云龙湖水库浮游生物调查及鲢、鳙鱼产潜力估算

2005年6月和10月分2次对云龙湖水库进行了4个样点的浮游生物调查。共采集到的浮游植物分属6门、28属,平均密度为4.925×106个/L,平均生物量为1.620mg/L;浮游动物29属,包括原生动物11属、轮虫10属、枝角类4属、桡足类4属,平均密度为30353.75个/L,平均生物量2.590mg/L。由此估算鲢、鳙鱼产潜力为83639kg;其中,鲢生产潜力为15603kg,鳙生产潜力为68036kg。按起水规格鲢750g、鳙1250g计算,鲢、鳙鱼种理论放养比例约为4∶11。     

主养凡纳滨对虾池塘水体理化因子及浮游生物变化特征

选取3个主养凡纳滨对虾的鱼虾混养池塘,在养殖季节(5—10月)每月对池塘水体理化性质和浮游生物进行监测。通过定期监测,研究了该类型池塘水体理化性质和浮游生物的时空变化特点。结果表明:在整个养殖过程中,p H随养殖时间延长略有上升,但是变化较小;化学需氧量和亚硝态氮呈上升趋势;总氮、总磷、锌离子、总碱度浓度呈先下降后上升趋势;氨氮浓度在养殖前期最高,随养殖时间延长逐渐下降,养殖后期趋于稳定;硝态氮浓度呈波浪形变化,但整个养殖过程浓度都比较低;活性磷浓度呈下降趋势;铜离子和悬浮物浓度呈先下降后上升再下降的趋势;盐度总体趋势平稳;总硬度呈先上升后下降趋势。养殖过程中共检测到7门38种藻类,养殖池塘浮游植物主要以绿藻门和蓝藻门为主;共检测到5类18种浮游动物,浮游动物组成主要以轮虫类和枝角类为主。综合浮游植物和浮游动物的调查结果,由Shannon-Wiener指数分级评分标准可知养殖前期的水质较差,浮游生物丰富度较低。     

鲢、鳙非经典生物操纵作用的研究进展与应用现状

鲢、鳙作为内陆水域主要的滤食性经济鱼类,通过对浮游生物的摄食行为抑制蓝藻水华的发生,这种干预现象在水域生态学领域称为非经典生物操纵。综述了鲢、鳙非经典生物操纵作用的研究与应用进展。目前关于鲢、鳙非经典生物操纵作用存在２种不同的观点。一种观点认为鲢、鳙大量滤食浮游生物,在控制蓝藻水华的同时还可将水中有机物转化为鱼产品移出,能够有效控制水体富营养化;另一种观点认为,放养鲢、鳙实际加快了水体营养盐的周转速率,在抑制蓝藻水华的同时加快了水体的富营养化进程。针对这２种不同观点开展的实验与调查表明,鲢、鳙放养对于抑制藻类水华的爆发作用明确,但同时导致浮游动植物小型化,浮游生物的数量会由于水体营养盐周转速率的加快而出现大幅波动。综合各方观点作者认为,鲢、鳙对于水体蓝藻水华形成的预防和抑制作用证据较为明确,但对于一定时期内水体营养盐变化的影响存在较大的不确定性,与水文条件、鲢鳙存量、集水区状况等有密切的关联。     

河口区斑节对虾淡化养殖塘浮游生物状况

初步研究了 1998年河口区斑节对虾淡化养殖塘生态系中的浮游生物状况。各塘浮游植物生物量变幅较大 ,平均含量为 36 .33± 2 8.4 0mg/L ;浮游植物总密度均值为 3.0 5± 2 .18× 10 8cells/L ,水体已呈富营养化状态。浮游植物的生物量及种类数均以蓝藻占优势 ,其次是绿藻和硅藻 ,这与我国传统家鱼高产池塘的浮游植物群落结构显著不同。各塘浮游动物丰度与组成变化较大 ,不如浮游植物稳定。浮游植物与浮游动物生物量之比平均为 0 .90 3:1,斑节对虾塘尚有进一步开发的潜力     

上海黄浦江倪家浜口浮游生物调查与水质评价

上海市黄浦江倪家浜口是中国2010年上海世博园后滩水系和东方体育中心人工湖的重要取水口,其水体状况直接影响世博园后滩湿地、世博园生活与日常杂用水,以及体育中心人工湖水体景观。为评估该地区水体健康状况,为后滩水系和人工湖取水工程建设与维护管理提供依据,我们根据2007年2月至12月倪家浜口不同潮位调查,分析了该区域浮游生物的种类组成、优势种类、物种多样性等特征参数的变化。调查期间共鉴定出浮游藻类8门45属,主要优势种为小席藻（Phormidium tenue）、四尾栅藻（Scenedesmus quadricauda）、极大螺旋藻（Spirulina maxima）等;浮游动物3门32种,主要优势种为萼花臂尾轮虫（Brachionus calyciflorus）、前节晶囊轮虫（Asplanchna priodonta）、发头裸腹溞（Moina irrasa）等。叶绿素a含量表现出明显的季节变化。多样性分析显示,浮游藻类香农威尔指数为0.88～2.96,浮游动物香农威尔指数为0.92～2.98。数据分析表明,种类数及多样性指数与温度呈正比,倪家浜口处于中度富营养化状态,水质处于中-重污带级,且夏秋季水质优于冬春季,当天高潮时水质优于低潮。     

不同单养和混养海水实验围隔浮游生物的研究

1995年6～10月和1996年6～8月对中国对虾单养及其与台湾红非鲫、菲律宾蛤仔、海湾扇贝或缢蛏的不同混养实验围隔浮游生物的研究结果表明:养殖管理措施和放养种类对围隔浮游生物种类和生物量都会产生一定影响,其中前者往往具主要作用。投饵养殖时围隔浮游植物以20μm以下的种类为主,生物量较低,其中混养台湾红非鲫的围隔叶绿素a(Chl-a)相对较高,混养菲律宾蛤仔的围隔Chl-a较低;在投饵的基础上施肥后甲藻等鞭毛藻类易大量发生成为优势种,浮游植物生物量较单纯投饵时有所升高,但单养和混养对围隔Chl-a的影响不明显。非鲫捕食往往导致大型桡足类在浮游动物生物量中的比例下降,贝类则通过食物竞争同时使桡足类生物量降低和种类小型化,由于非鲫与海产贝类的食物灶存在一定分化,二者混养至少对贝类有利,因此鱼虾贝混养应较鱼虾混养或虾贝混养效果更好。     

Towards a more balanced view of marine ecosystems

Frank et al. (Nature, 477 , 2011, 86) hypothesize that the slow recovery of the Scotian Shelf ecosystem to its structure prior to the early 1990s is a result of the oscillatory, runaway consumption dynamics of the forage fish complex. Their hypothesis is based on the underlying assumptions that this ecosystem's dynamics are governed by top‐down forcing, predator–prey role reversals, and a trophic cascade extending from demersal predatory fish, especially cod, down to the level of nutrients (Science, 308 , 2005, 1621; Nature, 477 , 2011, 86). Greene and Pershing (Science, 315 , 2007, 1084) called into question the underlying assumption of an extended trophic cascade. They argued that while top‐down forcing can be important at higher trophic levels in many Northwest Atlantic Shelf ecosystems, its impacts on zooplankton, phytoplankton, and nutrients are minor or nonexistent. Instead, they argued that lower trophic‐level dynamics in these ecosystems are governed by climate‐associated, bottom‐up forcing. Observations over the past three decades (Greene et al. Ecology, 89 , (Suppl 11), 2008, S24; MERCINA Oceanography, 25 , 2012, 208.) are consistent with predictions from the climate‐forcing hypothesis proposed by Greene and Pershing (Science, 315 , 2007, 1084), while those from the past decade (MERCINA, Oceanography, 25 , 2012, 208) demonstrate that the trophic cascade hypothesis as proposed by Frank et al. (Science, 308 , 2005, 1621) should be rejected. A closer examination of these observations also calls into question the hypothesis of ecosystem recovery in the Northwest Atlantic being governed by the oscillatory, runaway consumption dynamics of the forage fish complex.     

Diatom derived polyunsaturated aldehydes do not structure the planktonic microbial community in a mesocosm study

Several marine and freshwater diatoms produce polyunsaturated aldehydes (PUA) in wound-activated processes. These metabolites are also released by intact diatom cells during algal blooms. Due to their activity in laboratory experiments, PUA are considered as potential mediators of diatom-bacteria interactions. Here, we tested the hypothesis that PUA mediate such processes in a close-to-field mesocosm experiment. Natural plankton communities enriched with Skeletonema marinoi strains that differ in their PUA production, a plankton control, and a plankton control supplemented with PUA at natural and elevated concentrations were observed. We monitored bacterial and viral abundance as well as bacterial community composition and did not observe any influence of PUA on these parameters even at elevated concentrations. We rather detected an alternation of the bacterial diversity over time and differences between the two S. marinoi strains, indicating unique dynamic bacterial communities in these algal blooms. These results suggest that factors other than PUA are of significance for interactions between diatoms and bacteria.