罗非鱼对盐碱池塘围隔浮游生物群落的影响

本文报道了单养尼罗罗非鱼 (Orecohromisniloticus)对施肥处理下盐碱池塘围隔生态系统浮游生物群落的影响。结果表明 ,罗非鱼的放养使浮游植物丰度、叶绿素a含量和初级生产力增大 ,浮游植物小型化 ,生物量以小型硅藻和绿藻占优势 ,裸藻占有相当比重 ;浮游动物生物量也增大 ,桡足类占优势 ,枝角类小型化 ,原生动物密度增大。施肥特别是施有机肥能显著地提高浮游植物生物量 ,使透明度降低 ,但施无机肥对初级生产力和浮游动物生物量影响不大。施有机肥围隔浮游植物和浮游动物密度、浮游动物生物量和浮游生物多样性指数高于其他有鱼围隔 ,罗非鱼的生长最好。文后讨论了罗非鱼滤食和施肥对浮游生物群落结构的影响 ,并与鲢鱼的实验结果 (赵文 ,1999)进行了比较     

罗非鱼对盐碱池塘围隔浮生物群落的影响

本文报道了单养尼罗罗非鱼（Ｏｒｅｃｏｈｒｏｍｉｓ ｎｉｌｏｔｉｃｕｓ）对施肥处理下盐碱池塘围隔生态系统浮游生物群落的影响。结果表明,罗非鱼的放养使浮游植物丰度、叶绿素ａ含量和初级生产力增大,浮游植物小型化,生物量以小型硅藻和绿藻占优势,裸藻占有相当比重;浮游动物生物量也增大,桡足类占优势,枝角类小型化,原生动物密度增大。施肥特别是施有机肥能显著提高浮游植物生物量,使透明度降低,但施无机肥对初级生产     

盐碱池塘围隔生态系统的悬浮物结构及有机碳库储量

1 998年 4～ 7月对高青盐碱池塘单养鲢和罗非鱼围隔生态系统颗粒悬浮物构成和各有机碳库储量及动态进行了研究。结果表明 ,浮游生物的干重 (PZ)占总颗粒悬浮物干物质 (TS)的 4.2 6%～ 2 5 .97% ,平均 1 2 %。各围隔浮游植物干重(DWP)平均值变化范围为 0 .1 6～ 0 .70 mg/L,有鱼围隔均比无鱼围隔的大。浮游动物干重 (DWZ)平均值变化范围为0 .3 2～ 2 .81 mg/L,养鲢围隔中最小 ,小于无鱼对照围隔 ,养罗非鱼围隔明显高于养鲢围隔。颗粒悬浮物的灰分含量平均值为 42 .3 8%。溶解有机碳 (DOC)、颗粒有机碳 (POC)库储量平均值分别为 5 .40± 1 .61 mg C/L和 1 .96± 0 .96mg/L。各处理围隔间颗粒有机物的 C/N比的平均值比较接近 ,总平均值为 6.97± 0 .2 4。 TOC、DOC和 POC比例为 1∶ 0 .73∶0 .2 7。浮游生物碳和腐质颗粒碳占 POC的比例的平均值分别为 3 4.65 %和 65 .3 5 %。腐质颗粒碳、浮游动物碳与浮游植物碳的比例为 9.2 9∶ 3 .71∶ 1。浮游生物碳中浮游动物碳占 78.8% ,浮游植物碳占 2 1 .2 %。浮游动物碳比浮游植物碳高 ,这可能是内陆盐水的通性。盐碱池塘围隔生态系统颗粒有机碳 (POC,mg C/L)与浮游植物叶绿素 a(Chla,μg/L)和悬浮颗粒有机物 (SO,mg/L)之间存在显著的正相关关系 ,其回归方程分别为     

放养鲢鱼(Hypophthalmichys molitrix C et V)对水库围隔浮游生物群落的影响

本文研究在水库围隔实验生态系统中鲢鱼对浮游生物群落的影响。结果表明,放养鲢鱼后,浮游动物生物量、浮游植物生物量、叶绿素a和浮游植物毛产量分别下降了58.7％、63.6％、52.5％和65.0％;透明度、浮游植物群落多样性指数分别提高了18.2％、32.5％;铜绿微囊藻数量减少了90.6％“水华”得到明显抑制。但小型绿藻(<20μm)数量未出现显著变化,因而其在藻类生物量中所占比例反而提高了82.3％。围隔内可被鲢鱼滤食的大型藻类(硅藻、甲藻、隐藻和绿藻(>20μm))占藻类生物量的85.8％,因此鲢鱼的存在能明显限制浮游植物的生物量。此外,放养鲢鱼还显著降低了水体中的COD,TP,DO和pH值,这表明鲢鱼对水质有净化作用。     

盐碱池塘围隔生态系统浮游原生动物种群增长和生产量

1998年 5～ 9月用原位测定法研究了盐碱池塘无鱼和单养鲢围隔生态系统浮游原生动物的种群增长和生产量。结果表明 ,原生动物主要优势种团焰毛虫、瓜形膜袋虫、旋回侠盗虫、绿色前管虫和拟急游虫的世代时间分别为 6 93～ 2 3 10、 6 30～ 18 73、 9 90、 9 90～ 14 75和 7 6 2hr,其种群增长率分别为 0 0 30～ 0 10 0、0 0 37～ 0 110、 0 0 70、 0 0 47～ 0 0 70和 0 0 91/hr。 5～ 8月份无鱼和有鱼围隔原位试验瓶中原生动物累积日均产量分别为 10 70 2 5和 944 2 5mg/m3 ·d ,而相同时间两围隔中原生动物按月计算的日均生产量分别为 1 79和9 72mg/m3 ·d ,日P/B系数分别为 2 5 0和 2 0 3。无鱼围隔原生动物生物量和生产量均比有鱼围隔的低。     

冻融作用下土壤物理和微生物性状变化与氧化亚氮排放的关系

在中、高纬度及高海拔地区,土壤冻融交替现象普遍存在.冻融作用影响土壤的物理和微生物性状,影响土壤的氮素转化过程和强度,导致土壤温室气体氧化亚氮排放增多,使冻融区土壤成为氧化亚氮的重要排放源.冻融作用改变了土壤水分特征和土壤团聚体的稳定性;冻融作用使土壤微生物量、微生物的组成和结构发生改变,导致微生物标识物氨基糖种类和数量改变.本文概述了上述变化与氧化亚氮排放的关系,简要提出了冻融作用下土壤氧化亚氮产生、排放的理论问题及其研究去向.     

罗非鱼对微型生态系统浮游生物群落和初级生产力的影响

本文报道罗非鱼不同放养密度对淡水微型生态系统结构与功能影响的部分研究结果。罗非鱼的捕食使微型生态系统中浮游动物密度下降,引起浮游植物密度、初级生产力和P/R系数的增长,同时使水柱透明度降低而pH值增高,以致于实验后期微型生态系统具有典型的富营养化水体的特征。就罗非鱼放养密度不同的微型生态系统而言,虽然其浮游生物密度和P/R系数存在显著的组(或部分组)间差异,但不同密度组的初级生产力水平和最终的理化状况相差不大,并且罗非鱼的收获量甚为接近。因此,实验条件下微型生态系统的群落结构和代谢的变化,按照营养级联假说不能很好地予以解释,表明微型生态系统是由捕食(下行影响)和理化因素(上行影响)共同调节或控制的。根据微型生态系统的实验结果推断,放养较大密度的罗非鱼,将会加速营养物负荷较高的天然水域富营养化的进程。     

对虾养殖围隔生态系浮游生物群落有机碳的代谢

浮游生物是虾池养殖生态系统生物群落的重要组分 ,在系统的物质循环和能量流动中发挥着重要作用。开展对虾养殖水体浮游生物群落有机碳代谢的研究 ,对阐明虾池养殖生态系统的结构与功能以及指导水质管理均有重要意义。本采用原位实验生态学方法 ,用中尺度实验围隔开展了研究。1　材料与方法1 1　实验围隔及管理实验围隔为 5ｍ× 5ｍ的陆基围隔。以高密度两面涂塑的聚乙烯编织布做围隔幔 ,围隔幔下部埋入池塘底泥 0 5ｍ ,并以木桩和青竹为支架架设于池塘中 (围隔内水深 1 0ｍ )。为了模拟池塘水体的自然混合状况 ,在围隔中间架设了一台 90Ｗ…     

盐度、碱度对浮游生物和水化因子的影响

于 1998年 7～ 8月间在山东省高青县赵店乡大芦湖养殖场选取一口盐碱池塘的池水为实验用水 ,用粗盐和碳酸氢钠调节盐度和碱度 ,以研究盐碱池塘在盐度和碱度升高的情况下其化学、生物因子的变化趋势 .结果表明 ,盐碱池塘中重碳酸盐碱度的升高会在短时间内降低水体 pH值、钙离子浓度和COD ;但碱度为 6.64± 0 .40mmol·L-1～ 13 .47± 0 .3 1mmol·L-1对浮游生物不会产生显著的不良影响 .盐度为 2 .10± 0 .2 2 g·L-1～11.2 9± 0 .99g·L-1会引起浮游生物生物量的降低 ,并减少浮游生物的种类 ,降低其多样性指数 ,影响浮游生物群落结构组成     

Comparison of macroinvertebrate community structure and driving environmental factors in natural and wastewater treatment ponds

Eutrophication still continues to be an issue of major concern for the protection of water quality, and accordingly, the European Union Water Framework Directive has set a minimum target for all waters where “good status” is defined as a slight departure from the biological community which would be expected in conditions of minimal anthropogenic impact. The use of constructed ponds for wastewater treatment aimed at achieving this target has shown to be an effective alternative to conventional systems in the farm landscape. Their applicability in these areas is of great interest since these ponds have the added potential to combine their wastewater treatment properties with that of biodiversity enhancement. This article focuses on exploring the community structure of both natural and constructed ponds used for wastewater treatment and the driving environmental factors. A total of 15 constructed and 5 natural ponds were sampled for aquatic macroinvertebrates and hydrochemistry in spring and summer 2006. Results showed that the most important factors responsible for the differences in the community structure between these two types of ponds were pH, vegetation structure and pollution levels. These gradients helped to structure a large proportion of the communities with some taxa being associated with the constructed ponds. These results highlight the potential contribution of constructed ponds used for wastewater treatment to the landscape biodiversity. The present findings also open the possibility for a more integrated management of water quality and biodiversity enhancement in farmland areas. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users. Guest editors: B. Oertli, R. Cereghino, A. Hull & R. Miracle Pond Conservation: From Science to Practice. 3rd Conference of the European Pond Conservation Network, Valencia, Spain, 14–16 May 2008     

Zooplankton community structure and environmental conditions in a set of interconnected ponds

We studied the zooplankton community structure in a set of 33 interconnected shallow ponds that are restricted to a relatively small area (`De Maten', Genk, Belgium, 200 ha). As the ponds share the same water source, geology and history, and as the ponds are interconnected (reducing chance effects of dispersal with colonisation), differences in zooplankton community structure can be attributed to local biotic and abiotic interactions. We studied zooplankton community, biotic (phytoplankton, macrophyte cover, fish densities, macroinvertebrate densities), abiotic (turbidity, nutrient concentrations, pH, conductivity, iron concentration) and morphometric (depth, area, perimeter) characteristics of the different ponds. Our results indicate that the ponds differ substantially in their zooplankton community structure, and that these differences are strongly related to differences in trophic structure and biotic interactions, in concordance with the theory of alternative equilibria. Ponds in the clear-water state are characterised by large Daphnia species and species associated with the littoral zone, low chlorophyll-a concentrations, low fish densities and high macroinvertebrate densities. Ponds in the turbid-water state are characterised by high abundances of rotifers, cyclopoid copepods and the opposite environmental conditions. Some ponds show an intermediate pattern, with a dominance of small Daphnia species. Our results show that interconnected ponds may differ strongly in zooplankton community composition, and that these differences are related to differences in predation intensity (top-down) and habitat diversity (macrophyte cover).     

The plankton community of Lake Matano: factors regulating plankton composition and relative abundance in an ancient,tropical lake of Indonesia

Recent evidence reveals that food webs within the Malili Lakes, Sulawesi, Indonesia, support community assemblages that are made up primarily of endemic species. It has been suggested that many of the species radiations, as well as the paucity of cosmopolitan species in the lakes, are related to resource limitation. In order to substantiate the possibility that resource limitation is playing such an important role, a study of the phytoplankton and zooplankton communities of Lake Matano was implemented between 2000 and 2004. We determined species diversity, relative abundances, size ranges, and total biomass for the phytoplankton and zooplankton, including the distribution of ovigerous individuals throughout the epilimnion of Lake Matano in three field seasons. The phytoplankton community exhibited very low biomass (<15 μg l^?1) and species richness was depressed. The zooplankton assemblage was also limited in biomass (2.5 mg l^?1) and consisted only of three taxa including the endemic calanoid Eodiaptomus wolterecki var. matanensis, the endemic cyclopoid, Tropocyclops matanensis and the rotifer Horaella brehmi. Zooplankton were very small (<600 μm body length), and spatial habitat partitioning was observed, with Tropocylops being confined to below 80 m, while rotifer and calanoid species were consistently observed above 80 m. Less than 0.1% of the calanoid copepods in each year were egg-bearing, suggesting very low population turnover rates. It was concluded that chemical factors as opposed to physical or biological processes were regulating the observed very low standing crops of phytoplankton which in turn supports a very minimal zooplankton community restricted in both species composition and abundance. As chemical factors are a function of the catchment basin of Lake Matano, it is predicted that resource limitation has long played an important role in shaping the unique endemic assemblages currently observed in the food web of the lake.     

Interactive effects of fertilization and disturbance on community structure and resource availability in an old-field plant community

Summary The interactive effects of fertilization and disturbance on plant community structure and resource availability were studied by supplying four levels of nitrogen and applying four intensities of tilling to a 30 year old field in a factorial design for 2 year. Live above-ground biomass, root biomass, and litter generally increased with nitrogen supply and decreased with disturbance. Species composition varied significantly, with annuals increasing with both nitrogen and disturbance, but with perennials unaffected by nitrogen and decreased by disturbance. Species diversity decreased with disturbance, but decreased with nitrogen only in undisturbed vegetation. Root: shoot ratios decreased with added nitrogen, leaf allocation decreased with disturbance, and flowering allocation increased. Surprisingly, stem allocation was unaffected by disturbance. This result reflected a shift from vertical stems to horizontal stems as disturbance increased. Resource measurements suggested that the vegetation responded to interactions between the treatments as well as to direct treatment effects. Variation in light penetration was reduced by fertilization in undisturbed vegetation but not in tilled plots; variability was not directly affected by disturbance. The availability of nitrogen, the limiting soil nutrient, increased with fertilization but was not significantly affected by disturbance. In contrast, the ratio of ammonium to nitrate was significantly reduced by disturbance but unaffected by supply rates, suggesting that nitrogen may have had different effects under different disturbance regimes, even though its total availability was constant. While many community responses to fertilization and disturbance conformed to those reported earlier, resource and allocation measurements indicated that their interactions are not always predictable from their separate effects.     

The role of zooplankton in the ecological succession of plankton and benthic algae across a salinity gradient in the Shark Bay solar salt ponds

The relatively low biodiversity and simple hydrodynamics make solar salt ponds ideal sites for ecological studies. We have studied the ecological gradient of the primary ponds at the Shark Bay Resources solar salt ponds, Western Australia, using a coupled hydrodynamic ecological numerical model, DYRESM–CAEDYM. Seven ponds representative of the primary system were simulated with salinity ranging from 45 to 155 ppt. Five groups of organisms were simulated: three phytoplankton, one microbial mat plankton, and one zooplankton as well as dissolved inorganic and particulate organic nitrogen, phosphorus, and carbon. By extracting the various carbon fluxes from the model, we determined the role that the introduced zooplankton, Artemia sp., plays in grazing the particulate organic carbon (POC) from the water column in the high salinity ponds. We also examined the nutrient fluxes and stoichiometric ratios of the various organic components for each pond to establish the extent to which observed patterns in nutrient dynamics are mediated by the presence of Artemia sp. Model results indicated that Artemia sp. grazing was responsible for reduced water column POC in the higher salinity ponds. This resulted in an increase in photosynthetic available radiation (PAR) reaching the pond floor and consequent increase in microbial mat biomass, thus demonstrating the dual benefits of Artemia sp. to salt production in improved quality and quantity. In contrast, this study found no direct link between Artemia sp. and observed changes in planktonic algal species composition or nutrient limitation across the salinity gradient of the ponds. Guest Editors: J. John & B. Timms Salt Lake Research: Biodiversity and Conservation—Selected Papers from the 9th Conference of the International Society for Salt Lake Research     

Exploring spatio-temporal patterns of plankton diversity and community structure as correlates of water quality in a tropical stream

Ecology of plankton in the downstream reaches of Kaduna River, Zungeru, Niger state, Nigeria was investigated between April and August 2015. Plankton and surface water samples were collected monthly from three stations for analysis of plankton diversity and physico-chemical parameters respectively. Station 1 is relatively unperturbed station located at the outskirts of Zungeru town, station 2 with moderate human activity located in Zungeru town while station 3 with minimal level of anthropogenic activities was located in Wushishi town about 7 km from station 2. The result revealed that the minimum and maximum values for pH water temperature, air temperature, conductivity, dissolved oxygen (DO) biochemical oxygen demand (BOD), phosphate, Nitrate, and secchi disc transparency were 5.38–6.79, 25–31 °C, 26–31 °C, 32–72 μs/cm, 3.50–8.20 mg/l, 1.00–5.00 mg/l, 0.06–1.13 mg/l 0.44–1.31 mg/l, 39.140 cm respectively. A total of 26 species of zooplankton and 24 species of phytoplankton were encountered in the study. The highest number of plankton (20 taxa) was recorded at station 2 while station 1 with 18 taxa and station 3 with 13 representative taxa. For zooplankton, the highest number of taxa was recorded at station 1 (20 taxa), followed by station 3 (14 taxa) and 10 taxa in station 2 were identified. Copepoda of the order cyclopidae dominated all the three stations while Bacillariophyta dominated the three stations for phytoplankton diversity. Canonical correspondence analysis (CCA) ordination was used to determine phytoplankton and zooplankton abundance in relation to the physico-chemical parameters. Nitrate, phosphate and dissolved oxygen had over riding influence on the distribution of the plankton in the water body which indicate that the river is still very productive in terms of providing starter food organisms for higher aquatic life. However, care should be taken to protect the river from further deterioration due to various degrees of human activities.     

Effects of elevated CO2 and phosphorus addition on productivity and community composition of intact monoliths from calcareous grassland

We investigated the effects of elevated CO₂ (600 μl l⁻¹ vs 350 μl l⁻¹) and phosphorus supply (1 g P m⁻² year⁻¹ vs unfertilized) on intact monoliths from species-rich calcareous grassland in a greenhouse. Aboveground community dry mass remained almost unaffected by elevated CO₂ in the first year (+6%, n.s.), but was significantly stimulated by CO₂ enrichment in year two (+26%, P<0.01). Among functional groups, only graminoids contributed significantly to this increase. The effect of phosphorus alone on community biomass was small in both years and marginally significant only when analyzed with MANOVA (+6% in year one, +9% in year two, 0.1 ≥P > 0.05). Belowground biomass and stubble after two seasons were not different in elevated CO₂ and when P was added. The small initial increase in aboveground community biomass under elevated CO₂ is explained by the fact that some species, in particular Carex flacca, responded very positively right from the beginning, while others, especially the dominant Bromus erectus, responded negatively to CO₂ enrichment. Shifts in community composition towards more responsive species explain the much larger CO₂ response in the second year. These shifts, i.e., a decline in xerophytic elements (B. erectus) and an increase in mesophytic grasses and legumes occurred independently of treatments in all monoliths but were accelerated significantly by elevated CO₂. The difference in average biomass production at elevated compared to ambient CO₂ was higher when P was supplied (at the community level the CO₂ response was enhanced from 20% to 33% when P was added, in graminoids from 17% to 27%, in legumes from 4% to 60%, and in C. flacca from 120% to 298% by year two). Based on observations in this and similar studies, we suggest that interactions between CO₂ concentration, species presence, and nutrient availability will govern community responses to elevated CO₂. Received: 12 July 1997 / Accepted: 28 March 1998     

Temporal variations and pond age effect on plankton communities in semi-intensive freshwater marron (Cherax cainii,Austin and Ryan, 2002) earthen aquaculture ponds in Western Australia

The abundance and diversity of the plankton community represents the health of the aquatic ecosystem, and plays an important role in the growth of cultured animals under aquaculture conditions. The temporal variations of plankton abundance, taxonomic composition, diversity, evenness and species richness were studied in three old and three new semi-intensive marron (Cherax cainii, Austin and Ryan, 2002) ponds. Water parameters such as temperature, dissolved oxygen, pH, turbidity, TAN, nitrite, nitrate and reactive phosphate were recorded, and plankton samples were collected every two months, for one year of juvenile production cycle. A total of twenty-six phytoplankton and seven zooplankton genera were recorded. Chlorophyceae was the dominant class of phytoplankton throughout the year, followed by Trebouxiophyceae. Rotifera comprised 49.8% of the total zooplankton community (individuals L^?1), the largest proportion of any group. Temporal variations impacted the plankton abundance and community structure, and plankton abundance were more abundant during summer. The pond age did not influence the phytoplankton abundance, whereas zooplankton abundance was higher in older ponds.