Alkaline phosphatase activity and cellular phosphorus as an index of the phosphorus status of phytoplankton in Minnesota lakes

SUMMARY. Total alkaline phosphatase activity is inversely related to cellular phosphorus in the particulate organic matter of waters above and below the thermocline in nine Minnesota lakes. Diagnostic criteria for assessing surplus and limiting levels of phosphorus are proposed. When applied to seasonal changes in phosphorus status in Lake Josephine, they demonstrate severe phosphorus starvation in late summer and autumn.     

东海浮游植物数量分布与优势种

根据1997～2000年东海23°30′～33°N、118°30′～128°E海域4个季节海洋调查资料,运用定量、定性方法,探讨了东海浮游植物总丰度的平面分布、季节分布及变化的动力学机制,同时还探讨了东海浮游植物优势种的生态学特征和对温盐环境适应特征。结果表明:东海浮游植物总丰度有明显的季节分布,秋季总丰度达到4季最高峰,均值为211.91×104cell.m-3,夏季次之(50.40×104cell.m-3),冬季11.34×104cell.m-3,春季(2.01×104cel.lm-3)最低。春夏季东海近海(Ⅰ和Ⅲ)高于外海(Ⅱ和Ⅳ),秋冬季东海北部外海(Ⅱ)高于近海(Ⅰ),南部近海(Ⅲ)高于外海(Ⅳ)。4季共出现优势种(Y≥0.02)11种,冬季的主要优势种为洛氏角毛藻和细弱海链藻,春季的主要优势种为洛氏角毛藻和夜光藻,夏季以拟弯角毛藻和细长翼根管藻为主要优势种,秋季优势种仅为聚生角毛藻。浮游植物的聚集强度指数为较大正值,聚集作用明显。从全年的逐步回归分析结果看,温度是影响浮游植物总丰度季节分布的主要因子,盐度是次要因子。浮游植物的11个优势种之间生存环境适应比较,洛氏角毛藻和中华盒形藻生长温度幅度较大,可以在12～28℃水温增长,因而春、夏和冬季都成为优势种。中肋骨条藻适合生长的水温范围都较小,仅为22～28℃。聚生角毛藻更小,仅21～25℃。洛氏角毛藻和中华盒形藻生长温盐度和高分布区温盐度范围比聚生角毛藻和中肋骨条藻都广,而秋季数量却低于聚生角毛藻。     

Determination of available phosphorus for phytoplankton populations in lakes and rivers of southeastern Norway

A biotest method with diluted phytoplankton populations was used to determine external concentrations of available phosphorus in water samples with high concentrations of inorganic seston from River Rømua. RP (total molybdate reactive P measured on unfiltered samples) was approximately the P fraction available for Synedra cf. acus, Asterionella formosa and Oscillatoria agardhii. In filtered samples RP_F was the available concentration of P.The ratio RP:RP_F may give valuable information on the ratio between total available P (including available P in seston) and available P in filtered water. Different filter types may give different RP: RP_F ratios. The ratio RP:RP_F was often high during spring and autumn in River Rømua and the lakes studied. During the period June–September RP:RP_F 1 in most of the lakes and periodically in River Rømua.     

长湖浮游植物优势种生态位特征及种间联结性分析

为了解生态调控后的浮游植物群落稳定性和优势种种间联结性,于2020年10月—2021年7月按季节对湖北长湖浮游植物群落进行调查。运用生态位宽度、生态位重叠值、方差比率法、卡方检验、Pearson相关性检验和Spearman相关性检验的方法对浮游植物优势种间的相互关系进行综合分析。结果显示：四季共鉴定出浮游植物8门、67属、78种;优势种19种。长湖属于绿藻+蓝藻+硅藻为主的水体。其中,梅尼小环藻(Cyclotella meneghiniana)和四尾栅藻(Scenedesmus quadricauda)为四季共有优势种,对水环境有较好的指示作用,显示长湖水体处于中度富营养化状态。根据优势度和生态位宽度的结果,19个优势种可以划分为4个类群。生态位重叠值的变化范围为0.02—0.96,季节差异明显,秋季>冬季>春季>夏季。方差比率的结果显示秋季和冬季浮游植物优势种间总体呈现显著正联结,群落较稳定;春夏季节优势种间总体呈现不显著负联结,群落处于波动状态。卡方检验、Pearson相关性检验和Spearman相关性检验结果综合显示：优势种对间联结性的显著率较低,群落种间联结不...     

大亚湾大鹏澳水域春季浮游植物优势种的演替

根据2002年4月28日～5月27日大亚湾大鹏澳内每日采样的现场连续观测资料,使用主分量分析方法和多元回归方法,分析浮游植物优势种类之间的关系及影响其生长与演替的主要理化因子,建立春季浮游植物优势种类的演替模型。模型表明,中肋骨条藻和柔弱菱形藻之间为竞争关系;与浮游植物(以硅藻为主)生长密切相关的理化因子为温度(T)、溶解氧饱和度(DOsat)、铵氮(NH4-N)、亚硝酸氮(NO2-N)、磷酸盐(PO4-P)、硅酸盐(SiO3-Si)。影响中肋骨条藻的理化因子还有盐度(S)和氮磷比值(NO3／PO4)。并根据优势种类发生演替期间的环境变化(降雨),分析了浮游植物优势种由中肋骨条藻演替为柔弱菱形藻的过程。     

The impact of climate on the geographical distribution of phytoplankton species in boreal lakes

Here, we use a novel space-by-time approach to study large-scale changes in phytoplankton species distribution in Swedish boreal lakes in response to climate variability. Using phytoplankton samples from 27 lakes, evenly distributed across Sweden, all relatively unimpacted by anthropogenic disturbance and sampled annually between 1996 and 2010, we found significant shifts in the geographical distribution of 18 species. We also found significant changes in the prevalence of 45 species (33 became more common and 12 less common) over the study period. Using species distribution models and phytoplankton samples from 60 lakes sampled at least twice between 1992 and 2010, we evaluated the importance of climate variability and other environmental variables on species distribution. We found that temperature (e.g., extreme events and the duration of the growing season) was the most important predictor for species detections. Many cyanobacteria, chlorophytes, and, to a lesser extent, diatoms and zygnematophytes, showed congruent and positive responses to temperature. In contrast, precipitation explained little variation and was important only for a few taxa (e.g., Staurodesmus spp., Trachelomonas volvocina). At the community level, our results suggest a change in community composition at temperatures over 20 °C and growing seasons longer than 40 days. We conclude that climate is an important driver of the distributional patterns of individual phytoplankton species and may drive changes in community composition in minimally disturbed boreal lakes.     

Comparative limnology,species diversity and biomass relationship of zooplankton and phytoplankton in five freshwater lakes in Kenya

Comparative studies on the limnology, species diversity and standing stock biomass of phytoplankton and zooplankton in five freshwater lakes, Naivasha and Oloidien, Ruiru, Masinga and Nairobi reservoirs, were undertaken. Phytoplankton chlorophyll a, dissolved oxygen and temperature were also measured. Thermocyclops oblongatus (Copepoda) was dominant in all the lakes. Ceriodaphnia cornuta and Diaphanosoma excisum (Cladocera) dominated in lakes Naivasha and Oloiden, whereas in Ruiru, Masinga and Nairobi reservoirs, Brachionus angularis and Hexarthra mira (Rotifera) were the dominant zooplankters. Phytoplankton biomass as chlorophyll a was lowest in Ruiru dam 5.64 ± 4.0 µg l^-1 and highest in the eutrophic Nairobi dam 71.5 ± 12.02 µg l^-1. The endorheic lakes Naivasha and Oloidien showed medium values of 24.5 ± 4.0 µg l^-1.     

The influence of different disturbance frequencies on the species richness,diversity and equitability of phytoplankton in shallow lakes

The relationships between the species richness, diversity and equitability of phytoplankton is discussed in the context of Connell's (1978, Science 199: 1304–1310) Intermediate Disturbance Hypothesis (IDH). The records of 759 vertical phytoplankton samples, which were obtained from four shallow central European lakes (Balaton, Neusiedlersee, and two small artificial ponds) at daily to weekly intervals were analysed.

1. The Shannon-Weaver function was used to measure diversity of the recorded species compositionof the phytoplankton. It is shown on fictitious data that compositional diversity is sensitive to the numberof coequilibrating species provided that the suspected interrelationship between diversity and ‘complexity’is amenable to the application of this method.
2. The disturbance scale that was developed on the basis of the field records fits well to Reynolds'(1988, Verh. int. Ver. Limnol. 23: 683–691) derivation: < 3 days qualifies as high frequency, approximatel3–8 days as intermediate frequency and > 8–9 days as low frequency of disturbance for phytoplankton.
3. Arithmetical means of the compositional diversity of phytoplankton under different frequencies ofdisturbance support the hypothesis that maximal diversity appears at intermediate frequencies.
4. There are different reasons for decrease in diversity at higher and lower frequencies. Inequitabilitydiminishes diversity at low disturbance; while species number decreases at high frequencies.
5. The case of Neusiedlersee calls attention to the fact that it is difficult, if at all possible, to differentiatebetween the indices under continuous stress and high frequency of disturbance in lakes in temperateregions. Similar species number-equitability pattern are induced by both and it is also presumablethat high frequency disturbance can itself effect a serious stress.
6. The striking effects that regular major periodic events (e.g. significant changes in the grazing pressureat the onset of the clear-water phase, autumnal cooling) in the plankton have on its species diversity areevident. Thus, the relative importance of intermediate frequency disturbances has its own seasonality:it is increasingly important in periods (partly in the spring, but mostly in the summer-autumn equilibriumphases), in which competition among phytoplankton species is increasing. This observation suggestsa way by which the stochasticity-based IDH can be incorporated into rather more deterministicexplanations (e.g. PEG-model; Sommer et al., 1986. Archiv für Hydrobiologie 106: 433–471) of planktonsuccession.
7. The most controversial issue and, therefore, the main difficulty, with IDH is that it not onlymaintains species richness in an ecosystem but it also supposes its presence. The lack of either earlyor late successional species in a given community can inactivate the mechanism. From the point of viewof the diversity-species richness relationship, the persistence of disturbance at given frequencies is ofgreater importance than the temporal alterations themselves in the evolutionary ecology of the phytoplankton.
8. For characteristically unperturbed phytoplankton communities (no case was studied here), equilibriumconcepts (niche diversification, etc.) should be more strongly applicable to their diversity andspecies richness.

     

太湖浮游植物优势种长期演化与富营养化进程的关系

利用1991年至2002年每月一次的监测资料,系统分析了浮游植物优势种和生物量的周年变化情况。同时,总氮、总磷和浮游植物叶绿素a含量等相关资料也被用于解释太湖富营养化演化与浮游植物的关系。结果显示,太湖总氮、总磷、叶绿素a和生物量均呈自梅梁湾底至湖心的逐步递减趋势。在20世纪80年代末太湖刚开始富营养化时,浮游植物优势种群从硅藻转变为蓝藻。之后,浮游植物优势种群一直是蓝藻,但各年的浮游植物总生物量有变化。总氮、总磷、叶绿素a和生物量的年均值持续增长至1996年,其后有逐步下降的趋势,究其原因可能和当地政府在太湖流域的控制排污行动有关。微囊藻在太湖的占优是太湖富营养化的标志之一。研究结果说明浮游植物在大型浅水湖泊中可以作为反映富营养化进程的生态指标。     

Spatial predictors of fish species composition in European lowland lakes

Composition of animal communities can be shaped by both local and regional processes. Among others, dispersal of organisms links local and regional patterns and determines the similarity of communities at increasing spatial distances. Unique and shared spatial and environmental contributions to fish community composition were calculated for watercourse distances between 49 hydrologically connected lakes in the German lowland area. Variation partitioning indicated a dominant unique effect of spatial predictors on fish community composition, whereas the effects of lake morphometry and productivity were weaker. The spatial effect was attributable to an uneven occurrence of small, littoral fish species found even at the small spatial extension covered here (maximum spatial distance ?550 km). Distance decay of community similarity was moderate, but significant, if all 31 fish species were considered, but the slope of the decay function became steeper if only 11 small‐sized, primarily littoral species were included. These results suggest that fish in European lowland lakes can be considered a metacommunity with limited dispersal along watercourse connections in particular for small‐sized species. The analysis supports that for an appropriate evaluation of spatial effects on fish community similarity, reliable estimates of local richness are required which include in particular also rare, small‐sized species occurring primarily in littoral areas. Furthermore, watercourse distance is a more reliable approximation than Euclidean distance to the real spatial dimension of fish dispersal.     

Year-to-year variation in the occurrence of some dominant phytoplankton species in Dutch coastal waters, 1973–1984

The surface water layer of a 70 km wide area along the Dutch coast has been sampled monthly from (February) 1973 to (August) 1984, as part of a water quality assessment research. The blooming periods of phytoplankton algae studied, fluctuated from year-to-year, but diatom blooms increased in length in the late 1970s. Dinoflagellates decreased in cell numbers in the same period. The observation of highest cell numbers of some diatoms and dinoflagellates in the lower salinity near coastal waters can be explained by eutrophication effects.     

Phosphorus decrease and climate variability: mediators of synchrony in phytoplankton changes among European peri-alpine lakes

1. In an attempt to discern long‐term regional patterns in phytoplankton community composition we analysed data from five deep peri‐alpine lake basins that have been included in long‐term monitoring programmes since the beginning of the 1970s. Local management measures have led to synchronous declines in phosphorus concentrations by more than 50% in all four lakes. Their trophic state now ranges from mesotrophic to oligotrophic. 2. No coherence in phytoplankton biomass was observed among lakes, or any significant decrease in response to phosphorus (P)‐reduction (oligotrophication), except in Lakes Constance and Walen. 3. Multivariate analyses identified long‐term changes in phytoplankton composition, which occurred coherently in all lakes despite the differing absolute phosphorus concentrations. 4. In all lakes, the phytoplankton species benefiting from oligotrophication included mixotrophic species and/or species indicative of oligo‐mesotrophic conditions. 5. A major change in community composition occurred in all lakes at the end of the 1980s. During this period there was also a major shift in climatic conditions during winter and early spring, suggesting an impact of climatic factors. 6. Our results provide evidence that synchronous long‐term changes in geographically separated phytoplankton communities may occur even when overall biomass changes are not synchronous.     

Trophic structure, species richness and biodiversity in Danish lakes: changes along a phosphorus gradient

1. Using data from 71, mainly shallow (an average mean depth of 3 m), Danish lakes with contrasting total phosphorus concentrations (summer mean 0.02–1.0 mg P L?l), we describe how species richness, biodiversity and trophic structure change along a total phosphorus (TP) gradient divided into five TP classes (class 1–5: <0.05, 0.05–0.1, 0.1–0.2, 0.2–0.4,> 0.4 mg P L?1).
2. With increasing TP, a significant decline was observed in the species richness of zooplankton and submerged macrophytes, while for fish, phytoplankton and floating‐leaved macrophytes, species richness was unimodally related to TP, all peaking at 0.1–0.4 mg P L?1. The Shannon–Wiener and the Hurlbert probability of inter‐specific encounter (PIE) diversity indices showed significant unimodal relationships to TP for zooplankton, phytoplankton and fish. Mean depth also contributed positively to the relationship for rotifers, phytoplankton and fish.
3. At low nutrient concentrations, piscivorous fish (particularly perch, Perca fluviatilis) were abundant and the biomass ratio of piscivores to plankti‐benthivorous cyprinids was high and the density of cyprinids low. Concurrently, the zooplankton was dominated by large‐bodied forms and the biomass ratio of zooplankton to phytoplankton and the calculated grazing pressure on phytoplankton were high. Phytoplankton biomass was low and submerged macrophyte abundance high.
4. With increasing TP, a major shift occurred in trophic structure. Catches of cyprinids in multiple mesh size gill nets increased 10‐fold from class 1 to class 5 and the weight ratio of piscivores to planktivores decreased from 0.6 in class 1 to 0.10–0.15 in classes 3–5. In addition, the mean body weight of dominant cyprinids (roach, Rutilus rutilus, and bream, Abramis brama) decreased two–threefold. Simultaneously, small cladocerans gradually became more important, and among copepods, a shift occurred from calanoid to cyclopoids. Mean body weight of cladocerans decreased from 5.1 μg in class 1 to 1.5 μg in class 5, and the biomass ratio of zooplankton to phytoplankton from 0.46 in class 1 to 0.08–0.15 in classes 3–5. Conversely, phytoplankton biomass and chlorophyll a increased 15‐fold from class 1 to 5 and submerged macrophytes disappeared from most lakes.
5. The suggestion that fish have a significant structuring role in eutrophic lakes is supported by data from three lakes in which major changes in the abundance of planktivorous fish occurred following fish kill or fish manipulation. In these lakes, studied for 8 years, a reduction in planktivores resulted in a major increase in cladoceran mean size and in the biomass ratio of zooplankton to phytoplankton, while chlorophyll a declined substantially. In comparison, no significant changes were observed in 33 ‘control’ lakes studied during the same period.     

Ecological status assessment of European lakes: a comparison of metrics for phytoplankton, macrophytes, benthic invertebrates and fish

Data on phytoplankton, macrophytes, benthic invertebrates and fish from more than 2000 lakes in 22 European countries were used to develop and test metrics for assessing the ecological status of European lakes as required by the Water Framework Directive. The strongest and most sensitive of the 11 metrics responding to eutrophication pressure were phytoplankton chlorophyll a, a taxonomic composition trophic index and a functional traits index, the macrophyte intercalibration taxonomic composition metric and a Nordic lake fish index. Intermediate response was found for a cyanobacterial bloom intensity index (Cyano), the Ellenberg macrophyte index and a multimetric index for benthic invertebrates. The latter also responded to hydromorphological pressure. The metrics provide information on primary and secondary impacts of eutrophication in the pelagic and the littoral zone of lakes. Several of these metrics were used as common metrics in the intercalibration of national assessment systems or have been incorporated directly into the national systems. New biological metrics have been developed to assess hydromorphological pressures, based on aquatic macrophyte responses to water level fluctuations, and on macroinvertebrate responses to morphological modifications of lake shorelines. These metrics thus enable the quantification of biological impacts of hydromorphological pressures in lakes.     

Sediment phosphorus release in phytoplankton dominated versus macrophyte dominated shallow lakes: importance of oxygen conditions

Increased discharges of organic matter from different sources in Morales Stream, one of the main tributaries of the Matanza-Riachuelo River, caused not only an increase in its primary production but also drastic changes in the composition of its sediments, thus favoring eutrophication processes. An in situ study was carried out in order to assess the effects of an organic point source contamination (from intensive cattle rearing) on the sediments of Morales Stream. Surface water and sediment samples were analysed to determine the chemical characteristics of the water–sediment system. The amounts and forms of sediment phosphorus were determined using the `EDTA method' (Golterman, 1996) at two sites of the stream having different nutrient loads. The increase in the organic load of Morales Stream waters influences the dynamics of sediment P, producing two main effects: (1) an increase in the organic matter amount of the sediment that leads to an increase in the amount of P associated to organic fractions, which may be released by bacterial activity under anoxic conditions; and (2) a decrease in the concentration of P in the fraction bound to iron. Morales Stream sediments may act as a potential source of P, which can release this nutrient to water under the reducing conditions originated by uncontrolled discharges of organic residues to this water body.     

Spatial, seasonal and long-term variability of phytoplankton photosynthesis in lakes

A cross-system, worldwide approach has been used to ascertainthe spatial, seasonal and long-term variability of areal phytoplanktonphotosynthesis (PP) in lakes using published data sets. Also,the average fraction of annual PP occurring under ice is calculated.The lakes considered embrace a range of properties (depth, mixing,flushing rate, latitude and trophic status). The overall yearlyPP distribution is skewed to the left, suggesting the dominanceof low PP rates in the data set. When comparing lake types,no differences in average PP have been found among them. Inparticular, there are no clear areal PP differences among lakesof different trophic status on yearly, averaged basis, suggestingthat environmental limitations to PP also exist in lakes ofhigher trophic status. Volumetric-based PP can be better usedto outline PP-based trophic differences, but some degree ofoverlap is also apparent. Across all lake types (except in tropicallakes), the PP seasonal course experiences only one peak inthe year, but its timing is clearly different for each laketype. The seasonal variability of PP is lower in tropical lakes,as previously reported, but the variability of the other laketypes is roughly the same. Therefore, the effects of depth,mixing regime, flushing rate and nutrient status on PP seasonalityare difficult to ascertain since they appear to be counterbalancedby other more pervasive, local effects. Particularly, thereis no increase in temporal variability with the trophic statusof lakes, suggesting that PP seasonal control by physical variablesoverrides that of nutrients. Also, no significant relationshipbetween average PP and latitude has been found. Seasonal variabilityincreases as the yearly PP increases. On a relative basis, thereis a spatial gradient of seasonal variability of PP, which isweaker when seasonal variability of PP is considered in interyearcomparisons. Long-term (i.e. interannual) variability of PPis clearly related to increasing yearly averaged PP. Specifically,in temperate, stratifying lakes the seasonal time course ofPP is clearly different from that of phytoplankton biomass,suggesting an uncoupling of both variables as a result of differingP_max and losses throughout the year. On an average basis, environmentalvariables are poor predictors of areal daily PP, thereby implyingthat the interplay of factors is complex and changing throughoutthe year. PP under ice averages 10% of yearly PP, but its variabilityis high enough to make its measurement advisable.     

鄱阳湖湿地优势植物叶片-凋落物-土壤碳氮磷化学计量特征

2013年11月初在鄱阳湖南矶湿地国家级自然保护区,采集芦苇(Phragmites australis)、南荻(Triarrhena lutarioriparia)、菰(Zizania latifolia(Griseb.))、灰化苔草(Carex cinerascens)、红穗苔草(Carex argyi)和水蓼(Polygonum hydropiper)等6种优势植物新鲜叶片、凋落物及表层0—15cm土壤样品测定了碳(C)、氮(N)、磷(P)含量,以阐明不同物种、不同生活型间C、N、P化学计量差异,探讨化学计量垂直分异。结果表明:1)C、N、P含量变化范围分别为:叶片380.6—432.2 mg/g,15.3—32.6 mg/g和1.3—2.0 mg/g;凋落物345.4—416.1 mg/g,10.8—20.8 mg/g和1.1—1.7 mg/g;土壤15.0—38.1 mg/g,1.2—3.1 mg/g和0.7—1.1mg/g,不同物种间叶片、凋落物及土壤C、N、P含量差异显著,且叶片C、N、P含量显著高于凋落物与土壤。2)土壤C∶N、C∶P及N∶P值显著低于叶片与凋落物,且土壤C、N、P化学计量关系与凋落物更为密切,凋落物的C∶N、N∶P分别能解释土壤C∶N、N∶P变异的35%、18%。3)挺水植物与湿生植物之间叶片C∶N、N∶P值差异显著,C∶P则差异不显著,凋落物C∶N、C∶P与N∶P均未达到显著性差异。     

Differential sensitivity to natural ultraviolet radiation among phytoplankton species in Arctic lakes (Spitsbergen,Norway)

Incubation experiments demonstrated a differential sensitivity to natural UV-radiation among the dominant phytoplankton species from three Arctic lakes, situated near Ny-Ålesund, Spitsbergen (79° N). The growth of small chlorophytes, diatoms and picocyanobacteria from two oligotrophic lakes was inhibited primarily by the shorter wavelength UV components, while the growth of the larger colony-forming species (cyanobacteria, Planktothrix sp., Woronichinia sp. and the chrysophyte, Uroglena americana Calkins) apparently was stimulated. These colonies (not easily eaten by daphnids) dominated at the end of the experiment in those treatments where the short wavelength UV components were not excluded. For the two oligotrophic localities, 70 and 61%, respectively, of total phytoplankton biovolume were edible in the treatments excluding short wavelength UV, compared to only 13 and 19%, respectively, in the treatments including such radiation. For the third, more productive and less transparent lake, the percentage of edible species in the treatments with and without short wavelength UV radiation did not differ (ca. 75% for both treatments).     

淮北相山恢复演替群落优势树种的水分生理生态研究

对淮北相山不同恢复演替阶段植被中4个优势树种叶片的水分生理指标进行研究,结果表明：在同一生境(混交林)下,广布优势种（酸枣和牡荆）比局部优势种（柘树和构树）具有更强的耐旱性,但后者的资源获取能力更强,生长速度更快;酸枣和牡荆的耐旱机理不同,酸枣为低水势耐旱植物;牡荆为高水势耐旱植物。酸枣和牡荆的叶片水分生理指标均随群落环境的不同而表现出一定表型可塑性,它们在不同群落中的耐旱性依次为：混交林林内>混交林林缘>灌丛>灌草丛>人工侧柏林。生理可塑性导致酸枣和牡荆具有更宽的生态幅和更强的耐旱性,这是它们在相山成为广布优势种的重要原因。