Environmental influence on phytoplankton production during summer on the KwaZulu-Natal shelf of the Agulhas ecosystem

During February 2010, studies of primary production (PP) and physiology were conducted at five selected sites in the KwaZulu-Natal (KZN) Bight of the Agulhas ecosystem as part of a programme to elucidate the influence of major physical driving forces and nutrient inputs on the structure and functioning of biological communities. These sites were located in the vicinity of the Durban lee eddy, in the midshelf region of the central part of the bight, off the Thukela Mouth, and to the north and south of Richards Bay. At four of the sites, chlorophyll a ranged from 0.10 to 1.44?mg m–3 and integrated PP ranged between 0.35 and 2.58?g C m–² d–1. The highest biomass and PP, which were comparable to those observed in a wind-driven upwelling system, were associated with a diatom community observed at the midshelf site, and varied between 0.26 and 4.27?mg m–³ and 7.22 and 9.89?g C m–² d–1, respectively. Environmental conditions at each of the sites differed substantially and appeared to be influential in initiating and controlling the development and distribution of phytoplankton biomass and production. Phytoplankton adaptation to variable environmental conditions was characterised by a decreased light-limited slope (αB) and increased rate of photosynthesis (P_m ) and light saturation (Ek) with elevated temperatures. The converse (increased α^B and decreased P_m and Ek) was observed as irradiance levels declined. Generalised additive models indicated that irradiance, temperature and biomass were important variables influencing photosynthetic parameters and photosynthetic rates.     

春、秋季考洲洋海水质量状况及评价方法初探

文章利用2017年11月（秋季）和2018年4月（春季）对惠州考洲洋海域开展的两个航次水环境调查数据,分析了考洲洋海域表层溶解氧（DO）、化学需氧量(COD)、无机氮(DIN)、无机磷(DIP)和石油类（OIL）等典型水质因子的水平分布和季节变化情况。结果表明,秋季溶解氧、化学需氧量、石油类分别在盐洲岛以东附近海域、考洲洋湾顶海域和盐洲岛东南海域出现高值区,而无机氮在整个考洲洋无明显区域分布差异,无机磷含量呈现考洲洋内湾到湾口逐渐递减的趋势;春季化学需氧量、无机磷均在考洲洋湾顶出现高值区域,无机氮在盐洲岛以东附近海域出现高值区,而溶解氧和石油类无明显变化。从季节变化来看,秋季考洲洋海域溶解氧、化学需氧量和石油类平均含量均比春季高;无机氮、无机磷则相反,平均含量秋季低于春季。同时,文章还分别利用单因子和综合因子方法对海水有机污染状况进行评价并对其进行比较分析,结果表明,有机污染评价指数法可充分考虑多种水质因子,更适合对考洲洋水环境质量进行评价,得到较为客观的综合评价结果。     

三亚湾夏秋两季微型浮游动物摄食研究

根据2005年8月和11月的调查资料,利用现场稀释法,以叶绿素a为检测对象,分别对三亚湾海区夏秋两季微型浮游动物的摄食情况进行研究。结果表明,夏秋两季浮游植物瞬时生长率(k)分别为0.9~1.32/d和1.81~3.30/d,而微型浮游动物的摄食率(g)则为0.85~1.79/d和1.29~2.57/d。对浮游植物现存量和初级生产力的摄食压力分别是,夏季为57.26%~83.30%和78.13%~140.38%,秋季为72.47%~92.35%和86.65%~97.90%。秋季微型浮游动物以微型浮游植物为其主要食物来源,其摄食率和对初级生产力的摄食压力最高,平均分别为1.09/d和107.98%;微型浮游植物的瞬时生长率也是最高的,平均为0.94/d,为浮游植物群体的主要组成部分。在三亚湾夏秋两季可把微型浮游动物作为控制浮游植物生长的重要影响因子之一,同时与秋季相比,夏季微型浮游动物在物质循环和能量流动方面起到更显著的作用。     

Species composition,abundance and biomass of microphytoplankton in the KwaZulu-Natal Bight on the east coast of South Africa

Nearshore marine environments are influenced by an array of variables that can either be land-derived or of marine origin, and nearshore phytoplankton communities may differ in their taxonomic composition and biomass in response to such variables. The KwaZulu-Natal Bight (hereafter referred to as ‘the bight’) is an oligo-mesotrophic, nearshore oceanic environment, that is influenced by both terrestrial run-off and upwelling. A microphytoplankton survey of the bight conducted over several stations and depths and two seasons was conducted in order to ascertain species composition, abundance and biomass. Microphytoplankton abundance was generally low (a maximum of 180 000 cells l–1 was recorded) but differed considerably between sites and seasons. A total of 99 taxa of mainly Bacillariophyceae and some Dinophyceae, Prymnesiophyceae and Cyanophyceae were identified in the present study. In the central bight, higher abundance and biomass were measured in February (wet season), which may be a possible consequence of terrestrial nutrient inputs. In the northern and southern bight we measured higher abundance and biomass in August (dry season). Upwelling was not detected during the study, but an influence of terrestrial nutrient sources was detected at the coastal stations. Turbid conditions were specific to the site near the Thukela River mouth and possibly influenced abundance, biomass and species composition at this site. Historic data on microphytoplankton composition are scarce, but comparisons with surveys from the 1960s reveal that around 60% of the common diatoms recorded then also occurred in the present study. Small taxa [20–200 µm] dominated the microphytoplankton community. Community composition was fairly uniform throughout the bight in both seasons, dominated in general by Chaetoceros species, and on occasion co-dominated by Thalassionema nitzschioides and Dactyliosolen fragilissimus.     

大亚湾浮游植物粒级结构和种类组成对淡澳河河口水加富的响应

人类活动引起的营养物质输入导致大亚湾出现海水富营养化、赤潮频发和生物多样性下降等生态问题。为探究陆源输入影响下大亚湾湾顶淡澳河输入对湾内浮游植物粒级结构和种类组成的影响, 2016年10月在大亚湾进行了原位观测和培养试验。原位观测结果显示, 淡澳河口的总溶解态氮、磷浓度分别达到85.3μmol·L^-1和1.5μmol·L^-1。加富培养试验结果表明, 淡澳河河口水加富对总叶绿素a (Chl a)和总浮游植物丰度有显著促进作用, 并导致浮游植物粒级结构由小粒级Chl a (0.7~20μm)占主导; 浮游植物丰度中甲藻比例升高, 主要种类为锥状斯氏藻(Scrippsiella trochoidea)和原甲藻(Prorocentrum spp.)。同样, 尿素加富也促进了浮游植物群落中小粒级Chl a和甲藻的比例增加, 且主要甲藻种类与河口水加富结果一致。无机氮、磷同时加富促进了总Chl a和浮游植物总丰度增加, 而对浮游植物粒级结构和甲藻丰度则没有明显影响。对照河口水和氮、磷营养盐加富试验结果, 说明河口水携带的溶解性有机氮源可能是导致大亚湾浮游植物群落小型化, 促进甲藻生长的关键营养盐形态, 其携带的无机氮、磷同时促进总浮游植物丰度增加。本研究结果表明有机形态营养组分对大亚湾富营养化和有害藻华可能产生重要影响。     

基于反相C8色谱柱的海洋浮游藻色素高效液相色谱分析方法有效性验证

对一种海洋浮游藻色素高效液相色谱分析方法进行了有效性验证。该方法使用反相C8色谱柱,以甲醇、乙腈和丙酮为流动相,并在流动相中添加吡啶/醋酸溶液作为修饰剂改善色素峰的分离效果。结果表明,4种色素标准在一定的浓度范围内线性关系良好,叶绿素a的线性范围为189.6~18 960μg/L,叶绿素b为89.2~8 920μg/L,β,β-胡萝卜素为7.77~777.2μg/L,叶黄素为15.28~1 528μg/L。除β,β-胡萝卜素外各色素标准的回收率在不同浓度下均在90%以上,相对标准偏差也普遍低于5%。在4个参考藻种和123个胶州湾现场样品中共检测出37种色素,一些关键的特征色素均获得了良好的分离效果。该方法操作简便,具有分离度好、灵敏度高、重复性好、回收率高等优点,适用于培养的藻种和现场样品中的海洋浮游藻色素分析。     

Winter phytoplankton assemblages of coastal Yellow Sea connected to Jiaozhou Bay, China

I Introduction Phytoplankton play an important role in the primary production of ocean (Ning et al., 1995). They are impor-tant biological mediators of carbon turnover in seawater ecosystems (Zhu et al., 1993). Phytoplankton in Jiaozhou Bay have been preliminarily studied on the subjects of community structure, primary productivity and carbon budget (Qian et al., 1983; Guo et al., 1992; Jiao et al., 1994). It has been found that seasonal variation of phytoplankton cell abundance presents w…     

2010—2012年青岛海滨浴场67周次浮游植物的群集特征

2010—2012年对青岛汇泉湾海滨浴场区2站点的浮游植物及环境因子进行67周次连续监测,共检出浮游植物53属94种,细胞总丰度的变化范围为7.19~272.35个/mL,均值为46.74个/mL,硅藻在细胞总丰度中的比例平均达70.34%,主要优势种有骨条藻、角毛藻、菱形藻、新月筒柱藻和舟形藻。调查期内,共检到3次硅藻的赤潮,未检到营养盐发生限制的现象。周年的统计分析显示,调查区浮游植物群落中的羽纹硅藻类与营养盐呈显著的相关关系(P0.05)。在浴场开放期,Chl-a质量浓度均值达7.26mg/L,为全年最高,浮游植物群落以羽纹硅藻类最占优势,并且Chl-a与羽纹硅藻丰度呈现极显著的正相关(P0.01)。特别对羽纹硅藻在开放期占优势可能引发的不利影响作了探讨,并建议在今后监测和评价该类休闲水域时,应对此给予重视。     

Construction and screening of a functional metagenomic library to identify novel enzymes produced by Antarctic bacteria

A metagenomic fosmid library of approximately 52 000 clones was constructed to identify functional genes encoding cold-adapted enzymes. Metagenomic DNA was extracted from a sample of glacial meltwater,...