Trophic relationships in the pelagic zone of Mondsee,Austria

Data are presented on nutrient concentrations, phytoplankton biovolume development, zooplankton composition and population dynamics, and fish from a deep, stratifying, alpine lake (Mondsee, Austria) during a three-year period between 1982 and 1984. Development of the phytoplankton is closely related to structuring events of the physico-chemical environment. Dissolved silicate and phosphorus concentrations are critical for the summer situation. During summer algal abundance is largely affected by grazing of zooplankton, but no clear-water phase was observed at the end of the spring peak of phytoplankton.Temperature and food are factors responsible for the timing and growth of the zooplankton populations. Because of close overlap in the epilimnion, exploitative and mechanical interference competition and predation by invertebrate and vertebrate predators are the main structuring forces acting on the zooplankton community, and hence influence phytoplankton indirectly.     

Phytoplankton Community Structure in the Drainage Network of a Mediterranean River System (Aliakmon,Greece)

Phytoplankton structure was studied in Aliakmon river basin in April (highflow) and September (lowflow) 1995 in 29 sampling sites. Abundance and biomass were generally low and ranged considerably between sites. Benthic diatoms contributed greatly to the suspended algal assemblages whereas trends of potamoplankton development were observed downstream. Limnoplankton and especially chlorophytes developed in the areas where lentic conditions prevailed. The nature of changes in phytoplankton seemed to be both longitudinal and temporal. Multivariate techniques revealed that areas with distinctive morphology, hydrology and anthropogenic inputs tended to have similar phytoplankton composition although no simple relation with physico-chemical factors can be shown. Human impact was more obvious on phytoplankton at the lowflow period. Generally, discharge played a significant role to the structure of phytoplankton communities.     

Possible relation between phytoplankton numbers and Saprolegnioid fungi in Shatt Al-Arab near Basrah,Iraq

This study, carried out in Shatt Al-Arab river near Basrah, Iraq, reports a close negative (inverse) relation between phytoplankton numbers and decomposing fungi belonging to the family Saprolegniaceae (Oomycetes). This relation seems to depend on substrate relationship and antagonism. In addition the role of other physico-chemical factors, pH, temperature and salinity has been discussed.     

The seasonal cycle of the phytoplankton in the coastal waters of Ghana

Seasonal changes in the phytoplankton at four depths off Tema, Ghana were investigated between September 1973 and November 1974. The physico-chemical factors show that there are two marine seasons, the season of major upwelling (July–October), characterized by low water temperatures (< 25°C), high salinity (> 35) and high nutrient levels, and a non-upwelling period (November–June) when water temperatures are higher and salinity and nutrients are lower. The latter marine season is broken by a small, unpredictable upwelling (December-January). Phytoplankton cell counts are high (> 1000 × 103 cells/1) during the major upwelling period and can be very low (< 2 × 10³ cells/1) during the non-upwelling period. Dinoflagellates form the main components of the phytoplankton population during the nonupwelling period and diatoms form the dominant components at other times. There is a close relationship between the physicochemical factors and the phytoplankton population especially during the major upwelling period. For example there is a good correspondence between the peaks in phytoplankton numbers and low levels of nutrients such as silicate, nitrate and phosphate with the reverse taking place at other times.     

2006年夏季南黄海浮游植物叶绿素a分布特征及其环境调控机制

根据2006年夏季南黄海生态调查资料,分析了浮游植物现存量(叶绿素a)的空间分布特征及其主要环境调控机制.结果表明:南黄海浮游植物叶绿素a浓度范围为0.07～12.17 mg/m3,平均值为1.42 mg/m3;浮游植物叶绿素a平面分布呈近岸混合区高于外海层化区的特征,总体上随水体盐度和营养盐梯度的变化而变化,其中浅海陆架锋区对浮游植物有明显的聚集作用,垂直结构中层化区叶绿素次表层最大值现象明显,且最大值的深度和量值具有明显的区域差异;叶绿素a浓度与主要环境因子的相关性分析表明,在较大空间尺度上营养盐是浮游植物的主要调控因子,温度、光照和浮游动物摄食等也在一定空间和程度上对浮游植物的生长产生影响.     

浙南大罗山天河水库浮游植物群落结构的季节变化及对水质的指示作用

为了探究浙南地区山区水库浮游植物群落结构的季节变化及水质状况,于2019年2月-2020年1月对位于温州大罗山天河水库的浮游植物群落结构和水体理化因子进行了调查分析.结果 表明:天河水库浮游植物隶属于7门60属89种,全年浮游植物平均丰度为2.02×105 cells·L-1,年均生物量为0.26 mg·L-1.硅藻门...     

Studies on the Primary Production of Phytoplankton in Suraha Lake (Ballia,India)

The paper describes the seasonal variation in the rate of phytoplankton primary production in Suraha Lake – a large shallow water body – in relation to certain physico-chemical parameters and the abundance and composition of the phytoplankton over a period of two years.     

Ecological restoration and factors regulating phytoplankton community in a hypertrophic shallow lake,Lake Taihu,China

A restoration program for the control of cyanobacterial blooms and the re-establishment of submerged macrophytes was conducted in Meiliang Bay of Lake Taihu since 2003. The effect of this ecological projects on plankton community and water quality, and factors regulating phytoplankton community were investigated in 2005. In general, some improvements of water quality occurred in the ecological restoration region, especially in the region of restoring aquatic macrophytes, where we detected significant reduction of nutrients. However, it seems the abundance of phytoplankton cannot be effectively control by the present ecological engineering. The phytoplankton abundance was high in the target restoration zone. Results of CCA and correlation analysis indicate that the phytoplankton community was mainly controlled by physico-chemical factors. Cyanobacteria species were positively related with pH, temperature, TP and TSS, while negatively related with TN, TN/TP and conductivity. The most discriminant variable was TN/TP, which explained 15% of the total variance of phytoplankton. However, TN was more important for the fluctuation of TN/TP than TP. It suggested that TN may be the ultimate factor controlling the phytoplankton community in Lake Taihu. Variation partitioning analysis showed that the pure contribution of crustacean was low for the variation of phytoplankton, suggesting that top-down control by crustacean zooplankton was weak in Lake Taihu. In general, this study suggested the reduction of nutrient load should be more important than top-down control using zooplankton for the ecosystem restoration in Lake Taihu.     

Phytoplankton primary productivity seasonality and changes in a small African lake,Lake Hora-Kilole,Ethiopia

The seasonality of primary productivity by phytoplankton in relation to physico-chemical and biological variables was studied in Lake Hora-Kilole from August 2007 to May 2008. In 1989, the Mojo River was temporarily diverted to flow into the lake, which substantially changed its physico-chemical conditions and the composition of the phytoplankton. Primary productivity was controlled primarily by soluble reactive phosphorus (SRP), ammonia (NH₃), temperature and euphotic depth (Z_eu). The light-saturated rate of photosynthesis (A_max) varied from 370 to 3 843?mg O₂ m^?3 h^?1 with the maximum value corresponding to the seasonal maximum of phytoplankton biomass. Compared to the period before the diversion of the river, A_max was reduced by more than ninety-fold in early 1990s and by less than five-fold in 2007 and 2008. Similarly, average phytoplankton chlorophyll a was reduced by more than 2.5 × in the early 1990s and to less than 50% in 2007 and 2008. This highlights the importance of the diversion river water on the physico-chemical and biological environment of the lake.     

The key role of the chemolimnion in meromictic cenotes of the Yucatan Peninsula,Mexico

This study tests the ecological and physico-chemical effect of sharp density boundaries of meromictic lakes. The investigation was carried out in Nohoch Hol, an anchialine meromictic cenote situated 2.0 km inland from the Caribbean coast of the Yucatan Peninsula, Mexico. In situ physico-chemical parameters were recorded with a water quality datalogger at depth intervals of 0.5 m. In addition, seven water samples for determination of nutrients, bacterioplankton and phytoplankton in the water column were obtained using SCUBA. Bacterioplankton and phytoplankton densities are low, with concentrations consistent with the oligo- to ultraoligotrophic status of Nohoch Hol indicated by the low nutrient concentrations. The phytoplankton was dominated by the chlorophyte Scenedesmus. Maximum concentrations of bacterio- and phytoplankton were found at 10.0 m depth, the top of the chemolimnion. The similarity analysis clustered the samples in three defined groups: (a) the mixolimnion, (b) the mid- and bottom of the chemolimnion and the monimolimnion, and (c) the top of the chemolimnion. The principal component analysis explained over 85% of the total variance in two components (PC). PC1 was related to turbidity and the aggregation of the chlorophytes at the top of the chemolimnion. PC2 was related to dissolved oxygen and the accumulation of filamentous and total bacteria also at the top of the chemolimnion. The top of the chemolimnion acts as a boundary within the water column to the exchange of dissolved and particulate matter between the mixo and the monimolimnion and as an ecological zone with a crucial role in the biogeochemistry of Nohoch Hol.     

A Compositional and Structural Analysis of Phytoplankton in Lake Khurpatal, (U.P.), India

The phytoplankton community in Lake Khurpatal (Kumaun Himalya), India, was analyzed in relation to physico-chemical variables. Phytoplankton biomass ranged from 2.7 to 20.0 g m⁻³ in the euphotic zone of the lake. Dinoflagellates monopolized the algal community with a mean annual contribution of 94.5 % to the total phytoplankton biomass. The community coefficient used to quantify the seasonal changes in algal population reflected the fact that successional episodes were not very significant, the percentage similarity among the consecutive algal samples ranging from 47.8 to 89.9 %. The phytoplankton community was characterized by low species richness, low equitability and species diversity. Various ecological characteristics of the community are discussed and the phytoplankton biomass is also compared with that of some tropical and temperate lakes.     

Decoding Size Distribution Patterns in Marine and Transitional Water Phytoplankton: From Community to Species Level

Understanding the mechanisms of phytoplankton community assembly is a fundamental issue of aquatic ecology. Here, we use field data from transitional (e.g. coastal lagoons) and coastal water environments to decode patterns of phytoplankton size distribution into organization and adaptive mechanisms. Transitional waters are characterized by higher resource availability and shallower well-mixed water column than coastal marine environments. Differences in physico-chemical regime between the two environments have been hypothesized to exert contrasting selective pressures on phytoplankton cell morphology (size and shape). We tested the hypothesis focusing on resource availability (nutrients and light) and mixed layer depth as ecological axes that define ecological niches of phytoplankton. We report fundamental differences in size distributions of marine and freshwater diatoms, with transitional water phytoplankton significantly smaller and with higher surface to volume ratio than marine species. Here, we hypothesize that mixing condition affecting size-dependent sinking may drive phytoplankton size and shape distributions. The interplay between shallow mixed layer depth and frequent and complete mixing of transitional waters may likely increase the competitive advantage of small phytoplankton limiting large cell fitness. The nutrient regime appears to explain the size distribution within both marine and transitional water environments, while it seem does not explain the pattern observed across the two environments. In addition, difference in light availability across the two environments appear do not explain the occurrence of asymmetric size distribution at each hierarchical level. We hypothesize that such competitive equilibria and adaptive strategies in resource exploitation may drive by organism’s behavior which exploring patch resources in transitional and marine phytoplankton communities.     

Dynamics of ice algae and phytoplankton in Frobisher Bay

Summary Vertical and seasonal variations of ice algae and phytoplankton were studied in relation to their physico-chemical environments in Frobisher Bay from 1979 to 1986. The biomass, estimated by both chlorophyll a concentrations and cell counts, was greater in the ice algae than in the phytoplankton in the underlying sea-water during winter and spring. Algal distribution in the sea ice varied vertically and seasonally, while in the underlying water column the phytoplankton distribution was much less variable. The ice algal bloom occurred at the bottom of the ice, particularly in the lower 5 cm during late spring, while the phytoplankton bloom took place at depths between 1 and 10 m during early summer after the ice bloom was over. The community structure of the ice algae changed from pennate to centric diatoms as the ice melted. The centrics dominated through the fall, and then decreased as the pennates increased in dominance when the ice formed again in winter. Species diversity and number were greater in the sea ice than in the seawater, but they were similar vertically within each habitat. The evenness of the species distribution did not vary with ice thickness or water depth. Species composition, abundance and dominance of ice algae and phytoplankton continually change both vertically and seasonally. The differential abilities of the species to attain maximal growth rates under various environmental conditions may result in species succession. Evidence is given for the major role of environmental factors regulating the dynamics of ice algae and phytoplankton.     

Classification and ordination of profundal macroinvertebrate communities in nutrient poor, oligo-mesohumic lakes in relation to environmental data

SUMMARY. 1. Profundal macroinvertebrates and water chemistry of sixty-eight nutrient poor, poorly buffered lakes were sampled in 1983 or 1986. Assemblages of profundal zoobenthos were classified using two-way indicator species analysis (TWINSPAN), ordinated by canonical correspondence analysis (CCA), and related to physico-chemical factors using CCA. discriminant analysis, and regression.
2. 90% of zoobenthos (TWINSPAN) groups were classified correctly using discriminant analysis. Depth (Function 1), soluble reactive Si(OH)₄ and HCO₃, -(2), and phytoplankton biovolume and pH (3) were the strongest correlates with the three discriminant functions.
3. Regression analysis showed that depth, KmnO₄, consumption, and phytoplankton biovolume were the best estimators of zoobenthos biomass in the profundal.
4. Multivariate analyses showed species assemblages amongst the profundal zoobenthos to be good indicators of lake type, particularly depth, pH, and phytoplankton biovolume.     

Polyphenolics and Energy Content in Phytoplankton: Evidence from a Freshwater Lake

Investigation was carried out in the ancient man-made, shallow, freshwater lake, Lake Krishnasayer, at Burdwan (23°16′N, 87°54′E), India, to note the variations in physico-chemical parameters, nutrients, phytoplankton communities, concentration of phenols and energy content in phytoplanktons during January–December 2006. The lake was represented by 16, 15, 2 and 17 genera of Cyanophyceae, Chlorophyceae, Euglenophyceae and Bacillariophyceae, respectively with significant variation in relative abundance as was revealed through Discriminant Analysis. Wilk’s λ values indicate that nitrate, phosphate, dissolved chlorides and silica, and phenol content were significant (P < 0.05) predictor for such differences. PCA analysis yielded three components explaining more than 68 % of the variations in the data on physico-chemical parameters, nutrients, phenol concentration and energy content of total phytoplankton. The interactions of the environmental variables contribute significantly to the observed variations in the phenol and energy content of the phytoplankton. However, the phenomenon of temporal variation in the total phytoplankton and energy content is accounted as a function of nitrate, phosphate-phosphorous, silicate and organic carbon levels. It is apparent that this quality of phytoplanktons varied with the seasons and thereby influencing the amount of phenol and energy content in the engulfing phytoplanktons. Therefore, adequate allocation is needed regarding nutritional status of phytoplanktons, in respect to the dietary need of aquaculture programme in practice.     

Nitrogen cycling in coastal marine ecosystems

It is generally considered that nitrogen availability is one of the major factors regulating primary production in temperate coastal marine environments. Coastal regions often receive large anthropogenic inputs of nitrogen that cause eutrophication. The impact of these nitrogen additions has a profound effect in estuaries and coastal lagoons where water exchange is limited. Such increased nutrient loading promotes the growth of phytoplankton and fast growing pelagic macroalgae while rooted plants (sea-grasses) and benthic are suppressed due to reduced light availability. This shift from benthic to pelagic primary production introduces large diurnal variations in oxygen concentrations in the water column. In addition oxygen consumption in the surface sediments increases due to the deposition of readily degradable biomass. In this review the physico-chemical and biological factors regulating nitrogen cycling in coastal marine ecosystems are considered in relation to developing effective management programmes to rehabilitate seagrass communities in lagoons currently dominated by pelagic macroalgae and/or cyanobacteria.     

Comparative limnology of nine lakes of Jammu and Kashmir Himalayas

Two lakes in the lower Siwalik Himalayas, five in the Kashmir valley and two situated in the high mountains of the Kashmir Himalayas were investigated for their physico-chemical and biological features. The lakes, differing significantly in their morphology and in thermal behaviour, rank from the subtropical monomictic to the dimictic type. The lakes at high altitudes (> 3000 m) have very low electric conductivity which increases with the decrease in altitude. The most dominant ions in water are calcium and bicarbonate. The macrophytic vegetation of the lakes does not show any definite relationship either with altitude or with physico-chemical milieu. In the lakes with low fertility the phytoplankton is dominated by diatoms and Chlorophyceae but in eutrophic lakes Cyanophyceae predominate. The zooplankton population of the lakes is mainly comprised of rotifera. On the basis of general limnological features and the rates of phytoplankton production most of the lakes may be categorized either as eutrophic or in the process of rapid evolution. Only one lake is oligotrophic.     

Phytoplankton Analysis in Lake Sat Tal (U.P.), India

Species composition and periodicity of phytoplankton were studied in relation to various physico-chemical parameters over a period of 18 months in the two basins of Lake Sat Tal. Taxonomic analysis led to 54 species. Phytoplankton density in the euphotic zone ranged from 0.33 × 10⁵ to 4.12 × 10⁵ cells I-¹ in the western basin (WB) and 1.31 × 10⁵ to 6.05 × 10⁵ cells I-¹ in the eastern basin (EB). The dinoflagellates (Peridinium willei, P. cinctum, Gymnodinium fuscum) which were relatively insignificant concerning number reached very high values concerning biomass, contributing 89 % and 92 %, respectively, to the total phytoplankton standing stock. Various factors as rainfall, light, temperature, organic matter, nutrients (particularly PO₄-P), silicate, were observed to play an important role in the periodicity of phytoplankton. Similarity coefficients revealed that the algal population was not very homogenous all the year round with similarities between consecutive samples ranging from 16 % to 77 % in WB and 21 % to 76 % in EB.     

On the phytoplankton of Awba reservoir, Ibadan, Nigeria

The physico-chemical characteristics and phytoplankton of Awba reservoir in the University of Ibadan, Nigeria, were monitored to determine the impact of eutrophication on phytoplankton composition. The principal component analysis identified three major components influencing the physicochemistry of the water, namely trace metals, dissolved oxygen and ionic composition. Comparative analysis with a previous study showed a phenomenal increase in zinc, copper and iron levels over a 10-year period. Furthermore, the ferruginous nature of the soil contributed to the high levels of iron which exceeded the World Health Organization Standards for drinking water quality. The most abundant phytoplankton species was Microcystis aeruginosa which has been implicated in toxic blooms in freshwaters. The conditions favouring cyanophyte blooms and their implications are discussed.     

三峡库区浮游生物群落DNA结构与水体理化因子的分析

本文对三峡水库大坝至香溪河段所设A、B、C、D、E、F和G等7个站点浮游生物群落DNA进行了RAPD分子生物学研究,并分析了其与水体理化因子的关系。各站点间RAPD研究表明：D和E首先聚到一组, 然后与A聚到一起, 最后与C聚成一大类;B和F聚成一大类;而站点G独自归于一类。而理化因子聚类结果显示：B首先与C聚为一小类,再与D聚到一起,然后与G、F聚成的小类聚为一类,而E与A分别单独归为一类。比较发现,RAPD聚类结果中相距较近的站点在理化因子聚类中显示为相距较远的站点（如站点A、C、D、E之间）,而在RAPD聚类中相距较远的站点在理化因子聚类中显示为相距较近的站点（如站点B、F分别与G之间）,这可能因为它们之间存在负相关性,也可能部分因为试验条件本身所造成的误差。为确定浮游生物DNA指纹结构与理化因子的关系提供了新的信息,进而为建立一种新的水质评价体系积累了理化因子的一些背景资料。