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.     

鄱阳湖国家级自然保护区浮游生物群落结构及空间分布

为评价春季大旱后鄱阳湖国家级自然保护区浮游生物现状,对保护区所辖 8 个子湖及赣江和修河部分河段的浮游生物进行调查和分析。调查共发现浮游植物 53 属 97 种、浮游动物 23 属 42 种（包括原生动物 13 种、轮虫 23 种、枝角类 3 种和桡足类 3 种）,其中大湖池和朱市湖是浮游生物种类数最多的 2 个子湖。各子湖及赣江和修河间浮游生物现存量差异较大,其变化范围分别为260（8.18106）cells/L（浮游植物）、363073173 ind./L（浮游动物）,赣江以西区域的子湖和修河的浮游生物现存量显著高于赣江及其以东区域的子湖。调查水域优势度值（Y）大于 0.02 的浮游生物包括蓝藻 1 种、绿藻 2 种、硅藻 5 种、原生动物 4 种及轮虫 5 种。浮游生物 Shannon-Wiener 多样性指数（H'）和均匀度指数（J）的最大值均分别为 2.41 和 0.96,而其丰富度指数（Dm）值均小于 3。3 种多样性指数综合评价表明,保护区各子湖与修河和赣江水体受污染程度较轻,除蚌湖和梅西湖外,均处于中污状态。       

广东长潭水库浮游生物群落结构特征

长潭水库是广东梅州市重要的备用水源地,属于国家一类水源保护区。2010年7月,通过分析长潭水库浮游生物群落组成、生物量及多样性指数等群落结构特征和水体理化指标,揭示长潭水库富营养化水平。结果显示,长潭水库鉴定出55种浮游植物,隶属于6个门,优势种为绿藻门的栅藻（Scenedesmus sp.）、蓝藻门的微囊藻（Microcystis sp.）和伪鱼腥藻（Pseudanabaena sp.）、隐藻门的隐藻（Cryptophyta sp.）以及硅藻门的小环藻（Cyclotella sp.）和针杆藻（Synedra sp.）;藻类密度范围1.71×10⁶~2.44×10⁸ cells/L;浮游动物共检出44种,包括轮虫、枝角类和桡足类,其中轮虫是主要类群。综合营养状态指数评价结果显示,长潭水库部分水体呈轻度富营养化。典范对应分析结果显示,浮游动物、溶解氧、总氮、总磷和化学需氧量是影响长潭水库浮游植物群落结构的关键环境因子。     

The effects of the flood cycle on the diversity and composition of the phytoplankton community of a seasonally flooded Ramsar wetland in Bangladesh

Freshwater wetlands in Bangladesh are strongly influenced by the monsoons and the annual flood cycle has measurable impacts on the abiotic and biotic components of these ecosystems. The northeastern Haor Basin of Bangladesh is particularly rich in seasonally flooded freshwater wetlands that support a wide diversity of flora and fauna. These wetlands are of great importance to the local economy due to the abundance of rich floodplain fisheries. Little is known about the phytoplankton communities of these wetlands that are known to be linked with zooplankton and fish productivity. We investigated the seasonal variation in the diversity and abundance of phytoplankton assemblages in Tanguar Haor, a Ramsar wetland in northeastern Bangladesh during the period of inundation (June–December). A total of 107 genera of phytoplankton representing five classes were recorded. Blooms of Microcystis dominated the phytoplankton community throughout the study period but were particularly acute during the early part of the high water period. Among the Bacillariophyceae, Melosira was the most dominant, reaching bloom proportions early in the high water period. Factor analysis of physicochemical variables separated the flood cycle into four distinct periods: early high water, mid high water, late high water and low water periods. Phase of the flood cycle, nutrient availability, the physicochemical variables combined with the dominance of Microcystis seemed to be important in controlling the abundance, diversity and dynamics of the phytoplankton genera. The abundance of genera of desmids and some Bacillariophyceae is indicative of the relatively unpolluted conditions of Tanguar Haor.     

Wetland degradation leads to homogenization of the biota at local and landscape scales

1. We examined whether the anthropogenic degradation of wetlands leads to homogenization of the biota at local and/or landscape scales and, if so, what specific factors account for such an effect. We compared 16 isolated wetlands (Michigan, U.S.A.) that varied in surrounding land use: half had developed, and half undeveloped, riparian zones. Samples of macrophytes, epiphytic diatoms, zooplankton, macroinvertebrates and water chemistry were collected along three transects in each wetland. 2. Developed wetlands were more nutrient‐rich with higher Cl concentrations. The plant community at developed sites was dominated by Lemnaceae (duckweed), while undeveloped wetlands were dominated by rooted, floating‐leaved vegetation and sensitive plant species. Undeveloped wetlands contained heterogeneous and species‐rich plant communities, greater species richness of zooplankton and diatoms, and heterogeneous zooplankton distributions as compared to developed sites. 3. A comparison among wetlands showed that diatom and zooplankton assemblages in developed wetlands were nested subsets of richer biota found in less developed wetlands. Conversely, plant communities were more heterogeneously distributed among developed wetlands at the landscape level. This may be attributable to patchy invasions by exotic species, which were a feature of the degraded wetlands within developed landscapes. 4. Our results indicate that several taxonomic groups showed similar, probably inter‐dependent, responses to wetland degradation and habitat homogenization at both the local and landscape scales. This change in community structure from a species‐rich and heterogeneous community dominated by floating‐leaved plants in undeveloped wetlands, to nutrient‐rich wetlands dominated by duckweed may represent a shift to an alternate stable state.     

Aquatic macroinvertebrate community responses to wetland mitigation in the Greater Yellowstone Ecosystem

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Plankton abundance in relation to physicochemical factors in the Bui reservoir of Ghana's Black Volta River

The relationship between physicochemical factors and plankton abundance in the newly created Bui reservoir was studied during 2011 and 2012. The objective was to assess the influence of physicochemical factors on plankton abundance and provide data for monitoring the hydrobiology of the newly created Bui reservoir. Two sampling stations were selected on the Black Volta upstream (Bui) and downstream (Bamboi) of the dam, with samples taken pre‐ and postimpoundment during the study period. Canonical Correspondence Analysis (CCA) was used to trace temporal plankton community changes and to examine the relationships between species composition and physicochemical variables. The relative abundance of some phytoplankton species such as Anabaena sp., Planktothrix sp. and Scenedesmus sp. was directly correlated to nitrates. CCA indicated that physicochemical variables explained 41–64% of zooplankton and 8–12% of phytoplankton variation. Hence, there were correlations between environmental variables and the structure of plankton assemblages. This feature should therefore be used for bio‐monitoring of environmental variables of the river by the Bui Power Authority to ensure protection of the aquatic biota downstream of the Bui dam.     

Habitat Attributes and Waterbird-Use of Four Wetlands in Manas National Park,Assam, India

We studied the relationship between habitat characteristics and the use of wetlands by the waterbirds over 5 years in Manas National Park, Assam. Patterns of temporal and spatial variation in waterbird diversity, abundance and community composition were quantified in relation to eight wetland attributes. There were significant declines in majority of the waterbird species during the course of this study; carnivorous and omnivorous birds being the major sufferers. The waterbird communities exhibited both spatial and temporal shifts in distribution and community composition along with the shifts in their major food resources, and primary productivity of the wetlands did not appear to play a major role in these shifts. Our study also demonstrates that the observed declines in waterbird abundances were associated with declines in zooplankton and macroinvertebrate densities. Temporal changes in wetland size also played some roles in the waterbird decline and community composition.     

Influence of Pulsed Inflows and Nutrient Loading on Zooplankton and Phytoplankton Community Structure and Biomass in Microcosm Experiments Using Estuarine Assemblages

Productivity and community structure of phytoplankton and zooplankton are influenced by hydrologic disturbances in many ways. In a recent modeling study it was suggested that pulsed inflows might enhance zooplankton performance, curb accumulation of phytoplankton accumulated biomass, and promote phytoplankton species diversity. We tested these predictions by performing microcosm experiments on natural plankton assemblages from the Nueces Delta, TX, USA. On three occasions (March, June, and September 2001), experiments of semi-continuous and flow-through design were conducted using natural plankton assemblages. We investigated the effect of two different inflow and nutrient loading regimes on zooplankton biomass, and phytoplankton biomass and diversity, i.e., continuous and pulsed inflows of 3 day frequency. Despite differences in initial community structure on these three occasions, as well as the very different communities that arose between experimental designs, our findings showed that pulsed inflows altered plankton dynamics. In all cases, pulsed inflows resulted in greater zooplankton biomass. In most cases, pulsed inflows resulted in lower phytoplankton biomass and higher diversity. We speculate that greater phytoplankton diversity in the pulsed flow treatments favored selectively feeding zooplankton, whose better performance prevented higher accumulation of phytoplankton biomass.     

灞河城市段浮游生物群落结构时空变化及其与环境因子的关系

为了解灞河城市段浮游生物群落结构及其与环境因子之间的关系,于2016年9月至2017年7月每2个月进行一次采样分析。调查期间共鉴定出浮游植物7门63属,其中绿藻门种类数最多(34.9%),其次为硅藻门(30.2%);浮游动物4类45种,以轮虫(48.9%)和原生动物(24.4%)为主。浮游植物和浮游动物的丰度分别为0.73×10~4—98.5×10~4个/L和20—1084个/L,在时空分布上均呈现下游高于上游的趋势,峰值均出现在夏季。根据水体透明度、溶解氧、总磷、总氮、高锰酸盐指数和重金属等理化指标、浮游生物丰度、Shannon-Wiener多样性指数和Margalef丰富度指数对灞河城市段水质状况进行综合评价,结果显示,所研究流域总体为中污状态,上游景观河道内的水生植物对水体具有一定的修复能力。典范对应分析表明,水温、总氮、pH、溶解氧和汞是浮游植物群落分布的主要影响因子;影响浮游动物群落分布的主要因子为水温、总氮、总磷、叶绿素a和汞。     

湿地中的藻类生态学研究进展

从湿地中藻类的种群结构、藻类在湿地中的功能、湿地中的藻类生产力及其影响因素等方面综述了天然湿地中的藻类生态学研究进展．湿地植物区系主要有附泥藻类、附植藻类、后周丛藻类和浮游植物4种类型,其中常见的是附泥藻类的硅藻、绿藻和蓝藻．藻类最显著的作用是作为湿地食物网中的初级生产者,也作为湿地环境污染的生物指示物．影响藻类生产力的因素有水力学因素、营养、温度、光、大型植物及草食动物和其它动物．未来对藻类的研究应侧重于湿地藻类生物多样性、藻类生物量、生产力、种群组成的环境控制及其相互关系,以及藻类作为水环境及湿地污染程度指标的研究,“基因治藻”也将是未来研究的新方向．     

Can the use of zooplankton dormant stages from natural wetlands contribute to restoration of mined wetlands?

Wetlands are among the most diverse environments on the planet and are strongly threatened by human activities. Their restoration and/or mitigation of human impacts, therefore, relies on information that can aid to the management of impacted wetlands so that they return to a (semi-) natural state. We investigate in this study the relationship between dormant stages of zooplankton and clay removal in areas subjected to mining. We evaluate whether a gradual increase in topsoil addition from donor natural wetlands to the sediment of mined wetlands influenced the zooplankton community. Eight wetlands were sampled in the Sinos River floodplain, four natural and four mined. In the laboratory, four field sediment samples were incubated for zooplankton hatching in five treatments comprising sediments from: mined wetlands, natural wetlands, and three treatments containing mined sediments added with low (5%), medium (20%) and high (40%) quantities of sediment from natural wetlands. Hatching consisted of 61 individuals distributed across eight zooplankton taxa. Copepod nauplii were the most abundant (31.1%) followed by Epiphanes sp. (29.5%) and Ovalona glabra (16.4%). While natural wetlands provided 42.6% of the hatched zooplankton, mined wetlands had just 6.5%. Zooplankton richness and abundance were higher in natural wetland sediments compared with mined and added sediment wetlands. To some degree, the sediment soil donation from natural to mined wetlands was considered viable. As long as prior studies are performed to test the size and quality of the dormant banks present in the sediment of candidate donor wetlands, sediment from donor wetlands may aid in the establishment of a more diverse community in disturbed systems.

     

飞来峡水库蓄水初期营养状态及浮游生物分布特征

于2000年丰水期和枯水期调查分析了新建河流型水库-飞来峡水库在蓄水初期的营养状态及浮游生物特征。结果表明:水库处于营养累积高峰期,已开始回落,但流域上游大量含磷废水使水库中磷含量继续上升,目前属于中营养型。共记录到浮游植物29种(属),以蓝藻门、绿藻门、硅藻门种类较多,其中丰水期以蓝藻和绿藻为主,枯水期是硅藻占优势,除大坝附近外,浮游植物两个季节密度变化不大,为0.39×10⁶cells·L^-1.浮游动物53种(属),其中包括僧帽溞和透明薄皮溞两种嗜寒性种类,丰度为52ind.·L^-1,枯水期高于丰水期,数量以轮虫和无节幼体为多。     

Zooplankton Composition and Ecology in Western Boreal Shallow-water Wetlands

Zooplankton are a functionally important but poorly studied component of western boreal forest (WBF) wetland ecosystems. To characterize patterns in zooplankton abundance and composition an exploratory study of 24 shallow-water wetlands in northern Alberta, Canada was carried out over the summers of 2001 and 2002. Results suggest zooplankton communities in WBF wetlands tend to exist as: (1) small-cladoceran dominated communities, (2) larger sized cladoceran (e.g. Daphnia) dominated communities, or (3) communities composed primarily of rotifers and/or other crustacean zooplankton. The presence/absence of brook stickleback (Culea inconstans) was the factor most strongly linked to zooplankton structure with small cladocerans tending to dominate in wetlands with stickleback. In fishless wetlands, communities dominated by medium-large sized cladocerans tended to correspond with low-chlorophyll/high-submerged aquatic vegetation (SAV) conditions. Conversely, communities composed of rotifers and other crustaceans were associated with high-chlorophyll/low-SAV states. Macro-invertebrate predator abundance was not strongly linked to patterns in zooplankton composition suggesting macro-invertebrate predation is not a significant factor influencing zooplankton structure in fishless wetlands. Results suggest activities that spread stickleback (e.g. ditching) or inhibit development of macrophyte-dominated/clear-water conditions (e.g. nutrient loading) may seriously alter the zooplankton community structure, and thereby the functional ecology, of these valuable wetland ecosystems.     

Spatial patterns and relationships between phytoplankton, zooplankton and water quality in the Saimaa lake system, Finland

The interactions between phytoplankton and zooplankton were studied in two large lakes in the Saimaa lake system, Finland. Both are subjected to substantial waste water loading, and exhibit a clear trophic gradient between the loaded and unloaded areas. The phytoplankton and zooplankton were compared in terms of composition, abundance and biomass at 34–39 stations located in different parts of the lakes. At least four mechanisms were thought to affect the composition of plankton communities: (1) the amount of nutrients (trophic gradient), (2) grazing of algae by herbivores, (3) the effect of the algal species composition on feeding by zooplankters (large, colonial algae in the more loaded parts of the lakes) and (4) the regeneration and reorganization of nutrients.     

Macrophytes moderate the taxonomic and functional composition of phytoplankton assemblages during a nutrient loading experiment

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Controlling factors of phytoplankton assemblages in wetlands: an experimental approach

The aim of this work is to answer some questions like: what factors control the phytoplankton assemblage? What factor or factors are perturbing the assemblage? What factors are driving or maintaining the stability? Are the different responses to the control factors dependent on the hierarchy level? For that, we tested experimentally the influence of herbivory, planktivory, nutrients and sediment on phytoplankton assemblages and its stability from a hypertrophic wetland (Las Tablas de Daimiel National Park, Spain) in three microcosm experiments. The study of the steady state phytoplankton assemblages in this perturbed system could point out some underlying processes instead of competition. The presence of planktivorous fish and the different composition of zooplankton have minor importance in phytoplankton composition. Conversely, sediment is of paramount importance, promoting a more diverse phytoplankton assemblage. When sediment or nutrient pulses are absent, phytoplankton become dominated by slow-growing algae, present but not dominant in the studied wetland community. We suggest that alternate states of phytoplankton assemblages in a eutrophic wetland occur as a sequence of substitutions persistently altered by perturbations, thanks to the close coupling with sediment, and that possibly trophic relationships are irrelevant.     

Biological diversity versus risk for mosquito nuisance and disease transmission in constructed wetlands in southern Sweden

In southern Sweden, many wetlands have been constructed, and maintaining or increasing biological diversity is often included in the aims. Some wetlands are constructed near human settlements, thus raising the problem of wetlands being associated with mosquitoes (Diptera: Culicidae). Increased biodiversity (including mosquito diversity) is considered desirable, whereas mosquito nuisance from a human point of view is not. Adult mosquito abundance, diversity and species assemblages of constructed wetlands were compared to natural wetlands. The potential of constructed wetlands for mosquito nuisance and transmission of mosquito-borne viruses was evaluated. The study areas included five constructed and four natural wetlands. Mosquito abundance and species richness were higher in the natural than in the constructed wetlands, and showed a positive correlation with wetland size. Mosquito species assemblages formed three clusters, which were not explained by origin, size and water permanence of wetlands. In a redundancy analysis, however, mosquito faunas showed significant relationships with these variables, and size and origin of wetlands were most important. Major nuisance species (multivoltine species feeding on mammals and laying eggs on soil) were found in all wetlands, although in relatively low numbers. Risk assessment for Sindbis virus transmission showed moderate risk for two constructed wetlands near human settlements. It is concluded that small size of constructed wetlands has the advantage of low mosquito numbers from a human point of view. The use of functional groups is recommended as a tool for presenting mosquito data to the public, and for helping communication between scientists and administrative decision makers.     

Competing Effects of Toxin-Producing Phytoplankton on Overall Plankton Populations in the Bay of Bengal

The coexistence of a large number of phytoplankton species on a seemingly limited variety of resources is a classical problem in ecology, known as ‘the paradox of the plankton’. Strong fluctuations in species abundance due to the external factors or competitive interactions leading to oscillations, chaos and short-term equilibria have been cited so far to explain multi-species coexistence and biodiversity of phytoplankton. However, none of the explanations has been universally accepted. The qualitative view and statistical analysis of our field data establish two distinct roles of toxin-producing phytoplankton (TPP): toxin allelopathy weakens the interspecific competition among phytoplankton groups and the inhibition due to ingestion of toxic substances reduces the abundance of the grazer zooplankton. Structuring the overall plankton population as a combination of nontoxic phytoplankton (NTP), toxic phytoplankton, and zooplankton, here we offer a novel solution to the plankton paradox governed by the activity of TPP. We demonstrate our findings through qualitative analysis of our sample data followed by analysis of a mathematical model.     

三江平原典型沼泽湿地螺类组成生态指示

螺类作为湿地的重要生物类群,对环境变化响应敏感,这使得螺类成为潜在的环境指示物种。为了研究中国东北沼泽湿地不同类型湿地螺类群落结构的差异以及螺类作为不同类型湿地指示物种的可能,在2014年9月和2015年5月对小叶章沼泽化草甸湿地、臌囊苔草湿地、毛苔草湿地、漂筏苔草湿地共17个采样点进行螺类样品采集。共采集到了螺类8科13属17种4452个。研究表明,螺类以扁卷螺科Planorbidae、椎实螺科Lymnaeidae、膀胱螺科Physidae为主;4种不同类型湿地螺的种类组成不同,这些螺类的种类组成与不同类型湿地的水深、植物类型组成等湿地特征是相对应。螺类的生物多样性指数(ShannonWiener指数和Marglef指数)在不同类型湿地之间也存在一定差异,筛选了指示螺类6种,无褶螺是小叶章沼泽化草甸的指示物种,小土蜗、半球多脉扁螺和虹蛹螺是臌囊苔草湿地的指示物种,琥珀螺是毛苔草湿地的指示物种,平盘螺是漂筏苔草湿地的指示物种,这表明了螺类是沼泽湿地类型的重要指示生物。也为螺类生物多样性资源的保护、恢复和生态评价提供科学依据和资料积累。