Geographical variations in the trophic structure of the plankton community along a eutrophic–mesotrophic–oligotrophic transect

The geographical variations in trophic structure of the plankton community, as defined by total and relative carbon biomass of phytoplankton (PP), bacteria (BA), heterotrophic nanoflagellates (HNF), microzooplankton (MZ), and herbivorous (HNZ) and carnivorous net-zooplankton (CNZ), were investigated along an inshore–offshore transect from the innermost part of Osaka Bay to the Pacific Ocean off Kii Channel, Japan, in June 1991. Based on physico-chemical properties of the water and topographical features, the transect was divided into three trophic areas, i.e. eutrophic, mesotrophic and oligotrophic ones. The average carbon biomass of the total plankton community was highest (438 mg m⁻³) in the inshore eutrophic area, and declined steeply offshore (141 and 26.6 mg m⁻³ in the mesotrophic and oligotrophic areas, respectively). In the offshore oligotrophic area, the relative biomass of BA to PP and the relative biomass of small heterotrophs (i.e. BA, HNF and MZ) to the total heterotrophs were higher than in the other areas, indicating that the microbial food chain predominated. In the mesotrophic area, the biomass of HNZ (primarily copepods) was conspicuously high, even higher than that of PP, suggesting that the traditional grazing food chain prevailed. Because of this short food chain, a productive fishing ground is formed there. In the eutrophic area, the biomass of HNZ was much smaller relative to the enormous biomass of PP, indicating that a considerable amount of primary production was not utilized directly by the metazoan zooplankton. However, the relative contribution of the small heterotrophs to the total heterotrophs' biomass was higher in this area, as in the oligotrophic area.     

晋南盐水水域生物资源调查：三,盐池

报道了１９８２－１９９０年间对盐池生物资源所进行的５次调查的结果,该湖水型一般为ＮａＭｇＳＯ４Ｃｌ型或ＭｇＮａＣｌＳＯ４型,盐度４．９５－３１１．５ｇ／Ｌ,ｐＨ值为７．５－１０．６,碱度２．５－２２．４ｍｍｏｌ／Ｌ。共见到５３种浮游植物,４７种浮游动物、种底栖动物和１种鱼类。浮游生物优势种类主要有盐藻,隐头舟形藻,舟形藻,孟氏小环藻,小颤藻,普通小球藻,湖生卵囊藻,卤虫,褶皱臂尾轮早,蒙古裸腹Ｓｈ     

光照条件下生物絮凝养殖调控的措施

运用实验生态学的方法,以阳光工厂化生物絮凝养殖前期水为实验材料,分别探究去细菌捕食者(原生动物等,AC组)、带虾序批添加葡萄糖(GS组)和一次性添加葡萄糖(G组)对水中微食物环的细菌及浮游生物的影响。结果表明,GS组在120 h的轮虫生物量、浮游植物生物量和叶绿素a含量都显著高于对照组(P0. 05)和而G组的轮虫生物量、浮游植物生物量在整个实验过程中与对照组无显著性差异(P 0. 05),因此序批式添加葡萄糖的上行效应比一次性添加更加明显,并且添加大型捕食者的GS组的下行效应不明显。实验组和对照组细菌总数都大于5×10~5个/mL,AC组的细菌总数峰值最高[(13. 10±3. 79)×10~5个/mL],去细菌捕食者后降低了对细菌的捕食压力从而促进了细菌生长。AC组的溶解性有机碳浓度和溶解性总氮浓度一直高于其他组,GS组、G组和对照组的溶解性有机碳、溶解性总氮和磷酸盐浓度的变化趋势基本一致,杀死细菌捕食者释放了大量溶解性有机物,添加适量葡萄糖、投放虾对养殖水质无明显影响。研究结果为阳光型生物絮凝养殖在生产应用上的调控手段提供基础依据。     

循环养殖系统中多级生物处理对水质的调控作用

研究了根据不同生物的功能特性及其间的协同作用,建立的由芦苇湿地、沉水植被群落、人工基质固定化微生物膜、软体底栖动物和滤食性鱼类组成的自净型多级生物修复系统,对养殖塘环境改善情况。结果显示:与实施修复前的系统相比,营养盐NO2-N、NO3-N和PO4-P的去除率分别达87.46%、62.99%和75.74%;浮游动、植物的生物量分别减少92.83%和15.90%。养殖塘排水营养盐NO2-N、NO3-N和PO4-P的去除率分别为27%～96%(年均87%)、37%～84%(年均84%)和30%～17%(年均9%),CODMn的去除率为1%～17%(年均9%)。经系统多级处理后水体透明度分别提高了75%和17%,最高值达52 cm。浮游植物生物量平均减少63.93%,尤其是蓝藻,平均减少68.17%。浮游植物群落结构转好,硅藻大量繁殖,成为优势种。浮游动物群落结构也由小型原生动物占优向大型枝角类、轮虫转变。受控于滤食性鱼类,浮游动物生物量维持在较低水平。     

North–south contrasts in decadal scale variations in lower trophic-level ecosystems in the Japan Sea

Regional comparisons of interannual variations in springtime lower trophic-level ecosystems were made for northern subarctic regions, and for southern Tsushima Current regions of the Japan Sea, based on archival hydrographic and biological data sets collected from the mid-1960s to the early 1990s. Variations related to the Pacific Decadal Oscillation were detected for plankton biomass in both northern and southern regions, although there were regional differences with respect to mechanisms and timing. Springtime stratification increased after the late 1970s in the north, roughly coinciding with the northern Pacific regime shift in 1976/77. Stratification also increased due to warming in the south in the early 1980s, several years after the 1976/77 regime shift. Responding to the increase in stratification, springtime biomass of phytoplankton and zooplankton increased in the north and decreased in the south. Principal component analysis revealed that hydrographic conditions during spring, rather than winter, determined springtime phytoplankton biomass. In northern regions, spring phytoplankton production may be enhanced by increased light availability, due to mixed layer stabilization. In the south, where background nutrient concentration within the water column was low, increases in stratification were likely to limit nutrient supply to the surface layer, resulting in decreases in phytoplankton production. A positive relationship between phytoplankton and zooplankton biomass suggested bottom-up control of secondary production in northern regions. The nature of the links between phytoplankton and zooplankton production was not clear in southern regions, where hydrographic conditions during winter seemed to be responsible for variations in springtime secondary production.     

Dynamics of dissolved and particulate polyunsaturated aldehydes in mesocosms inoculated with different densities of the diatom Skeletonema marinoi

A survey of the production of polyunsaturated aldehydes (PUA) of manipulated plankton communities is presented here. PUA are phytoplankton-derived metabolites that are proposed to play an important role in chemically mediated plankton interactions. Blooms of different intensities of the diatom Skeletonema marinoi were generated in eight mesocosms filled with water from the surrounding fjord by adding different amounts of a starting culture and nutrients. This set-up allowed us to follow PUA production of the plankton community over the entire induced bloom development, and to compare it with the natural levels of PUA. We found that S. marinoi is a major source for the particulate PUA 2,4-heptadienal and 2,4-octadienal (defined as PUA released upon wounding of the diatom cells) during the entire bloom development. Just before, and during, the decline of the induced diatom blooms, these PUA were also detected in up to 1 nM concentrations dissolved in the water. In addition, we detected high levels of the PUA 2,4-decadienal that was not produced by the diatom S. marinoi. Particulate decadienal correlated well with the cell counts of the prymnesiophyte Phaeocystis sp. that also developed in the fertilized mesocosms. Particulate decadienal levels were often even higher than those of diatom-derived PUA, indicating that PUA sources other than diatoms should be considered when it comes to the evaluation of the impact of these metabolites.     

大连大孤山海区水下爆破对海洋环境及浮游生物的影响

为了解大连湾大孤山海区水下爆破活动对其所在海区水质及浮游生物的影响,于2007年的9—12月对爆破后2 h和1 000 m范围内的爆破区域进行了监测,内容包括透明度、盐度、溶氧、pH、悬浮物、油、氨态氮、硝酸氮、亚硝酸氮、活性磷10项水质指标和叶绿素a、浮游植物生物量、浮游动物生物量3个生物指标。结果表明：爆破对海区透明度和悬浮物的影响显著,对其它指标影响不显著。整体上,本次爆破不会对该海区水质及浮游生物量产生明显的影响。     

轮虫培育池浮游生物种类组成及生物量的研究

所测９个淡水轮虫池和６个混盐水轮虫池的浮游植物生物量,在轮虫发生高峰前期平均分别为１１７．８ｍｇ／Ｌ和１５６．５ｍｇ／Ｌ;在轮虫高峰期平均为３９．０ｍｇ／Ｌ和８２．３ｍｇ／Ｌ,即高峰期浮游植物生物量只为前期的１／３～１／２。在种类组成上,前期均以小球藻、蓝隐藻、小环藻等小型种类为主,高峰期则以衣藻、扁藻等鞭毛藻类及角毛藻、螺旋藻、颤藻等丝状群体占优势。淡水池和混盐水池浮游动物生物量平均分别为６６．     

富地营子水库秋季浮游生物及鱼产潜力

富地营子水库秋季浮生物共计92个种别，其中浮游植物48个种属，浮游动物44个种属，浮游植物数量199．80x104ind．／L，生物量1．7746mg／L,浮游动物数量6052．25ind．／L，生物量8．S693ms／L，全库总鱼产潜力451902．02ks，总放养量2344512尾.     

咸淡水集约化草鱼池塘饲料投喂量与水质及浮游生物的关系

对广州市诚一水产养殖有限公司3个咸淡水草鱼池塘的浮游生物、水质和饲料投喂量进行了为期1 a的调查,并利用SPSS和Canoco 5.0对数据进行相关性、排序和多元回归分析.结果显示:池塘饲料投喂量与水体总氮浓度呈显著正相关关系,r=0.614(P<0.05);与水温、pH、透明度、溶氧、亚硝酸盐、氨氮、总磷和盐度等水质...