Effect of using Spirulina and Chlorella as feed additives for elevating immunity status of Nile tilapia experimentally infected with Aeromonas hydrophila

The present trial was performed to evaluate the effect of dietary incorporation of dried Spirulina, Chlorella and their mixture on the immune status of Nile tilapia (Oreochromis niloticus) before and after artificial infection with pathogenic bacterium Aeromonas hydrophila (A. hydrophila). Two hundred and forty fish were divided into four groups: (a) a control group fed on a basal diet only, (b) a second group fed on a diet containing Spirulina 15%, (c) a third group fed on a diet containing Chlorella 15%, and (d) a fourth group fed on a diet containing a mixture of both Spirulina 15% and Chlorella 15%. At the end of the experiment (9 weeks), the four groups were experimentally infected with A. hydrophila for 7 days. Antioxidant enzymes, lysozyme and bactericidal activities and histopathological changes were determined just before the challenge test and 7 days post‐challenge. Significant (p ≤ 0.05) increases in fish body protein% before the challenge test and increases in serum antioxidant enzymes, lysozyme and bactericidal activity in the Chlorella and algal mixture groups before and after the challenge test were observed. Spirulina, Chlorella and their mixture groups significantly decreased serum malondialdehyde compared to the control group before and after the challenge test. Using Spirulina, Chlorella and their mixture mitigated the necrotic and degenerative changes induced by A. hydrophila and revealed well‐developed and multiple melanomacrophage centres. Thus, dietary Spirulina, Chlorella and their mixture inclusion in Nile tilapia fish proved to have a protective effect against A. hydrophila infection.     

安康水库水环境现状研究

研究安康水库水质与水生生物,为南水北调水源地的水质保护和渔政管理提供参考。在瀛湖库区设7个采样点,2015年7月-2016年6月每月1次、2016年8月-2017年6月每2个月1次采集水样,检测水质与藻类。结果显示,安康水库水体透明度在1.2m以上,12月份最高,3.5m;pH7.38～8.50,中性偏碱;溶解氧10.46mg/L;高锰酸盐指数(CODMn)与5日生化需氧量指数(BOD5)6-8月份最高,12-2月份较低,总体符合地表水I类水质标准;Cl-、Mg2+、Ca2+、SO2-4等的含量及水体总硬度均符合I类水质标准。水库藻密度最高值出现在4月,最低值在12月,分别为3.49×10~6个/L与0.07×10~6个/L,全年藻密度均值为0.8×10~6个/L。安康水库水质大部分时间内为I类水,水质总体状况优良,冬季的水质优于春夏季。     

藻际微环境中藻体与微生物相互作用

藻类与藻际微环境中的微生物紧密关联,存在极为复杂的关系。为了研究藻-菌互作机制,实现藻体的高效培养、污水处理、赤潮治理等,重点从藻-菌基本营养物质依赖、活性物质相互作用、信息交流三个方面总结了它们之间的复杂关系,并对在研究过程中需要解决的问题做出了展望。     

基于MaxEnt模型预测极北海带在我国黄渤海的适生情况

我国黄渤海区域的自然藻场存在不同程度的退化,建立人工藻场是制止海底荒漠化、恢复海底植被和建设海洋牧场的重要手段。本研究模拟极北海带(Laminaria hyperborea)在我国黄渤海区域的适生情况,使用MaxEnt生态位预测方法,针对影响极北海带分部的21项关键水质及水文条件以及在原产地的分布情况,建立我国黄渤海海域生态位分布模型,划分相应的适生区域,并通过刀切法筛选对模型贡献度较大的环境因子,逐一分析其对极北海带适生性的影响。结果显示,在筛选出的9项对模型贡献度较大的环境因子中,温度与光照强度对极北海带分布的影响最大。极北海带在温度7℃～18℃范围、光强不超过52 E/(m2·d)的区间有较大的适生概率;氮、磷浓度对预测结果也有一定影响,但天然海水中的氮、磷浓度不足以成为极北海带分布的限制因子。总体来看,黄渤海区域有1.67%海域为中适生区,主要集中在辽东半岛东岸长海县附近海域;山东半岛东部、北部,渤海西北部有一定的低适生范围,占总海域面积的5.12%;非适生区和边缘适生区占海域总面积的88.51%和4.70%。本研究表明,辽东半岛东岸长海县附近海域是建立极北海带藻场的理想区域。     

溪流生态系统中生物体脂肪酸对环境变化的响应及其在生态健康评价中的应用前景

全球溪流生态系统受人类活动的影响日益加剧,其健康受到了严重威胁。寻找一种综合简便的健康评价的指示物对溪流生态系统的健康评价、保护和管理至关重要。脂肪酸是参与生物体营养物质代谢的重要小分子化合物,是主要能量物质之一。生态系统中脂肪酸的可获得性因初级生产者不同而存在差异,部分脂肪酸在营养级之间的迁移转化具有很好的保守性,并且生物体脂肪酸组成与含量对环境变化的响应敏感,使得其在河流健康评价中有着潜在的应用前景。本文首先介绍了脂肪酸的命名规则、分类方式、合成途径及重要生理功能;其次,详细描述了溪流生态系统中底栖藻类、浮游生物、大型底栖无脊椎动物和鱼类等脂肪酸样品的采集、预处理及测定方法;归纳了这几种生物类群中脂肪酸组成及含量对外界各环境因素变化的响应;最后,总结了以初级生产者中的脂肪酸组成作为生态系统健康评价生物指示物的可行性,简析了应用消费者中的脂肪酸来指示生态健康变化较少的原因,提出了以生产者（藻类）脂肪酸评价溪流生态健康的方法体系及发展方向。     

海水单胞藻培养液中微量元素的最佳浓度↑（*）

本文通过正交试验,研究确定了铜、锌、锰、钼、钴、镍为牟氏角毛藻（Ｃｈａｅｔｏｃｅｒｏｓｍｕｌｅｒｉ）和金藻（Ｉｓｏｃｈｒｙｓｉｓｇａｌｈａｎａ）培养的必需元素,并确定了最佳浓度,依次为（１～５）×１０－８、１０－９、（５～１０）×１０－８、（１～５）×１０－８、１０－７～１０－９、１０－９ｍｏｌ／Ｌ。它们应用于牟氏角毛藻和金藻的培养,可使细胞浓度和叶绿素浓度分别提高２０４％～４３２％和１９７％～２５６％。本文的研究结果较著名的Ｍ－ｆ／２配方增加了镍,并对其他的五种元素的浓度进行了修订。铜、钼、钴的浓度和Ｍ－ｆ／２配方基本相同;锰的浓度低约１个数量级;锌的浓度低约２个数量级。     

苦草-附着生物复合系统对水体磺胺降解的贡献评估

磺胺类抗生素（Sulfonamides，SAs）在医药和养殖领域的广泛使用，造成自然水体中残留量不断增加，对水生态系统造成严重危害。为此，本研究选择沉水植物苦草（Vallisneria natans）作为实验物种，设置P-V-（无附着生物，无苦草）、P+V-（有附着生物，无苦草）、P-V+（无附着生物，有苦草）、P+V+（有附着生物，有苦草）四种处理，开展静态模拟试验，探讨了沉水植物-附着生物复合系统对磺胺（Sulfonamide，SN）降解效果及各自的贡献。结果表明：在降解水中SN的过程中，P+V+处理组SN浓度由25 mg·L-1降至5.4 mg·L-1，其SN去除率为78.4%，P+V+处理组SN降解效果最好；实验13d时苦草的贡献率为94.34%，发挥着主要作用，附着生物的贡献率为5.66%，起到次要作用；丛毛单胞菌科、细胞弧菌科和腐螺旋菌科为P+V+处理组附着生物的优势类群。本研究结果有助于了解苦草-附着生物复合体对SN降解效果以及苦草和附着生物对SN降解的贡献，对后期研究附着生物的定植演替规律和群落结构特征以及应用“沉水植物-附着生物复合系统”来治理抗生素污染水体提供理论支撑。     

松桃河锰行业聚集区河流丝状藻的分布和锰富集特征

摘要：电解锰行业较聚集的松桃河流域锰污染问题突出，但其水生生态系统的风险尚不明确。本文根据现场调研和监测，了解了松桃河主要藻类的分布和生长情况，并对松桃河的水质指标、底泥和藻类的金属含量进行了研究和数据分析。结果发现：松桃河有藻类聚集生长的区域较少，主要在部分河水流速较缓、周边有居民区的受污染河段发现了附着在河底石块上生长茂盛的水绵属（Spirogyra）和刚毛藻属（Cladophora）丝状藻群落；松桃河水体中的主要污染物为氨氮和锰，流经锰聚集区的河段超标情况明显，丝状藻和底泥的Mn含量均较高且呈现出明显的空间差异，但两者的金属元素含量特征存在明显的差异，丝状藻呈现出对金属离子选择性的累积，特别是对Mn的累积能力较强，同时水绵属丝状藻和刚毛藻属丝状藻也展现出对金属元素累积能力的差异性；丝状藻中的Mn等金属元素主要来自底泥，其次来自河流，丝状藻的锰含量比较综合的反映了河流的锰污染水平和累积情况；松桃河的活体丝状藻对Mn的富集系数达到2.6以上，显示了超强的锰富集和耐受能力，具有广阔的应用前景。     

The Big Seaweed Search: Evaluating a citizen science project for a difficult to identify group of organisms

1. The Big Seaweed Search invites people to survey UK seashores for 14 conspicuous seaweeds. The science investigates: (i) impact of sea temperature rise; (ii) spread of non-native species; and (iii) impact of ocean acidification. Survey data submitted between June 2016 and May 2020 were analysed to evaluate and explore project directions in relation to citizen science project development.
2. Of the 378 surveys submitted, 1,414 people participated, contributing 1,531 person hours. Surveys were undertaken around the UK, with the highest proportion (46.7%) in the south west and the lowest (3.7%) in the north east.
3. After data verification, 1,007 (54%) records were accepted. Fucus serratus had the highest number of entries correctly identified (66%) and Undaria pinnatifida the lowest (5%), inferring that at least some seaweeds can be difficult to identify, although the overall misidentification rate was relatively low (c. 15%).
4. Apart from Alaria esculenta, U. pinnatifida and Saccharina latissima, the large brown seaweeds were abundant on at least some shores. Non-natives Sargassum muticum and Asparagopsis armata, were band-forming but in low numbers. Coralline algae, whilst band-forming on some shores, were most commonly patchy or sparse in abundance. Revisits, i.e. repeat surveys, at the same site with an interval of at least 1 year, are relatively low, with 18 sites revisited once and three sites revisited twice. Currently, data are insufficient to determine whether any changes in abundance could be detected.
5. This study highlights areas where project developments can enhance data quality and quantity, e.g. better identification resources, training programmes for dedicated volunteers, and an annual focus week of activities. The project framed around climate change impacts, aims to raise awareness of the ecological importance of, and threats faced by, this understudied habitat and introduce conservation concepts including the need to protect common species showing signs of decline.