赤潮高发区春季叶绿素a和初级生产力的分布特征

2002年4-5月对东海海域进行了综合调查,分析了海区叶绿素a和初级生产力的分布特性．结果表明,大面站表层平均叶绿素a浓度为1．086mg·m-3．分级叶绿素a结果显示．春季东海浮游植物以微型和微微型(<20μm)占优势,其对海区叶绿素a的贡献为64％,超微型浮游植物(<5μm)占浮游植物生物量的27％．营养盐分布和浮游动物的摄食压力影响了叶绿素a及其粒级结构的分布．平均初级生产力为10．091mg·m-3·h-1。赤潮跟踪的R-03、RL-01、RG-01站的平均初级生产力为399．984mg·m-3·h-1．光和营养盐成为叶绿素和初级生产力平面分布的主要限制因子．表层叶绿素a和初级生产力均在调查海区的123·E纵断面冲淡区产生高值区．DC-11站浮游植物生物量异常高,表层叶绿素a达到9．082mg·m-3,初级生产力为128．79mg·m-3·h-1．但并未出现水色异常．     

2006年冬季南海北部浮游植物生物量和初级生产力及其环境调控

通过2006年2月在南海北部现场调查所获得的数据分析研究了海域的浮游植物现存量和生产力,结果表明冬季浮游植物的分布特征与东北季风引起的环流场的变化关系密切。调查海域水柱平均Chla浓度的变化范围为0.03～1.21mg&#183;m-3（平均（0.33&#177;0.33）mg&#183;m^-3）,高值区出现在广东沿岸及海南岛东部附近海域;初级生产力的分布范围为41.3～1040.0mgC&#183;m^-2d^-1。由于东北季风引起近岸水体混合剧烈,不利于浮游植物生长,因此虽然沿岸带Chla浓度（（0.53&#177;0.50）mg&#183;m^-3）较高,但初级生产力却是最低的,只有41.3mgC&#183;m^-2d^-1,同时冬季反气旋涡强度下降和底层富营养水的涌升,营养盐充足,因此开阔海的Chla浓度（（0.31&#177;0.30）mg&#183;m^-3）和初级生产力（（631.3&#177;578.0）mgC&#183;m^-&#183;2d^-1）均高。浮游植物粒度级份测定表明,Pico级份对冬季南海北部浮游植物现存量和生产力的贡献很大,特别是在开阔海区,分别占47%和66%。     

An HPLC analysis of the summer phytoplankton assemblage in Lake Baikal

1. The enormous size and spatial heterogeneity of Lake Baikal require rapid methods for large sample sets. We therefore tested the applicability of a novel, high‐performance liquid chromatography (HPLC)‐based, combination of methods for analysing phytoplankton. In July 2001, samples were collected in a transect across the lake at various depths down to 30 m. Phytoplankton (>3 μm) and autotrophic picoplankton (APP) were counted under light and epifluorescence microscopes, respectively. Pigments were analysed with HPLC. 2. The pigment data allowed the contributions of the dominant phytoplankton groups to the total chlorophyll a (Chl a) in the lake to be estimated by multiple linear regression and by the CHEMTAX matrix factorisation program. Three marker pigments, fucoxanthin, lutein and zeaxanthin, were shown to be useful indicators of the abundance and spatial distribution of certain phytoplankton groups. The relative contributions of the various phytoplankton groups to the total Chl a in the lake determined using these marker pigments were similar, but not identical, to those determined by cell counts. 3. Pigment analyses of isolated strains from Lake Baikal and some European lakes confirmed that phycoerythrin‐containing Cyanobacteria with very high amounts of zeaxanthin were responsible for the low Chl a/zeaxanthin ratios of the water samples. A picoplanktonic species of Eustigmatophyceae was isolated from the lake. Its high violaxanthin content, responsible for very low Chl a/violaxanthin ratios of some water samples, can be used to estimate the contribution of this group to total Chl a.     

NaCl胁迫对6种红花幼苗渗透调节物质及抗氧化系统的影响

采用沙培法,对红花（Carthamus tinctorius L.）6个品种幼苗进行不同浓度的NaCl胁迫处理,研究其叶绿素（Chl）、丙二醛（MDA）、可溶性糖（SS）含量及抗氧化酶（SOD、POD和CAT）活性的变化,并用隶属函数法对其耐盐性进行综合评定。结果表明：（1）随着盐浓度的增加,除封丘红花幼苗叶绿素含量逐渐下降之外,其它品种均呈先升高后降低的趋势;（2）盐胁迫下各种红花幼苗丙二醛和可溶性糖含量较对照均有显著增加,可溶性蛋白含量先增加后减少;（3）菏泽红花和川红花SOD活性在盐浓度为50mmol/L时与对照相比升高,随后下降,其它品种均呈下降趋势;NaCl胁迫下,6个红花品种POD和CAT活性都是先升高后降低;（4）应用隶属函数法,得出耐盐性的大小顺序为：封丘红花〉菏泽红花〉川红花〉亳州红花〉云红3号〉新疆红花。     

绥宁河生态修复对粒径分级叶绿素a的影响

通过对上海市的苏州河支流绥宁河治理段与非治理段水体叶绿素a分粒级分析,探讨了生态修复对水体粒径分级叶绿素a的影响．结果表明,非治理和对照以及治理采样点微型和微微型浮游植物叶绿素a占总叶绿素a的百分比均值分别为85．232、92．402和95．205％,其中微型浮游植物叶绿素a占总叶绿素a的百分比均值分别为78．460、87．943和87．211％,对全河叶绿素a的贡献平均为84．538％,是该水体叶绿素a生物量的最大贡献者;网采浮游植物对全河叶绿素a的贡献仅为9．054％．生态修复工程试验使网采浮游植物相对生物量减少,微型浮游植物相对生物量保持稳定,而微微型浮游植物相对生物量增多,对超微型浮游植物的影响不大,微型和微微型浮游植物对工程试验的反应最敏感．     

Assessment of phytoplankton class abundance using in vivo synchronous fluorescence spectra

In this study the feasibility of using the in vivo synchronous fluorescence spectra (SFS) of phytoplankton samples for determining the relative abundance of specific classes of phytoplankton was investigated. In total, 405 SFS of nine phytoplankton species cultivated under different conditions were measured and evaluated. First, principal component analysis (PCA) was used to obtain nine representative spectra, and three feature spectrum bands at 200-235, 310-335, and 355-585 nm of SFS were found to have a better discriminatory capability. The nine phytoplankton species were spectrographically sorted into six classes. Second, a relationship between the chlorophyll a (chla) concentration of phytoplankton extracts and the in vivo SFS intensity was found; thus the corresponding phytoplankton class abundance can be expressed by the concentration of standard chla. For this data set, the detection limit ranged 1.02-6.89 μg/L chla for different classes. Finally, qualitative and quantitative analyses of 30 mixtures of phytoplankton were carried out using the nonnegative least square regression (NNLS) method. The dominant phytoplankton classes could be identified while the qualitative recognition correctness rate was 88% and the quantitative standard deviation with fluorometrically determined chla was −0.14-0.04. Hence, it was possible to estimate the abundance of dominant phytoplankton classes.     

Addressing the trophic status in urban ponds: An evaluation of current trophic state indexes

Ponds are generally understudied. Quality problems in urban freshwaters can arise from eutrophication, and trophic status classification gives information related to their ecological situation. Ponds may strongly differ from larger lakes for which most current trophic status classification methods have been developed. This paper seeks to compare and contrast the suitability of six trophic status indexes (TSI) and OECD trophic classifications system currently used to evaluate the eutrophication level of urban ponds in the Subtropical region. The trophic status was evaluated based on total phosphorus (TP), soluble reactive phosphorus (SRP), total nitrogen (TN) and phytoplankton chlorophyll a (Chl a) in 12 ponds placed in different cities from the Pampean region (Argentina), in the warm and cold seasons. Our results demonstrate that there was no relationship between pond size (0.08–2.45 ha) and trophic status. TSIs estimated with Chl a showed significant differences between seasons and the range oligotrophic-hypertrophic of trophism was encountered. Conversely, TSIs estimated with nutrient concentrations (TP, SRP, TN) did not. The pond's classification in trophic levels fell in the eutrophic-hypertrophic extreme, and only considering TN/TP broadened the trophic range. No relationship was encountered between Chl a and P; however, Chl a and TN/TP were positively correlated during the warm season. Lower trophic levels regarding TSI (Chl a) were generally associated with a dense floating-macrophyte cover. We suggest that the TSI considered should correspond to the latitudinal region in which the ponds are located. Our results indicate that it appears restrictive to consider only P contents in ponds to assess eutrophication. Under the proposed framework, the key issues for the study of pond trophic classification will be to include not only P but N concentrations and TN/TP. Also, phytoplankton Chl a concentration jointly with floating macrophytes biomass/coverage should be considered as diagnosis parameters.     

Winter ecology of shallow lakes: strongest effect of fish on water clarity at high nutrient levels

While the structuring role of fish in lakes is well studied for the summer season in North temperate lakes, little is known about their role in winter when fish activity and light irradiance potentially are lower. This is unfortunate as the progressing climate change may have strong effects on lake winter temperature and possibly on trophic dynamics too. We conducted an enclosure experiment with and without the presence of fish throughout winter in two shallow lakes with contrasting phosphorus concentrations. In hypertrophic Lake Søbygård, absence of fish led to higher biomass of zooplankton, higher grazing potential (zooplankton:phytoplankton ratio) and, accordingly, lower biomass of phytoplankton and chlorophyll a (Chl a), while the concentrations of total nitrogen (TN), total phosphorus (TP), oxygen and pH decreased. The average size of egg-bearing Daphnia and Bosmina and the minimum size of egg-bearing specimens of the two genera rose. In the less eutrophic Lake Stigsholm, zooplankton and their grazing potential were also markedly affected by fish. However, the decrease in Chl a was slight, and phytoplankton biovolume, pH and the oxygen concentration were not affected. TN was higher when fish were absent. Our results indicate that: (i) there is a notable effect of fish on zooplankton community structure and size during winter in both eutrophic and hypertrophic North temperate lakes, (ii) Chl a can be high in winter in such lakes, despite low light irradiance, if fish are abundant, and (iii) the cascading effects on phytoplankton and nutrients in winter may be more pronounced in hypertrophic lakes. Climate warming supposedly leading to reduced winter mortality and dominance of small fish may enhance the risk of turbid state conditions in nutrient-enriched shallow lakes, not only during the summer season, but also during winter.     

模拟酸雨对白筋叶片抗氧化酶活性及叶绿素荧光参数的影响

采用棚内盆栽方法, 设置pH值5.6 （对照）、4.0、3.0和2.0的模拟酸雨胁迫试验, 探讨其对白簕幼苗叶片MDA含量、保护酶活性、叶绿素含量、气体交换参数和叶绿素荧光参数的影响。结果表明, 随着模拟酸雨pH值的降低, MDA含量呈先降低后升高的趋势; SOD活性逐渐降低, POD活性逐渐升高, APX活性呈先升高后降低的变化。叶绿素a、叶绿素b、总叶绿素含量均比对照高, 在pH 4.0时达最大值。气孔限制值（Ls）、PSII实际光化学量子产量（ΦPSII）、光化学淬灭系数（qP）均随pH值的降低而下降, 净光速率（Pn）、气孔导度（Gs）、蒸腾速率（Tr）、水分利用效率（WUE）、PSII最大光化学效率（Fv/Fm）、PSII的潜在活性（Fv/Fo）、非光化学淬灭系数（qN）呈先升高后降低趋势, 且也都在pH 4.0时达最大值。由此推测, pH 4.0的酸雨处理有利于白簕幼苗的生长, 表明白簕幼苗可能喜欢生活在微酸环境中, 但是随着酸度加强, 反而起到抑制作用。     

三疣梭子蟹两种养殖模式浮游植物与产量的比较

为获知三疣梭子蟹（Portunus trituberculatus）两种养殖模式浮游植物与产量是否存在差异,于2012年6月—12月在宁波市象山县东盛水产养殖有限公司进行。结果显示：浮游植物共7门32属57种。模式Ⅰ浮游植物7门30属54种;模式Ⅱ5门19属32种。藻类平均细胞密度、平均生物量均为模式Ⅰ〉模式Ⅱ。Margalef指数、Shannon-Wiener指数均值模式Ⅰ〉模式Ⅱ,Pielou指数均值模式Ⅰ〈模式Ⅱ。养殖前期（8月）、中期（10月）、起捕（12月）时,对三疣梭子蟹壳长、壳宽、体重测量取其平均值,均为模式Ⅰ〉模式Ⅱ。三疣梭子蟹产量模式Ⅰ〉模式Ⅱ。研究表明,模式Ⅰ优于模式Ⅱ。     

Remote sensing of chlorophyll in Lake Kinneret using highspectral-resolution radiometer and Landsat TM: spectral features of reflectance and algorithm development

High-resolution reflectance spectra in the range of 400–850nm were obtained from Lake Kinneret during a period when densepopulations of the dinoflagellate Peridinium gatunense dominatedthe phytoplankton. Chlorophyll (Chl) concentrations ranged from5.1 to 185 mg m^–3 and from 2.4 to 187.5 mg m^–3 inthe samples of two independent experiments. The most prominentfeatures of the reflectance spectra were: (i) a wide minimumfrom 400 to 500 nm; (ii) a maximum at 550–570 nm, whichdid not surpass 3% in samples with high Chl concentration (>20mgm^–3), indicating a strong absorption by pigments in thegreen range of the spectrum; (iii) a minimum at 676 nm; thiswas {small tilde}1% and was almost insensitive to variationin Chl concentration >10 mg m^–3; (iv) a maximum reflectanceshowed near 700 nm; its magnitude and position were highly dependenton chlorophyll concentration. High-spectral-resolution datawere used as a guideline for selection of the most suitablespectral bands for chlorophyll remote sensing. Models were devised,based on the calculation of the integrated area above the baselinefrom 670 to 850 nm and the reflectance maximal height withinthis range. Some algorithms already used m previous studieswere tested and showed a plausible degree of accuracy when appliedto the current data base. However, novel models devised in thisstudy improved substantially the accuracy of Chl estimationby remotely sensed data, by reducing the estimation error from>11 to 6.5 mg m^–3 Those models were validated by anindependent data set where Chl concentration ranged over twoorders of magnitude. The use of three relatively narrow spectralbands was sufficient for Chl mapping in Lake Kinneret. Therefore,a relatively simple sensor, measuring only a few bands willbe employed in future applications for Chl monitoring in inlandwaters. Radiometric data were also used to simulate radiancesin the channels of TM Landsat and to find the algorithm forChl assessment. The ratio of channel 4 to channel 3 was usedand enabled Chl estimation with an error of <15mg m^–3This algorithm was employed to map Chl in the entire area ofLake Kinneret with 10 gradations.     

Size-fractionated Primary Production in the South Atlantic and Atlantic Sectors of the Southern Ocean

Results are presented from size fractionated chlorophyll a (Chla) and primary production studies along a transect between Antarcticaand southern Africa during the second South African AntarcticMarine Ecosystem Study (SAAMES II), conducted in late australsummer (January to February) 1993. Total integrated Chl a alongthe transect was highest in the vicinity of the Marginal IceZone (MIZ) and Antarctic Polar Front (APF). At these stations,integrated Chl a biomass was always >25 mg Chl a m^–2and was dominated by microphytoplankton. Although nominal increasesinChl a biomass were also associated with the Subantarctic Front(SAF) and Subtropical Convergence (STC), total Chl a biomassin these regions was dominated by nanophytoplankton. Withinthe inter-frontal regions, total integrated Chl a biomass waslower, generally <25 mg Chl a m^–2, and was always dominatedby nanophytoplankton. An exception was found in the AgulhasReturn Current (ARC) where picophytoplankton dominated. Totaldaily integrated production along the transect ranged between60 and 436 mg C m^–2 day^–1. Elevated production rateswere recorded at stations occupied in the vicinity of the MIZand at all the major oceanic frontal systems. The contributionsof the various size fractions to total daily production displayedthe same spatial pattern as integrated biomass, with microphytoplanktonbeing the most important contributor in areas characterizedby elevated phytoplankton biomass. Outside these regions, nanophytoplanktondominated the total phytoplankton production. Again, an exceptionwas found in the ARC north of the STC where picophytoplanktondominated total production. There, the lowest production alongthe entire transect was recorded, with total daily integratedproduction always <90 mg C m^–2 day^–1. The increasedproduction rates recorded in the MIZ appeared to result fromincreased water column stability as indicated by a shallow mixed-layerdepth. Within the inter-frontal regions, the existence of adeep mixed layer appeared to limit phytoplankton production.Low silicate concentrations in the waters north of the APF mayalso have limited the growth of large microphytoplankton.