Planktonic Algae Research Articles

Combating planktonic algae with benthic algae

Anthropogenic eutrophication of surface waters may cause mass development of algae, including cyanoprokaryotes, with serious effects on ecosystem health. In the current study, drastic hydrological changes initiated a eutrophication process of a former backwater of the river Danube (Austria). As a first restoration measure, a gravel filter followed by a phosphate trap was installed in 2007. Because this purification system was not effective enough, we constructed an additional biological treatment in 2011, using the self-purification process in streams, particularly through photoautotrophic biofilms. We installed artificial stream beds (algae turf scrubber=ATS) at the gravel filter surface, which were supplied with water from the backwater. The study aimed to estimate growth, productivity and composition of the algal biomass to test the potential of ATSs for nutrient removal and to examine the biomass with regard to further applications. Measurements of biomass, nutrients and fatty acids were done during three runs. Maximal phosphorus removal rates were observed with about 19mg total phosphorus m−2d−1; peak biomass of approximately 250gm−2 dry mass was achieved. In total, approximately 18.8kg of phosphorusha−1 could be removed within five months. Further use of the harvested biomass as fertilizer, fermentation feedstock or combustion fuel is possible. The pilot study showed that the ATS technology has great potential and provides an effective and ecologically sustainable way to remove nutrients from surface waters, with the positive effect of producing biomass.

Suspended organic particles drive the development of attached algal communities in degraded peatlands

Mineral particles in rivers have been shown to cover adnate algal species, promoting motile and filamentous species. Such effects and the role of detrital particles have not been studied in stagnant waters. In degraded peat lands, detrital particles are very prominent and therefore we studied the interaction of organic particles and attached algae. Field grown communities were translocated to microcosms and exposed to organic particles in the laboratory. Colonization of substrate was also studied in field enclosures that allowed settlement of particles. We compared algal settlement under low particle regime (enclosures) with settlement at high particle concentrations (outside). Suspended particles were found to be trapped by attached algae in proportion to the concentration of particles. The presence of particles in the incubations and field enclosures modified species composition, reducing the share of low-profile forms. These experimental results were verified in a field survey with a wide range of turbidity. The share of low-profile species was lowest in turbid ditches while motile and planktonic algae dominated, in agreement with the results from experiments. It is argued that the strong interactions of attached algae and suspended organic matter found in peat land ditches is a characteristic feature of detritus rich waters.

Interstadial inland dune slacks in south-west Slovakia: a multi-proxy vegetation and landscape reconstruction

Palaeoecological studies spanning back to the Bølling/Allerød (GI-1) Interstadial of the Late Glacial in the whole Western Carpathians and adjacent lowlands are extremely scarce. To improve our knowledge about the landscape structure and diversity of wetland habitats, we analysed two palaeoecological interstadial sequences of pollen and macrofossils (bryophytes, vascular plants and molluscs) from the sandy landscape of the Borská lowland (southwest Slovakia). The deposits differed between the two sequences analysed, consisting predominantly of lacustrine chalk or brown-moss sedge fen peat, respectively. The results showed that, during wetter and warmer conditions during the Interstadial, open large dunes had been stabilised by pine woodlands admixed by birch. Contrary to the Podunajská lowland, which is situated eastwards towards the centre of the Pannonian Plain, broadleaf thermophilous trees such as Ulmus, Quercus and Tilia were almost absent in the study region, which suggests an importance of the bedrock for Late-Glacial forest vegetation. Salix, Alnus and Betula nana scrubs were probably scattered across wetlands. Active dunes were occupied by Hippophaë rhamnoides and steppe vegetation with grasses, Artemisia and Helianthemum. Low abundance of Chenopodiaceae pollen suggests that the sandy bedrock was probably unfavourable for the development of salt-rich habitats. Wetland habitats were diverse and abundant in the inter-dune space, partly resembling recent coastal dune slack vegetation or alluvial salty grasslands in continental central Asia. The wetland habitats comprised aquatic habitats with Myriophyllum, Potamogeton filiformis, P. pectinatus, P. pussilus, Sparganium minimum and planktonic algae (Pediastrum and Botryococcus), strongly continental calcareous-fens with Blysmus rufus and Triglochin maritima, boreocontinental brown-moss sedge fen fens with Drepanocladus trifarius, Carex lasiocarpa, Menyanthes trifoliata and Scorpidium scorpioides) and reed beds with Cicuta virosa, Phragmites and Schoenoplectus tabernaemontani. Remains of these unique wetland mosaics have recently disappeared because of human activities including peat extraction and dune stabilisation by pine plantations, which have transformed the modern landscape.

The palynology of late Miocene sinkhole deposits from Upper Silesia, Poland

This paper presents the results of a palynological investigation of an assemblage of pollen, spores and organic-walled microalgal remains from the paleosinkhole infill exposed at Górażdże, Upper Silesia, SW Poland. The results of previous palynological studies indicate that the infill was deposited in the late Miocene, probably during the more humid Tortonian stage.The sinkhole at Górażdże was filled with shallow water that periodically might have dried out or, at least, undergone seasonal warming. Green algae (Chlorophyta) such as Zygnemataceae, Botryococcus and Pediastrum, as well as Sigmopollis were major components of the algal community. The presence of planktonic algae Pediastrum and Tetraedron as well as pollen grains of aquatic plants, such as Nuphar and Nymphaea, indicate that there were extended periods of standing water. The pond was surrounded by vegetation composed of herbs and riparian forests dominated by Alnus, Salix, Ulmus, Pterocarya, Carya, and others. More dry terrains were presumably covered by mixed forests composed of Pinus, Tsuga, Picea, Quercus, Carpinus, Fagus, Betula, and others, with only a small admixture of thermophilous plants, such as Castanea. Ericaceae were presumably a component of the groundcover of the forests, or they formed their own open dwarf-shrub communities, such as bush swamps or heathlands. A high frequency of Poaceae pollen grains might reflect the development of open landscapes. The climate during the deposition of sediments in the sinkhole was warm temperate and mild, without severe winters.A comparison of the sporomorph association from the studied sinkhole with another Neogene paleosinkhole palynoflora from the neighboring Tarnów Opolski site revealed asynchronous karst development in the western part of the Upper Silesian Upland, with the infill sediments being at least middle and late Miocene in age.

Temporary ice microalgae community in Taganrog Bay of the Azov Sea

The temporary ice algae community in the mixing zone of brackish and fresh waters of the Taganrog Bay of the Azov Sea is described. A high abundance and biomass of planktonic algae and a high chlorophyll a concentration have been registered in samples of under-ice water taken on February 2013. The mass development of the diatom Stephanodiscus hantzschii Grunow blooming on the ice in the eastern part of Taganrog Bay is described for the first time. The quantitative data on the under-ice microalgae community and the related hydrochemistry are published. The obtained results could be used in total productivity estimates in the Azov Sea.

Novel tetracyclic terpanes in crude oils and source rock extracts in pearl river mouth basin and their geological significance

Novel tetracyclic terpanes X and Y namely C24-des-A-oleanane and C27 tetracyclic terpane were detected in crude oils and source rock extracts in Zhu 1 depression in Pearl River Mouth Basin by GC-MS analysis technology. These compounds are similar to oleanane in the structure, and their relative abundance in m/z 191 partial mass chromatogram has a good correlation with oleanane. Here compounds X and Y are considered to be derived from the des-A degradation of oleanoid precursor. The ratio of X/(X+C24) and Y/(Y+C24) increase with the increasing inputs of terrigenous organic matter in crude oils. Wenchang Formation middle-deep lacustrine source rocks with planktonic algae organic matter inputs and oil generating from it contain low abundance of compounds X and Y, while Enping Formation coal measures source rocks with terrigenous higher plants organic matter inputs and oil generating from it usually have higher compounds X and Y. In general when two terrigenous compounds C19 tricyclic terpane and bicadinane-T are high in crude oils, there are also a corresponding high abundant compounds X and Y. Relative abundance of compounds X and Y is closely related to the source of organic matter and it can indicate the input of terrigenous organic matter.

Ecological engineering restoration of a non-point source polluted river in Northern China

River restoration is the re-establishment of a river to a state that is more reflective of its predisturbance form. To restore a river polluted by human interference, we conducted an ecological restoration study from 2009 to 2011 on parts of the Yitong River, which is a typical non-point source polluted river in Northern China. The engineering included three parts: riparian vegetation buffering strip (part 1); multi-functional ecological fishponds (part 2), and river channel enhancement zone (part 3). By monitoring and evaluating the pollution indices of the study area's inlet and outlet, we found that the ecological engineering could significantly enhance the reduction rate of NH3-N, COD, and BOD5, which had increased from −14.29%, 1.81%, and −0.5% before restoration to 66.29%, 10.81%, and 7.25% in 2011 (post-restoration), respectively. The diversity of planktonic algae became rich, and in particular the species number representing clean water increased from 1 before restoration (2009) to 8 after the restoration (2011). Our results indicate that ecological engineering can significantly reduce non-point source pollution and improve the water quality, biodiversity, and economic benefits, and it is therefore an effective scientific approach for restoring the integrity of the river ecosystem and achieving continuous social and economic development.

Depositional Controls On Mudstone Lithofacies In A Basinal Setting: Implications for the Delivery of Sedimentary Organic Matter

Deep-water mudstones from ancient epicontinental settings are significant repositories for organic matter, but the detailed temporal variations of, and controls on, the abundance and type of organic matter (OM) is little studied. Using micro-petrographic and geochemical data from late Mississippian mudstones of the Widmerpool Gulf, UK, the processes that delivered fine-grained sediment to this basin during a glacioeustatic sea-level cycle are interpreted from detailed lithofacies analysis. Seven primary lithofacies are identified from core, which show specific and systematic variations in total organic carbon (TOC) content and bulk carbon isotope composition of organic material (δ13Corg). During sea-level highstands, thin-bedded carbonate-bearing mudstones are the dominant facies deposited, contain up to 6.6% TOC (average 4.6 ± 1.3%), and have mean δ13Corg of −28.5 ± 0.9‰. During phases of lower sea level, thin-bedded silt-bearing clay-rich mudstones with up to 4.1% TOC (average 2.3 ± 0.8%; mean δ13Corg: −28.2 ± 1.0‰) were interbedded with more organic-lean graded silt-bearing mudstones and sand-bearing silt-rich mudstones (average TOC: 1.7 ± 0.6%) derived from turbidity currents. The latter (mean δ13Corg: −26.2 ± 0.7‰) are closely linked to significant proportions of terrestrial plant material, while some rare plant debris- and sand-bearing mudstones produced from debris flows have more than 7.0% TOC and δ13Corg ≥ −26.0‰. The δ13C values of wood fragments ranged from −27.1‰ to −24.0‰ and therefore the δ13Corg is interpreted as a function of the ratio of marine and terrestrial organic matter. More negative values in the carbonate-bearing and the clay-rich mudstones indicate marine planktonic algae whereas the least negative values reflect greater contribution of terrestrial plant material. The data suggest that the marine conditions prevailed and supported marine planktonic algae throughout different sea-level stages. Marine OM was delivered to the sea floor by continuous hemipelagic settling whereas terrestrial OM was delivered by sediment density flows. Variations in bioproductivity and dilution by siliciclastics influenced the burial rate of marine OM. Organic-rich mudstones preserved in these marine basins are potential hydrocarbon source rocks, especially as unconventional (shale gas) reservoirs. Detailed microtextural and compositional analysis coupled with rigorous geochemical parameters as used in this study are important for the understanding of the source-rock potential of basinal mudstones, and of fine-grained organic-rich sediments in general.

Diel vertical distribution of planktonic microcrustaceans (Crustacea: Cladocera, Copepoda) in a natural shallow lake from Transylvania, Romania

The diel vertical migration (DVM) of planktonic cladocerans and copepods was investigated in Lake Stiucii, a natural shallow lake from north-western Romania. The aim of this study was to test the existence of migration patterns for cladocerans, adult copepods and copepod development stages (copepodites and nauplii) in four sampling seasons: October 2004; January, April and July 2005. The main abiotic and biotic factors influencing the microcrustacean day and night distributions were also analyzed: water temperature, dissolved oxygen, transparency; the distribution of planktonic algae at midday and at midnight in July and the number of larvae of the dipteran predator Chaoborus present in the plankton samples. For most microcrustaceans, nighttime biomass exceeded the daylight values in the water column, indicating a strategy of predator avoidance by staying near to the bottom of the lake during the day. Normal DVM patterns (up at night and down during the day) were observed for cladocerans and adult copepods, while for copepodites and nauplii no clear patterns were depicted. Negative correlations between daytime vertical profiles of planktonic algae and microcrustacean biomass revealed that both cladocerans and copepods migrated away from phytoplankton-rich waters during the day, to escape visual predators like fish. The return in the water column during the night was influenced by invertebrate predation pressure, exerted by Chaoborus larvae.

Drinking water quality and hospital admissions of elderly people for gastrointestinal illness in Eastern Massachusetts, 1998–2008

We used a Poisson regression to compare daily hospital admissions of elderly people for acute gastrointestinal illness in Boston against daily variations in drinking water quality over an 11-year period, controlling for weather, seasonality and time trends. The Massachusetts Water Resources Authority (MWRA), which provides non-filtered water to 1.5 million people in the greater Boston area, changed its disinfection method from chlorination to ozonation during the study period so we were also able to evaluate changes in risk associated with the change in disinfection method. Other available water quality data from the MWRA included turbidity, fecal coliforms, UV-absorbance, and planktonic algae and cyanobacteriae concentrations. Daily weather, rainfall data and water temperature were also available. Low water temperature, increases in turbidity and, to a lesser extent, in fecal coliform and cyanobacteriae were associated with a higher risk of hospital admissions, while the shift from chlorination to ozonation has possibly reduced the health risk.The MWRA complied with US drinking water regulations throughout the study period.

Gas transfer velocities of methane and carbon dioxide in a subtropical shallow pond

Two diel field campaigns under different weather patterns were carried out in the summer and autumn of 2013 to measure CO2 and CH4 fluxes and to probe the rates of gas exchange across the air–water interface in a subtropical eutrophic pond in China. Bubble emissions of CH4 accounted for 99.7 and 91.67% of the total CH4 emission measured at two sites in the summer; however, no bubble was observed in the autumn. The pond was supersaturated with CO2 and CH4 during the monitoring period, and the saturation ratios (i.e. observed concentration/equilibrium concentration) of CH4 were much higher than that of CO2. Although the concentration of dissolved CO2 in the surface water collected in the autumn was 1.24 times of that in the summer, the mean diffusive CO2 flux across the water–air interface measured in the summer is almost twice compared with that in the autumn. The mean concentration of dissolved CH4 in the surface water in the autumn was around half of that in the summer, but the mean diffusive CH4 flux in the summer is 4–5 times of that in the autumn. Our data showed that the variation in gas exchange rate was dominated by differences in weather patterns and primary production. Averaged k600-CO2 and k600-CH4 (the gas transfer velocity normalised to a Schmidt number of 600) were 0.65 and 0.55 cm/h in the autumn, and 2.83 and 1.64 cm/h in the summer, respectively. No statistically significant correlation was found between k600 and U10 (wind speed at 10 m height) in the summer at low wind speeds in clear weather. Diffusive gas fluxes increased during the nights, which resulted from the nighttime cooling effect of water surface and stronger turbulent mixing in the water column. The chemical enhancements for CO2 were estimated up to 1.94-fold in the hot and clear summer with low wind speeds, which might have been resulted from the increasing hydration reactions in water due to the high water temperature and active metabolism in planktonic algae. However, both the air and surface water temperatures decreased continually, and relatively lower temperature and overcast weather with occasionally light rain dominated the second campaign in the autumn. The concentration of dissolved oxygen in the surface water and U10 controlled gas transfer velocities of CO2 and CH4, respectively, in the cool autumn. When the surface water temperature was higher than the air temperature, higher CO2 flux was observed because the water body was unstable and overturned quickly, inducing quick CO2 emitted from plankton algae in surface water to the atmosphere.

赤潮过程中“藻-菌”关系的研究进展

微生物对促进海洋物质循环，维持水生环境的生态平衡具有重要作用。在赤潮事件中，基于微生物（尤其是细菌）的多样性和重要性，它们与藻类之间的相互关系成为了研究的热点。过去20年里，人们从不同角度对“藻-菌”间的关系进行了探索，包括物理学过程、生物学过程、环境过程以及化学过程。就化学过程而言，它作为一种较早出现的技术，在以往的研究中带给人们许多认识藻菌关系的方法。随着学科的渗透，化学法有了拓展与延伸，为人们认识藻菌关系带来了新的契机。从化学生态学领域来梳理“藻．菌”关系中涉及的现象和行为，包括菌对藻的有益面、菌对藻的有害面、以及藻类应答细菌行为的化学途径；并从信号语言（群体感应、化感作用）的角度来阐释两者之间的互生或克生关系。通过文献综述的方式来解读藻菌关系的互作过程和机理，为认识赤潮的发生和防控方法提供借鉴。

Deciphering the genetic basis of microcystin tolerance.

BackgroundCyanobacteria constitute a serious threat to freshwater ecosystems by producing toxic secondary metabolites, e.g. microcystins. These microcystins have been shown to harm livestock, pets and humans and to affect ecosystem service and functioning. Cyanobacterial blooms are increasing worldwide in intensity and frequency due to eutrophication and global warming. However, Daphnia, the main grazer of planktonic algae and cyanobacteria, has been shown to be able to suppress bloom-forming cyanobacteria and to adapt to cyanobacteria that produce microcystins. Since Daphnia’s genome was published only recently, it is now possible to elucidate the underlying molecular mechanisms of microcystin tolerance of Daphnia.ResultsDaphnia magna was fed with either a cyanobacterial strain that produces microcystins or its genetically engineered microcystin knock-out mutant. Thus, it was possible to distinguish between effects due to the ingestion of cyanobacteria and effects caused specifically by microcystins. By using RNAseq the differentially expressed genes between the different treatments were analyzed and affected KOG-categories were calculated. Here we show that the expression of transporter genes in Daphnia was regulated as a specific response to microcystins. Subsequent qPCR and dietary supplementation with pure microcystin confirmed that the regulation of transporter gene expression was correlated with the tolerance of several Daphnia clones.ConclusionsHere, we were able to identify new candidate genes that specifically respond to microcystins by separating cyanobacterial effects from microcystin effects. The involvement of these candidate genes in tolerance to microcystins was validated by correlating the difference in transporter gene expression with clonal tolerance. Thus, the prevention of microcystin uptake most probably constitutes a key mechanism in the development of tolerance and adaptation of Daphnia. With the availability of clear candidate genes, future investigations examining the process of local adaptation of Daphnia populations to microcystins are now possible.Electronic supplementary materialThe online version of this article (doi:10.1186/1471-2164-15-776) contains supplementary material, which is available to authorized users.

查干湖湿地浮游植物与环境因子关系的多元分析

This study investigated the biodiversity and community structures of phytoplankton and their relations with environmental factors in Chagan Lake during the intermediate( May) and rainy season( September) in 2012. Combining field investigations with cluster analysis,multi-dimensional scaling( MDS) analysis and redundancy analysis( RDA),and applying Shannon,Pielou and Margalef indices,the study identified a total of 127 phytoplankton species( belonging to 53genera and 5 phyla). Among these species,52 were members of Bacillariophyta,46 Chlorophyta,and 25 Cyanophyta,accounting for 40.94%,36.22%,and 19.69% of the total phytoplankton species,respectively. In terms of algal populationdistribution,in the intermediate season Cyanophyta was the most abundant phylum of planktonic algae( accounting for 39.85% of algal population),followed by Bacillariophyta( 36. 193%) and Chlorophyta( 21. 33%),whereas in the rainy season Chlorophyta( 70. 84%) was the dominant phylum. Consisting of two connected parts( the main lake body and Xinmiao wetland),Chagan lake was found to sustain significant temporal-spatial variations of phytoplankton populations.The abundance of phytoplankton in the intermediate season( averaging 658.0 × 104cells /L) was considerably higher than that in the rainy season( averaging 459. 3 × 104cells /L). In both seasons,phytoplankton abundance was found to be positively correlated with water salinity( i. e. greater salinity coinciding with higher phytoplankton populations),and negatively affected by pH and phosphate( PO3-4) concentration in the intermediate season. In either season,the abundance of phytoplankton in the main lake was 8-10 times of that in Xinmiao wetland. In the intermediate season,such discrepancy was caused by different salinity and nutrients in these two water bodies; salinity in the main lake( 52.0 mg /L) was 3.3times of that in Xinmiao wetland( 16. 0 mg /L),whilst PO3-4in the main lake( 0. 045 mg /L) was 3. 8 times of its concentration in Xinmiao wetland. In the rainy season,there was no significant difference in nutrient levels in the whole lake,so water salinity was the main factors affecting the distribution of phytoplankton. In addition to field investigation results,cluster and MDS analyses based on Bray-Curtis measures of similarity also illustrated significant discrepancy between the main lake and Xinmiao wetland in terms of phytoplankton abundance. RDA results indicated that in the intermediate season the key environmental factors influencing the phytoplankton assemblages were pH,total nitrogen( TN)and phosphate( PO3-4),whereas salinity,phosphate( PO3-4) and 5-day biological oxygen demand( BOD5) were the key factors in the rainy season. In the intermediate season,dominant phytoplankton genera were those favoring low alkalinity,low phosphorus and high nitrogen levels. Rainy season benefitted genera that were more tolerant alkalinity,salinity,phosphorus and BOD5. Most dominant genera indentified in this study were micro-phytoplankton,common in temperate climate and capable of rapid multiplying and fast growing through nutrient assimilation,could form a higher abundance in rich nutrients. When phytoplankton was used as a bio-indicator in water quality evaluation,the results revealed that water quality in Chagan Lake was in β-moderately-polluted category.

In situ production of charophyte communities under reduced light conditions in a brackish-water ecosystem

INTRODUCTION Charophyte communities are an important element in shallow enclosed fresh- and brackish-water ecosystems (Mathieson and Nienhuis, 1991; van den Berg et al., 1998; Pelechaty et al., 2006). They provide shelter and habitat for numerous species including epiphytic microalgae, filamentous macroalgae, as well as various crustacean and insect species (Linden et al., 2003; Schmieder et al., 2006; Torn et al., 2010). Besides, charophytes are an important component in the food web as part of the diet of benthic invertebrates (Kotta et al., 2004, 2013), waterfowl (Noordhuis et al., 2002; Schmieder et al., 2006), and fish and fish larvae (de Winton et al., 2002; Dugdale et al., 2006). Declining distribution and diversity of charophytes have been observed in many regions worldwide including the brackish Baltic Sea (Blindow, 2000, 2001; Schubert and Blindow 2003; Munsterhjelm, 2005). Eutrophication is assumed to be the most important threat to charophytes causing their decline (e.g. Blindow, 1992; Auderset Joye et al., 2002). The main effect associated with eutrophication is the bloom of ephemeral planktonic algae, which leads to increased sedimentation, water turbidity and, as a result, reduced light availability. The shortage of light may reduce the photosynthetic production and growth of charophytes down to the level where their sustainable development becomes impossible (Blindow et al., 2002; Johnsen and Sosik, 2004; Hautier et al., 2009; Dickey et al., 2011). On the other hand, charophytes often prefer soft bottom habitats where even moderate wind may cause sediment resuspension and sedimentation of particles on the plant surface. In such habitats underwater light climate is naturally very variable (Schneider et al., 2006 and references therein). Thus, charophytes are adapted to periodic stress of low light intensities. Nevertheless, the interactive effect of elevated eutrophication and weather variables may result in poorer light conditions than expected from their separate effects (Blindow et al., 2003; Kling et al., 2003). So far, the studies concerning photosynthesis of charophytes are mainly based on laboratory experiments with either detached pieces or single individuals (e.g. Blindow et al., 2003; Marquardt and Schubert, 2009). Very few have been carried out in the natural environments, especially in brackish bodies of water. As compared to their freshwater counterparts, charophytes are often naturally stressed at elevated salinity and therefore are expected to respond differently to changes in light conditions (e.g. Blindow et al., 2003). The existing data on in situ primary production of charophytes related to light limitation are scarce and hardly comparable because of difference in methodologies and the environmental conditions among habitats (Kufel and Kufel, 2002). Light is a key limiting factor for photosynthetic production in aquatic environments (Kurtz et al., 2003; Asaeda et al., 2004, Binzer et al., 2006; Zhang et al., 2010). Earlier experimental studies carried out at the community level have also shown that canopy density and canopy structure significantly affect the photosynthetic production of marine macroalgae (Middelboe et al., 2006). This suggests that macroalgal communities are largely light-limited and such light limitation increases with canopy height and/or community biomass (Parnoja et al., 2013). Altough the photosynthetic production of marine macroalgae at the community level has been increasingly studied (Middelboe and Binzer, 2004; Middelboe et al., 2006; Parnoja et al., 2013), to the best of our knowledge, there is only a single study on charophyte communities (Libbert and Walter, 1985). Based on the above, our goal was to determine the primary production of a charophyte community under manipulated in situ light conditions. We hypothesized that (a) the community would have higher responses under more severe light limitation and (b) the recovery of charophyte photosynthetic performance would be faster under less severe disturbances. …

Seasonal Dynamics of the Quantitative Indices of Phytoplankton Development in the Upper Section of the Southern Bug River

Ye. P. Belous, T. F. Shevchenko & P. D. KlochenkoInstitute of HydrobiologyNational Academy of Sciences of UkraineKiev, UkraineSeasonal dynamics of plankton algae species number, their numbers andbiomass, and also of the complex of dominant species, were studied in the uppersection of the Southern Bug River located within the territory of the town ofKhmelnitskiy. Several peaks of algae development were revealed during theperiodofinvestigations.Thehighestnumberofphytoplanktonspeciescausedbya sharp increase in the number of green algae species was registered in July. Themaximum numbers of phytoplankton conditioned by the development ofblue-green algae were observed also in July. Seasonal dynamics ofphytoplankton biomass were characterized by the presence of two peaks. Thefirst peak conditioned by the development of diatoms was registered in June,whereas the second peak caused by intensive development of Dinophyta andBacillariophyta – in September.

한반도 서남부 하천 하구역의 수질 및 부착돌말 군집 특성

Environmental factors and epilithic diatom communities in the lower streams near the harbor regionof South Korean peninsula were examined during no monsoon period in May 2013. The sampling of water andepilithic diatoms was conducted at both streams, 19 regulated streams(RS) that there are one or several damsconstructedin the river system, and 19 un-regulated streams(US) that there are no dams within the river. Acluster analysis based on the number of species and abundance of epilithic diatoms through the stations, dividedinto three groupssuch as groups I(mainly US), II(mixed with US and RS) and III(mainly RS), respectively.Group I showed that water quality is good and high diversity of diatom, while Group II and III was waterquality is relatively poor, but not differed in biomass of diatom from Group I. In addition, Group II that had highconductivity, nitrogen and phosphorus, was the lowest in diatom diversity among them. Dominant specieswere Nitzschia palea(17%) and Navicula seminuloides(11%) in Group I, Nitzschia inconspicua(19%) andNavicula perminuta(9%) in Group II, and Nitzschia inconspicua(15%) and Nitzschia palea(14%) in GroupIII, respectively. These taxa were widely distributed in brackish water, and not closely related with specificwater quality, like eutrophic water. However, the groups II and III belonged to RS, had not only little biomass,but bad water quality such as high concentrations of nutrient and chlorophyll-a. Therefore, to determine theeffect of dam construction on the lower water ecosystem, the planktonic algae, which can occur algal bloom inthe estuary, also was considered to be a parallel investigation.

Community Structure of Planktonic Algae in Pagpanganan River, Baybay City, Leyte

Planktonic algae are free-floating phytoplankton that abound in aquatic and marine environments. They are the primary producers of aquatic ecosystems thus their role in the ecosystem cannot be overemphasized. This study was conducted in three sites of Pagbanganan River to determine the abundance and diversity of planktonic algae. A total of 39 genera under divisions Bacillariophyta, Chlorophyta, Cyanophyta and Charophyta were recorded. The most abuntat and dominant group were the diatoms (Divion Bacillariophyta). Navicula, Nitzschia, Synedra, Melosira and Coconies were the most abundant genera. The upstream, midstream and downstream sites were highly similar in phytoplankton composition and abundance. Phytoplankton were more abundant and dominant but less diverse during the months of April, May and June compared to July, August and September. Temperature, dissolved oxygen and nitrate levels were within safe limits but phosphate was in excess. Abundace was positively correlated with current velocity but negatively correlated with nitrate level.

Problem of ecological safety of aquatic environment in conditions of anthropogenic eutrophication

The state of any aquatic ecosystem, its trophic level, pollution degree and other constituents of environmental monitoring are reliably characterized by means of studying and monitoring the species composition and the number of planktonic algae. The most typical negative anthropogenic impact on the aquatic environment is drastic propagation of phytoplankton, called ''algal bloom''. It is caused mainly by the flow of nutrients into the water, which stimulate the intensive propagation of algae. Another factor that influences phytoplankton propagation is temperature. In this regard, the important question is the effect of temperature on the dynamics of phytoplankton expansion in aquatic ecosystems.The correlation analysis of algae propagation depending on the water temperature in a water intake (for example, the reservoir of the Teteriv River, a tributary of the Dnieper River) was made in the paper. The analysis indicated a significant influence of the temperature on algae propagation that allowed using trigonometric series in mathematical description of the dynamics of their propagation.According to the studies, an adequate mathematical model describing the dynamics of phytoplankton expansion in aquatic ecosystems was developed and its adequacy (model relative error) was estimated. The analysis of the relative error shows that the developed mathematical model adequately describes the dynamics of phytoplankton expansion in aquatic ecosystems. It should be noted that the proposed model can be simplified. However, this will increase the relative error, and, therefore, the model will not adequately correspond to the original.

Planktonic algae and cyanoprokaryotes as indicators of ecosystem quality in the Mooi River system in the North-West Province, South Africa

An ecologically healthy Mooi River system is important for maintaining the quality of potable water of Potchefstroom and surrounding areas. However, this system is under constant threat from anthropogenic pollution arising from both agricultural and mining activities in its catchment. A survey of planktonic algal and cyanoprokaryote assemblages in Klerkskraal, Boskop and Potchefstroom reservoirs was undertaken during 1999–2000 and 2010–2011. In all three dams, total algal and cyanoprokaryote concentrations were lower during the second survey (2010–2011), suggesting an improvement in ecosystem health. However, results also show a change from a Chrysophyceae-dominated community to one dominated by Bacillariophyceae. Increased numbers of diatom species that usually occur in eutrophic impoundments (Melosira varians, Cyclotella meneghiniana and Aulacoseira granulata) indicate an increase in the trophic status of the reservoirs, especially that of Boskop Dam, a trend mirrored by increases in conductivity as well as phosphorus and ammonium concentrations in all three reservoirs. It can therefore be concluded that although the ecosystem health of the Mooi River system is currently still good, further increases in nutrients such as phosphorus can cause proliferation of problem species (detected in enrichment cultures) and a deterioration of its water quality.Keywords: Mooi River reservoirs, algal communities, cyanoprokaryotes, water quality