Effects of an Artificial Breakwater on the Distributions of Planktonic Microbial Communities

The summer distributions of planktonic microbial communities (heterotrophic and phtosynthetic bacteria, phtosynthetic and heterotrophic nanoflagellates, ciliate plankton, and microphytoplankton) were compared between inner and outer areas of Lake Sihwa, divided by an artificial breakwater, located on the western coast of Korea, in September 2003. The semienclosed, inner area was characterized by hyposaline surface water (<17 psu), and by low concentrations of dissolved oxygen (avg. 0.4 mg L¹) and high concentrations of inorganic nutrients (nitrogenous nutrients >36 μM, phosphate <4 μM) in the bottom layer. Higher densities of heterotrophic bacteria and nanoflagellates also occurred in the inner area than did in the outer area, while microphytoplankton (mainly diatoms) occurred abundantly in the outer area. A tiny tintinnid ciliate, Tintinnopsis nana, bloomed into more than 10⁶ cells L¹ at the surface layer of the inner area, while its abundance was much lower (10³-10⁴ cells L¹) in the outer area of the breakwater. Ciliate abundance was highly correlated with heterotrophic bacteria (r = 0.886, p < 0.001) and heterotrophic flagellates (r = 0.962, p < 0.001), indicating that rich food availability may have led to theT. nana bloom. These results suggest that the breakwater causes the eutrophic environment in artificial lakes with limited flushing of enriched water and develops into abundant bacteria, nanoflagellates, and ciliates.     

春季西沙永乐龙洞浮游植物的昼夜垂直分布特征

南海永乐龙洞位于西沙群岛永乐环礁,是迄今为止发现的最深的海洋蓝洞,水文环境及理化因素特殊,90 m以下水体为无氧环境。为研究永乐龙洞浮游植物的群落组成及其昼夜变化,于2017年3月在龙洞、潟湖及外礁坡进行浮游植物样品采集。研究结果表明:龙洞内叶绿素a浓度呈现随深度先增大后减小的趋势,日间浓度最大值层出现在40 m层(0.42μg/L),夜间则出现在20 m层(0.59μg/L)。永乐龙洞微微型浮游植物丰度介于1.1×10^3~5.1×10^4 cells/mL。聚球藻在上层水体占优势(0~20 m),40 m以下水层原绿球藻丰度对微微型浮游植物丰度贡献率最大(90%以上),微微型真核浮游植物丰度在整个水体都较低(除20 m层)。微微型浮游植物昼夜存在明显差异,夜间其丰度最大值层为20 m层,日间则上移至表层。本研究共记录微型和小型浮游植物5门41属55种(含未定种)。其中,硅藻门25属34种、甲藻门12属15种、金藻门1属1种、蓝藻3属、隐藻1属。微型和小型浮游植物丰度介于3.3×10^2~9.8×10^4 cells/L。甲藻丰度对浮游植物总丰度贡献率最大,其次是硅藻,隐藻和蓝藻丰度仅在少数水层占优势。微型和小型浮游植物昼夜变化明显,夜间丰度最大值层为20 m层,日间则出现在40 m层。微微型、微型和小型浮游植物垂直分布与叶绿素a浓度垂直分布一致性高。龙洞浮游植物的种类数和丰度高于潟湖和外礁坡。     

南极布兰斯菲尔德海峡及象岛邻近水域小型浮游植物的分布特征研究

本文分析研究了布兰斯菲尔德海峡及象岛邻近水域小型浮游植物的种类组成、数量分布、群落结构及其与环境因子的关系,共鉴定了小型浮游植物54属201种,平均细胞丰度为4406×10~3个/m~3,大部分为硅藻类,数量最大的为扭链角刺藻、长形环毛藻、克革伦氏菱形藻和翼根管藻等种类。小型浮游植物最高丰度分布在南设得兰群岛近岸、陆架水域,这是由近岸冷水性的小型浮游植物群落组成。小型浮游植物的密度与硅酸盐浓度呈正相关(r=0.438,n=28,P<0.05)。     

南极普里兹湾及其毗邻南印度洋夏季微小型浮游植物的分布特征

1990年 1 2月～ 1 991年 1月从南极普里兹湾及其毗邻南印度洋获得的微小型浮游植物样品 ,经鉴定、分析表明 :调查海区有 5门 40属 1 2 2种、变种和变型 ,其中硅藻类占 73 .0 %,甲藻类占2 0 .5 %,其它仅占 6 .5 %。表层水样微小型浮游植物平均丰度为 2 5 5 1× 1 0 4个 /m3 ,其密集区主要分布在普里兹湾内邻近陆架区的 7站和西冰架与沙克尔顿冰架之间的以北海域 ( 3、 4、 2、 3、 1站及 1站 ) ;位于普里兹湾西北部海域断面 和 1～ 5站丰度最低。网采浮游植物平均丰度为 81 2× 1 0 4 个 /m3 ,其密集区则分布在普里兹湾邻近陆架区 ( 2、 4、 5、 7、 4、 5站 )和西冰架北部海域 ( 1、 3站 ) ;低丰度位于沙克尔顿冰架东部海域 (断面 、 的测站 )。微小型浮游植物垂直分布密集区位于测区中部 ( 3、 3站 )和东部 ( 3站 ) 0～ 5 0 m水体 ,水深1 0 0 m以下至 2 0 0 m随深度的增加而丰度逐渐减少。微小型浮游植物丰度与大磷虾的丰度和营养盐 (N、P、Si)浓度成显著的负相关。     

Distribution of the plankton assemblages during the winter and summer along the southern coast of the Kerkennah Islands (Tunisia,Eastern Mediterranean Sea)

We studied the distribution of microphytoplankton, ciliates and mesozooplankton in relation to environmental factors in the coastal waters around the Kerkennah Islands. Diatom species were more abundant in winter, representing 74% of the total microphytoplankton abundance, whereas dinoflagellate abundance was higher in summer (58%). Naked ciliates dominated during the winter (73%) and loricate ciliates dominated during the summer (67%). Copepods were the most abundant mesozooplankton group present during the entire period of study, comprising 93%–98% of the total mesozooplankton community. The results indicate that (i) species distribution differed significantly between winter and summer, (ii) environmental factors such as temperature, salinity and nutrients influenced plankton assemblages; and (iii) the highest abundance of several pollution indicator species was due to direct exposure to the polluted coast of Sfax and the effect of tidal asymmetries generating nutrient‐rich inputs from the city.     

浙江舟山群岛邻近海域微,小型浮游植物与赤潮生物研究

报道了舟山群岛邻近海域未发生赤潮与发生赤潮时的微、小型浮游植物组成、数量分布、赤潮生物种类与环境的关系。舟山群岛邻近海域共有浮游植物 1 69种 ,其中赤潮生物为 59种。赤潮发生时比未发生赤潮时水域的浮游植物密度高 1 0～ 1 0 0个 /dm3,浮游植物密度与硅酸盐、硝酸盐浓度成负相关 ,与溶解氧和透明度成正相关。平均浮游植物密度 :春季表层水样为4.5× 1 0 4 个 /dm3,底层水样为 5.2× 1 0 3个 /dm3,网样为 2 .7× 1 0 5个 /m3;秋季网样为 3.7× 1 0 6个 /m3。表层水样的赤潮生物优势种 :春季为微型的三鳍原甲藻 ,平均细胞密度为 3.3× 1 0 5个/dm3,占总细胞密度的 77.2 % ;秋季为微型的中肋骨条藻 ,平均密度为 2 .7× 1 0 3个 /dm3,占总细胞密度的 72 .2 %。三鳍原甲藻、海洋原甲藻、夜光藻等为浙江舟山群岛邻近海域常见的有害赤潮生物。