Diversity and succession of the phytoplankton in a small lake over a two-year period

Phytoplankton in the small central Finnish lake, Vasikkalampi, was studied over a two-year period by weekly sampling simultaneously with monitoring of physical and chemical properties of water, solar radiation energy and zooplankton. In the present paper, the fluctuations in phytoplankton diversity were studied in relation to environmental factors. The special aim for the study was to detect a relation between environmental disturbances and phytoplankton diversity.     

Influences of the lowland river Spree on phytoplankton dynamics in the flow-through Lake Müggelsee (Germany)

The influences of imports of nutrients and planktonic algae from the River Spree on the dynamics of phytoplankton were examined in the shallow, eutrophic Müggelsee, which has a retention time of only 42 days. Phytoplankton biomass and nutrient concentrations were measured in both the lake and its inflow from 1980–1990. On a long-term average, mean biomass as well as vitality of most dominant phytoplankton populations in the lake were not significantly different from those in the river. Nevertheless, during distinct periods the external rates of biomass change of single lake populations (due to dilution or enrichment) were as high as the lake internal ones. The import of inocula populations from the river probably induced the formation of the typical community structure in the lake. Growth and decay of phytoplankton populations in the river strongly influenced the load of dissolved nutrients and thus indirectly the dynamics of planktonic algae in the downstream lake. For example, intensive assimilation of phosphorus by riverine algae in spring intensified the P-shortage and supported possible P-limitation of algal growth in the lake at that time. In years with high vernal biomass of centric diatoms in the river, and thus diminished import of dissolved silicon, the growth of diatoms was suppressed and that of cyanobacteria was favoured in the lake during summer.     

A study of Lough Corrib,western Ireland and its phytoplankton

During 1980/1981, a twelve month study was carried out on the phytoplankton of Lough Corrib, a large freshwater lake in western Ireland. Cell counts indicated low phytoplankton productivity and this was reflected in low chlorophyll a values and high Secchi readings. Diatoms predominated in spring and were succeeded by blue-green algae in late summer. The spring diatom crop was apparently limited by either silicate or nitrogen. Mineral uptake by rooting macrophytes and benthic algae and phosphate recycling as a result of bottom sediment disturbance may be important elements in the nutrient cycling regime of the lake. Differences in morphology between the upper and lower basins of the lake are reflected, to some extent, in species composition and areal productivity.     

Temperature,growth and seasonal succession of phytoplankton in Lake Baikal,Siberia

• 1 Growth rates of two dominant Lake Baikal phytoplankton, the winter diatom Aulacoseira baicalensis and the summer cyanobacterium Synechocystis limnetica, were measured in the laboratory under varied temperature and light regimes to determine the potential role of these abiotic factors in seasonal species succession in the lake.
• 2 Aulacoseira baicalensis grew best at low temperature and not at all above 8 °C. Its maximum instantaneous growth rate was 0.15 d^‐1 recorded at 2–3 °C. Cells grew faster as temperature decreased, apparently in contrast to conventional Q₁₀‐based temperature‐growth relationships.
• 3 The picoplankter Synechocystis limnetica did not grow at 2–3 or 5–6 °C, but grew at a rate of 0.24 d^‐1 at the highest incubation temperature of 17 °C. Maximum growth rate was 0.35 d^‐1 at 8 °C.
• 4 Saturation irradiances (I_k) for growth of Aulacoseira baicalensis and Synechocystis limnetica were near pre‐acclimation values of 40 µmol m^‐2 s^‐1. At temperatures conducive to growth, both phytoplankters grew at all irradiances tested, except for A. baicalensis which would not grow at values above 300 µmol m^‐2 s^‐1 at 8 °C.
• 5 We conclude that temperature is a major driving force for the seasonal succession of species in Lake Baikal. Other factors, including vertical mixing of the water column and grazing by zooplankton, may also play important roles.

     

Nutrient limitation of phytoplankton growth in Waquoit Bay, Massachusetts, USA: a nutrient enrichment study

We conducted nutrient enrichment experiments and field sampling to address three questions: (1) is there nutrient limitation of phytoplankton accumulation within an estuary whose waters are exposed to relatively high nitrogen loading rates, (2) where in the salinity gradient from fresh to seawater (0 to 32‰) is there a shift from phosphorus to nitrogen limitation of phytoplankton accumulation, and (3) is there a seasonal shift in limiting function of phosphorus and nitrogen anywhere in the estuarine gradient. Nitrogen and phosphorus enrichment experiments in the Childs River, an estuary of Waquoit Bay, Massachusetts, USA, showed that the accumulation of phytoplankton biomass in brackish and saline water was limited by supply of nitrate during warm months. The effects of enrichment were less evident in fresh water, with short-lived responses to phosphate enrichment. There was no specific point along the salinity gradient where there was a shift from phosphorus- to nitrogen-limited phytoplankton accumulation; rather, the relative importance of nitrogen and phosphorus changed along the salinity gradient in the estuary and with season of the year. There was no response to nutrient additions during the colder months, suggesting that some seasonally-varying factor, such as light, temperature or a physiological mechanism, restricted phytoplankton accumulation during months other than May-Aug. There was only slight evidence of a seasonal shift between nitrogen- and phosphorus-limitation of chlorophyll accumulation. Phytoplankton populations in nutrient-rich estuaries with short flushing times grow fast, but at the same time the cells may be advected out of the estuaries while still rapidly dividing, thereby providing an important subsidy to production in nearby deeper waters. This revised version was published online in August 2006 with corrections to the Cover Date.     

Phytoplankton succession in Lake Valencia,Venezuela

Phytoplankton counts and supporting physical and chemical data were taken on Lake Valencia, Venezuela, over a five-year interval. The data are used to test the validity of a successional paradigm for class-level taxa. According to the paradigm, formulated from previous studies of Lake Lanao, Philippines, and from data on temperate lakes, the order of taxa from early to late succession is: diatoms, chlorophytes, blue-green algae, dinoflagellates. A successional episode is considered to begin when stability of a water column is restored after deep mixing. As the episode progresses, there is a steady decrease in concentration of the limiting macronutrient (in this case, N). In a test of the validity of the paradigm for Lake Valencia, dates of exceptional population increase or decrease were obtained for each taxon. Since nitrate concentration declines steadily as succession progresses, the entry of a given taxon into the successional sequence is indicated quantitatively by the mean nitrate concentration on dates of exceptional increase in population density, and exit from the successional sequence is indicated by mean nitrate concentration on dates of exceptional population declines. The successional position of each major taxon, bounded by its entry and exit in the sequence, can be mapped on the complete spectrum of nitrate concentrations observed in the lake. For Lake Valencia, the nitrate mapping procedure agrees exactly with the predictions based on the successional paradigm. Conformance of Lake Valencia phytoplankton with predictions made a priori suggests that there is a generalized pattern in the phytoplankton succession of the mixed layers of temperate and tropical lakes.     

营养盐加富和鱼类添加对浮游植物群落演替和多样性的影响

浮游植物是水体生态系统敞水区最重要的初级生产者,其组成与多样性反映了群落的结构类型和存在状态。通过围隔实验,模拟水库春季发生的营养盐加富和鱼类放养的干扰,分析在这两种干扰下的浮游植物群落演替过程中优势种和稀有种的变化,并通过以丰度与生物量为变量的香农和辛普森多样性指数的计算,分析浮游植物群落演替过程中的多样性变化特征。结果表明,营养盐加富干扰下的浮游植物群落的优势种变化和演替更为明显,营养盐加富与鱼类添加对浮游植物群落多样性变化的影响符合中度干扰理论。在优势种优势度变化较大的浮游植物群落演替过程中,多样性指数与浮游植物生物量有较高的负相关性。在浮游植物群落演替过程中,香农和辛普森多样性指数的变化趋势基本一致,采用丰度与生物量为变量的两种多样性指数的计算结果对实验系统中浮游植物群落多样性的分析结果没有明显的影响。     

Seasonal succession of phytoplankton and its diversity in two highly eutrophic lakes with different conditions of stratification

Seasonal succession of phytoplankton biomass, its diversity and its photosynthetic activity in two highly eutrophic lakes have been compared. In order to test the intermediate disturbance hypothesis, the lakes have been chosen with almost the same level of trophy but different conditions of stratification, through two ice-free periods of open water with different weather conditions.High phytoplankton diversity throughout the period of investigation was characteristic for the shallower Lake Lobardzu. The number of species here was usually more than 30 and the Shannon diversity changed from 1.2 to 4.2. Owing to the frequent external disturbances, periods characterized by autogenic succession with establishing dominance and declining diversity alternated with periods of biomass reduction and rises of diversity and photosynthetic activity. In the warmer summer of 1983, with more intense warming of bottom layers and predominance of blue-greens, phytoplankton biomass was higher and diversity lower than in the cold summer of 1982.In stratified Lake Rudusku, phytoplankton diversity and number of species were usually much lower. During the long summer stratification up to three-four dominant species of blue-greens and dinoflagellates become established and competitive exclusion leading to low diversity advanced. Some changes in biomass and diversity, were caused by zooplankton activity.     

金河湾城市湿地浮游植物功能类群演替及驱动因子

于2015年春(5月)、夏(8月)、秋(10月)三季,在金河湾湿地4类水体共设置12个采样点对浮游植物功能类群演替及与水环境变量关系进行分析。研究期间共鉴定浮游植物376个种,隶属于8门10纲19目19科101属。浮游植物种类组成主要以硅藻门(39.62%)和绿藻门(35.64%)为主,其次裸藻门(10.11%)和蓝藻门(9.84%)的藻类所占比例较高,甲藻门、隐藻门、金藻门和黄藻门所占比例较低。调查期间金河湾湿地浮游植物细胞丰度季节间差异显著(P0.05),整体上呈现夏季秋季春季的规律。春、夏、秋三季共划分20个不同的功能类群,双因素方差分析(Two-way ANOVA)和单因子交叉相似性检验(One-way ANOSIM)表明:代表性功能类群在季节间演替明显(P0.05),群落构成差异显著(P0.01)。SIMPER分析指出,S2/H1/B/D/Lo/X1/MP是引起金河湾湿地各季节之间浮游植物群落结构差异的主要贡献类群。通过代表性功能类群和10个水环境变量的典范对应分析(CCA)探索环境变量与功能类群演替的关系。经分析,总氮(TN)是驱动金河湾湿地浮游植物功能类群演替的主要环境变量,电导率(SpCond)、pH与功能类群演替密切相关。     

Seasonal Dynamics of Benthic and Planktonic Algae in a Nutrient‐Rich Lowland River (Spree,Germany)

We studied chlorophyll a (chl. a), biovolume and species composition of benthic algae and phytoplankton in the eutrophic lower River Spree in 1996. The chl. a concentration was estimated as 3.5 (2.7–4.5) µg/cm² for epipsammon, 9.4 (7.4–11.9) µg/cm² for epipelon and 6.7 (5.7–7.8) µg/cm² for the epilithon (median and 95% C. L.). The mean total biomass of benthic algae was significantly higher (6.0 µg chl. a/cm²) than the areal chl. a content of the pelagic zone (1.6 µg chl. a/cm²). Although certain phytoplankton taxa were abundant in the periphyton, benthic taxa generally dominated the assemblages. Seasonal dynamics of benthic algae were probably controlled by light and nitrate supply (sand), discharge fluctuations (sand, mud) and invertebrate grazing (stones). This paper shows the importance of benthic algae even in phytoplankton‐rich lowland rivers with sandy or muddy sediments. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Seasonal pattern of ammonium (methylamine) uptake by phytoplankton in an oligotrophic lake

Our primary objective was to determine if a relationship existed between seasonal change in phytoplankton and high affinity for (K _m) or uptake rates (V _maX) of ammonium which might explain seasonal phytoplankton succession in oligotrophic ecosystems. We measured ammonium uptake using [¹⁴C]-methylamine and estimatedK _m andV _max using Hanes Plots at 2-week intervals during 6 months of thermal stratification in Mountain lake, Virginia (37° 22 N, 80° 32 W). Community composition, nutrient levels, and other variables were determined in all uptake experiments. A second objective was to determine if ammonium was preferentially utilized over nitrate and to characterize further the ammonium transport system.V _max increased steadily from May until the end of July, each increase coinciding with major changes in the phytoplankton community. Cryptophyceans dominated in May, chlorophyceans in June and July, and cyanophyceans from the end of July to late October. With cyanophycean dominance,V _max declined until chlorophyceans reestablished dominance in late October. By contrast,K _m values increased from May to the end of July, but thereafter showed no correlation. Acetylene reduction experiments showed no nitrogen fixation during late summer and fall when blue-green algae were present. Preference for ammonium was implied also by negative nitrate reductase assays. Overall, the coincidence ofV _max andK _m values for [¹⁴C]-methylamine uptake and changing phytoplankton community structure suggests the possibility that successive algal communities may be changing as a result of specific species differences in ammonium affinity and uptake rates.     

Biological control of phytoplankton by the subtropical submerged macrophytes Egeria densa and Potamogeton illinoensis: a mesocosm study

1. In temperate regions, submerged macrophytes can hamper phytoplankton blooms. Such an effect could arise directly, for instance via allelopathy, or indirectly, via competition for nutrients or the positive interaction between submerged macrophytes and zooplankton grazing. However, there is some evidence that the positive interaction between submerged macrophytes and zooplankton grazing is less marked in warmer regions, where the interaction is less well studied, and that negative effects of higher water plants on phytoplankton biomass are weaker. 2. We carried out two consecutive mesocosm experiments in Uruguay (subtropical South America) to study the effects of two common submerged macrophytes from this region (Egeria densa and Potamogeton illinoensis) on phytoplankton biomass, in the absence of zooplankton grazing. We compared phytoplankton development between different macrophyte treatments (no macrophytes, artificial macrophytes, real Egeria and real Potamogeton). We used artificial macrophytes to differentiate between physical effects (i.e. shading, sedimentation and competition with periphyton) and biological effects (i.e. nutrient competition and allelopathy). 3. In Experiment 1, we found no evidence for physical effects of macrophytes on phytoplankton biomass, but both macrophyte species seemed to exert strong biological effects on phytoplankton biomass. Only Egeria affected phytoplankton community structure, particularly tempering the dominance of Scenedesmus. Nutrient addition assays revealed that only Egeria suppressed phytoplankton through nutrient competition. 4. We performed a second mesocosm experiment with the same design, but applying saturating nutrient conditions as a way of excluding the effects of competition for nutrients. This experiment showed that both macrophytes were still able to suppress phytoplankton through biological mechanisms, providing evidence for allelopathic effects. Our results indicate that both common macrophytes are able to keep phytoplankton biomass low, even in the absence of zooplankton grazing.     

Long-term compositional response of phytoplankton in a shallow,turbid environment,Neusiedlersee (Austria/Hungary)

Data on phytoplankton biomass and on nutrient concentrations from Neusiedler See (mean depth 1.3 m) covering more than two decades are presented. The lake underwent strong eutrophication during this period. The response of annual average phytoplankton biomass and chlorophyll-a to the increase of phosphorus concentration from 10 to > 100 µg l^-1 was moderate (7-fold increase). This is caused by light limitation of the system because of the high inorganic turbidity of the lake. Analyses of the spring, summer and autumn seasons at the generic and higher taxonomic levels show significant changes in composition of the phytoplankton community. Diatoms were more important during the pre-eutrophication phase while Chlorophyceae became most prominent during the peak of the eutrophication process. Blue-green algae, including Microcystis, became more apparent after this period. The abundance of some groups or genera, e.g. Euglena, was linked to the decline and re-appearance of submerged macrophytes in the lake. Abiotic and biotic interactions as causes for the observed changes are discussed.     

Compensation effect of phytoplankton on nutrients from a sewage outfall in summer

This paper investigates the relationship between nutrients, chlorophyll a and physical variables in the upper Saronikos Gulf, an oligotrophic marine environment south of the Greater Athens Metropolitan Area. Phosphate, silicate, ammonia, nitrite, nitrate, temperature, salinity and dissolved oxygen were determined at eight stations on 9 occasions during summer 1982. A thermocline led to the stratification of the water column and the pycnocline was related to the thermocline. The values of oxygen were more or less normal. The Eutrophication of the seawater in the vicinity of the sewage outfall was demonstrated by surface levels of chlorophyll a being forty to two hundred times above background. This parameter provides evidence for a high phytoplankton standing stock. However, there were no appreciable differences between the nutrients in the outfall area and those in the background. This suggests rapid uptake of nutrients and/or effective dispersal from the outfall.     

Seasonal dynamics of phytoplankton and phytobenthos,and associated chemical interactions,in a shallow upland lake (Malham Tarn,northern England)

Seasonal changes of phytoplankton were followed over 3 years (1985–87) in a shallow, unstratified and calcareous upland lake.The phytoplankton was of low to moderate abundance and generally dominated by phytoflagellates. Seasonality involved a winter minimum of abundance, a spring maximum of diatoms, and often brief increases in summer that included blue-greens, especially the colonial Gloeotrichia echinulata. Some components were of benthic origin. Seasonal growth of the main component of the phytobenthos, Chara globularisvar. virgata, caused a regular summer depletion in lake water of Ca²⁺ and HCO₃ ^- (alkalinity) by associated CaCO₃ deposition, and a more extreme (and unusual) depletion of K⁺. Chemical analysis of Chara biomass and of underlying sediments indicated a large benthic nutrient stock, much surpassing that represented by the phytoplankton. Growth in this biomass, and the magnitude of water-borne inputs, influenced the removals of Ca²⁺, K⁺ and inorganic N. The phytoplankton was probably limited by a low-P medium, to which co-precipitation of phosphate with CaCO₃ may have contributed. A vernal depletion of Si was probably limiting to diatom growth, and appeared to be mainly induced by benthic rather than planktonic diatoms. Examples of long-term change in composition of the phytoplankton and phytobenthos are noted and discussed in relation to the interaction of these components, nutrient enrichment, and possible alternative stable states.     

Phytoplankton succession in the euphotic zone of Lake Corlo (Northern Italy) during summer stratification

Abstract

Lake Corlo is a dammed reservoir for hydro-electrical purposes in Northern Italy. Weekly samplings were made from May to August 1985 in the euphotic layer. Two major categories, flagellates and diatoms, alternatively dominated the algal community. Flagellates prevailed with stratified conditions. The strong influence of hydraulic conditions on phytoplakton succession is emphasized.     

Succession of phytoplankton in a deep stratifying lake: Mondsee,Austria

Phytoplankton numbers, biovolume, chlorophyll-a and various physico-chemical characteristics were followed at weekly intervals in Mondsee, Austria during the year 1982. Secchi-disk transparency varied from 10 m in winter to 2 m in September. Prior to the onset of stratification phosphate-phosphorus concentration was 4 µg 1^–1 decreasing to undetectable values thereafter. Nitrate-nitrogen dropped from 590 µg 1^–1 to about 100 µg 1^–1 during the same time. The vernal bloom was dominated by Asterionella formosa Hass. which abruptly declined after silicon depletion. Spring growth ceased in early June, when Tabellaria flocculosa (Lyngb.) Kütz var. asterionelloides Grun. dominated. Oscillatoria rubescens D.C. and Microcystis aeruginosa Kütz. dominated summer and early autumn followed by the chrysophyte Dinobryon divergens Imh. and D. sociale Ehr. which formed up to 69% of total biovolume in October. Thereafter diatoms and Cryptophyceae (Rhodomonas lacustris Pascher and Ruttner, Cryptomonas pusilla Bach.) became abundant again.Maximum chlorophyll-a concentration in the epilimnion (16 µg 1^–1) was reached during spring growth of the diatoms. During summer higher chlorophyll-a levels were always associated with the metalimnetic layer of Oscillatoria.Compared with earlier studies, both the total biovolume and the share of Oscillatoria rubescens significantly decreased because of reduced nutrient loading of the lake and wash-out of Oscillatoria (theor. renewal time of the lake: 1.7 years).     

Ocean acidification with (de)eutrophication will alter future phytoplankton growth and succession

Human activity causes ocean acidification (OA) though the dissolution of anthropogenically generated CO₂ into seawater, and eutrophication through the addition of inorganic nutrients. Eutrophication increases the phytoplankton biomass that can be supported during a bloom, and the resultant uptake of dissolved inorganic carbon during photosynthesis increases water-column pH (bloom-induced basification). This increased pH can adversely affect plankton growth. With OA, basification commences at a lower pH. Using experimental analyses of the growth of three contrasting phytoplankton under different pH scenarios, coupled with mathematical models describing growth and death as functions of pH and nutrient status, we show how different conditions of pH modify the scope for competitive interactions between phytoplankton species. We then use the models previously configured against experimental data to explore how the commencement of bloom-induced basification at lower pH with OA, and operating against a background of changing patterns in nutrient loads, may modify phytoplankton growth and competition. We conclude that OA and changed nutrient supply into shelf seas with eutrophication or de-eutrophication (the latter owing to pollution control) has clear scope to alter phytoplankton succession, thus affecting future trophic dynamics and impacting both biogeochemical cycling and fisheries.     

Inter-annual,seasonal and spatial variability in nutrient limitation of phytoplankton production in a river impoundment

We characterize seasonal and spatial patterns in phytoplankton abundance, production and nutrient limitation in a mesotrophic river impoundment located in the southeastern United States to assess variation arising from inter-annual differences in watershed inputs. Short-term (48 h) in situ nutrient addition experiments were conducted between May and October at three sites located along the longitudinal axis of the lake. Nutrient limitation was detected in 12 of the 18 experiments conducted over 2 years. Phytoplankton responded to additions of phosphorus alone although highest chlorophyll concentrations were observed in enclosures receiving combined (P and N) additions. Growth responses were greatest at downstream sites and in late summer suggesting that those populations experience more severe nutrient limitation. Interannual variation in nutrient limitation and primary production corresponded to differences in the timing of hydrologic inputs. Above average rainfall and discharge in late-summer (July–October) of 1996 coincided with higher in-lake nutrient concentrations, increased production, and minimal nutrient limitation. During the same period in 1995, discharge was lower, nutrient concentrations were lower, and nutrient limitation of phytoplankton production was more pronounced. Our results suggest that nutrient limitation is common in this river impoundment but that modest inter-annual variability in the timing of hydrologic inputs can substantially influence seasonal and spatial patterns.