白鱼泡湿地春季硅藻植物初报

对2014年春季白鱼泡湿地内的硅藻植物群落组成进行初步研究,共发现硅藻门植物69个分类单位,分别隶属于2纲6目10科24个属,初步分析了白鱼泡湿地春季硅藻植物群落的组成,大部分硅藻为普生种类,同时出现了一些嗜碱种类,如:Navicula radiosa(Kützing)、Rhopalodia gibba(Müll)等,还有一些嗜酸和寡盐的种类出现。     

Community analysis in stream biomonitoring: what we measure and what we don't

Diatom assemblages from 83 epilithic samples taken from the Mesta River, Bulgaria, were regressed against three sets of predictor variables, i.e. environmental, spatial, and temporal. Redundancy analysis (RDA) of species and environmental data explained 36% of the diatom variance and extracted several important gradients of species distribution, associated with a downstream increase in nutrient levels, pH, temperature, and organic pollution. The inclusion of spatial and temporal variables in the RDA model captured additional 24% of the diatom variance and revealed three more gradients, a spatial gradient represented by higher order polynomial terms of latitude and longitude, and two temporal gradients of annual and seasonal variation. Partial RDAs demonstrated that the unique contribution of each predictor set to the explained diatom variance was the highest in the spatial dataset (16%), followed by the environmental (9%), and the temporal (7%) datasets. The remaining 28% of the variance was explained by the covariance of the predictor sets. This suggests that in biomonitoring of single stream basins, the cheap and simple account of space and time would explain most of the variance in assemblage composition obviating the necessity of expensive and time-consuming environmental assessments. The nature of the underlying environmental mechanisms can be easily inferred from the diatom composition itself.     

Changes in the cell size of the diatom Cylindrotheca closterium in a hyperhaline pond

Cell length of the diatom Cylindrotheca closterium (Ehr.) Reimann & Lewin was investigated on a fortnightly basis from January to April 2000 in a hyperhaline pond (Sardinia, Mediterranean Sea) and relationships, with changes in temperature, salinity, and nitrite concentrations were assessed using single and multiple regression analyses. Results of our study indicate that C. closterium cell size was inversely related to temperature changes, but that salinity and nitrite concentrations may have a major idiosyncratic effect on cell size variability.     

Changes in the cell size of the diatom Cylindrotheca closterium in a hyperhaline pond

Cell length of the diatom Cylindrotheca closterium (Ehr.) Reimann & Lewin was investigated on a fortnightly basis from January to April 2000 in a hyperhaline pond (Sardinia, Mediterranean Sea) and relationships, with changes in temperature, salinity, and nitrite concentrations were assessed using single and multiple regression analyses. Results of our study indicate that C. closterium cell size was inversely related to temperature changes, but that salinity and nitrite concentrations may have a major idiosyncratic effect on cell size variability.     

Accumulation of Am by suspended matter, diatoms and aquatic weeds of the Yenisei River

In this work we experimentally estimated the capacities of the key components of the Yenisei River (Russia): particulate suspended matter (seston), diatom microalgae, and submerged macrophytes for accumulating ²⁴¹Am from water. In our experiments large particles of seston (>8 μm), comparable in size with diatoms, took up most of americium from water. The accumulation of americium by isolated diatom algae (Asterionella formosa and Diatoma vulgare) was lower than by total seston. The concentration factors (CFs) of ²⁴¹Am for seston of the Yenisei River in our experiments were (2.8-6.9)·10⁵; for diatoms - (1.5-4.2)·10⁴. The CFs for aquatic plant Elodea canadensis were within the same order of magnitude as those for diatoms. Activity concentration and CFs of ²⁴¹Am were nearly the same in experiments under dark and light conditions. This is indicative of an energy independent mechanism of americium uptake from the water by diatoms and submerged macrophytes.     

N:P stoichiometry and transparent exopolymeric particles buffer ecological impacts of nutrients in the Ganga River: a mesocosm study

We investigated the possible drivers of the N:P stoichiometric shift and its relationship with micro-algal production of transparent exopolymeric particles (TEP) along a 35?km gradient of the Ganga River. The objective was to evaluate if the trade-off between N:P stoichiometry and production of TEP helps in maintaining water quality of the river. Mesocosm experiments were conducted to examine N:P-TEP linkages and its role in turbidity removal. In situ measurements did not show Si to be a limiting nutrient (N:Si?Aulacosira granulata and Fragilaria intermedia. Settling efficiency, turbidity removal and sedimentation of TEP, biogenic silica (BSi) and biomass all increased with decreasing N:P ratio proportionately to the amount of TEP produced in the mesocosm. The study demonstrates that trade-off between N:P stoichiometry and the production of TEP generates feedback to buffer the ecological impacts of nutrient pollution.     

Integrating geochemical (surface waters, stream sediments) and biological (diatoms) approaches to assess AMD environmental impact in a pyritic mining area: Aljustrel (Alentejo, Portugal)

Aljustrel mines were classified as having high environmental hazard due to their large tailings volume and high metal concentrations in waters and sediments.To assess acid mine drainage impacted systems whose environmental conditions change quickly,the use of biological indicators with short generation time such as diatoms is advantageous.This study combined geochemical and diatom data,whose results were highlighted in 3 groups:Group 1,with low p H(1.9–5.1)and high metal/metalloid(Al,As,Cd,Co,Cu,Fe,Mn,Ni,Pb,Zn;0.65–1032 mg/L)and SO_4(405–39124 mg/L)concentrations.An acidophilic species,Pinnularia aljustrelica,was perfectly adapted to the adverse conditions;in contrast,teratological forms of Eunotia exigua were found,showing that metal toxicity affected this species.The low availability of metals/metalloids in sediments of this group indicates that metals/metalloids of the exchangeable fractions had been solubilized,which in fact enables metal/metalloid diatom uptake and consequently the occurrence of teratologies;Group 2,with sites of near neutral p H(5.0–6.8)and intermediate metal/metalloid(0.002–6 mg/L)and SO_4(302–2179 mg/L)concentrations;this enabled the existence of typical species of uncontaminated streams(Brachysira neglectissima,Achnanthidium minutissimum);Group 3,with samples from unimpacted sites,showing low metal/metalloid(0–0.8 mg/L)and SO_4(10–315 mg/L)concentrations,high pH(7.0–8.4)and Cl contents(10–2119 mg/L)and the presence of brackish to marine species(Entomoneis paludosa).For similar conditions of acidity,differences in diversity,abundance and teratologies of diatoms can be explained by the levels of metals/metalloids.     

Which group is best? Attributes of different biological assemblages used in freshwater biomonitoring programs

Of the many groups of organisms proposed for use in biomonitoring, assemblages of fish, algae, and benthic macroinvertebrates are the most commonly selected. Purported advantages and disadvantages of using these groups, along with those of zooplankton, were assembled from 65 different publications and websites. From these, 13 categories of advantages and nine of disadvantages were created. The diversity of the assemblage and its importance to the ecosystem were reported as advantages in >20% of citations for each group; these similarities suggest that some redundancy exists among the different groups in terms of these features. Likewise, sampling difficulties and lack of analytic metrics were disadvantages listed in >20% of citations for each group. Few reported advantages (e.g. recreational value of fish) or disadvantages (e.g. short generation time of algae) were unique for a particular assemblage. The validity of reported advantages and disadvantages were sometimes region specific, other times incorrect. The choice of which assemblage is most appropriate for a biomonitoring program ultimately depends on the characteristics of the area to be studied and the program objectives.     

Combination of two indication systems in pre-alpine lakes — diatom index and macrophyte index

Since the climax of eutrophication in the early 1980s mainly greater lakes have been investigated and monitored in terms of their nutrient charge. In the future there will still be a need to develop guidelines for monitoring the trophic status of smaller lakes. Four small lakes were investigated by the author in the years 1996 and 1997. In order to define the nutrient charge of those lakes more precisely, special emphasis has been put upon the two criteria diatoms and macrophytes. Eventually an evaluation of the lakes' catchment areas will also be an important component of these studies. Benthic diatoms are the main part of periphyton. As unicellular fast reproducing organisms they are excellent indicators for trophic situations in lakes. The diatom index denotes the trophic status of the littoral zone during the last few weeks before sampling. The macrophytes, however, reflect the nutrient charge over a longer period, i.e. several years. The macrophyte index is based on the fact that some species are most prevalent at certain nutrient loads. The effort to combine these two indication systems carries a high resolution of spatial nutrient changes as well as in temporally changes.     

Sediment-based investigation of naturally or historically eutrophic lakes -- implications for lake management

Implementation of the EU Water Framework Directive will call for new lake monitoring and management strategies. Therefore, different methods need to be tested in order to achieve reliable assessment of lake background conditions and water quality. Sediment-based techniques provide one such tool for lake management. In this work, 10 lakes, presumed to be naturally eutrophic, were investigated with a paleolimnological short core study. The aim of the study was to examine the composition of the diatom assemblages in their natural state, estimate their change over time and assess the background nutrient levels. One sediment profile from each lake was divided into six sub-samples that were analyzed for diatoms (60 samples). Diatom-based inference models were applied to reconstruct the past total phosphorus concentration and assess the eutrophication. The results indicated that all the lakes studied had already been nutrient-rich before the impact of modern agriculture. However, diatom assemblages have changed remarkably over time and total phosphorus concentrations have generally increased, so at present only two of the study lakes are close to their natural status. This suggests that naturally eutrophic lakes will probably require management actions to fulfill the new directive requirements in the future.