Toxic effect of dinoflagellate Alexandrium species on Cladocera Moina mongolica Daday

The main objective of this study was to investigate toxic effects of the dinoflagellate Alexandrium species, on cladocera Moina mongolica in the laboratory. Ten strains of Alexandrium species, including Alexandrium tamarense （AT-6, ATHK, ATCI02, ATCI03 and AT5-1）, A. catenella （ACDH）, A. affine （AC-1 and AS-1）, A. lusitanicum and A A. tamarense （ATHK, ATCI02 and AT5-1） and A minutum were tested. The results showed that affine （AC-1 and AS-1）, but not A. tamarense （AT-6 and ATCI02）, A. catenella （ACDH）, A. lusitanicum and A. minutum had significantly negative effects on the survival of M. mongoliea; when exposed to these ten strains of Alexandrium species in densities of 3 000 cells/cm^3 for 7 d, respecyively. M. mongolica could feed on A. tamarense （AT-6, ATHK, ATCI02, ATCI03 and AT5-1）, A. eatenella, A. lusitanieum and A. minutum, but exhibited little or no grazing on A. affine （AC-1 and AS-1）, based on the changes in gut pigment af- ter exposure to alga for 1 and 12 h. A. affine AC-1, which had the strongest toxicity on the survival of M. mongolica, was chosen to further study the negative effects on M. mongolica. The results showed that the effect of A. affine AC-1 on the survival of M. mongolica was density-dependent, and its lethal effects on one-day, two-day and three-day old M. mongolica were exacerbated with increasing age; The whole algal culture, re-suspended algal cells, cell fragments and cell contents all had adverse impacts on the survival of M. mongolica. Moreover, both juvenile numbers and life-span time of M. mongolica were decreased significantly when they were cultured in A. affine AC-1 of 10 and 50 cells/cm^3, combined with 3×10^6 cells/cm^3 of Chlorella spp., respectively. As a non-PSP producer, A. affine may produce other toxins, responsible for the strong negative effects on M. mongolica.

2001—2020年天津近岸海域赤潮特征分析

文章通过对2001—2020年天津近岸海域发生的赤潮进行统计分析发现,近年来天津近岸海域赤潮发生呈现高频次小规模的特征。2012—2020年赤潮年度累计持续天数大体呈增加趋势,这主要是受DIP控制。夏季是赤潮高发期,尤其是6月和8月,单次赤潮过程持续时间较长。天津近岸海域赤潮肇事种主要是夜光藻、中肋骨条藻和尖刺伪菱形藻,这3种藻类在时间上有交替成为肇事种的特征,这主要与它们对水文环境的适应性相关。有毒赤潮主要集中在6—9月暴发,9月暴发的赤潮多为有毒赤潮,天津近岸海域有毒赤潮种多为多环旋沟藻和米氏凯伦藻。

我国东海常见6种有毒赤潮藻的三维荧光光谱识别技术

基于有毒赤潮藻的三维荧光光谱及主成分分析方法,针对我国东海常见的6种有毒赤潮藻建立了有毒赤潮藻活体荧光识别测定技术。根据Fisher判别分析结果,选用三维荧光光谱的第一主成分得分谱作为有毒赤潮藻识别特征谱,建立了有毒赤潮藻荧光特征库,在此基础上,利用非负最小二乘法对6种有毒赤潮藻进行识别测定,有毒赤潮藻的识别正确率≥80%。

近十年福州沿海赤潮的基本特征研究

收集统计了2008—2017年的福州沿海赤潮记录历史资料,对近十年福州沿海赤潮的基本特征进行综合分析,结果表明:(1)2012年赤潮发生的次数最多,2010年赤潮发生的面积最大。近五年(2013—2017年)与之前五年(2008—2012年)相比,赤潮的年发生次数、持续天数和发生面积都呈明显减少的趋势;(2)赤潮的发生期为3—9月,高发期为5—6月;(3)赤潮主要发生在黄岐半岛沿海、闽江口沿海、长乐沿海、福清湾-海坛海峡海域和罗源湾海域,大部分发生在黄岐半岛沿海。封闭型和半封闭型海域发生的赤潮较多,不同藻类的空间分布存在较明显的区域特征;(4)引发福州沿海赤潮的藻种有8种,分别是东海原甲藻、中肋骨条藻、米氏凯伦藻、夜光藻、柔弱拟菱形藻、圆海链藻、刚毛根管藻和丹麦细柱藻,其中前3者为主要影响种,作为其中唯一的有毒藻种,米氏凯伦藻虽然在发生次数、持续天数和发生面积上占比均不大,但是近十年福州沿海几乎所有由赤潮灾害导致的重大渔业经济损失均与其有关。

三种材料的抑藻效果及其毒性研究

研究了3种天然抑藻材料对塔玛亚历山大藻的抑制作用以及其对卤虫、轮虫的毒性效果。绿茶粉末、小叶桉种子粉末及生姜糜对该藻均有很好的抑制效果,其中,在快速抑藻方面(5 h),生姜糜优于其它两种材料,1.0 g/L的浓度抑藻率即高达95.6%,大于同浓度绿茶粉末的抑藻率(89.7%)、小叶桉种子粉末的抑藻率(65.0%);生姜糜的有效抑藻浓度也最低,3种材料对赤潮藻ATDH01的48 h半抑制浓度分别为:生姜糜0.33 g/L、绿茶粉0.44 g/L、小叶桉种子粉末0.56 g/L;在对卤虫的毒性方面,各材料对卤虫的96 h-LC50分别为:生姜糜0.80 g/L、绿茶粉0.28 g/L、小叶桉种子粉末0.30 g/L;在对轮虫的毒性方面,小叶桉种子粉末对轮虫的96 h-LC50为1.44 g/L,生姜糜和绿茶粉对轮虫96 h-LC50则分别为0.915 g/L、0.224 g/L.生姜糜的效用-安全比为0.545,要小于绿茶粉(1.781)和小叶桉种子粉(0.582 5);从抑藻率、有效抑藻剂浓度、成本等多方面考虑,生姜糜是最佳的抑藻剂材料。