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Sample records for eutrophic shallow lake

  1. Dynamics of particulate phosphorus in a shallow eutrophic lake

    Energy Technology Data Exchange (ETDEWEB)

    Shinohara, Ryuichiro, E-mail: r-shino@nies.go.jp [National Institute for Environmental Studies, 16-2 Onogawa, Tsukuba, Ibaraki 305-8506 (Japan); Imai, Akio; Kohzu, Ayato; Tomioka, Noriko [National Institute for Environmental Studies, 16-2 Onogawa, Tsukuba, Ibaraki 305-8506 (Japan); Furusato, Eiichi [Graduate School of Science and Engineering, Saitama University, 255 Shimo-okubo, Sakura-ku, Saitama 338-8570 (Japan); Satou, Takayuki; Sano, Tomoharu; Komatsu, Kazuhiro; Miura, Shingo; Shimotori, Koichi [National Institute for Environmental Studies, 16-2 Onogawa, Tsukuba, Ibaraki 305-8506 (Japan)

    2016-09-01

    We tested the hypothesis that in shallow, eutrophic Lake Kasumigaura, the concentration of particulate phosphorus (PP) is controlled by biogenic P (P in living or dead phytoplankton and bacterial cells), rather than by resuspension of inorganic P in sediment. Increases in wind velocity and turbidity were associated with bottom shear stress exceeding the critical value for the lake (τ{sub c} = 0.15 N m{sup −2}); this increased turbidity was due to sediment resuspension. However, concentrations of PP; HCl-extractable, reactive P in PP (P-rP); and HCl-extractable, non-reactive P in PP (P-nrP) were not correlated with wind velocity (PP vs. wind velocity: r = 0.40, p > 0.05). Rather, the P-nrP concentration accounted for approximately 79% of PP, and the concentrations of PP, P-rP, and P-nrP were correlated with the particulate organic carbon (POC) concentration (POC vs. PP: r = 0.90, p < 0.01; POC vs. P-rP: r = 0.82, p < 0.01; POC vs. P-nrP: r = 0.86, p < 0.01). In our {sup 31}P nuclear magnetic resonance spectroscopy results, mononucleotides accounted for the largest proportion among the detected P compound classes. In addition, concentrations of mononucleotides, orthophosphate, and pyrophosphate were significantly higher in samples with high POC concentrations, whereas the DNA-P concentration was not. These results suggest that biogenic P affects PP concentrations more strongly than does sediment resuspension, and the production of biogenic P creates a pool of mononucleotides, a class of easily degradable P, even in shallow, eutrophic Lake Kasumigaura. - Highlights: • Biogenic P affected the PP concentration more than did sediment resuspension. • PP correlated with particulate organic carbon concentration but not wind velocity. • Mononucleotides accounted for the largest P compound class of organic P in PP.

  2. Macrophytes and periphyton carbon subsidies to bacterioplankton and zooplankton in a shallow eutrophic lake in tropical China

    NARCIS (Netherlands)

    de Kluijver, A.; Ning, J.; Liu, Z.; Jeppesen, E.; Gulati, R.D.; Middelburg, J.J.

    The subsidy of carbon derived from macrophytes and associated periphyton to bacterioplankton and zooplankton in subtropical shallow eutrophic Huizhou West Lake in China was analyzed using carbon stable isotope signatures. A restored part of the lake dominated by macrophytes was compared with an

  3. Macrophytes and periphyton carbon subsidies to bacterioplankton and zooplankton in a shallow eutrophic lake in tropical China

    NARCIS (Netherlands)

    de Kluijver, A.; Ning, J.; Liu, Z.; Jeppesen, E.; Gulati, R.D.; Middelburg, J.J.

    2015-01-01

    The subsidy of carbon derived from macrophytes and associated periphyton to bacterioplankton and zooplankton in subtropical shallow eutrophic Huizhou West Lake in China was analyzed using carbon stable isotope signatures. A restored part of the lake dominated by macrophytes was compared with an

  4. Water quality in simulated eutrophic shallow lakes in the presence of periphyton under different flow conditions.

    Science.gov (United States)

    Chen, Shu; Yang, Guolu; Lu, Jing; Wang, Lei

    2018-02-01

    Although the effects of periphyton on water quality and its relationship with flow conditions have been studied by researchers, our understanding about their combined action in eutrophic shallow lakes is poor. In this research, four aquatic model ecosystems with different water circulation rates and hydraulic conditions were constructed to investigate the effect of periphyton and flow condition on water quality. The concentrations of NH 4 + , TP, and chlorophyll-a and flow conditions were determined. The results show that, as a result of the rising nutrient level at the early stage and the decline in the lower limit, the presence of periphyton can make the ecosystem adaptable to a wider range of nutrients concentration. In terms of the flow condition, the circulation rate and hydraulic condition are influential factors for aquatic ecosystem. Higher circulation rate in the ecosystem, on one hand, facilitates the metabolism by accelerating nutrient cycling which is beneficial to water quality; on the other hand, high circulation rate leads to the nutrient lower limit rising which is harmful to water quality improvement. At low velocities, slight differences in hydraulic conditions, vertical velocity gradient and turbulence intensity gradient could affect the quantity of phytoplankton. Our study suggests that, considering environmental effect of periphyton, flow conditions and their combined action is essential for water quality improvement and ecological restoration in eutrophic shallow lakes.

  5. Vertical distribution and community composition of anammox bacteria in sediments of a eutrophic shallow lake.

    Science.gov (United States)

    Qin, H; Han, C; Jin, Z; Wu, L; Deng, H; Zhu, G; Zhong, W

    2018-07-01

    The aim of this study was to explore the vertical distribution traits of anaerobic ammonium-oxidizing (anammox) bacterial relative abundance and community composition along the oxic/anoxic sediment profiles in a shallow lake. The Illumina Miseq-based sequencing and quantitative polymerase chain reactions were utilized to analyse relative abundance of anammox hydrazine synthase (hzsB) gene in comparison with bacterial 16S rRNA genes, anammox bacterial relative abundance (the number of anammox sequences divided by total number of sequences), community composition and diversity in sediments. The relative abundance of hzsB gene at the low-nitrogen (LN) site in the lake sediments showed that the vertical distribution of anammox bacteria increased to a peak, then decreased with increasing depth. Moreover, the relative abundance of hzsB gene at the high-nitrogen site was significantly lower than that at the LN site. Additionally, the community composition results showed that Candidatus Brocadia sp. was the dominant genus. In addition, the anammox bacterial diversity was also site specific. Redundancy analysis showed that the total N and the NH 4 + -N content might be the most important factors affecting anammox bacterial community composition in the studied sites. The results revealed the specific vertical variance of anammox bacterial distribution and community composition in oxic/anoxic sediments of a eutrophic shallow lake. This is the first study to demonstrate that anammox bacteria displayed the particular distribution in freshwater sediments, which implied a strong response to the anthropogenic eutrophication. © 2018 The Society for Applied Microbiology.

  6. The contribution of phytoplankton degradation to chromophoric dissolved organic matter (CDOM) in eutrophic shallow lakes: Field and experimental evidence

    NARCIS (Netherlands)

    Zhang, Y.; Van Dijk, M.A.; Liu, M.; Zhu, G.; Qin, B.

    2009-01-01

    Eight field campaigns in the eutrophic, shallow, Lake Taihu in the summers from 2005 to 2007, and a phytoplankton degradation experiment of 33 days, were carried out to determine the contribution of phytoplankton degradation to CDOM. Significant and positive correlations were found between the CDOM

  7. Variations of alkaline phosphatase activity and P fractions in sediments of a shallow Chinese eutrophic lake (Lake Taihu)

    International Nuclear Information System (INIS)

    Zhang Tingxi; Wang Xiaorong; Jin Xiangcan

    2007-01-01

    The distribution of alkaline phosphatase activity (APA) and P fractions in sediment cores and the relationship between them were studied in a shallow Chinese freshwater lake (Lake Taihu). Sediment cores were collected from four sites, characterized by different degrees of eutrophication in June 2004. Sediment P was fractionated into Fe/Al-P, Ca-P, organic P (OP), inorganic P (IP) and total P (TP). The former two species made the largest contribution to the sediment P pool. Results show that trophic status and hydrological conditions have great impact on the APA of the sediments. The order of the APA in sediments was conjectured to be: macrophyte dominated lake > transitional lake > algal dominated lake. APA profiles follow a similar downcore decreasing trend. There was a positive relationship between the APA and the TP, IP. The multiple linear regression equation of the APA and P fractions is: APA = -97 + 0.768TP - 0.985Fe/Al-P. - Characteristics of the alkaline phosphatase activity and P fractions in sediments of different trophic status lake were studied in Lake Taihu

  8. Restoration and Purification of Dissolved Organic Nitrogen by Bacteria and Phytoremediation in Shallow Eutrophic Lakes Sediments

    Science.gov (United States)

    Li, Xin; Yue, Yi

    2018-06-01

    Endogenous organic nitrogen loadings in lake sediments have increased with human activity in recent decades. A 6-month field study from two disparate shallow eutrophic lakes could partly reveal these issues by analysing seasonal variations of biodegradation and phytoremediation in the sediment. This paper describes the relationship between oxidation reduction potential, temperature, microbial activity and phytoremediation in nitrogen cycling by calculation degradative index of dissolved organic nitrogen and amino acid decomposition. The index was being positive in winter and negative in summer while closely positive correlated with biodegradation. Our analysis revealed that rather than anoxic condition, biomass is the primary factor to dissolved organic nitrogen distribution and decomposition. Some major amino acids statistics also confirm the above view. The comparisons of organic nitrogen and amino acid in abundance and seasons in situ provides that demonstrated plants cue important for nitrogen removal by their roots adsorption and immobilization. In conclusion, enhanced microbial activity and phytoremediation with the seasons will reduce the endogenous nitrogen loadings by the coupled mineralization and diagenetic process.

  9. Interactions between fishes and the structure of fish communities in Dutch shallow, eutrophic lakes

    NARCIS (Netherlands)

    Lammens, E.

    1986-01-01

    This thesis describes the structure of fish communities in Tjeukemeer (21 km 2) and some other surrounding very eutrophic lakes and emphasizes the interactions of the fishes with each other and their food organisms (predation and (exploitative) competition). It is a compilation of seven

  10. Resilience of alternative stable states during the recovery of shallow lakes from eutrophication: Lake Veluwe as a case study

    NARCIS (Netherlands)

    Ibelings, B.W.; Portielje, R.; Lammens, E.H.R.R.; Meijer, M.L.; Noordhuis, R.; van den Berg, Marcel S.; Joosse, W.; Scheffer, M.

    2007-01-01

    In this paper we analyze a long-term dataset on the recovery from eutrophication of Lake Veluwe (The Netherlands). Clear hysteresis was observed in a number of ecosystem variables: the route to recovery differed significantly from the route that led to loss of clear water. The macrophyte dominated

  11. Could artificial plant beds favour microcrustaceans during biomanipulation of eutrophic shallow lakes?

    DEFF Research Database (Denmark)

    Balayla, David; Boll, Thomas; Trochine, Carolina

    2017-01-01

    Introduction of artificial plants may facilitate the transition from a turbid to a clear-water state in shallow lakes, particularly when plant establishment is delayed. We investigated the usefulness of artificial plants as a restoration tool in an experimental setup mimicking open submerged plant...

  12. Precipitation and temperature drive seasonal variation in bioaccumulation of polycyclic aromatic hydrocarbons in the planktonic food webs of a subtropical shallow eutrophic lake in China.

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    Tao, Yuqiang; Yu, Jing; Xue, Bin; Yao, Shuchun; Wang, Sumin

    2017-04-01

    Hydrophobic organic contaminants (HOCs) are toxic and ubiquitous in aquatic environments and pose great risks to aquatic organisms. Bioaccumulation by plankton is the first step for HOCs to enter aquatic food webs. Trophic status is considered to dominate variations in bioaccumulation of HOCs in plankton in temperate and frigid deep oligotrophic waters. However, long-term driving factors for bioaccumulation of HOCs in planktonic food webs of subtropical shallow eutrophic waters have not been well investigated. China has the largest subtropical lake density in the Northern Hemisphere. Due to limited field data, long-term variations in the bioaccumulation of HOCs in these lakes are almost unknown. Here we take Lake Xuanwu as an example to investigate long-term variations in the bioaccumulation, and biomagnification of polycyclic aromatic hydrocarbon (PAHs) in planktonic food webs of subtropical shallow eutrophic lakes in China, and elucidate the driving factors. Our results indicate that temperature rather than nutrients dominates long-term dynamics of planktonic biomass in this lake. Precipitation significantly enhances the concentrations of the PAHs, and total suspended particles, and consequently affects the distribution of the PAHs in the water column. Biomass dilution induced by temperature dominates bioaccumulation of the PAHs by both phytoplankton and zooplankton (copepods and cladocerans). Biomagnification of the PAHs from phytoplankton to zooplankton is positively correlated with temperature. Our study suggests that temperature and precipitation drive long-term variations in the bioaccumulation of the PAHs in the planktonic food webs of this subtropical shallow eutrophic lake. Lake Xuanwu has a similar mean annual temperature, annual precipitation, sunshine duration, and nutrient levels as other subtropical shallow eutrophic lakes in China. This study may also help to understand the bioaccumulation of HOCs in planktonic food webs of other subtropical shallow

  13. Characterization, origin and aggregation behavior of colloids in eutrophic shallow lake.

    Science.gov (United States)

    Xu, Huacheng; Xu, Mengwen; Li, Yani; Liu, Xin; Guo, Laodong; Jiang, Helong

    2018-05-31

    Stability of colloidal particles contributes to the turbidity in the water column, which significantly influences water quality and ecological functions in aquatic environments especially shallow lakes. Here we report characterization, origin and aggregation behavior of aquatic colloids, including natural colloidal particles (NCPs) and total inorganic colloidal particles (TICPs), in a highly turbid shallow lake, via field observations, simulation experiments, ultrafiltration, spectral and microscopic, and light scattering techniques. The colloidal particles were characterized with various shapes (spherical, polygonal and elliptical) and aluminum-, silicon-, and ferric-containing mineralogical structures, with a size range of 20-200 nm. The process of sediment re-suspension under environmentally relevant conditions contributed 78-80% of TICPs and 54-55% of NCPs in Lake Taihu, representing an important source of colloids in the water column. Both mono- and divalent electrolytes enhanced colloidal aggregation, while a reverse trend was observed in the presence of natural organic matter (NOM). The influence of NOM on colloidal stability was highly related to molecular weight (MW) properties with the high MW fraction exhibiting higher stability efficiency than the low MW counterparts. However, the MW-dependent aggregation behavior for NCPs was less significant than that for TICPs, implying that previous results on colloidal behavior using model inorganic colloids alone should be reevaluated. Further studies are needed to better understand the mobility/stability and transformation of aquatic colloids and their role in governing the fate and transport of pollutants in natural waters. Copyright © 2018. Published by Elsevier Ltd.

  14. Response of Zooplankton to Climate Variability: Droughts Create a Perfect Storm for Cladocerans in Shallow Eutrophic Lakes

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    Gaohua Ji

    2017-10-01

    Full Text Available A major attribute of the Earth’s climate that may be affected by global warming is the amplitude of variability in teleconnections. These global-scale processes involve links between oceanic conditions in one locale and weather in another, often distant, locale. An example is the El Niño Southern Oscillation (ENSO, which can affect rainfall and then the properties of lakes in Europe, Africa, North and South America. It affects rainfall, droughts and the depth of lakes in Florida, USA. It is predicted that the amplitude of variation in the ENSO will increase with global warming and, therefore, droughts will become more severe and periods of rain more intense. We investigated possible effects of climate on the zooplankton in shallow subtropical lakes by studying 16 years of monthly data from six shallow eutrophic lakes located north of Orlando, Florida. Results indicate that water depth and lake volume are tightly coupled with rainfall, as expected. During droughts, when lake depth and volume were greatly reduced, there were intensified cyanobacterial blooms, and the zooplankton shifted towards greater relative biomass of copepods compared to cladocerans. The change of zooplankton was likely due to the intensified selective fish predation in the reduced water volume, and/or selective adverse effects of cyanobacteria on cladocerans. The greatly reduced volume might lead to a ‘perfect storm’ of top-down and bottom-up factors that favor copepods over cladocerans. The mechanism needs further study. Regardless, this study documents a direct link between climate variability and zooplankton composition, and suggests how future changes in climate might affect plankton communities.

  15. Long-term effects of extreme weather events and eutrophication on the fish community of shallow Lake Peipsi (Estonia/Russia

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    Külli Kangur

    2013-06-01

    Full Text Available The fish kill in lake Peipsi (Estonia/Russia during the extraordinarily hot summer of 2010 evoked an investigation into the effects of environmental extremes and long-term eutrophication on the fish community of the lake. Current data on lake Peipsi indicate that temperature extremes and synergistic interactions with eutrophication have led to a radical restructuring of the fish community. Commercial landings of lake smelt, Osmerus eperlanus eperlanus m. spirinchus (Pallas, the previous dominant species of the fish community, have decreased dramatically since the 1930s, these declines being coupled with summer heat waves coinciding with low water levels. Gradual decline in smelt stock and catches was significantly related to a decline of near-bottom oxygen conditions and to a decrease in water transparency. The first documented fish kill in 1959 occurred only in the southern, most shallow and eutrophic lake (lake Pihkva. Recently, summer fish kill have become more frequent, involving larger areas of the lake. In addition to the cold-water species, e.g. smelt and vendace Coregonus albula (L., the abundance of bottom-dwelling fishes such as ruffe Gymnocephalus cernuus (L. and juvenile fish have significantly decreased after the 2010 heat wave probably due to hypoxia and warm water temperatures. This study showed that fish community structure in large shallow lakes may be very vulnerable to water temperature increases, especially temperature extremes in combination with eutrophication.

  16. Mapping Aquatic Vegetation in a Large, Shallow Eutrophic Lake: A Frequency-Based Approach Using Multiple Years of MODIS Data

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    Xiaohan Liu

    2015-08-01

    Full Text Available Aquatic vegetation serves many important ecological and socioeconomic functions in lake ecosystems. The presence of floating algae poses difficulties for accurately estimating the distribution of aquatic vegetation in eutrophic lakes. We present an approach to map the distribution of aquatic vegetation in Lake Taihu (a large, shallow eutrophic lake in China and reduce the influence of floating algae on aquatic vegetation mapping. Our approach involved a frequency analysis over a 2003–2013 time series of the floating algal index (FAI based on moderate-resolution imaging spectroradiometer (MODIS data. Three phenological periods were defined based on the vegetation presence frequency (VPF and the growth of algae and aquatic vegetation: December and January composed the period of wintering aquatic vegetation; February and March composed the period of prolonged coexistence of algal blooms and wintering aquatic vegetation; and June to October was the peak period of the coexistence of algal blooms and aquatic vegetation. By comparing and analyzing the satellite-derived aquatic vegetation distribution and 244 in situ measurements made in 2013, we established a FAI threshold of −0.025 and VPF thresholds of 0.55, 0.45 and 0.85 for the three phenological periods. We validated the accuracy of our approach by comparing the results between the satellite-derived maps and the in situ results obtained from 2008–2012. The overall classification accuracy was 87%, 81%, 77%, 88% and 73% in the five years from 2008–2012, respectively. We then applied the approach to the MODIS images from 2003–2013 and obtained the total area of the aquatic vegetation, which varied from 265.94 km2 in 2007 to 503.38 km2 in 2008, with an average area of 359.62 ± 69.20 km2 over the 11 years. Our findings suggest that (1 the proposed approach can be used to map the distribution of aquatic vegetation in eutrophic algae-rich waters and (2 dramatic changes occurred in the

  17. The contribution of phytoplankton degradation to chromophoric dissolved organic matter (CDOM) in eutrophic shallow lakes: field and experimental evidence.

    Science.gov (United States)

    Zhang, Yunlin; van Dijk, Mark A; Liu, Mingliang; Zhu, Guangwei; Qin, Boqiang

    2009-10-01

    Eight field campaigns in the eutrophic, shallow, Lake Taihu in the summers from 2005 to 2007, and a phytoplankton degradation experiment of 33 days, were carried out to determine the contribution of phytoplankton degradation to CDOM. Significant and positive correlations were found between the CDOM absorption coefficient at 355 nm [a(CDOM)(355)], normalized fluorescence emission (QSU) at 450 nm from excitation at 355 nm [F(n)(355)], and the chlorophyll a (Chla) concentration for all eight field campaigns, which indicates that the decomposition and degradation of phytoplankton is an important source of CDOM. In the degradation experiment, the CDOM absorption coefficient increased as phytoplankton broke down during the first 12 days, showing the production of CDOM from phytoplankton. After 12 days, a(CDOM)(355) had increased from the initial value 0.41+/-0.03 m(-1) to 1.37+/-0.03 m(-1) (a 234% increase), and the Chla concentration decreased from the initial value of 349.1+/-11.2 microg/L to 30.4+/-13.2 microg/L (a 91.3% decrease). The mean daily production rate of CDOM from phytoplankton was 0.08 m(-1) for a(CDOM)(355). Parallel Factor Analysis (PARAFAC) was used to assess CDOM composition from EEM spectra, and four components were identified: a terrestrial-like humic component, two marine-like humic components, and a protein-like component. The rapid increase in marine-like humic fluorophores (C3 and C4) during the degradation experiment suggests that in situ production of CDOM plays an important role in the dynamics of CDOM. The field campaigns and experimental data in the present study show that phytoplankton can be one of the important CDOM producers in eutrophic shallow lakes.

  18. Is Lake Chabot Eutrophic?

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    Pellegrini, K.; Logan, J.; Esterlis, P.; Lew, A.; Nguyen, M.

    2013-12-01

    Introduction/Abstract: Lake Chabot is an integral part of the East Bay watershed that provides habitats for animals and recreation for humans year-round. Lake Chabot has been in danger of eutrophication due to excessive dumping of phosphorous and nitrogen into the water from the fertilizers of nearby golf courses and neighboring houses. If the lake turned out to be eutrophified, it could seriously impact what is currently the standby emergency water supply for many Castro Valley residents. Eutrophication is the excessive richness of nutrients such as nitrogen and phosphorus in a lake, usually as a result of runoff. This buildup of nutrients causes algal blooms. The algae uses up most of the oxygen in the water, and when it dies, it causes the lake to hypoxify. The fish in the lake can't breathe, and consequently suffocate. Other oxygen-dependant aquatic creatures die off as well. Needless to say, the eutrophication of a lake is bad news for the wildlife that lives in or around it. The level of eutrophication in our area in Northern California tends to increase during the late spring/early summer months, so our crew went out and took samples of Lake Chabot on June 2. We focused on the area of the lake where the water enters, known on the map as Honker Bay. We also took readings a ways down in deeper water for comparison's sake. Visually, the lake looked in bad shape. The water was a murky green that glimmered with particulate matter that swirled around the boat as we went by. In the Honker Bay region where we focused our testing, there were reeds bathed in algae that coated the surface of the lake in thick, swirling patterns. Surprisingly enough, however, our test results didn't reveal any extreme levels of phosphorous or nitrogen. They were slightly higher than usual, but not by any significant amount. The levels we found were high enough to stimulate plant and algae growth and promote eutrophication, but not enough to do any severe damage. After a briefing with a

  19. Estimation of the algal-available phosphorus pool in sediments of a large, shallow eutrophic lake (Taihu, China) using profiled SMT fractional analysis

    International Nuclear Information System (INIS)

    Zhu Mengyuan; Zhu Guangwei; Li Wei; Zhang Yunlin; Zhao Linlin; Gu Zhao

    2013-01-01

    Because large, shallow lakes are heavily influenced by wind–wave disturbance, it is difficult to estimate internal phosphorus load using traditional methods. To estimate the potential contribution of phosphorus from sediment to overlying water in eutrophic Lake Taihu, phosphorus fractions of surface and deep layer sediments were quantified and analyzed for algal bloom potential using a Standard Measurements and Testing (SMT) sequential extraction method and incubation experiments. Phosphorus bound to Fe, Al and Mn oxides and hydroxides (Fe–P) and organic phosphorus (OP) were to be found bioactive. The difference in Fe–P and OP contents between surface and deep layers equates to the sediment pool of potentially algal-available phosphorus. This pool was estimated at 5168 tons for the entire lake and was closely related to pollution input and algal blooms. Profiled SMT fractionation analysis is thus a potentially useful tool for estimating internal phosphorus loading in large, shallow lakes. - Highlights: ► We used profiled sediment P activity by SMT fractionation to evaluate the P release potential in large and shallow lakes. ► We built the relationship between sediment SMT fractionations of P and the P release by algal bloom degradation process. ► We discussed the supporting mechanism of sediment P release to Microcystis algal bloom in a large and shallow lake. ► We discussed the nutrient control strategy of algal bloom in shallow lakes in highly human activities disturbance catchment. - Profiled SMT fractional analysis of internal phosphorus pool in large, shallow lake.

  20. High net CO2 and CH4 release at a eutrophic shallow lake on a formerly drained fen

    Science.gov (United States)

    Franz, Daniela; Koebsch, Franziska; Larmanou, Eric; Augustin, Jürgen; Sachs, Torsten

    2016-05-01

    Drained peatlands often act as carbon dioxide (CO2) hotspots. Raising the groundwater table is expected to reduce their CO2 contribution to the atmosphere and revitalise their function as carbon (C) sink in the long term. Without strict water management rewetting often results in partial flooding and the formation of spatially heterogeneous, nutrient-rich shallow lakes. Uncertainties remain as to when the intended effect of rewetting is achieved, as this specific ecosystem type has hardly been investigated in terms of greenhouse gas (GHG) exchange. In most cases of rewetting, methane (CH4) emissions increase under anoxic conditions due to a higher water table and in terms of global warming potential (GWP) outperform the shift towards CO2 uptake, at least in the short term.Based on eddy covariance measurements we studied the ecosystem-atmosphere exchange of CH4 and CO2 at a shallow lake situated on a former fen grassland in northeastern Germany. The lake evolved shortly after flooding, 9 years previous to our investigation period. The ecosystem consists of two main surface types: open water (inhabited by submerged and floating vegetation) and emergent vegetation (particularly including the eulittoral zone of the lake, dominated by Typha latifolia). To determine the individual contribution of the two main surface types to the net CO2 and CH4 exchange of the whole lake ecosystem, we combined footprint analysis with CH4 modelling and net ecosystem exchange partitioning.The CH4 and CO2 dynamics were strikingly different between open water and emergent vegetation. Net CH4 emissions from the open water area were around 4-fold higher than from emergent vegetation stands, accounting for 53 and 13 g CH4 m-2 a-1 respectively. In addition, both surface types were net CO2 sources with 158 and 750 g CO2 m-2 a-1 respectively. Unusual meteorological conditions in terms of a warm and dry summer and a mild winter might have facilitated high respiration rates. In sum, even after 9

  1. Large-Scale Mapping and Predictive Modeling of Submerged Aquatic Vegetation in a Shallow Eutrophic Lake

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    Karl E. Havens

    2002-01-01

    Full Text Available A spatially intensive sampling program was developed for mapping the submerged aquatic vegetation (SAV over an area of approximately 20,000 ha in a large, shallow lake in Florida, U.S. The sampling program integrates Geographic Information System (GIS technology with traditional field sampling of SAV and has the capability of producing robust vegetation maps under a wide range of conditions, including high turbidity, variable depth (0 to 2 m, and variable sediment types. Based on sampling carried out in AugustœSeptember 2000, we measured 1,050 to 4,300 ha of vascular SAV species and approximately 14,000 ha of the macroalga Chara spp. The results were similar to those reported in the early 1990s, when the last large-scale SAV sampling occurred. Occurrence of Chara was strongly associated with peat sediments, and maximal depths of occurrence varied between sediment types (mud, sand, rock, and peat. A simple model of Chara occurrence, based only on water depth, had an accuracy of 55%. It predicted occurrence of Chara over large areas where the plant actually was not found. A model based on sediment type and depth had an accuracy of 75% and produced a spatial map very similar to that based on observations. While this approach needs to be validated with independent data in order to test its general utility, we believe it may have application elsewhere. The simple modeling approach could serve as a coarse-scale tool for evaluating effects of water level management on Chara populations.

  2. Large-scale mapping and predictive modeling of submerged aquatic vegetation in a shallow eutrophic lake.

    Science.gov (United States)

    Havens, Karl E; Harwell, Matthew C; Brady, Mark A; Sharfstein, Bruce; East, Therese L; Rodusky, Andrew J; Anson, Daniel; Maki, Ryan P

    2002-04-09

    A spatially intensive sampling program was developed for mapping the submerged aquatic vegetation (SAV) over an area of approximately 20,000 ha in a large, shallow lake in Florida, U.S. The sampling program integrates Geographic Information System (GIS) technology with traditional field sampling of SAV and has the capability of producing robust vegetation maps under a wide range of conditions, including high turbidity, variable depth (0 to 2 m), and variable sediment types. Based on sampling carried out in August-September 2000, we measured 1,050 to 4,300 ha of vascular SAV species and approximately 14,000 ha of the macroalga Chara spp. The results were similar to those reported in the early 1990s, when the last large-scale SAV sampling occurred. Occurrence of Chara was strongly associated with peat sediments, and maximal depths of occurrence varied between sediment types (mud, sand, rock, and peat). A simple model of Chara occurrence, based only on water depth, had an accuracy of 55%. It predicted occurrence of Chara over large areas where the plant actually was not found. A model based on sediment type and depth had an accuracy of 75% and produced a spatial map very similar to that based on observations. While this approach needs to be validated with independent data in order to test its general utility, we believe it may have application elsewhere. The simple modeling approach could serve as a coarse-scale tool for evaluating effects of water level management on Chara populations.

  3. Long-term moderate wind induced sediment resuspension meeting phosphorus demand of phytoplankton in the large shallow eutrophic Lake Taihu.

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    Jian-Ying Chao

    Full Text Available The objective of this study was to investigate the impact of sediment resuspension and phosphorus (P release on phytoplankton growth under different kinds of wind-wave disturbance conditions in the large and shallow eutrophic Lake Taihu in China. Short-term strong wind (STSW conditions, long-term moderate wind (LTMW conditions, and static/calm conditions were investigated. To address this objective, we (1 monitored changes in surface water P composition during field-based sediment resuspension caused by STSW conditions in Lake Taihu, and also conducted (2 a series of laboratory-based sediment resuspension experiments to simulate LTMW and calm conditions. The results showed that under both strong and moderate wind-wave conditions, suspended solids (SS and total phosphorus (TP in the water column increased significantly, but total dissolved phosphorus (TDP and soluble reactive phosphorus (SRP remained low throughout the experiments, indicating that the P released from sediments mainly existed in particulate forms. In STSW conditions, alkaline phosphatase activity (APA and enzymatically hydrolysable phosphorus (EHP increased rapidly, with the peak value occurring following the peak value of wind speed for 1-2 days, and then rapidly decreased after the wind stopped. Under LTMW conditions, APA and EHP increased steadily, and by the end of the laboratory experiments, APA increased by 11 times and EHP increased by 5 times. Chlorophyll a (Chl-a in LTMW conditions increased significantly, but remained low under STSW conditions, demonstrating that the former type of sediment P release promoted phytoplankton growth more effectively, and the latter type did not. Despite the fact that STSW conditions resulted in the release of more TP, TP settled to the bottom rapidly with SS after the wind stopped, and did not promote algal growth. Under LTMW conditions, suspended particulate P was hydrolyzed to SRP by phosphatase and promoted algae growth. Algal growth in

  4. Great cormorant (Phalacrocorax carbo predation on pikeperch (Sander lucioperca L. in shallow eutrophic lakes in Poland

    Directory of Open Access Journals (Sweden)

    Traczuk Piotr

    2017-06-01

    Full Text Available Increases in the population abundance of the piscivorous great cormorant (Phalacrocorax carbo has led to conflicts with fisheries. Cormorants are blamed for decreased fish catches in many lakes in Poland. The aim of this paper is to describe to role of pikeperch (Sander lucioperca in the diet of cormorants nesting in a colony on the island in Lake Warnołty. Since the breeding colony is located in the vicinity of Lake OEniardwy, the largest lake in Poland, the cormorants use the resources in this lake. In 2009-2016, 18,432 regurgitated fish were collected, of which 593 were pikeperch. The share of pikeperch among fish collected in 2009-2012 did not exceed 2%, but from 2013 this increased substantially to maximum of 38.2% in 2015. The smallest pikeperch had a standard length of 8.4 cm, and the largest 42.5 cm. Pikeperch mean length differed by year, and the length distribution was close to normal. The sizes of the regurgitated pikeperch indicate that cormorants prey almost exclusively on juvenile specimens. The results of the present study indicate that cormorant predation has a significant impact on pikeperch populations in lakes in the vicinity of the colony, and the great cormorants are possibly a significant factor in the effectiveness of pikeperch management. When planning for the management of fish populations in lakes subjected to cormorant predation pressure, it should be borne in mind that predation by this piscivorous bird species impacts the abundance and size-age structure of fish populations.

  5. Temporal and spatial variations in kinetics of alkaline phosphatase in sediments of a shallow Chinese eutrophic lake (Lake Donghu).

    Science.gov (United States)

    Yiyong, Zhou; Jianqiu, Li; Min, Zhang

    2002-04-01

    Monthly sediment and interstitial water samples were collected in a shallow Chinese freshwater lake (Lake Donghu) from three areas to determine if alkaline phosphatase activity (APA) plays an important role, in phosphorus cycling in sediment. The seasonal variability in the kinetics of APA and other relevant parameters were investigated from 1995-1996. The phosphatase hydrolyzable phosphorus (PHP) fluctuated seasonally in interstitial water, peaking in the spring. A synchronous pattern was observed in chlorophyll a contents in surface water in general. The orthophosphate (o-P) concentrations in the interstitial water increased during the spring. An expected negative relationship between PHP and Vmax of APA is not evident in interstitial water. The most striking feature of the two variables is their co-occurring, which can be explained in terms of an induction mechanism. It is argued that phosphatase activity mainly contributes to the driving force of o-P regeneration from PHP in interstitial water, supporting the development of phytoplankton biomass in spring. The Vmax values in sediment increased during the summer, in conjunction with lower Km values in interstitial water that suggest a higher affinity for the substrate. The accumulation of organic matter in the sediment could be traced back to the breakdown of the algal spring bloom, which may stimulate APA with higher kinetic efficiency, by a combination of the higher Vmax in sediments plus lower Km values in interstitial water, in summer. In summary, a focus on phosphatase and its substrate in annual scale may provide a useful framework for the development of novel P cycling, possible explanations for the absence of a clear relationship between PHP and APA were PHP released from the sediment which induced APA, and the presence of kinetically higher APA both in sediment and interstitial water which permitted summer mineralization of organic matter derived from the spring bloom to occur. The study highlighted the

  6. Detection of extracellular phosphatases in natural spring phytoplankton of a shallow eutrophic lake (Donghu, China)

    Czech Academy of Sciences Publication Activity Database

    Cao, X.; Štrojsová, Alena; Znachor, Petr; Zapomělová, Eliška; Liu, G.; Vrba, Jaroslav; Zhou, Y.

    2005-01-01

    Roč. 40, č. 3 (2005), s. 251-258 ISSN 0967-0262. [International symposium on river and lake environments /12./. Wuhan, 01.11.2004-12.11.2004] R&D Projects: GA AV ČR(CZ) IAA6017202; GA MŠk(CZ) ME 617 Grant - others:Chinese Academy of Sciences(CN) KZCX1-SW-12-II-02-02; National Science Foundation(CN) 39170165, 39670149, 20177033, 2002CB412300 Institutional research plan: CEZ:AV0Z60170517 Keywords : enzyme labelled fluorescence * phosphatase activity * phytoplankton Subject RIV: EH - Ecology, Behaviour Impact factor: 2.064, year: 2005

  7. Role of organic phosphorus in sediment in a shallow eutrophic lake

    Science.gov (United States)

    Shinohara, Ryuichiro; Hiroki, Mikiya; Kohzu, Ayato; Imai, Akio; Inoue, Tetsunori; Furusato, Eiichi; Komatsu, Kazuhiro; Satou, Takayuki; Tomioka, Noriko; Shimotori, Koichi; Miura, Shingo

    2017-08-01

    We tested the hypothesis that mineralization of molybdenum unreactive phosphorus (MUP) in pore water is the major pathway for the changes in the concentration of molybdenum-reactive P (MRP) in pore water and inorganic P in sediment particles. The concentration of inorganic P in the sediment particles increased from December to April in Lake Kasumigaura, whereas concentrations of organic P in the sediment particles and MUP in pore water decreased. These results suggest that MUP mineralization plays a key role as the source of MRP, whereas desorption of inorganic P from the sediment particles into the pore water is a minor process. One-dimensional numerical simulation of sediment particles and the pore water supported the hypothesis. Diffusive flux of MUP was small in pore water, even in near-surface layers, so mineralization was the dominant process for changing the MUP concentration in the pore water. For MRP, diffusion was the dominant process in the surface layer, whereas adsorption onto the sediment was the dominant process in deeper layers. Researchers usually ignore organic P in the sediment, but organic P in sediment particles and the pore water is a key source of inorganic P in the sediment particles and pore water; our results suggest that in Lake Kasumigaura, organic P in the sediment is an important source, even at depths more than 1 cm below the sediment surface. In contrast, the large molecular size of MUP in pore water hampers diffusion of MUP from the sediment into the overlying water.

  8. Phototaxis of Propsilocerus akamusi (Diptera: Chironomidae) From a Shallow Eutrophic Lake in Response to Led Lamps.

    Science.gov (United States)

    Hirabayashi, Kimio; Nagai, Yoshinari; Mushya, Tetsuya; Higashino, Makoto; Taniguchi, Yoshio

    2017-06-01

    A study on the attraction of adult Propsilocerus akamusi midges to different-colored light traps was carried out from October 21 to November 15, 2013. The 6 colored lights used in light-emitting diode (LED) lamps were white, green, red, blue, amber, and ultraviolet (UV). The UV lamp attracted the most P. akamusi, followed by green, white, blue, amber, and red. A white pulsed LED light attracted only half the number of midges as did a continuous-emission white LED light. The result indicated that manipulation of light color, considering that the red LED light and/or pulsed LED light are not as attractive as the other colors, may be appropriate for the development of an overall integrated strategy to control nuisance P. akamusi in the Lake Suwa area.

  9. Pyrosequencing analysis of free-living and attached bacterial communities in Meiliang Bay, Lake Taihu, a large eutrophic shallow lake in China.

    Science.gov (United States)

    Tang, Xiangming; Li, Linlin; Shao, Keqiang; Wang, Boweng; Cai, Xianlei; Zhang, Lei; Chao, Jianying; Gao, Guang

    2015-01-01

    To elucidate the relationship between particle-attached (PA, ≥ 5.0 μm) and free-living (FL, 0.2-5.0 μm) bacterial communities, samplings were collected seasonally from November 2011 to August 2012 in Meiliang Bay, Lake Taihu, China. We used 454 pyrosequencing of 16S rRNA genes to study bacterial diversity and structure of PA and FL communities. The analysis rendered 37,985 highly qualified reads, subsequently assigned to 1755 operational taxonomic units (97% similarity) for the 8 samples. Although 27 high-level taxonomic groups were obtained, the 3 dominant phyla (Proteobacteria, Actinobacteria, and Bacteroidetes) comprised about 75.9% and 82.4% of the PA and FL fractions, respectively. Overall, we found no significant differences between community types, as indicated by ANOSIM R statistics (R = 0.063, P > 0.05) and the Parsimony test (P = 0.222). Dynamics of bacterial communities were correlated with changes in concentrations of total suspended solids (TSS) and total phosphorus (TP). In summer, a significant taxonomic overlap in the 2 size fractions was observed when Cyanobacteria, a major contributor of TSS and TP, dominated in the water, highlighting the potential rapid exchange between PA and FL bacterial populations in large shallow eutrophic lakes.

  10. Characterization of Phosphate Solubilizing Bacteria in Sediments from a Shallow Eutrophic Lake and a Wetland: Isolation, Molecular Identification and Phosphorus Release Ability Determination

    Directory of Open Access Journals (Sweden)

    Jie Tang

    2010-11-01

    Full Text Available The transformation of phosphorus (P is a major factor of lake eutrophication, and phosphate releasing bacteria play an important role in the release process. Experiments were conducted to investigate P content and characterize phosphate solubilizing bacterial composition at the molecular level in a shallow eutrophic lake and a wetland. Results showed that P concentrations were relatively high and derived from agricultural runoff and domestic or industrial pollution. Enumeration and molecular identification of these strains indicated that these bacterial groups were abundant in the ecosystem and various kinds of bacteria participated in the phosphorus release process. Twelve phosphate solubilizing bacteria, including eight organic P-solubilizing bacteria (OPBs and four inorganic P-solubilizing bacteria (IPBs, which belonged to three different families, were isolated and identified. Cupriavidus basilensis was found for the first time to have the ability to mineralize organic P (OP. Laboratory tests on P release ability revealed that IPBs were more effective at releasing P than OPBs. The most efficient IPB strain could accumulate over 170 mg·L-1 orthophosphate, while the equivalent OPB strain only liberated less than 4 mg·L-1 orthophosphate in liquid culture. The results obtained from this investigation should help clarify the roles of microorganisms in aquatic systems and the mechanisms of eutrophication.

  11. Eutrophication of Lake Waters in China: Cost, Causes, and Control

    Science.gov (United States)

    Le, C.; Zha, Y.; Li, Y.; Sun, D.; Lu, H.; Yin, B.

    2010-04-01

    Lake water eutrophication has become one of the most important factors impeding sustainable economic development in China. Knowledge of the current status of lake water eutrophicatoin and determination of its mechanism are prerequisites to devising a sound solution to the problem. Based on reviewing the literature, this paper elaborates on the evolutional process and current state of shallow inland lake water eutrophication in China. The mechanism of lake water eutrophication is explored from nutrient sources. In light of the identified mechanism strategies are proposed to control and tackle lake water eutrophication. This review reveals that water eutrophication in most lakes was initiated in the 1980s when the national economy underwent rapid development. At present, the problem of water eutrophication is still serious, with frequent occurrence of damaging algal blooms, which have disrupted the normal supply of drinking water in shore cities. Each destructive bloom caused a direct economic loss valued at billions of yuan. Nonpoint pollution sources, namely, waste discharge from agricultural fields and nutrients released from floor deposits, are identified as the two major sources of nitrogen and phosphorus. Therefore, all control and rehabilitation measures of lake water eutrophication should target these nutrient sources. Biological measures are recommended to rehabilitate eutrophied lake waters and restore the lake ecosystem in order to bring the problem under control.

  12. Effects of climate change on bioaccumulation and biomagnification of polycyclic aromatic hydrocarbons in the planktonic food web of a subtropical shallow eutrophic lake in China.

    Science.gov (United States)

    Tao, Yuqiang; Xue, Bin; Lei, Guoliang; Liu, Fei; Wang, Zhen

    2017-04-01

    To date effects of climate change on bioaccumulation and biomagnification of chemical pollutants in planktonic food webs have rarely been studied. Recruitments of plankton have shifted earlier due to global warming. Global warming and precipitation patterns are projected to shift seasonally. Whether and how the shifts in plankton phenology induced by climate change will impact bioaccumulation and biomagnification of chemical pollutants, and how they will respond to climate change are largely unknown. Here, we combine data analysis of the past seven decades, high temporal resolution monitoring and model development to test this hypothesis with nine polycyclic aromatic hydrocarbons (PAHs) in the planktonic food web of a subtropical shallow eutrophic lake in China. We find biphasic correlations between both bioconcentration factors and bioaccumulation factors of the PAHs and the mean temperature, which depend on the recruitment temperatures of cyanobacteria, and copepods and cladocerans. The positive correlations between bioconcentration factors, bioaccumulation factors and the mean temperature will be observed less than approximately 13-18 days by 2050-2060 due to the shifts in plankton phenology. The PAHs and their bioaccumulation and biomagnification will respond seasonally and differently to climate change. Bioaccumulation of most of the PAHs will decrease with global warming, with higher decreasing rates appearing in winter and spring. Biomagnification of most of the PAHs from phytoplankton to zooplankton will increase with global warming, with higher increasing rates appearing in winter and spring. Our study provides novel insights into bioaccumulation and biomagnification of chemical pollutants in eutrophic waters under climate change scenarios. Copyright © 2017 Elsevier Ltd. All rights reserved.

  13. Activity and food choice of piscivorous perch ( Perca fluviatilis ) in a eutrophic shallow lake: a radio-telemetry study

    DEFF Research Database (Denmark)

    Jacobsen, Lene; Berg, Søren; Broberg, M.

    2002-01-01

    in midsummer. The general lack of activity at night supports the idea that perch is a visually oriented forager. 4. There was no significant relationship between daytime activity during the year and temperature or day length, but nighttime activity was correlated with temperature. In contrast with previous......+ planktivorous fish in lakes and has potential implications for pelagic food web structure and lake management by biomanipulation...

  14. Dynamics of chromophoric dissolved organic matter influenced by hydrological conditions in a large, shallow, and eutrophic lake in China.

    Science.gov (United States)

    Zhou, Yongqiang; Zhang, Yunlin; Shi, Kun; Liu, Xiaohan; Niu, Cheng

    2015-09-01

    High concentrations of chromophoric dissolved organic matter (CDOM) are terrestrially derived from upstream tributaries to Lake Taihu, China, and are influenced by hydrological conditions of the upstream watershed. To investigate how the dynamics of CDOM in Lake Taihu are influenced by upstream inflow runoff, four sampling cruises, differing in hydrological conditions, were undertaken in the lake and its three major tributaries, rivers Yincun, Dapu, and Changdou. CDOM absorption, fluorescence spectroscopy, chemical oxygen demand (COD), and stable isotope δ(13)C and δ(15)N measurements were conducted to characterize the dynamics of CDOM. The mean absorption coefficient a(350) collected from the three river profiles (5.15 ± 1.92 m(-1)) was significantly higher than that of the lake (2.95 ± 1.88 m(-1)), indicating that the upstream rivers carried a substantial load of CDOM to the lake. This finding was substantiated by the exclusively terrestrial signal exhibited by the level of δ(13)C (-26.23 ± 0.49‰) of CDOM samples collected from the rivers. Mean a(350) and COD in Lake Taihu were significantly higher in the wet season than in the dry season (t test, p CDOM in the lake is strongly influenced by hydrological conditions of the watershed. Four components were identified by parallel factor analysis, including two protein-like components (C1 and C2), a terrestrial humic-like component (C3), and a microbial humic-like (C4) component. The contribution percentage of the two humic-like components relative to the summed fluorescence intensity of the four components (C humic) increased significantly from the dry to the wet season. This seasonal difference in contribution further substantiated that an enhanced rainfall followed by an elevated inflow runoff in the lake watershed in the wet season may result in an increase in humic-like substances being discharged into the lake compared to that in the dry season. This finding was further supported by an

  15. Environmental Degradation in a Eutrophic Shallow Lake is not Simply Due to Abundance of Non-native Cyprinus carpio

    Science.gov (United States)

    Ramírez-Herrejón, Juan P.; Mercado-Silva, Norman; Balart, Eduardo F.; Moncayo-Estrada, Rodrigo; Mar-Silva, Valentín; Caraveo-Patiño, Javier

    2015-09-01

    Non-native species are often major drivers of the deterioration of natural ecosystems. The common carp Cyprinus carpio are known to cause major changes in lentic systems, but may not be solely responsible for large scale changes in these ecosystems. We used data from extensive collection efforts to gain insight into the importance of carp as drivers of ecosystem change in Lake Patzcuaro, Mexico. We compared the structure (fish density, biomass, diversity, and evenness) of fish assemblages from six Lake Patzcuaro sites with different habitat characteristics. Intersite comparisons were carried out for both wet and dry seasons. We explored the relationships between non-carp species and carp; and studied multivariate interactions between fish abundance and habitat characteristics. From a biomass perspective, carp was dominant in only four of six sites. In terms of density, carp was not a dominant species in all sites. Further, carp density and biomass were not negatively related to native species density and biomass, even when carp density and biomass were positively correlated to water turbidity levels. Carp dominated fish assemblages in the shallowest sites with the highest water turbidity, plant detritus at the bottom, and floating macrophytes covering the lake surface. These results suggest that the effect of carp on fish assemblages may be highly dependent on habitat characteristics in Lake Patzcuaro. Watershed degradation, pollution, water level loss, and other sources of anthropogenic influence may be more important drivers of Lake Patzcuaro degradation than the abundance of carp.

  16. Historical records of polycyclic aromatic hydrocarbon deposition in a shallow eutrophic lake: Impacts of sources and sedimentological conditions.

    Science.gov (United States)

    Li, Chaocan; Huo, Shouliang; Yu, Zhiqiang; Guo, Wei; Xi, Beidou; He, Zhuoshi; Zeng, Xiangying; Wu, Fengchang

    2016-03-01

    Sediment core samples collected from Lake Chaohu were analyzed for 15 priority polycyclic aromatic hydrocarbons (PAHs) to assess the spatial and temporal distributions of the PAHs during lacustrine sedimentary processes and regional economic development. Assessing the PAH sedimentary records over an approximately 100-year time span, we identified two stages in the PAH inputs and sources (before the 1970s and after the 1970s) in the eastern lake region near a village, whereas three stages (before the 1950s, 1950s-1990s and after the 1990s) were identified in the western lake region near urban and industrial areas. Rapid increases in the PAH depositional fluxes occurred during the second stage due to increased human activities in the Lake Chaohu basin. The composition and isomeric ratios of the PAHs revealed that pyrolysis is the main source of PAHs in this lake. Strong positive relationships between PAH concentration and the total organic carbon concentration, sediment grain size (energy consumption and the levels of urban industrialization and civilization, affect both the composition and abundance of the PAHs. Copyright © 2015. Published by Elsevier B.V.

  17. Environmental Degradation in a Eutrophic Shallow Lake is not Simply Due to Abundance of Non-native Cyprinus carpio.

    Science.gov (United States)

    Ramírez-Herrejón, Juan P; Mercado-Silva, Norman; Balart, Eduardo F; Moncayo-Estrada, Rodrigo; Mar-Silva, Valentín; Caraveo-Patiño, Javier

    2015-09-01

    Non-native species are often major drivers of the deterioration of natural ecosystems. The common carp Cyprinus carpio are known to cause major changes in lentic systems, but may not be solely responsible for large scale changes in these ecosystems. We used data from extensive collection efforts to gain insight into the importance of carp as drivers of ecosystem change in Lake Patzcuaro, Mexico. We compared the structure (fish density, biomass, diversity, and evenness) of fish assemblages from six Lake Patzcuaro sites with different habitat characteristics. Intersite comparisons were carried out for both wet and dry seasons. We explored the relationships between non-carp species and carp; and studied multivariate interactions between fish abundance and habitat characteristics. From a biomass perspective, carp was dominant in only four of six sites. In terms of density, carp was not a dominant species in all sites. Further, carp density and biomass were not negatively related to native species density and biomass, even when carp density and biomass were positively correlated to water turbidity levels. Carp dominated fish assemblages in the shallowest sites with the highest water turbidity, plant detritus at the bottom, and floating macrophytes covering the lake surface. These results suggest that the effect of carp on fish assemblages may be highly dependent on habitat characteristics in Lake Patzcuaro. Watershed degradation, pollution, water level loss, and other sources of anthropogenic influence may be more important drivers of Lake Patzcuaro degradation than the abundance of carp.

  18. Extracellular phosphatases produced by phytoplankton and other sources in shallow eutrophic lakes (Wuhan, China): taxon-specific versus bulk activity

    Czech Academy of Sciences Publication Activity Database

    Cao, X.; Song, C.; Zhou, Y.; Štrojsová, A.; Znachor, Petr; Zapomělová, Eliška; Vrba, Jaroslav

    2009-01-01

    Roč. 10, č. 2 (2009), s. 95-104 ISSN 1439-8621 R&D Projects: GA AV ČR(CZ) IAA6017202; GA MŠk(CZ) ME 617 Institutional research plan: CEZ:AV0Z60170517 Keywords : ELF97 phosphate * phosphorus regeneration * polymictic lakes * algae * protozoa Subject RIV: EH - Ecology, Behaviour Impact factor: 0.968, year: 2009

  19. Assessing the Utility of Hydrogen, Carbon and Nitrogen Stable Isotopes in Estimating Consumer Allochthony in Two Shallow Eutrophic Lakes.

    Directory of Open Access Journals (Sweden)

    Jari Syväranta

    Full Text Available Hydrogen stable isotopes (δ2H have recently been used to complement δ13C and δ15N in food web studies due to their potentially greater power to separate sources of organic matter in aquatic food webs. However, uncertainties remain regarding the use of δ2H, since little is known about the potential variation in the amount of exchangeable hydrogen (Hex among common sample materials or the patterns of δ2H when entire food webs are considered. We assessed differences in Hex among the typical sample materials in freshwater studies and used δ2H, δ13C and δ15N to compare their effectiveness in tracing allochthonous matter in food webs of two small temperate lakes. Our results showed higher average amounts of Hex in animal tissues (27% in fish and macroinvertebrates, 19% in zooplankton compared to most plant material (15% in terrestrial plants and 8% in seston/periphyton, with the exception of aquatic vascular plants (23%, referred to as macrophytes. The amount of Hex correlated strongly with sample lipid content (inferred from C:N ratios in fish and zooplankton samples. Overall, the three isotopes provided good separation of sources (seston, periphyton, macrophytes and allochthonous organic matter, particularly the δ2H followed by δ13C. Aquatic macrophytes revealed unexpectedly high δ2H values, having more elevated δ2H values than terrestrial organic matter with direct implications for estimating consumer allochthony. Organic matter from macrophytes significantly contributed to the food webs in both lakes highlighting the need to include macrophytes as a potential source when using stable isotopes to estimate trophic structures and contributions from allochthonous sources.

  20. Laboratory assessment of bioleaching of shallow eutrophic sediment by immobilized photosynthetic bacteria.

    Science.gov (United States)

    Sun, Shiyong; Fan, Shenglan; Shen, Kexuan; Lin, Shen; Nie, Xiaoqin; Liu, Mingxue; Dong, Faqin; Li, Jian

    2017-10-01

    Eutrophic sediment is a serious problem in ecosystem restoration, especially in shallow lake ecosystems. We present a novel bioleaching approach to treat shallow eutrophic sediment with the objective of preventing the release of nitrate, phosphate, and organic compounds from the sediment to the water column, using porous mineral-immobilized photosynthetic bacteria (PSB). Bioactivity of bacteria was maintained during the immobilization process. Immobilized PSB beads were directly deposited on the sediment surface. The deposited PSB utilized pollutants diffused from the sediment as a nutritive matrix for growth. We evaluated the effects of light condition, temperature, initial pH, amount of PSB beads, and frequency of addition of PSB beads for contaminant removal efficiency during bioleaching operations. The presented study indicated that immobilized PSB beads using porous minerals as substrates have considerable application potential in bioremediation of shallow eutrophic lakes.

  1. Eutrophication potential of Payette Lake, Idaho

    Science.gov (United States)

    Woods, Paul F.

    1997-01-01

    Payette Lake was studied during water years 1995-96 to determine the 20.5-square-kilometer lake's assimilative capacity for nutrients and, thus, its eutrophication potential. The study included quantification of hydrologic and nutrient budgets, characterization of water quality in the limnetic and littoral zones, development of an empirical nutrient load/lake response model, and estimation of the limnological effects of a large-scale forest fire in the lake's 373-square-kilometer watershed during the autumn of 1994. Streamflow from the North Fork Payette River, the lake's primary tributary, delivered about 73 percent of the lake's inflow over the 2 years. Outflow from the lake, measured since 1908, was 128 and 148 percent of the long-term average in 1995 and 1996, respectively. The larger volumes of outflow reduced the long-term average water-

  2. Dissolved organic carbon and its potential predictors in eutrophic lakes.

    Science.gov (United States)

    Toming, Kaire; Kutser, Tiit; Tuvikene, Lea; Viik, Malle; Nõges, Tiina

    2016-10-01

    Understanding of the true role of lakes in the global carbon cycle requires reliable estimates of dissolved organic carbon (DOC) and there is a strong need to develop remote sensing methods for mapping lake carbon content at larger regional and global scales. Part of DOC is optically inactive. Therefore, lake DOC content cannot be mapped directly. The objectives of the current study were to estimate the relationships of DOC and other water and environmental variables in order to find the best proxy for remote sensing mapping of lake DOC. The Boosted Regression Trees approach was used to clarify in which relative proportions different water and environmental variables determine DOC. In a studied large and shallow eutrophic lake the concentrations of DOC and coloured dissolved organic matter (CDOM) were rather high while the seasonal and interannual variability of DOC concentrations was small. The relationships between DOC and other water and environmental variables varied seasonally and interannually and it was challenging to find proxies for describing seasonal cycle of DOC. Chlorophyll a (Chl a), total suspended matter and Secchi depth were correlated with DOC and therefore are possible proxies for remote sensing of seasonal changes of DOC in ice free period, while for long term interannual changes transparency-related variables are relevant as DOC proxies. CDOM did not appear to be a good predictor of the seasonality of DOC concentration in Lake Võrtsjärv since the CDOM-DOC coupling varied seasonally. However, combining the data from Võrtsjärv with the published data from six other eutrophic lakes in the world showed that CDOM was the most powerful predictor of DOC and can be used in remote sensing of DOC concentrations in eutrophic lakes. Copyright © 2016 Elsevier Ltd. All rights reserved.

  3. Clearing lakes : an ecosystem approach to the restoration and management of shallow lakes in the Netherlands

    NARCIS (Netherlands)

    Hosper, H.

    1997-01-01

    In the 1950 s and 1960 s, most shallow lakes in the Netherlands shifted from macrophyte-dominated clear water lakes, towards algae-dominated turbid water lakes. Eutrophication, i.e. increased nutrient loading, is the main cause of the deterioration

  4. From Greenland to green lakes: Cultural eutrophication and the loss of benthic pathways in lakes

    DEFF Research Database (Denmark)

    Vadeboncoeur, Y.; Jeppesen, E.; Zanden, M. J. V.

    2003-01-01

    Benthic community responses to lake eutrophication are poorly understood relative to pelagic responses. We compared phytoplankton and periphyton productivity along a eutrophication gradient in Greenland, U.S., and Danish lakes. Phytoplankton productivity increased along the phosphorus gradient (t...

  5. Eutrophication monitoring for Lake Superior's Chequamegon ...

    Science.gov (United States)

    A priority for the Lake Superior CSMI was to identify susceptible nearshore eutrophication areas. We developed an integrated sampling design to collect baseline data for Lake Superior’s Chequamegon Bay to understand how nearshore physical processes and tributary loading relate to observed chlorophyll concentrations. Sampling included ship-based water samples combined with vertical CTD casts, continuous in situ towing and data collected from an autonomous underwater glider. Sampling was conducted during June, July and September. The glider collected regional data as part of three extended missions in Lake Superior over the same periods. During the study, two significant storm events impacted the western end of Lake Superior; the first occurred during July 11-12, with 8-10 inches of rain in 24hrs, and the second on July 21 with winds in excess of 161 km/h. Using GIS software, we organized these diverse temporal data sets along a continuous time line with temporally coincident Modis Satellite data to visualize surface sediment plumes in relation to water quality measurements. Preliminary results suggest that both events impacted regional water quality, and that nearshore physical forces (upwelling and currents) influenced the spatial variability. Results comparing in situ measures with remotely sensed images will be discussed. not applicable

  6. Effect of eutrophication on the distribution of arsenic species in eutrophic and mesotrophic lakes

    Energy Technology Data Exchange (ETDEWEB)

    Hasegawa, H. [Graduate School of Natural Science and Technology, Kanazawa University, Kakuma, Kanazawa 920-1192 (Japan)], E-mail: hhiroshi@t.kanazawa-u.ac.jp; Rahman, M. Azizur; Matsuda, T.; Kitahara, T.; Maki, T.; Ueda, K. [Graduate School of Natural Science and Technology, Kanazawa University, Kakuma, Kanazawa 920-1192 (Japan)

    2009-02-01

    Effects of eutrophication on arsenic speciation were studied in eutrophic Lake Kiba and mesotrophic Lake Biwa, Japan. By combining hydride generation atomic absorption spectrometry with ultraviolet irradiation, inorganic, methyl and ultraviolet-labile fractions of arsenic were determined. In both Lakes, inorganic species (As(V + III)) dominated over other forms of arsenic all the year round. Most of methylarsenic fraction was dimethylarsinic acid (DMAA), and the concentration of monomethylarsonic acid (MMAA) was below the detection limit. Measurements of size-fractioned arsenic concentrations in water column indicate that most of the DMAA was distributed in truly dissolved fraction (< 10 kDa), while ultraviolet-labile fractions were distributed in particulate (> 0.45 {mu}m) and colloidal (10 kDa-0.45 {mu}m) fractions. Arsenic speciation in eutrophic Lake Kiba fluctuated greatly with season. The ultraviolet-labile fractions were observed with the increase of DMAA from May to October, and they disappeared with the decrease of DMAA in January. In mesotrophic Lake Biwa, the ultraviolet-labile fractions of arsenic were not influenced as much as those in eutrophic Lake Kiba. On the other hand DMAA concentration was higher in Lake Biwa compared to that in Lake Kiba. The results suggest that the biosynthesis of complex organoarsenicals was enhanced by eutrophication, and the arsenic speciation would be influenced by the balance of biological processes in natural waters.

  7. Food-web studies in shallow eutrophic lakes by the Netherlands Institute of Ecology: Main results, knowledge gaps and new perspectives

    NARCIS (Netherlands)

    Vijverberg, J.; Gulati, R.D.; Mooij, W.M.

    1993-01-01

    For more than 20 years scientists of the ‘Food-chain studies’ Group of the former Limnological Institute have been studying interactions within the pelagic food web. Purpose of research was to explain the structure and dynamics of the zooplankton and fish communities in lakes and reservoirs in

  8. Dynamics of cyanobacterial bloom formation during short-term hydrodynamic fluctuation in a large shallow, eutrophic, and wind-exposed Lake Taihu, China.

    Science.gov (United States)

    Wu, Tingfeng; Qin, Boqiang; Zhu, Guangwei; Luo, Liancong; Ding, Yanqing; Bian, Geya

    2013-12-01

    Short-term hydrodynamic fluctuations caused by extreme weather events are expected to increase worldwide because of global climate change, and such fluctuations can strongly influence cyanobacterial blooms. In this study, the cyanobacterial bloom disappearance and reappearance in Lake Taihu, China, in response to short-term hydrodynamic fluctuations, was investigated by field sampling, long-term ecological records, high-frequency sensors and MODIS satellite images. The horizontal drift caused by the dominant easterly wind during the phytoplankton growth season was mainly responsible for cyanobacterial biomass accumulation in the western and northern regions of the lake and subsequent bloom formation over relatively long time scales. The cyanobacterial bloom changed slowly under calm or gentle wind conditions. In contrast, the short-term bloom events within a day were mainly caused by entrainment and disentrainment of cyanobacterial colonies by wind-induced hydrodynamics. Observation of a westerly event in Lake Taihu revealed that when the 30 min mean wind speed (flow speed) exceeded the threshold value of 6 m/s (5.7 cm/s), cyanobacteria in colonies were entrained by the wind-induced hydrodynamics. Subsequently, the vertical migration of cyanobacterial colonies was controlled by hydrodynamics, resulting in thorough mixing of algal biomass throughout the water depth and the eventual disappearance of surface blooms. Moreover, the intense mixing can also increase the chance for forming larger and more cyanobacterial colonies, namely, aggregation. Subsequently, when the hydrodynamics became weak, the cyanobacterial colonies continuously float upward without effective buoyancy regulation, and cause cyanobacterial bloom explosive expansion after the westerly. Furthermore, the results of this study indicate that the strong wind happening frequently during April and October can be an important cause of the formation and expansion of cyanobacterial blooms in Lake Taihu.

  9. [Lake eutrophication modeling in considering climatic factors change: a review].

    Science.gov (United States)

    Su, Jie-Qiong; Wang, Xuan; Yang, Zhi-Feng

    2012-11-01

    Climatic factors are considered as the key factors affecting the trophic status and its process in most lakes. Under the background of global climate change, to incorporate the variations of climatic factors into lake eutrophication models could provide solid technical support for the analysis of the trophic evolution trend of lake and the decision-making of lake environment management. This paper analyzed the effects of climatic factors such as air temperature, precipitation, sunlight, and atmosphere on lake eutrophication, and summarized the research results about the lake eutrophication modeling in considering in considering climatic factors change, including the modeling based on statistical analysis, ecological dynamic analysis, system analysis, and intelligent algorithm. The prospective approaches to improve the accuracy of lake eutrophication modeling with the consideration of climatic factors change were put forward, including 1) to strengthen the analysis of the mechanisms related to the effects of climatic factors change on lake trophic status, 2) to identify the appropriate simulation models to generate several scenarios under proper temporal and spatial scales and resolutions, and 3) to integrate the climatic factors change simulation, hydrodynamic model, ecological simulation, and intelligent algorithm into a general modeling system to achieve an accurate prediction of lake eutrophication under climatic change.

  10. Hulun Lake's ecological health and evaluation of its' eutrophication

    Science.gov (United States)

    Li, W.; Yang, W.; Wang, X.; Huang, J.; Sun, B.; Li, X.

    2013-12-01

    Hulun Lake is the largest lake in the north of china. The special geological location determines its important position in regional environmental protection. In terms of Hulun Lake's current situation, this paper chooses the indexes of lake system, lake structure and lake condition. Based on the calculation of these indexes and related theory , the evaluation standards of Hulun Lake's ecological healthy system are worked out. The author used Analytic Hierarchy Process to determine the weight of each indicator layer and criteria layer, and then applied fuzzy-pattern recognition model to calculate, finally, identifying the status of Hulun Lake according to the degrees of all levels. At the same time, the author used an integrated nutrition state index method to do the eutrophication assessment. Evaluation results show that the current status of Hulun Lake is healthy and it is in the moderate level of eutrophication.

  11. A comparison between benthic gillnet and bottom trawl for assessing fish assemblages in a shallow eutrophic lake near the Changjiang River estuary

    Science.gov (United States)

    Li, Yalei; Liu, Qigen; Chen, Liping; Zhao, Liangjie; Wu, Hao; Chen, Liqiao; Hu, Zhongjun

    2018-03-01

    Two fishing methods including gillnetting and trawling to estimate attributes of fish assemblage were compared in Dianshan Lake from August 2009 to July 2010. Species composition differed significantly between the gears, with four significant contributors in gillnet catches and one in trawl catches. Trawling collected more proportions of benthic species by number and biomass than gillnetting. Size distribution was significantly influenced by fishing technique; gillnetting captured relatively less small-sized fishes and trawling captured less large-sized individuals. Trawling produced species richness closer to the one expected than gillnetting. On the whole, trawl catch was a quadratic polynomial function of gillnet catch and a significantly negative correlation was found between them, both of which varied as different polynomial functions of temperature. However, trawl and gillnet catches were significantly correlated only in one of five month groups. It is concluded that single-gear-based surveys can be misleading in assessments of attributes of fish assemblages, bottom trawling is a more effective gear for assessing fish diversity than benthic gillnetting, and using gillnet catches as an indicator of fish density depends on fishing season in the lake.

  12. Tissue distributions and seasonal dynamics of the hepatotoxic microcystins-LR and -RR in a freshwater snail (Bellamya aeruginosa) from a large shallow, eutrophic lake of the subtropical China

    International Nuclear Information System (INIS)

    Chen Jun; Xie Ping; Guo Longgen; Zheng Li; Ni Leyi

    2005-01-01

    Tissue distributions and seasonal dynamics of the hepatotoxic microcystins-LR and -RR in a freshwater snail (Bellamya aeruginosa) were studied monthly in a large shallow, eutrophic lake of the subtropical China during June-November, 2003. Microcystins (MCs) were quantitatively determined by High-Performance Liquid Chromatography (HPLC) with a qualitative analysis by a Finnigan LC-MS system. On the average of the study period, hepatopancreas was the highest in MC contents (mean 4.14 and range 1.06-7.42 μg g -1 DW), followed by digestive tracts (mean 1.69 and range 0.8-4.54 μg g -1 DW) and gonad (mean 0.715 and range 0-2.62 μg g -1 DW), whereas foot was the least (mean 0.01 and range 0-0.06 μg g -1 DW). There was a positive correlation in MC contents between digestive tracts and hepatopancreas. A constantly higher MC content in hepatopancreas than in digestive tracts indicates a substantial bioaccumulation of MCs in the hepatopancreas of the snail. The average ratio of MC-LR/MC-RR showed a steady increase from digestive tracts (0.44) to hepatopancreas (0.63) and to gonad (0.96), suggesting that MC-LR was more resistant to degradation in the snail. Since most MCs were present in the hepatopancreas, digestive tracts and gonad with only a very small amount in the edible foot, the risk to human health may not be significant if these toxic parts are removed prior to snail consumption. However, the possible transference of toxins along food chains should not be a negligible concern. - Snails bioaccumulate microcystins in their hepatopancreas, gut and gonad, posing a risk to human consumers

  13. Preliminary Data on Eutrophication of Carstic Lakes

    OpenAIRE

    , B. Hoxha; , F. Cane; , M. Avdolli; , A. Dauti

    2016-01-01

    Nutrients play an important role in the health and functioning of aquatic ecosystems. However, an excess of nutrients, particularly phosphorous and nitrogen compounds, can lead to adverse effects on both ecology and uses of receiving waters. This process accelerated by human activities is termed cultural eutrophication, and is recognized as a significant environmental problem. The purpose of this paper is to represent some preliminary data on eutrophication of water bodies from a chemical poi...

  14. Alcian blue-stained particles in a eutrophic lake

    DEFF Research Database (Denmark)

    Worm, J.; Søndergaard, Morten

    1998-01-01

    We used a neutral solution of Alcian Blue to stain transparent particles in eutrophic Lake Frederiksborg Slotss0, Denmark. Alcian Blue-stained particles (ABSP) appeared to be similar to the so-called transparent exopolymer particles (TEP) identified with an acidic solution of Alcian Blue. Our...

  15. Algal Diet of Small-Bodied Crustacean Zooplankton in a Cyanobacteria-Dominated Eutrophic Lake.

    Directory of Open Access Journals (Sweden)

    Ilmar Tõnno

    Full Text Available Small-bodied cladocerans and cyclopoid copepods are becoming increasingly dominant over large crustacean zooplankton in eutrophic waters where they often coexist with cyanobacterial blooms. However, relatively little is known about their algal diet preferences. We studied grazing selectivity of small crustaceans (the cyclopoid copepods Mesocyclops leuckarti, Thermocyclops oithonoides, Cyclops kolensis, and the cladocerans Daphnia cucullata, Chydorus sphaericus, Bosmina spp. by liquid chromatographic analyses of phytoplankton marker pigments in the shallow, highly eutrophic Lake Võrtsjärv (Estonia during a seasonal cycle. Copepods (mainly C. kolensis preferably consumed cryptophytes (identified by the marker pigment alloxanthin in gut contents during colder periods, while they preferred small non-filamentous diatoms and green algae (identified mainly by diatoxanthin and lutein, respectively from May to September. All studied cladoceran species showed highest selectivity towards colonial cyanobacteria (identified by canthaxanthin. For small C. sphaericus, commonly occuring in the pelagic zone of eutrophic lakes, colonial cyanobacteria can be their major food source, supporting their coexistence with cyanobacterial blooms. Pigments characteristic of filamentous cyanobacteria and diatoms (zeaxanthin and fucoxanthin, respectively, algae dominating in Võrtsjärv, were also found in the grazers' diet but were generally avoided by the crustaceans commonly dominating the zooplankton assemblage. Together these results suggest that the co-occurring small-bodied cyclopoid and cladoceran species have markedly different algal diets and that the cladocera represent the main trophic link transferring cyanobacterial carbon to the food web in a highly eutrophic lake.

  16. Acidity removal from Lusatian mining lakes through eutrophication

    Energy Technology Data Exchange (ETDEWEB)

    Fyson, A.; Nixdorf, B.; Steinberg, C.F.W. [Brandenburg University of Technology, Cottbus (Germany)

    2001-07-01

    The flooded, disused lignite pits of Lusatia in north-eastern Germany are characterised by low pH (2 - 3.5) and high concentrations of iron which contribute to high acidity. Removal of acidity from these lakes using low-cost, environmentally acceptable technologies is being investigated. One option is the enhancement of biologically mediated, alkalinity generating processes, through controlled eutrophication to sustainably increase nutrient cycling and carbon inputs. Although the primary production of these waters is potentially high and diverse algae grow in these lakes, the growth of autotrophic organisms is usually limited by extremely low concentrations of P and inorganic C. Theoretical considerations and laboratory mesocosm results are used to demonstrate the potential productivity of these acid waters and the direct and indirect role of controlled eutrophication in removing acidity. Such data are being used to generate self-sustaining, environmentally friendly, affordable remediation strategies to develop these lakes for recreation and wildlife. 14 refs., 1 tab.

  17. Could Methane Oxidation in Lakes Be Enhanced by Eutrophication?

    Science.gov (United States)

    Van Grinsven, S.; Villanueva, L.; Harrison, J.; S Sinninghe Damsté, J.

    2017-12-01

    Climate change and eutrophication both affect aquatic ecosystems. Eutrophication is caused by high nutrient inputs, leading to algal blooms, oxygen depletion and disturbances of the natural balances in aquatic systems. Methane, a potent greenhouse gas produced biologically by anaerobic degradation of organic matter, is often released from the sediments of lakes and marine systems to overlying water and the atmosphere. Methane oxidation, a microbial methane consumption process, can limit methane emission from lakes and reservoirs by 50-80%. Here, we studied methane oxidation in a seasonally stratified reservoir: Lacamas Lake in Washington, USA. We found this lake has a large summer storage capacity of methane in its deep water layer, with a very active microbial community capable of oxidizing exceptionally high amounts of methane. The natural presence of terminal electron acceptors is, however, too low to support these high potential rates. Addition of eutrophication-related nutrients such as nitrate and sulfate increased the methane removal rates by 4 to 7-fold. The microbial community was studied using 16S rRNA gene amplicon sequencing and preliminary results indicate the presence of a relatively unknown facultative anaerobic methane oxidizer of the genus Methylomonas, capable of using nitrate as an electron donor. Experiments in which anoxic and oxic conditions were rapidly interchanged showed this facultative anaerobic methane oxidizer has an impressive flexibility towards large, rapid changes in environmental conditions and this feature might be key to the unexpectedly high methane removal rates in eutrophied and anoxic watersheds.

  18. Lake Baikal Ecosystem Faces the Threat of Eutrophication

    Directory of Open Access Journals (Sweden)

    Galina I. Kobanova

    2016-01-01

    Full Text Available Recently there have been reports about large accumulations of algae on the beaches of Lake Baikal, the oldest and deepest freshwater body on earth, near major population centers and in areas with large concentrations of tourists and tourism infrastructure. To evaluate the observations indicating the ongoing process of eutrophication of Lake Baikal, a field study in July 2012 in the two largest bays of Lake Baikal, Barguzinsky and Chivyrkuisky, was organized. The study of phytoplankton using the sedimentary method and quantitative records of accumulations of macrophytes in the surf zone was made. In Chivyrkuisky Bay, we found the massive growth of colorless flagellates and cryptomonads as well as the aggregations of Elodea canadensis along the sandy shoreline (up to 26 kg/m2. Barguzinsky Bay registered abundantly cyanobacterial Anabaena species, cryptomonads, and extremely high biomass of Spirogyra species (up to 70 kg/m3. The results show the presence of local but significant eutrophication of investigated bays. To prevent further extensions of this process in unique ecosystem of Lake Baikal, the detailed study and monitoring of the coastal zone, the identification of the sources of eutrophication, and the development of measures to reduce nutrient inputs in the waters are urgently needed.

  19. Eutrophication status and control strategy of Taihu Lake

    Institute of Scientific and Technical Information of China (English)

    Limin ZHANG; Minfang XIA; Lei ZHANG; Chun WANG; Jilai LU

    2008-01-01

    The water quality and eutrophication status of Taihu Lake in recent years are presented and the pollution trends are analyzed. It is shown that because of unreas-onable industrial structures, pollution discharge per GDP is high within the Taihu basin, and the pollution discharge from point and-non-point sources exceed the basin's environmental carrying capacity. Especially, excessive pollutants containing nitrgogen and phosphorus are being discharged. Moreover, eutrophication may also result from internal pollution sources such as the release of nutrient elements from sediment. All these factors have resulted in-the water quality deterioration of Taihu Lake. To solve this environmental problem, possible con-trol strategies are summarized, including the control of internal pollution sources and inflow-river pollution, eco-logical restoration and reconstruction of the degraded lakeside zone ecosystem, clean water diversion, dredging, and manual algae removal.

  20. Estimating the critical phosphorus loading of shallow lakes with the ecosystem model PCLake: Sensitivity, calibration and uncertainty

    NARCIS (Netherlands)

    Janse, J.H.; Scheffer, M.; Lijklema, L.; Van Liere, L.; Sloot, J.S.; Mooij, W.M.

    2010-01-01

    There is a vast body of knowledge that eutrophication of lakes may cause algal blooms. Among lakes, shallow lakes are peculiar systems in that they typically can be in one of two contrasting (equilibrium) states that are self-stabilizing: a ‘clear’ state with submerged macrophytes or a ‘turbid’

  1. Estimating the critical phosphorus loading of shallow lakes with the ecosystem model PCLake: Sensitivity, calibration and uncertainty

    NARCIS (Netherlands)

    Janse, J.H.; Scheffer, M.; Lijklema, L.; Liere, van L.; Sloot, J.S.; Mooij, W.M.

    2010-01-01

    There is avast body of knowledge that eutrophication of lakes may cause algal blooms. Among lakes, shallow lakes are peculiar systems in that they typically can be in one of two contrasting (equilibrium) states that are self-stabilizing: a 'clear' state with submerged macrophytes or a 'turbid' state

  2. Cascading trophic interactions in the littoral zone: an enclosure experiment in shallow Lake Stigsholm, Denmark

    DEFF Research Database (Denmark)

    Jeppesen, E.; Søndergaard, M.; Søndergaard, M.

    2002-01-01

    The importance of grazer versus resource control has been extensively studied in the pelagic zone of lakes. In contrast, comparatively little is known about trophic interactions within the littoral zone. We conducted an experiment in the littoral zone of a eutrophic shallow lake using six 20 m2......, zooplankton grazing was equivalent to production in M+, but amounted to littoral zones do not alone feed on particles produced in the water, but also exploit alternative sources such as periphyton...... hypothesize that the strong cascading effects of zooplankton on chlorophyll-a and microorganisms in the littoral zone at natural fish densities are restricted to eutrophic lakes with high plant densities....

  3. Restoration of Eutrophic Lakes with Fluctuating Water Levels: A 20-Year Monitoring Study of Two Inter-Connected Lakes

    Directory of Open Access Journals (Sweden)

    Meryem Beklioğlu

    2017-02-01

    Full Text Available Eutrophication continues to be the most important problem preventing a favorable environmental state and detrimentally impacting the ecosystem services of lakes. The current study describes the results of analyses of 20 year monitoring data from two interconnected Anatolian lakes, Lakes Mogan and Eymir, receiving sewage effluents and undergoing restoration. The first step of restoration in both lakes was sewage effluent diversion. Additionally, in hypertrophic Lake Eymir, biomanipulation was conducted, involving removal of benthi-planktivorous fish and prohibition of pike fishing. The monitoring period included high (H and low (L water levels (WL enabling elucidation of the effects of hydrological changes on lake restoration. In shallower Lake Mogan, macrophyte abundance increased after the sewage effluent diversion in periods with low water levels even at turbid water. In comparatively deeper Lake Eymir, the first biomanipulation led to a clear water state with abundant macrophyte coverage. However, shortly after biomanipulation, the water clarity declined, coinciding with low water level (LWL periods during which nutrient concentrations increased. A second biomanipulation was conducted, mostly during high water level (HWL period, resulting in a major decrease in nutrient concentrations and clearer water, but without an expansion of macrophytes. We conclude that repetitive fish removal may induce recovery but its success may be confounded by high availability of nutrients and adverse hydrological conditions.

  4. Modeling Diel Oxygen Dynamics and Ecosystem Metabolism in a Shallow, Eutrophic Estuary

    Science.gov (United States)

    Weeks Bay is a shallow eutrophic estuary that exhibits frequent summertime diel-cycling hypoxia and periods of dissolved oxygen (DO) oversaturation during the day. Diel DO dynamics in shallow estuaries like Weeks Bay are complex, and may be influenced by wind forcing, vertical an...

  5. Watershed vs. within-lake drivers of nitrogen: phosphorus dynamics in shallow lakes.

    Science.gov (United States)

    Ginger, Luke J; Zimmer, Kyle D; Herwig, Brian R; Hanson, Mark A; Hobbs, William O; Small, Gaston E; Cotner, James B

    2017-10-01

    Research on lake eutrophication often identifies variables affecting amounts of phosphorus (P) and nitrogen (N) in lakes, but understanding factors influencing N:P ratios is important given its influence on species composition and toxin production by cyanobacteria. We sampled 80 shallow lakes in Minnesota (USA) for three years to assess effects of watershed size, proportion of watershed as both row crop and natural area, fish biomass, and lake alternative state (turbid vs. clear) on total N : total P (TN : TP), ammonium, total dissolved phosphorus (TDP), and seston stoichiometry. We also examined N:P stoichiometry in 20 additional lakes that shifted states during the study. Last, we assessed the importance of denitrification by measuring denitrification rates in sediment cores from a subset of 34 lakes, and by measuring seston δ 15 N in four additional experimental lakes before and after they were experimentally manipulated from turbid to clear states. Results showed alternative state had the largest influence on overall N:P stoichiometry in these systems, as it had the strongest relationship with TN : TP, seston C:N:P, ammonium, and TDP. Turbid lakes had higher N at given levels of P than clear lakes, with TN and ammonium 2-fold and 1.4-fold higher in turbid lakes, respectively. In lakes that shifted states, TN was 3-fold higher in turbid lakes, while TP was only 2-fold higher, supporting the notion N is more responsive to state shifts than is P. Seston δ 15 N increased after lakes shifted to clear states, suggesting higher denitrification rates may be important for reducing N levels in clear states, and potential denitrification rates in sediment cores were among the highest recorded in the literature. Overall, our results indicate lake state was a primary driver of N:P dynamics in shallow lakes, and lakes in clear states had much lower N at a given level of P relative to turbid lakes, likely due to higher denitrification rates. Shallow lakes are often

  6. Prediction of Chl-a concentrations in an eutrophic lake using ANN models with hybrid inputs

    Science.gov (United States)

    Aksoy, A.; Yuzugullu, O.

    2017-12-01

    Chlorophyll-a (Chl-a) concentrations in water bodies exhibit both spatial and temporal variations. As a result, frequent sampling is required with higher number of samples. This motivates the use of remote sensing as a monitoring tool. Yet, prediction performances of models that convert radiance values into Chl-a concentrations can be poor in shallow lakes. In this study, Chl-a concentrations in Lake Eymir, a shallow eutrophic lake in Ankara (Turkey), are determined using artificial neural network (ANN) models that use hybrid inputs composed of water quality and meteorological data as well as remotely sensed radiance values to improve prediction performance. Following a screening based on multi-collinearity and principal component analysis (PCA), dissolved-oxygen concentration (DO), pH, turbidity, and humidity were selected among several parameters as the constituents of the hybrid input dataset. Radiance values were obtained from QuickBird-2 satellite. Conversion of the hybrid input into Chl-a concentrations were studied for two different periods in the lake. ANN models were successful in predicting Chl-a concentrations. Yet, prediction performance declined for low Chl-a concentrations in the lake. In general, models with hybrid inputs were superior over the ones that solely used remotely sensed data.

  7. Differences in the exploitation of bream in three shallow lake systems and their relation to water quality

    NARCIS (Netherlands)

    Lammens, E.H.R.R.; Nes, van E.H.; Mooij, W.M.

    2002-01-01

    1. The development of bream populations, water transparency, chlorophyll-a concentration, extent of submerged vegetation and densities of the zebra mussel, Dreissena polymorpha, were analysed in three shallow eutrophic lake systems subject to different fish management. 2. In Lake Veluwemeer, the

  8. Differences in the exploitation of bream in three shallow lake systems and their relation to water quality

    NARCIS (Netherlands)

    Lammens, E.H.R.R.; Van Nes, E.H.; Mooij, W.M.

    2002-01-01

    SUMMARY1. The development of bream populations, water transparency, chlorophyll-a concentration, extent of submerged vegetation and densities of the zebra mussel, Dreissena polymorpha, were analysed in three shallow eutrophic lake systems subject to different fish management. 2. In Lake Veluwemeer,

  9. Legacy effects of nitrogen and phosphorus in a eutrophic lake catchment: Slapton Ley, SW England

    Science.gov (United States)

    Burt, T. P.; Worrall, F.; Howden, N. J. K.

    2017-12-01

    Slapton Ley is a freshwater coastal lagoon in SW England. The Ley is part of a National Nature Reserve, which is divided into two basins: the Higher Ley (39 ha) is mainly reed swamp; the Lower Ley (77 ha) is a shallow lake (maximum depth 2.9 m). In the 1960s it became apparent that the Lower Ley was becoming increasingly eutrophic. In order to gauge water, sediment and nutrient inputs into the lake, measurements began on the main catchments in 1969. Continuous monitoring of discharge and a weekly water-sampling programme have been maintained by the Slapton Ley Field Centre ever since. The monitoring programme has been supplemented by a number of research projects which have sought to identify the salient hydrological processes operating within the Slapton catchments and to relate these to the delivery of sediment and solute to the stream system. Long-term monitoring data are also available for the catchment area including the lake from the Environment Agency.The nitrate issue has been of particular interest at Slapton; although many longer series exist for large river basins like the Thames, the long record of nitrate data for the Slapton catchments is unique in Britain for a small rural basin. Recent declines in nitrate concentration may reflect less intensive agricultural activity, lower fertiliser inputs in particular, but there may also be a legacy effect in the shallow groundwater system. Phosphorus concentrations in stream and lake water have also shown declining concentrations but a phosphorus legacy in the surficial lake sediments means that algal blooms continue to develop in most summers, as indicated by a continued rise in summer pH levels. Further field observation at the sediment-water interface is needed to better understand the biogeochemical drivers and the balance between N and P limitation in the lake. Successful management of the Nature Reserve requires better understanding of the links between hydrological and biogeochemical processes operating

  10. The National Eutrophication Survey: lake characteristics and historical nutrient concentrations

    Directory of Open Access Journals (Sweden)

    J. Stachelek

    2018-01-01

    Full Text Available Historical ecological surveys serve as a baseline and provide context for contemporary research, yet many of these records are not preserved in a way that ensures their long-term usability. The National Eutrophication Survey (NES database is currently only available as scans of the original reports (PDF files with no embedded character information. This limits its searchability, machine readability, and the ability of current and future scientists to systematically evaluate its contents. The NES data were collected by the US Environmental Protection Agency between 1972 and 1975 as part of an effort to investigate eutrophication in freshwater lakes and reservoirs. Although several studies have manually transcribed small portions of the database in support of specific studies, there have been no systematic attempts to transcribe and preserve the database in its entirety. Here we use a combination of automated optical character recognition and manual quality assurance procedures to make these data available for analysis. The performance of the optical character recognition protocol was found to be linked to variation in the quality (clarity of the original documents. For each of the four archival scanned reports, our quality assurance protocol found an error rate between 5.9 and 17 %. The goal of our approach was to strike a balance between efficiency and data quality by combining entry of data by hand with digital transcription technologies. The finished database contains information on the physical characteristics, hydrology, and water quality of about 800 lakes in the contiguous US (Stachelek et al.(2017, https://doi.org/10.5063/F1639MVD. Ultimately, this database could be combined with more recent studies to generate meta-analyses of water quality trends and spatial variation across the continental US.

  11. The National Eutrophication Survey: lake characteristics and historical nutrient concentrations

    Science.gov (United States)

    Stachelek, Joseph; Ford, Chanse; Kincaid, Dustin; King, Katelyn; Miller, Heather; Nagelkirk, Ryan

    2018-01-01

    Historical ecological surveys serve as a baseline and provide context for contemporary research, yet many of these records are not preserved in a way that ensures their long-term usability. The National Eutrophication Survey (NES) database is currently only available as scans of the original reports (PDF files) with no embedded character information. This limits its searchability, machine readability, and the ability of current and future scientists to systematically evaluate its contents. The NES data were collected by the US Environmental Protection Agency between 1972 and 1975 as part of an effort to investigate eutrophication in freshwater lakes and reservoirs. Although several studies have manually transcribed small portions of the database in support of specific studies, there have been no systematic attempts to transcribe and preserve the database in its entirety. Here we use a combination of automated optical character recognition and manual quality assurance procedures to make these data available for analysis. The performance of the optical character recognition protocol was found to be linked to variation in the quality (clarity) of the original documents. For each of the four archival scanned reports, our quality assurance protocol found an error rate between 5.9 and 17 %. The goal of our approach was to strike a balance between efficiency and data quality by combining entry of data by hand with digital transcription technologies. The finished database contains information on the physical characteristics, hydrology, and water quality of about 800 lakes in the contiguous US (Stachelek et al.(2017), https://doi.org/10.5063/F1639MVD). Ultimately, this database could be combined with more recent studies to generate meta-analyses of water quality trends and spatial variation across the continental US.

  12. Benthic-planktonic coupling, regime shifts, and whole-lake primary production in shallow lakes.

    Science.gov (United States)

    Genkai-Kato, Motomi; Vadeboncoeur, Yvonne; Liboriussen, Lone; Jeppesen, Erik

    2012-03-01

    Alternative stable states in shallow lakes are typically characterized by submerged macrophyte (clear-water state) or phytoplankton (turbid state) dominance. However, a clear-water state may occur in eutrophic lakes even when macrophytes are absent. To test whether sediment algae could cause a regime shift in the absence of macrophytes, we developed a model of benthic (periphyton) and planktonic (phytoplankton) primary production using parameters derived from a shallow macrophyte-free lake that shifted from a turbid to a clear-water state following fish removal (biomanipulation). The model includes a negative feedback effect of periphyton on phosphorus (P) release from sediments. This in turn induces a positive feedback between phytoplankton production and P release. Scenarios incorporating a gradient of external P loading rates revealed that (1) periphyton and phytoplankton both contributed substantially to whole-lake production over a broad range of external P loading in a clear-water state; (2) during the clear-water state, the loss of benthic production was gradually replaced by phytoplankton production, leaving whole-lake production largely unchanged; (3) the responses of lakes to biomanipulation and increased external P loading were both dependent on lake morphometry; and (4) the capacity of periphyton to buffer the effects of increased external P loading and maintain a clear-water state was highly sensitive to relationships between light availability at the sediment surface and the of P release. Our model suggests a mechanism for the persistence of alternative states in shallow macrophyte-free lakes and demonstrates that regime shifts may trigger profound changes in ecosystem structure and function.

  13. Editorial - A critical perspective on geo-engineering for eutrophication management in lakes

    NARCIS (Netherlands)

    Lurling, Miguel; Mackay, Eleanor; Reitzel, Kasper; Spears, Bryan M.

    2016-01-01

    Eutrophication is the primary worldwide water quality issue. Reducing excessive external nutrient loading is the most straightforward action in mitigating eutrophication, but lakes, ponds and reservoirs often show little, if any, signs of recovery in the years following external load reduction.

  14. Management of eutrophication in Lake De Kuil (The Netherlands) using combined flocculant - lanthanum modified bentonite treatment

    NARCIS (Netherlands)

    Waaijen, G.; Oosterhout, van F.; Douglas, G.C.; Lurling, M.F.L.L.W.

    2016-01-01

    Eutrophication of Lake De Kuil (The Netherlands, 6.7 ha, maximum depth 9 m) has frequently caused cyanobacterial blooms resulting in swimming bans or the issue of water quality warnings during summer. The eutrophication was mainly driven by sediment phosphorus (P)-release. The external P-loading was

  15. Eutrophication, Nile perch and food-web interactions in south-east Lake Victoria

    NARCIS (Netherlands)

    Cornelissen, I.J.M.

    2015-01-01

    The increasing eutrophication, the introduction of Nile perch (Lates niloticus) and the increasing fishing pressure has changed Lake Victoria tremendously the last century. Since the 1960s, eutrophication increased primary production, enabling an increase in fish production. However,

  16. A Remote Sensing Approach to Estimate Vertical Profile Classes of Phytoplankton in a Eutrophic Lake

    Directory of Open Access Journals (Sweden)

    Kun Xue

    2015-10-01

    Full Text Available The extension and frequency of algal blooms in surface waters can be monitored using remote sensing techniques, yet knowledge of their vertical distribution is fundamental to determine total phytoplankton biomass and understanding temporal variability of surface conditions and the underwater light field. However, different vertical distribution classes of phytoplankton may occur in complex inland lakes. Identification of the vertical profile classes of phytoplankton becomes the key and first step to estimate its vertical profile. The vertical distribution profile of phytoplankton is based on a weighted integral of reflected light from all depths and is difficult to determine by reflectance data alone. In this study, four Chla vertical profile classes (vertically uniform, Gaussian, exponential and hyperbolic were found to occur in three in situ vertical surveys (28 May, 19–24 July and 10–12 October in a shallow eutrophic lake, Lake Chaohu. We developed and validated a classification and regression tree (CART to determine vertical phytoplankton biomass profile classes. This was based on an algal bloom index (Normalized Difference algal Bloom Index, NDBI applied to both in situ remote sensing reflectance (Rrs and MODIS Rayleigh-corrected reflectance (Rrc data in combination with data of local wind speed. The results show the potential of retrieving Chla vertical profiles information from integrated information sources following a decision tree approach.

  17. Specific activity and concentration model applied to 137Cs movement in a eutrophic lake

    International Nuclear Information System (INIS)

    Vanderploeg, H.A.; Booth, R.S.; Clark, F.H.

    1976-01-01

    A linear systems-analysis model which simulates time-dependent dynamics of specific activity and concentration of radiocesium in lake ecosystems was applied to a shallow, eutrophic lake that had received a pulse input of 137 Cs. Best estimates of transfer coefficients for abiotic compartments (sediment, interstitial water and lake water) and the macrophyte compartment which controlled the mass balance of cesium in water were determined by ''tuning'' our initial estimates of the transfer coefficients to observed data on 137 Cs concentrations and contents of these compartments. In most cases, the optimized transfer coefficients for the abiotic compartments were not greatly different from our independently derived initial estimates, and the simulations for optimized coefficients were close to those based on initial estimates. The 137 Cs concentrations in water as predicted by the optimized transfer coefficients were then used to calculate 137 Cs kinetics in biota other than macrophytes. In general, model simulations were close to concentrations observed in the biota. The agreement between 137 Cs concentrations and simulations in bottom invertebrates supported our assumption that bottom sediments are not a major source of Cs to the biota. Our specific activity and concentration model was compared to the radionuclide content model, the model used in terrestrial ecosystems. For biotic components of aquatic ecosystems, values of α/sub ij/, the transfer coefficients of our model, are easily estimated from turnover rates of radiocesium in individual organisms in the laboratory

  18. Evidence for the Importance of Atmospheric Nitrogen Deposition to Eutrophic Lake Dianchi, China

    Science.gov (United States)

    Zhan, X.; Bo, Y.; Zhou, F.; Liu, X.; Paerl, H. W.; Shen, J.; Wang, R.; Li, F. R.; Tao, S.; Yanjun, D.; Tang, X.

    2017-12-01

    Elevated atmospheric nitrogen (N) deposition has significantly influenced aquatic ecosystems, especially with regard to their N budgets and phytoplankton growth potentials. Compared to a considerable number of studies on oligotrophic lakes and oceanic waters, little evidence for the importance of N deposition has been generated for eutrophic lakes, even though emphasis has been placed on reducing external N inputs to control eutrophication in these lakes. Our high-resolution observations of atmospheric depositions and riverine inputs of biologically reactive N species into eutrophic Lake Dianchi (the sixth largest freshwater lake in China) shed new light onto the contribution of N deposition to total N loads. Annual N deposition accounted for 15.7% to 16.6% of total N loads under variable precipitation conditions, 2-fold higher than previous estimates (7.6%) for the Lake Dianchi. The proportion of N deposition to total N loads further increased to 27-48% in May and June when toxic blooms of the ubiquitous non-N2 fixing cyanobacteria Microcystis spp. are initiated and proliferate. Our observations reveal that reduced N (59%) contributes a greater amount than oxidized N to total N deposition, reaching 56-83% from late spring to summer. Progress toward mitigating eutrophication in Lake Dianchi and other bloom-impacted eutrophic lakes will be difficult without reductions in ammonia emissions and subsequent N deposition.

  19. GIS-based pollution hazard mapping and assessment framework of shallow lakes: southeastern Pampean lakes (Argentina) as a case study.

    Science.gov (United States)

    Romanelli, A; Esquius, K S; Massone, H E; Escalante, A H

    2013-08-01

    The assessment of water vulnerability and pollution hazard traditionally places particular emphasis on the study on groundwaters more than on surface waters. Consequently, a GIS-based Lake Pollution Hazard Index (LPHI) was proposed for assessing and mapping the potential pollution hazard for shallow lakes due to the interaction between the Potential Pollutant Load and the Lake Vulnerability. It includes easily measurable and commonly used parameters: land cover, terrain slope and direction, and soil media. Three shallow lake ecosystems of the southeastern Pampa Plain (Argentina) were chosen to test the usefulness and applicability of this suggested index. Moreover, anthropogenic and natural medium influence on biophysical parameters in these three ecosystems was examined. The evaluation of the LPHI map shows for La Brava and Los Padres lakes the highest pollution hazard (≈30 % with high to very high category) while Nahuel Rucá Lake seems to be the less hazardous water body (just 9.33 % with high LPHI). The increase in LPHI value is attributed to a different loading of pollutants governed by land cover category and/or the exposure to high slopes and influence of slope direction. Dissolved oxygen and biochemical oxygen demand values indicate a moderately polluted and eutrophized condition of shallow lake waters, mainly related to moderate agricultural activities and/or cattle production. Obtained information by means of LPHI calculation result useful to perform a local diagnosis of the potential pollution hazard to a freshwater ecosystem in order to implement basic guidelines to improve lake sustainability.

  20. Critical phosphorus loading of different types of shallow lakes and the consequences for management estimated with the ecosystem model PCLake

    NARCIS (Netherlands)

    Janse, J.H.; De Senerpont Domis, L.N.; Scheffer, M.; Lijklema, L.; Klinge, M.; Mooij, W.M.; Van Liere, L.

    2008-01-01

    Shallow lakes typically can be in one of two contrasting states: a clear state with submerged macrophytes or a turbid state dominated by phytoplankton. Eutrophication may cause a switch from the clear to the turbid state, if the phosphorus loading exceeds a critical value. Recovery of the clear

  1. Disentangling the effects of a century of eutrophication and climate warming on freshwater lake fish assemblages.

    Directory of Open Access Journals (Sweden)

    Peter C Jacobson

    Full Text Available Eutrophication and climate warming are profoundly affecting fish in many freshwater lakes. Understanding the specific effects of these stressors is critical for development of effective adaptation and remediation strategies for conserving fish populations in a changing environment. Ecological niche models that incorporated the individual effects of nutrient concentration and climate were developed for 25 species of fish sampled in standard gillnet surveys from 1,577 Minnesota lakes. Lake phosphorus concentrations and climates were hindcasted to a pre-disturbance period of 1896-1925 using existing land use models and historical temperature data. Then historical fish assemblages were reconstructed using the ecological niche models. Substantial changes were noted when reconstructed fish assemblages were compared to those from the contemporary period (1981-2010. Disentangling the sometimes opposing, sometimes compounding, effects of eutrophication and climate warming was critical for understanding changes in fish assemblages. Reconstructed abundances of eutrophication-tolerant, warmwater taxa increased in prairie lakes that experienced significant eutrophication and climate warming. Eutrophication-intolerant, warmwater taxa abundance increased in forest lakes where primarily climate warming was the stressor. Coolwater fish declined in abundance in both ecoregions. Large changes in modeled abundance occurred when the effects of both climate and eutrophication operated in the same direction for some species. Conversely, the effects of climate warming and eutrophication operated in opposing directions for other species and dampened net changes in abundance. Quantifying the specific effects of climate and eutrophication will allow water resource managers to better understand how lakes have changed and provide expectations for sustainable fish assemblages in the future.

  2. Evaluating stocking of YOY pike Esox lucius as a tool in the restoration of shallow lakes

    DEFF Research Database (Denmark)

    Skov, Christian; Nilsson, P.A.

    2007-01-01

    from field surveys in eight study lakes stocked with YOY pike as well as from the literature. 3. Our model showed that all parameters studied were important for predicting the effects of pike stocking on cyprinids. In particular, body size at stocking, cyprinid production and pike survival were good...... as an appropriate and reliable tool for restoration programmes in shallow lakes, and indicate that when used efforts should be made to optimize the timing of stocking in relation to YOY cyprinid production and to increase the stocking body size of the pike.......1. Stocking of piscivores in shallow, eutrophicated lakes to reduce cyprinid densities is a common approach in lake restorations. Young-of-the-year (YOY) pike Esox lucius are frequently used to reduce cyprinid densities, but their effectiveness is equivocal. This study uses a simple model to assess...

  3. Controlling Eutrophication in A Mediterranean Shallow Reservoir by Phosphorus Loading Reduction: The Need for an Integrated Management Approach

    Science.gov (United States)

    Zaragüeta, Mikel; Acebes, Pablo

    2017-04-01

    Increased nutrient enrichment in Mediterranean standing waters has enhanced the risk of being affected by cyanobacterial blooms. Because phosphorus abatement is shaped as a crucial strategy for controlling eutrophication, this study introduces a structural thinking, experiential learning laboratory with animation dynamic model elaborated for Cazalegas Reservoir (Spain) to assess the feasibility of implementing a set of internal and external control measures and hydromorphological adjustments to meet the goal of oligotrophication. This shallow reservoir is another case where recurrent eutrophication has led to reach annual mean total phosphorus concentrations (0.16 ± 0.08 mg total phosphorus/L) over the threshold of current water policies, triggering cyanobacterial growth up to undesirable levels in summer time (approximately 50,000 cells/mL). Modeling results showed that (i) after upgrading water treatment in the main tributary, (ii) applying a lanthanum-modified bentonite into the water column and sediment, and (iii) increasing reservoir water level, in-lake P concentrations and cyanobacterial abundance decreased in an 88% (below 0.01 mg total phosphorus/L) and 84% (below 6000 cells/mL), respectively in the most critical periods. However, the constraints of the proposed management strategies are associated with their costs of implementation and the time span for a stable trophic recovery of the reservoir. In that end, integrated management approaches are aimed to be adopted by water managers to reach adequate ecological status of freshwater bodies.

  4. Eutrophication in the Yunnan Plateau lakes: the influence of lake morphology, watershed land use, and socioeconomic factors.

    Science.gov (United States)

    Liu, Wenzhi; Li, Siyue; Bu, Hongmei; Zhang, Quanfa; Liu, Guihua

    2012-03-01

    Lakes play an important role in socioeconomic development and ecological balance in China, but their water quality has deteriorated considerably in recent decades. In this study, we investigated the spatial-temporal variations of eutrophication parameters (secchi depth, total nitrogen, total phosphorus, chemical oxygen demand, chlorophyll-a, trophic level index, and trophic state index) and their relationships with lake morphology, watershed land use, and socioeconomic factors in the Yunnan Plateau lakes. Results indicated that about 77.8% of lakes were eutrophic according to trophic state index. The plateau lakes showed spatial variations in water quality and could be classified into high-nutrient and low-nutrient groups. However, because watersheds were dominated by vegetation, all eutrophication parameters except chlorophyll-a showed no significant differences between the wet and dry seasons. Lake depth, water residence time, volume, and percentage of built-up land were significantly related to several eutrophication parameters. Agricultural land use and social-economic factors had no significant correlation with all eutrophication parameters. Stepwise regression analyses demonstrated that lake depth and water residence time accounted for 73.8% to 87.6% of the spatial variation of single water quality variables, respectively. Redundancy analyses indicated that lake morphology, watershed land use, and socioeconomic factors together explained 74.3% of the spatial variation in overall water quality. The results imply that water quality degradation in the plateau lakes may be mainly due to the domestic and industrial wastewaters. This study will improve our understanding of the determinants of lake water quality and help to design efficient strategies for controlling eutrophication in the plateau region.

  5. Driving forces of the diel distribution of phytoplankton functional groups in a shallow tropical lake (Lake Monte Alegre, Southeast Brazil

    Directory of Open Access Journals (Sweden)

    LM. Rangel

    Full Text Available Phytoplankton vertical and diel dynamics in a small shallow lake (Lake Monte Alegre, Ribeirão Preto, state of São Paulo were investigated in two climatological periods: July 2001 (cool-dry season and March 2002 (warm-rainy season. Monte Alegre is a eutrophic reservoir, with a warm polymictic discontinuous circulation pattern. The lake was thermally stratified in both periods, although dissolved oxygen varied less in the cool-dry period. Phytoplankton biomass was higher in the warm-rainy season and the vertical distribution was stratified in both seasons. Flagellate groups (Lm, Y, W1 and W2 and functional groups typical of shallow eutrophic environments (J, X1 and Sn were important throughout the study period. The lake's thermal pattern strongly influenced the vertical distribution of the phytoplankton community in both periods. Biomass, functional groups and size classes of phytoplankton also were determined by the presence of more efficient herbivores in the lake, especially during the cool-dry period when phytoplankton biomass decreased.

  6. Mercury distribution in the main compartments of the eutrophic Lake Candia (Northern Italy

    Directory of Open Access Journals (Sweden)

    Gian Maria BEONE

    2009-08-01

    Full Text Available Total mercury (T-Hg and organic mercury (mainly methylmercury, MeHg concentrations in the most important compartments (water, sediment, macrophytes, zooplankton, mussels and fish of the shallow and eutrophic Lake Candia (Turin, Northern Italy were measured. The decreasing sequence of the T-Hg concentrations is as follows: cat-fish (143 μg kg-1 d.w., zooplankton (77 μg kg-1 d.w., Unio pictorum mancus (37.9 μg kg-1 d.w., macrophytes (28.9 μg kg-1 d.w.. The content of mercury in mussel tissues increased with the size of the animal, but the relationship between Hg concentration and tissue weight was negative, indicating that the rate of mercury accumulation was lower than the tissue growth rate. The amount of mercury accumulated in the mussels living in the lake sediments was estimated to be 0.54 μg m-2. The importance of mercury biomagnification is also discussed.

  7. Specific activity and concentration model applied to cesium-137 movement in a eutrophic lake

    International Nuclear Information System (INIS)

    Vanderploeg, H.A.; Booth, R.S.; Clark, F.H.

    1975-01-01

    A linear systems-analysis model which simulates time-dependent dynamics of specific activity and concentration of radiocesium in lake ecosystems was applied to a shallow, eutrophic lake that had received a pulse input of 137 Cs. Best estimates of transfer coefficients for abiotic compartments (sediment, interstitial water, and water) and macrophyte compartment which control mass balance of cesium in water were determined by tuning our initial estimates of the transfer coefficients to observed data on 137 Cs concentrations and contents of these compartments. In most cases, the optimized transfer coefficients of the abiotic compartments were not greatly different from our independently-derived initial estimates, and the simulations for optimized coefficients were close to those based on initial estimates. The simulations of 137 Cs concentration in water predicted by the optimized transfer coefficients were used to derive 137 Cs kinetics in biota other than macrophytes. In general, model simulations were close to concentrations observed in the biota. The agreement between 137 Cs concentrations and simulations in bottom invertebrates supported our assumption that bottom sediments are not a major source of Cs to the biota. (U.S.)

  8. The Potential Applications of Real-Time Monitoring of Water Quality in a Large Shallow Lake (Lake Taihu, China) Using a Chromophoric Dissolved Organic Matter Fluorescence Sensor

    OpenAIRE

    Niu, Cheng; Zhang, Yunlin; Zhou, Yongqiang; Shi, Kun; Liu, Xiaohan; Qin, Boqiang

    2014-01-01

    This study presents results from field surveys performed over various seasons in a large, eutrophic, shallow lake (Lake Taihu, China) using an in situ chromophoric dissolved organic matter (CDOM) fluorescence sensor as a surrogate for other water quality parameters. These measurements identified highly significant empirical relationships between CDOM concentration measured using the in situ fluorescence sensor and CDOM absorption, fluorescence, dissolved organic carbon (DOC), chemical oxygen ...

  9. Effects of N and P enrichment on competition between phytoplankton and benthic algae in shallow lakes: a mesocosm study : Environmental Science and Pollution Research

    NARCIS (Netherlands)

    Zhang, Xiufeng; Mei, Xueying; Gulati, Ramesh; Liu, Zhengwen

    2015-01-01

    Competition for resources between coexisting phytoplankton and benthic algae, but with different habitats and roles in functioning of lake ecosystems, profoundly affects dynamics of shallow lakes in the process of eutrophication. An experiment was conducted to test the hypothesis that combined

  10. Sedimentary Record of Cladoceran Functionality under Eutrophication and Re-Oligotrophication in Lake Maggiore, Northern Italy

    Directory of Open Access Journals (Sweden)

    Liisa Nevalainen

    2018-01-01

    Full Text Available We examined fossil Cladocera (Crustacea communities and their functional assemblages in a ~60-year sediment record from Lake Maggiore, northern Italy. Our main objective was to document the response of aquatic community functioning to environmental stress during eutrophication (1960–1985 and recovery (post-1985, and to identify environmental controls on cladoceran functionality. Of the functional groups, large filter feeders and oval epibenthos thrived prior to eutrophication (reference conditions pre-1960 and globular epibenthos and small filter feeders increased during eutrophication and as the lake recovered. Multivariate analyses suggested that bottom-up controls (i.e., total phosphorus were important for shaping functional assemblages but taxonomic community changes were likely related to top-down control by predators, particularly the predaceous cladoceran Bythotrephes longimanus. Functional diversity (FD was higher and Daphnia ephippia length (DEL larger during the reference and early eutrophication periods and decreased during eutrophication and recovery. Both FD (high and DEL (large were distinct during reference period, but were similar (FD low, DEL small between the eutrophication and recovery periods. The functional attributes and the assemblages did not recover post-eutrophication, suggesting that the system exhibited a clear shift to low FD and dominance of small filterers. Cladoceran functionality appears to be related to fundamental ecosystem functions, such as productivity, and may thus provide insights for long-term changes in ecological resilience.

  11. Metal accumulation by submerged macrophytes in eutrophic lakes at the watershed scale.

    Science.gov (United States)

    Xing, Wei; Wu, Haoping; Hao, Beibei; Liu, Guihua

    2013-10-01

    Metal concentrations (Al, Ba, Ca, K, Li, Mg, Na, Se, Sr and Ti) in submerged macrophytes and corresponding water and sediments were studied in 24 eutrophic lakes along the middle and lower reaches of the Yangtze River (China). Results showed that these eutrophic lakes have high metal concentrations in both water and sediments because of human activities. Average concentrations of Al and Na in tissues of submerged macrophytes were very high in sampled eutrophic lakes. By comparison, Ceratophyllum demersum and Najas marina accumulated more metals (e.g. Ba, Ca, K, Mg, Na, Sr and Ti). Strong positive correlations were found between metal concentrations in tissues of submerged macrophytes, probably because of co-accumulation of metals. The concentrations of Li, Mg, Na and Sr in tissues of submerged macrophytes significantly correlated with their corresponding water values, but not sediment values.

  12. An Overview of Sediment Organic Matter Records of Human Eutrophication in the Laurentian Great Lakes Region

    Energy Technology Data Exchange (ETDEWEB)

    Meyers, Philip A. [University of Michigan, Department of Geological Sciences (United States)], E-mail: pameyers@umich.ed

    2006-12-15

    The isotopic and molecular compositions of organic matter buried in lake sediments provide information that helps to reconstruct past environmental conditions and to assess impacts of humans on local ecosystems. This overview of sedimentary records from the North American Great Lakes region describes examples of applications of organic geochemistry to paleolimnological reconstructions. These lakes experienced a succession of human-induced environmental changes that started after completion of the Erie Canal in 1825. Agricultural deforestation in the mid-nineteenth century released soil nutrients that increased algal productivity and caused an associated increase in algal biomarkers in sediment records. Eutrophication that accompanied magnified delivery of municipal nutrients to the lakes in the 1960s and 1970s created excursions to less negative {delta}{sup 13}C values in sediment organic matter. Increased organic carbon mass accumulation rates mirror the isotopic evidence of eutrophication in the Great Lakes.

  13. Improving Multi-Objective Management of Water Quality Tipping Points: Revisiting the Classical Shallow Lake Problem

    Science.gov (United States)

    Quinn, J. D.; Reed, P. M.; Keller, K.

    2015-12-01

    Recent multi-objective extensions of the classical shallow lake problem are useful for exploring the conceptual and computational challenges that emerge when managing irreversible water quality tipping points. Building on this work, we explore a four objective version of the lake problem where a hypothetical town derives economic benefits from polluting a nearby lake, but at the risk of irreversibly tipping the lake into a permanently polluted state. The trophic state of the lake exhibits non-linear threshold dynamics; below some critical phosphorus (P) threshold it is healthy and oligotrophic, but above this threshold it is irreversibly eutrophic. The town must decide how much P to discharge each year, a decision complicated by uncertainty in the natural P inflow to the lake. The shallow lake problem provides a conceptually rich set of dynamics, low computational demands, and a high level of mathematical difficulty. These properties maximize its value for benchmarking the relative merits and limitations of emerging decision support frameworks, such as Direct Policy Search (DPS). Here, we explore the use of DPS as a formal means of developing robust environmental pollution control rules that effectively account for deeply uncertain system states and conflicting objectives. The DPS reformulation of the shallow lake problem shows promise in formalizing pollution control triggers and signposts, while dramatically reducing the computational complexity of the multi-objective pollution control problem. More broadly, the insights from the DPS variant of the shallow lake problem formulated in this study bridge emerging work related to socio-ecological systems management, tipping points, robust decision making, and robust control.

  14. Long term behaviour and seasonal cycling of Cs-137 in a eutrophic lake in Southern Germany

    Energy Technology Data Exchange (ETDEWEB)

    Klemt, E.; Knaus, J.; Putyrskaya, V.; Ries, T. [Hochschule Ravensburg-Weingarten (Germany)

    2014-07-01

    Lake Vorsee is a small and shallow eutrophic lake with a swampy watershed about 25 km north of Lake Constance in southern Germany which is intensely used for fishing by local fishermen. It is completely overgrown by watermilfoil (Myriophyllum spicatum) which produces thick watery organic sediment layers when it decomposes in late autumn and winter. In 1986 the watershed of Lake Vorsee had a Cs-137 Chernobyl inventory of about 30 kBq/m{sup 2}. The Cs-137 activity concentration in the water was monitored for more than 25 years and it can be well described by a sum of two exponential functions superimposed by some seasonal cycling. To analyze the seasonal cycling of the Cs-137 activity concentration in water and in suspended matter, samples were collected with a Large Volume Water Sampler (Midiya-System) on a monthly base and measured gamma-spectrometrically by HPGe-detectors. Also the Cs-137 distribution coefficient kD was determined. Additionally, in the lake water the concentration of the competing ions K{sup +} and NH{sub 4}{sup +} was determined by ion-chromatography, total organic carbon (TOC) with a combustion catalytic oxidation / NDIR detection method as well as the dissolved O{sub 2}-concentration and the pH and temperature of the water by hand-held probes. Information on the amount of precipitation was taken from nearby weather stations. In this project the following hypothesis will be checked: In late autumn the decomposing watermilfoil produces NH{sub 4}{sup +}-ions which exchange Cs{sup +}-ions from their binding places, thereby increasing the Cs-137 activity concentration in the water. In spring the watermilfoil starts growing which leads to a larger O{sub 2}-concentration in the water and helps to disintegrate the NH{sub 4}{sup +}-ions in this way decreasing the Cs-137 concentration again. A possible influence of the other measured parameters on the seasonal cycling will also be discussed. Document available in abstract form only. (authors)

  15. Carbon and nitrogen burial in a plateau lake during eutrophication and phytoplankton blooms.

    Science.gov (United States)

    Huang, Changchun; Zhang, Linlin; Li, Yunmei; Lin, Chen; Huang, Tao; Zhang, Mingli; Zhu, A-Xing; Yang, Hao; Wang, Xiaolei

    2018-03-01

    Organic carbon (OC) buried in lake sediment is an important component of the global carbon cycle. The impact of eutrophication on OC burial in lakes should be addressed due to worldwide lake eutrophication. Fourteen 210 Pb- and 137 Cs-dated sediment cores taken in Dianchi Lake (China) in August 2006 (seven cores) and July 2014 (seven cores) were analyzed to evaluate the response of the organic carbon accumulation rate (OCAR) to eutrophication and algal blooms over the past hundred years. The mean value of OCAR before eutrophication occurred in 1979, 16.62±7.53 (mean value±standard deviation), increased to 54.33±27.29gm -2 yr -1 after eutrophication. It further increased to 61.98±28.94gm -2 yr -1 after algal blooms occurred (1989). The accumulation rate of organic nitrogen (ONAR) is coupled with OCAR. The high loss rate of OC and organic nitrogen (ON) leads to a long-term burial efficiency of only 10% and 5% of OC and ON. However, this efficiency can still lead to an increase in OCAR by a factor of 4.55 during algal blooms in Dianchi Lake. Dianchi Lake stored 1.26±0.32 Tg carbon and 0.071±0.018 Tg nitrogen, including 0.94±0.23 Tg OC and 0.32±0.14 Tg inorganic carbon, 0.066±0.018 Tg ON, 0.002±0.001 Tg nitrate nitrogen (NO 3 -N) and 0.003±0.001 Tg ammonium nitrogen (NH 4 -N) between 1900 and 2012. Copyright © 2017 Elsevier B.V. All rights reserved.

  16. Are bacteria an important food source for rotifers in eutrophic lakes?

    NARCIS (Netherlands)

    Ooms-Wilms, A.L.

    1997-01-01

    In situ grazing measurements using fluorescent particles of 0.5, 2.4 and 6.3 mu m diameter in eutrophic Lake Loosdrecht (The Netherlands) showed that Anuraeopsis fissa, a small rotifer, filtered the smallest, bacteria sized particles as efficiently or more efficiently than the larger particles. In

  17. The evolution of the eutrophication of the Palić Lake (Serbia ...

    African Journals Online (AJOL)

    Due to inadequate water quality, it was dried out in 1971 and re-established ... for treated municipal waste waters coming from the lagoons for active sludge ... eutrophication is the enormous amount of sediment at the bottom of the Palic Lake.

  18. Effect of water chemistry on zooplanktonic and microbial communities across freshwater ecotones in different macrophyte-dominated shallow lakes

    Directory of Open Access Journals (Sweden)

    Tomasz Mieczan

    2015-12-01

    Full Text Available Complex interactions between zooplankton and microbial food webs are vital to the ecosystem ecology of shallow lakes. However, little is known about how horizontal changes in environmental conditions may influence microbial and metazoan communities in shallow lakes. The specific goals of the study were i to describe environmental variables responsible for the distribution of bacteria, flagellates, ciliates and crustaceans in an adjacent canal, ecotone and reservoir (littoral-pelagic zone in two different types of lakes (Ceratophyllum-dominated and Potamogeton-dominated lakes; ii to determine whether the contact zone waters differ in hydrochemical and biological terms from the waters of the canal and the open water zone; iii and to evaluate the influence of particular macro-habitats (canal, canal/reservoir, littoral and pelagic zone on the interactions between components of the planktonic food web. We studied four shallow, eutrophic lakes in Polesie Lubelskie (eastern Poland. The highest diversity and abundance of microorganisms and crustaceans were observed in the canal-reservoir contact zone, while the lowest values were noted in the pelagic zone. Hence, the contact zone in the investigated lakes could fulfil the function of an ecotone, distinguished by a significant increase in biodiversity, abundance, and species specificity of micro- and macroorganisms. Weak relations between food web components were found in the Ceratophyllum-dominated lakes, where environmental variables explained the bulk of the total variance in plankton abundance, whereas in the Potamogeton-dominated lakes, where environmental variables had a minor role in the total variance in plankton abundance, strong predator-prey relations were noted. Spatial structure of habitats proved to be another important factor for relationships between food web components, as our study indicated that habitat complexity can reduce negative correlations between food web components. Our study

  19. Determinants of biodiversity in subtropical shallow lakes (Atlantic coast, Uruguay)

    NARCIS (Netherlands)

    Kruk, C.; Rodriguez-Gallego, L.; Meerhoff, M.; Quintans, F.; Lacerot, G.; Mazzeo, N.; Scasso, F.; Paggi, J.C.; Peeters, E.; Marten, S.

    2009-01-01

    P> Shallow lakes and ponds contribute disproportionally to species richness relative to other aquatic ecosystems. In-lake conditions (e.g. presence of submerged plants) seem to play a key role in determining diversity, as has been demonstrated for temperate lakes. When water quality deteriorates

  20. Recovery of lake vegetation following reduced eutrophication and acidification

    DEFF Research Database (Denmark)

    Båstrup-Spohr, Lars; Sand-Jensen, Kaj; Olesen, Sissel C. H.

    2017-01-01

    in pollution control has been successful in terms of markedly improving water quality of lakes and, with a time lag, macrophyte species richness. Although relatively common species have spread across lakes and resulted in homogenised macrophyte communities, continued efforts to reduce pollution could ensure...

  1. Research into the Eutrophication of an Artificial Playground Lake near the Yangtze River

    Directory of Open Access Journals (Sweden)

    Min Pang

    2018-03-01

    Full Text Available Water pollution in urban rivers is serious in China. Eutrophication and other issues are prominent. Taking the artificial Playground Lake in Zhenjiang as an example, a numerical model combining particle tracing, hydrodynamics, water quality and eutrophication was constructed to simulate the water quality improvement in Playground Lake with or without water diversion by pump and sluice. Simulation results using particle tracking showed that the water residence time depended on wind direction: east wind, 125 h; southeast wind, 115 h; south wind, 95 h. With no water diversion, the lower the flow velocity of Playground Lake under three wind fields, the more serious the eutrophication. Under pump diversion, the water body in Playground Lake can be entirely replaced by water diversion for 30 h. When the temperature is lower than 15 °C, from 15 °C to 25 °C and higher than 25 °C, the water quality can be maintained for 15 d, 10 d and 7 d, respectively. During high tide periods of spring tides in the Yangtze River from June to August, the water can be diverted into the lake through sluices. The greater the Δh (the water head between the Yangtze River and Playground Lake, the more the water quality will improve. Overall, the good-to-bad order of water quality improvements for Playground Lake is as follows: pumping 30 h > sluice diversion > no water diversion. This article is relevant for the environmental management of the artificial Playground Lake, and similar lakes elsewhere.

  2. Primary production in a shallow water lake with special reference to a reed swamp

    International Nuclear Information System (INIS)

    Andersen, F.Oe.

    1976-01-01

    Phytoplankton gross primary production ( 14 C method) in the shallow, eutrophic Danish Lake Arresoe in 1973 was 980 g C m -2 . Calculated net primary production was near zero. Macrophyte net primary production was measured by harvesting the maximum biomass, and above ground values were between 420 and 1325 g ash free dry wt m -2 , while below ground values were between 2480 and 8570 g ash free dry wt m -2 . The reed swamps were mapped on aerial photographs, and the composition of the macrophyte vegetation was determined. A comparison of macrophyte vegetation in 1944 and 1972 showed a reduction in species diversity, especially of submerged species. The seasonal variations in physical and chemical data indicated strong eutrophication in Arresoe. (author)

  3. Bioaccumulation and trophic transfer of mercury in a food web from a large, shallow, hypereutrophic lake (Lake Taihu) in China.

    Science.gov (United States)

    Wang, Shaofeng; Li, Biao; Zhang, Mingmei; Xing, Denghua; Jia, Yonfeng; Wei, Chaoyang

    2011-08-01

    Due to the fast development of industry and the overuse of agrichemicals in past decades, Lake Taihu, an important source of aquatic products for Eastern China, has simultaneously suffered mercury (Hg) contamination and eutrophication. The objectives of this study are to understand Hg transfer in the food web in this eutrophic, shallow lake and to evaluate the exposure risk of Hg through fish consumption. Biota samples including macrophytes, sestons, benthic animals, and fish were collected from Lake Taihu in the fall of 2009. The total mercury (THg), methyl mercury (MeHg), δ(13)C and δ(15)N in the samples were measured. The signature for δ(15)N increased with the trophic levels. Along with a diet composed of fish, the significant relationship between the δ(13)C and δ(15)N indicated that a pelagic foraging habitat is the dominant pathway for energy transfer in Lake Taihu. The concentrations of THg and MeHg in the organisms varied dramatically by ∼3 orders of magnitude from primary producers (macrophytes and sestons) to piscivorous fish. The highest concentrations of both THg (100 ng g(-1)) and MeHg (66 ng g(-1)), however, were lower than the guideline of 200 ng g(-1) of MeHg for vulnerable populations that is recommended by the World Health Organization (WHO). The daily intake of THg and MeHg of 92 and 56 ng day(-1) kg(-1) body weight, respectively, was generally lower than the tolerable intake of 230 ng day(-1) kg(-1) body weight for children recommended by the Joint FAO/WHO Expert Committee on Food Additives. Significant relationships between the δ(15)N and the logarithm of THg and MeHg showed an obvious biomagnification of Hg along the food web. The logarithmic bioaccumulation factor of MeHg in the fish (up to 5.7) from Lake Taihu, however, was relatively low compared to that of other aquatic ecosystems. Health risk of exposure to Hg by consumption of fish for local residents is relatively low in the Lake Taihu area. Dilution of Hg levels in

  4. Midges as palaeoindicators of lake productivity, eutrophication and hypolimnetic oxygen

    DEFF Research Database (Denmark)

    Brodersen, K. P.; Quinlan, R.

    2006-01-01

    , stratification patterns, water level change, sediment conditions, submerged vegetation and ecological thresholds are all important for interpretation of palaeolimnological trajectories. We use previously published and new data to document how these factors determine, change or preserve the "lake identity" over...

  5. Effects of Exposed Artificial Substrate on the Competition between Phytoplankton and Benthic Algae: Implications for Shallow Lake Restoration

    OpenAIRE

    Hu He; Xuguang Luo; Hui Jin; Jiao Gu; Erik Jeppesen; Zhengwen Liu; Kuanyi Li

    2017-01-01

    Phytoplankton and benthic algae coexist in shallow lakes and the outcome of the competition between these two photoautotrophs can markedly influence water clarity. It is well established that exposed artificial substrate in eutrophic waters can remove nutrients and fine particles from the water column via the attached periphyton canopy. However, the effects of the introduction of artificial substrate on the competition between planktonic and benthic primary producers remain to be elucidated. ...

  6. The Geochemical Record of Cultural Eutrophication and Remediation Efforts in Three Connecticut Lakes

    Science.gov (United States)

    Ku, T.; Bourne, H. L.; Tirtajana, S.; Nahar, M.; Kading, T.

    2009-12-01

    Cultural eutrophication is the process whereby human activity increases the amount of nutrients, primarily nitrogen and phosphorous, entering an aquatic ecosystem causing excessive biological growth. To reverse or decelerate cultural eutrophication, many regulatory agencies have implemented stringent laws intended to lower the flux of nutrients into impacted water bodies or have emplaced internal remediation systems designed to decrease primary productivity. To quantify the effects of cultural eutrophication and remediation efforts, we examined sedimentary histories of three eutrophic Connecticut lakes that record the transition from pre-anthropogenic conditions into eutrophication and through recent remediation. The three Connecticut lakes (Lake Waramaug, Beseck Lake, and Amos Lake) represent a range of remediation activities. Since 1983, Lake Waramaug has been the focus of significant remediation efforts including the installation of three hypolimnetic withdrawal / layer aeration systems, zoning regulations to limit runoff, and the stocking and seeding of fish and zooplankton. Beseck Lake has experienced episodic eutrophic conditions, in part due to failing septic systems, and in 2001, 433 residences were converted from septic systems to a city sewer system. Amos Lake serves as a cultural eutrophication end member as it has not has received any major remediation. Multiple freeze and gravity cores were collected from 2005-2008. Radiocarbon, Pb-210, Cs-137, Hg, and Pb measurements determined sediment ages. Organic C accumulation rates, C/N ratios, organic matter delta-15N, bulk sediment Fe and Al concentrations, and P speciation (labile, iron-bound, aluminum-bound, organic, and total) determined sediment and nutrient sources and accumulations. Dithionite-extractable iron, pyrite S, and pyrite delta-34S provided insight into changes in P-Fe-S cycling. The sediment cores represent the last few hundreds of years of lake history and, importantly, some Lake Waramaug

  7. Lake eutrophication and its implications for organic carbon sequestration in Europe.

    Science.gov (United States)

    Anderson, N J; Bennion, H; Lotter, A F

    2014-09-01

    The eutrophication of lowland lakes in Europe by excess nitrogen (N) and phosphorus (P) is severe because of the long history of land-cover change and agricultural intensification. The ecological and socio-economic effects of eutrophication are well understood but its effect on organic carbon (OC) sequestration by lakes and its change overtime has not been determined. Here, we compile data from ~90 culturally impacted European lakes [~60% are eutrophic, Total P (TP) >30 μg P l(-1) ] and determine the extent to which OC burial rates have increased over the past 100-150 years. The average focussing corrected, OC accumulation rate (C ARFC ) for the period 1950-1990 was ~60 g C m(-2) yr(-1) , and for lakes with >100 μg TP l(-1) the average was ~100 g C m(-2) yr(-1) . The ratio of post-1950 to 1900-1950 C AR is low (~1.5) indicating that C accumulation rates have been high throughout the 20th century. Compared to background estimates of OC burial (~5-10 g C m(-2) yr(-1) ), contemporary rates have increased by at least four to fivefold. The statistical relationship between C ARFC and TP derived from this study (r(2) = 0.5) can be used to estimate OC burial at sites lacking estimates of sediment C-burial. The implications of eutrophication, diagenesis, lake morphometry and sediment focussing as controls of OC burial rates are considered. A conservative interpretation of the results of the this study suggests that lowland European meso- to eutrophic lakes with >30 μg TP l(-1) had OC burial rates in excess of 50 g C m(-2) yr(-1) over the past century, indicating that previous estimates of regional lake OC burial have seriously underestimated their contribution to European carbon sequestration. Enhanced OC burial by lakes is one positive side-effect of the otherwise negative impact of the anthropogenic disruption of nutrient cycles. © 2014 John Wiley & Sons Ltd.

  8. Temperature and cyanobacterial bloom biomass influence phosphorous cycling in eutrophic lake sediments.

    Directory of Open Access Journals (Sweden)

    Mo Chen

    Full Text Available Cyanobacterial blooms frequently occur in freshwater lakes, subsequently, substantial amounts of decaying cyanobacterial bloom biomass (CBB settles onto the lake sediments where anaerobic mineralization reactions prevail. Coupled Fe/S cycling processes can influence the mobilization of phosphorus (P in sediments, with high releases often resulting in eutrophication. To better understand eutrophication in Lake Taihu (PRC, we investigated the effects of CBB and temperature on phosphorus cycling in lake sediments. Results indicated that added CBB not only enhanced sedimentary iron reduction, but also resulted in a change from net sulfur oxidation to sulfate reduction, which jointly resulted in a spike of soluble Fe(II and the formation of FeS/FeS2. Phosphate release was also enhanced with CBB amendment along with increases in reduced sulfur. Further release of phosphate was associated with increases in incubation temperature. In addition, CBB amendment resulted in a shift in P from the Fe-adsorbed P and the relatively unreactive Residual-P pools to the more reactive Al-adsorbed P, Ca-bound P and organic-P pools. Phosphorus cycling rates increased on addition of CBB and were higher at elevated temperatures, resulting in increased phosphorus release from sediments. These findings suggest that settling of CBB into sediments will likely increase the extent of eutrophication in aquatic environments and these processes will be magnified at higher temperatures.

  9. Management of eutrophication in Lake De Kuil (The Netherlands) using combined flocculant – Lanthanum modified bentonite treatment

    NARCIS (Netherlands)

    Waajen, Guido; van Oosterhout, Frank; Douglas, Grant; Lürling, Miquel

    2016-01-01

    Abstract Eutrophication of Lake De Kuil (The Netherlands, 6.7 ha, maximum depth 9 m) has frequently caused cyanobacterial blooms resulting in swimming bans or the issue of water quality warnings during summer. The eutrophication was mainly driven by sediment phosphorus (P)-release. The external

  10. Response of Submerged Macrophyte Communities to External and Internal Restoration Measures in North Temperate Shallow Lakes

    Science.gov (United States)

    Hilt, Sabine; Alirangues Nuñez, Marta M.; Bakker, Elisabeth S.; Blindow, Irmgard; Davidson, Thomas A.; Gillefalk, Mikael; Hansson, Lars-Anders; Janse, Jan H.; Janssen, Annette B. G.; Jeppesen, Erik; Kabus, Timm; Kelly, Andrea; Köhler, Jan; Lauridsen, Torben L.; Mooij, Wolf M.; Noordhuis, Ruurd; Phillips, Geoff; Rücker, Jacqueline; Schuster, Hans-Heinrich; Søndergaard, Martin; Teurlincx, Sven; van de Weyer, Klaus; van Donk, Ellen; Waterstraat, Arno; Willby, Nigel; Sayer, Carl D.

    2018-01-01

    Submerged macrophytes play a key role in north temperate shallow lakes by stabilizing clear-water conditions. Eutrophication has resulted in macrophyte loss and shifts to turbid conditions in many lakes. Considerable efforts have been devoted to shallow lake restoration in many countries, but long-term success depends on a stable recovery of submerged macrophytes. However, recovery patterns vary widely and remain to be fully understood. We hypothesize that reduced external nutrient loading leads to an intermediate recovery state with clear spring and turbid summer conditions similar to the pattern described for eutrophication. In contrast, lake internal restoration measures can result in transient clear-water conditions both in spring and summer and reversals to turbid conditions. Furthermore, we hypothesize that these contrasting restoration measures result in different macrophyte species composition, with added implications for seasonal dynamics due to differences in plant traits. To test these hypotheses, we analyzed data on water quality and submerged macrophytes from 49 north temperate shallow lakes that were in a turbid state and subjected to restoration measures. To study the dynamics of macrophytes during nutrient load reduction, we adapted the ecosystem model PCLake. Our survey and model simulations revealed the existence of an intermediate recovery state upon reduced external nutrient loading, characterized by spring clear-water phases and turbid summers, whereas internal lake restoration measures often resulted in clear-water conditions in spring and summer with returns to turbid conditions after some years. External and internal lake restoration measures resulted in different macrophyte communities. The intermediate recovery state following reduced nutrient loading is characterized by a few macrophyte species (mainly pondweeds) that can resist wave action allowing survival in shallow areas, germinate early in spring, have energy-rich vegetative

  11. Response of Submerged Macrophyte Communities to External and Internal Restoration Measures in North Temperate Shallow Lakes.

    Science.gov (United States)

    Hilt, Sabine; Alirangues Nuñez, Marta M; Bakker, Elisabeth S; Blindow, Irmgard; Davidson, Thomas A; Gillefalk, Mikael; Hansson, Lars-Anders; Janse, Jan H; Janssen, Annette B G; Jeppesen, Erik; Kabus, Timm; Kelly, Andrea; Köhler, Jan; Lauridsen, Torben L; Mooij, Wolf M; Noordhuis, Ruurd; Phillips, Geoff; Rücker, Jacqueline; Schuster, Hans-Heinrich; Søndergaard, Martin; Teurlincx, Sven; van de Weyer, Klaus; van Donk, Ellen; Waterstraat, Arno; Willby, Nigel; Sayer, Carl D

    2018-01-01

    Submerged macrophytes play a key role in north temperate shallow lakes by stabilizing clear-water conditions. Eutrophication has resulted in macrophyte loss and shifts to turbid conditions in many lakes. Considerable efforts have been devoted to shallow lake restoration in many countries, but long-term success depends on a stable recovery of submerged macrophytes. However, recovery patterns vary widely and remain to be fully understood. We hypothesize that reduced external nutrient loading leads to an intermediate recovery state with clear spring and turbid summer conditions similar to the pattern described for eutrophication. In contrast, lake internal restoration measures can result in transient clear-water conditions both in spring and summer and reversals to turbid conditions. Furthermore, we hypothesize that these contrasting restoration measures result in different macrophyte species composition, with added implications for seasonal dynamics due to differences in plant traits. To test these hypotheses, we analyzed data on water quality and submerged macrophytes from 49 north temperate shallow lakes that were in a turbid state and subjected to restoration measures. To study the dynamics of macrophytes during nutrient load reduction, we adapted the ecosystem model PCLake. Our survey and model simulations revealed the existence of an intermediate recovery state upon reduced external nutrient loading, characterized by spring clear-water phases and turbid summers, whereas internal lake restoration measures often resulted in clear-water conditions in spring and summer with returns to turbid conditions after some years. External and internal lake restoration measures resulted in different macrophyte communities. The intermediate recovery state following reduced nutrient loading is characterized by a few macrophyte species (mainly pondweeds) that can resist wave action allowing survival in shallow areas, germinate early in spring, have energy-rich vegetative

  12. Editorial - A critical perspective on geo-engineering for eutrophication management in lakes.

    Science.gov (United States)

    Lürling, Miquel; Mackay, Eleanor; Reitzel, Kasper; Spears, Bryan M

    2016-06-15

    Eutrophication is the primary worldwide water quality issue. Reducing excessive external nutrient loading is the most straightforward action in mitigating eutrophication, but lakes, ponds and reservoirs often show little, if any, signs of recovery in the years following external load reduction. This is due to internal cycling of phosphorus (P). Geo-engineering, which we can here define as activities intervening with biogeochemical cycles to control eutrophication in inland waters, represents a promising approach, under appropriate conditions, to reduce P release from bed sediments and cyanobacteria accumulation in surface waters, thereby speeding up recovery. In this overview, we draw on evidence from this special issue Geoengineering in Lakes, and on supporting literature to provide a critical perspective on the approach. We demonstrate that many of the strong P sorbents in the literature will not be applicable in the field because of costs and other constraints. Aluminium and lanthanum modified compounds are among the most effective compounds for targeting P. Flocculants and ballast compounds can be used to sink cyanobacteria, in the short term. We emphasize that the first step in managing eutrophication is a system analysis that will reveal the main water and P flows and the biological structure of the waterbody. These site specific traits can be significant confounding factors dictating successful eutrophication management. Geo-engineering techniques, considered collectively, as part of a tool kit, may ensure successful management of eutrophication through a range of target effects. In addition, novel developments in modified zeolites offer simultaneous P and nitrogen control. To facilitate research and reduce the delay from concept to market a multi-national centre of excellence is required. Copyright © 2016 Elsevier Ltd. All rights reserved.

  13. Mowing Submerged Macrophytes in Shallow Lakes with Alternative Stable States: Battling the Good Guys?

    Science.gov (United States)

    Kuiper, Jan J.; Verhofstad, Michiel J. J. M.; Louwers, Evelien L. M.; Bakker, Elisabeth S.; Brederveld, Robert J.; van Gerven, Luuk P. A.; Janssen, Annette B. G.; de Klein, Jeroen J. M.; Mooij, Wolf M.

    2017-04-01

    Submerged macrophytes play an important role in maintaining good water quality in shallow lakes. Yet extensive stands easily interfere with various services provided by these lakes, and harvesting is increasingly applied as a management measure. Because shallow lakes may possess alternative stable states over a wide range of environmental conditions, designing a successful mowing strategy is challenging, given the important role of macrophytes in stabilizing the clear water state. In this study, the integrated ecosystem model PCLake is used to explore the consequences of mowing, in terms of reducing nuisance and ecosystem stability, for a wide range of external nutrient loadings, mowing intensities and timings. Elodea is used as a model species. Additionally, we use PCLake to estimate how much phosphorus is removed with the harvested biomass, and evaluate the long-term effect of harvesting. Our model indicates that mowing can temporarily reduce nuisance caused by submerged plants in the first weeks after cutting, particularly when external nutrient loading is fairly low. The risk of instigating a regime shift can be tempered by mowing halfway the growing season when the resilience of the system is highest, as our model showed. Up to half of the phosphorus entering the system can potentially be removed along with the harvested biomass. As a result, prolonged mowing can prevent an oligo—to mesotrophic lake from becoming eutrophic to a certain extent, as our model shows that the critical nutrient loading, where the lake shifts to the turbid phytoplankton-dominated state, can be slightly increased.

  14. Editorial - A critical perspective on geo-engineering for eutrophication management in lakes

    DEFF Research Database (Denmark)

    Lürling, Miquel; Mackay, Eleanor; Reitzel, Kasper

    2016-01-01

    Eutrophication is the primary worldwide water quality issue. Reducing excessive external nutrient loading is the most straightforward action in mitigating eutrophication, but lakes, ponds and reservoirs often show little, if any, signs of recovery in the years following external load reduction...... accumulation in surface waters, thereby speeding up recovery. In this overview, we draw on evidence from this special issue Geoengineering in Lakes, and on supporting literature to provide a critical perspective on the approach. We demonstrate that many of the strong P sorbents in the literature...... will not be applicable in the field because of costs and other constraints. Aluminium and lanthanum modified compounds are among the most effective compounds for targeting P. Flocculants and ballast compounds can be used to sink cyanobacteria, in the short term. We emphasize that the first step in managing...

  15. Eutrophication of lakes and reservoirs: A framework for making management decisions

    Science.gov (United States)

    Rast, W.; Holland, M.

    1988-01-01

    The development of management strategies for the protection of environmental quality usually involves consideration both of technical and nontechnical issues. A logical, step-by-step framework for development of such strategies is provided. Its application to the control of cultured eutrophication of lakes and reservoirs illustrates its potential usefulness. From the perspective of the policymaker, the main consideration is that the eutrophication-related water quality of a lake or reservoir can be managed for given water uses. The approach presented here allows the rational assessment of relevant water-quality parameters and establishment of water-quality goals, consideration of social and other nontechnical issues, the possibilities of public involvement in the decision-making process, and a reasonable economic analysis within a management framework.

  16. Eutrophication in Poyang Lake (Eastern China over the Last 300 Years in Response to Changes in Climate and Lake Biomass.

    Directory of Open Access Journals (Sweden)

    Mengna Liao

    Full Text Available Poyang Lake is suffering from persistent eutrophication, which is degrading the local ecosystem. A better understanding of the mechanisms that drive eutrophication in lake systems is essential to fight the ongoing deterioration. In this study, hydraulic residence time (HRT was used to evaluate Poyang Lake's trophic state. A hydrology and ecosystem forced model was constructed to simulate long-term changes in algae and aquatic plant biomass and total phosphorous (TP. A comparison analysis revealed that between 1812 and 1828 (i.e., a consistent-change stage, climate and hydrology were the main driving forces, while algae and aquatic plant biomass contributed only 20.9% to the trophic changes in Poyang Lake. However, between 1844 and 1860 the biomass predominated contributing 63.6%. This could be attributed to nutrient absorption by algae and aquatic plants. A correlation analysis of the water TP and algae and aquatic plant biomass revealed a strong positive relationship. However, the algae and aquatic plant growth rate tended to decline after the biomass reached half of the maximum. This research reconstructs the long-term trophic evolution of Poyang Lake and provides a better understanding of the relationship between climatic and hydrological changes and lake ecosystems.

  17. Eutrophication in Poyang Lake (Eastern China) over the Last 300 Years in Response to Changes in Climate and Lake Biomass.

    Science.gov (United States)

    Liao, Mengna; Yu, Ge; Guo, Ya

    2017-01-01

    Poyang Lake is suffering from persistent eutrophication, which is degrading the local ecosystem. A better understanding of the mechanisms that drive eutrophication in lake systems is essential to fight the ongoing deterioration. In this study, hydraulic residence time (HRT) was used to evaluate Poyang Lake's trophic state. A hydrology and ecosystem forced model was constructed to simulate long-term changes in algae and aquatic plant biomass and total phosphorous (TP). A comparison analysis revealed that between 1812 and 1828 (i.e., a consistent-change stage), climate and hydrology were the main driving forces, while algae and aquatic plant biomass contributed only 20.9% to the trophic changes in Poyang Lake. However, between 1844 and 1860 the biomass predominated contributing 63.6%. This could be attributed to nutrient absorption by algae and aquatic plants. A correlation analysis of the water TP and algae and aquatic plant biomass revealed a strong positive relationship. However, the algae and aquatic plant growth rate tended to decline after the biomass reached half of the maximum. This research reconstructs the long-term trophic evolution of Poyang Lake and provides a better understanding of the relationship between climatic and hydrological changes and lake ecosystems.

  18. Phytoplankton Diversity Effects on Community Biomass and Stability along Nutrient Gradients in a Eutrophic Lake

    Directory of Open Access Journals (Sweden)

    Wang Tian

    2017-01-01

    Full Text Available The relationship between biodiversity and ecosystem functioning is a central issue in ecology, but how this relationship is affected by nutrient stress is still unknown. In this study, we analyzed the phytoplankton diversity effects on community biomass and stability along nutrient gradients in an artificial eutrophic lake. Four nutrient gradients, varying from slightly eutrophic to highly eutrophic states, were designed by adjusting the amount of polluted water that flowed into the lake. Mean phytoplankton biomass, species richness, and Shannon diversity index all showed significant differences among the four nutrient gradients. Phytoplankton community biomass was correlated with diversity (both species richness and Shannon diversity index, varying from positive to negative along the nutrient gradients. The influence of phytoplankton species richness on resource use efficiency (RUE also changed from positive to negative along the nutrient gradients. However, the influence of phytoplankton Shannon diversity on RUE was not significant. Both phytoplankton species richness and Shannon diversity had a negative influence on community turnover (measured as community dissimilarity, i.e., a positive diversity–stability relationship. Furthermore, phytoplankton spatial stability decreased along the nutrient gradients in the lake. With increasing nutrient concentrations, the variability (standard deviation of phytoplankton community biomass increased more rapidly than the average total biomass. Results in this study will be helpful in understanding the phytoplankton diversity effects on ecosystem functioning and how these effects are influenced by nutrient conditions in aquatic ecosystems.

  19. Epiphytic Diatoms along Environmental Gradients in Western European Shallow Lakes

    NARCIS (Netherlands)

    Blanco, Saul; Cejudo-Figueiras, Cristina; Alvarez-Blanco, Irene; van Donk, Ellen|info:eu-repo/dai/nl/069838593; Gross, Elisabeth M.; Hansson, Lars-Anders; Irvine, Kenneth; Jeppesen, Erik; Kairesalo, Timo; Moss, Brian; Noges, Tiina; Becares, Eloy

    Diatom-based assays have been successfully associated worldwide with the tropic status of lakes. Several studies have demonstrated a correlation between epiphytic diatoms and nutrient load in shallow lakes and wetlands. We examine the relative importance of environmental factors in explaining the

  20. Estimates of long-term water total phosphorus (TP) concentrations in three large shallow lakes in the Yangtze River basin, China.

    Science.gov (United States)

    Wu, Pan; Qin, Boqiang; Yu, Ge

    2016-03-01

    The shallow lakes in the eastern China developed on alluvial plains with high-nutrient sediments, and most overflow into the Yangtze River with short hydraulic residence times, whereas they become eutrophic over long time periods. Assuming strong responses to hydrogeological changes in the basin, we attempted to determine the dynamic eutrophication history of these lakes. Although evaluation models for internal total phosphorus (TP) loading are widely used for deep lakes in Europe and North America, the accuracy of these models for shallow lakes that have smaller water volumes controlled by the geometrical morphology and greater basin area of alluvial plains is unknown. To describe the magnitude of changes in velocity of trophic state for the studied shallow lakes, we first evaluated the P retention model in relation to the major forces driving lake morphology, basin climate, and external discharge and then used the model to estimate changes in TP in three large shallow lakes (Taihu, Chao, and Poyang) over 60 years (1950-2009 AD). The observed levels of TP were verified against the relative error of the three lakes (Yangtze River basin. This work will contribute to the development of an internal P loading model for further evaluating trophic states.

  1. The legacy of large regime shifts in shallow lakes.

    Science.gov (United States)

    Ramstack Hobbs, Joy M; Hobbs, William O; Edlund, Mark B; Zimmer, Kyle D; Theissen, Kevin M; Hoidal, Natalie; Domine, Leah M; Hanson, Mark A; Herwig, Brian R; Cotner, James B

    2016-12-01

    Ecological shifts in shallow lakes from clear-water macrophyte-dominated to turbid-water phytoplankton-dominated are generally thought of as rapid short-term transitions. Diatom remains in sediment records from shallow lakes in the Prairie Pothole Region of North America provide new evidence that the long-term ecological stability of these lakes is defined by the legacy of large regime shifts. We examine the modern and historical stability of 11 shallow lakes. Currently, four of the lakes are in a clear-water state, three are consistently turbid-water, and four have been observed to change state from year to year (transitional). Lake sediment records spanning the past 150-200 yr suggest that (1) the diatom assemblage is characteristic of either clear or turbid lakes, (2) prior to significant landscape alteration, all of the lakes existed in a regime of a stable clear-water state, (3) lakes that are currently classified as turbid or transitional have experienced one strong regime shift over the past 150-200 yr and have since remained in a regime where turbid-water predominates, and (4) top-down impacts to the lake food-web from fish introductions appear to be the dominant driver of strong regime shifts and not increased nutrient availability. Based on our findings we demonstrate a method that could be used by lake managers to identify lakes that have an ecological history close to the clear-turbid regime threshold; such lakes might more easily be returned to a clear-water state through biomanipulation. The unfortunate reality is that many of these lakes are now part of a managed landscape and will likely require continued intervention. © 2016 by the Ecological Society of America.

  2. Weather conditions influencing phosphorus concentration in the growing period in the large shallow Lake Peipsi (Estonia/Russia)

    OpenAIRE

    Tammeorg, Olga; Möls, Tonu; Kangur, Külli

    2014-01-01

    The impact of water temperature (T), water level (L), photosynthetically active radiation (PAR), and wind speed (V) on the total phosphorus concentration (TP) in shallow eutrophic lake Peipsi, the fourth largest lake in Europe, was studied. We used a long-term dataset (1985-2010) of TP concentrations and weather factors. A Thin Plate Spline (TPS) model was used to predict TP by year, by day of the year, and by geographical coordinates. Deviations between observed and predicted TP values (resi...

  3. A food web modeling analysis of a Midwestern, USA eutrophic lake dominated by non-native Common Carp and Zebra Mussels

    Science.gov (United States)

    Colvin, Michael E.; Pierce, Clay; Stewart, Timothy W.

    2015-01-01

    Food web modeling is recognized as fundamental to understanding the complexities of aquatic systems. Ecopath is the most common mass-balance model used to represent food webs and quantify trophic interactions among groups. We constructed annual Ecopath models for four consecutive years during the first half-decade of a zebra mussel invasion in shallow, eutrophic Clear Lake, Iowa, USA, to evaluate changes in relative biomass and total system consumption among food web groups, evaluate food web impacts of non-native common carp and zebra mussels on food web groups, and to interpret food web impacts in light of on-going lake restoration. Total living biomass increased each year of the study; the majority of the increase due to a doubling in planktonic blue green algae, but several other taxa also increased including a more than two-order of magnitude increase in zebra mussels. Common carp accounted for the largest percentage of total fish biomass throughout the study even with on-going harvest. Chironomids, common carp, and zebra mussels were the top-three ranking consumer groups. Non-native common carp and zebra mussels accounted for an average of 42% of the total system consumption. Despite the relatively high biomass densities of common carp and zebra mussel, food web impacts was minimal due to excessive benthic and primary production in this eutrophic system. Consumption occurring via benthic pathways dominated system consumption in Clear Lake throughout our study, supporting the argument that benthic food webs are significant in shallow, eutrophic lake ecosystems and must be considered if ecosystem-level understanding is to be obtained.

  4. Eutrophication and warming effects on long-term variation of zooplankton in Lake Biwa

    Directory of Open Access Journals (Sweden)

    C. H. Hsieh

    2011-05-01

    Full Text Available We compiled and analyzed long-term (1961–2005 zooplankton community data in response to environmental variations in Lake Biwa. Environmental data indicate that Lake Biwa had experienced eutrophication (according to the total phosphorus concentration in the late 1960s and recovered to a normal trophic status around 1985, and then has exhibited warming since 1990. Total zooplankton abundance showed a significant correlation with total phytoplankton biomass. Following a classic pattern, the cladoceran/calanoid and cyclopoid/calanoid abundance ratio was related positively to eutrophication. The zooplankton community exhibited a significant response to the boom and bust of phytoplankton biomass as a consequence of eutrophication-reoligotriphication and warming. Moreover, our analyses suggest that the Lake Biwa ecosystem exhibited a hierarchical response across trophic levels; that is, higher trophic levels may show a more delayed response or no response to eutrophication than lower ones.

    We tested the hypothesis that the phytoplankton community can better explain the variation of the zooplankton community than bulk environmental variables, considering that the phytoplankton community may directly affect the zooplankton succession through predator-prey interactions. Using a variance partition approach, however, we did not find strong evidence to support this hypothesis. We further aggregated zooplankton according to their feeding types (herbivorous, carnivorous, omnivorous, and parasitic and taxonomic groups, and analyzed the aggregated data. While the pattern remains similar, the results are less clear comparing the results based on finely resolved data. Our research suggests that zooplankton can be bio-indicators of environmental changes; however, the efficacy depends on data resolution.

  5. The Influence of Macrophytes on Sediment Resuspension and the Effect of Associated Nutrients in a Shallow and Large Lake (Lake Taihu, China)

    Science.gov (United States)

    Zhu, Mengyuan; Zhu, Guangwei; Nurminen, Leena; Wu, Tingfeng; Deng, Jianming; Zhang, Yunlin; Qin, Boqiang; Ventelä, Anne-Mari

    2015-01-01

    A yearlong campaign to examine sediment resuspension was conducted in large, shallow and eutrophic Lake Taihu, China, to investigate the influence of vegetation on sediment resuspension and its nutrient effects. The study was conducted at 6 sites located in both phytoplankton-dominated zone and macrophyte-dominated zone of the lake, lasting for a total of 13 months, with collections made at two-week intervals. Sediment resuspension in Taihu, with a two-week high average rate of 1771 g·m-2·d-1 and a yearly average rate of 377 g·m-2·d-1, is much stronger than in many other lakes worldwide, as Taihu is quite shallow and contains a long fetch. The occurrence of macrophytes, however, provided quite strong abatement of sediment resuspension, which may reduce the sediment resuspension rate up to 29-fold. The contribution of nitrogen and phosphorus to the water column from sediment resuspension was estimated as 0.34 mg·L-1 and 0.051 mg·L-1 in the phytoplankton-dominated zone. Sediment resuspension also largely reduced transparency and then stimulated phytoplankton growth. Therefore, sediment resuspension may be one of the most important factors delaying the recovery of eutrophic Lake Taihu, and the influence of sediment resuspension on water quality must also be taken into account by the lake managers when they determine the restoration target. PMID:26030094

  6. Floating rice-culture system for nutrient remediation and feed production in a eutrophic lake.

    Science.gov (United States)

    Srivastava, Ankita; Chun, Seong-Jun; Ko, So-Ra; Kim, Junhwan; Ahn, Chi-Yong; Oh, Hee-Mock

    2017-12-01

    The increased inputs of nutrients have been demonstrated to be a major contributing factor to the eutrophication of lakes and reservoirs which can lead to the production of harmful algal/cyanobacterial blooms and deleteriously affect the aesthetics of water-bodies. Floating plant-culture systems have been widely used for the ecological remediation of eutrophic water in a cost-effective manner. We investigated the applicability of Korean japonica rice variety 'Nampyeong' in a floating-culture system in a eutrophic lake for nutrient uptake and biomass production. Chemical and organic compound compositions were analyzed two times during the growth stages of the rice plant: 98 DAT (days after transplanting) and 165 DAT. Total nitrogen and phosphorus contributed around 1.36 and 0.15 (% dry weight), respectively, in rice plant components at 165 DAT. Crude protein, lipids, fiber and ash were 4.35, 1.91, 23.66 and 5.55 (% dry weight), respectively. In addition, microcystin levels in the rice plant components ranged from 0.0008 to 0.002 μg/g and did not exceed the recommended tolerable limits. These results suggested that the developed floating rice-culture system showed a good potential as a holistic management approach in terms of nutrient reduction, rice production for further use as feed and for bloom control. Copyright © 2017 Elsevier Ltd. All rights reserved.

  7. Sediment nitrogen cycling rates and microbial abundance along a submerged vegetation gradient in a eutrophic lake.

    Science.gov (United States)

    Yao, Lu; Chen, Chengrong; Liu, Guihua; Liu, Wenzhi

    2018-03-01

    Decline of submerged vegetation is one of the most serious ecological problems in eutrophic lakes worldwide. Although restoration of submerged vegetation is widely assumed to enhance ecological functions (e.g., nitrogen removal) and aquatic biodiversity, the evidence for this assumption is very limited. Here, we investigated the spatio-temporal patterns of sediment potential nitrification, unamended denitrification and N 2 O production rates along a vegetation gradient in the Lake Honghu, where submerged vegetation was largely restored by prohibiting net-pen aquaculture. We also used five functional genes as markers to quantify the abundance of sediment nitrifying and denitrifying microorganisms. Results showed that unvegetated sediments supported greater nitrification rates than rhizosphere sediments of perennial or seasonal vegetation. However, the absence of submerged vegetation had no significant effect on denitrification and N 2 O production rates. Additionally, the abundance of functional microorganisms in sediments was not significantly different among vegetation types. Season had a strong effect on both nitrogen cycling processes and microbial abundances. The highest nitrification rates were observed in September, while the highest denitrification rates occurred in December. The temporal variation of sediment nitrification, denitrification and N 2 O production rates could be due to changes in water quality and sediment properties rather than submerged vegetation and microbial abundances. Our findings highlight that vegetation restoration in eutrophic lakes improves water quality but does not enhance sediment nitrogen removal rates and microbial abundances. Therefore, for reducing the N level in eutrophic lakes, major efforts should be made to control nutrients export from terrestrial ecosystems. Copyright © 2017 Elsevier B.V. All rights reserved.

  8. Seasonal Variation of Eutrophication in Some Lakes of Danube Delta Biosphere Reserve.

    Science.gov (United States)

    Török, Liliana; Török, Zsolt; Carstea, Elfrida M; Savastru, Dan

    2017-01-01

      To understand the trophic state of lakes, this study aims to determine the dynamics of phytoplankton assemblages and the main factors that influence their seasonal variation. Sampling campaigns were carried out in three lakes from the Danube Delta Biosphere Reserve. Spectral analysis of specific phytoplankton pigments was applied as a diagnostic marker to establish the distribution and composition of phytoplankton taxonomic groups. Fluorescence spectroscopy was used to quantify changes in dissolved organic matter (DOM). The relative contribution of the main phytoplankton groups to the total phytoplankton biomass and the trend of development during succession of the seasons showed that cyanobacteria could raise potential ecological or human health problems. Moreover, fluorescence spectroscopy revealed that Cryptophyta and cyanobacteria were the main contributors to the protein-like components of DOM. It was concluded that fluorescence could be used to provide a qualitative evaluation of the eutrophication degree in Danube Delta lakes.

  9. A bibliometric review of nitrogen research in eutrophic lakes and reservoirs.

    Science.gov (United States)

    Yao, Xiaolong; Zhang, Yunlin; Zhang, Lu; Zhou, Yongqiang

    2018-04-01

    The global application of nitrogen is far greater than phosphorus, and it is widely involved in the eutrophication of lakes and reservoirs. We used a bibliometric method to quantitatively and qualitatively evaluate nitrogen research in eutrophic lakes and reservoirs to reveal research developments, current research hotspots, and emerging trends in this area. A total of 2695 articles in the past 25years from the online database of the Scientific Citation Index Expended (SCI-Expanded) were analyzed. Articles in this area increased exponentially from 1991 to 2015. Although the USA was the most productive country over the past 25years, China achieved the top position in terms of yearly publications after 2010. The most active keywords related to nitrogen in the past 25years included phosphorus, nutrients, sediment, chlorophyll-a, carbon, phytoplankton, cyanobacteria, water quality, modeling, and stable isotopes, based on analysis within 5-year intervals from 1991 to 2015 as well as the entire past 25years. In addition, researchers have drawn increasing attention to denitrification, climate change, and internal loading. Future trends in this area should focus on: (1) nutrient amounts, ratios, and major nitrogen sources leading to eutrophication; (2) nitrogen transformation and the bioavailability of different nitrogen forms; (3) nitrogen budget, mass balance model, control, and management; (4) ecosystem responses to nitrogen enrichment and reduction, as well as the relationships between these responses; and (5) interactions between nitrogen and other stressors (e.g., light intensity, carbon, phosphorus, toxic contaminants, climate change, and hydrological variations) in terms of eutrophication. Copyright © 2017. Published by Elsevier B.V.

  10. Spatiotemporal variability of carbon dioxide and methane in a eutrophic lake

    Science.gov (United States)

    Loken, Luke; Crawford, John; Schramm, Paul; Stadler, Philipp; Stanley, Emily

    2017-04-01

    Lakes are important regulators of global carbon cycling and conduits of greenhouse gases to the atmosphere; however, most efflux estimates for individual lakes are based on extrapolations from a single location. Within-lake variability in carbon dioxide (CO2) and methane (CH4) arises from differences in water sources, physical mixing, and local transformations; all of which can be influenced by anthropogenic disturbances and vary at multiple temporal and spatial scales. During the 2016 open water season (March - December), we mapped surface water concentrations of CO2 and CH4 weekly in a eutrophic lake (Lake Mendota, WI, USA), which has a predominately agricultural and urban watershed. In total we produced 26 maps of each gas based on 10,000 point measurements distributed across the lake surface. Both gases displayed relatively consistent spatial patterns over the stratified period but exhibited remarkable heterogeneity on each sample date. CO2 was generally undersaturated (global mean: 0.84X atmospheric saturation) throughout the lake's pelagic zone and often differed near river inlets and shorelines. The lake was routinely extremely supersaturated with CH4 (global mean: 105X atmospheric saturation) with greater concentrations in littoral areas that contained organic-rich sediments. During fall mixis, both CO2 and CH4 increased substantially, and concentrations were not uniform across the lake surface. CO2 and CH4 were higher on the upwind side of the lake due to upwelling of enriched hypolimnetic water. While the lake acted as a modest sink for atmospheric CO2 during the stratified period, the lake released substantial amounts of CO2 during turnover and continually emitted CH4, offsetting any reduction in atmospheric warming potential from summertime CO2 uptake. These data-rich maps illustrate how lake-wide surface concentrations and lake-scale efflux estimates based on single point measurements diverge from spatially weighted calculations. Both gases are not

  11. Eutrophication potential of lakes: an integrated analysis of trophic state, morphometry, land occupation, and land use

    Directory of Open Access Journals (Sweden)

    RF Silvino

    Full Text Available AbstractDespite being inside a protected area, Lake Sumidouro has been impacted by the anthropogenic occupation of the surrounding area since the 1970’s, compromising the ecological integrity of the lake and the sustainable use of natural resources. This study examined the current trophic classification of the lake and developed methods for improving it through an integrated analysis of morphometric and limnological parameters, land use and land occupation in the watershed, and eutrophication potential. Data for the limnological parameters, land use and land occupation, and morphometric characteristics of Lake Sumidouro were collected in the rainy and dry seasons of 2009 and 2010. Depending on the trophic classification system used, Lake Sumidouro is classified as oligotrophic to hypereutrophic. In our study, the highest concentration of nutrients occurred in the rainy season, indicating that high nutrient inputs played an important role during this period. Areas of anthropogenic occupation comprised approximately 62.9% of the total area of the watershed, with pasture and urban settlement as the main types of land use. The influent total phosphorus load was estimated to be 15,824.3 kg/year. To maintain mesotrophic conditions, this load must be reduced by 29.4%. By comparing the isolated use of trophic state indices, this study demonstrated that comparing the trophic state classification with morphometric analyses, land use and land occupation types in the watershed, and potential phosphorus load provided better information to guide management actions for restoration and conservation. Furthermore, this approach also allowed for evaluating the vulnerability of the environment to the eutrophication process.

  12. First report of the successful operation of a side stream supersaturation hypolimnetic oxygenation system in a eutrophic, shallow reservoir.

    Science.gov (United States)

    Gerling, Alexandra B; Browne, Richard G; Gantzer, Paul A; Mobley, Mark H; Little, John C; Carey, Cayelan C

    2014-12-15

    Controlling hypolimnetic hypoxia is a key goal of water quality management. Hypoxic conditions can trigger the release of reduced metals and nutrients from lake sediments, resulting in taste and odor problems as well as nuisance algal blooms. In deep lakes and reservoirs, hypolimnetic oxygenation has emerged as a viable solution for combating hypoxia. In shallow lakes, however, it is difficult to add oxygen into the hypolimnion efficiently, and a poorly designed hypolimnetic oxygenation system could potentially result in higher turbidity, weakened thermal stratification, and warming of the sediments. As a result, little is known about the viability of hypolimnetic oxygenation in shallow bodies of water. Here, we present the results from recent successful tests of side stream supersaturation (SSS), a type of hypolimnetic oxygenation system, in a shallow reservoir and compare it to previous side stream deployments. We investigated the sensitivity of Falling Creek Reservoir, a shallow (Zmax = 9.3 m) drinking water reservoir located in Vinton, Virginia, USA, to SSS operation. We found that the SSS system increased hypolimnetic dissolved oxygen concentrations at a rate of ∼1 mg/L/week without weakening stratification or warming the sediments. Moreover, the SSS system suppressed the release of reduced iron and manganese, and likely phosphorus, from the sediments. In summary, SSS systems hold great promise for controlling hypolimnetic oxygen conditions in shallow lakes and reservoirs. Copyright © 2014 Elsevier Ltd. All rights reserved.

  13. Geophysical problems of radiocesium removal from running shallow lakes

    International Nuclear Information System (INIS)

    Tarasiuk, N.; Spirkauskaite, N.; Gvozdaite, R. and others

    2002-01-01

    Natural processes of radiocesium removal from three selected running shallow (mean depth -0.7-4.2 m) lakes (Zuvintas, Asavas-Asavelis, Juodis) in Lithuania during 1999-2001 are studied. Lake sediments are of a sapropelic and peat type, rich in organics (47-68 %). 137 Cs activity concentrations in surface sediments varied in the range 100-360 Bq kg -1 . A sum of exchangeable and potentially mobile fractions of 137 Cs activity concentrations in lake sediments is assessed to vary in the range 10-34 %. The 137 CS enrichment coefficient defined as a ratio of annual sums of seasonal values of water-soluble 137 Cs activity concentrations in rivers outflowing from and in flowing to lakes was assessed to be equal for selected lakes from 1.4 to 2.5. A course of seasonal data demonstrates the efficiency of lake self cleaning from radiocesium to be minimum in winter owing to the priority of lake surface flows and the temperature stratification, suppressing the water column vertical mixing. It is suggested that elevated radiocesium activity concentrations in the outflowing rivers during a winter-spring transitional period are due to the presence of lake bottom flows. Lake isothermal stratification, inducing the water column vertical mixing during warm seasons, reinforces lake self cleaning processes. Considerations on the seasonal variations of the depth of the anoxic level in sediments, as well as on the vertical mixing of the surface sediments owing to the methane production, are discussed. (author)

  14. Water quality assessment in a shallow lake used for tourism

    Directory of Open Access Journals (Sweden)

    Dembowska Ewa A.

    2015-12-01

    Full Text Available The routine evaluation of water quality is limited to lakes with the largest area. In Poland, only lakes with an area exceeding 50 hectares are monitored by the State Environmental Monitoring System. For many local communities, however, small lakes are more important. This applies mainly to areas with a small number of lakes, where even the smallest lakes are used for various purposes. This paper presents the results of phytoplankton analysis in a small and shallow lake used for recreation. The study was conducted at three sites located in different parts of the lake. A total of 122 algae taxa were identified in the phytoplankton, mainly diatoms and green algae. The most constant taxa in the lake were: Stephanodiscus hantzschii, Desmodesmus communis, Pediastrum tetras and Crucigenia tetrapedia. The average phytoplankton biomass was 37 mg l−1. The maximum biomass, almost 140 mg dm−3, was recorded in late July at the site located near the beach. At that time, there was a massive cyanobacterial bloom composed of Microcystis wesenbergii and Aphanizomenon issatschenkoi. Based on these studies, the lake should be classified as hypertrophic with bad ecological status. This lake should not be used for recreational purposes in the current state.

  15. Assessing and addressing the re-eutrophication of Lake Erie: central basin hypoxia

    Science.gov (United States)

    Scavia, Donald; Allan, J. David; Arend, Kristin K.; Bartell, Steven; Beletsky, Dmitry; Bosch, Nate S.; Brandt, Stephen B.; Briland, Ruth D.; Daloğlu, Irem; DePinto, Joseph V.; Dolan, David M.; Evans, Mary Anne; Farmer, Troy M.; Goto, Daisuke; Han, Haejin; Höök, Tomas O.; Knight, Roger; Ludsin, Stuart A.; Mason, Doran; Michalak, Anna M.; Richards, R. Peter; Roberts, James J.; Rucinski, Daniel K.; Rutherford, Edward; Schwab, David J.; Sesterhenn, Timothy M.; Zhang, Hongyan; Zhou, Yuntao

    2014-01-01

    Relieving phosphorus loading is a key management tool for controlling Lake Erie eutrophication. During the 1960s and 1970s, increased phosphorus inputs degraded water quality and reduced central basin hypolimnetic oxygen levels which, in turn, eliminated thermal habitat vital to cold-water organisms and contributed to the extirpation of important benthic macroinvertebrate prey species for fishes. In response to load reductions initiated in 1972, Lake Erie responded quickly with reduced water-column phosphorus concentrations, phytoplankton biomass, and bottom-water hypoxia (dissolved oxygen 2) requires cutting total phosphorus loads by 46% from the 2003–2011 average or reducing dissolved reactive phosphorus loads by 78% from the 2005–2011 average. Reductions to these levels are also protective of fish habitat. We provide potential approaches for achieving those new loading targets, and suggest that recent load reduction recommendations focused on western basin cyanobacteria blooms may not be sufficient to reduce central basin hypoxia to 2000 km2.

  16. Algal bloom sedimentation induces variable control of lake eutrophication by phosphorus inactivating agents

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Changhui [State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing 210008 (China); Bai, Leilei [State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing 210008 (China); Graduate University of Chinese Academy of Sciences (China); Jiang, He-Long, E-mail: hljiang@niglas.ac.cn [State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing 210008 (China); Xu, Huacheng [State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing 210008 (China)

    2016-07-01

    Lake eutrophication typically occurs with a syndrome of algae breeding and biomass accumulation (e.g., algal blooms). Therefore, the effect of algal bloom sedimentation on eutrophication control by phosphorus (P) inactivating agents was assessed herein. Three commercial products, including aluminum (Al) sulfate, iron (Fe) sulfate, and a lanthanum-modified clay (Phoslock®), as well as one easily available by-product, drinking water treatment residue (DWTR), were selected. The most important finding was that during algae sedimentation, P immobilization from the overlying water by Al, Phoslock®, and DWTR was dominated by a long-term slow phase (> 150 d), while Fe has limited effectiveness on the immobilization. Further analysis indicated that the algae sedimentation effect was mainly due to the slow release of P from algae, leading to relatively limited P available for the inactivating agents. Then, a more unfavorable effect on the P immobilization capability of inactivating agents was caused by the induced anaerobic conditions, the released organic matter from algae, and the increased sulfide in the overlying water and sediments during sedimentation. Overall, algae sedimentation induced variable control of eutrophication by P inactivating agents. Accordingly, recommendations for future works about algal lake restoration were also proposed. - Highlights: • A long-term P immobilization by Phoslock®, DWTR, and Al was observed. • Fe had limited effectiveness on P pollution control for overlying water. • Al and Fe enhanced sulfur reduction, while DWTR and Phoslock® had minor effect. • The sedimentation reduced Al and La release from agents, but enhanced Fe release. • The agents changed organic matter compositions and structures in water columns.

  17. Rising CO2 levels will intensify phytoplankton blooms in eutrophic and hypertrophic lakes.

    Directory of Open Access Journals (Sweden)

    Jolanda M H Verspagen

    Full Text Available Harmful algal blooms threaten the water quality of many eutrophic and hypertrophic lakes and cause severe ecological and economic damage worldwide. Dense blooms often deplete the dissolved CO2 concentration and raise pH. Yet, quantitative prediction of the feedbacks between phytoplankton growth, CO2 drawdown and the inorganic carbon chemistry of aquatic ecosystems has received surprisingly little attention. Here, we develop a mathematical model to predict dynamic changes in dissolved inorganic carbon (DIC, pH and alkalinity during phytoplankton bloom development. We tested the model in chemostat experiments with the freshwater cyanobacterium Microcystis aeruginosa at different CO2 levels. The experiments showed that dense blooms sequestered large amounts of atmospheric CO2, not only by their own biomass production but also by inducing a high pH and alkalinity that enhanced the capacity for DIC storage in the system. We used the model to explore how phytoplankton blooms of eutrophic waters will respond to rising CO2 levels. The model predicts that (1 dense phytoplankton blooms in low- and moderately alkaline waters can deplete the dissolved CO2 concentration to limiting levels and raise the pH over a relatively wide range of atmospheric CO2 conditions, (2 rising atmospheric CO2 levels will enhance phytoplankton blooms in low- and moderately alkaline waters with high nutrient loads, and (3 above some threshold, rising atmospheric CO2 will alleviate phytoplankton blooms from carbon limitation, resulting in less intense CO2 depletion and a lesser increase in pH. Sensitivity analysis indicated that the model predictions were qualitatively robust. Quantitatively, the predictions were sensitive to variation in lake depth, DIC input and CO2 gas transfer across the air-water interface, but relatively robust to variation in the carbon uptake mechanisms of phytoplankton. In total, these findings warn that rising CO2 levels may result in a marked

  18. Algal bloom sedimentation induces variable control of lake eutrophication by phosphorus inactivating agents

    International Nuclear Information System (INIS)

    Wang, Changhui; Bai, Leilei; Jiang, He-Long; Xu, Huacheng

    2016-01-01

    Lake eutrophication typically occurs with a syndrome of algae breeding and biomass accumulation (e.g., algal blooms). Therefore, the effect of algal bloom sedimentation on eutrophication control by phosphorus (P) inactivating agents was assessed herein. Three commercial products, including aluminum (Al) sulfate, iron (Fe) sulfate, and a lanthanum-modified clay (Phoslock®), as well as one easily available by-product, drinking water treatment residue (DWTR), were selected. The most important finding was that during algae sedimentation, P immobilization from the overlying water by Al, Phoslock®, and DWTR was dominated by a long-term slow phase (> 150 d), while Fe has limited effectiveness on the immobilization. Further analysis indicated that the algae sedimentation effect was mainly due to the slow release of P from algae, leading to relatively limited P available for the inactivating agents. Then, a more unfavorable effect on the P immobilization capability of inactivating agents was caused by the induced anaerobic conditions, the released organic matter from algae, and the increased sulfide in the overlying water and sediments during sedimentation. Overall, algae sedimentation induced variable control of eutrophication by P inactivating agents. Accordingly, recommendations for future works about algal lake restoration were also proposed. - Highlights: • A long-term P immobilization by Phoslock®, DWTR, and Al was observed. • Fe had limited effectiveness on P pollution control for overlying water. • Al and Fe enhanced sulfur reduction, while DWTR and Phoslock® had minor effect. • The sedimentation reduced Al and La release from agents, but enhanced Fe release. • The agents changed organic matter compositions and structures in water columns.

  19. Rising CO2 Levels Will Intensify Phytoplankton Blooms in Eutrophic and Hypertrophic Lakes

    Science.gov (United States)

    Verspagen, Jolanda M. H.; Van de Waal, Dedmer B.; Finke, Jan F.; Visser, Petra M.; Van Donk, Ellen; Huisman, Jef

    2014-01-01

    Harmful algal blooms threaten the water quality of many eutrophic and hypertrophic lakes and cause severe ecological and economic damage worldwide. Dense blooms often deplete the dissolved CO2 concentration and raise pH. Yet, quantitative prediction of the feedbacks between phytoplankton growth, CO2 drawdown and the inorganic carbon chemistry of aquatic ecosystems has received surprisingly little attention. Here, we develop a mathematical model to predict dynamic changes in dissolved inorganic carbon (DIC), pH and alkalinity during phytoplankton bloom development. We tested the model in chemostat experiments with the freshwater cyanobacterium Microcystis aeruginosa at different CO2 levels. The experiments showed that dense blooms sequestered large amounts of atmospheric CO2, not only by their own biomass production but also by inducing a high pH and alkalinity that enhanced the capacity for DIC storage in the system. We used the model to explore how phytoplankton blooms of eutrophic waters will respond to rising CO2 levels. The model predicts that (1) dense phytoplankton blooms in low- and moderately alkaline waters can deplete the dissolved CO2 concentration to limiting levels and raise the pH over a relatively wide range of atmospheric CO2 conditions, (2) rising atmospheric CO2 levels will enhance phytoplankton blooms in low- and moderately alkaline waters with high nutrient loads, and (3) above some threshold, rising atmospheric CO2 will alleviate phytoplankton blooms from carbon limitation, resulting in less intense CO2 depletion and a lesser increase in pH. Sensitivity analysis indicated that the model predictions were qualitatively robust. Quantitatively, the predictions were sensitive to variation in lake depth, DIC input and CO2 gas transfer across the air-water interface, but relatively robust to variation in the carbon uptake mechanisms of phytoplankton. In total, these findings warn that rising CO2 levels may result in a marked intensification of

  20. Bacterial communities in the sediments of Dianchi Lake, a partitioned eutrophic waterbody in China.

    Directory of Open Access Journals (Sweden)

    Yaohui Bai

    Full Text Available Bacteria play an important role in the decomposition and cycling of a variety of compounds in freshwater aquatic environments, particularly nutrient-rich eutrophic lakes. A unique Chinese eutrophic lake--Dianchi--was selected for study because it has two separate and distinct basins, Caohai with higher organic carbon levels and Waihai with lower organic carbon levels. Sediment bacterial communities were studied in the two basins using samples collected in each season from June 2010 to March 2011. Barcoded pyrosequencing based on the 16 S rRNA gene found that certain common phyla, Proteobacteria, Bacteroidetes, Firmicutes and Chloroflexi, were dominant in the sediments from both basins. However, from the class to genus level, the dominant bacterial groups found in the sediments were distinct between the two basins. Correlation analysis revealed that, among the environmental parameters examined, total organic carbon (TOC accounted for the greatest proportion of variability in bacterial community. Interestingly, study results suggest that increasing allochthonous organic carbon could enhance bacterial diversity and biomass in the sediment. In addition, analysis of function genes (amoA and nosZ demonstrated that ammonia-oxidizing bacteria (AOB were dominant in sediments, with 99% belonging to Nitrosomonas. Denitrifying bacteria were comparatively diverse and were associated with some cultivatable bacteria.

  1. Bifurcations of optimal vector fields in the shallow lake model

    NARCIS (Netherlands)

    Kiseleva, T.; Wagener, F.O.O.

    2010-01-01

    The solution structure of the set of optimal solutions of the shallow lake problem, a problem of optimal pollution management, is studied as we vary the values of the system parameters: the natural resilience, the relative importance of the resource for social welfare and the future discount rate.

  2. Bifurcations of optimal vector fields in the shallow lake model

    NARCIS (Netherlands)

    Kiseleva, T.; Wagener, F.

    2009-01-01

    The solution structure of the set of optimal solutions of the shallow lake problem, a problem of optimal pollution management, is studied as we vary the values of the system parameters: the natural resilience, the relative importance of the resource for social welfare and the future discount rate.

  3. Determination and occurrence of retinoids in a eutrophic lake (Taihu Lake, China): cyanobacteria blooms produce teratogenic retinal.

    Science.gov (United States)

    Wu, Xiaoqin; Jiang, Jieqiong; Hu, Jianying

    2013-01-15

    Besides retinoic acids (RAs), some retinoids such as retinal (RAL) and retinol (ROH), which are considered as RA precursors in vertebrates, are also reported to be teratogenic agents. In this study we investigated four RA precursors including RAL, ROH, retinyl palmitate, and β-carotene in the eutrophic Taihu Lake, China, by developing a sensitive analytical method. RAL and β-carotene were widely detected in natural cyanobacteria blooms and lake water. Intracellular concentrations of RAL and β-carotene in blooms were 9.4 to 6.9 × 10(3) and 3.4 to 1.8 × 10(5) ng L(-1), respectively, and their concentrations in lake water were up to 1.4 × 10 ng L(-1) (RAL) and 9.8 × 10(2) ng L(-1) (β-carotene). The good correlation between intracellular concentrations of RAL and RAs implied that RAL was involved in the production of RAs by cyanobacteria blooms. Further examination of 39 cyanobacteria and algae species revealed that most species could produce RAL and β-carotene. The greatest amount of RAL was found in Chlamydomonas sp. (FACHB-715; 1.9 × 10(3) ng g(-1) dry weight). As the main cyanobacteria in Taihu Lake, many Microcystis species could produce high amounts of RAL and were thought to greatly contribute to the production of RAL measured in the blooms. Productions of RAL and β-carotene by cyanobacteria were associated with species, origin location, and growth stage. The results in this study present the existence of a potential risk to aquatic animals living in a eutrophic environment from a high concentration of RAL in cyanobacteria blooms and also provide a clue for further investigating the mechanism underlying the biosynthetic pathway of RAs in cyanobacteria and algae.

  4. An integrated method for removal of harmful cyanobacterial blooms in eutrophic lakes

    International Nuclear Information System (INIS)

    Wang Zhicong; Li Dunhai; Qin Hongjie; Li Yinxia

    2012-01-01

    As the eutrophication of lakes becomes an increasingly widespread phenomenon, cyanobacterial blooms are occurring in many countries. Although some research has been reported, there is currently no good method for bloom removal. We propose here a new two-step integrated approach to resolve this problem. The first step is the inactivation of the cyanobacteria via the addition of H 2 O 2 . We found 60 mg/L was the lowest effective dose for a cyanobacterial concentration corresponding to 100 μg/L chlorophyll-a. The second step is the flocculation and sedimentation of the inactivated cyanobacteria. We found the addition of lake sediment clay (2 g/L) plus polymeric ferric sulfate (20 mg/L) effectively deposited them on the lake bottom. Since algaecides and flocculants had been used separately in previous reports, we innovatively combined these two types of reagents to remove blooms from the lake surface and to improve the dissolved oxygen content of lake sediments. - Graphical abstract: The mechanism for the removal of cyanobacterial blooms by using H 2 O 2 , polymeric ferric sulfate (PFS) and lake sediment clay. Display Omitted Highlights: ► We combined algaecide and flocculants together to control cyanobacterial blooms. ► H 2 O 2 was used to irreversibly inactivate the photosynthesis of cyanobacteria. ► Lake sediment clay and polymeric ferric sulfate were used to deposit cyanobacteria. ► Removal rate was very high and re-suspension rate was very low under disturbance. ► The inactivated cyanobacteria could not serve as a seed source for the next bloom. - Inactivation by H 2 O 2 and sedimentation using polymeric ferric sulfate and sediment clay demonstrated high integrated efficiency in removal of cyanobacterial blooms.

  5. Identifying Watershed Regions Sensitive to Soil Erosion and Contributing to Lake Eutrophication--A Case Study in the Taihu Lake Basin (China).

    Science.gov (United States)

    Lin, Chen; Ma, Ronghua; He, Bin

    2015-12-24

    Taihu Lake in China is suffering from severe eutrophication partly due to non-point pollution from the watershed. There is an increasing need to identify the regions within the watershed that most contribute to lake water degradation. The selection of appropriate temporal scales and lake indicators is important to identify sensitive watershed regions. This study selected three eutrophic lake areas, including Meiliang Bay (ML), Zhushan Bay (ZS), and the Western Coastal region (WC), as well as multiple buffer zones next to the lake boundary as the study sites. Soil erosion intensity was designated as a watershed indicator, and the lake algae area was designated as a lake quality indicator. The sensitive watershed region was identified based on the relationship between these two indicators among different lake divisions for a temporal sequence from 2000 to 2012. The results show that the relationship between soil erosion modulus and lake quality varied among different lake areas. Soil erosion from the two bay areas was more closely correlated with water quality than soil erosion from the WC region. This was most apparent at distances of 5 km to 10 km from the lake, where the r² was as high as 0.764. Results indicate that soil erosion could be used as an indicator for identifying key watershed protection areas. Different lake areas need to be considered separately due to differences in geographical features, land use, and the corresponding effects on lake water quality.

  6. Factors controlling bacteria and protists in selected Mazurian eutrophic lakes (North-Eastern Poland) during spring

    Science.gov (United States)

    2013-01-01

    Background The bottom-up (food resources) and top-down (grazing pressure) controls, with other environmental parameters (water temperature, pH) are the main factors regulating the abundance and structure of microbial communities in aquatic ecosystems. It is still not definitively decided which of the two control mechanisms is more important. The significance of bottom-up versus top-down controls may alter with lake productivity and season. In oligo- and/or mesotrophic environments, the bottom-up control is mostly important in regulating bacterial abundances, while in eutrophic systems, the top-down control may be more significant. Results The abundance of bacteria, heterotrophic (HNF) and autotrophic (ANF) nanoflagellates and ciliates, as well as bacterial production (BP) and metabolically active cells of bacteria (CTC, NuCC, EST) were studied in eutrophic lakes (Mazurian Lake District, Poland) during spring. The studied lakes were characterized by high nanoflagellate (mean 17.36 ± 8.57 × 103 cells ml-1) and ciliate abundances (mean 59.9 ± 22.4 ind. ml-1) that were higher in the euphotic zone than in the bottom waters, with relatively low bacterial densities (4.76 ± 2.08 × 106 cells ml-1) that were lower in the euphotic zone compared to the profundal zone. Oligotrichida (Rimostrombidium spp.), Prostomatida (Urotricha spp.) and Scuticociliatida (Histiobalantium bodamicum) dominated in the euphotic zone, whereas oligotrichs Tintinnidium sp. and prostomatids Urotricha spp. were most numerous in the bottom waters. Among the staining methods used to examine bacterial cellular metabolic activity, the lowest percentage of active cells was recorded with the CTC (1.5–15.4%) and EST (2.7–14.2%) assay in contrast to the NuCC (28.8–97.3%) method. Conclusions In the euphotic zone, the bottom-up factors (TP and DOC concentrations) played a more important role than top-down control (grazing by protists) in regulating bacterial numbers and activity

  7. Is water age a reliable indicator for evaluating water quality effectiveness of water diversion projects in eutrophic lakes?

    Science.gov (United States)

    Zhang, Xiaoling; Zou, Rui; Wang, Yilin; Liu, Yong; Zhao, Lei; Zhu, Xiang; Guo, Huaicheng

    2016-11-01

    Water diversion has been applied increasingly to promote the exchange of lake water and to control eutrophication of lakes. The accelerated water exchange and mass transport by water diversion can usually be represented by water age. But the responses of water quality after water diversion is still disputed. The reliability of using water age for evaluating the effectiveness of water diversion projects in eutrophic lakes should be thereby explored further. Lake Dianchi, a semi-closed plateau lake in China, has suffered severe eutrophication since the 1980s, and it is one of the three most eutrophic lakes in China. There was no significant improvement in water quality after an investment of approximately 7.7 billion USD and numerous project efforts from 1996 to 2015. After the approval of the Chinese State Council, water has been transferred to Lake Dianchi to alleviate eutrophication since December 2013. A three-dimensional hydrodynamic and water quality model and eight scenarios were developed in this study to quantity the influence of this water diversion project on water quality in Lake Dianchi. The model results showed that (a) Water quality (TP, TN, and Chla) could be improved by 13.5-32.2%, much lower than the approximate 50% reduction in water age; (b) Water exchange had a strong positive relationship with mean TP, and mean Chla had exactly the same response to water diversion as mean TN; (c) Water level was more beneficial for improving hydrodynamic and nutrient concentrations than variation in the diverted inflowing water volume; (d) The water diversion scenario of doubling the diverted inflow rate in the wet season with the water level of 1886.5 m and 1887 m in the remaining months was the best water diversion mode for mean hydrodynamics and TP, but the scenario of doubling the diverted inflow rate in the wet season with 1887 m throughout the year was optimum for mean TN and Chla; (e) Water age influenced the effectiveness of water diversion on the

  8. THE OXYGEN REGIME OF A SHALLOW LAKE

    Directory of Open Access Journals (Sweden)

    Galina Zdorovennova

    2016-01-01

    Full Text Available The year-round measurement data of water temperature and dissolved oxygen content in a small boreal Lake Vendyurskoe in 2007–2013 were used to explore the hydrophysical prerequisits of anoxia and accumulation and emission of greenhouse gases. Typically, anoxia appears in the bottom layers of lakes in mid-winter and during the summer  stagnation. The thickness of the benthic anaerobic zone (dissolved oxygen concentration <2 mg·l–1 reached one meter in the end of the winter and at the peak of the summer stratification, except for the extremely hot summer of 2010, when it reached five meters. Synoptic conditions had a crucial influence on the formation and destruction of the benthic anaerobic zones in summer. The most favorable oxygen dynamics was observed during the cold summers of 2008, 2009, and 2012, when the repeated full mixings of the water column occurred under conditions of the cyclonic weather. In the winter periods, the early dates of ice season resulted in the most pronounced deficiency of oxygen.

  9. Emergent and floating-leaved macrophytes as refuge for zooplankton in a eutrophic temperate lake without submerged vegetation

    DEFF Research Database (Denmark)

    Cazzanelli, Matteo; Perlt, Trine Warming; Christoffersen, Kirsten Seestern

    2008-01-01

    Several studies have shown that submerged macrophytes provide a refuge for zooplankton against fish predation, whereas the role of emergent and floating-leaved species, which are often dominant in eutrophic turbid lakes, is far less investigated. Zooplankton density in open water and amongst....... As a consequence, especially in turbid lakes, the ecological role of these functional types of vegetation, and not merely that of submerged macrophyte species, should be taken into consideration....

  10. The role of benthic macrofauna on nitrogen cycling in eutrophic lake sediment

    Energy Technology Data Exchange (ETDEWEB)

    Svensson, J M

    1998-12-01

    This thesis concerns the role of sediment-living macrobenthos in the cycling of nitrogen species and nitrogen transformation in eutrophic freshwater sediments. In my thesis I have, employing {sup 15}N-isotope techniques in laboratory experiments, shown the importance of infaunal chironomid larvae and oligochaetes on denitrification in eutrophic lake sediments. Investigated benthic organisms not only expand the sediment surface with their permanent or non-permanent burrow constructions, they also transport water through the burrows continuously. This behaviour of intermittent water-pumping activity, provides the burrows with oxygen, and in addition, mediates the supply of nitrate to denitrifying zones. The highly dynamic oxygen climate within and narrow oxic zones around burrows, due to their radial geometry, provides a very short diffusion path for nitrate into surrounding anoxic zones. In my studies rates of denitrification were enhanced c. 3 to 6-fold by the influence of chironomids (Chironomus plumosus) and c. 2-fold by the influence of oligochaetes at comparable biomass. The difference in degree of stimulation is explained by species-specific habitat exploitation which could also be observed between different tube-dwelling species of chironomids. Besides chironomid biomass, the degree of enhancement of denitrification by chironomids was dependent on nitrate concentration in the overlying water, and water temperature. Nitrification was also seen to be stimulated by the infaunal macrobenthos but to a lesser degree than denitrification. It is suggested that bioturbated eutrophic sediment, under predominantly oxic bottom water conditions may act more pronouncedly as a sink for inorganic nitrogen relative to non-bioturbated sediment, and that bioturbated sediment above all, may be an important factor contributing to lowered transport of nitrogen to the coast. In order to sustain high nitrogen removal capacity in wetlands, ponds and lakes, it is further suggested

  11. Are the Lake Victoria fisheries threatened by exploitation or eutrophication? Towards an ecosystem-based approach to management

    NARCIS (Netherlands)

    Kolding, J.; Zwieten, van P.A.M.; Mkumbo, O.; Silsbe, G.; Hecky, R.

    2008-01-01

    Lake Victoria’s ecosystem has shown fundamental changes over its past recorded history in terms of nutrient loadings, productivity, faunal composition and fisheries. As yet, however, no attempt has been made to link the driving processes of eutrophication and fisheries to understand the feedback

  12. Ecological regime shifts and changes of lake ecosystem service in a shallow Yangtze lake (Taibai Lake, China) over the past 150 years

    Science.gov (United States)

    Dong, X.; Xu, M.; Yang, X.

    2017-12-01

    Shallow lakes provide a range of ecosystem services such as water supply, biodiversity, aquaculture, tourism, shipping and flood regulation. Over recent decades, many lakes have become severely deteriorated due to a coupled natural and human disturbance. Given the limited monitoring records, however, we still have little knowledge on how, when and why those lake experienced ecological status shifts, and how the lake ecosystem service changed. Paleolimnological techniques were widely used in understanding the historical environmental and ecological changes. Here, we chose a typical eutrophic shallow lake, Taibai Lake, and acquired geochemistry proxies, grain size, diatom, cladocera and chironomid from a 210Pb and 137Cs dated sediment core. Document records and monitoring data are also included as important marks of social and environmental change. A T-test based algorithm of STARS reveal at least two ecological shifts, respectively in the 1960s and the 1990s. The sudden shift in the 1960s is supposed to be influenced by a dam and sluice construction in the 1950s and another shift in the 1990s should be a critical transition due to the alternation of ecosystem structure for higher fishery production. Correspondingly, lake ecosystem service (LES) also experienced significant changes. Prior to 1930s, different types of LES kept relatively stable with low values. With the dam construction in the 1960s, the changed hydrological condition led to gradual increases in both regulation and provision service. However, with much effort on fishery and reclamation, the regulation service of the lake decreased, exhibiting a tradeoff among LES. After 1990s, with intense aquaculture, most types of LSE suffered a further decrease. The long-term records exhibited that ecosystem services in primary productivity and biodiversity maintenance increased (synergies) whereas services in water-purification and climate regulating decreased significantly (tradeoffs) since 1950s, when local

  13. Assessing lake eutrophication using chironomids: understanding the nature of community response in different lake types

    DEFF Research Database (Denmark)

    Langdon, P. G.; Ruiz, Z.; Brodersen, K. P.

    2006-01-01

    in the original calibration or extended datasets. However, since the transfer functions are based on weighted averages of the trophic optima for the taxa present and not on community similarities, reasonable downcore inferences were produced. Ordination analyses also showed that the lakes retain their 'identity......1. Total phosphorus (TP) and chlorophyll a (Chl a) chironomid inference models ( Brodersen & Lindegaard, 1999 ; Brooks, Bennion & Birks, 2001 ) were used in an attempt to reconstruct changes in nutrients from three very different lake types. Both training sets were expanded, particularly at the low....... A response to nutrients (TP or total nitrogen (TN) ) at this site is also indirect, and the TP reconstruction therefore cannot be reliably interpreted. The third lake, March Ghyll Reservoir has little change in historic chironomid communities, suggesting that this well mixed, relatively unproductive lake has...

  14. Cyanobacterial carbon concentrating mechanisms facilitate sustained CO2 depletion in eutrophic lakes

    Directory of Open Access Journals (Sweden)

    A. M. Morales-Williams

    2017-06-01

    Full Text Available Phytoplankton blooms are increasing in frequency, intensity, and duration in aquatic ecosystems worldwide. In many eutrophic lakes, these high levels of primary productivity correspond to periods of CO2 depletion in surface waters. Cyanobacteria and other groups of phytoplankton have the ability to actively transport bicarbonate (HCO3− across their cell membrane when CO2 concentrations are limiting, possibly giving them a competitive advantage over algae not using carbon concentrating mechanisms (CCMs. To investigate whether CCMs can maintain phytoplankton bloom biomass under CO2 depletion, we measured the δ13C signatures of dissolved inorganic carbon (δ13CDIC and phytoplankton particulate organic carbon (δ13Cphyto in 16 mesotrophic to hypereutrophic lakes during the ice-free season of 2012. We used mass–balance relationships to determine the dominant inorganic carbon species used by phytoplankton under CO2 stress. We found a significant positive relationship between phytoplankton biomass and phytoplankton δ13C signatures as well as a significant nonlinear negative relationship between water column ρCO2 and isotopic composition of phytoplankton, indicating a shift from diffusive uptake to active uptake by phytoplankton of CO2 or HCO3− during blooms. Calculated photosynthetic fractionation factors indicated that this shift occurs specifically when surface water CO2 drops below atmospheric equilibrium. Our results indicate that active HCO3− uptake via CCMs may be an important mechanism in maintaining phytoplankton blooms when CO2 is depleted. Further increases in anthropogenic pressure, eutrophication, and cyanobacteria blooms are therefore expected to contribute to increased bicarbonate uptake to sustain primary production.

  15. Cyanobacterial carbon concentrating mechanisms facilitate sustained CO2 depletion in eutrophic lakes

    Science.gov (United States)

    Morales-Williams, Ana M.; Wanamaker, Alan D., Jr.; Downing, John A.

    2017-06-01

    Phytoplankton blooms are increasing in frequency, intensity, and duration in aquatic ecosystems worldwide. In many eutrophic lakes, these high levels of primary productivity correspond to periods of CO2 depletion in surface waters. Cyanobacteria and other groups of phytoplankton have the ability to actively transport bicarbonate (HCO3-) across their cell membrane when CO2 concentrations are limiting, possibly giving them a competitive advantage over algae not using carbon concentrating mechanisms (CCMs). To investigate whether CCMs can maintain phytoplankton bloom biomass under CO2 depletion, we measured the δ13C signatures of dissolved inorganic carbon (δ13CDIC) and phytoplankton particulate organic carbon (δ13Cphyto) in 16 mesotrophic to hypereutrophic lakes during the ice-free season of 2012. We used mass-balance relationships to determine the dominant inorganic carbon species used by phytoplankton under CO2 stress. We found a significant positive relationship between phytoplankton biomass and phytoplankton δ13C signatures as well as a significant nonlinear negative relationship between water column ρCO2 and isotopic composition of phytoplankton, indicating a shift from diffusive uptake to active uptake by phytoplankton of CO2 or HCO3- during blooms. Calculated photosynthetic fractionation factors indicated that this shift occurs specifically when surface water CO2 drops below atmospheric equilibrium. Our results indicate that active HCO3- uptake via CCMs may be an important mechanism in maintaining phytoplankton blooms when CO2 is depleted. Further increases in anthropogenic pressure, eutrophication, and cyanobacteria blooms are therefore expected to contribute to increased bicarbonate uptake to sustain primary production.

  16. Possible Sediment Mixing and the Disparity between Field Measurements and Paleolimnological Inferences in Shallow Iowa Lakes in the Midwestern United States

    Directory of Open Access Journals (Sweden)

    Roger W. Bachmann

    2018-01-01

    Full Text Available Field measurements of water quality in Iowa lakes contradict paleolimnological studies that used 210Pb dating techniques in 33 lakes to infer accelerating eutrophication and sediment accumulation in recent decades. We tested this hypothesis by analyzing a series of water quality measurements taken in 24 of these lakes during the period 1972–2010. There was little change in the trophic state variables. Total phosphorus and algal chlorophylls did not increase, and Secchi depths did not decrease with no evidence that the lakes had become more eutrophic. Changes in daily sediment loads in the Raccoon River also did not match the paleolimnological inferred rates of soil erosion for the period 1905–2005, and an independent estimate of soil erosion rates showed a decline of 40% in the 1977 to 2012 period rather than an increase. We hypothesized that sediment mixing by benthivorous fish could be responsible for violating the basic assumption of 210Pb sediment dating that the sediments are not disturbed once they are laid down. We developed a mathematical model that demonstrated that sediment mixing could lead to false inferences about sediment dates and sediment burial rates. This study raises the possibility that sediment mixing in Iowa lakes and similar shallow, eutrophic lakes with benthivorous fish may cause significant sediment mixing that can compromise dating using 210Pb dating of sediment cores.

  17. Lake eutrophication and environmental change: A viability framework for resilience, vulnerability and adaptive capacity

    Science.gov (United States)

    Mathias, Jean-Denis; Rougé, Charles; Deffuant, Guillaume

    2013-04-01

    We present a simple stochastic model of lake eutrophication to demonstrate how the mathematical framework of viability theory fosters operational definitions of resilience, vulnerability and adaptive capacity, and then helps understand which response one should bring to environmental changes. The model represents the phosphorus dynamics, given that high concentrations trigger a regime change from oligotrophic to eutrophic, and causes ecological but also economic losses, for instance from tourism. Phosphorus comes from agricultural inputs upstream of the lake, and we will consider a stochastic input. We consider the system made of both the lake and its upstream region, and explore how to maintain the desirable ecological and economic properties of this system. In the viability framework, we translate these desirable properties into state constraints, then examine how, given the dynamics of the model and the available policy options, the properties can be kept. The set of states for which there exists a policy to keep the properties is called the viability kernel. We extend this framework to both major perturbations and long-term environmental changes. In our model, since the phosphorus inputs and outputs from the lake depend on rainfall, we will focus on extreme rainfall events and long-term changes in the rainfall regime. They can be described as changes in the state of the system, and may displace it outside the viability kernel. Its response can then be described using the concepts of resilience, vulnerability and adaptive capacity. Resilience is the capacity to recover by getting back to the viability kernel where the dynamics keep the system safe, and in this work we assume it to be the first objective of management. Computed for a given trajectory, vulnerability is a measure of the consequence of violating a property. We propose a family of functions from which cost functions and other vulnerability indicators can be derived for any trajectory. There can be

  18. Assessment of primary production in a eutrophic lake from carbon and nitrogen isotope ratios of a carnivorous fish

    International Nuclear Information System (INIS)

    Yoshioka, Takahito

    1991-01-01

    The carbon and nitrogen isotope ratios of Hypomesus transpacificus (a pond smelt) in a eutrophic lake, Lake Suwa, were measured from April to September in 1986 and 1987. The differences in the isotope ratios between these two years were observed. The stable isotopes were transferred from phytoplankton to zooplankton and pond smelt, associated with organic matters. Therefore, the difference in the isotope ratios in two years seemed to reflect the differences of the proceeding of primary production. It was suggested that the carbon and nitrogen isotope ratios of animal, whose trophic level is far from primary producer, can be the qualitative indicators for assessing the primary production in a lake ecosystem. (author)

  19. Effects of Exposed Artificial Substrate on the Competition between Phytoplankton and Benthic Algae: Implications for Shallow Lake Restoration

    Directory of Open Access Journals (Sweden)

    Hu He

    2017-01-01

    Full Text Available Phytoplankton and benthic algae coexist in shallow lakes and the outcome of the competition between these two photoautotrophs can markedly influence water clarity. It is well established that exposed artificial substrate in eutrophic waters can remove nutrients and fine particles from the water column via the attached periphyton canopy. However, the effects of the introduction of artificial substrate on the competition between planktonic and benthic primary producers remain to be elucidated. We conducted a short-term outdoor mesocosm experiment to test the hypothesis that the nutrient and light changes induced by exposed artificial substrate (polythene nets would benefit the benthic algae. Artificial substrate significantly reduced total nitrogen and phosphorus concentrations and water clarity improved, the latter due to the substrate-induced reduction of both organic and inorganic suspended solids. Consequently, as judged from changes in chlorophyll a (Chl-a concentrations in water and sediment, respectively, exposed artificial substrate significantly reduced the phytoplankton biomass, while benthic algae biomass increased. Our results thus indicate that exposed artificial substrate may be used as a tool to re-establish benthic primary production in eutrophic shallow lakes after an external nutrient loading reduction, paving the way for a benthic- or a macrophyte-dominated system. Longer term and larger scale experiments are, however, needed before any firm conclusions can be drawn on this.

  20. Rapid ecological shift following piscivorous fish introduction to increasingly eutrophic and warmer Lake Furnas (Azores Archipelago, Portugal): A paleoecological approach

    DEFF Research Database (Denmark)

    Buchaca, Teresa; Skov, Tue; Amsinck, Susanne Lildal

    2011-01-01

    Lake ecosystems are nowadays often subjected to multi-stressors, such as eutrophication, climate change, and fish manipulations, the effects of which can be difficult to disentangle, not least from the usual short-term limnological time-series that are available. However, multi-proxy paleoecologi......Lake ecosystems are nowadays often subjected to multi-stressors, such as eutrophication, climate change, and fish manipulations, the effects of which can be difficult to disentangle, not least from the usual short-term limnological time-series that are available. However, multi......, meteorological forcing, and fish species introduction for recent lake ecosystem development in Lake Furnas on the island of Sa˜o Miguel, the Azores. The lake was stocked with cyprinids in the late nineteenth century and recently also with piscivorous fish, and has been affected by increasing agricultural......, and cryptophytes. The composition of microbial and algal assemblages changed rapidly after Daphnia appearance, and the covariance between fish stocking, nutrient loading, and enhanced temperatures captured most of the variability in algae accumulation, and thus likely in lake primary production as well. Thus, lake...

  1. Eutrophication and Dreissena invasion as drivers of biodiversity: a century of change in the mollusc community of Oneida Lake.

    Directory of Open Access Journals (Sweden)

    Vadim A Karatayev

    Full Text Available Changes in nutrient loading and invasive species are among the strongest human-driven disturbances in freshwater ecosystems, but our knowledge on how they affect the biodiversity of lakes is still limited. We conducted a detailed historical analysis of the mollusc community of Oneida Lake based on our comprehensive lakewide study in 2012 and previous surveys dating back to 1915. In the early 20th century, the lake had a high water clarity, with abundant macrophytes and benthic algae, and hosted the most diverse molluscan community in New York State, including 32 gastropod and 9 unionid species. By the 1960s, lake turbidity increased during a period of anthropogenic eutrophication, resulting in a 38% decline in species richness and a 95% reduction in abundance of native gastropods grazing on benthic algae. Following the invasion of Dreissena spp. in 1991 and subsequent increases in water clarity, native gastropod species richness expanded by 37% and abundance increased 20-fold by 2012. In contrast, filter-feeding unionids were unaffected by increased turbidity during the period of eutrophication but were extirpated by dreissenids. Through contrasting effects on turbidity, eutrophication and Dreissena spp. have likely driven the observed changes in native grazing gastropods by affecting the abundance of light-limited benthic algae. Given the high species richness and ecological importance of benthic grazers, monitoring and managing turbidity is important in preserving molluscan diversity.

  2. Effects of N and P enrichment on competition between phytoplankton and benthic algae in shallow lakes: a mesocosm study.

    Science.gov (United States)

    Zhang, Xiufeng; Mei, Xueying; Gulati, Ramesh D; Liu, Zhengwen

    2015-03-01

    Competition for resources between coexisting phytoplankton and benthic algae, but with different habitats and roles in functioning of lake ecosystems, profoundly affects dynamics of shallow lakes in the process of eutrophication. An experiment was conducted to test the hypothesis that combined enrichment with nitrogen (N) and phosphorus (P) would be a greater benefit to phytoplankton than benthic algae. The growth of phytoplankton and benthic algae was measured as chlorophyll a (Chl a) in 12 shallow aquatic mesocosms supplemented with N, P, or both. We found that enrichment with N enhanced growth of benthic algae, but not phytoplankton. P enrichment had a negative effect on benthic algal growth, and no effect on the growth of phytoplankton. N+P enrichment had a negative effect on benthic algae, but enhanced the growth of phytoplankton, thus reducing the proportion of benthic algae contributing to the combined biomass of these two groups of primary producers. Thus, combined N+P enrichment is more favorable to phytoplankton in competition with benthic algae than enrichment with either N or P alone. Our study indicates that combined enrichment with N+P promotes the dominance of phytoplankton over benthic algae, with consequences for the trophic dynamics of shallow lake ecosystems.

  3. Remote sensing of euphotic depth in shallow tropical inland waters of Lake Naivasha using MERIS data

    CSIR Research Space (South Africa)

    Majozi, NP

    2014-05-01

    Full Text Available radiometric and limnological data collection was undertaken at Lake Naivasha. Atmospheric correction was done on the MERIS images using MERIS Neural Network algorithms, Case 2 Waters (C2R) and Eutrophic Lakes processors and the bright pixel atmospheric...

  4. Application of LANDSAT to the surveillance and control of lake eutrophication in the Great Lakes Basin

    Science.gov (United States)

    Rogers, R. H. (Principal Investigator)

    1975-01-01

    The author has identified the following significant results. Preliminary results in Saginaw Bay show that processed LANDSAT data provides a synoptic view of turbidity and circulation patterns that no degree of ground monitoring can provide. Processed imagery was produced to show nine discrete categories of turbidity, as indicated by nine Secchi depths between 0.3 and 3.3 meters. Analysis of lakes near Madison, Wisconsin show that inland lake water can be categorized by LANDSAT as clear, tannin, algal, and red clay. LANDSAT's capability to inventory watershed land use was throughly demonstrated in the Ohio-Kentucky-Indiana regional planning area. Computer tabulations providing area covered by each of 16 land use categories were rapidly and economically produced for each of the 225 watersheds and nine counties.

  5. Effects of dissolved organic matter leaching from macrophyte litter on black water events in shallow lakes.

    Science.gov (United States)

    He, Yuhong; Song, Na; Jiang, He-Long

    2018-04-01

    In recent years, the black water phenomenon has become an environmental event in eutrophic shallow lakes in China, leading to deterioration of lake ecosystems and potable water crises. Decomposition of macrophyte debris has been verified as a key inducement for black water events. In this study, the effects of the decomposition of dissolved organic matter (Kottelat et al., WASP 187:343-351, 2008) derived from macrophyte leachate on the occurrence of black water events are investigated to clarify the detailed mechanisms involved. Results show that dissolved organic matter (DOM) is composed of a trace of chromophoric DOM and mostly non-chromophoric dissolved organic matter (CDOM). DOM decomposition is accompanied by varied concentration of CDOM components, generation of organic particles, and increased microbial concentrations. These processes increase water chroma only during initial 48 h, so the intensified water color cannot be maintained by DOM decomposition alone. During DOM decomposition, microorganisms first consume non-CDOM, increasing the relative CDOM concentration and turning the water color to black (or brown). Simultaneously, tryptophan and aromatic proteins, which are major ingredients of CDOM, enhance UV light absorption, further aggravating the macroscopic phenomenon of black color. Our results show that DOM leached from decayed macrophytes promotes or even triggers the occurrence of black water events and should be taken more seriously in the future.

  6. Nearly a decade-long repeatable seasonal diversity patterns of bacterioplankton communities in the eutrophic Lake Donghu (Wuhan, China)

    Energy Technology Data Exchange (ETDEWEB)

    Yan, Qingyun [Environmental Microbiome Research Center and the School of Environmental Science and Engineering, Sun Yat-sen University, Guangzhou China; Key Laboratory of Aquatic Biodiversity and Conservation of Chinese Academy of Sciences, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan China; Stegen, James C. [Biological Sciences Division, Pacific Northwest National Laboratory, Richland WA USA; Yu, Yuhe [Key Laboratory of Aquatic Biodiversity and Conservation of Chinese Academy of Sciences, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan China; Deng, Ye [CAS Key Laboratory of Environmental Biotechnology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing China; Li, Xinghao [Key Laboratory of Aquatic Biodiversity and Conservation of Chinese Academy of Sciences, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan China; Wu, Shu [Key Laboratory of Aquatic Biodiversity and Conservation of Chinese Academy of Sciences, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan China; Dai, Lili [Key Laboratory of Aquatic Biodiversity and Conservation of Chinese Academy of Sciences, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan China; Zhang, Xiang [Key Laboratory of Aquatic Biodiversity and Conservation of Chinese Academy of Sciences, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan China; Li, Jinjin [Key Laboratory of Aquatic Biodiversity and Conservation of Chinese Academy of Sciences, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan China; Wang, Chun [Key Laboratory of Aquatic Biodiversity and Conservation of Chinese Academy of Sciences, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan China; Ni, Jiajia [Key Laboratory of Aquatic Biodiversity and Conservation of Chinese Academy of Sciences, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan China; Li, Xuemei [Key Laboratory of Aquatic Biodiversity and Conservation of Chinese Academy of Sciences, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan China; Hu, Hongjuan [Key Laboratory of Aquatic Biodiversity and Conservation of Chinese Academy of Sciences, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan China; Xiao, Fanshu [Environmental Microbiome Research Center and the School of Environmental Science and Engineering, Sun Yat-sen University, Guangzhou China; Feng, Weisong [Key Laboratory of Aquatic Biodiversity and Conservation of Chinese Academy of Sciences, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan China; Ning, Daliang [Department of Microbiology and Plant Biology, Institute for Environmental Genomics, University of Oklahoma, Norman OK USA; He, Zhili [Environmental Microbiome Research Center and the School of Environmental Science and Engineering, Sun Yat-sen University, Guangzhou China; Department of Microbiology and Plant Biology, Institute for Environmental Genomics, University of Oklahoma, Norman OK USA; Van Nostrand, Joy D. [Department of Microbiology and Plant Biology, Institute for Environmental Genomics, University of Oklahoma, Norman OK USA; Wu, Liyou [Department of Microbiology and Plant Biology, Institute for Environmental Genomics, University of Oklahoma, Norman OK USA; Zhou, Jizhong [Department of Microbiology and Plant Biology, Institute for Environmental Genomics, University of Oklahoma, Norman OK USA; State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing China; Earth Sciences Division, Lawrence Berkeley National Laboratory, Berkeley CA USA

    2017-05-21

    Uncovering which environmental factors have the greatest influence on community diversity patterns and how ecological processes govern community turnover are key questions related to understanding community assembly mechanisms. Although we have good understanding of plant and animal community assembly, the mechanisms regulating diversity patterns of aquatic bacterial communities in lake ecosystems remains poorly understood. Here we present nearly a decade-long time-series study of bacterioplankton communities from the eutrophic Lake Donghu (Wuhan, China) using 16S rRNA gene amplicon sequencing. We found strong repeatable seasonal patterns for the overall community, common (detected in more than 50% samples) and dominant bacterial taxa (relative abundance > 1%). Moreover, community composition tracked the seasonal temperature gradient, indicating that temperature is an important environmental factor controlling observed diversity patterns. Total phosphorus also contributed significantly to the seasonal shifts in bacterioplankton composition. However, any spatial pattern across the main lake areas was overwhelmed by temporal variability in this eutrophic lake system. Phylogenetic analysis further indicated that 75%-82% of community turnover was governed by homogeneous selection, suggesting that the bacterioplankton communities are mainly controlled by niche-based processes. However, dominant niches available within seasons might be occupied by similar combinations of bacterial taxa with modest dispersal rates throughout this lake system. This study gives us important insights into community assembly and seasonal turnover of lake bacterioplankton, it may be also useful to predict temporal patterns of other planktonic communities.

  7. Could an airburst above Canada at the Younger Dryas onset trigger lake eutrophication and acidification in central Europe?

    Czech Academy of Sciences Publication Activity Database

    Stuchlík, Evžen; Kletetschka, G.; Hořická, Zuzana; Hrubá, J.; Nábělek, L.; Svitavská-Svobodová, Helena; Bobek, Přemysl; Kadlec, Jaroslav; Takac, M.; Vondrák, D.

    2017-01-01

    Roč. 52, S1 (2017), A335-A335, č. článku 6247. ISSN 1086-9379. [Annual Meeting of the Meteoritical Society /80./. 23.07.2017-28.07.2017, Santa Fe] R&D Projects: GA ČR(CZ) GA17-05935S Institutional support: RVO:60077344 ; RVO:67985939 ; RVO:67985530 Keywords : airburst * lake * eutrophication * acidification * paleolimnology Subject RIV: DA - Hydrology ; Limnology; EH - Ecology, Behaviour (BU-J)

  8. Sediment biomarkers elucidate the Holocene ontogeny of a shallow lake.

    Directory of Open Access Journals (Sweden)

    T E Arnold

    Full Text Available We carried out geochemical analyses on a sediment core from Lake Harris, Florida (USA to identify sources of organic matter to the sediment throughout the Holocene, and relate changes in those sources to shifts in past climate and environmental conditions. We hypothesized that the sources of organic matter changed in response to regional hydrologic shifts following de-glaciation, and to human population expansion in the state during the 20th century. Hydroclimate shifts in Florida were related to: 1 a steady rise in relative sea level and the fresh water table that began in the early Holocene, 2 wetland formation and expansion ca. 5,000 cal yrs BP, and 3 the onset of the modern El Niño (ENSO cycle ~3,000 cal yrs BP. Stratigraphic changes in sediment variables from Lake Harris reflect each of these hydroclimate periods. Early in the Holocene, Lake Harris was a marsh-like system in a relatively dry, open-prairie environment. Organic sediments deposited at that time were derived largely from terrestrial sources, as inferred from high TOC/TN ratios, a dominance of longer-chain of n-alkanes (n-C29-31, relatively negative organic carbon isotope values (δ13CTOC, and low biogenic silica concentrations. In the middle Holocene, a positive shift in δ13CTOC coincided with the onset of wetter conditions in Florida. Submerged macrophyte biomarkers (n-C21-23 dominated, and during that period bulk organic carbon isotope values were most similar to δ13C values of mid-chain-length n-alkanes. In the late Holocene, δ13CTOC values declined, CaCO3 levels decreased to trace amounts, organic carbon concentrations increased and diatom biogenic silica concentrations increased from 10 to 120 mg g-1. Around 2,900 cal yrs BP, the effects of ENSO intensified and many Florida lakes deepened to their current limnetic state. Concentrations of algal and cyanobacterial biomarkers in the Lake Harris core increased by orders of magnitude after about AD 1940, in response to

  9. Biomanipulation in shallow lakes in The Netherlands: an evaluation of 18 case studies

    NARCIS (Netherlands)

    Meijer, M.L.; Boois, de I.; Scheffer, M.; Portielje, R.; Hosper, H.

    1999-01-01

    Eighteen shallow lakes in The Netherlands were subjected to biomanipulation, i.e. drastic reduction of the fish stock, for the purpose of lake restoration. The morphology and the nutrient level of the lakes differed, as did the measures applied. In some lakes biomanipulation was accompanied by

  10. Zooplankton grazing in a eutrophic lake: implications of diel vertical migration

    International Nuclear Information System (INIS)

    Lampert, W.; Taylor, B.E.

    1985-01-01

    During summer and fall, depth profiles of zooplankton community grazing were determined in situ during day and night in the Schoehsee, a small eutrophic lake. Labeled algae of two different sizes were mixed with the natural suspension of phytoplankton in a grazing chamber. A small blue-green alga (Synechococcus, 1 μm) was labeled with 32 P; a larger green alga (Scenedesmus, 4-15 μm) was labeled with 14 C. During summer, grazing in the upper 5 m was negligible during day but strong at night. Hence, algae grow relatively unimpeded by grazing during daytime but are harvested at night. Vertical and diel differences in grazing rates disappeared when the vertical migration ceased in fall. Selectivity of grazing was controlled by the zooplankton species composition. Eudiaptomus showed a strong preference for Scenedesmus. Daphnia showed a slight preference for Scenedesmus, but Ceriodaphnia preferred Synechococcus. Cyclopoid copepodites did not ingest the small blue-green. Because Daphnia and Eudiaptomus were dominant, grazing rates on larger cells were usually higher than grazing rates on the small cells. Negative electivity indices for scenedesmus occurred only when the biomass of large crustaceans was extremely low (near the surface, during day). Zooplankton biomass was the main factor controlling both vertical and seasonal variations in grazing. Highest grazing rates (65%/d) were measured during fall when zooplankton abundance was high. Because differential losses can produce substantial errors in the results, it was necessary to process the samples on the boat immediately after collection, without preservation

  11. Do lake littoral benthic invertebrates respond differently to eutrophication, hydromorphological alteration, land use and fish stocking?

    Directory of Open Access Journals (Sweden)

    Šiling Rebeka

    2016-01-01

    Full Text Available In order to provide adequate guidelines in freshwater management, managers need reliable bioindicators that can respond differently to varied stressors. Managers also have to consider hierarchical structure of environmental factors. Thus, our research aims to test the independence of taxa responses along environmental gradients and to examine in what order natural and anthropogenic factors constrain the structure of littoral benthic assemblages. The rank of explained variance of littoral benthic assemblage's variable group hierarchy was: land use > landscape characteristics > eutrophication > fish stocking > hydromorphological alteration. We determined nine gradients (two natural and seven stressor gradients, separated into five groups based on statistically significant differences in responsiveness of taxa. Apart from responsiveness to natural factors, littoral benthic invertebrates could be used as bioindicators for stressors reflecting urbanization, eutrophication, hydromorphological alteration and fish stocking. The taxonomical composition of littoral benthic invertebrates, especially when taxa with preference for certain relatively narrow environmental conditions along gradients are present, can be used to identify effects of key stressors. Our findings have profound implications for ecological assessment and management of lakes, as they indicate that benthic invertebrates can be used when the effects of multiple stressors need to be disentangled.

  12. Grazing rate of zebra mussel in a shallow eutrophicated bay of the Baltic Sea.

    Science.gov (United States)

    Oganjan, Katarina; Lauringson, Velda

    2014-12-01

    Benthic suspension feeding is an important process in coastal ecosystems. Among all the World's oceans, coastal ecosystems are the most modified by human impact and changing at accelerating pace. It is complicated to understand, how various environmental factors affect feeding rates of suspension feeders in their natural habitats. Thus, shapes of such relationships are poorly described for several intersections of environmental gradients. In this study, relationships between grazing rates of an invasive bivalve Dreissena polymorpha and ambient environmental factors were investigated in a turbid eutrophic bay of the central Baltic Sea using a novel modelling method of Boosted Regression Trees (BRT), a statistical tool able to handle non-normal distributions, complex relationships, and interactive effects. Feeding rates of mussels were derived from field populations by measuring the content of algal pigments in specimens collected from their natural habitat. The content of pigments was converted to feeding rate separately each time using field experiments measuring simultaneously the content of pigments and biodeposition of mussels. The results suggest that feeding rates of D. polymorpha are related to several environmental factors which gradients outreach the optimal range for the local mussel population. All the observed effects were non-linear with complex shapes. Variability along the resource gradient was the most important predictor of mussel feeding, followed by salinity and disturbance caused by wind. The most important interaction occurred between disturbance and resource gradient, while feeding function showed more plasticity along the latter. Mapping of environmental tipping points with the aid of machine learning methods may enable to concentrate the most relevant information about ecological functions worldwide. Copyright © 2014 Elsevier Ltd. All rights reserved.

  13. Impacts of extreme weather events on highly eutrophic marine ecosystem (Rogoznica Lake, Adriatic coast)

    Science.gov (United States)

    Ciglenečki, I.; Janeković, I.; Marguš, M.; Bura-Nakić, E.; Carić, M.; Ljubešić, Z.; Batistić, M.; Hrustić, E.; Dupčić, I.; Garić, R.

    2015-10-01

    Rogoznica Lake is highly eutrophic marine system located on the Eastern Adriatic coast (43°32‧N, 15°58‧E). Because of the relatively small size (10,276 m2) and depth (15 m) it experiences strong natural and indirect anthropogenic influences. Dynamics within the lake is characterized by the extreme and highly variable environmental conditions (seasonal variations in salinity and temperature, water stratification and mixing, redox and euxinic conditions, concentrations of nutrients) which significantly influence the biology inside the lake. Due to the high phytoplankton activity, the upper part of the water column is well oxygenated, while hypoxia/anoxia usually occurs in the bottom layers. Anoxic part of the water column is characterized with high concentrations of sulfide (up to 5 mM) and nutrients (NH4+ up to 315 μM; PO43- up to 53 μM; SiO44- up to 680 μM) indicating the pronounced remineralization of the allochthonous organic matter, produced in the surface waters. The mixolimnion varies significantly within a season feeling effects of the Adriatic atmospheric and ocean dynamics (temperature, wind, heat fluxes, rainfall) which all affect the vertical stability and possibly induce vertical mixing and/or turnover. Seasonal vertical mixing usually occurs during the autumn/winter upon the breakdown of the stratification, injecting oxygen-rich water from the surface into the deeper layers. Depending on the intensity and duration of the vertical dynamics (slower diffusion and/or faster turnover of the water layers) anoxic conditions could developed within the whole water column. Extreme weather events such as abrupt change in the air temperature accompanied with a strong wind and consequently heat flux are found to be a key triggering mechanism for the fast turnover, introducing a large amount of nutrients and sulfur species from deeper parts to the surface. Increased concentration of nutrients, especially ammonium, phosphate, and silicates persisting for

  14. Small-scale distribution and diel vertical migration of zooplankton in a shallow lake (Lake Naardermeer, the Netherlands)

    NARCIS (Netherlands)

    Cerbin, S.; Balayla, D.; Van de Bund, W.J.

    2003-01-01

    Small scale distribution and diurnal migration of zooplankton were investigated in lake Naardermeer, a shallow lake largely covered by uniform Chara beds. For sampling, pattern samplers with a number of inverted funnels facing towards the lake bottom and held in a frame were used. Samplers were

  15. TiO2 nanoparticles for the remediation of eutrophic shallow freshwater systems: Efficiency and impacts on aquatic biota under a microcosm experiment.

    Science.gov (United States)

    Bessa da Silva, Márcia; Abrantes, Nelson; Nogueira, Verónica; Gonçalves, Fernando; Pereira, Ruth

    2016-09-01

    The application of nanomaterials (NMs) in the remediation of eutrophic waters, particularly in the control of internal loading of nutrients, has been started, but limited investigations evaluated the effectiveness of these new treatment approaches and of their potential impacts on species from shallow freshwater lakes. The present work investigated, under a microcosm experiment, the application of a TiO2 nanomaterial both for reducing nutrient (mainly phosphorus and nitrogen forms) desorption and release from sediments (preventive treatment-PT) and for eliminating algal blooms (remediation treatment-RT). Furthermore, we also intended to assess the potential impacts of nano-TiO2 application on key freshwater species. The results showed the effectiveness of nano-TiO2 in controlling the release of phosphates from surface sediment and the subsequent reduction of total phosphorus in the water column. A reduction in total nitrogen was also observed. Such changes in nutrient dynamics contributed to a progressive inhibition of development of algae after the application of the NM in PT microcosms. Concerning the ability of nano-TiO2 to interact with algal cells, this interaction has likely occurred, mainly in RT, enhancing the formation of aggregates and their rapid settlement, thus reducing the algal bloom. Both treatments caused deleterious effects on freshwater species. In PT, Daphnia magna and Lemna minor showed a significant inhibition of several endpoints. Conversely, no inhibitory effect on the growth of Chironomus riparius was recorded. In opposite, C. riparius was the most affected species in RT microcosms. Such difference was probably caused by the formation of larger TiO2-algae aggregates in RT, under a high algal density, that rapidly settled in the sediment, becoming less available for pelagic species. In summary, despite the effectiveness of both treatments in controlling internal nutrient loading and in the mitigating algal bloom episodes, their negative

  16. Internal cycling, not external loading, decides the nutrient limitation in eutrophic lake: A dynamic model with temporal Bayesian hierarchical inference.

    Science.gov (United States)

    Wu, Zhen; Liu, Yong; Liang, Zhongyao; Wu, Sifeng; Guo, Huaicheng

    2017-06-01

    Lake eutrophication is associated with excessive anthropogenic nutrients (mainly nitrogen (N) and phosphorus (P)) and unobserved internal nutrient cycling. Despite the advances in understanding the role of external loadings, the contribution of internal nutrient cycling is still an open question. A dynamic mass-balance model was developed to simulate and measure the contributions of internal cycling and external loading. It was based on the temporal Bayesian Hierarchical Framework (BHM), where we explored the seasonal patterns in the dynamics of nutrient cycling processes and the limitation of N and P on phytoplankton growth in hyper-eutrophic Lake Dianchi, China. The dynamic patterns of the five state variables (Chla, TP, ammonia, nitrate and organic N) were simulated based on the model. Five parameters (algae growth rate, sediment exchange rate of N and P, nitrification rate and denitrification rate) were estimated based on BHM. The model provided a good fit to observations. Our model results highlighted the role of internal cycling of N and P in Lake Dianchi. The internal cycling processes contributed more than external loading to the N and P changes in the water column. Further insights into the nutrient limitation analysis indicated that the sediment exchange of P determined the P limitation. Allowing for the contribution of denitrification to N removal, N was the more limiting nutrient in most of the time, however, P was the more important nutrient for eutrophication management. For Lake Dianchi, it would not be possible to recover solely by reducing the external watershed nutrient load; the mechanisms of internal cycling should also be considered as an approach to inhibit the release of sediments and to enhance denitrification. Copyright © 2017 Elsevier Ltd. All rights reserved.

  17. Assessing Potential Algal Blooms in a Shallow Fluvial Lake by Combining Hydrodynamic Modelling and Remote-Sensed Images

    Directory of Open Access Journals (Sweden)

    Monica Pinardi

    2015-04-01

    Full Text Available Shallow fluvial lakes are dynamic ecosystems shaped by physical and biological factors and characterized by the coexistence of phytoplankton and macrophytes. Due to multiple interplaying factors, understanding the distribution of phytoplankton in fluvial lakes is a complex but fundamental issue, in the context of increasing eutrophication, climate change, and multiple water uses. We analyze the distribution of phytoplankton by combining remotely sensed maps of chlorophyll-a with a hydrodynamic model in a dammed fluvial lake (Mantua Superior Lake, Northern Italy. The numerical simulation of different conditions shows that the main hydrodynamic effects which influence algal distribution are related to the combined effect of advection due to wind forces and local currents, as well as to the presence of large gyres which induce recirculation and stagnation regions, favoring phytoplankton accumulation. Therefore, the general characters of the phytoplankton horizontal patchiness can be inferred from the results of the hydrodynamic model. Conversely, hyperspectral remote-sensing products can be used to validate this model, as they provide chlorophyll-a distribution maps. The integration of ecological, hydraulic, and remote-sensing techniques may therefore help the monitoring and protection of inland water quality, with important improvements in management actions by policy makers.

  18. Changes in the fish community and water quality during seven years of stocking piscivorous fish in a shallow lake

    DEFF Research Database (Denmark)

    Skov, Christian; Perrow, M.R.; Berg, Søren

    2002-01-01

    evaluated between predatory fish and potential prey and between zooplanktivorous or benthivorous fish and water quality parameters. In addition, potential consumption of piscivorous fishes was calculated. 3. The density of fish feeding on larger zooplankton or benthos (roach >15 cm, crucian carp >15 cm......1. Piscivores (annual stocking of 1000 individuals ha(-1) of 0+ pike and a single stocking of 30 kg ha(-1) of large 20-30 cm perch) were stocked in seven consecutive years in a shallow eutrophic lake in Denmark. The stocking programme aimed at changing food-web structure by reducing...... zooplanktivorous and benthivorous fish, with resultant effects on lower trophic levels and ultimately water quality. 2. The fish community and water quality parameters (Secchi depth, concentrations of total phosphorus, chlorophyll a and suspended solids) were monitored between 1996 and 2000 and relationships were...

  19. Effects of submerged macrophytes on the abundance and community composition of ammonia-oxidizing prokaryotes in a eutrophic lake.

    Science.gov (United States)

    Zhao, Da-yong; Luo, Juan; Zeng, Jin; Wang, Meng; Yan, Wen-ming; Huang, Rui; Wu, Qinglong L

    2014-01-01

    Abundances and community compositions of ammonia-oxidizing archaea (AOA) and ammonia-oxidizing bacteria (AOB) in unvegetated sediment and the rhizosphere sediments of three submerged macrophytes (Ceratophyllum demersum, Vallisneria spinulosa, and Potamogeton crispus) were investigated in a large, eutrophic freshwater lake, Lake Taihu. Abundances of archaeal ammonia monooxygenase alpha-subunit (amoA) gene (from 6.56 × 10(6) copies to 1.06 × 10(7) copies per gram of dry sediment) were higher than those of bacterial amoA (from 6.13 × 10(5) to 3.21 × 10(6) copies per gram of dry sediment) in all samples. Submerged macrophytes exhibited no significant effect on the abundance and diversity of archaeal amoA gene. C. demersum and V. spinulosa increased the abundance and diversity of bacterial amoA gene in their rhizosphere sediment. However, the diversity of bacterial amoA gene in the rhizosphere sediments of P. crispus was decreased. The data obtained in this study would be helpful to elucidate the roles of submerged macrophytes involved in the nitrogen cycling of eutrophic lake ecosystems.

  20. Fifty years of eutrophication and lake restoration reflected in sedimentary carbon and nitrogen isotopes of a small, hardwater lake (south Germany

    Directory of Open Access Journals (Sweden)

    Emanuel Braig

    2013-04-01

    Full Text Available This study analyses the response of the carbon and nitrogen isotopic composition of sedimentary organic matter to rapid human-induced eutrophication and meromixis as well as subsequent restoration efforts [in-lake phosphorus (P-Precipitation, P-remediation of the well inflow and multiannual destratification] in a 46-yr sediment core sequence (1963-2009 from Fischkaltersee, a small hard-water lake (S-Germany. In addition, the sediment record was compared with detailed data on water column chemistry during almost (1977-2009 the recorded history of eutrophication and trophic recovery of the named lake. While the onset of eutrophication resulted in an abrupt positive excursion (+2.4‰, the overall reaction of δ13CSOM to ongoing eutrophication and meromixis as well as to permanent hypolimnion aeration and trophic recovery is a continous negative trend (-3.7‰ with the most depleted signatures (-38.8‰ present in the youngest part of the core. This negative trend was not influenced by multiannual hypolimnion aeration, which although oxygenating bottom waters (>2 mg O2 L–1, did not reverse the increasing anoxis in the sediment, as is indicated by an declining Mn/Fe ratio. Hence, we conclude that in Fischkaltersee δ13CSOM was controlled by photoautotrophic input only during an early phase in the eutrophication process. The signal of intensifying microbially mediated carbon cycling processes in the sediment, i.e. methanogenesis and methanotrophy, was superimposed on the primary productivity signal by crossing a certain TP threshold (approx. TP=0.04 mg L–1. Sedimentary δ15N values exhibit an overall increase (+3.4‰ in reaction to the eutrophication process, while trophic recovery produces a continous decrease in the signal (-2.7‰. Linear correlation of δ15N to nitrate utilisation in the epilimnion, however, is rather weak (R2=0.33. Comparison between sediment δ15N values and water column data reveals that two negative shifts in the

  1. Nitrogen removal by denitrification in the sediments of a shallow lake

    NARCIS (Netherlands)

    Luijn, van F.

    1997-01-01

    Most surface waters in the Netherlands are highly eutrophicated due to high loadings with the nutrients nitrogen (N) and phosphorus (P). To improve the water quality of lakes often the phosphorus loading is reduced. Due to phosphorus release from the sediments the success of the recovery of

  2. Effect of substrate on periphyton communities and relationships among food web components in shallow hypertrophic lake

    Directory of Open Access Journals (Sweden)

    Tomasz Mieczan

    2012-07-01

    Full Text Available We studied the role of natural (common reed and artificial substrata (bamboo in structuring the abundance and taxonomic composition of periphyton assemblages. Investigations were conducted in a shallow, hypertrophic lake situated in the area of Polesie Lubelskie (Eastern Poland. Periphyton communities (algae, ciliates, small metazoa and chironomids on both types of substratum were sampled monthly, from May to November of 2007. Water samples for chemical analysis were collected together with biological samples. We selected the group of ten environmental variables which are the most important in determining the habitat conditions in highly eutrophic lakes: temperature, Secchi disc visibility, conductivity, dissolved oxygen, periphytic chlorophyll-a, N-NO3, N-NH4, TP, P-PO4 and total organic carbon (TOC. The abundances of periphytic algae, ciliates, metazoa and chironomids were significantly affected by season and substrate. On natural substrata, in all studied months, periphyton communities showed higher abundances. The results of PCA analysis confirmed the distinction between periphyton communities on natural and artificial substrata. The Monte Carlo permutation test showed that the periphyton communities on common reed were the most significantly affected by temperature, N-NO3, Secchi disc visibility and TOC. The communities on artificial substrata were significantly influenced by temperature, P-PO4 and TOC. On natural substrata biomass of periphytic algae was significantly negatively correlated with abundances of all groups of potential grazers (ciliates, metazoa, chironomids. On artificial substrata the relations between components of periphytic food web were stronger; correlation coefficients between algae, protists and chironomids were significant at P<0.01. The results of analysis indicate that periphytic algae can play an important role as food source for higher trophic levels. These interactions are less significant on natural (reed

  3. Climate-related differences in the dominance of submerged macrophytes in shallow lakes

    NARCIS (Netherlands)

    Kosten, S.; Kamarainen, A.; Jeppesen, E.; Nes, van E.H.; Peeters, E.T.H.M.; Lacerot, G.; Scheffer, M.

    2009-01-01

    It has been suggested that shallow lakes in warm climates have a higher probability of being turbid, rather than macrophyte dominated, compared with lakes in cooler climates, but little field evidence exists to evaluate this hypothesis. We analyzed data from 782 lake years in different climate zones

  4. Factors controlling hydrochemical and trophic state variables in 86 shallow lakes in Europe

    NARCIS (Netherlands)

    Nõges, P.; Nõges, T.; Tuvikene, L.; Smal, H.; Ligeza, S.; Kornijów, R.; Peczula, W.; Bécares, E.; Garcia-Criado, F.; Alvarez-Carrera, C.; Fernandez-Alaez, C.; Ferriol, C.; Miracle, R.M.; Vicente, E.; Romo, S.; Van Donk, E.; Van de Bund, W.J.; Jensen, J.P.; Gross, E.M.; Hansson, L-A.; Gyllström, M.; Nykänen, M.; De Eyto, E.; Irvine, K.; Stephen, D.; Collings, S.E.; Moss, B.

    2003-01-01

    In order to disentangle the causes of variations in water chemistry among European shallow lakes, we performed standardised sampling programs in 86 lakes along a latitudinal gradient from southern Spain to northern Sweden. Lakes with an area of 0.1 to 27 000 ha and mean depth of 0.4–5.6 m located in

  5. Removal of phosphate from eutrophic lakes through adsorption by in situ formation of magnesium hydroxide from diatomite.

    Science.gov (United States)

    Xie, Fazhi; Wu, Fengchang; Liu, Guijian; Mu, Yunsong; Feng, Chenglian; Wang, Huanhua; Giesy, John P

    2014-01-01

    Since in situ formation of Mg(OH)2 can efficiently sorb phosphate (PO4) from low concentrations in the environment, a novel dispersed magnesium oxide nanoflake-modified diatomite adsorbent (MOD) was developed for use in restoration of eutrophic lakes by removal of excess PO4. Various adsorption conditions, such as pH, temperature and contact time were investigated. Overall, sorption capacities increased with increasing temperature and contact time, and decreased with increasing pH. Adsorption of PO4 was well described by both the Langmuir isotherm and pseudo second-order models. Theoretical maximum sorption capacity of MOD for PO4 was 44.44-52.08 mg/g at experimental conditions. Characterization of PO4 adsorbed to MOD by use of X-ray powder diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and solid state (31)P nuclear magnetic resonance revealed that electrostatic attraction, surface complexation and chemical conversion in situ were the major forces in adsorption of PO4. Mg(OH)2 formed in situ had a net positive charge on the surface of the MOD that could adsorb PO4(3-) and HPO4(2-) anion to form surface complex and gradually convert to Mg3(PO4)2 and MgHPO4. Efficiency of removal of PO4 was 90% when 300 mg MOD/L was added to eutrophic lake water. Results presented here demonstrated the potential use of the MOD for restoration of eutrophic lakes by removal of excess PO4.

  6. Will the Oxygen-Phosphorus Paradigm Persist? - Expert Views of the Future of Management and Restoration of Eutrophic Lakes

    Science.gov (United States)

    Nygrén, Nina A.; Tapio, Petri; Horppila, Jukka

    2017-11-01

    In the age of climate change, the demand and lack of pure water challenges many communities. Substantial amount of effort is put in every year to manage and restore degraded lakes while the long-term effects of those efforts are only poorly known or monitored. Oxygenation, or aeration, is used extensively for the restoration of eutrophic lakes, although many studies question whether this process improves the status of the lakes in the long-term. The desired effect of oxygenation is based on paradigmatic theories that, in the light of recent literature, might not be adequate when long-term improvements are sought. This article canvasses expert views on the feasibility of the `oxygen-phosphorus paradigm' as well as the future of the management and restoration of eutrophic lakes, based on an international, two-rounded, expert panel survey (Delphi study), employing 200 freshwater experts from 33 nationalities, contacted at three conferences on the topic. The conclusion is that the oxygen-phosphorus paradigm seems to be rather persistent. The experts considered oxygenation to be a valid short-term lake restoration method, but not without harmful side-effects. In addition, experts' low level of trust in the adequacy of the scientific knowledge on the effects of restorations and in the use of the scientific knowledge as a basis of choice of restoration methods, could be signs of a paradigm shift towards an outlook emphasizing more effective catchment management over short-term restorations. The expert panel also anticipated that reducing external nutrient loads from both point and diffuse sources will succeed in the future.

  7. Antibiotic resistance genes in surface water of eutrophic urban lakes are related to heavy metals, antibiotics, lake morphology and anthropic impact.

    Science.gov (United States)

    Yang, Yuyi; Xu, Chen; Cao, Xinhua; Lin, Hui; Wang, Jun

    2017-08-01

    Urban lakes are impacted by heavy human activities and represent potential reservoirs for antibiotic resistance genes. In this study, six urban lakes in Wuhan, central China were selected to analyze the distribution of sulfonamide resistance (sul) genes, tetracycline resistance (tet) genes and quinolone resistance (qnr) genes and their relationship with heavy metals, antibiotics, lake morphology and anthropic impact. sul1 and sul2 were detected in all six lakes and dominated the types of antibiotic resistance genes, which accounted for 86.28-97.79% of the total antibiotic resistance gene abundance. For eight tested tet genes, antibiotic efflux pumps (tetA, tetB, tetC, and tetG) genes were all observed in six lakes and had higher relative abundance than ribosomal protection protein genes (tetM and tetQ). For 4 plasmid mediated quinolone resistance genes, only qnrD is found in all six lakes. The class I integron (intI1) is also found to be a very important media for antibiotic resistance gene propagation in urban lakes. The results of redundancy analysis and variation partitioning analysis showed that antibiotic and co-selection with heavy metals were the major factors driving the propagation of antibiotic resistance genes in six urban lakes. The heavily eutrophic Nanhu Lake and Shahu Lake which located in a high density building area with heavy human activities had the higher relative abundance of total antibiotic resistance genes. Our study could provide a useful reference for antibiotic resistance gene abundance in urban lakes with high anthropic impact.

  8. Hydrogen sulfide production and volatilization in a polymictic eutrophic saline lake, Salton Sea, California.

    Science.gov (United States)

    Reese, Brandi Kiel; Anderson, Michael A; Amrhein, Christopher

    2008-11-15

    The Salton Sea is a large shallow saline lake located in southern California that is noted for high sulfate concentrations, substantial algal productivity, and very warm water column temperatures. These conditions are well-suited for sulfide production, and sulfide has been implicated in summer fish kills, although no studies have been conducted to specifically understand hydrogen sulfide production and volatilization there. Despite polymictic mixing patterns and relatively short accumulation periods, the amount of sulfide produced is comparable to meromictic lakes. Sulfide levels in the Salton Sea reached concentrations of 1.2 mmol L(-1) of total free sulfide in the hypolimnion and 5.6 mmol L(-1) in the sediment pore water. Strong winds in late July mixed H2S into the surface water, where it depleted the entire water column of dissolved oxygen and reached a concentration of 0.1 mmol L(-1). Sulfide concentrations exceeded the toxicity threshold of tilapia (Oreochromis mossambicus) and combined with strong anoxia throughout the water column, resulted in a massive fish kill. The mixing of sulfide into the surface waters also increased atmospheric H2S concentrations, reaching 1.0 micromol m(-3). The flux of sulfide from the sediment into the water column was estimated to range from 2-3 mmol m(-2) day(-1) during the winter and up to 8 mmol m(-2) day(-1) during the summer. Application of the two-layer model for volatilization indicates that up to 19 mmol m(-2) day(-1) volatilized from the surface during the mixing event. We estimate that as much as 3400 Mg year(-1) or approximately 26% of sulfide that diffused into the water column from the deepest sediments may have been volatilized to the atmosphere.

  9. Occurrence, spatial distribution, sources, and risks of polychlorinated biphenyls and heavy metals in surface sediments from a large eutrophic Chinese lake (Lake Chaohu)

    DEFF Research Database (Denmark)

    He, Wei; Bai, Ze-Lin; Liu, Wen-Xiu

    2016-01-01

    Surface sediment from large and eutrophic Lake Chaohu was investigated to determine the occurrence, spatial distribution, sources, and risks of polychlorinated biphenyls (PCBs) and heavy metals in one of the five biggest freshwater lakes in China. Total concentration of PCBs (Σ34PCBs) in Lake...... and microbial degradation accounted for 34.2 % and 65.8 % of total PCBs using PMF, and PMF revealed that natural and anthropogenic sources of heavy metals accounted for 38.1 % and 61.8 %, respectively. CA indicated that some toxic heavy metals (e.g., Cd, In, Tl, and Hg) were associated with Ca–Na–Mg minerals......, and Hg were at levels of environmental concern. The sediment in the drinking water source area (DWSA) was threatened by heavy metals from other areas, and some fundamental solutions were proposed to protect the DWSA....

  10. Monitoring a newly re-born patient: water quality and cyanotoxin occurrence in a reconstructed shallow Mediterranean lake

    Directory of Open Access Journals (Sweden)

    Spyros Gkelis

    2017-05-01

    Full Text Available Lake Karla (Central Greece is a unique example - at European scale - of a shallow lake ecosystem that was dried in the 1960s and in 2009 started to be restored. The lake is listed in the network of the Greek protected areas as it is considered a vital aquatic ecosystem, in terms of biodiversity. It has, however, already been adversely affected by both agricultural and industrial land uses in the surrounding area, leading to eutrophication and shifting algal community towards bloom-forming toxic cyanobacterial species. After repeated heavy-blooms, cyanotoxin occurrence and mass fish kills, the local ecosystem management authority has implemented a water quality monitoring program (July 2013 - July 2015 to assess environmental pressures and the response of aquatic biota in the lake. Microscopic, immunological, and molecular techniques combined with physico-chemical parameters, complemented by liquid chromatography tandem mass spectrometry (LC-MS/MS, were used to monitor cyanobacteria blooms and the associated cyanotoxin production from three different sites in Lake Karla and from the adjacent Kalamaki Reservoir. Water quality was also assessed by the structure of benthic invertebrate community on the sediment. Cyanobacteria were the main phytoplankton component, representing more than 70% of the total phytoplankton abundance; dominant taxa belonged to Cylindrospermopsis raciborskii, Limnothrix redekei, Anabaenopsis elenkinii, and Microcystis spp. Euglenophytes (Euglena, diatoms (Nitzschia, and chlorophytes (Scenedesmus were also important phytoplankton constituents. LC-MS/MS confirmed the co-occurrence of microcystins, cylindrospermopsin, saxitoxin, neo-saxitoxin and anatoxin-a. The occurrence of cyanotoxins in relation to the persistent and dominant cyanobacteria and the impact of cyanobacterial harmful algal blooms on the newly constructed lake along with the land uses and the emergent mitigation measures are discussed.

  11. Spatial variations in food web structures with alternative stable states: evidence from stable isotope analysis in a large eutrophic lake

    Science.gov (United States)

    Li, Yunkai; Zhang, Yuying; Xu, Jun; Zhang, Shuo

    2018-03-01

    Food web structures are well known to vary widely among ecosystems. Moreover, many food web studies of lakes have generally attempted to characterize the overall food web structure and have largely ignored internal spatial and environmental variations. In this study, we hypothesize that there is a high degree of spatial heterogeneity within an ecosystem and such heterogeneity may lead to strong variations in environmental conditions and resource availability, in turn resulting in different trophic pathways. Stable carbon and nitrogen isotopes were employed for the whole food web to describe the structure of the food web in different sub-basins within Taihu Lake. This lake is a large eutrophic freshwater lake that has been intensively managed and highly influenced by human activities for more than 50 years. The results show significant isotopic differences between basins with different environmental characteristics. Such differences likely result from isotopic baseline differences combining with a shift in food web structure. Both are related to local spatial heterogeneity in nutrient loading in waters. Such variation should be explicitly considered in future food web studies and ecosystem-based management in this lake ecosystem.

  12. Spatial variations in food web structures with alternative stable states: evidence from stable isotope analysis in a large eutrophic lake

    Science.gov (United States)

    Li, Yunkai; Zhang, Yuying; Xu, Jun; Zhang, Shuo

    2017-05-01

    Food web structures are well known to vary widely among ecosystems. Moreover, many food web studies of lakes have generally attempted to characterize the overall food web structure and have largely ignored internal spatial and environmental variations. In this study, we hypothesize that there is a high degree of spatial heterogeneity within an ecosystem and such heterogeneity may lead to strong variations in environmental conditions and resource availability, in turn resulting in different trophic pathways. Stable carbon and nitrogen isotopes were employed for the whole food web to describe the structure of the food web in different sub-basins within Taihu Lake. This lake is a large eutrophic freshwater lake that has been intensively managed and highly influenced by human activities for more than 50 years. The results show significant isotopic differences between basins with different environmental characteristics. Such differences likely result from isotopic baseline differences combining with a shift in food web structure. Both are related to local spatial heterogeneity in nutrient loading in waters. Such variation should be explicitly considered in future food web studies and ecosystem-based management in this lake ecosystem.

  13. Weather conditions influencing phosphorus concentration in the growing period in the large shallow Lake Peipsi (Estonia/Russia

    Directory of Open Access Journals (Sweden)

    Olga Tammeorg

    2014-01-01

    Full Text Available The impact of water temperature (T, water level (L, photosynthetically active radiation (PAR, and wind speed (V on the total phosphorus concentration (TP in shallow eutrophic lake Peipsi, the fourth largest lake in Europe, was studied. We used a long-term dataset (1985-2010 of TP concentrations and weather factors. A Thin Plate Spline (TPS model was used to predict TP by year, by day of the year, and by geographical coordinates. Deviations between observed and predicted TP values (residuals, or TP anomalies were related to the weather variables to clarify how the weather anomalies in a year might correlate with the observed fluctuations in TP dynamics. Notable seasonal variations in TP, typical for many shallow lake systems, were found: TP was two to three times higher during late summer-early autumn than during winter. Patterns of TP variability were well predicted by using geographical coordinates, year and day of the year (R2=0.69; P<0.0001. However, TP anomalies were ascribed to the effects of T, L, PAR, and V, which were proved to play a significant additional role in TP dynamics. Moreover, L had consistently negative effects over the year, whereas the effects of T and PAR on TP change were seen to be dependent on the season. TP anomalies in lake Peipsi were most sensitive to wind anomalies. V was associated with frequent switches between increasing and decreasing TP values, though it appeared mainly as a negative driver of TP anomalies in the season prior to the 180th day, and as a positive driver in the subsequent season.

  14. Long-term Simulation Study about the Impact of submerse Macrophytes on thermal Stratification Dynamics and Transport Processes in an extreme shallow water lake - Lake Federsee

    Science.gov (United States)

    Wolf, Thomas; Pöschke, Franziska; Pflugbeil, Thomas

    2017-04-01

    Lake Federsee is formed primarily by ice age processes and was subjected to strong siltation processes in post-glacial times, while in the last two centuries anthropogenic impact due to amelioration projects became more important and determined it's morphometry. Lake Federsee has a maximum length of 2.4 km, a maximum width of 1.1 km and an area of approx. 1.4 km2. With respect to it's area Lake Federsee is the third largest lake in the federal state of Baden-Wuerttemberg situated in the south of Germany. It is characterized by its very flat bathymetry with a maximum depth of about 3.15 m and an average depth of about 1 m. In recent years Lake Federsee has undergone a strong reduction of the nutrient content, thus developing from hypertrophic states in the years 1980ies to eutrophic conditions in the years 2000ies. Since 2005 this development is accompanied by a change of the general habitus of the lake converting from a lake dominated by algae to a lake dominated by macrophytes. Changing successions of aquatic plants have been observed in the lake with strong seasonal variations in the composition and density of the vegetation cover, however forming often an almost complete coverage of the lake. In the present study the implementation of the hydrodynamic, three-dimensional model DELFT3D - FLOW for this extreme shallow water lake will be presented. The impact of some numerical parameters will be investigated in a sensitivity study, which is aiming to set up the hydrodynamic model in an optimal way. This 3-dim hydrodynamic model is used to simulate the 3-dim flow field and to investigate the thermal stratification as well as the mixing processes taking place in this lake. The model is run for the simulation time period 2000 - 2016 having a horizontal resolution of dx=dy=50 m and 10 or 20 equidistantly spaced fixed vertical layers giving a vertical resolution of 0.32 or 0.16 m respectively. The timestep is choosen to be dt = 10 s. Analysis of the simulated vertical

  15. Use of metabolic inhibitors to estimate protozooplankton grazing and bacterial production in a monomictic eutrophic lake with an anaerobic hypolimnion

    International Nuclear Information System (INIS)

    Sanders, R.W.; Porter, K.G.

    1986-01-01

    Inhibitors of eucaryotes (cycloheximide and amphotericin B) and procaryotes (penicillin and chloramphenical) were used to estimate bacterivory and bacterial production in a eutrophic lake. Bacterial production appeared to be slightly greater than protozoan grazing in the aerobic waters of Lake Oglethorpe. Use of penicillin and cycloheximide yielded inconsistent results in anaerobic water and in aerobic water when bacterial production was low. Production measured by inhibiting eucaryotes with cycloheximide did not always agree with [ 3 H]thymidine estimates or differential filtration methods. Laboratory experiments showed that several common freshwater protozoans continued to swim and ingest bacterium-size latex beads in the presence of the eucaryote inhibitor. Penicillin also affected grazing rates of some ciliates. The authors recommended that caution and a corroborating method be used when estimating ecologically important parameters with specific inhibitors

  16. Spatial statistics of hydrography and water chemistry in a eutrophic boreal lake based on sounding and water samples.

    Science.gov (United States)

    Leppäranta, Matti; Lewis, John E; Heini, Anniina; Arvola, Lauri

    2018-06-04

    Spatial variability, an essential characteristic of lake ecosystems, has often been neglected in field research and monitoring. In this study, we apply spatial statistical methods for the key physics and chemistry variables and chlorophyll a over eight sampling dates in two consecutive years in a large (area 103 km 2 ) eutrophic boreal lake in southern Finland. In the four summer sampling dates, the water body was vertically and horizontally heterogenic except with color and DOC, in the two winter ice-covered dates DO was vertically stratified, while in the two autumn dates, no significant spatial differences in any of the measured variables were found. Chlorophyll a concentration was one order of magnitude lower under the ice cover than in open water. The Moran statistic for spatial correlation was significant for chlorophyll a and NO 2 +NO 3 -N in all summer situations and for dissolved oxygen and pH in three cases. In summer, the mass centers of the chemicals were within 1.5 km from the geometric center of the lake, and the 2nd moment radius ranged in 3.7-4.1 km respective to 3.9 km for the homogeneous situation. The lateral length scales of the studied variables were 1.5-2.5 km, about 1 km longer in the surface layer. The detected spatial "noise" strongly suggests that besides vertical variation also the horizontal variation in eutrophic lakes, in particular, should be considered when the ecosystems are monitored.

  17. Effects of dissolved organic matter from a eutrophic lake on the freely dissolved concentrations of emerging organic contaminants.

    Science.gov (United States)

    Xiao, Yi-Hua; Huang, Qing-Hui; Vähätalo, Anssi V; Li, Fei-Peng; Chen, Ling

    2014-08-01

    The authors studied the effects of dissolved organic matter (DOM) on the bioavailability of bisphenol A (BPA) and chloramphenicol by measuring the freely dissolved concentrations of the contaminants in solutions containing DOM that had been isolated from a mesocosm in a eutrophic lake. The abundance and aromaticity of the chromophoric DOM increased over the 25-d mesocosm experiment. The BPA freely dissolved concentration was 72.3% lower and the chloramphenicol freely dissolved concentration was 56.2% lower using DOM collected on day 25 than using DOM collected on day 1 of the mesocosm experiment. The freely dissolved concentrations negatively correlated with the ultraviolent absorption coefficient at 254 nm and positively correlated with the spectral slope of chromophoric DOM, suggesting that the bioavailability of these emerging organic contaminants depends on the characteristics of the DOM present. The DOM-water partition coefficients (log KOC ) for the emerging organic contaminants positively correlated with the aromaticity of the DOM, measured as humic acid-like fluorescent components C1 (excitation/emission=250[313]/412 nm) and C2 (excitation/emission=268[379]/456 nm). The authors conclude that the bioavailability of emerging organic contaminants in eutrophic lakes can be affected by changes in the DOM. © 2014 SETAC.

  18. Sediment dynamics in a large shallow lake characterized by seasonal flood pulse in Southeast Asia.

    Science.gov (United States)

    Siev, Sokly; Yang, Heejun; Sok, Ty; Uk, Sovannara; Song, Layheang; Kodikara, Dilini; Oeurng, Chantha; Hul, Seingheng; Yoshimura, Chihiro

    2018-08-01

    Most of studies on sediment dynamics in stable shallow lakes focused on the resuspension process as it is the dominant process. However, understanding of sediment dynamics in a shallow lake influenced by flood pulse is unclear. We tested a hypothesis that floodplain vegetation plays as a significant role in lessening the intensity of resuspension process in a shallow lake characterized by the flood pulse system. Therefore, this study aimed to investigate sediment dynamics in this type of shallow lake. The target was Tonle Sap Lake (TSL), which is a large shallow lake influenced by a flood pulse system of Mekong River located in Southeast Asia. An extensive and seasonal sampling survey was conducted to measure total suspended solid (TSS) concentrations, sedimentation and resuspension rates in TSL and its 4 floodplain areas. The study revealed that sedimentation process was dominant (TSS ranged: 3-126mgL -1 ) in the high water period (September-December) while resuspension process was dominant (TSS ranged: 4-652mgL -1 ) only in the low water period (March-June). In addition, floodplain vegetation reduced the resuspension of sediment (up to 26.3%) in water. The implication of the study showed that resuspension is a seasonally dominant process in shallow lake influenced by the flood pulse system at least for the case of TSL. Copyright © 2018 Elsevier B.V. All rights reserved.

  19. Regime shifts in shallow lakes: the importance of seasonal fish migration

    DEFF Research Database (Denmark)

    Brönmark, Christer; Brodersen, Jakob; Chapman, Ben B.

    2010-01-01

    . Our earlier research shows that a large proportion of zooplanktivorous fish populations in shallow lakes undertake seasonal migrations where they leave the lake during winter and migrate back to the lake in spring. Based on our past research, we propose a number of scenarios of how feedback processes...... properties, including piscivore abundance and zooplankton productivity, affect the individual state of zooplanktivorous fish, such as growth rate or condition. Individual state, in turn, affects the relative proportion and timing of migrating zooplanktivorous fish. This change, in turn, may stabilize states...... between the individual and ecosystem levels may affect stability of alternative stable states in shallow lakes when mediated by fish migration. Migration effects on shallow lakes result from processes at different scales, from the individual to the ecosystem. Our earlier research has shown that ecosystem...

  20. Hydrology and water quality of Shell Lake, Washburn County, Wisconsin, with special emphasis on the effects of diversion and changes in water level on the water quality of a shallow terminal lake

    Science.gov (United States)

    Juckem, Paul F.; Robertson, Dale M.

    2013-01-01

    toward the lake. Total groundwater inflow to Shell Lake is small (approximately 5 percent of the water budget) compared with water entering the lake from precipitation (83 percent) and surface-water runoff (13 percent). The MODFLOW model also was used to simulate average annual hydrologic conditions from 1949 to 2009, including effects of the removal of 3 billion gallons of water during 2003–5. The maximum decline in simulated average annual water levels for Shell Lake due to the diversion alone was 3.3 ft at the end of the diversion process in 2005. Model simulations also indicate that although water level continued to decline through 2009 in response to local weather patterns (local drought), the effects of the diversion decreased after the diversion ceased; that is, after 4 years of recovery (2006–9), drawdown attributable to the diversion alone decreased by about 0.6 ft because of increased groundwater inflow and decreased lake-water outflow to groundwater caused by the artificially lower lake level. A delayed response in drawdown of less than 0.5 ft was transmitted through the groundwater-flow system to upgradient lakes. This relatively small effect on upgradient lakes is attributed in part to extensive layers of shallow clay that limit lake/groundwater interaction in the area. Data collected in the lake indicated that Shell Lake is polymictic (characterized by frequent deep mixing) and that its productivity is limited by the amount of phosphorus in the lake. The lake was typically classified as oligotrophic-mesotrophic in June, mesotrophic in July, and mesotrophic-eutrophic in August. In polymictic lakes like Shell Lake, phosphorus released from the sediments is not trapped near the bottom of the lake but is intermittently released to the shallow water, resulting in deteriorating water quality as summer progresses. Because the productivity of Shell Lake is limited by phosphorus, the sources of phosphorus to the lake were quantified, and the response in water

  1. Halogenated organic contaminants (HOCs) in sediment from a highly eutrophicated lake, China: occurrence, distribution and mass inventories.

    Science.gov (United States)

    Wang, Ji-Zhong; Liu, Liang-Ying; Zhang, Kai; Liang, Bo; Li, Guo-Lian; Chen, Tian-Hu

    2012-11-01

    Halogenated organic contaminants (HOCs) including 16 polybrominated diphenyl ethers (PBDEs) and 37 polychlorinated biphenyls (PCBs) were determined in 49 surfacial sediments from Chaohu Lake, a highly eutrophicated lake, China. PBDEs were detected in almost samples with the range of the total concentration (defined as Σ(16)PBDEs) from 0.84 to 86.6 ng g(-1). Compared with the occurrence of PBDEs in Pearl River Delta and Yangtze River Delta in China, lower percentage of BDE-209 over the concentration of Σ(16)PBDEs was inferred by the high-volume application of penta-BDE mixture product for local domestic furniture purpose. The total concentration of 37 PCBs (Σ(37)PCBs) ranged from 0.05 to 3.36 ng g(-1) with the most detection of PCB-1, -4, -52 and -71. Both the concentrations of Σ(16)PBDE and Σ(37)PCB poorly correlated with total organic carbon (TOC), suggesting the significant contribution of phytoplankton organic carbons to sediment TOC. The contamination by PBDEs and PCBs in western region of the lake was significantly more serious than in eastern lake. Our findings about the higher residues of PBDEs and PCBs in sediments at the estuary of Nanfei River compared to the other estuaries also supported the conclusion that urban area (Hefei city) was the main source of PBDEs and PCBs. The comparison with the concentration of HOC in the present study with those in other lacustrine sediments around the world suggested the contamination by PBDEs in Chaohu Lake is at middle of the global concentration range, whereas PCBs is at low end of the global range which could be elucidated by local economic development and historical usage of PBDEs and PCBs. The mass inventories of HOCs in the lake were estimated at 561 and 38 kg, which corresponds to only 0.000006% and 0.0001% of these global historical produce volumes, respectively. Copyright © 2012 Elsevier Ltd. All rights reserved.

  2. Phytoplankton response to fish-induced environmental changes in a temperate shallow pond-type lake

    Directory of Open Access Journals (Sweden)

    Napiórkowska-Krzebietke Agnieszka

    2017-12-01

    Full Text Available Since 1967, the temperate, shallow, pond-type Lake Warniak has been subjected to different biomanipulation methods including the introduction of common carp, Cyprinus carpio L., grass carp, Ctenopharyngodon idella (Val., silver carp, Hypophthalmichthys molitrix (Val., and bighead carp, Hypophthalmichthys nobilis (Richardson and then their removal in an effort to control macrophytes and phytoplankton. Recently, pilot stocking with predatory fish, particularly pike, Esox lucius L., has also been conducted. Hence, an examination of the long-term response patterns of phytoplankton to multiple fish-induced stressors was undertaken. In recent years, Chara domination (2000-2004 has helped to stabilize a clear-water state, high/good ecological status, and meso-eutrophic conditions. After the disappearance of Charales in 2004, the rapid, unstable changes in phytoplankton biomass, structure, and biodiversity suggested a shift toward a turbid-water state. As a result, the phytoplankton assemblages changed from those dominated by cryptophytes Y+X2+X1+LO (2000-2004 through those dominated by cyanobacteria K (2005-2008, dinoflagellates LO+Y (2009-2011, and cryptophytes Y+LO+F+X2 (2012, to those dominated by diatoms D+K+P+A (2013-2014 with representative taxa that occur in nutrient-rich and/or nutrient-poor water bodies. The 1967-2014 changes indicated that four periods, two with clear-water state and two with turbid-water state, alternately, one after the other, resulted from different fish pressure. Higher autochthonous fish biomass was usually accompanied by lower phytoplankton biomass. In contrast, the introduction of Cyprinidae fish had a stimulating effect on summer phytoplankton dominated by cyanobateria. Among the nutrients, only phosphorus played an important role.

  3. Species composition, abundance and distribution of zooplankton in a tropical eutrophic lake: Lake Catemaco, México

    Directory of Open Access Journals (Sweden)

    Roberto E. Torres-Orozco B.

    1998-06-01

    Full Text Available From April 1992 to May 1993, zooplankton samples were collected monthly by means of horizontal tows in nine sites of the lake. Prior to the towing, temperature of surface water, transparency (Secchi, pH and dissolved oxygen were evaluated. A total of 31 zooplankton forms, including 14 species of rotifers, three copepods, five cladocerans and one ostracod, as well as protozoans (mainly vorticellids and ciliates, were detected. Rotifers were the dominant organisms, mainly Brachionus havanaensis (27.6 ind l-¹, B. angularis (6.9 ind l-¹, Keratella cochlearis (4.9 ind l-¹, Conochilus unicornis (10.8 ind l-¹ and C. dossuarius (3.1 ind l-¹. Within crustaceans, higher densities were shown by larvae (nauplii and copepodites of calanoid (16.8 ind l-¹ and cyclopoid (15.6 ind l-¹ copepods, as well as Arctodiaptomus dorsalis (2 ind l-¹, Mesocyclops edax (0.5 ind l-¹, and the cladocerans Bosmina longirostris (1.6 ind l-¹ and Diaphanosoma brachyurum (0.5 ind l-¹. Densities were low, probably because of a high predation pressure imposed by fishes. A gradual increase in total zooplankton density related with a progressive diminution of transparency was observed throughout the sampling period. Zooplankton densities in the stations located at the central part of the lake were higher when compared with those at a more peripheral position. Time variation in rotifer's relative abundance was directly related to temperature fluctuations. The low density and diversity values, the small size of the zooplankters, the presence of an important number of indicator species, and the calanoid copepods: other planktonic crustaceans low ratio, are all indicators of eutrophy. Evidences suggest that the eutrophication process of Lake Catemaco is still progressing rapidly.Entre abril de 1992 y mayo de 1993, se realizaron mensualmente recolectas subsuperficiales de zooplancton, con red, en nueve localidades del lago, en donde también se determinaron la temperatura

  4. Comparing Effects of Lake- and Watershed-Scale Influences on Communities of Aquatic Invertebrates in Shallow Lakes

    Science.gov (United States)

    Hanson, Mark A.; Herwig, Brian R.; Zimmer, Kyle D.; Fieberg, John; Vaughn, Sean R.; Wright, Robert G.; Younk, Jerry A.

    2012-01-01

    Constraints on lake communities are complex and are usually studied by using limited combinations of variables derived from measurements within or adjacent to study waters. While informative, results often provide limited insight about magnitude of simultaneous influences operating at multiple scales, such as lake- vs. watershed-scale. To formulate comparisons of such contrasting influences, we explored factors controlling the abundance of predominant aquatic invertebrates in 75 shallow lakes in western Minnesota, USA. Using robust regression techniques, we modeled relative abundance of Amphipoda, small and large cladocera, Corixidae, aquatic Diptera, and an aggregate taxon that combined Ephemeroptera-Trichoptera-Odonata (ETO) in response to lake- and watershed-scale characteristics. Predictor variables included fish and submerged plant abundance, linear distance to the nearest wetland or lake, watershed size, and proportion of the watershed in agricultural production. Among-lake variability in invertebrate abundance was more often explained by lake-scale predictors than by variables based on watershed characteristics. For example, we identified significant associations between fish presence and community type and abundance of small and large cladocera, Amphipoda, Diptera, and ETO. Abundance of Amphipoda, Diptera, and Corixidae were also positively correlated with submerged plant abundance. We observed no associations between lake-watershed variables and abundance of our invertebrate taxa. Broadly, our results seem to indicate preeminence of lake-level influences on aquatic invertebrates in shallow lakes, but historical land-use legacies may mask important relationships. PMID:22970275

  5. Circulation induced by diffused aeration in a shallow lake | Toné ...

    African Journals Online (AJOL)

    Field surveys were carried out to investigate the surface jet flows and the resulting circulation patterns generated by diffused aeration in a shallow lake. In conrast to previous studies, the experimental conditions included point-source bubble plumes with very high air flow rates (100–400 L/min) relative to the shallow water ...

  6. Fine sediment dynamics in a shallow lake and implication for design of hydraulic works

    NARCIS (Netherlands)

    Vijverberg, T.; Winterwerp, J.C.; Aarninkhof, S.G.J.; Drost, H.

    2010-01-01

    Lake Markermeer is a large (680 km2), shallow body of water in the middle of the Netherlands, with a mean water depth of 3.6 m. One of the major problems in the lake is its decreasing ecological value which is, among other reasons, caused by a gradual increase of suspended sediment concentration and

  7. Sediment characteristics and wind-induced sediment dynamics in shallow Lake Markermeer, the Netherlands

    NARCIS (Netherlands)

    Kelderman, P.; Ang'weya, R.O.; De Rozari, P.; Vijverberg, T.

    2012-01-01

    In 2007/08, a study was undertaken on the sediment dynamics in shallow Lake Markermeer (the Netherlands). Firstly, sediment characteristics were determined at 49 sites in the lake. Parameters such as median grain size and loss on ignition showed a spatial as well as water depth related pattern,

  8. Multivariate-Analysis of Phytoplankton and Related Environmental-Factors, in a Shallow Hypertrophic Lake

    NARCIS (Netherlands)

    Romo, S.; Van Tongeren, O.F.R.

    1995-01-01

    Data on some relevant environmental variables and phytoplankton species composition, collected from the hypertrophic shallow lake Albufera of Valencia (Spain) during 1980-88, were examined using Redundancy Analysis (RDA). The hydrological cycle of the lake is manipulated for rice cultivation in the

  9. The Potential Applications of Real-Time Monitoring of Water Quality in a Large Shallow Lake (Lake Taihu, China) Using a Chromophoric Dissolved Organic Matter Fluorescence Sensor

    Science.gov (United States)

    Niu, Cheng; Zhang, Yunlin; Zhou, Yongqiang; Shi, Kun; Liu, Xiaohan; Qin, Boqiang

    2014-01-01

    This study presents results from field surveys performed over various seasons in a large, eutrophic, shallow lake (Lake Taihu, China) using an in situ chromophoric dissolved organic matter (CDOM) fluorescence sensor as a surrogate for other water quality parameters. These measurements identified highly significant empirical relationships between CDOM concentration measured using the in situ fluorescence sensor and CDOM absorption, fluorescence, dissolved organic carbon (DOC), chemical oxygen demand (COD) and total phosphorus (TP) concentrations. CDOM concentration expressed in quinine sulfate equivalent units, was highly correlated with the CDOM absorption coefficient (r2 = 0.80, p CDOM concentration measured using the in situ fluorescence sensor could act as a substitute for the CDOM absorption coefficient and fluorescence measured in the laboratory. Similarly, CDOM concentration was highly correlated with DOC concentration (r2 = 0.68, p CDOM fluorescence sensor measurements could be a proxy for DOC concentration. In addition, significant positive correlations were found between laboratory CDOM absorption coefficients and COD (r2 = 0.83, p CDOM fluorescence sensor. PMID:24984060

  10. The potential applications of real-time monitoring of water quality in a large shallow lake (Lake Taihu, China) using a chromophoric dissolved organic matter fluorescence sensor.

    Science.gov (United States)

    Niu, Cheng; Zhang, Yunlin; Zhou, Yongqiang; Shi, Kun; Liu, Xiaohan; Qin, Boqiang

    2014-06-30

    This study presents results from field surveys performed over various seasons in a large, eutrophic, shallow lake (Lake Taihu, China) using an in situ chromophoric dissolved organic matter (CDOM) fluorescence sensor as a surrogate for other water quality parameters. These measurements identified highly significant empirical relationships between CDOM concentration measured using the in situ fluorescence sensor and CDOM absorption, fluorescence, dissolved organic carbon (DOC), chemical oxygen demand (COD) and total phosphorus (TP) concentrations. CDOM concentration expressed in quinine sulfate equivalent units, was highly correlated with the CDOM absorption coefficient (r(2) = 0.80, p CDOM concentration measured using the in situ fluorescence sensor could act as a substitute for the CDOM absorption coefficient and fluorescence measured in the laboratory. Similarly, CDOM concentration was highly correlated with DOC concentration (r(2) = 0.68, p CDOM fluorescence sensor measurements could be a proxy for DOC concentration. In addition, significant positive correlations were found between laboratory CDOM absorption coefficients and COD (r(2) = 0.83, p CDOM fluorescence sensor.

  11. The distribution of chydorids (Branchiopoda, Anomopoda)in European shallow lakes and its application to ecological quality monitoring

    NARCIS (Netherlands)

    Eyto, de E.; Irvine, K.; Garcia-Criado, F.; Gyllström, M.; Jeppesen, E.; Kornijow, R.; Miracle, M.R.; Nykänen, M.; Bareiss, C.; Cerbin, S.; Salujoe, J.; Franken, R.J.M.; Stephens, D.; Moss, B.

    2003-01-01

    This study describes the chydorid (Branchiopoda, Anomopoda) assemblages from 66 European shallow lakes, and presents data relating the assemblages to lake type and ecological quality
    This study describes the chydorid (Branchiopoda, Anomopoda) assemblages from 66 European shallow lakes, and

  12. Mitigation of eutrophication in river basins, lakes, and coastal waters requires and integrated and adaptive approach; experiences from The Netherlands.

    Science.gov (United States)

    Rozemeijer, J.; Jansen, S.; Villars, N.; Grift, B. V. D.

    2017-12-01

    We propose a guideline for mitigation of eutrophication in river basins, lakes, and coastal waters. The proposed strategy is based on our experiences with implementation of manure legislation and the Water Framework Directive (WFD) in Europe. These regulations led to reduced nutrient losses from highly productive agricultural areas. For example in The Netherlands, the worldwide second largest exporter of agricultural products, nutrient concentrations in agricultural headwaters reduced since the early 1990's. Our guideline builds on three basic principles: (1) a conceptual framework integrating water quality, water quantity, soil, groundwater, and surface water, (2) the `from catchment to coast' approach for up-scaling field-scale pilot results to downstream ecological effects, and (3) a mitigation order of preference from (a) optimizing nutrient uptake efficiency to (b) enhancing nutrient retention and recirculation to (c) nutrient discharge and applying effect oriented measures. The tools needed to mitigate eutrophication are system understanding, smart monitoring, smart modelling, smart measures, and smart governance. Following these principles and using these tools enables an integrated, adaptive approach for selecting, implementing, and evaluating the most cost-effective and sustainable set of mitigation actions.

  13. Tracking past changes in lake-water phosphorus with a 251-lake calibration dataset in British Columbia: tool development and application in a multiproxy assessment of eutrophication and recovery in Osoyoos Lake, a transboundary lake in western North America

    Directory of Open Access Journals (Sweden)

    Brian Fraser Cumming

    2015-08-01

    Full Text Available Recently there has been an active discussion about the potential and challenges of tracking past lake-water trophic state using paleolimnological methods. Herein, we present analyses of the relationship between modern-day diatom assemblages from the surface sediments of 251 fresh-water lakes from British Columbia and contemporary limnological variables. Total phosphorus (TP was significantly related to the modern distribution of diatom assemblages. The large size of this new calibration dataset resulted in higher abundances and occurrences of many diatom taxa thereby allowing a more accurate quantification of the optima of diatom taxa to TP in comparison to previous smaller calibration datasets. Robust diatom-based TP inference models with a moderate predictive power were developed using weighted-averaging regression and calibration. Information from the calibration dataset was used to interpret changes in the diatom assemblages from the north and south basins of Osoyoos Lake, in conjunction with fossil pigment analyses. Osoyoos Lake is a large salmon-bearing lake that straddles the British Columbia-Washington border and has undergone cultural eutrophication followed by recovery due to substantial mitigation efforts in managing sources of nutrients. Both diatom assemblages and sedimentary pigments indicate that eutrophication began c. 1950 in the north basin and c. 1960 in the southern basin, reaching peak levels of production between 1960 and 1990, after which decreases in sedimentary pigments occurred, as well as decreases in the relative abundance and concentrations of diatom taxa inferred to have high TP optima. Post-1990 changes in the diatom assemblage suggests conditions have become less productive with a shift to taxa more indicative of lower TP optima in concert with measurements of declining TP, two of these diatom taxa, Cyclotella comensis and Cyclotella gordonensis, that were previously rare are now abundant.

  14. Climate Change Will Make Recovery from Eutrophication More Difficult in Shallow Danish Lake Søbygaard

    DEFF Research Database (Denmark)

    Rolighed, Jonas; Jeppesen, Erik; Søndergaard, Martin

    2016-01-01

    . The nutrient loading reduction scenarios predicted increased diatom dominance, accompanied by an increase in the zooplankton:phytoplankton biomass ratio. Simulations generally showed phytoplankton to benefit from a warmer climate and the fraction of cyanobacteria to increase. In the 6 ◦C warming scenario...

  15. Light climate and its impact on Potamogeton pectinatus L. in a shallow eutrophic lake

    NARCIS (Netherlands)

    Dijk, van G.M.

    1991-01-01

    Eutrofiëring, dat wil zeggen een toename in aanbod van nutriënten, vormt de laatste decennia een van de belangrijkste bedreigingen voor aquatische ecosystemen in zoete, brakke en mariene wateren. Bij eutrofiëring profiteren de waterplanten, de planktonische en de epifytische algen van het toegenomen

  16. Threshold sensitivity of shallow Arctic lakes and sublake permafrost to changing winter climate

    Science.gov (United States)

    Arp, Christopher D.; Jones, Benjamin M.; Grosse, Guido; Bondurant, Allen C.; Romanovksy, Vladimir E.; Hinkel, Kenneth M.; Parsekian, Andrew D.

    2016-01-01

    Interactions and feedbacks between abundant surface waters and permafrost fundamentally shape lowland Arctic landscapes. Sublake permafrost is maintained when the maximum ice thickness (MIT) exceeds lake depth and mean annual bed temperatures (MABTs) remain below freezing. However, declining MIT since the 1970s is likely causing talik development below shallow lakes. Here we show high-temperature sensitivity to winter ice growth at the water-sediment interface of shallow lakes based on year-round lake sensor data. Empirical model experiments suggest that shallow (1 m depth) lakes have warmed substantially over the last 30 years (2.4°C), with MABT above freezing 5 of the last 7 years. This is in comparison to slower rates of warming in deeper (3 m) lakes (0.9°C), with already well-developed taliks. Our findings indicate that permafrost below shallow lakes has already begun crossing a critical thawing threshold approximately 70 years prior to predicted terrestrial permafrost thaw in northern Alaska.

  17. Challenge to the model of lake charr evolution: Shallow- and deep-water morphs exist within a small postglacial lake

    Science.gov (United States)

    Chavarie, Louise; Muir, Andrew M.; Zimmerman, Mara S.; Baillie, Shauna M.; Hansen, Michael J.; Nate, Nancy A.; Yule, Daniel L.; Middel, Trevor; Bentzen, Paul; Krueger, Charles C.

    2016-01-01

    All examples of lake charr (Salvelinus namaycush) diversity occur within the largest, deepest lakes of North America (i.e. > 2000 km2). We report here Rush Lake (1.3 km2) as the first example of a small lake with two lake charr morphs (lean and huronicus). Morphology, diet, life history, and genetics were examined to demonstrate the existence of morphs and determine the potential influence of evolutionary processes that led to their formation or maintenance. Results showed that the huronicus morph, caught in deep-water, had a deeper body, smaller head and jaws, higher eye position, greater buoyancy, and deeper peduncle than the shallow-water lean morph. Huronicus grew slower to a smaller adult size, and had an older mean age than the lean morph. Genetic comparisons showed low genetic divergence between morphs, indicating incomplete reproductive isolation. Phenotypic plasticity and differences in habitat use between deep and shallow waters associated with variation in foraging opportunities seems to have been sufficient to maintain the two morphs, demonstrating their important roles in resource polymorphism. Rush Lake expands previous explanations for lake charr intraspecific diversity, from large to small lakes and from reproductive isolation to the presence of gene flow associated with strong ecological drivers.

  18. Carbon source/sink function of a subtropical, eutrophic lake determined from an overall mass balance and a gas exchange and carbon burial balance

    International Nuclear Information System (INIS)

    Yang Hong; Xing Yangping; Xie Ping; Ni Leyi; Rong Kewen

    2008-01-01

    Although studies on carbon burial in lake sediments have shown that lakes are disproportionately important carbon sinks, many studies on gaseous carbon exchange across the water-air interface have demonstrated that lakes are supersaturated with CO 2 and CH 4 causing a net release of CO 2 and CH 4 to the atmosphere. In order to more accurately estimate the net carbon source/sink function of lake ecosystems, a more comprehensive carbon budget is needed, especially for gaseous carbon exchange across the water-air interface. Using two methods, overall mass balance and gas exchange and carbon burial balance, we assessed the carbon source/sink function of Lake Donghu, a subtropical, eutrophic lake, from April 2003 to March 2004. With the overall mass balance calculations, total carbon input was 14 905 t, total carbon output was 4950 t, and net carbon budget was +9955 t, suggesting that Lake Donghu was a great carbon sink. For the gas exchange and carbon burial balance, gaseous carbon (CO 2 and CH 4 ) emission across the water-air interface totaled 752 t while carbon burial in the lake sediment was 9477 t. The ratio of carbon emission into the atmosphere to carbon burial into the sediment was only 0.08. This low ratio indicates that Lake Donghu is a great carbon sink. Results showed good agreement between the two methods with both showing Lake Donghu to be a great carbon sink. This results from the high primary production of Lake Donghu, substantive allochthonous carbon inputs and intensive anthropogenic activity. Gaseous carbon emission accounted for about 15% of the total carbon output, indicating that the total output would be underestimated without including gaseous carbon exchange. - Due to high primary production, substantive allochthonous carbon inputs and intensive anthropogenic acitivity, subtropical, eutrophic Lake Donghu is a great carbon sink

  19. Bacterial community composition of size-fractioned aggregates within the phycosphere of cyanobacterial blooms in a eutrophic freshwater lake.

    Directory of Open Access Journals (Sweden)

    Haiyuan Cai

    Full Text Available Bacterial community composition of different sized aggregates within the Microcystis cyanobacterial phycosphere were determined during summer and fall in Lake Taihu, a eutrophic lake in eastern China. Bloom samples taken in August and September represent healthy bloom biomass, whereas samples from October represent decomposing bloom biomass. To improve our understanding of the complex interior structure in the phycosphere, bloom samples were separated into large (>100 µm, medium (10-100 µm and small (0.2-10 µm size aggregates. Species richness and library coverage indicated that pyrosequencing recovered a large bacterial diversity. The community of each size aggregate was highly organized, indicating highly specific conditions within the Microcystis phycosphere. While the communities of medium and small-size aggregates clustered together in August and September samples, large- and medium-size aggregate communities in the October sample were grouped together and distinct from small-size aggregate community. Pronounced changes in the absolute and relative percentages of the dominant genus from the two most important phyla Proteobacteria and Bacteroidetes were observed among the various size aggregates. Bacterial species on large and small-size aggregates likely have the ability to degrade high and low molecular weight compounds, respectively. Thus, there exists a spatial differentiation of bacterial taxa within the phycosphere, possibly operating in sequence and synergy to catalyze the turnover of complex organic matters.

  20. Potential human health risks from metals and As via Odontesthes bonariensis consumption and ecological risk assessments in a eutrophic lake.

    Science.gov (United States)

    Monferran, Magdalena V; Garnero, Paola Lorena; Wunderlin, Daniel A; Bistoni, María de los Angeles

    2016-07-01

    The concentration of Al, Cr, Fe, Mn, Ni, Cu, Zn, Hg, Sr, Mo, Ag, Cd, Pb and As was analyzed in water, sediment, and muscle of Odontesthes bonariensis from the eutrophic San Roque Lake (Córdoba-Argentina). The monitoring campaign was performed during the wet, dry and intermediate season. The concentration of Cr, Fe, Pb, Zn, Al and Cd in water exceeded the limits considered as hazardous for aquatic life. The highest metal concentrations were observed in sediment, intermediate concentrations, in fish muscle, and the lowest in water, with the exception of Cr, Zn, As and Hg, which were the highest in fish muscle. Potential ecological risk analysis of heavy metal concentrations in sediment indicated that the San Roque Lake posed a low ecological risk in all sampling periods. The target hazard quotients (THQs) and carcinogenic risk (CR) for individual metals showed that As in muscle was particularly hazardous, posing a potential risk for fishermen and the general population during all sampling periods. Hg poses a potential risk for fishermen only in the intermediate season. It is important to highlight that none of these two elements exceeded the limits considered as hazardous for aquatic life in water and sediment. This result proves the importance of performing measurements of contaminants, in both abiotic and biotic compartments, to assess the quality of food resources. These results suggest that the consumption of this fish species from this reservoir is not completely safe for human health. Copyright © 2016 Elsevier Inc. All rights reserved.

  1. Optical properties and composition changes in chromophoric dissolved organic matter along trophic gradients: Implications for monitoring and assessing lake eutrophication.

    Science.gov (United States)

    Zhang, Yunlin; Zhou, Yongqiang; Shi, Kun; Qin, Boqiang; Yao, Xiaolong; Zhang, Yibo

    2017-12-26

    Chromophoric dissolved organic matter (CDOM) is an important optically active substance in aquatic environments and plays a key role in light attenuation and in the carbon, nitrogen and phosphorus biogeochemical cycles. Although the optical properties, abundance, sources, cycles, compositions and remote sensing estimations of CDOM have been widely reported in different aquatic environments, little is known about the optical properties and composition changes in CDOM along trophic gradients. Therefore, we collected 821 samples from 22 lakes along a trophic gradient (oligotrophic to eutrophic) in China from 2004 to 2015 and determined the CDOM spectral absorption and nutrient concentrations. The total nitrogen (TN), total phosphorus (TP), and chlorophyll a (Chla) concentrations and the Secchi disk depth (SDD) ranged from 0.02 to 24.75 mg/L, 0.002-3.471 mg/L, 0.03-882.66 μg/L, and 0.05-17.30 m, respectively. The trophic state index (TSI) ranged from 1.55 to 98.91 and covered different trophic states, from oligotrophic to hyper-eutrophic. The CDOM absorption coefficient at 254 nm (a(254)) ranged from 1.68 to 92.65 m -1 . Additionally, the CDOM sources and composition parameters, including the spectral slope and relative molecular size value, exhibited a substantial variability from the oligotrophic level to other trophic levels. The natural logarithm value of the CDOM absorption, lna(254), is highly linearly correlated with the TSI (r 2  = 0.92, p 10 m -1 , respectively. The results suggested that the CDOM absorption coefficient a(254) might be a more sensitive single indicator of the trophic state than TN, TP, Chla and SDD. Therefore, we proposed a CDOM absorption coefficient and determined the threshold for defining the trophic state of a lake. Several advantages of measuring and estimating CDOM, including rapid experimental measurements, potential in situ optical sensor measurements and large-spatial-scale remote sensing estimations, make it

  2. Uncovering state-dependent relationships in shallow lakes using Bayesian latent variable regression.

    Science.gov (United States)

    Vitense, Kelsey; Hanson, Mark A; Herwig, Brian R; Zimmer, Kyle D; Fieberg, John

    2018-03-01

    Ecosystems sometimes undergo dramatic shifts between contrasting regimes. Shallow lakes, for instance, can transition between two alternative stable states: a clear state dominated by submerged aquatic vegetation and a turbid state dominated by phytoplankton. Theoretical models suggest that critical nutrient thresholds differentiate three lake types: highly resilient clear lakes, lakes that may switch between clear and turbid states following perturbations, and highly resilient turbid lakes. For effective and efficient management of shallow lakes and other systems, managers need tools to identify critical thresholds and state-dependent relationships between driving variables and key system features. Using shallow lakes as a model system for which alternative stable states have been demonstrated, we developed an integrated framework using Bayesian latent variable regression (BLR) to classify lake states, identify critical total phosphorus (TP) thresholds, and estimate steady state relationships between TP and chlorophyll a (chl a) using cross-sectional data. We evaluated the method using data simulated from a stochastic differential equation model and compared its performance to k-means clustering with regression (KMR). We also applied the framework to data comprising 130 shallow lakes. For simulated data sets, BLR had high state classification rates (median/mean accuracy >97%) and accurately estimated TP thresholds and state-dependent TP-chl a relationships. Classification and estimation improved with increasing sample size and decreasing noise levels. Compared to KMR, BLR had higher classification rates and better approximated the TP-chl a steady state relationships and TP thresholds. We fit the BLR model to three different years of empirical shallow lake data, and managers can use the estimated bifurcation diagrams to prioritize lakes for management according to their proximity to thresholds and chance of successful rehabilitation. Our model improves upon

  3. Multi-sensor satellite and in situ monitoring of phytoplankton development in a eutrophic-mesotrophic lake.

    Science.gov (United States)

    Dörnhöfer, Katja; Klinger, Philip; Heege, Thomas; Oppelt, Natascha

    2018-01-15

    Phytoplankton indicated by its photosynthetic pigment chlorophyll-a is an important pointer on lake ecology and a regularly monitored parameter within the European Water Framework Directive. Along with eutrophication and global warming cyanobacteria gain increasing importance concerning human health aspects. Optical remote sensing may support both the monitoring of horizontal distribution of phytoplankton and cyanobacteria at the lake surface and the reduction of spatial uncertainties associated with limited water sample analyses. Temporal and spatial resolution of using only one satellite sensor, however, may constrain its information value. To discuss the advantages of a multi-sensor approach the sensor-independent, physically based model MIP (Modular Inversion and Processing System) was applied at Lake Kummerow, Germany, and lake surface chlorophyll-a was derived from 33 images of five different sensors (MODIS-Terra, MODIS-Aqua, Landsat 8, Landsat 7 and Sentinel-2A). Remotely sensed lake average chlorophyll-a concentration showed a reasonable development and varied between 2.3±0.4 and 35.8±2.0mg·m -3 from July to October 2015. Match-ups between in situ and satellite chlorophyll-a revealed varying performances of Landsat 8 (RMSE: 3.6 and 19.7mg·m -3 ), Landsat 7 (RMSE: 6.2mg·m -3 ), Sentinel-2A (RMSE: 5.1mg·m -3 ) and MODIS (RMSE: 12.8mg·m -3 ), whereas an in situ data uncertainty of 48% needs to be respected. The temporal development of an index on harmful algal blooms corresponded well with the cyanobacteria biomass development during summer months. Satellite chlorophyll-a maps allowed to follow spatial patterns of chlorophyll-a distribution during a phytoplankton bloom event. Wind conditions mainly explained spatial patterns. Integrating satellite chlorophyll-a into trophic state assessment resulted in different trophic classes. Our study endorsed a combined use of satellite and in situ chlorophyll-a data to alleviate weaknesses of both approaches and

  4. Toxic cyanobacteria in the lakes located in R- lga (the capital of ...

    African Journals Online (AJOL)

    the capital of Latvia) were investigated between 1998 and 2004. These lakes are shallow eutrophic water bodies with a high surface to depth ratio and are widely used for recreational and fishing activities. Intense cyanobacterial blooms were ...

  5. Restoring lakes by using artificial plant beds: habitat selection of zooplankton in a clear and a turbid shallow lake

    DEFF Research Database (Denmark)

    Schou, Majbritt Overgård; Risholt, Casper; Lauridsen, Torben L.

    2009-01-01

    1. Return of large-bodied zooplankton populations is of key importance for creating a shift from a turbid to a clear-water state in shallow lakes after a nutrient loading reduction. In temperate lakes, recovery is promoted by submerged macrophytes which function as a daytime refuge for large...... zooplankton. However, recovery of macrophytes is often delayed and use of artificial plant beds (APB) has been suggested as a tool to enhance zooplankton refuges, thereby reinforcing the shift to a clear-water state and, eventually, colonisation of natural plants. 2. To further evaluate the potential of APB...... in lake restoration, we followed the day–night habitat choices of zooplankton throughout summer in a clear and a turbid lake. Observations were made in the pelagic and littoral zones and in APB in the littoral representing three different plant densities (coverage 0%, 40% and 80%). 3. In the clear lake...

  6. Hydroacoustic estimates of fish biomass and spatial distributions in shallow lakes

    Science.gov (United States)

    Lian, Yuxi; Huang, Geng; Godlewska, Małgorzata; Cai, Xingwei; Li, Chang; Ye, Shaowen; Liu, Jiashou; Li, Zhongjie

    2018-03-01

    We conducted acoustical surveys with a horizontal beam transducer to detect fish and with a vertical beam transducer to detect depth and macrophytes in two typical shallow lakes along the middle and lower reaches of the Changjiang (Yangtze) River in November 2013. Both lakes are subject to active fish management with annual stocking and removal of large fish. The purpose of the study was to compare hydroacoustic horizontal beam estimates with fish landings. The preliminary results show that the fish distribution patterns differed in the two lakes and were affected by water depth and macrophyte coverage. The hydroacoustically estimated fish biomass matched the commercial catch very well in Niushan Lake, but it was two times higher in Kuilei Lake. However, acoustic estimates included all fish, whereas the catch included only fish >45 cm (smaller ones were released). We were unable to determine the proper regression between acoustic target strength and fish length for the dominant fish species in the two lakes.

  7. Utilization of satellite images to understand the dynamics of Pampas shallow lakes

    Directory of Open Access Journals (Sweden)

    V. S. Aliaga

    2016-06-01

    Full Text Available The aim of this study was to analyze satellite images of different spatial resolutions to interpret the morphometric behavior of six shallow lakes of the Pampas, Argentina. These are characterized by having different rainfall regimes. Morphometric response considering each location, site conditions and dry and wet extreme events is analyzed. Standardized Precipitation Index (IEP for determination of wet, dry and normal years was used. This analysis showed that the Pampas shallow lakes do not behave in the same way to the rainfall events. Its origin, socio-economic use and rainfall patterns affect their spatiotemporal variation and morphometric.

  8. Bacterial diversity and geochemical profiles in sediments from eutrophic Azorean lakes

    NARCIS (Netherlands)

    da Costa Martins, G.; Henriques, I.; Ribeiro, D.C; Correia, A.; Bodelier, P.L.E.; Cruz, J.V.; Brito, A.G.; Nogueira, R.

    2012-01-01

    In the Azores, the advanced trophic state of the lakes requires a fast intervention to achieve the good ecological status prescribed by the Water Framework Directive. Despite the considerable effort made to describe the phytoplankton growing on the water column, the lack of information regarding the

  9. Determining Long-Term Trends of Four Fast-Eutrophicated Lakes in China and Finland

    DEFF Research Database (Denmark)

    Liao, Mengna; Yu, Ge; Ventelä, Anne-Mari

    2016-01-01

    by increases in tourism, farming and urbanization respectively. Water quality changes in Lakes Lugu, Taibai and Taihu captured 68.4%, 54.9%, and 86.0% of the temperature variations before the turning points. The anthropogenic impacts explained 84.0%, 96.4% and 96.0% of the water quality variations after...

  10. Bioelectrode-based approach for enhancing nitrate and nitrite removal and electricity generation from eutrophic lakes

    DEFF Research Database (Denmark)

    Zhang, Yifeng; Angelidaki, Irini

    2012-01-01

    Nitrate and nitrite contamination of surface waters (e.g. lakes) has become a severe environmental and health problem, especially in developing countries. The recent demonstration of nitrate reduction at the cathode of microbial fuel cell (MFC) provides an opportunity to develop a new technology ...

  11. Influence of a carp invasion on the zooplankton community in Laguna Medina, a Mediterranean shallow lake

    OpenAIRE

    Norbert, Florian; López-Luque, raquel; Ospina-Álvarez, Natalia; Hufnagel, Levente; Green, Andy J.

    2016-01-01

    The common carp (Cyprinus carpio) is a highly invasive species and an ecological engineer. It has been repeatedly shown to increase nutrient concentrations and phytoplankton biomass while destroying submerged macrophytes, although there are few studies from the Mediterranean region. We studied its impact on the zooplankton community in Laguna de Medina lake, a shallow lake in Jerez de la Frontera, south-west Spain. Carp were removed with rotenone in 2007 but returned in 2010-2011. ...

  12. Shallow and deep controls on lava lake surface motion at Kīlauea Volcano

    Science.gov (United States)

    Patrick, Matthew R.; Orr, Tim R.; Swanson, Don; Lev, Einat

    2016-01-01

    Lava lakes provide a rare window into magmatic behavior, and lake surface motion has been used to infer deeper properties of the magmatic system. At Halema'uma'u Crater, at the summit of Kīlauea Volcano, multidisciplinary observations for the past several years indicate that lava lake surface motion can be broadly divided into two regimes: 1) stable and 2) unstable. Stable behavior is driven by lava upwelling from deeper in the lake (presumably directly from the conduit) and is an intrinsic process that drives lava lake surface motion most of the time. This stable behavior can be interrupted by periods of unstable flow (often reversals) driven by spattering – a shallowly-rooted process often extrinsically triggered by small rockfalls from the crater wall. The bursting bubbles at spatter sources create void spaces and a localized surface depression which draws and consumes surrounding surface crust. Spattering is therefore a location of lava downwelling, not upwelling. Stable (i.e. deep, upwelling-driven) and unstable (i.e. shallow, spattering-driven) behavior often alternate through time, have characteristic surface velocities, flow directions and surface temperature regimes, and also correspond to changes in spattering intensity, outgassing rates, lava level and seismic tremor. These results highlight that several processes, originating at different depths, can control the motion of the lava lake surface, and long-term interdisciplinary monitoring is required to separate these influences. These observations indicate that lake surface motion is not always a reliable proxy for deeper lake or magmatic processes. From these observations, we suggest that shallow outgassing (spattering), not lake convection, drives the variations in lake motion reported at Erta 'Ale lava lake.

  13. Bioelectrode-based approach for enhancing nitrate and nitrite removal and electricity generation from eutrophic lakes

    DEFF Research Database (Denmark)

    Zhang, Yifeng; Angelidaki, Irini

    Nitrate and nitrite contamination of surface waters (e.g. lakes) has become a severe environmental and health problem, especially in developing countries. The recent demonstration of nitrate reduction at the cathode of microbial fuel cell (MFC) provides an opportunity to develop a new technology...... from nitrate- and nitrite-rich synthetic lake waters at initial concentration of 10 mg-N/L. Along with the electricity production a total nitrogen removal of 62% and 77% was accomplished, for nitrate and nitrite, respectively. The nitrogen removal was almost 4 times higher under close-circuit condition...... with biocathode, compared to either the open-circuit operation or with abiotic cathode. The mass balance on nitrogen indicates that most of the removed nitrate and nitrite (84.7±0.1% and 81.8±0.1%, respectively) was reduced to nitrogen gas. The nitrogen removal and power generation was limited by the dissolved...

  14. A 200 year sedimentary record of progressive eutrophication in lake Greifen (Switzerland): Implications for the origin of organic-carbon-rich sediments

    Science.gov (United States)

    Hollander, David J.; McKenzie, Judith A.; Lo Ten Haven, H.

    1992-09-01

    Over the past 200 years Lake Greifen, a small lake in northeastern Switzerland, has undergone dramatic changes in primary productivity and eutrophication due to increased nutrient supply from agricultural activity and industrialization. A 40 year historical record of the water-column chemistry indicates that productivity and eutrophication reached a maximum in 1974, after which stricter regulations on the input of nutrients resulted in a progressive decrease. Collected cores show the sedimentary expression of this anthropogenically induced eutrophication by a well-developed annual sedimentation and by enhanced values of total organic carbon, organic-carbon accumulation rates, and hydrogen indices (HI) of the kerogens. Analyses of the carbon isotopic composition of sedimentary carbonates and organic matter reveal that the fractionation between these two phases varies with the HI of kerogens. This observation is explicable in terms of changing productivity and preservation of the organic matter, and the CO2(aq) budget of the water body. We propose that if high primary productivity were primarily responsible for the preservation and accumulation of organic matter, then a negative correlation will occur between Δδ13Ccalcite-organic matter (Δδ13Ccal-om) and HI values. In an environment with relatively low to moderate productivity but with bottom-water anoxia, a positive correlation will exist between Δδ13Ccal-om and HI values. This study of Lake Greifen has implications for understanding paleoenvironmental controls on ancient organic-carbon-rich sediments.

  15. Species composition, abundance and distribution of zooplankton in a tropical eutrophic lake: Lake Catemaco, México

    OpenAIRE

    Roberto E. Torres-Orozco B.; Sandra A. Zanatta

    1998-01-01

    From April 1992 to May 1993, zooplankton samples were collected monthly by means of horizontal tows in nine sites of the lake. Prior to the towing, temperature of surface water, transparency (Secchi), pH and dissolved oxygen were evaluated. A total of 31 zooplankton forms, including 14 species of rotifers, three copepods, five cladocerans and one ostracod, as well as protozoans (mainly vorticellids and ciliates), were detected. Rotifers were the dominant organisms, mainly Brachionus havanaens...

  16. Seasonal Trophic Shift of Littoral Consumers in Eutrophic Lake Taihu (China Revealed by a Two-Source Mixing Model

    Directory of Open Access Journals (Sweden)

    Qiong Zhou

    2011-01-01

    Full Text Available We evaluated the seasonal variation in the contributions of planktonic and benthic resources to 11 littoral predators in eutrophic Lake Taihu (China from 2004 to 2005. Seasonal fluctuations in consumer σ13C and σ15N were attributed to the combined impacts of temporal variation in isotopic signatures of basal resources and the diet shift of fishes. Based on a two-end-member mixing model, all target consumers relied on energy sources from coupled benthic and planktonic pathways, but the predominant energy source for most species was highly variable across seasons, showing seasonal trophic shift of littoral consumers. Seasonality in energy mobilization of consumers focused on two aspects: (1 the species number of consumers that relied mainly on planktonic carbon showed the lowest values in the fall and the highest during spring/summer, and (2 most consumer species showed seasonal variation in the percentages of planktonic reliance. We concluded that seasonal trophic shifts of fishes and invertebrates were driven by phytoplankton production, but benthic resources were also important seasonally in supporting littoral consumers in Meiliang Bay. Energy mobilization of carnivorous fishes was more subject to the impact of resource availability than omnivorous species.

  17. Multi-Elements in Waters and Sediments of Shallow Lakes: Relationships with Water, Sediment, and Watershed Characteristics.

    Science.gov (United States)

    Kissoon, La Toya T; Jacob, Donna L; Hanson, Mark A; Herwig, Brian R; Bowe, Shane E; Otte, Marinus L

    2015-06-01

    We measured concentrations of multiple elements, including rare earth elements, in waters and sediments of 38 shallow lakes of varying turbidity and macrophyte cover in the Prairie Parkland (PP) and Laurentian Mixed Forest (LMF) provinces of Minnesota. PP shallow lakes had higher element concentrations in waters and sediments compared to LMF sites. Redundancy analysis indicated that a combination of site- and watershed-scale features explained a large proportion of among-lake variability in element concentrations in lake water and sediments. Percent woodland cover in watersheds, turbidity, open water area, and macrophyte cover collectively explained 65.2 % of variation in element concentrations in lake waters. Sediment fraction smaller than 63 µm, percent woodland in watersheds, open water area, and sediment organic matter collectively explained 64.2 % of variation in element concentrations in lake sediments. In contrast to earlier work on shallow lakes, our results showed the extent to which multiple elements in shallow lake waters and sediments were influenced by a combination of variables including sediment characteristics, lake morphology, and percent land cover in watersheds. These results are informative because they help illustrate the extent of functional connectivity between shallow lakes and adjacent lands within these lake watersheds.

  18. Distribution of metals in fauna, flora and sediments of wet detention ponds and natural shallow lakes

    DEFF Research Database (Denmark)

    Stephansen, D.A.; Nielsen, A.H.; Hvitved-Jacobsen, T.

    2014-01-01

    Fauna, flora, and sediment were collected from 9 wet detention ponds receiving stormwater runoff and 11 small natural shallow lakes. The fauna and flora samples were sorted into species or groups of species and, together with sediments, analyzed for aluminum, copper, iron, zinc, arsenic, cadmium,...

  19. The structuring role of submerged macrophytes in a large subtropical shallow lake

    NARCIS (Netherlands)

    Finkler Ferreira, Tiago; Crossetti, Luciane O.; Motta Marques, David M.L.; Cardoso, Luciana; Fragoso, Carlos Ruberto; Nes, van Egbert H.

    2018-01-01

    It is well known that submerged macrophytes exert positive feedback effects that enhance the water transparency, stabilizing the clear-water state in shallow temperate lakes. However, the structuring effect of macrophytes on the food web of subtropical and tropical ecosystems is still poorly

  20. Littoral zones in shallow lakes. Contribution to water quality in relation to water level regime

    NARCIS (Netherlands)

    Sollie, S.

    2007-01-01

    Littoral zones with emergent vegetation are very narrow or even lacking in Dutch shallow lakes due to a combination of changed water level regime and unfavorable shore morphometry. These zones are important as a habitat for plants and animals, increasing species diversity. It has also been

  1. Shallow lake economics run deep: Nonlinear aspects of an economic-ecological interest conflict

    NARCIS (Netherlands)

    Wagener, F.

    2013-01-01

    Outcomes of the shallow lake long-term interest conflict in a number of different settings are presented, in particular in the contexts of quasi-static and dynamic social planning and of quasi-static non-cooperative play. Also the effect of trigger strategies in repeated quasi-static play is

  2. Shallow lake economics run deep: nonlinear aspects of an economic-ecological interest conflict

    NARCIS (Netherlands)

    Wagener, F.

    2009-01-01

    Outcomes of the shallow lake interest conflict are presented in a number of different contexts: quasi-static and dynamic social planning, and quasi-static one-shot and repeated non-cooperative play. As the underlying dynamics are non-convex, the analysis uses geometrical-numerical methods: the

  3. Spatio-temporal changes in water quality in an eutrophic lake with artificial aeration

    Directory of Open Access Journals (Sweden)

    Ferral Anabella

    2017-12-01

    Full Text Available In this work we present novel results concerning water quality changes in an eutrophic water body connected with an artificial aeration system installed in it. Sixty one in-situ and laboratory measurements of biogeochemical variables were recorded monthly between October 2008 and June 2011 to evaluate temporal and spatial changes in San Roque reservoir (Argentina. t-Student mean difference tests, carried out over the whole period, showed with 95% confidence that a monitoring point located at the centre of the water body is representative of the chemical behaviour of the reservoir. Thermal stratification was observed in all sampling sites in the summer, but the frequency of these episodes was markedly lower in bubbling zones. Mean chlorophyll-a concentrations were 58.9 μg·dm−3 and 117.0 μg·dm−3 in the absence and in the presence of thermocline respectively. According to the t-Student test, this difference was significant, with p < 0.001. Phosphate release from sediments was corroborated under hypoxia conditions. ANOVA one way analysis did not show significant spatial differences for any variable. Mean normalize spatial index (MENSI was developed to compare data from different regions affected by high temporal variability. It proved to be useful to quantify spatial differences. Structure analysis of temporal series was used to scrutinize both chemical and spatial association successfully. Three chemically different zones were determined in the reservoir. This study demonstrated that spatial comparisons by means of marginal statistics may not be an adequate method when high temporal variation is present. In such a case, temporal structure analysis has to be considered.

  4. The Potential Applications of Real-Time Monitoring of Water Quality in a Large Shallow Lake (Lake Taihu, China Using a Chromophoric Dissolved Organic Matter Fluorescence Sensor

    Directory of Open Access Journals (Sweden)

    Cheng Niu

    2014-06-01

    Full Text Available This study presents results from field surveys performed over various seasons in a large, eutrophic, shallow lake (Lake Taihu, China using an in situ chromophoric dissolved organic matter (CDOM fluorescence sensor as a surrogate for other water quality parameters. These measurements identified highly significant empirical relationships between CDOM concentration measured using the in situ fluorescence sensor and CDOM absorption, fluorescence, dissolved organic carbon (DOC, chemical oxygen demand (COD and total phosphorus (TP concentrations. CDOM concentration expressed in quinine sulfate equivalent units, was highly correlated with the CDOM absorption coefficient (r2 = 0.80, p < 0.001, fluorescence intensities (Ex./Em. 370/460 nm (r2 = 0.91, p < 0.001, the fluorescence index (r2 = 0.88, p < 0.001 and the humification index (r2 = 0.78, p < 0.001, suggesting that CDOM concentration measured using the in situ fluorescence sensor could act as a substitute for the CDOM absorption coefficient and fluorescence measured in the laboratory. Similarly, CDOM concentration was highly correlated with DOC concentration (r2 = 0.68, p < 0.001, indicating that in situ CDOM fluorescence sensor measurements could be a proxy for DOC concentration. In addition, significant positive correlations were found between laboratory CDOM absorption coefficients and COD (r2 = 0.83, p < 0.001, TP (r2 = 0.82, p < 0.001 concentrations, suggesting a potential further application for the real-time monitoring of water quality using an in situ CDOM fluorescence sensor.

  5. Predictive modelling of eutrophication in the Pozón de la Dolores lake (Northern Spain) by using an evolutionary support vector machines approach.

    Science.gov (United States)

    García-Nieto, P J; García-Gonzalo, E; Alonso Fernández, J R; Díaz Muñiz, C

    2018-03-01

    Eutrophication is a water enrichment in nutrients (mainly phosphorus) that generally leads to symptomatic changes and deterioration of water quality and all its uses in general, when the production of algae and other aquatic vegetations are increased. In this sense, eutrophication has caused a variety of impacts, such as high levels of Chlorophyll a (Chl-a). Consequently, anticipate its presence is a matter of importance to prevent future risks. The aim of this study was to obtain a predictive model able to perform an early detection of the eutrophication in water bodies such as lakes. This study presents a novel hybrid algorithm, based on support vector machines (SVM) approach in combination with the particle swarm optimization (PSO) technique, for predicting the eutrophication from biological and physical-chemical input parameters determined experimentally through sampling and subsequent analysis in a certificate laboratory. This optimization technique involves hyperparameter setting in the SVM training procedure, which significantly influences the regression accuracy. The results of the present study are twofold. In the first place, the significance of each biological and physical-chemical variables on the eutrophication is presented through the model. Secondly, a model for forecasting eutrophication is obtained with success. Indeed, regression with optimal hyperparameters was performed and coefficients of determination equal to 0.90 for the Total phosphorus estimation and 0.92 for the Chlorophyll concentration were obtained when this hybrid PSO-SVM-based model was applied to the experimental dataset, respectively. The agreement between experimental data and the model confirmed the good performance of the latter.

  6. Chemical composition and trophic state of shallow saline steppe lakes in central Asia (North Kazakhstan).

    Science.gov (United States)

    Boros, Emil; Jurecska, Laura; Tatár, Enikő; Vörös, Lajos; Kolpakova, Marina

    2017-10-09

    The purpose of this study was to identify the prevailing chemical composition and trophic state of the shallow saline steppe lakes of North Kazakhstan along a wide size range (SO 4 and Na-Cl (n = 16; 64%); the Ca, Mg, HCO 3 , and SO 4 ions precipitate with increasing salinity (2-322 g L -1 ); and ion composition shifts from Na>Mg-Cl>SO 4 to Na-Cl. The most of the chemical variables positively, but chlorophyll a negatively, correlated with total dissolved solids, and the total phosphorus had no significant correlation with any variables. The trophic state of these lakes in most cases exceeded the hypertrophic level. The increase in salinity causes change in chemical composition and effects on the phytoplankton development independently from the size of water surface, and the human disturbances had negligible effect on the trophic state of shallow saline lakes in this region of Kazakhstan.

  7. The effects of biomanipulation on the biogeochemistry, carbon isotopic composition and pelagic food web relations of a shallow lake

    Directory of Open Access Journals (Sweden)

    B. M. Bontes

    2006-01-01

    Full Text Available In this study we investigated the effects of experimental biomanipulation on community structure, ecosystem metabolism, carbon biogeochemistry and stable isotope composition of a shallow eutrophic lake in the Netherlands. Three different biomanipulation treatments were applied. In two parts of the lake, isolated from the rest, fish was removed and one part was used as a reference treatment in which no biomanipulation was applied. Stable isotopes have proved useful to trace trophic interactions at higher food web levels but until now methodological limitations have restricted species specific isotope analysis in the plankton community. We applied a new approach based on the combination of fluorescence activated cell sorting (FACS and isotope ratio mass spectrometry (IRMS to trace carbon flow through the planktonic food web. With this method we aimed at obtaining group specific δ13C signatures of phytoplankton and to trace possible shifts in δ13C resulting from fish removal. Biomanipulation led to an increase in transparency and macrophyte biomass and decrease in phytoplankton abundance, but zooplankton numbers did not increase. Fish removal also resulted in high pH, high O2, low CO2 and more negative δ13CDIC values than expected, which is attributed to chemical enhanced diffusion with large negative fractionation. Despite high temporal variation we detected differences between the isotopic signatures of the primary producers and between the different treatments. The fractionation values of green algae (~21 and diatoms (~23 were similar and independent of treatment, while fractionation factors of filamentous cyanobacteria were variable between the treatments that differed in CO2 availability. 13C-labeling of the phytoplankton groups showed that biomanipulation led to increased growth rates of green algae and diatoms at the expense of cyanobacteria. Finally, consumers seemed generalists to the available food sources.

  8. A three-dimensional water quality modeling approach for exploring the eutrophication responses to load reduction scenarios in Lake Yilong (China)

    International Nuclear Information System (INIS)

    Zhao, Lei; Li, Yuzhao; Zou, Rui; He, Bin; Zhu, Xiang; Liu, Yong; Wang, Junsong; Zhu, Yongguan

    2013-01-01

    Lake Yilong in Southwestern China has been under serious eutrophication threat during the past decades; however, the lake water remained clear until sudden sharp increase in Chlorophyll a (Chl a) and turbidity in 2009 without apparent change in external loading levels. To investigate the causes as well as examining the underlying mechanism, a three-dimensional hydrodynamic and water quality model was developed, simulating the flow circulation, pollutant fate and transport, and the interactions between nutrients, phytoplankton and macrophytes. The calibrated and validated model was used to conduct three sets of scenarios for understanding the water quality responses to various load reduction intensities and ecological restoration measures. The results showed that (a) even if the nutrient loads is reduced by as much as 77%, the Chl a concentration decreased only by 50%; and (b) aquatic vegetation has strong interaction with phytoplankton, therefore requiring combined watershed and in-lake management for lake restoration. -- Highlights: ► We quantitatively investigated the non-linear lake responses to load reduction. ► The aquatic ecological condition had a great impact on algal blooms. ► Only water quality improvement cannot ensure the aquatic ecology restoration. -- The lake water quality responds to watershed load reduction in a nonlinear way, which requires combined watershed and in-lake management for lake restoration

  9. Nitrous oxide emissions from Phragmites australis-dominated zones in a shallow lake

    International Nuclear Information System (INIS)

    Yang Zhifeng; Zhao Ying; Xia Xinghui

    2012-01-01

    Nitrous oxide (N 2 O) emissions from Phragmites australis (reed) – dominated zones in Baiyangdian Lake, the largest shallow lake of Northern China, were investigated under different hydrological conditions with mesocosm experiments during the growing season of reeds. The daily and monthly N 2 O emissions were positively correlated with air temperature and the variation of aboveground biomass of reeds (p 2 O emissions from reeds were about 45.8–52.8% of that from the sediments. In terms of the effect of hydrological conditions, N 2 O emissions from the aquatic-terrestrial ecotone were 9.4–26.1% higher than the submerged zone, inferring that the variation of water level would increase N 2 O emissions. The annual N 2 O emission from Baiyangdian Lake was estimated to be about 114.2 t. This study suggested that N 2 O emissions from shallow lakes might be accelerated by the climate change as it has increased air temperature and changed precipitation, causing the variation of water level. - Highlights: ► The daily N 2 O emissions were significant positively correlated with air temperature. ► The monthly N 2 O emissions positively correlated with reed aboveground biomass variations. ► The N 2 O emissions from reeds contributed to 45.8–52.8% of that from the sediment. ► N 2 O emissions from the aquatic-terrestrial ecotone were 9.4–26.1% higher than the submerged zone. ► N 2 O emissions from shallow lakes might be accelerated by the climate change. - The increase of air temperature and water level variation would increase N 2 O emissions, suggesting N 2 O emissions from shallow lakes might be accelerated by climate change.

  10. Distribution and life strategies of two bacterial populations in a eutrophic lake

    Science.gov (United States)

    Weinbauer; Hofle

    1998-10-01

    Monoclonal antibodies and epifluorescence microscopy were used to determine the depth distribution of two indigenous bacterial populations in the stratified Lake Plusssee and characterize their life strategies. Populations of Comamonas acidovorans PX54 showed a depth distribution with maximum abundances in the oxic epilimnion, whereas Aeromonas hydrophila PU7718 showed a depth distribution with maximum abundances in the anoxic thermocline layer (metalimnion), i. e., in the water layer with the highest microbial activity. Resistance of PX54 to protist grazing and high metabolic versatility and growth rate of PU7718 were the most important life strategy traits for explaining the depth distribution of the two bacterial populations. Maximum abundance of PX54 was 16,000 cells per ml, and maximum abundance of PU7718 was 20,000 cells per ml. Determination of bacterial productivity in dilution cultures with different-size fractions of dissolved organic matter (DOM) from lake water indicates that low-molecular-weight (LMW) DOM is less bioreactive than total DOM (TDOM). The abundance and growth rate of PU7718 were highest in the TDOM fractions, whereas those of PX54 were highest in the LMW DOM fraction, demonstrating that PX54 can grow well on the less bioreactive DOM fraction. We estimated that 13 to 24% of the entire bacterial community and 14% of PU7718 were removed by viral lysis, whereas no significant effect of viral lysis on PX54 could be detected. Growth rates of PX54 (0.11 to 0.13 h-1) were higher than those of the entire bacterial community (0.04 to 0.08 h-1) but lower than those of PU7718 (0.26 to 0.31 h-1). In undiluted cultures, the growth rates were significantly lower, pointing to density effects such as resource limitation or antibiosis, and the effects were stronger for PU7718 and the entire bacterial community than for PX54. Life strategy characterizations based on data from literature and this study revealed that the fast-growing and metabolically

  11. Resting cysts of freshwater dinoflagellates in southeastern Georgian Bay (Lake Huron) as proxies of cultural eutrophication

    DEFF Research Database (Denmark)

    McCarthy, Francine M.G.; Mertens, Kenneth Neil; Ellegaard, Marianne

    2011-01-01

    conditions, comprise 60–74% of the cysts identified in Ambrosia (ragweed)-rich sediments in the upper 20 cm of a gravity core taken from Honey Harbour. Euro-Canadian settlement and land-clearing that began in the Midland-Penetanguishene region around A.D. 1840 are evident in the increase in Ambrosia (ragweed...... contained between ~ 750 and 8500 cysts/cm3. However, winnowing by bottom currents and high concentrations of dissolved oxygen adversely impact the dinoflagellate cyst record on the lakebed, and cyst concentrations in easily remobilized muds on bathymetric highs were core changes......-Canadian settlement, when cyst flux was an order of magnitude lower. This is consistent with the restriction of this species to relatively warm, oligotrophic to mesotrophic lakes in North America. An earlier increase in P. willei at the expense of P. wisconsinense in the core from Honey Harbour within pollen zone 3 d...

  12. NO3 uptake in shallow, oligotrophic, mountain lakes: The influence of elevated NO3 concentrations

    Science.gov (United States)

    Nydick, K.R.; LaFrancois, B.M.; Baron, Jill S.

    2004-01-01

    Nutrient enrichment experiments were conducted in 1.2-m deep enclosures in 2 shallow, oligotrophic, mountain lakes. 15N-NO3 isotope tracer was used to compare the importance of phytoplankton and benthic compartments (epilithon, surface sediment [epipelon], and subsurface sediment) for NO3 uptake under high and low NO3 conditions. NO3 uptake approached saturation in the high-N lake, but not in the low-N lake. The capacity of phytoplankton and benthic compartments to take up NO3 differed among treatments and between lakes, and depended on water-column nutrient conditions and the history of NO3 availability. Phytoplankton productivity responded strongly to addition of limiting nutrients, and NO3 uptake was related to phytoplankton biomass and photosynthesis. However, more NO3 usually was taken up by benthic compartments (57–92% combined) than by phytoplankton, even though the response of benthic algal biomass to nutrient additions was less pronounced than that of phytoplankton and benthic NO3 uptake was unrelated to benthic algal biomass. In the low-N lake where NO3 uptake was unsaturated, C content or % was related to NO3 uptake in benthic substrates, suggesting that heterotrophic bacterial processes could be important in benthic NO3 uptake. These results suggest that phytoplankton are most sensitive to nutrient additions, but benthic processes are important for NO3 uptake in shallow, oligotrophic lakes.

  13. Mass development of monospecific submerged macrophyte vegetation after the restoration of shallow lakes: Roles of light, sediment nutrient levels, and propagule density

    NARCIS (Netherlands)

    Verhofstad, M.J.J.M.; Alirangues Núñez, M. M.; Reichman, E. P.; van Donk, E.; Lamers, L. P.M.; Bakker, E. S.

    2017-01-01

    After restoration, eutrophicated shallow freshwaters may show mass development of only one or two submerged macrophyte species, lowering biodiversity and hampering recreation. It is unclear which environmental factors govern this high percentage of the volume inhabited (PVI2) by submerged

  14. Impacts of the 2011 Tsunami on Sediment Characteristics and Macrozoobenthic Assemblages in a Shallow Eutrophic Lagoon, Sendai Bay, Japan.

    Directory of Open Access Journals (Sweden)

    Gen Kanaya

    Full Text Available A huge tsunami is one of the greatest disturbance events in coastal benthic communities, although the ecological consequences are not fully understood. Here we examined the tsunami-induced changes in the sediment environment and macrozoobenthic assemblage in a eutrophic brackish lagoon in eastern Japan. The 7.2-m-high tsunami completely replaced muddy sediment with drifting sea sand throughout the lagoon, leading to the drastic changes in quantity and quality of sedimental organic matters, sulfide contents, and sediment redox condition. Intensive physical stress devastated the benthic community, but the disappearance of sulfidic muddy bottoms significantly improved the habitat quality for macrozoobenthos. The re-established macrozoobenthic community after 5 months was characterized by (1 a 2-fold higher total density, but sharp declines in species richness, diversity, and evenness; (2 an increased density of opportunistic taxa (e.g., polychaete Pseudopolydora spp. and amphipod Monocorophium uenoi in newly created sandy bottoms; and (3 disappearance of several dominant taxa including bivalves and chironomid larvae. These findings indicate that the sensitivity and recovery potential of macrozoobenthos were highly taxa-specific, which was closely related to the taxa's ecological characteristics, including tolerance to physical disturbance, life-history traits, and life form. Our data revealed the rapid recolonization of opportunistic macrozoobenthos after a huge tsunami, which would contribute to the functional recovery of estuarine soft-bottom habitats shortly after a disturbance event.

  15. Emergent Macrophytes Support Zooplankton in a Shallow Tropical Lake: A Basis for Wetland Conservation

    Science.gov (United States)

    Gebrehiwot, Mesfin; Kifle, Demeke; Triest, Ludwig

    2017-12-01

    Understanding the biodiversity value of littoral zones of lakes is a priority for aquatic biodiversity conservation. However, less emphasis has been given to the littoral part of tropical African lakes, with many of the previous researches focusing only on the open water side. The aim of the present study was, therefore, to investigate the impact of the littoral zone of a shallow freshwater tropical lake (Ziway, Ethiopia), dominated by two emergent macrophytes, on zooplankton community structure. We hypothesized that the wetland vegetation serves as a preferred microhabitat for zooplankton communities. A lake with substantial coverage of emergent macrophytes was monitored monthly from January to August, 2016. The monitoring included the measurements of physical, chemical, and biological parameters. Sampling sites were selected to represent areas of the macrophyte vegetation ( Typha latifolia and Phragmites australis) and the open water part of the lake. Sites with macrophyte vegetation were found to be the home of more dense and diverse zooplankton community. However, during the period of high vegetation loss, the density of crustacean zooplankton showed significant reduction within the patches of macrophytes. From biodiversity conservation perspective, it was concluded that the preservation of such small areas of macrophytes covering the littoral zone of lakes could be as important as protecting the whole lake. However, the rapid degradation of wetland vegetation by human activities is a real threat to the lake ecosystem. In the not-too-far future, it could displace and evict riparian vegetation and the biota it supports.

  16. The Ecology of Shallow Lakes - Trophic Interactions in the Pelagial

    DEFF Research Database (Denmark)

    Jeppesen, E.

    publications. The thesis was in June 1998 approved by The Faculty of Natural Sciences at the University of Copenhagen for defence for the doctor´s degree in Natural Sciences (D.sc). This thesis describes how biological interactions in the pelagial of lakes change across both nutrients and depth gradients......The defence took place on December 11, 1998 at The Freshwater Centre, Silkeborg, Denmark. Officiel opponents was Prof. Jürgen Benndorf, University of Technology, Dresden,Germany and Prof. Dag Hessen, University of Oslo, Norway . The defence was led by Lektor Leif Lau Jeppesen, Zoological Institute...

  17. Assessment of the Eutrophication-Related Environmental Parameters in Two Mediterranean Lakes by Integrating Statistical Techniques and Self-Organizing Maps.

    Science.gov (United States)

    Hadjisolomou, Ekaterini; Stefanidis, Konstantinos; Papatheodorou, George; Papastergiadou, Evanthia

    2018-03-19

    During the last decades, Mediterranean freshwater ecosystems, especially lakes, have been under severe pressure due to increasing eutrophication and water quality deterioration. In this article, we compared the effectiveness of different data analysis methods by assessing the contribution of environmental parameters to eutrophication processes. For this purpose, principal components analysis (PCA), cluster analysis, and a self-organizing map (SOM) were applied, using water quality data from two transboundary lakes of North Greece. SOM is considered as an advanced and powerful data analysis tool because of its ability to represent complex and nonlinear relationships among multivariate data sets. The results of PCA and cluster analysis agreed with the SOM results, although the latter provided more information because of the visualization abilities regarding the parameters' relationships. Besides nutrients that were found to be a key factor for controlling chlorophyll-a (Chl - a), water temperature was related positively with algal production, while the Secchi disk depth parameter was found to be highly important and negatively related toeutrophic conditions. In general, the SOM results were more specific and allowed direct associations between the water quality variables. Our work showed that SOMs can be used effectively in limnological studies to produce robust and interpretable results, aiding scientists and managers to cope with environmental problems such as eutrophication.

  18. Assessment of the Eutrophication-Related Environmental Parameters in Two Mediterranean Lakes by Integrating Statistical Techniques and Self-Organizing Maps

    Directory of Open Access Journals (Sweden)

    Ekaterini Hadjisolomou

    2018-03-01

    Full Text Available During the last decades, Mediterranean freshwater ecosystems, especially lakes, have been under severe pressure due to increasing eutrophication and water quality deterioration. In this article, we compared the effectiveness of different data analysis methods by assessing the contribution of environmental parameters to eutrophication processes. For this purpose, principal components analysis (PCA, cluster analysis, and a self-organizing map (SOM were applied, using water quality data from two transboundary lakes of North Greece. SOM is considered as an advanced and powerful data analysis tool because of its ability to represent complex and nonlinear relationships among multivariate data sets. The results of PCA and cluster analysis agreed with the SOM results, although the latter provided more information because of the visualization abilities regarding the parameters’ relationships. Besides nutrients that were found to be a key factor for controlling chlorophyll-a (Chl-a, water temperature was related positively with algal production, while the Secchi disk depth parameter was found to be highly important and negatively related toeutrophic conditions. In general, the SOM results were more specific and allowed direct associations between the water quality variables. Our work showed that SOMs can be used effectively in limnological studies to produce robust and interpretable results, aiding scientists and managers to cope with environmental problems such as eutrophication.

  19. The origin of shallow lakes in the Khorezm Province, Uzbekistan, and the history of pesticide use around these lakes

    Science.gov (United States)

    Rosen, Michael R.; Crootof, Arica; Reidy, Liam; Saito, Laurel; Nishonov, Bakhriddin; Scott, Julian A.

    2018-01-01

    The economy of the Khorezm Province in Uzbekistan relies on the large-scale agricultural production of cotton. To sustain their staple crop, water from the Amu Darya is diverted for irrigation through canal systems constructed during the early to mid-twentieth century when this region was part of the Soviet Union. These diversions severely reduce river flow to the Aral Sea. The Province has >400 small shallow (data indicate that the majority of the lakes investigated are less than 150 years old, which supports a recent origin of the lakes. The thickness of lacustrine sediments in the cores analyzed ranged from 20 to 60 cm in all but two of the lakes, indicating a relatively slow sedimentation rate and a relatively short-term history for the lakes. Hydrologic changes in the lakes are evident from loss on ignition and pollen analyses of a subset of the lake cores. The data indicate that the lakes have transitioned from a dry, saline, arid landscape during pre-lake conditions (low organic carbon content) and low pollen concentrations (in the basal sediments) to the current freshwater lakes (high organic content), with abundant freshwater pollen taxa over the last 50–70 years. Sediments at the base of the cores contain pollen taxa dominated by Chenopodiaceae and Tamarix, indicating that the vegetation growing nearby was tolerant to arid saline conditions. The near surface sediments of the cores are dominated by Typha/Sparganium, which indicate freshwater conditions. Increases in pollen of weeds and crop plants indicate an intensification of agricultural activities since the 1950s in the watersheds of the lakes analyzed. Pesticide profiles of DDT (dichlorodiphenyltrichloroethane) and its degradates and γ-HCH (gamma-hexachlorocyclohexane), which were used during the Soviet era, show peak concentrations in the top 10 cm of some of the cores, where estimated ages of the sediments (1950–1990) are associated with peak pesticide use during the Soviet era. These data

  20. A metabolism-based whole lake eutrophication model to estimate the magnitude and time scales of the effects of restoration in Upper Klamath Lake, south-central Oregon

    Science.gov (United States)

    Wherry, Susan A.; Wood, Tamara M.

    2018-04-27

    A whole lake eutrophication (WLE) model approach for phosphorus and cyanobacterial biomass in Upper Klamath Lake, south-central Oregon, is presented here. The model is a successor to a previous model developed to inform a Total Maximum Daily Load (TMDL) for phosphorus in the lake, but is based on net primary production (NPP), which can be calculated from dissolved oxygen, rather than scaling up a small-scale description of cyanobacterial growth and respiration rates. This phase 3 WLE model is a refinement of the proof-of-concept developed in phase 2, which was the first attempt to use NPP to simulate cyanobacteria in the TMDL model. The calibration of the calculated NPP WLE model was successful, with performance metrics indicating a good fit to calibration data, and the calculated NPP WLE model was able to simulate mid-season bloom decreases, a feature that previous models could not reproduce.In order to use the model to simulate future scenarios based on phosphorus load reduction, a multivariate regression model was created to simulate NPP as a function of the model state variables (phosphorus and chlorophyll a) and measured meteorological and temperature model inputs. The NPP time series was split into a low- and high-frequency component using wavelet analysis, and regression models were fit to the components separately, with moderate success.The regression models for NPP were incorporated in the WLE model, referred to as the “scenario” WLE (SWLE), and the fit statistics for phosphorus during the calibration period were mostly unchanged. The fit statistics for chlorophyll a, however, were degraded. These statistics are still an improvement over prior models, and indicate that the SWLE is appropriate for long-term predictions even though it misses some of the seasonal variations in chlorophyll a.The complete whole lake SWLE model, with multivariate regression to predict NPP, was used to make long-term simulations of the response to 10-, 20-, and 40-percent

  1. Occurrence, spatial distribution, sources, and risks of polychlorinated biphenyls and heavy metals in surface sediments from a large eutrophic Chinese lake (Lake Chaohu).

    Science.gov (United States)

    He, Wei; Bai, Ze-Lin; Liu, Wen-Xiu; Kong, Xiang-Zhen; Yang, Bin; Yang, Chen; Jørgensen, Sven Erik; Xu, Fu-Liu

    2016-06-01

    Surface sediment from large and eutrophic Lake Chaohu was investigated to determine the occurrence, spatial distribution, sources, and risks of polychlorinated biphenyls (PCBs) and heavy metals in one of the five biggest freshwater lakes in China. Total concentration of PCBs (Σ34PCBs) in Lake Chaohu was 672 pg g(-1) dry weight (dw), with a range of 7 to 3999 pg g(-1) dw, which was lower than other water bodies worldwide. The majority of heavy metals were detected at all sampling locations, except for Sr, B, and In. Concentrations of Al, Fe, Ca, Mn, Sr, Co, Zn, Cd, Pb, and Hg were similar to that reported for other lakes globally. Concentrations of K, Mg, Na, Li, Ga, and Ag were greater than the average, whereas those of Cr, Ni, and Cu were lower. Cluster analysis (CA) and positive matrix factorization (PMF) yielded accordant results for the source apportionment of PCBs. The technical PCBs and microbial degradation accounted for 34.2 % and 65.8 % of total PCBs using PMF, and PMF revealed that natural and anthropogenic sources of heavy metals accounted for 38.1 % and 61.8 %, respectively. CA indicated that some toxic heavy metals (e.g., Cd, In, Tl, and Hg) were associated with Ca-Na-Mg minerals rather than Fe-Mn minerals. The uncorrelated results between organic matter revealed by pyrolysis technology and heavy metals might be caused by the existence of competitive adsorption between organic matter and minerals. PCBs and heavy metals were coupling discharge without organochlorine pesticides (OCPs), but with polycyclic aromatic hydrocarbons (PAHs) and polybrominated diphenyl ethers (PBDEs). No sediment sample exceeded the toxic threshold for dioxin-like PCBs (dl-PCBs) set at 20 pg toxicity equivalency quantity (TEQ) g(-1), (max dl-PCBs, 10.9 pg TEQ g(-1)). However, concentrations of Ag, Cd, and Hg were at levels of environmental concern. The sediment in the drinking water source area (DWSA) was threatened by heavy metals from other areas, and some

  2. MODELING WAVE-INDUCED ENTRAINMENT OF MUD IN NEWNANS LAKE, FLORIDA

    Science.gov (United States)

    Many shallow lakes in the southeastern US are eutrophic, and as such, the water quality in these lakes is of concern to state and federal environmental regulatory agencies. Some of these lakes have been classified as impaired with one or more nutrients being the stressor. For the...

  3. Macrophyte Species Drive the Variation of Bacterioplankton Community Composition in a Shallow Freshwater Lake

    Science.gov (United States)

    Zeng, Jin; Bian, Yuanqi; Xing, Peng

    2012-01-01

    Macrophytes play an important role in structuring aquatic ecosystems. In this study, we explored whether macrophyte species are involved in determining the bacterioplankton community composition (BCC) in shallow freshwater lakes. The BCC in field areas dominated by different macrophyte species in Taihu Lake, a large, shallow freshwater lake, was investigated over a 1-year period. Subsequently, microcosm experiments were conducted to determine if single species of different types of macrophytes in an isolated environment would alter the BCC. Denaturing gradient gel electrophoresis (DGGE), followed by cloning and sequence analysis of selected samples, was employed to analyze the BCC. The DGGE results of the field investigations indicated that the BCC changed significantly from season to season and that the presence of different macrophyte species resulted in lower BCC similarities in the summer and fall. LIBSHUFF analysis of selected clone libraries from the summer demonstrated different BCCs in the water column surrounding different macrophytes. Relative to the field observations, the microcosm studies indicated that the BCC differed more pronouncedly when associated with different species of macrophytes, which was also supported by LIBSHUFF analysis of the selected clone libraries. Overall, this study suggested that macrophyte species might be an important factor in determining the composition of bacterial communities in this shallow freshwater lake and that the species-specific influence of macrophytes on BCC is variable with the season and distance. PMID:22038598

  4. Extreme diel dissolved oxygen and carbon cycles in shallow vegetated lakes.

    Science.gov (United States)

    Andersen, Mikkel R; Kragh, Theis; Sand-Jensen, Kaj

    2017-09-13

    A common perception in limnology is that shallow lakes are homogeneously mixed owing to their small water volume. However, this perception is largely gained by downscaling knowledge from large lakes to their smaller counterparts. Here we show that shallow vegetated lakes (less than 0.6 m), in fact, undergo recurring daytime stratification and nocturnal mixing accompanied by extreme chemical variations during summer. Dense submerged vegetation effectively attenuates light and turbulence generating separation between warm surface waters and much colder bottom waters. Photosynthesis in surface waters produces oxygen accumulation and CO 2 depletion, whereas respiration in dark bottom waters causes anoxia and CO 2 accumulation. High daytime pH in surface waters promotes precipitation of CaCO 3 which is re-dissolved in bottom waters. Nocturnal convective mixing re-introduces oxygen into bottom waters for aerobic respiration and regenerated inorganic carbon into surface waters, which supports intense photosynthesis. Our results reconfigure the basic understanding of local environmental gradients in shallow lakes, one of the most abundant freshwater habitats globally. © 2017 The Author(s).

  5. A 150-year record of recent changes in human activity and eutrophication of Lake Wushan from the middle reach of the Yangze River, China

    Directory of Open Access Journals (Sweden)

    Xiangdong YANG

    2010-08-01

    Full Text Available In order to determine baseline conditions (pre-impact and recent changes to lakes on the middle reach of the Yangtze River, China, a lake sediment core was extracted from Lake Wushan covering the last ca 150 years. Detailed chemical, biological (subfossil chironomids, and physical analyses of the lake sediments were undertaken. The data showed consistent trends of increased productivity since the early 1920s, notably significant changes in the chironomid fauna which were associated with changes in the sedimentological and stable isotope proxies. More typically eutrophic chironomid taxa first appeared around this time that had not been present in the lake since at least the 1860s. Further increases in productivity occurred around the 1950s which coincided with the local decline and extirpation of some chironomid taxa, particularly macrophyte associated taxa, which had been present in the lake since at least the late 19th Century. A chironomid-inferred water total phosphorus (CI-TP reconstruction produced accurate levels of water TP compared with contemporary measurements (207.4 μg L-1 TP, and suggested that levels for the late 19th Century were relatively low (50-60 μg L-1 TP. These reconstructions illustrate the baseline levels that existed pre-impact and provide potential targets for restoration, but they also show the magnitude of human impact in this region, which has increased the nutrient content of Lake Wushan fourfold within the last ca 100 years.

  6. Holocene Lake and Shallow Water Sediments at Mograt Island, Sudan

    Directory of Open Access Journals (Sweden)

    Dittrich Annett

    2017-06-01

    Full Text Available This paper presents the results of stratigraphic excavation and soil studies carried out at Mograt Island, the largest of the Nilotic islands in Sudan. Due to its restricted insular environments, Holocene alluvial deposits were observed to be interlocked with archaeological remains of different periods, allowing for a combined chronostratigraphic approach to study both cultural and climatic events. To better understand the environmental context through soil components and pedological features at a microscopic scale, soil block samples were accordingly collected and studied by the application of soil micromorphology. This approach provides insights into the history of Nile terrace aggradation through the suspension of Nile sediment loads under stillwater conditions as well as of the periodical establishment of shallow water pools at the islands′ plateaus by the surface run-off from local rains. Since these patterns vary significantly from the present situation, they offer a key to the scenario in which specific early agricultural and animal herding practices evolved.

  7. What is the influence of a reduction of planktivorous and benthivorous fish on water quality in temperate eutrophic lakes? A systematic review

    DEFF Research Database (Denmark)

    Bernes, Claes; Carpenter, Stephen R.; Gårdmark, Anna

    2015-01-01

    three years afterwards. Piscivore stocking alone has no significant effect. The response of chlorophyll a levels to biomanipulation is stronger in lakes where fish removal is intense, and in lakes which are small and/or have high pre-manipulation concentrations of total phosphorus. Conclusions: Our......Background: In recent decades, many attempts have been made to restore eutrophic lakes through biomanipulation. Reducing the populations of planktivorous and benthivorous fish (either directly or through stocking of piscivorous fish) may induce ecosystem changes that increase water transparency...... using inclusion criteria set out in an a priori protocol. To reduce the risk of bias, we then critically appraised the combined evidence found on each biomanipulation. Data were extracted on outcomes such as Secchi depth and chlorophyll a concentration before, during and/or after manipulation...

  8. Evolution and origin of sympatric shallow-water morphotypes of Lake Trout, Salvelinus namaycush, in Canada's Great Bear Lake.

    Science.gov (United States)

    Harris, L N; Chavarie, L; Bajno, R; Howland, K L; Wiley, S H; Tonn, W M; Taylor, E B

    2015-01-01

    Range expansion in north-temperate fishes subsequent to the retreat of the Wisconsinan glaciers has resulted in the rapid colonization of previously unexploited, heterogeneous habitats and, in many situations, secondary contact among conspecific lineages that were once previously isolated. Such ecological opportunity coupled with reduced competition likely promoted morphological and genetic differentiation within and among post-glacial fish populations. Discrete morphological forms existing in sympatry, for example, have now been described in many species, yet few studies have directly assessed the association between morphological and genetic variation. Morphotypes of Lake Trout, Salvelinus namaycush, are found in several large-lake systems including Great Bear Lake (GBL), Northwest Territories, Canada, where several shallow-water forms are known. Here, we assess microsatellite and mitochondrial DNA variation among four morphotypes of Lake Trout from the five distinct arms of GBL, and also from locations outside of this system to evaluate several hypotheses concerning the evolution of morphological variation in this species. Our data indicate that morphotypes of Lake Trout from GBL are genetically differentiated from one another, yet the morphotypes are still genetically more similar to one another compared with populations from outside of this system. Furthermore, our data suggest that Lake Trout colonized GBL following dispersal from a single glacial refugium (the Mississippian) and support an intra-lake model of divergence. Overall, our study provides insights into the origins of morphological and genetic variation in post-glacial populations of fishes and provides benchmarks important for monitoring Lake Trout biodiversity in a region thought to be disproportionately susceptible to impacts from climate change.

  9. Long-term monitoring reveals carbon-nitrogen metabolism key to microcystin production in eutrophic lakes

    Directory of Open Access Journals (Sweden)

    Lucas J Beversdorf

    2015-05-01

    Full Text Available The environmental drivers contributing to cyanobacterial dominance in aquatic systems have been extensively studied. However, understanding of toxic versus non-toxic cyanobacterial population dynamics and the mechanisms regulating cyanotoxin production remain elusive, both physiologically and ecologically. One reason is the disconnect between laboratory and field-based studies. Here, we combined three years of temporal data, including microcystin (MC concentrations, 16 years of long-term ecological research, and 10 years of molecular data to investigate the potential factors leading to the selection of toxic Microcystis and MC production. Our analysis revealed that nitrogen (N speciation and inorganic carbon (C availability might be important drivers of Microcystis population dynamics and that an imbalance in cellular C: N ratios may trigger MC production. More specifically, precipitous declines in ammonium concentrations lead to a transitional period of N stress, even in the presence of high nitrate concentrations, that we call the toxic phase. Following the toxic phase, temperature and cyanobacterial abundance remained elevated but MC concentrations drastically declined. Increases in ammonium due to lake turnover may have led to down regulation of MC synthesis or a shift in the community from toxic to non-toxic species. While total phosphorus (P to total N ratios were relatively low over the time-series, MC concentrations were highest when total N to total P ratios were also highest. Similarly, high C: N ratios were also strongly correlated to the toxic phase. We propose a metabolic model that corroborates molecular studies and reflects our ecological observations that C and N metabolism may regulate MC production physiologically and ecologically. In particular, we hypothesize that an imbalance between 2-oxoglutarate and ammonium in the cell regulates MC synthesis in the environment.

  10. Effects of simultaneous climate change and geomorphic evolution on thermal characteristics of a shallow Alaskan lake

    Science.gov (United States)

    Griffiths, Jennifer R.; Schindler, Daniel E.; Balistrieri, Laurie S.; Ruggerone, Gregory T.

    2011-01-01

    We used a hydrodynamics model to assess the consequences of climate warming and contemporary geomorphic evolution for thermal conditions in a large, shallow Alaskan lake. We evaluated the effects of both known climate and landscape change, including rapid outlet erosion and migration of the principal inlet stream, over the past 50 yr as well as future scenarios of geomorphic restoration. Compared to effects of air temperature during the past 50 yr, lake thermal properties showed little sensitivity to substantial (~60%) loss of lake volume, as the lake maximum depth declined from 6 m to 4 m driven by outlet erosion. The direction and magnitude of future lake thermal responses will be driven largely by the extent of inlet stream migration when it occurs simultaneously with outlet erosion. Maintaining connectivity with inlet streams had substantial effects on buffering lake thermal responses to warming climate. Failing to account for changing rates and types of geomorphic processes under continuing climate change may misidentify the primary drivers of lake thermal responses and reduce our ability to understand the consequences for aquatic organisms.

  11. Submerged macrophyte biomass distribution in the shallow saline lake Fuente de Piedra (Spain as function of environmental variables

    Directory of Open Access Journals (Sweden)

    Conde-Álvarez, Rafael M.

    2012-06-01

    Full Text Available Aquatic macrophyte biomass, diaspore bank distribution and their relationship to spatial variability of depth, nutrients (nitrite, nitrate, ammonium and soluble reactive phosphorus as well as sediment granulometry in an athalassohaline lake have been studied during one wet hydrological year. The results indicate that species growing in the lake show different spatial distribution patterns throughout the lake. Indirect gradient analysis (canonical analysis results showed a first axis defined as a function of Ulva flexuosa Wulfen biomass which is, in turn, positively correlated with interstitial ammonium and Soluble Reactive Phosphorus (SRP. The second axis was mainly established due to Lamprothamnium papulosum (Wallr. J. Groves biomass which correlated positively to depth and negatively to interstitial ammonium and SRP. These results revealed a NESW eutrophic gradient allowing the U. Flexuosa biomass proliferation. This phenomenon could increase the shadow effect over the rest of the macrophytes inhabiting this shallow lake. Moreover, the eutrophic harmful effect on the macrophyte physiology and over the diaspore bank could have important consequences in the survival of such important populations. The results reported in this study show the need for studies as the base to select sampling points for monitoring this wetland.

    La distribución de la biomasa de los macrófitos acuáticos y de su banco de semillas y oogonios ha sido investigada en relación a la profundidad, los nutrientes (nitrito, nitrato, amonio y fósforo soluble reactivo y la granulometría del sedimento durante un año hidrológico húmedo. Los resultados muestran patrones de distribución diferentes en las distintas especies. Los resultados del análisis canónico basado en análisis de gradiente indirecto muestran un primer eje definido en función de la biomasa de U. Flexuosa, Wulfen que, a su vez, está positivamente correlacionada con el

  12. Aquatic macrophyte richness in Danish lakes in relation to alkalinity, transparency, and lake area

    DEFF Research Database (Denmark)

    Vestergaard, Ole Skafte; Sand-Jensen, Kaj

    2000-01-01

    We examined the relationship between environmental factors and the richness of submerged macrophytes species in 73 Danish lakes, which are mainly small, shallow, and have mesotrophic to hypertrophic conditions. We found that mean species richness per lake was only 4.5 in acid lakes of low...... alkalinity but 12.3 in lakes of high alkalinity due to a greater occurrence of the species-rich group of elodeids. Mean species richness per lake also increased significantly with increasing Secchi depth. No significant relationship between species richness and lake surface area was observed among the entire...... group of lakes or a subset of eutrophic lakes, as the growth of submerged macrophytes in large lakes may be restricted by wave action in shallow water and light restriction in deep water. In contrast, macrophyte species richness increased with lake surface area in transparent lakes, presumably due...

  13. Evaporite deposition in a shallow perennial lake, Qaidam basin, western China

    Energy Technology Data Exchange (ETDEWEB)

    Schubel, K.A.; Lowenstein, T.K. (SUNY, Binghampton, NY (United States)); Spencer, R.J. (Univ. of Calgary, Alberta (Canada)); Pengxi, Z. (Institute of Salt Lakes, Xining (China))

    1991-03-01

    Evaporites accumulate in ephemeral saline-pans, shallow perennial lakes or lagoons, and deep perennial systems. Continuous brine trench exposures of Holocene evaporites from the Qaidam basin provide criteria for the recognition of shallow perennial lake sediments. Based on Landsat photographs, lateral extent of beds (at least 7 km), and sequence thicknesses (maximum 2.5 m), the paleolake is interpreted to have been less than 2.5 m deep and at least 120 km{sup 2} in area. Sediments consist of laminated siliciclastic mud overlain by mud-halite couplets (mm- to cm-scale layers), which represent one vertical shallowing- and concentrating-upwards sequence. The basal laminite marks the onset of deposition in this shallow perennial paleolake. Syndepositional halite textures and fabrics in the overlying mud-halite couplets include cumulates, rafts, and chevrons, draped by mud laminae, and halite layers truncated by horizontal dissolution surfaces (increasing in frequency upwards). Paleolake brines, determined from fluid inclusion melting temperatures, are Na-Mg-Cl-rich and evolve from 0.84 m Mg{sup 2} to 1.52 m Mg{sup 2+} (near the surface). Combinations of the following criteria may be used for the recognition of shallow, nonstratified, perennial lake sediments: lateral continuity of layers; muds undisrupted by subaerial exposure; vertical bottom-growth of halite; halite layers conformably overlain by mud; halite layers truncated by nonuniformly spaced horizontal dissolution surfaces; erosional scours and channels filled with cross-laminated gypsum, halite, and siliciclastic sand and mud; and salinity fluctuations over small stratigraphic intervals within an overall concentrating-upwards sequence.

  14. Multimedia fate modeling of perfluorooctanoic acid (PFOA) and perfluorooctane sulphonate (PFOS) in the shallow lake Chaohu, China

    NARCIS (Netherlands)

    Kong, X.; Liu, W.; He, W.; Xu, F.; Koelmans, Albert A; Mooij, W.M.

    2018-01-01

    Freshwater shallow lake ecosystems provide valuable ecological services to human beings. However, these systems are subject to severe contamination from anthropogenic sources. Per- and polyfluoroalkyl substances (PFASs), including perfluorooctanoic acid (PFOA) and perfluorooctane sulphonate (PFOS),

  15. Extreme Weather Events and Climate Variability Provide a Lens to How Shallow Lakes May Respond to Climate Change

    Directory of Open Access Journals (Sweden)

    Karl Havens

    2016-05-01

    Full Text Available Shallow lakes, particularly those in low-lying areas of the subtropics, are highly vulnerable to changes in climate associated with global warming. Many of these lakes are in tropical cyclone strike zones and they experience high inter-seasonal and inter-annual variation in rainfall and runoff. Both of those factors strongly modulate sediment–water column interactions, which play a critical role in shallow lake nutrient cycling, water column irradiance characteristics and cyanobacterial harmful algal bloom (CyanoHAB dynamics. We illustrate this with three examples, using long-term (15–25 years datasets on water quality and plankton from three shallow lakes: Lakes Okeechobee and George (Florida, USA and Lake Taihu (China. Okeechobee and Taihu have been impacted repeatedly by tropical cyclones that have resulted in large amounts of runoff and sediment resuspension, and resultant increases in dissolved nutrients in the water column. In both cases, when turbidity declined, major blooms of the toxic CyanoHAB Microcystis aeruginosa occurred over large areas of the lakes. In Lake George, periods of high rainfall resulted in high dissolved color, reduced irradiance, and increased water turnover rates which suppress blooms, whereas in dry periods with lower water color and water turnover rates there were dense cyanobacteria blooms. We identify a suite of factors which, from our experience, will determine how a particular shallow lake will respond to a future with global warming, flashier rainfall, prolonged droughts and stronger tropical cyclones.

  16. Changes of the phytoplankton community as symptoms of deterioration of water quality in a shallow lake.

    Science.gov (United States)

    Dembowska, Ewa Anna; Mieszczankin, Tomasz; Napiórkowski, Paweł

    2018-01-25

    Covering more than 60% of the lake surface, macrophytes determined the taxonomic composition of phytoplankton. We have found numerous indications of ecological deterioration and an increased trophic level year to year: an increased total number of taxa; a significantly increased number of species of Chlorophyta, Bacillariophyceae and Cyanoprokaryota; a decreased number of Chrysophyceae; increased Nygaard index, and high diversity and variability of phytoplankton functional groups. Within 2 years (2002 and 2003) algal biomass doubled: from 3.616 to 7.968 mg l -1 . An increased contribution of Chlorococcales and Cyanoprokaryota indicates progressive eutrophication of the lake. The average size of planktonic algae increased, particularly Cyanoprokaryota, where small-celled decreased dramatically and were replaced by large colonies. Cyanoprokaryota remained the dominant group of phytoplankton after 10 years, and the ecosystem of the lake remained in the turbid state. This group of algae had the average biomass 9.734 mg l -1 , which constituted almost 92% of the total biomass.

  17. Sustainable fisheries in shallow lakes: an independent empirical test of the Chinese mitten crab yield model

    Science.gov (United States)

    Wang, Haijun; Liang, Xiaomin; Wang, Hongzhu

    2017-07-01

    Next to excessive nutrient loading, intensive aquaculture is one of the major anthropogenic impacts threatening lake ecosystems. In China, particularly in the shallow lakes of mid-lower Changjiang (Yangtze) River, continuous overstocking of the Chinese mitten crab ( Eriocheir sinensis) could deteriorate water quality and exhaust natural resources. A series of crab yield models and a general optimum-stocking rate model have been established, which seek to benefit both crab culture and the environment. In this research, independent investigations were carried out to evaluate the crab yield models and modify the optimum-stocking model. Low percentage errors (average 47%, median 36%) between observed and calculated crab yields were obtained. Specific values were defined for adult crab body mass (135 g/ind.) and recapture rate (18% and 30% in lakes with submerged macrophyte biomass above and below 1 000 g/m2) to modify the optimum-stocking model. Analysis based on the modified optimum-stocking model indicated that the actual stocking rates in most lakes were much higher than the calculated optimum-stocking rates. This implies that, for most lakes, the current stocking rates should be greatly reduced to maintain healthy lake ecosystems.

  18. Seasonal and inter-annual eutrophication dynamics in a hypereutrophic shallow coastal lagoon from ten years of satellite observations and in-situ data

    Science.gov (United States)

    Pitarch, Jaime; Ruiz-Verdú, Antonio; Soria, Juan M.; Santoleri, Rosalia

    2016-04-01

    The Albufera de Valencia (39.33 N, 0.37 W) is a hypereutrophic shallow coastal lagoon, having a near round shape of ~ 5 km diameter and ~ 1 m average depth. At the west side, the lake is separated from the sea by a narrow land strip, but three artificial channels allow connection to the sea, regulated by gates. The rest of the lake is surrounded by rice fields that were made by gaining surface from the lake around a century ago. Nowadays, the ecological state of the lake is very degraded. Freshwater inflow is insufficient and residence time is too high. Despite some improvements in waste water treatment, high loads of sediment-stored nutrients are often resuspended due to habitual strong winds and made available for primary production. The previously abundant bottom vegetation disappeared decades ago and secchi depth does not reach more than few tens of centimeters. The lake suffers from cyanobacterial blooms and massive fish deaths. Despite its vital importance as a coastal wetland in the western Mediterranean region, its water quality is not routinely monitored, so its seasonality and eventual blooming events have not been sistematically studied. In this study, we aim at filling this gap using satellite data. Medium-resolution satellite-borne sensors constitute an appropriate tool for this sake due to the lake's medium size and little cloud cover time over the region. In particular, the European MERIS sensor (2002-2012) is specially well suited due to its unique spectral bands configuration for cyanobacterial detection. Apart from the utility of the results themselves, study of this sensor provides a strong baseline for operational utilization of its successor, the new-coming European Sentinel 3-OLCI sensor. We have processed the full archived MERIS archived data. By adequate choice of band ratios and posterior calibration to in-situ samples, the time series of chlorophyll concentration is derived. Derived seasonality reveals a pattern that is determined by the

  19. Continental-scale patterns of nutrient and fish effects on shallow lakes: synthesis of a pan-European mesocosm experiment

    NARCIS (Netherlands)

    Moss, B.; Stephen, D.; Balayla, D.; Bécares, E.; Collings, S.E.; Fernández-Aláez, C.; Fernández-Aláez, M.; Ferriol, C.; García, P.; Gomá, J.; Gyllström, M.; Hansson, L-A.; Hietala, J.; Kairesalo, T.; Rosa Miracle, M.; Romo, S.; Rueda, J.; Russell, V.; Ståhl-Delbanco, A.; Svensson, M.; Vakkilainen, K.; Valentín, M.; van de Bund, W.; Van Donk, E.; Vicente, E.; Villena, M.J.

    2004-01-01

    1. Results are analysed from 11 experiments in which effects of fish addition and nutrient loading on shallow lakes were studied in mesocosms. The experiments, five in 1998, six in 1999, were carried out in six lakes, distributed from Finland to southern Spain, according to a standard protocol. 2.

  20. Structure and spatial patterns of macrobenthic community in Tai Lake, a large shallow lake, China

    Science.gov (United States)

    Di Li,; Erickson, Richard A.; Song Tang,; Xuwen Li,; Niu, Zhichun; Xia Wang,; Hongling Liu,; Hongxia Yu,

    2016-01-01

    Tai Lake (Chinese: Taihu), the third-largest freshwater lake in China, suffers from harmful cyanobacteria blooms that are caused by economic development and population growth near the lake. Several studies have focused on phytoplankton in Tai Lake after a drinking water crisis in 2007; however, these studies primarily focused on microcystin bioaccumulation and toxicity to individual species without examining the effects of microcystin on macrobenthic community diversity. In this study, we conducted a survey of the lake to examine the effects of microcystine and other pollutants on marcobenthic community diversity. A totally of forty-nine species of macroinvertebrates were found in Tai Lake. Limnodrilus hoffmeisteri and Corbicula fluminea were the most abundant species. Cluster-analysis and one-way analysis of similarity (ANOSIM) identified three significantly different macrobenthic communities among the sample sites. More specifically, sites in the eastern bays, where aquatic macrophytes were abundant, had the highest diversity of macrobenthic communities, which were dominated by Bellamya aeruginosa, Bellamya purificata, L. hoffmeisteri, and Alocinma longicornis. Sites in Zhushan Bay contained relatively diverse communities, mainly composed of L. hoffmeisteri, C. fluminea, L. claparederanus, R. sinicus, and Cythura sp. Sites in the western region, Meiliang Bay and Wuli Bay had the lowest diversity, mainly composed ofL. hoffmeisteri, C. fluminea, Branchiura sowerbyi, and Rhyacodrilus sinicus. In addition, the relationships between macrobenthic metrics (Shannon–Wiener, Margalef, and Pielou) and environmental variables showed that community structure and spatial patterns of macrobenthos in Tai Lake were significantly influenced by chemical oxygen demand (CODCr), biochemical oxygen demand (BOD5), lead (Pb), and microcystin-LR (L for leucine and R for arginine). Our findings provide critical information that could help managers and policymakers

  1. Remote sensing of macrophyte morphological traits: Implications for the management of shallow lakes

    Directory of Open Access Journals (Sweden)

    Paolo Villa

    2017-03-01

    Full Text Available Macrophytes are important elements of freshwater ecosystems, fulfilling a pivotal role in biogeochemical cycles. The synoptic capabilities provided by remote sensing make it a powerful tool for monitoring aquatic vegetation characteristics and the functional status of shallow lake systems in which they occur. The latest generation of airborne and spaceborne imaging sensors can be effectively exploited for mapping morphologically – and physiologically – relevant vegetation features based on their canopy spectral response. The objectives of this study were to calibrate semi-empirical models for mapping macrophyte morphological traits (i.e., fractional cover, leaf area index and above-water biomass from hyperspectral data, and to investigate the capabilities of remote sensing in supporting macrophyte monitoring and management. We calibrated spectral models using in situ reflectance and morphological trait measures and applied them to airborne hyperspectral imaging data, acquired over two shallow European water bodies (Lake Hídvégi, in Hungary, and Mantua lakes system, in Italy in two key phenological phases. Maps of morphological traits were produced covering a broad range of aquatic plant types (submerged, floating, and emergent, common to temperate and continental regions, with an error level of 5.4% for fractional cover, 0.10 m2 m-2 for leaf area index, and 0.06 kg m-2 for above-water biomass. Based on these maps, we discuss how remote sensing could support monitoring strategies and shallow lake management with reference to our two case studies: i.e., by providing insight into spatial and species-wise variability, by assessing nutrient uptake by aquatic plants, and by identifying hotspot areas where invasive species could become a threat to ecosystem functioning and service provision.

  2. Evaluation of Water Quality in Shallow Lakes, Case Study of Lake Uluabat

    Directory of Open Access Journals (Sweden)

    Saadet İLERİ

    2014-04-01

    Full Text Available Lake Uluabat, located 20 km south of the Marmara Sea, between 42° 12' North latitude, 28° 40'East longitude and is located in the province of Bursa. The Lake is one of the richest lakes in terms of aquatic plants besides fish and bird populations in Turkey. In this study, water quality of the Lake was monitored from June 2008 to May 2009 during the 12 month period with the samples taken from 8 points in the lake and spatial and temporal variations of the parameters were examined. pH, temperature (T, electrical conductivity (EC, dissolved oxygen (DO, suspended solids (SS, secchi depth (SD, water level (WL, nitrate nitrogen (NO3-N, total nitrogen (TN, phosphate-phosphorus (PO4-P, total phosphorus (TP, alkalinity, chemical oxygen demand (COD and chlorophyll-a (Chl-a were the monitoring parameters. As a result, concentrations of the parameters were found at high levels especially the 1st, 4th, 5th, and 8th stations and temporally were found at high levels often in the summer. According to the results of analysis of variance, regional and temporal variations of all parameters were found important except SS and NO3-N

  3. Concentrations and potential health hazards of organochlorine pesticides in (shallow) groundwater of Taihu Lake region, China.

    Science.gov (United States)

    Wu, Chunfa; Luo, Yongming; Gui, Tong; Huang, Yujuan

    2014-02-01

    A total of 27 shallow groundwater samples were collected from the Taihu Lake region (TLR), to determine the concentrations of 14 organochlorine pesticide (OCP) species, identify their possible sources, and estimate health risk of drinking the shallow groundwater. All OCP species occurred in the shallow groundwater of TLR with high detection frequency except p, p'-dichlorodiphenyldichlorothane (p, p'-DDD) and p, p'-dichlorodiphenyltrichloroethane (p, p'-DDT). DDTs and hexachlorocyclohexanes (HCHs) were the dominant OCP contaminants in the shallow groundwater of TLR, and they account for 44.2% total OCPs. The low α-HCH/γ-HCH ratio, high β-HCH/(α+γ)-HCH ratio and β-HCH being the dominant HCH isomers for the majority of samples suggest that the HCHs were mainly from the historical use of lindane after a period of degradation. p, p'-DDE being the dominant DDT metabolite for all the samples indicated that the DDTs were mainly from the historical residues. Compositional analysis also suggested that there were fresh input sources of heptachlors, aldrins and endrins in addition to the historical residues. Correlation analysis indicated the hexachlorobenzene (HCB) impurity in the shallow groundwater of TLR was likely from the historical application of lindane and technical HCH (a mixture of HCH isomers that is produced by photochlorination of benzene). Carcinogenic risk values for α-HCH, heptachlor, heptachlor epoxide, aldrins and dieldrin in the shallow groundwater in majority area of TLR were found to be >10(-6), posing a potentially serious cancer risk to those dependant on shallow groundwater for drinking water. © 2013.

  4. Factors affecting assemblage attributes of freshwater Oligochaeta in Neotropical shallow floodplain lakes

    Directory of Open Access Journals (Sweden)

    Vanessa Ernandes de Amo

    2017-12-01

    Full Text Available Abstract Aim: Identify the effects of sediment composition and water conditions on diversity, richness, evenness, density and composition of freshwater Oligochaeta in shallow floodplain lakes. Methods We sampled 13 shallow floodplain lakes quarterly during the year 2010 in the Upper Paraná River floodplain. In each lake, four sediment samples were taken from the shore and central regions, three of them were used for biological analysis, and one for granulometric analysis. Concomitantly, temperature, dissolved oxygen, pH, conductivity, alkalinity, turbidity and chlorophyll-a were also measured. Initially, the biological samples were analyzed by a stereoscopic microscope. Oligochaeta individuals were identified under optical microscope at the lowest possible taxonomic level. For data analysis, we quantified density, richness, evenness and diversity index of freshwater Oligochaeta. In order to show differences between the months and the analyzed lakes, in relation to the percentages of coarse and fine organic material, the nonparametric Kruskal Wallis test was used. We also calculated the sediment granulometric diversity using the Shannon-Wienner index, using a simple regression analysis. We correlated assemblage attributes of Oligochaeta with sediment diversity and the assemblage species with the limnological variables using the Spearman correlation. Results A total of 2,090 individuals were found distributed among 27 species. From the total individuals number, 57% were Pristina americana, followed by Dero (Dero righii with 13%. Assemblage attributes were not significantly correlated with sediment diversity, and 7 of the 27 species recorded showed significant correlations with at least some of the abiotic variables. Conclusions We verified that the abiotic variables of the water present greater influence on the attributes of the assemblage of freshwater Oligochaeta, when compared with sediment influences. Although we found low local diversity of

  5. Submerged macrophytes modify bacterial community composition in sediments in a large, shallow, freshwater lake.

    Science.gov (United States)

    Zhao, Da-Yong; Liu, Peng; Fang, Chao; Sun, Yi-Meng; Zeng, Jin; Wang, Jian-Qun; Ma, Ting; Xiao, Yi-Hong; Wu, Qinglong L

    2013-04-01

    Submerged aquatic macrophytes are an important part of the lacustrine ecosystem. In this study, the bacterial community compositions in the rhizosphere sediments from three kinds of submerged macrophytes (Ceratophyllum demersum, Potamogeton crispus, and Vallisneria natans) were investigated to determine whether submerged macrophytes could drive the variation of bacterial community in the eutrophic Taihu Lake, China. Molecular techniques, including terminal restriction fragment length polymorphism (T-RFLP) of PCR-amplified 16S rRNA gene and clone libraries, were employed to analyze the bacterial community compositions. Remarkable differences of the T-RFLP patterns were observed among the different samples, and the results of LIBSHUFF analysis also confirmed that the bacterial community compositions in the rhizosphere sediments of three kinds of submerged macrophytes were statistically different from that of the unvegetated sediment. Acidobacteria, Deltaproteobacteria, and Betaproteobacteria were the dominant bacterial groups in the rhizosphere sediments of Ceratophyllum demersum, Potamogeton crispus, and Vallisneria natans, respectively, accounting for 15.38%, 29.03%, and 18.00% of the total bacterial abundances. Our study demonstrated that submerged macrophytes could influence the bacterial community compositions in their rhizosphere sediments, suggesting that macrophytes have an effect on the cycling and transportation of nutrients in the freshwater lake ecosystem.

  6. The role of wind field induced flow velocities in destratification and hypoxia reduction at Meiling Bay of large shallow Lake Taihu, China.

    Science.gov (United States)

    Jalil, Abdul; Li, Yiping; Du, Wei; Wang, Wencai; Wang, Jianwei; Gao, Xiaomeng; Khan, Hafiz Osama Sarwar; Pan, Baozhu; Acharya, Kumud

    2018-01-01

    Wind induced flow velocity patterns and associated thermal destratification can drive to hypoxia reduction in large shallow lakes. The effects of wind induced hydrodynamic changes on destratification and hypoxia reduction were investigated at the Meiling bay (N 31° 22' 56.4″, E 120° 9' 38.3″) of Lake Taihu, China. Vertical flow velocity profile analysis showed surface flow velocities consistency with the wind field and lower flow velocity profiles were also consistent (but with delay response time) when the wind speed was higher than 6.2 m/s. Wind field and temperature found the control parameters for hypoxia reduction and for water quality conditions at the surface and bottom profiles of lake. The critical temperature for hypoxia reduction at the surface and the bottom profile was ≤24.1C° (below which hypoxic conditions were found reduced). Strong prevailing wind field (onshore wind directions ESE, SE, SSE and E, wind speed ranges of 2.4-9.1 m/s) reduced the temperature (22C° to 24.1C°) caused reduction of hypoxia at the near surface with a rise in water levels whereas, low to medium prevailing wind field did not supported destratification which increased temperature resulting in increased hypoxia. Non-prevailing wind directions (offshore) were not found supportive for the reduction of hypoxia in study area due to less variable wind field. Daytime wind field found more variable (as compared to night time) which increased the thermal destratification during daytime and found supportive for destratification and hypoxia reduction. The second order exponential correlation found between surface temperature and Chlorophyll-a (R 2 : 0.2858, Adjusted R-square: 0.2144 RMSE: 4.395), Dissolved Oxygen (R 2 : 0.596, Adjusted R-square: 0.5942, RMSE: 0.3042) concentrations. The findings of the present study reveal the driving mechanism of wind induced thermal destratification and hypoxic conditions, which may further help to evaluate the wind role in eutrophication

  7. Paleolimnological records of nitrogen deposition in shallow, high-elevation lakes of Grand Teton National Park, Wyoming, USA

    Science.gov (United States)

    Spaulding, Sarah A.; Otu, Megan K.; Wolfe, Alexander P.; Baron, Jill S.

    2015-01-01

    Reactive nitrogen (Nr) from anthropogenic sources has been altering ecosystem function in lakes of the Rocky Mountains, other regions of western North America, and the Arctic over recent decades. The response of biota in shallow lakes to atmospheric deposition of Nr, however, has not been considered. Benthic algae are dominant in shallow, high-elevation lakes and are less sensitive to nutrient inputs than planktonic algae. Because the benthos is typically more nutrient rich than the water column, shallow lakes are not expected to show evidence of anthropogenic Nr. In this study, we assessed sedimentary evidence for regional Nr deposition, sediment chronology, and the nature of algal community response in five shallow, high-elevation lakes in Grand Teton National Park (GRTE). Over 140 diatom taxa were identified from the sediments, with a relatively high species richness of taxa characteristic of oligotrophic conditions. The diatom assemblages were dominated by benthic taxa, especially motile taxa. The GRTE lakes demonstrate assemblage-wide shifts in diatoms, including 1) synchronous and significant assemblage changes centered on ~1960 AD; 2) pre-1960 assemblages differed significantly from post-1960 assemblages; 3) pre-1960 diatom assemblages fluctuated randomly, whereas post- 1960 assemblages showed directional change; 4) changes in δ15N signatures were correlated with diatom community composition. These results demonstrate recent changes in shallow high18 elevation lakes that are most correlated with anthropogenic Nr. It is also possible, however, that the combined effect of Nr deposition and warming is accelerating species shifts in benthic diatoms. While uncertainties remain about the potential synergy of Nr deposition and warming, this study adds shallow lakes to the growing list of impacted high-elevation localities in western North America.

  8. Spatial and temporal variability of greenhouse gas emissions from a small and shallow temperate lake

    Science.gov (United States)

    Praetzel, Leandra; Schmiedeskamp, Marcel; Broder, Tanja; Hüttemann, Caroline; Jansen, Laura; Metzelder, Ulrike; Wallis, Ronya; Knorr, Klaus-Holger; Blodau, Christian

    2017-04-01

    Small inland waters (spots" and "hot moments" that could contribute significantly to total emissions. To address this knowledge gap, we determined CO2 and CH4 emissions and dynamics to identify their controlling environmental factors in a polymictic small (1.4 ha) and shallow (max. depth approx. 1.5 m) crater lake ("Windsborn") in the Eifel uplands in south-west Germany. As Lake Windsborn has a small catchment area (8 ha) and no surficial inflows, it serves well as a model system for the identification of factors and processes controlling emissions. In 2015, 2016 and 2017 we measured CO2 and CH4 gas fluxes with different techniques across the sediment/water and water/atmosphere interface. Atmospheric exchange was measured using mini-chambers equipped with CO2 sensors and with an infra-red greenhouse gas analyzer for high temporal resolution flux measurements. Ebullition of CH4 was quantified with funnel traps. Sediment properties were examined using pore-water peepers. All measurements were carried out along a transect covering both littoral and central parts of the lake. Moreover, a weather station on a floating platform in the center of the lake recorded meteorological data as well as CO2 concentration in different depths of the water column. So far, Lake Windsborn seems to be a source for both CO2 and CH4 on an annual scale. CO2 emissions generally increased from spring to summer. Even though CO2 uptake could be observed during some periods in spring and fall, CO2 emissions in the summer exceeded the uptake. CO2 and CH4 emissions also appeared to be spatially variable between littoral areas and the inner lake. Shallow areas turned out to be "hot spots" of CO2 emissions whereas CH4 emissions were - against our expectations - highest in the center of the lake. Moreover, CH4 ebullition contributed substantially to total CH4 emissions. Our results show the importance of spatially and temporally highly resolved long-term measurements of greenhouse gas emissions and

  9. Focused groundwater discharge of phosphorus to a eutrophic seepage lake (Lake Væng, Denmark): implications for lake ecological state and restoration

    DEFF Research Database (Denmark)

    Kidmose, Jacob; Nilsson, Bertel; Engesgaard, Peter

    2013-01-01

    and borehole data. Discharge was found to be much focused and opposite to expected increase away from the shoreline. The average total phosphorus concentration in discharging groundwater sampled just beneath the lakebed was 0.162 mg TP/l and thereby well over freshwater ecological thresholds (0...... paths through the aquifer–lakebed interface either being overland flow through a seepage face, or focused in zones with very high discharge rates. In-lake springs have measured discharge of up to 7.45 m3 per m2 of lakebed per day. These findings were based on seepage meter measurements at 18 locations...

  10. Comment on: "Bachmann, R. W., M. V. Hoyer, and D. E. Canfield. 2013. The extent that natural lakes in the United States of America have been changed by cultural eutrophication. Limnology and Oceanography 58:945-950."

    Science.gov (United States)

    In a recent paper, Bachmann et al. (2013) conclude, based on paleolimnological reconstructions, that lakes in the conterminous U.S. have undergone very little cultural eutrophication. They go on to suggest that their results invalidate the efforts of the U.S. EPA to establish num...

  11. Using Snow Fences to Augument Fresh Water Supplies in Shallow Arctic Lakes

    Energy Technology Data Exchange (ETDEWEB)

    Stuefer, Svetlana

    2013-03-31

    This project was funded by the U.S. Department of Energy, National Energy Technology Laboratory (NETL) to address environmental research questions specifically related to Alaska's oil and gas natural resources development. The focus of this project was on the environmental issues associated with allocation of water resources for construction of ice roads and ice pads. Earlier NETL projects showed that oil and gas exploration activities in the U.S. Arctic require large amounts of water for ice road and ice pad construction. Traditionally, lakes have been the source of freshwater for this purpose. The distinctive hydrological regime of northern lakes, caused by the presence of ice cover and permafrost, exerts influence on lake water availability in winter. Lakes are covered with ice from October to June, and there is often no water recharge of lakes until snowmelt in early June. After snowmelt, water volumes in the lakes decrease throughout the summer, when water loss due to evaporation is considerably greater than water gained from rainfall. This balance switches in August, when air temperature drops, evaporation decreases, and rain (or snow) is more likely to occur. Some of the summer surface storage deficit in the active layer and surface water bodies (lakes, ponds, wetlands) is recharged during this time. However, if the surface storage deficit is not replenished (for example, precipitation in the fall is low and near‐surface soils are dry), lake recharge is directly affected, and water availability for the following winter is reduced. In this study, we used snow fences to augment fresh water supplies in shallow arctic lakes despite unfavorable natural conditions. We implemented snow‐control practices to enhance snowdrift accumulation (greater snow water equivalent), which led to increased meltwater production and an extended melting season that resulted in lake recharge despite low precipitation during the years of the experiment. For three years (2009

  12. Potential direct and indirect effects of climate change on a shallow natural lake fish assemblage

    Science.gov (United States)

    Breeggemann, Jason J.; Kaemingk, Mark A.; DeBates, T.J.; Paukert, Craig P.; Krause, J.; Letvin, Alexander P.; Stevens, Tanner M.; Willis, David W.; Chipps, Steven R.

    2015-01-01

    Much uncertainty exists around how fish communities in shallow lakes will respond to climate change. In this study, we modelled the effects of increased water temperatures on consumption and growth rates of two piscivores (northern pike [Esox lucius] and largemouth bass [Micropterus salmoides]) and examined relative effects of consumption by these predators on two prey species (bluegill [Lepomis macrochirus] and yellow perch [Perca flavescens]). Bioenergetics models were used to simulate the effects of climate change on growth and food consumption using predicted 2040 and 2060 temperatures in a shallow Nebraska Sandhill lake, USA. The patterns and magnitude of daily and cumulative consumption during the growing season (April–October) were generally similar between the two predators. However, growth of northern pike was always reduced (−3 to −45% change) compared to largemouth bass that experienced subtle changes (4 to −6% change) in weight by the end of the growing season. Assuming similar population size structure and numbers of predators in 2040–2060, future consumption of bluegill and yellow perch by northern pike and largemouth bass will likely increase (range: 3–24%), necessitating greater prey biomass to meet future energy demands. The timing of increased predator consumption will likely shift towards spring and fall (compared to summer), when prey species may not be available in the quantities required. Our findings suggest that increased water temperatures may affect species at the edge of their native range (i.e. northern pike) and a potential mismatch between predator and prey could exist.

  13. Replicated mesocosm study on the role of natural ultraviolet radiation in high CDOM, shallow lakes.

    Science.gov (United States)

    Pérez, A Patricia; Diaz, Mónica M; Ferraro, Marcela A; Cusminsky, Gabriela C; Zagarese, Horacio E

    2003-02-01

    The role of ultraviolet radiation on shallow, high CDOM (colored dissolved organic matter) lakes was investigated during two consecutive summers (1999 and 2000) in replicated mesocosms (rectangular fiberglass tanks). Each tank (volume: 300 L; depth: 40 cm) was covered with a layer (approximately 3 cm) of sediment from lake El Toro (40 degrees 14' S; 70 degrees 22' W) and filled with filtered water. The experimental design consisted of two treatments: full natural radiation (UV-exposed) and natural radiation without ultraviolet radiation (UV-shielded). UV-exposed and UV-shielded treatments differed in most studied variables as revealed by repeated measures ANOVA. UV-exposed tanks displayed lower CDOM levels (dissolved absorbance) of lower average molecular size (absorbance ratio between 250 and 365 nm), higher bacterial biomass, and lower chlorophyll a concentration. The effect on consumers (rotifers and crustaceans) was less noticeable. The results are consistent with UV stimulation of bacteria production mediated by higher rates of CDOM photobleaching, and the photoinhibition of planktonic algae. Thus, a major effect of UVR in shallow, high CDOM ecosystems appears to be the stimulation of heterotrophic pathways and a simultaneous inhibition of photoautotrophs.

  14. Size-dependent responses of zooplankton to submerged macrophyte restoration in a subtropical shallow lake

    Science.gov (United States)

    Zeng, Lei; He, Feng; Zhang, Yi; Liu, Biyun; Dai, Zhigang; Zhou, Qiaohong; Wu, Zhenbin

    2018-03-01

    To explore the size-dependent responses of zooplankton to submerged macrophyte restoration, we collected macrophyte, zooplankton and water quality samples seasonally from a subtropical shallow lake from 2010 to 2012. Special attention was given to changes in rotifers and crustaceans (cladocerans and copepods). The rotifers were grouped into three size classes (400 μm) to explore their size-related responses to macrophyte restoration. The results showed that during the restoration, the annual mean biomass and macrophyte coverage increased significantly from 0 to 637 g/m2 and 0 to 27%, respectively. In response, the density and biomass of crustaceans and the crustacean-to-rotifer ratio increased significantly, while the rotifer density decreased significantly. Moreover, rotifers showed significant sizedependent responses to macrophyte restoration. Specially, rotifers sized zooplankton tended to boom, while that of small rotifers was inhibited during macrophyte restoration. Redundancy analysis (RDA) revealed positive correlations between macrophytes and crustaceans, rotifers and COD or Chl- a, but negative correlations between macrophytes and COD or Chl- a, and between crustaceans and Chl- a. Moreover, the results indicate that increased predation on phytoplankton by large-sized zooplankton might be an important mechanism for macrophyte restoration during development of aquatic ecosystems, and that this mechanism played a very important role in promoting the formation of a clear-water state in subtropical shallow lakes.

  15. Long-term changes in the flora and vegetation of Lake Mikołajskie (Poland as a result of its eutrophication

    Directory of Open Access Journals (Sweden)

    Barbara Solińska-Górnicka

    2014-01-01

    Full Text Available Changes in littoral flora as well as aquatic and swamp vegetation were analysed with increasing eutrophication of the mesotrophic Lake Mikołajskie. Over 30 years the habitat conditions of the lake deteriorated and the phy-tolittoral was reduced from a zone 6 metres wide to one of only 2 metres. In addition, the number of submerged macrophyte species decreased by 50% and the frequency of most of the remaining species declined severalfold. No new species were encountered. Species retreating from the lake littoral included all Chara species, Potamogeton obtusifolius, P. natans and Hydrocharis morsus-ranae. A significant lowering of the phytosociological diversity and species richness of aquatic and swamp communities was observed. By 1994, six of the 12 associations identified in 1964 and representing the submerged and floating-leaved vegetation (e.g. Nitellopsidetum ubtusae, Charetum asperae and Potamogetonetum compressi were no longer present. In turn, 6 swamp communities from among the original 14 identified in the lake were lacking (e.g. Typhetum angustifoliae, Sugittario-Sparganietum emersi and Eleocharitetum palustris. At the same time, two new aquatic and swamp communities appeared (Ranunculetum circinuti, Myriophylletum spicati, Caricetum acutiformis and Caricetum distichae. In contrast there was an increase in the species richness of reedswamp communities due to an influx of marshland species. While the 1990s witnessed a distinct decrease in concentrations of nutrients in Lake Mikołajskie, the consequent increase in water transparency was not associated with an increase in the area of submerged macrophytes, or the species richness of aquatic vegetation.

  16. Environmental influence on cyanobacteria abundance and microcystin toxin production in a shallow temperate lake.

    Science.gov (United States)

    Lee, Tammy A; Rollwagen-Bollens, Gretchen; Bollens, Stephen M; Faber-Hammond, Joshua J

    2015-04-01

    The increasing frequency of harmful cyanobacterial blooms in freshwater systems is a commonly recognized problem due to detrimental effects on water quality. Vancouver Lake, a shallow, tidally influenced lake in the flood plain of the Columbia River within the city of Vancouver, WA, USA, has experienced numerous summertime cyanobacterial blooms, dominated by Aphanizomenon sp. and Anabaena sp. Cyanobacteria abundance and toxin (microcystin) levels have been monitored in this popular urban lake for several years; however, no previous studies have identified which cyanobacteria species produce toxins, nor analyzed how changes in environmental variables contribute to the fluctuations in toxic cyanobacteria populations. We used a suite of molecular techniques to analyze water samples from Vancouver Lake over two summer bloom cycles (2009 and 2010). Both intracellular and extracellular microcystin concentrations were measured using an ELISA kit. Intracellular microcystin concentrations exceeded WHO guidelines for recreational waters several times throughout the sampling period. PCR results demonstrated that Microcystis sp. was the sole microcystin-producing cyanobacteria species present in Vancouver Lake, although Microcystis sp. was rarely detected in microscopical counts. qPCR results indicated that the majority of the Microcystis sp. population contained the toxin-producing gene (mcyE), although Microcystis sp. abundance rarely exceeded 1 percent of overall cyanobacteria abundance. Non-metric multidimensional scaling (NMDS) revealed that PO4-P was the main environmental variable influencing the abundance of toxic and non-toxic cyanobacteria, as well as intracellular microcystin concentrations. Our study underscores the importance of using molecular genetic techniques, in addition to traditional microscopy, to assess the importance of less conspicuous species in the dynamics of harmful algal blooms. Copyright © 2014 Elsevier Inc. All rights reserved.

  17. Effects of short-term sediment nutrient enrichment and grazer (Neritina reclivata removal on sediment microalgae in a shallow eutrophic estuary (Alabama, USA

    Directory of Open Access Journals (Sweden)

    Just Cebrian

    2012-12-01

    Full Text Available The olive snail (Neritina reclivata is ubiquitous in tropical and sub-tropical systems of the Gulf of Mexico, however its impacts on sediment microalgae have been little studied. Many coastal systems around the world are being eutrophied due to human activities, and seemingly they will continue to be eutrophied to a further extent in the future. Exploring the single and combined impacts of further nutrient enrichment and grazing by the olive snail on sediment microalgae in such eutrophic systems is an important question for our understanding and management of these systems. Here we examine the effects of short-term nutrient enrichment and grazing by the olive snail N. reclivata on sediment microalgal biomass and composition in a shallow eutrophic estuary (Weeks Bay, Alabama, USA of the Northern Gulf of Mexico. For this, we performed a series of factorial experiments adding or not nutrients and removing or not the snail, for a total of four treatments in each experiment: ambient grazing, ambient nutrients; ambient grazing, increased nutrients; no grazing, ambient nutrients; and no grazing, increased nutrients. We did not find any significant impact of nutrient addition in any of the eight short-term (i.e. four days experiments carried out. Impacts by the snail were minor; we only found a decrease in biomass due to snail grazing in one of the eight experiments, and no impacts on microalgal (i.e. diatom composition. High ambient nutrient concentrations in the sediment porewater and low snail abundances on the sediment could explain these findings. Our results suggest that ephemeral, short-term nutrient pulses into eutrophic coastal systems of the Northern Gulf of Mexico, such as Weeks Bay (Alabama, USA, should not greatly affect the abundance of sediment microalgae, even though those pulses occur in well-lit areas. The results further suggest the snail N. reclivata is not a major control of sediment microalgal populations in the subtidal

  18. Intense methane ebullition from open water area of a shallow peatland lake on the eastern Tibetan Plateau.

    Science.gov (United States)

    Zhu, Dan; Wu, Yan; Chen, Huai; He, Yixin; Wu, Ning

    2016-01-15

    Methane fluxes from a shallow peatland lake (3450 m a.s.l., 1.6 km(2) in area, maximum depth peatlands to the lake. The shallowness of the water column could be another important favorable factor for methane-containing bubble formation in the sediment and their transportation to the atmosphere. The methane ebullition must have been enhanced by the low atmospheric pressure (ca. 672 hPa) in the high-altitude environment. For a better understanding on the mechanism of methane emission from alpine lakes, more lakes on the Tibetan Plateau should be studied in the future for their methane ebullition. Copyright © 2015 Elsevier B.V. All rights reserved.

  19. Estimates of bacterial and phytoplankton mortality caused by viral lysis and microzooplankton grazing in a shallow eutrophic lake

    Czech Academy of Sciences Publication Activity Database

    Tijdens, M.; van de Waal, D. B.; Slováčková, Hana; Hoogveld, H. L.; Gons, H. J.

    2008-01-01

    Roč. 53, č. 6 (2008), s. 1126-1141 ISSN 0046-5070 R&D Projects: GA MŠk(CZ) 1M0571 Institutional research plan: CEZ:AV0Z60050516 Keywords : cyanobacteria * viruses * mortality Subject RIV: EF - Botanics Impact factor: 2.704, year: 2008

  20. Developmental plasticity of shell morphology of quagga mussels from shallow and deep-water habitats of the Great Lakes.

    Science.gov (United States)

    Peyer, Suzanne M; Hermanson, John C; Lee, Carol Eunmi

    2010-08-01

    The invasive zebra mussel (Dreissena polymorpha) has quickly colonized shallow-water habitats in the North American Great Lakes since the 1980s but the quagga mussel (Dreissena bugensis) is becoming dominant in both shallow and deep-water habitats. While quagga mussel shell morphology differs between shallow and deep habitats, functional causes and consequences of such difference are unknown. We examined whether quagga mussel shell morphology could be induced by three environmental variables through developmental plasticity. We predicted that shallow-water conditions (high temperature, food quantity, water motion) would yield a morphotype typical of wild quagga mussels from shallow habitats, while deep-water conditions (low temperature, food quantity, water motion) would yield a morphotype present in deep habitats. We tested this prediction by examining shell morphology and growth rate of quagga mussels collected from shallow and deep habitats and reared under common-garden treatments that manipulated the three variables. Shell morphology was quantified using the polar moment of inertia. Of the variables tested, temperature had the greatest effect on shell morphology. Higher temperature (approximately 18-20 degrees C) yielded a morphotype typical of wild shallow mussels regardless of the levels of food quantity or water motion. In contrast, lower temperature (approximately 6-8 degrees C) yielded a morphotype approaching that of wild deep mussels. If shell morphology has functional consequences in particular habitats, a plastic response might confer quagga mussels with a greater ability than zebra mussels to colonize a wider range of habitats within the Great Lakes.

  1. Food-web stability signals critical transitions in temperate shallow lakes.

    Science.gov (United States)

    Kuiper, Jan J; van Altena, Cassandra; de Ruiter, Peter C; van Gerven, Luuk P A; Janse, Jan H; Mooij, Wolf M

    2015-07-15

    A principal aim of ecologists is to identify critical levels of environmental change beyond which ecosystems undergo radical shifts in their functioning. Both food-web theory and alternative stable states theory provide fundamental clues to mechanisms conferring stability to natural systems. Yet, it is unclear how the concept of food-web stability is associated with the resilience of ecosystems susceptible to regime change. Here, we use a combination of food web and ecosystem modelling to show that impending catastrophic shifts in shallow lakes are preceded by a destabilizing reorganization of interaction strengths in the aquatic food web. Analysis of the intricate web of trophic interactions reveals that only few key interactions, involving zooplankton, diatoms and detritus, dictate the deterioration of food-web stability. Our study exposes a tight link between food-web dynamics and the dynamics of the whole ecosystem, implying that trophic organization may serve as an empirical indicator of ecosystem resilience.

  2. An application of a water assessment and simulation model in the remediation of the eutrophication capacity of a tropical water system: Case study the Lake Obili in Yaounde (Cameroon

    Directory of Open Access Journals (Sweden)

    Ajeagah Gideon A.

    2017-06-01

    Full Text Available Lake Obili is one of the most famous lakes in the city of Yaounde, Cameroon. Studies carried out in this lake showed that it was hyper eutrophic and therefore it represents a great danger because it is used for aquaculture, tourism and a suitable laboratory for hydro-biological engineering. It is thus very vital to restore this lake ecosystem that singles itself in the heart of the city of Yaounde. This can be greatly facilitated through the use of Water Quality Analysis Simulation Program (WASP of the United State Environmental protection Agency (USEPA. The outcomes of the previous results obtained from EUTRO, a Subroutine of the WASP model specialised in determining eutrophication level have proven that the remediation of this lake can be achievable through the implementation of a wet dredging, the construction and restoration of a wastewater treatment plant, the implementation of environmental incentive policies and the arrangement of the access to the lake. The application of the model is a contribution to the scientific mastery of nutrient flow, lake functioning and possibilities of restauration of highly polluted tropical water bodies subjected to domestic and industrial pollution.

  3. Lithosphere-biosphere interaction at a shallow-sea hydrothermal vent site; Hot Lake, Panarea, Italy

    Science.gov (United States)

    Huang, Chia-I.; Amann, Rudolf; Amend, Jan P.; Bach, Wolfgang; Brunner, Benjamin; Meyerdierks, Anke; Price, Roy E.; Schubotz, Florence; Summons, Roger; Wenzhöfer, Frank

    2010-05-01

    Deep-Sea hydrothermal systems are unique habitats for microbial life with primary production based on chemosynthesis and are considered to be windows to the subsurface biosphere. It is often overlooked, however, that their far more accessible shallow-sea counterparts are also valuable targets to study the effects of hydrothermal activity on geology, seawater chemistry and finally, on microbial life. Such an area of shallow marine hydrothermal venting is observed approximately 2.5 km east of Panarea Island (Sicily, Italy). This system is characterized by fluid temperatures of up to 135° C, gas emissions dominated by CO2 and precipitation of elemental sulfur on the seafloor. In an interdisciplinary project to investigate the influence of geofuels on marine microbiota, sediment cores and pore fluids were sampled for geological and geochemical analyses. An attempt was made to link these geochemical data with a characterization of the microbial community. One of the investigated sites (Lago Caldo, Hot Lake) is an oval-shaped (~10 by 6 meters) shallow (~2.5 m deep) depression covered by elemental sulfur. The sediments in this depression are strongly affected by hydrothermal activity: the pH of pore fluids is in a range between 5 and 6; the salinity is approximately two times higher than seawater. In situ temperatures of 36° C and 74° C (10 cm sediment depth) at two different locations within Hot Lake indicate variability in hydrothermal flux. The sediment surface layer is anoxic, and with increasing depth from the sediment-water interface, sulfate concentrations decrease from ~30 mM to less than 10 mM, whereas sulfide concentrations increase from less than 50 μm to ~1000 μm at 25 cm sediment depth, thus suggesting a higher potential for energy gain based on sulfur disequilibrium. As indicated by the variability in the sediment temperatures at 10 cm, fluid fluxes and mixing with seawater is not found to be uniform at Hot Lake. This is reflected in variability of the

  4. Persistent organic pollutants (POPs) in fish with different feeding habits inhabiting a shallow lake ecosystem.

    Science.gov (United States)

    Barni, María F Silva; Ondarza, Paola M; Gonzalez, Mariana; Da Cuña, Rodrigo; Meijide, Fernando; Grosman, Fabián; Sanzano, Pablo; Lo Nostro, Fabiana L; Miglioranza, Karina S B

    2016-04-15

    The occurrence of persistent organic pollutants (POPs) in the environment can affect organisms inhabiting aquatic systems, in particular shallow lakes that are vulnerable to environmental stressors. This study aimed to assess POPs accumulation and changes at histological and physiological levels in tissues of three fish species with different trophic habits. Gills, brain, muscle, liver and gonads of Odontesthes bonariensis, Oligosarcus jenynsii and Cyphocharax voga were collected from the shallow lake La Peregrina, located in an agricultural area from Argentina. In addition, contaminant levels in surface water (SW), suspended particulate matter (SPM) and bottom sediments (BS) were assessed. Histological lesions were evaluated in fish tissues and levels of vitellogenin (VTG) were assessed in plasma of male fish in order to correlate these alterations with the presence of POPs in the environment. Organochlorine pesticides (OCPs), polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs) were determined by GC-ECD. Biotic and abiotic samples showed the same POPs distribution pattern: OCPs>PCBs>PBDEs. Although tissue distribution of OCPs was species-specific, muscle showed the lowest levels in all species. The most abundant contaminants were endosulfans, suggesting their widespread use in the area. O. bonariensis showed the highest endosulfans levels in liver (184.2-219ngg(-1)wet w), which was associated with the high SPM levels considering this species is a filter feeder. The occurrence of PCBs and PBDEs shows the ubiquity of these pollutants in the area. Histological lesions in gills and liver of O. bonariensis and O. jenynsii, might be related with the high levels of endosulfans in these organs. The detection of VTG in males warns about a possible exposure to estrogenic compounds in the environment. In conclusion, the simultaneous exposure of fish to multiple environmental pollutants leads to different alterations, so measures should be taken in

  5. Continental-scale patterns of nutrient and fish effects on shallow lakes: introduction to a pan-European mesocosm experiment

    NARCIS (Netherlands)

    Stephen, D.; Balayla, D.; Bécares, E.; Collings, S.E.; Fernández-Aláez, C.; Fernández-Aláez, M.; Ferriol, C.; García, P.; Gomá, J.; Gyllström, M.; Hansson, L-A.; Hietala, J.; Kairesalo, T.; Rosa Miracle, M.; Romo, S.; Rueda, J.; Ståhl-Delbanco, A.; Svensson, M.; Vakkilainen, K.; Valentín, M.; van de Bund, W.; Van Donk, E.; Vicente, E.; Villena, M.J.; Moss, B.

    2004-01-01

    1. Shallow lake ecosystems are normally dominated by submerged and emergent plants. Biological stabilising mechanisms help preserve this dominance. The systems may switch to dominance by phytoplankton, however, with loss of submerged plants. This process usually takes place against a background of

  6. Responses of phytoplankton to fish predation and nutrient loading in shallow lakes: a pan-European mesocosm experiment

    NARCIS (Netherlands)

    van de Bund, W.; Romo, S.; Villena, M.J.; Valentín, M.; Van Donk, E.; Vicente, E.; Vakkilainen, K.; Svensson, M.; Stephen, D.; Ståhl-Delbanco, A.; Rueda, J.; Moss, B.; Rosa Miracle, M.; Kairesalo, T.; Hansson, L-A.; Hietala, J.; Gyllström, M.; Goma, J.; García, P.; Fernández-Aláez, M.; Fernández-Aláez, C.; Ferriol, C.; Collings, S.E.; Bécares, E.; Balayla, D.; Alfonso, T.

    2004-01-01

    1. The impacts of nutrients (phosphorus and nitrogen) and planktivorous fish on phytoplankton composition and biomass were studied in six shallow, macrophyte-dominated lakes across Europe using mesocosm experiments. 2. Phytoplankton biomass was more influenced by nutrients than by densities of

  7. Small habitat size and isolation can promote species richness: second-order effects on biodiversity in shallow lakes and ponds

    NARCIS (Netherlands)

    Scheffer, M.; Van Geest, G.J.; Zimmer, K.; Jeppesen, E.; Søndergaard, M.; Butler, M.G.; Hanson, M.A.; Declerck, S.A.J.; De Meester, L.

    2006-01-01

    Contemporary ecological landscape planning is often based on the assumption that small isolated habitat patches sustain relatively few species. Here, we suggest that for shallow lakes and ponds, the opposite can be true for some groups of organisms. Fish communities tend to be poor or even absent in

  8. Mass development of monospecific submerged macrophyte vegetation after the restoration of shallow lakes: roles of light, sediment nutrient levels, and propagule density

    NARCIS (Netherlands)

    Verhofstad, M.J.J.M.; Alirangues, Marta Maria; Reichman, Erik; van Donk, E.; Lamers, L.P.M.; Bakker, E.S.

    2017-01-01

    Abstract After restoration, eutrophicated shallow freshwaters may show mass development of only one or two submerged macrophyte species, lowering biodiversity and hampering recreation. It is unclear which environmental factors govern this high percentage of the volume inhabited (PVI11 PVI: The

  9. Development of constructed wetland using hydroponic biofilter method for purification of hyper-eutrophic lake water; Fueiyoka kosui no joka no tameno suiko seibutsu rokaho wo mochiita jinko shicchi no kaihatsu

    Energy Technology Data Exchange (ETDEWEB)

    Aizaki, M. [Shimane Univ., Matsue (Japan)] Nakasato, H. [Top Ecology Co. Ltd., Tokyo (Japan)

    1997-09-10

    Applying the hydroponic biofilter method as a direct purification method for a hyper-eutrophic lake water, an experiment was carried out at the Tsuchiura Port on Lake Kasumigaura to obtain data for constructing a hydrophilic artificial wetland. Purification of hyper-eutrophic lake water containing a large amount of water blooms in summer was attempted applying the hydroponic biofilter method for which hydrophyte is used. As a result, it was clarified, by applying the hydroponic biofilter method, that capturing effect of suspended substances can be achieved in the rooting zone, captured suspended substances are decomposed at high rate, and the revolved nutrient salt can be absorbed and assimilated by the use of plants having high growth rates. Ipomoea aquatica had the highest removal activity, followed by nasturtium officinal, menthe spicata, and oenanthe javanica. As a result, it became clear that a constructed wetland made with the hydroponic biofilter method can be applied as a direct purifying method for hyper-eutrophic lake water by selecting appropriate plants in accordance with season. 18 refs., 1 fig., 4 tabs.

  10. Effects of internal phosphorus loadings and food-web structure on the recovery of a deep lake from eutrophication

    Science.gov (United States)

    Lepori, Fabio; Roberts, James J.

    2017-01-01

    We used monitoring data from Lake Lugano (Switzerland and Italy) to assess key ecosystem responses to three decades of nutrient management (1983–2014). We investigated whether reductions in external phosphorus loadings (Lext) caused declines in lake phosphorus concentrations (P) and phytoplankton biomass (Chl a), as assumed by the predictive models that underpinned the management plan. Additionally, we examined the hypothesis that deep lakes respond quickly to Lext reductions. During the study period, nutrient management reduced Lext by approximately a half. However, the effects of such reduction on P and Chl a were complex. Far from the scenarios predicted by classic nutrient-management approaches, the responses of P and Chl a did not only reflect changes in Lext, but also variation in internal P loadings (Lint) and food-web structure. In turn, Lint varied depending on basin morphometry and climatic effects, whereas food-web structure varied due to apparently stochastic events of colonization and near-extinction of key species. Our results highlight the complexity of the trajectory of deep-lake ecosystems undergoing nutrient management. From an applied standpoint, they also suggest that [i] the recovery of warm monomictic lakes may be slower than expected due to the development of Lint, and that [ii] classic P and Chl a models based on Lext may be useful in nutrient management programs only if their predictions are used as starting points within adaptive frameworks.

  11. Population dynamics of Chaoborus flavicans and Daphnia spp.: effects on a zooplankton community in a volcanic eutrophic lake with naturally high metal concentrations (L. Monticchio Grande, Southern Italy

    Directory of Open Access Journals (Sweden)

    Letizia GARIBALDI

    2009-02-01

    Full Text Available The response of Daphnia populations to invertebrate predators involves morphological or behavioural changes. Few studies suggest that contaminant aqueous metals, like Cu or Ni at environmentally relevant concentrations, interfere with invertebrate chemical communication systems, such as that which operates between Daphnia and Chaoborus. The objective of our study was to determine if this interference could be also observed in lakes naturally rich in dissolved metals, such as volcanic lake (Lago Grande di Monticchio. This study aimed to assess if natural dissolved metals (e.g., Fe, Mn and Sr could impair the ability of Daphnia pulex and D. galeata × hyalina × cucullata 'complex' populations to respond to Chaoborus kairomones by producing morphological defenses against potential predation, and to understand how Chaoborus predation might affect zooplankton community composition and overall zooplankton density. The predator impact did not result in: i any morphological changes; ii any apparent shift in body size pattern of the prey population; iii any shift in life history traits. Chaoborus accounted for high mortality rates in Cladocera and strongly reduced the chance of individuals to reach maturity. Moreover, highly significant negative correlations between abundance of dominant taxa of zooplankton and C. flavicans were found. The last larval instars of C. flavicans seem to reduce the number of crustaceans, particularly cladocerans and copepod adults and could play an important role in structuring zooplankton communities. Our results suggest that metal inhibition of defence strategies induction probably occurs along the signal transduction pathway in Lake Grande di Monticchio. Impairment of chemosensory response to predatory chemical cues may have widespread ecological consequences in aquatic systems. Chaoborus predation effects can greatly affect both zooplankton biomass and community composition, impact interactions at lower trophic levels

  12. Hydrological regulation drives regime shifts: evidence from paleolimnology and ecosystem modeling of a large shallow Chinese lake.

    Science.gov (United States)

    Kong, Xiangzhen; He, Qishuang; Yang, Bin; He, Wei; Xu, Fuliu; Janssen, Annette B G; Kuiper, Jan J; van Gerven, Luuk P A; Qin, Ning; Jiang, Yujiao; Liu, Wenxiu; Yang, Chen; Bai, Zelin; Zhang, Min; Kong, Fanxiang; Janse, Jan H; Mooij, Wolf M

    2017-02-01

    Quantitative evidence of sudden shifts in ecological structure and function in large shallow lakes is rare, even though they provide essential benefits to society. Such 'regime shifts' can be driven by human activities which degrade ecological stability including water level control (WLC) and nutrient loading. Interactions between WLC and nutrient loading on the long-term dynamics of shallow lake ecosystems are, however, often overlooked and largely underestimated, which has hampered the effectiveness of lake management. Here, we focus on a large shallow lake (Lake Chaohu) located in one of the most densely populated areas in China, the lower Yangtze River floodplain, which has undergone both WLC and increasing nutrient loading over the last several decades. We applied a novel methodology that combines consistent evidence from both paleolimnological records and ecosystem modeling to overcome the hurdle of data insufficiency and to unravel the drivers and underlying mechanisms in ecosystem dynamics. We identified the occurrence of two regime shifts: one in 1963, characterized by the abrupt disappearance of submerged vegetation, and another around 1980, with strong algal blooms being observed thereafter. Using model scenarios, we further disentangled the roles of WLC and nutrient loading, showing that the 1963 shift was predominantly triggered by WLC, whereas the shift ca. 1980 was attributed to aggravated nutrient loading. Our analysis also shows interactions between these two stressors. Compared to the dynamics driven by nutrient loading alone, WLC reduced the critical P loading and resulted in earlier disappearance of submerged vegetation and emergence of algal blooms by approximately 26 and 10 years, respectively. Overall, our study reveals the significant role of hydrological regulation in driving shallow lake ecosystem dynamics, and it highlights the urgency of using multi-objective management criteria that includes ecological sustainability perspectives when

  13. The hydrological and environmental evolution of shallow Lake Melincué, central Argentinean Pampas, during the last millennium

    Science.gov (United States)

    Guerra, Lucía; Piovano, Eduardo L.; Córdoba, Francisco E.; Sylvestre, Florence; Damatto, Sandra

    2015-10-01

    Lake Melincué, located in the central Pampean Plains of Argentina, is a shallow (∼4 m), subsaline lake (TDS > 2000 ppm), highly sensitive to hydrological changes. The modern shallow lake system is composed of: (a) a supralittoral area, which includes a narrow mudflat, a vegetated mudflat and wetlands subenvironments; and (b) the main water body, comprising lacustrine marginal and inner areas. The development and extension of these subenvironments are strongly conditioned upon lake surface fluctuations. Past environmental changes were reconstructed through sedimentological, physical and geochemical proxy analyses of two short sedimentary cores (∼127 cm). Well-constrained 210Pb ages profiles were modeled and radiocarbon chronologies were determined, covering a period from ∼AD 800 to the present. The analyzed sedimentary cores from Lake Melincué allowed for the reconstruction of past hydrological scenarios and associated environmental variability, ranging from extremely low lake levels during dry phases to pronounced highstands at wet periods. The paleohydrological reconstruction revealed very shallow conditions in the period between AD 806 and AD 1880, which was registered by massive deposits with low organic matter. Relatively wetter phases disrupting this dry period were represented by organic matter increases. A major wet phase was registered by AD 1454, after the end of the Medieval Climate Anomaly. A subsequent abrupt shift from this wet phase to drier conditions could be matching the transition between the end of the Medieval Climatic Anomaly and the beginning of the Little Ice Age. The occurrence of sedimentary hiatuses between AD 1492 and AD 1880 in Melincué sequence could correspond to intensive droughts during the Little Ice Age. After AD 1880, banded and laminated, autochthonous, organic matter-rich sediments registered an important lacustrine transgression and the onset of a permanent shallow lake, corresponding to the beginning of the current

  14. Herbivory of Omnivorous Fish Shapes the Food Web Structure of a Chinese Tropical Eutrophic Lake: Evidence from Stable Isotope and Fish Gut Content Analyses

    Directory of Open Access Journals (Sweden)

    Jian Gao

    2017-01-01

    Full Text Available Studies suggest that, unlike the situation in temperate lakes, high biomasses of omnivorous fish are maintained in subtropical and tropical lakes when they shift from a turbid phytoplankton-dominated state to a clear water macrophyte-dominated state, and the predation pressure on large-bodied zooplankton therefore remains high. Whether this reflects a higher degree of herbivory in warm lakes than in temperate lakes is debatable. We combined food web studies using stable isotopes with gut content analyses of the most dominant fish species to elucidate similarities and differences in food web structure between a clear water macrophyte-dominated basin (MDB and a turbid phytoplankton-dominated basin (PDB of Huizhou West Lake, a shallow tropical Chinese lake. The δ13C–δ15N biplot of fish and invertebrates revealed community-wide differences in isotope-based metrics of the food webs between MDB and PDB. The range of consumer δ15N (NR was lower in MDB than in PDB, indicating shorter food web length in MDB. The mean nearest neighbor distance (MNND and standard deviation around MNND (SDNND were higher in MDB than in PDB, showing a markedly low fish trophic overlap and a more uneven packing of species in niches in MDB than in PDB. The range of fish δ13C (CR of consumers was more extensive in MDB than in PDB, indicating a wider feeding range for fish in MDB. Mixing model results showed that macrophytes and associated periphyton constituted a large fraction of basal production sources for the fish in MDB, while particulate organic matter (POM contributed a large fraction in PDB. In MDB, the diet of the dominant fish species, crucian carp (Carassius carassius, consisted mainly of vegetal matter (macrophytes and periphyton and zooplankton, while detritus was the most important food item in PDB. Our results suggest that carbon from macrophytes with associated periphyton may constitute an important food resource for omnivorous fish, and this may strongly

  15. Global warming: Design of a flow-through shallow lake mesocosm climate experiment

    DEFF Research Database (Denmark)

    Liboriussen, L.; Landkildehus, F.; Meerhoff, M.

    2005-01-01

    design details, operating characteristics, and background information on a currently operating experimental flow-through mesocosm system that allows investigation of the interactions between simulated climate warming and eutrophication and their impacts on biological structure and ecosystem processes...

  16. Integrated ecological and chemical food web accumulation modeling explains PAH temporal trends during regime shifts in a shallow lake.

    Science.gov (United States)

    Kong, Xiangzhen; He, Wei; Qin, Ning; Liu, Wenxiu; Yang, Bin; Yang, Chen; Xu, Fuliu; Mooij, Wolf M; Koelmans, Albert A

    2017-08-01

    Shallow lakes can switch suddenly from a turbid situation with high concentrations of phytoplankton and other suspended solids to a vegetated state with clear water, and vice versa. These alternative stable states may have a substantial impact on the fate of hydrophobic organic compounds (HOCs). Models that are fit to simulate impacts from these complex interactions are scarce. We developed a contaminant fate model which is linked to an ecosystem model (PCLake) for shallow lakes. This integrated model was successful in simulating long-term dynamics (1953-2012) of representative polycyclic aromatic hydrocarbons (PAHs) in the main biotic and abiotic components in a large shallow lake (Chaohu in China), which has undergone regime shifts in this period. Historical records from sediment cores were used to evaluate the model. The model revealed that regime shifts in shallow lakes had a strong impact on the fate of less hydrophobic compounds due to the large storage capacity of macrophytes, which accumulated up to 55.6% of phenanthrene in the clear state. The abrupt disappearance of macrophytes after the regime shift resulted in a sudden change in phenanthrene distribution, as the sediment became the major sink. For more hydrophobic compounds such as benzo(a)pyrene, the modeled impact of the regime shift was negligible for the whole environment, yet large for biotic compartments. This study is the first to provide a full mechanistic analysis of the impact of regime shifts on the fate of PAHs in a real lake ecosystem. Copyright © 2017 Elsevier Ltd. All rights reserved.

  17. Spring temperature variability and eutrophication history inferred from sedimentary pigments in the varved sediments of Lake Żabińskie, north-eastern Poland, AD 1907-2008

    Science.gov (United States)

    Amann, Benjamin; Lobsiger, Simon; Fischer, Daniela; Tylmann, Wojciech; Bonk, Alicja; Filipiak, Janusz; Grosjean, Martin

    2014-12-01

    Varved lake sediments are excellent natural archives providing quantitative insights into climatic and environmental changes at very high resolution and chronological accuracy. However, due to the multitude of responses within lake ecosystems it is often difficult to understand how climate variability interacts with other environmental pressures such as eutrophication, and to attribute observed changes to specific causes. This is particularly challenging during the past 100 years when multiple strong trends are superposed. Here we present a high-resolution multi-proxy record of sedimentary pigments and other biogeochemical data from the varved sediments of Lake Żabińskie (Masurian Lake District, north-eastern Poland, 54°N-22°E, 120 m a.s.l.) spanning AD 1907 to 2008. Lake Żabińskie exhibits biogeochemical varves with highly organic late summer and winter layers separated by white layers of endogenous calcite precipitated in early summer. The aim of our study is to investigate whether climate-driven changes and anthropogenic changes can be separated in a multi-proxy sediment data set, and to explore which sediment proxies are potentially suitable for long quantitative climate reconstructions. We also test if convoluted analytical techniques (e.g. HPLC) can be substituted by rapid scanning techniques (visible reflectance spectroscopy VIS-RS; 380-730 nm). We used principal component analysis and cluster analysis to show that the recent eutrophication of Lake Żabińskie can be discriminated from climate-driven changes for the period AD 1907-2008. The eutrophication signal (PC1 = 46.4%; TOC, TN, TS, Phe-b, high TC/CD ratios total carotenoids/chlorophyll-a derivatives) is mainly expressed as increasing aquatic primary production, increasing hypolimnetic anoxia and a change in the algal community from green algae to blue-green algae. The proxies diagnostic for eutrophication show a smooth positive trend between 1907 and ca 1980 followed by a very rapid increase

  18. Sedimentary records of sewage pollution using faecal markers in contrasting peri-urban shallow lakes

    Energy Technology Data Exchange (ETDEWEB)

    Vane, C.H., E-mail: chv@bgs.ac.uk [British Geological Survey, Keyworth, Nottingham, NG12 5GG (United Kingdom); Kim, A.W. [British Geological Survey, Keyworth, Nottingham, NG12 5GG (United Kingdom); McGowan, S. [School of Geography, University of Nottingham, University Park, Nottingham, NG7 2RD (United Kingdom); Leng, M.J.; Heaton, T.H.E.; Kendrick, C.P. [NERC Isotope Geosciences Laboratory, British Geological Survey, Keyworth, Nottingham, NG12 5GG (United Kingdom); Coombs, P. [British Geological Survey, Keyworth, Nottingham, NG12 5GG (United Kingdom); Yang, H. [Environmental Change Research Centre, University College London, WC1 6BT (United Kingdom); Swann, G.E.A. [NERC Isotope Geosciences Laboratory, British Geological Survey, Keyworth, Nottingham, NG12 5GG (United Kingdom)

    2010-12-15

    Sewage contamination in shallow lake sediments is of concern because the pathogens, organic matter and nutrients contribute to the deterioration of the water-bodies' health and ecology. Sediment cores from three shallow lakes (Coneries, Church and Clifton Ponds) within Attenborough nature reserve located downstream of sewage treatment works were analysed for TOC, C/N, {delta}{sup 13}C, {delta}{sup 15}N, bacterial coliforms and faecal sterols. {sup 210}Pb and {sup 137}Cs activities were used to date the sediments. Elemental analysis suggests that the source of organic matter was algal and down profile changes in {delta}{sup 13}C indicate a possible decrease in productivity with time which could be due to improvements in sewage treatment. {delta}{sup 15}N for Coneries Pond are slightly higher than those observed in Church or Clifton and are consistent with a sewage-derived nitrate source which has been diluted by non-sewage sources of N. The similarity in {delta}{sup 15}N values (+ 12 per mille to + 10 per mille ) indicates that the three ponds were not entirely hydrologically isolated. Analysis by gas chromatography/mass spectrometry (GC/MS) reveals that Coneries Pond had sterol concentrations in the range 20 to 30 {mu}g/g (dry wt.), whereas, those from Clifton and Church Ponds were lower. The highest concentrations of the human-sourced sewage marker 5{beta}-coprostanol were observed in the top 40 cm of Coneries Pond with values up to 2.2 {mu}g/g. In contrast, Church and Clifton Pond sediments contain only trace amounts throughout. Down-profile comparison of 5{beta}-coprostanol/cholesterol, 5{beta}-coprostanol/(5{beta}-coprostanol + 5{alpha}-cholestanol) and 5{beta}-epicoprostanol/coprostanol as well as 5{alpha}-cholestanol/cholesterol suggests that Coneries Pond has received appreciable amounts of faecal contamination. Examination of 5{beta}-stigmastanol (marker for herbivorous/ruminant animals) down core concentrations suggests a recent decrease in manure

  19. 200 kHz Sonication of Mixed-Algae Suspension from a Eutrophic Lake: The Effect on the Caution vs. Outbreak Bloom Alert Levels

    Directory of Open Access Journals (Sweden)

    Andinet Tekile

    2017-11-01

    Full Text Available For effective ultrasonic algae removal, several studies have considered the ultrasound equipment linked factors, such as power and frequency. However, studies on the response of mixed algal cultures and associated water quality parameters to ultrasound are limited. In this lab-scale sonication, the removal of cyanobacteria at a pre-set frequency of 200 kHz on mixed algae suspensions collected from a eutrophic lake was investigated. The caution (17.5 µg/L and outbreak (1450 µg/L alert levels in terms of chlorophyll-a (Chl-a concentrations of the initial samples were each sonicated for 10, 15, and 20 min, and then kept in an incubator. Fifteen minutes of sonication resulted in best removal efficiency of 0.94 and 0.77, at an ultrasonic dose of 30 kWh/m3 at the outbreak and caution level concentrations, respectively. Immediately after 15 min sonication, and after standing in the incubator for a day, chlorophyll-a removal efficiencies of 0.28 and 0.90 were achieved in the outbreak level, respectively, and the matching removal efficiencies for the caution level were 0.23 and 0.64. Even though the removal was substantial in both cases, the final 147 µg/L chlorophyll-a concentration of the outbreak, which is itself still in the outbreak level range, shows that ultrasonication is not effective to satisfactorily remove algae from a concentrated suspension. Total dissolved nitrogen and chemical oxygen demand were reduced, overall, due to sonication. However, total dissolved phosphorus of the concentrated level was increased during the treatment. Although sonication needs further replicated experimental testing in whole-lake systems, our results show that 200 kHz sonication was able to reduce chlorophyll-a concentrations in small-scale laboratory tests.

  20. Spatial distribution and risk assessment of heavy metals and As pollution in the sediments of a shallow lake.

    Science.gov (United States)

    Deng, Jiancai; Wang, Yuansheng; Liu, Xin; Hu, Weiping; Zhu, Jinge; Zhu, Lin

    2016-05-01

    The concentrations and spatial distributions of eight heavy metals in surface sediments and sediment core samples from a shallow lake in China were investigated to evaluate the extent of the contamination and potential ecological risks. The results showed that the heavy metal concentrations were higher in the northern and southwestern lake zones than those in the other lake zones, with lower levels of As, Hg, Zn, Cu, Pb, Cr, and Ni primarily observed in the central and eastern lake regions and Cd primarily confined to areas surrounding the lake. The concentrations of the eight heavy metals in the sediment profiles tended to decrease with increasing sediment depth. The contents of Ni, Cu, Zn, Pb, and Cd in the surface sediment were approximately 1.23-18.41-fold higher than their background values (BVs), whereas the contents of Cr, As, and Hg were nearly identical to their BVs. The calculated pollution load index (PLI) suggested that the surface sediments of this lake were heavily polluted by these heavy metals and indicated that Cd was a predominant contamination factor. The comprehensive potential ecological risk index (PERI) in the surface sediments ranged from 99.2 to 2882.1, with an average of 606.1. Cd contributed 78.7 % to the PERI, and Hg contributed 8.4 %. Multivariate statistical analyses revealed that the surface sediment pollution with heavy metals mainly originated from industrial wastewater discharged by rivers located in the western and northwestern portion of the lake.

  1. The altered ecology of Lake Christina: A record of regime shifts, land-use change, and management from a temperate shallow lake

    International Nuclear Information System (INIS)

    Theissen, Kevin M.; Hobbs, William O.; Hobbs, Joy M. Ramstack; Zimmer, Kyle D.; Domine, Leah M.; Cotner, James B.; Sugita, Shinya

    2012-01-01

    We collected two sediment cores and modern submerged aquatic plants and phytoplankton from two sub-basins of Lake Christina, a large shallow lake in west-central Minnesota, and used stable isotopic and elemental proxies from sedimentary organic matter to explore questions about the pre- and post-settlement ecology of the lake. The two morphologically distinct sub-basins vary in their sensitivities to internal and external perturbations offering different paleoecological information. The record from the shallower and much larger western sub-basin reflects its strong response to internal processes, while the smaller and deeper eastern sub-basin record primarily reflects external processes including important post-settlement land-use changes in the area. A significant increase in organic carbon accumulation (3–4 times pre-settlement rates) and long-term trends in δ 13 C, organic carbon to nitrogen ratios (C/N), and biogenic silica concentrations shows that primary production has increased and the lake has become increasingly phytoplankton-dominated in the post-settlement period. Significant shifts in δ 15 N values reflect land-clearing and agricultural practices in the region and support the idea that nutrient inputs have played an important role in triggering changes in the trophic status of the lake. Our examination of hydroclimatic data for the region over the last century suggests that natural forcings on lake ecology have diminished in their importance as human management of the lake increased in the mid-1900s. In the last 50 years, three chemical biomanipulations have temporarily shifted the lake from the turbid, algal-dominated condition into a desired clear water regime. Two of our proxies (δ 13 C and BSi) measured from the higher resolution eastern basin record responded significantly to these known regime shifts. -- Highlights: ► We explore the sediment geochemistry from Lake Christina's two distinct sub-basins. ► Our geochemical data show

  2. Temporal-spatial variations and influencing factors of nitrogen in the shallow groundwater of the nearshore vegetable field of Erhai Lake, China.

    Science.gov (United States)

    Chen, Anqiang; Lei, Baokun; Hu, Wanli; Wang, Hongyuan; Zhai, Limei; Mao, Yanting; Fu, Bin; Zhang, Dan

    2018-02-01

    Nitrogen export from the nearshore vegetable field of Erhai Lake seriously threatens the water quality of Erhai Lake, which is the second largest highland freshwater lake in Yunnan Province, China. Among the nitrogen flows into Erhai Lake, shallow groundwater migration is a major pathway. The nitrogen variation and influencing factors in the shallow groundwater of the nearshore vegetable field of Erhai Lake are not well documented. A 2-year field experiment was conducted to determine the concentrations of nitrogen species in the shallow groundwater and their influencing factors in the nearshore vegetable field of Erhai Lake. The results showed that concentrations of TN, NO 3 - -N, and NO 2 - -N gradually increased with increasing elevation and distance from Erhai Lake, but the opposite was observed for NH 4 + -N in the shallow groundwater. The concentrations of nitrogen species in the rainy season were greater than those in the dry season. NO 3 - -N accounted for more than 79% of total nitrogen in shallow groundwater. Redundancy analysis showed that more than 70% of the temporal and spatial variations of nitrogen concentrations in the shallow groundwater were explained by shallow groundwater depth, and only approximately 10% of variation was explained by the factors of soil porosity, silt clay content of soil, and NH 4 + -N and NO 3 - -N concentrations of soil (p shallow groundwater depth had more notable effects on nitrogen concentrations in the shallow groundwater than other factors. This result will strongly support the need for further research regarding the management practices for reducing nitrogen concentrations in shallow groundwater.

  3. Remote Sensing and Shallow Geophysical Investigations on Moghra Lake in Northeastern Qattarra Depression, Western Desert, Egypt

    Science.gov (United States)

    Khan, S. D.; Fathy, M. S.; Azeem, M. A.

    2012-12-01

    covered by about 2 m of lacustrine sediments of post-Miocene age in the east side and by recent eolian dunes in the west. These sediments are characterized by shallowing upward, horizontal to cross-bedded with an unconformity in between. The eastern end of the paleochannel surveyed by GPR is covered by recent sand dunes followed by an ephemeral stream that feeds the current lake. Field observations suggest that the movement of sand dunes in the northeast direction may have blocked the paleo-channel. A two meters deep trench was dug to confirm the GPR findings. Regional gravity mapping of this area also shows major gravity anomalies. More work is planned to carry out additional high resolution potential field surveys in conjunction with remote sensing and GPR studies to understand the paleo-drainage of this area. Identifying the exact track of the paleo-channels will help reconstructing of paleo drainage of this region and may help in mapping groundwater, this will be very important for the development of this rapidly expanding desert area.

  4. Three Dimensional Seismic Tomography of the Shallow Subsurface Structure Under the Meihua Lake in Ilan, Northeastern Taiwan

    Science.gov (United States)

    Shih, R.

    2008-12-01

    The island of Taiwan is located at an ongoing collision boundary between two plates. The Philippine Sea plate and the Eurasian plate collided at the Longitudinal Valley of eastern Taiwan, and the Philippine Sea plate subducted northward beneath the Eurasian plate along the Ryukyu trench in eastern Taiwan at the Hualien area. Further northward in the island, the opening Okinawa trough ended at the Ilan area in northeastern Taiwan. The Ilan area is over populated and potentially able to produce large earthquake; however, since that are is densely covered with forests, due to lack of geologic and geomorphologic evidences, known active faults are still unclear. Recently, a series of topographic offsets of several meters distributed in a zone were found by using the LiDAR DTM data, indicating active normal faulting was activated in the past. Besides, several small sag ponds were mapped to support the active normal faulting activities. Later on, core borings in one of the small ponds (the Meihua Lake, diameter of about 700m) were conducted and the records showed obvious difference of depths in the adjacent boreholes at a very short distance. In order to realize the variation of the distribution of sediments under the Meihua Lake, we conducted a 3d seismic tomography survey at the lake, hopefully to help to verify the faults. In this paper, we will show results of using a 120-channel shallow seismic recording system for mapping the shallow subsurface structure of sediments under the Meihua Lake. During the experiment, we deployed the geophone groups of three geophones at every 6m along the bank of the lake and fired the shots at every 80m around the lake. An impactor of energy 2200 joule per shot was used as a seismic source. We stacked the energy at each shot point around 60 times for receiving clear signals. Since the total extension of recording system is 720m, about one third of the perimeter around the lake, 2,200m, we moved the geophone deployments 3 times to

  5. Greenhouse gas fluxes of a shallow lake in south-central North Dakota, USA

    Science.gov (United States)

    Tangen, Brian; Finocchiaro, Raymond; Gleason, Robert A.; Dahl, Charles F.

    2016-01-01

    Greenhouse gas (GHG) fluxes of aquatic ecosystems in the northern Great Plains of the U.S. represent a significant data gap. Consequently, a 3-year study was conducted in south-central North Dakota, USA, to provide an initial estimate of GHG fluxes from a large, shallow lake. Mean GHG fluxes were 0.02 g carbon dioxide (CO2) m−2 h−1, 0.0009 g methane (CH4) m−2 h−1, and 0.0005 mg nitrous oxide (N2O) m−2 h−1. Fluxes of CO2 and CH4 displayed temporal and spatial variability which is characteristic of aquatic ecosystems, while fluxes of N2O were consistently low throughout the study. Comparisons between results of this study and published values suggest that mean daily fluxes of CO2, CH4, and N2O fromLong Lakewere low, particularly when compared to the well-studied prairie pothole wetlands of the region. Similarly, cumulative seasonal CH4 fluxes, which ranged from 2.68–7.58 g CH4 m−2, were relatively low compared to other wetland systems of North America. The observed variability among aquatic ecosystems underscores the need for further research.

  6. Soil erosion and sedimentation rates in a small eutrophic lake in southern Chile estimated by 210Pb isotope analysis

    International Nuclear Information System (INIS)

    Cisternas, M.; Urrutia, R.; Araneda, A.; Debels, P.; Rios, F.

    1999-01-01

    The purpose of this research is to study the effects of historical land use patterns on soil erosion within the San Pedro Lake watershed (Concepcion, VIII Region, Chile). To this end, a geochronological reconstruction of the last 50 years was accomplished by 210 Pb isotope and photo-interpretation analysis through the use of GIS. The erosion rate has varied from 0.40 t ha -1 y -1 in 1955 to 0.86 t ha -1 y -1 in 1994. The decrease in native forest was closely coupled with the increase in exotic forestry. The Total Change, meaning the land use change without considering each typology, shows a constant trend indicating a greater degree of anthropogenic intervention. As opposed to the expected, there is no relationship between land use typologies and erosion rates, however it is possible to recognise some degree of dependency between Total Change and erosion values. It is concluded that over the last 50 years the soil erosion processes in the San Pedro Lake watershed may have been more regulated more by land use changes than by land use typologies themselves. (author)

  7. Multimedia fate modeling of perfluorooctanoic acid (PFOA) and perfluorooctane sulphonate (PFOS) in the shallow lake Chaohu, China.

    Science.gov (United States)

    Kong, Xiangzhen; Liu, Wenxiu; He, Wei; Xu, Fuliu; Koelmans, Albert A; Mooij, Wolf M

    2018-06-01

    Freshwater shallow lake ecosystems provide valuable ecological services to human beings. However, these systems are subject to severe contamination from anthropogenic sources. Per- and polyfluoroalkyl substances (PFASs), including perfluorooctanoic acid (PFOA) and perfluorooctane sulphonate (PFOS), are among the contaminants that have received substantial attention, primarily due to abundant applications, environment persistence, and potential threats to ecological and human health. Understanding the environmental behavior of these contaminants in shallow freshwater lake environments using a modeling approach is therefore critical. Here, we characterize the fate, transport and transformation of both PFOA and PFOS in the fifth largest freshwater lake in China (Chaohu) during a two-year period (2013-2015) using a fugacity-based multimedia fate model. A reasonable agreement between the measured and modeled concentrations in various compartments confirms the model's reliability. The model successfully quantifies the environmental processes and identifies the major sources and input pathways of PFOA and PFOS to the Chaohu water body. Sensitivity analysis reveals the critical role of nonlinear Freundlich sorption, which contributes to a variable fraction of the model true uncertainty in different compartments (8.1%-93.6%). Through additional model scenario analyses, we further elucidate the importance of nonlinear Freundlich sorption that is essential for the reliable model performance. We also reveal the distinct composition of emission sources for the two contaminants, as the major sources are indirect soil volatilization and direct release from human activities for PFOA and PFOS, respectively. The present study is expected to provide implications for local management of PFASs pollution in Lake Chaohu and to contribute to developing a general model framework for the evaluation of PFASs in shallow lakes. Copyright © 2018 Elsevier Ltd. All rights reserved.

  8. Assessment of the effect of anthropogenic pollution on the ecology of small shallow lakes using the palaeolimnological approach

    Directory of Open Access Journals (Sweden)

    Tiiu Koff

    2016-11-01

    Full Text Available Palaeolimnological techniques were utilized to determine the extent of the effect of anthropogenic pollutants or other environmental stressors on three lake ecosystems over the last 200 years. The ecology of the study sites has experienced significant changes due to various activities such as (1 extensive catchment drainage and using poisoning as a fish management measure, (2 seepage of urban waste water due to establishment and growth of a town and (3 artificial inflow of oil-shale mining waters. Sediment geochemical composition, fossil pigments and Cladocera remains from the sediment cores were analysed to demonstrate that sufficient information can be derived from sediments to permit a historical reconstruction. The integrated use of archival maps, historical records and lake monitoring data confirmed links to anthropogenic pollutants, primarily on the catchment level. The examples show how the sediment indicators provide unique insights into the causes and temporal dynamics of lake ecosystem changes relevant for environmental management decisions. This study demonstrates that palaeolimnology has great potential to assist in eutrophication assessment and management efforts in waterbodies.

  9. Improving the accuracy of estimation of eutrophication state index ...

    African Journals Online (AJOL)

    Trophic Level Index (TLI) is oen used to assess the general eutrophication state of inland lakes in water science, technology, and engineering. In this paper, a data-driven inland-lake eutrophication assessment method was proposed by using an articial neural network (ANN) to build relationships from remote sensing data ...

  10. Spatial distributions, fractionation characteristics, and ecological risk assessment of trace elements in sediments of Chaohu Lake, a large eutrophic freshwater lake in eastern China.

    Science.gov (United States)

    Wu, Lei; Liu, Guijian; Zhou, Chuncai; Liu, Rongqiong; Xi, Shanshan; Da, Chunnian; Liu, Fei

    2018-01-01

    The concentrations, spatial distribution, fractionation characteristics, and potential ecological risks of trace elements (Cu, Pb, Zn, Cr, Ni, and Co) in the surface sediment samples collected from 32 sites in Chaohu Lake were investigated. The improved BCR sequential extraction procedure was applied to analyze the chemical forms of trace elements in sediments. The enrichment factor (EF), sediment quality guidelines (SQGs), potential ecological risk index (PERI), and risk assessment code (RAC) were employed to evaluate the pollution levels and the potential ecological risks. The results found that the concentrations of Cu, Pb, Zn, Cr, Ni, and Co in the surface sediments were 78.59, 36.91, 161.84, 98.87, 38.92, and 10.09 mg kg -1 , respectively. The lower concentrations of Cu, Pb, Zn, Cr, and Ni were almost found in the middle part of the lake, while Co increased from the western toward the eastern parts of the lake. Cr, Ni, Co, and Zn predominantly existed in the residual fractions, with the average values of 76.35, 59.22, 45.60, and 44.30%, respectively. Cu and Pb were mainly combined with Fe/Mn oxides in reducible fraction, with the average values of 66.4 and 69.1%, respectively. The pollution levels were different among the selected elements. Cu had the highest potential ecological risk, while Cr had the lowest potential ecological risk.

  11. Chromophoric dissolved organic matter of black waters in a highly eutrophic Chinese lake: Freshly produced from algal scums?

    Science.gov (United States)

    Zhou, Yongqiang; Jeppesen, Erik; Zhang, Yunlin; Niu, Cheng; Shi, Kun; Liu, Xiaohan; Zhu, Guangwei; Qin, Boqiang

    2015-12-15

    Field campaigns and an incubation experiment were conducted to evaluate the sources of chromophoric dissolved organic matter (CDOM) in black water spots in highly polluted regions of the Chinese Lake Taihu. A significant positive correlation (pCDOM absorption coefficient a(350), indicating that algae degradation was likely the primary source of CDOM in black waters. This is supported by our field results that Chl-a, a(350) and the spectral slope ratio (SR) were significantly higher in the black water samples than in the regular samples (pCDOM source where a(350) increased with decreasing Chl-a concentrations. After seven days' incubation, a 72.2% decrease and a 74.9% increase were recorded for Chl-a and a(350), respectively, relative to the initial values. Parallel factor analysis identified five fluorescent components. The maximal fluorescence intensity (Fmax) of tryptophan-like C1 and microbial humic-like C3 of black water samples was significantly higher than in the regular water samples (pCDOM source in black water spots. Copyright © 2015 Elsevier B.V. All rights reserved.

  12. Enhanced Input of Terrestrial Particulate Organic Matter Reduces the Resilience of the Clear-Water State of Shallow Lakes: A Model Study

    NARCIS (Netherlands)

    Lischke, B.; Hilt, S.; Janse, J.H.; Kuiper, J.J.; Mehner, T.; Mooij, W.M.; Gaedke, U.

    2014-01-01

    The amount of terrestrial particulate organic matter (t-POM) entering lakes is predicted to increase as a result of climate change. This may especially alter the structure and functioning of ecosystems in small, shallow lakes which can rapidly shift from a clear-water, macrophyte-dominated into a

  13. Hurricane effects on a shallow lake ecosystem and its response to a controlled manipulation of water level.

    Science.gov (United States)

    Havens, K E; Jin, K R; Rodusky, A J; Sharfstein, B; Brady, M A; East, T L; Iricanin, N; James, R T; Harwell, M C; Steinman, A D

    2001-04-04

    In order to reverse the damage to aquatic plant communities caused by multiple years of high water levels in Lake Okeechobee, Florida (U.S.), the Governing Board of the South Florida Water Management District (SFWMD) authorized a "managed recession" to substantially lower the surface elevation of the lake in spring 2000. The operation was intended to achieve lower water levels for at least 8 weeks during the summer growing season, and was predicted to result in a large-scale recovery of submerged vascular plants. We treated this operation as a whole ecosystem experiment, and assessed ecological responses using data from an existing network of water quality and submerged plant monitoring sites. As a result of large-scale discharges of water from the lake, coupled with losses to evaporation and to water supply deliveries to agriculture and other regional users, the lake surface elevation receded by approximately 1 m between April and June. Water depths in shoreline areas that historically supported submerged plant communities declined from near 1.5 m to below 0.5 m. Low water levels persisted for the entire summer. Despite shallow depths, the initial response (in June 2000) of submerged plants was very limited and water remained highly turbid (due at first to abiotic seston and later to phytoplankton blooms). Turbidity decreased in July and the biomass of plants increased. However, submerged plant biomass did not exceed levels observed during summer 1999 (when water depths were greater) until August. Furthermore, a vascular plant-dominated assemblage (Vallisneria, Potamogeton, and Hydrilla) that occurred in 1999 was replaced with a community of nearly 98% Chara spp. (a macro-alga) in 2000. Hence, the lake"s submerged plant community appeared to revert to an earlier successional stage despite what appeared to be better conditions for growth. To explain this unexpected response, we evaluated the impacts that Hurricane Irene may have had on the lake in the previous

  14. Sources and behaviour of nitrogen compounds in the shallow groundwater of agricultural areas (Poyang Lake basin, China).

    Science.gov (United States)

    Soldatova, Evgeniya; Guseva, Natalia; Sun, Zhanxue; Bychinsky, Valeriy; Boeckx, Pascal; Gao, Bai

    2017-07-01

    Nitrogen contamination of natural water is a typical problem for various territories throughout the world. One of the regions exposed to nitrogen pollution is located in the Poyang Lake basin. As a result of agricultural activity and dense population, the shallow groundwater of this area is characterised by a high concentration of nitrogen compounds, primarily NO 3 - , with the concentration varying from 0.1mg/L to 206mg/L. Locally, high ammonium content occurs in the shallow groundwater with low reduction potential Eh (shallow groundwater of the Poyang Lake basin has Eh>100mV. To identify sources of nitrogen species and the factors that determine their behaviour, the dual stable isotope approach (δ 15 N and δ 18 О) and physical-chemical modelling were applied. Actual data were collected by sampling shallow groundwater from domestic water supply wells around the lake. The δ 18 О values from -4.1‰ to 13.9‰ with an average value of 5.3 permille indicate a significant influence of nitrification on nitrogen balance. The enrichment of nitrate with the 15 N isotope indicates that manure and domestic sewage are the principal sources of nitrogen compounds. Inorganic nitrogen speciation and thermodynamic calculations demonstrate the high stability of nitrate in the studied groundwater. Computer simulation and field observations indicate the reducing conditions formed under joint effects of anthropogenic factors and appropriate natural conditions, such as the low-level topography in which decreased water exchange rate can occur. The simulation also demonstrates the growth in pH of the groundwater as a consequence of fertilisation, which, in turn, conduced to the clay mineral formation at lower concentrations of aqueous clay-forming components than the ones under the natural conditions. Copyright © 2017 Elsevier B.V. All rights reserved.

  15. Establishment of stream nutrient criteria by comparing reference conditions with ecological thresholds in a typical eutrophic lake basin.

    Science.gov (United States)

    Cao, Xiaofeng; Wang, Jie; Jiang, Dalin; Sun, Jinhua; Huang, Yi; Luan, Shengji

    2017-12-13

    The establishment of numeric nutrient criteria is essential to aid the control of nutrient pollution and for protecting and restoring healthy ecological conditions. However, it's necessary to determine whether regional nutrient criteria can be defined in stream ecosystems with a poor ecological status. A database of periphytic diatom samples was collected in July and August 2011 and 2012. In total 172 samples were included in the database with matching environmental variables. Here, percentile estimates, nonparametric change-point analysis (nCPA) and Threshold Indicator Taxa ANalysis (TITAN) were conducted to detect the reference conditions and ecological thresholds along a total nitrogen (TN) and total phosphorus (TP) gradient and ammonia nitrogen (NH 3 -N) for the development of nutrient criteria in the streams of the Lake Dianchi basin. The results highlighted the possibility of establishing regional criteria for nutrient concentrations, which we recommended to be no more than 1.39 mg L -1 for TN, 0.04 mg L -1 for TP and 0.17 mg L -1 for NH 3 -N to prevent nuisance growths of tolerant taxa, and 0.38 mg L -1 for TN, 0.02 mg L -1 for TP and 0.02 mg L -1 for NH 3 -N to maintain high quality waters in streams. Additionally, the influence of excessive background nutrient enrichment on the threshold response, and the ecological interaction with other stressors (HQI, etc.) in the nutrient dynamic process need to be considered to establish the eventual nutrient criteria, regardless of which technique is applied.

  16. Will the Displacement of Zebra Mussels by Quagga Mussels Increase Water Clarity in Shallow Lakes during Summer? Results from a Mesocosm Experiment

    OpenAIRE

    Mei, Xueying; Zhang, Xiufeng; Kassam, Sinan-Saleh; Rudstam, Lars G.

    2016-01-01

    Zebra mussels (Dreissena polymorpha) are known to increase water clarity and affect ecosystem processes in invaded lakes. During the last decade, the conspecific quagga mussels (D. rostriformis bugensis) have displaced zebra mussels in many ecosystems including shallow lakes such as Oneida Lake, New York. In this study, an eight-week mesocosm experiment was conducted to test the hypothesis that the displacement of zebra mussels by quagga mussels leads to further decreases in phytoplankton and...

  17. Occurrence and levels of glyphosate and AMPA in shallow lakes from the Pampean and Patagonian regions of Argentina.

    Science.gov (United States)

    Castro Berman, M; Marino, D J G; Quiroga, María Victoria; Zagarese, Horacio

    2018-06-01

    Glyphosate (N-(phosphonomethyl)glycine) is a broad-spectrum systemic herbicide used to kill weeds that compete with commercial crops. In Argentina, the use of glyphosate-based herbicides increased dramatically (up to ∼200,000 tons on 2012) since the introduction of glyphosate-resistant crops, such as transgenic soy and resistant corn, and the adoption of non-till practices in the 1990's. Sallow lakes within the Pampa region may be potentially impacted by continuous herbicide usage. We surveyed 52 shallow lakes from the Pampa region (Buenos Aires Province, Argentina) to assess the occurrence and concentrations of glyphosate and its main degradation product (AMPA). For comparison, we also sampled 24 shallow lakes from an area with no agricultural use of glyphosate (Northern Patagonia). Glyphosate and AMPA were analyzed by UPLC-MS/MS ESI (±) in lake water, suspended particulate matter (SPM), and sediment samples. Within the Pampa region, glyphosate residues were detected in >40% of samples. Glyphosate residues were detected more frequently in sediment and surface water than in SPM samples. The mean (maximum) concentrations of glyphosate were 2.11 (4.52) μg l -1 for surface water; 0.10 (0.13) μg l -1 for SPM and 10.47 (20.34) μg kg -1 for sediment samples, respectively. Whereas, mean (maximum) concentrations of AMPA were 0.84 and (0.90) μg l -1 for surface water; 0.07 (0.07) μg l -1 for SPM; and 22.53 (32.89) μg kg -1 for sediment samples. The herbicide was not detected in samples from the Patagonian region. To our knowledge, this is the first study reporting the occurrence and concentrations of the herbicide in freshwater lakes of Argentina. Copyright © 2018 Elsevier Ltd. All rights reserved.

  18. Hurricane Effects on a Shallow Lake Ecosystem and Its Response to a Controlled Manipulation of Water Level

    Directory of Open Access Journals (Sweden)

    Karl E. Havens

    2001-01-01

    Full Text Available In order to reverse the damage to aquatic plant communities caused by multiple years of high water levels in Lake Okeechobee, Florida (U.S., the Governing Board of the South Florida Water Management District (SFWMD authorized a "managed recession" to substantially lower the surface elevation of the lake in spring 2000. The operation was intended to achieve lower water levels for at least 8 weeks during the summer growing season, and was predicted to result in a large-scale recovery of submerged vascular plants. We treated this operation as a whole ecosystem experiment, and assessed ecological responses using data from an existing network of water quality and submerged plant monitoring sites. As a result of large-scale discharges of water from the lake, coupled with losses to evaporation and to water supply deliveries to agriculture and other regional users, the lake surface elevation receded by approximately 1 m between April and June. Water depths in shoreline areas that historically supported submerged plant communities declined from near 1.5 m to below 0.5 m. Low water levels persisted for the entire summer. Despite shallow depths, the initial response (in June 2000 of submerged plants was very limited and water remained highly turbid (due at first to abiotic seston and later to phytoplankton blooms. Turbidity decreased in July and the biomass of plants increased. However, submerged plant biomass did not exceed levels observed during summer 1999 (when water depths were greater until August. Furthermore, a vascular plant-dominated assemblage (Vallisnera, Potamogeton, and Hydrilla that occurred in 1999 was replaced with a community of nearly 98% Chara spp. (a macro-alga in 2000. Hence, the lake’s submerged plant community appeared to revert to an earlier successional stage despite what appeared to be better conditions for growth. To explain this unexpected response, we evaluated the impacts that Hurricane Irene may have had on the lake in the

  19. Impacts of climate warming on lake fish community structure and potential effects on ecosystem function

    NARCIS (Netherlands)

    Jeppesen, E.; Meerhoff, M.; Holmgren, K.; González-Bergonzoni, I.; Teixeira-de Mello, F.; Declerck, Steven A.J.; De Meester, L.; Søndergaard, M.; Lauridsen, T.; Bjerring, R.; Conde-Porcuna, J-M.; Mazzeo, N.; Iglesias, C.; Reizenstein, M.; Malmquist, H.J.; Liu, Z.; Balayla, D.; Lazzaro, X.

    2010-01-01

    Fish play a key role in the trophic dynamics of lakes, not least in shallow systems. With climate warming, complex changes in fish community structure may be expected owing to the direct and indirect effects of temperature, and indirect effects of eutrophication, water-level changes and salinisation

  20. Conversion of a moderately rewetted fen to a shallow lake - implications for net CO2 exchange

    Science.gov (United States)

    Koebsch, Franziska; Glatzel, Stephan; Hofmann, Joachim; Forbrich, Inke; Jurasinski, Gerald

    2013-04-01

    Extensive rewetting projects to re-establish the natural carbon (C) sequestration function of degraded peatlands are currently taking place in Europe and North-America. Year-round flooding provides a robust measure to prevent periods of drought that are associated with ongoing peat mineralization and to initiate the accumulation of new organic matter. Here, we present measurements of net carbon dioxide (CO2) exchange during the gradual conversion of a moderately rewetted fen to a shallow lake. When we started our measurements in 2009, mean growing season water level (MWGL) was 0 cm. In 2010 the site was flooded throughout the year with MWGL of 36 cm. Extraordinary strong rainfalls in July 2011 resulted in a further increase of MWGL to 56 cm. Measurements of net ecosystem exchange (NEE) were conducted during growing seasons (May-October) using the Eddy Covariance method. Information about vegetation vitality was deduced from the enhanced vegetation index (EVI) based on MODIS data. Ecosystem respiration (Reco) and gross ecosystem production (GEP) were high during vegetation period 2009 (1273.4 and -1572.1 g CO2-C m-2), but decreased by 61 and 46% respectively when the fen was flooded throughout 2010. Under water-logged conditions, heterotrophic respiration declines and gas exchange is limited. Moreover, flooding is a severe stress factor for plants and decreases autotrophic respiration and photosynthesis. However, in comparison to 2010, rates of Reco and GEP doubled during the beginning of growing season 2011, indicating plastic response strategies of wetland plants to flooding. Presumably, plants were not able to cope with the further increase of water levels to up to 120 cm in June/July 2011, resulting in another drop of GEP and Reco. The effects of plant vitality on GEP were confirmed by the remote sensed vegetation index. Throughout all three growing seasons, the fen was a distinct net CO2 sink (2009: -333.3±12.3, 2010: -294.1±8.4, -352.4±5.1 g CO2-C m-2

  1. Shallow groundwater quality and associated non-cancer health risk in agricultural areas (Poyang Lake basin, China).

    Science.gov (United States)

    Soldatova, Evgeniya; Sun, Zhanxue; Maier, Sofya; Drebot, Valeriia; Gao, Bai

    2018-03-24

    Owing to their accessibility, shallow groundwater is an essential source of drinking water in rural areas while usually being used without control by authorities. At the same time, this type of water resource is one of the most vulnerable to pollution, especially in regions with extensive agricultural activity. These factors increase the probability of adverse health effects in the population as a result of the consumption of shallow groundwater. In the present research, shallow groundwater quality in the agricultural areas of Poyang Lake basin was assessed according to world and national standards for drinking water quality. To evaluate non-cancer health risk from drinking groundwater, the hazard quotient from exposure to individual chemicals and hazard index from exposure to multiple chemicals were applied. It was found that, in shallow groundwater, the concentrations of 11 components (NO 3 - , NH 4 + , Fe, Mn, As, Al, rare NO 2 - , Se, Hg, Tl and Pb) exceed the limits referenced in the standards for drinking water. According to the health risk assessment, only five components (NO 3 - , Fe, As, rare NO 2 - and Mn) likely provoke non-cancer effects. The attempt to evaluate the spatial distribution of human health risk from exposure to multiple chemicals shows that the most vulnerable area is associated with territory characterised by low altitude where reducing or near-neutral conditions are formed (lower reaches of Xiushui and Ganjiang Rivers). The largest health risk is associated with the immune system and adverse dermal effects.

  2. The effects of season and sand mining activities on thermal regime and water quality in a large shallow tropical lake.

    Science.gov (United States)

    Sharip, Zati; Zaki, Ahmad Taqiyuddin Ahmad

    2014-08-01

    Thermal structure and water quality in a large and shallow lake in Malaysia were studied between January 2012 and June 2013 in order to understand variations in relation to water level fluctuations and in-stream mining activities. Environmental variables, namely temperature, turbidity, dissolved oxygen, pH, electrical conductivity, chlorophyll-A and transparency, were measured using a multi-parameter probe and a Secchi disk. Measurements of environmental variables were performed at 0.1 m intervals from the surface to the bottom of the lake during the dry and wet seasons. High water level and strong solar radiation increased temperature stratification. River discharges during the wet season, and unsustainable sand mining activities led to an increased turbidity exceeding 100 NTU, and reduced transparency, which changed the temperature variation and subsequently altered the water quality pattern.

  3. Evidence for a Drought-driven (pre-industrial) Regime Shift in an Australian Shallow Lake

    Science.gov (United States)

    Mills, K.; Gell, P.; Doan, P.; Kershaw, P.; McKenzie, M.; Lewis, T.; Tyler, J. J.

    2015-12-01

    We present a 750-year record of ecosystem response to long-term drought history from Lake Colac, Victoria. Using multiple lines of evidence, we test the sensitivity and resilience of Lake Colac to independently reconstructed drought history. The sedimentary archive shows that Lake Colac appears to be sensitive to periods of drought. Following drought conditions c. CE 1390, the lake ecosystem indicates signs of recovery. A succession of droughts in the early 1500s initiates a change in the diatom flora, with freshwater species declining and replaced by saline tolerant species, though there is little interpretable change in aquatic palynomorphs. An inferred drought, around CE 1720 appears to precede a major switch in the lake's ecosystem. The lake became increasingly turbid and saline and there is a distinct switch from a macrophyte-dominated system to an algal-dominated system. The arrival of Europeans in Victoria (CE1840) appears to have little effect on the lake's ecosystem, but the terrestrial vegetation indicates regionally established changes including declines in native trees, especially Casuarina, and arrival and expansion of exotic shade or plantation trees Pinus and Cupressus as well as native and introduced weeds. As European impact in the catchment increases, nutrients appear to play a role in the modification of the lake's ecosystem. A long-term drying trend from c. CE 1975 is evident, culminating in the Millennium Drought, which suggests unprecedented conditions in the ecological history of the Lake.

  4. Spatio-seasonal variability of chromophoric dissolved organic matter absorption and responses to photobleaching in a large shallow temperate lake

    Science.gov (United States)

    Encina Aulló-Maestro, María; Hunter, Peter; Spyrakos, Evangelos; Mercatoris, Pierre; Kovács, Attila; Horváth, Hajnalka; Preston, Tom; Présing, Mátyás; Torres Palenzuela, Jesús; Tyler, Andrew

    2017-03-01

    The development and validation of remote-sensing-based approaches for the retrieval of chromophoric dissolved organic matter (CDOM) concentrations requires a comprehensive understanding of the sources and magnitude of variability in the optical properties of dissolved material within lakes. In this study, spatial and seasonal variability in concentration and composition of CDOM and the origin of its variation was studied in Lake Balaton (Hungary), a large temperate shallow lake in central Europe. In addition, we investigated the effect of photobleaching on the optical properties of CDOM through in-lake incubation experiments. There was marked variability throughout the year in CDOM absorption in Lake Balaton (aCDOM(440) = 0. 06-9.01 m-1). The highest values were consistently observed at the mouth of the main inflow (Zala River), which drains humic-rich material from the adjoining Kis-Balaton wetland, but CDOM absorption decreased rapidly towards the east where it was consistently lower and less variable than in the westernmost lake basins. The spectral slope parameter for the interval of 350-500 nm (SCDOM(350-500)) was more variable with increasing distance from the inflow (observed range 0.0161-0.0181 nm-1 for the mouth of the main inflow and 0.0158-0.0300 nm-1 for waters closer to the outflow). However, spatial variation in SCDOM was more constant exhibiting a negative correlation with aCDOM(440). Dissolved organic carbon (DOC) was strongly positively correlated with aCDOM(440) and followed a similar seasonal trend but it demonstrated more variability than either aCDOM or SCDOM with distance through the system. Photobleaching resulting from a 7-day exposure to natural solar UV radiation resulted in a marked decrease in allochthonous CDOM absorption (7.04 to 3.36 m-1, 42 % decrease). Photodegradation also resulted in an increase in the spectral slope coefficient of dissolved material.

  5. Restoration of Shallow Lakes in Subtropical and Tropical China: Response of Nutrients and Water Clarity to Biomanipulation by Fish Removal and Submerged Plant Transplantation

    Directory of Open Access Journals (Sweden)

    Jinlei Yu

    2016-10-01

    Full Text Available Fish removal has been used to restore temperate lakes, and positive effects on ecological state and water clarity have frequently been recorded in many lakes. Recently, a supplementary measure, transplantation of submerged macrophytes after fish removal, has been applied to restore warm Chinese shallow lakes in order to compensate for the expected lack of increasing grazing control of phytoplankton after the biomanipulation. These measures have successfully shifted turbid warm lakes to a clear water state, but little is known about the responses to restoration of key physico-chemical variables. We analyzed the seasonal variation in nutrient concentrations in two subtropical and one tropical biomanipulated shallow Chinese lakes subjected to restoration. In all three lakes, a marked decline occurred in the concentrations of lake total nitrogen (TN, total phosphorus (TP, total suspended solids (TSS, and chlorophyll a (Chl a, while the transparency (SD:WD ratio, Secchi depth to water depth ratio increased. A clear water state was established, lasting so far for 7 to 23 months, and TN, TP, Chl a, and TSS levels in the three restored lakes decreased to, on average, 49%, 58%, 41%, and 18% of the level prior to restoration and/or the level in a reference lake, respectively, while the annual mean SD:WD ratio exhibited a 1.5–4 fold increase. In conclusion, lake restoration by transplantation of submerged macrophytes after fish removal had major positive effects on the physico-chemical variables in our study lakes. However, continuous control of omnivorous and herbivorous fish biomass is recommended as the fish typically present in warm, shallow lakes to some extent feed on submerged macrophytes, when available.

  6. Cyclic heliothermal behaviour of the shallow, hypersaline Lake Hayward, Western Australia

    Science.gov (United States)

    Turner, Jeffrey V.; Rosen, Michael R.; Coshell, Lee; Woodbury, Robert J.

    2018-05-01

    Lake Hayward is one of only about 30 hypersaline lakes worldwide that is meromictic and heliothermal and as such behaves as a natural salt gradient solar pond. Lake Hayward acts as a local groundwater sink, resulting in seasonally variable hypersaline lake water with total dissolved solids (TDS) in the upper layer (mixolimnion) ranging between 56 kg m-3 and 207 kg m-3 and the deeper layer (monimolimnion) from 153 kg m-3 to 211 kg m-3. This is up to six times the salinity of seawater and thus has the highest salinity of all eleven lakes in the Yalgorup National Park lake system. A program of continuously recorded water temperature profiles has shown that salinity stratification initiated by direct rainfall onto the lake's surface and local runoff into the lake results in the onset of heliothermal conditions within hours of rainfall onset. The lake alternates between being fully mixed and becoming thermally and chemically stratified several times during the annual cycle, with the longest extended periods of heliothermal behaviour lasting 23 and 22 weeks in the winters of 1992 and 1993 respectively. The objective was to quantify the heat budgets of the cyclical heliothermal behaviour of Lake Hayward. During the period of temperature profile logging, the maximum recorded temperature of the monimolimnion was 42.6 °C at which time the temperature of the mixolimnion was 29.4 °C. The heat budget of two closed heliothermal cycles initiated by two rainfall events of 50 mm and 52 mm in 1993 were analysed. The cycles prevailed for 11 and 20 days respectively and the heat budget showed net heat accumulations of 34.2 MJ m-3 and 15.4 MJ m-3, respectively. The corresponding efficiencies of lake heat gain to incident solar energy were 0.17 and 0.18 respectively. Typically, artificial salinity gradient solar ponds (SGSP) have a solar radiation capture efficiencies ranging from 0.10 up to 0.30. Results from Lake Hayward have implications for comparative biogeochemistry and its

  7. Cyclic heliothermal behaviour of the shallow, hypersaline Lake Hayward, Western Australia

    Science.gov (United States)

    Turner, Jeffrey V.; Rosen, Michael R.; Coshell, Lee; Woodbury, Robert J.

    2018-01-01

    Lake Hayward is one of only about 30 hypersaline lakes worldwide that is meromictic and heliothermal and as such behaves as a natural salt gradient solar pond. Lake Hayward acts as a local groundwater sink, resulting in seasonally variable hypersaline lake water with total dissolved solids (TDS) in the upper layer (mixolimnion) ranging between 56 kg m−3 and 207 kg m−3 and the deeper layer (monimolimnion) from 153 kg m−3 to 211 kg m−3. This is up to six times the salinity of seawater and thus has the highest salinity of all eleven lakes in the Yalgorup National Park lake system. A program of continuously recorded water temperature profiles has shown that salinity stratification initiated by direct rainfall onto the lake’s surface and local runoff into the lake results in the onset of heliothermal conditions within hours of rainfall onset.The lake alternates between being fully mixed and becoming thermally and chemically stratified several times during the annual cycle, with the longest extended periods of heliothermal behaviour lasting 23 and 22 weeks in the winters of 1992 and 1993 respectively. The objective was to quantify the heat budgets of the cyclical heliothermal behaviour of Lake Hayward.During the period of temperature profile logging, the maximum recorded temperature of the monimolimnion was 42.6 °C at which time the temperature of the mixolimnion was 29.4 °C.The heat budget of two closed heliothermal cycles initiated by two rainfall events of 50 mm and 52 mm in 1993 were analysed. The cycles prevailed for 11 and 20 days respectively and the heat budget showed net heat accumulations of 34.2 MJ m−3 and 15.4 MJ m−3, respectively. The corresponding efficiencies of lake heat gain to incident solar energy were 0.17 and 0.18 respectively. Typically, artificial salinity gradient solar ponds (SGSP) have a solar radiation capture efficiencies ranging from 0.10 up to 0.30. Results from Lake Hayward have

  8. Succession of Periphyton and Phytoplankton Assemblages in Years with Varying Amounts of Precipitation in a Shallow Urban Lake (Lake Jeziorak Mały, Poland

    Directory of Open Access Journals (Sweden)

    Zębek Elžbieta

    2014-08-01

    Full Text Available This study of periphyton assemblages (periphyton in separator pipes, epilithon and epiphyton and phytoplankton was carried out in Lake Jeziorak Maly in 1997-2003 and 2005. Since precipitation amounts varied in these years, changes in the abundance, biomass, taxonomic group structure, spe-cies diversity and dominant taxa of these assemblages were analyzed in relation to the physical and chemical water parameters. The periphyton in pipes had their highest abundance and biomass at the mean precipitation in the vegetative season and at maximum precipitations in winter 2000, and also in the 1997 vegetative season when there were high levels of electrolytic conductivity and orthophosphate and chloride concentrations. The assemblage was dominated by the diatoms Diatoma vulgaris which was resistant to washing and Navicula gregaria resistant to high amounts of organic matter. Similarly, maximum abundance and biomass of epilithon was found at the maximum precipitation level. However, in 2003 there was a low precipitation level which favoured habitation by epilithic filamentous chlorophytes, especially Ulothrix tenuissima. Meanwhile, epiphyton and phytoplankton thrived best in the high precipitation conditions and moderate chloride concentration in 2001. These assemblages were dominated by species typical for eutrophic waters, such as Gomphonema oliva-ceum and Planktolyngbya brevicellularis. Differences in the dynamics of periphyton assemblages and phytoplankton in the studied years indicate varying succession rates in these assemblages, especially in the separator pipes and on stones. These phenomena are considered to be related to the different environmental conditions engendered by variable amounts of precipitation.

  9. The influence of environmental variables on spatial and temporal phytoplankton dissimilarity in a large shallow subtropical lake (Lake Mangueira, southern Brazil

    Directory of Open Access Journals (Sweden)

    Luciane Oliveira Crossetti

    2014-06-01

    Full Text Available AIM: The uneven distribution of organisms in aquatic ecosystems is generally attributed to environmental heterogeneity in both space and time, reflecting the occurrence of appropriate environmental conditions and the availability of resources to biological communities. The aim of this study was to understand how the dissimilarity of the phytoplankton community in a large subtropical shallow lake is related to environmental dissimilarities. METHODS: Biotic and environmental data were gathered at 19 sites along the 90-km length of Lake Mangueira. Sampling was carried out quarterly during 2010 and 2011, totaling 152 sampling units. The relationship between phytoplankton dissimilarity and the dissimilarity of environmental variables was assessed by the BioEnv analysis. MAJOR RESULTS: There is a significant relationship between phytoplankton dissimilarity and environmental dissimilarity. The model that best explained the dissimilarity of phytoplankton among the sampling units included pH, turbidity and nitrate. CONCLUSIONS: The dissimilarity of phytoplankton was related to the dissimilarity, which were directly associated to the variability of conditions and resources in space and time in Lake Mangueira.

  10. Changes in food web structure and ecosystem functioning of a large, shallow Chinese lake during the 1950s, 1980s and 2000s

    DEFF Research Database (Denmark)

    Kong, Xiangzhen; He, Wei; Liu, Wenxiu

    2016-01-01

    that hydrological regulation may play a significant role in driving all of these changes in Lake Chaohu in addition to eutrophication and intensive fishery. Overall, we strongly advocate the identification of a threshold in abundance of zooplanktivorous fish, an integrated strategy for future ecological restoration......Food web structure dynamics and ecosystem functioning are strongly linked, and both are indispensable in evaluating ecosystem development in lakes under multiple anthropogenic stressors. However, model-based approaches concerning the changes in food web structure and ecosystem functioning...... validated by the stable isotope-determined trophic level (TL) for each functional group, which indicated an acceptable model performance. Over time, we observed a collapse of the food web toward a simplified structure and decreasing biodiversity and trophic interactions. The lake ecosystem was approaching...

  11. Patterns of microbial activity in the shallow bottom sediments of Lake ...

    African Journals Online (AJOL)

    FDA), was investigated in two sediment cores collected from Manzala Lake during November 2011. FDA hydrolysis positively correlated with total bacterial counts, bacterial biomass and chlorophyll a in both cores. The 10–20 cm subsurface layer ...

  12. Sources and behaviour of nitrogen compounds in the shallow groundwater of agricultural areas (Poyang Lake basin, China)

    Science.gov (United States)

    Soldatova, Evgeniya; Guseva, Natalia; Sun, Zhanxue; Bychinsky, Valeriy; Boeckx, Pascal; Gao, Bai

    2017-07-01

    Nitrogen contamination of natural water is a typical problem for various territories throughout the world. One of the regions exposed to nitrogen pollution is located in the Poyang Lake basin. As a result of agricultural activity and dense population, the shallow groundwater of this area is characterised by a high concentration of nitrogen compounds, primarily NO3-, with the concentration varying from 0.1 mg/L to 206 mg/L. Locally, high ammonium content occurs in the shallow groundwater with low reduction potential Eh ( 100 mV. To identify sources of nitrogen species and the factors that determine their behaviour, the dual stable isotope approach (δ15N and δ18О) and physical-chemical modelling were applied. Actual data were collected by sampling shallow groundwater from domestic water supply wells around the lake. The δ18О values from - 4.1‰ to 13.9‰ with an average value of 5.3 permille indicate a significant influence of nitrification on nitrogen balance. The enrichment of nitrate with the 15N isotope indicates that manure and domestic sewage are the principal sources of nitrogen compounds. Inorganic nitrogen speciation and thermodynamic calculations demonstrate the high stability of nitrate in the studied groundwater. Computer simulation and field observations indicate the reducing conditions formed under joint effects of anthropogenic factors and appropriate natural conditions, such as the low-level topography in which decreased water exchange rate can occur. The simulation also demonstrates the growth in pH of the groundwater as a consequence of fertilisation, which, in turn, conduced to the clay mineral formation at lower concentrations of aqueous clay-forming components than the ones under the natural conditions.

  13. RAPID NITRATE UPTAKE RATES AND LARGE SHORT-TERM STORAGE CAPACITIES MAY EXPLAIN WHY OPPORTUNISTIC GREEN MACROALGAE DOMINATE SHALLOW EUTROPHIC ESTUARIES1.

    Science.gov (United States)

    Kennison, Rachel L; Kamer, Krista; Fong, Peggy

    2011-06-01

    We quantified the effects of initial macroalgal tissue nitrogen (N) status (depleted and enriched) and varying pulses of nitrate (NO 3 - ) concentration on uptake and storage of nitrogen in Ulva intestinalis L. and Ulva expansa (Setch.) Setch. et N. L. Gardner using mesocosms modeling shallow coastal estuaries in Mediterranean climates. Uptake of NO 3 - (μmol · g dry weight [dwt] -1  · h -1 ) was measured as loss from the water after 1, 2, 4, 8, 12, and 24 h and storage as total tissue nitrogen (% dwt) and nitrate (ppm). Both species of algae exhibited a high affinity for NO 3 - across all N pulses and initial tissue contents. There was greater NO 3 - removal from the water for depleted than enriched algae across all time intervals. In the low-N-pulse treatment, U. intestinalis and U. expansa removed all measurable NO 3 - within 8 and 12 h, respectively, and in the medium and high treatments, removal was high and then decreased over time. Maximum mean uptake rates of nitrate were greater for U. expansa (∼300 μmol · g dwt -1  · h -1 ) than U. intestinalis (∼100 μmol · g dwt -1  · h -1 ); however, uptake rates were highly variable over time. Overall, U. expansa uptake rates were double those of U. intestinalis. Maximum tissue NO 3 - for U. expansa was >1,000 ppm, five times that of U. intestinalis, suggesting that U. expansa has a greater storage capacity in this cellular pool. These results showed that opportunistic green algae with differing tissue nutrient histories were able to efficiently remove nitrate from the water across a wide range of N pulses; thus, both are highly adapted to proliferate in estuarine environments with pulsed nutrient supplies. © 2011 Phycological Society of America.

  14. Bisphenol analogues in surface water and sediment from the shallow Chinese freshwater lakes: Occurrence, distribution, source apportionment, and ecological and human health risk.

    Science.gov (United States)

    Yan, Zhengyu; Liu, Yanhua; Yan, Kun; Wu, Shengmin; Han, Zhihua; Guo, Ruixin; Chen, Meihong; Yang, Qiulian; Zhang, Shenghu; Chen, Jianqiu

    2017-10-01

    Compared to Bisphenol A (BPA), current knowledge on the spatial distribution, potential sources and environmental risk assessment of other bisphenol analogues (BPs) remains limited. The occurrence, distribution and sources of seven BPs were investigated in the surface water and sediment from Taihu Lake and Luoma Lake, which are the Chinese shallow freshwater lakes. Because there are many industries and living areas around Taihu Lake, the total concentrations of ∑BPs were much higher than that in Luoma Lake, which is away from the industry-intensive areas. For the two lakes, BPA was still the dominant BPs in both surface water and sediment, followed by BPF and BPS. The spatial distribution and principal component analysis showed that BPs in Luoma Lake was relatively homogeneous and the potential sources were relatively simple than that in Taihu Lake. The spatial distribution of BPs in sediment of Taihu Lake indicated that ∑BPs positively correlated with the TOC content. For both Taihu Lake and Luoma Lake, the risk assessment at the sampling sites showed that no high risk in surface water and sediment (RQ t  < 1.0, and EEQ t  < 1.0 ng E 2 /L). Copyright © 2017 Elsevier Ltd. All rights reserved.

  15. Origin and hydrogeochemistry of a shallow flow-through lake on a Pleistocene piedmont, northern Spanish Meseta

    Directory of Open Access Journals (Sweden)

    Margarita Jambrina

    2013-06-01

    Full Text Available The Cristo lagoon, situated on Neogene deposits in the northern Spanish Meseta, occupies a shallow depression on a Pleistocene piedmont. The development of the lacustrine depression on the piedmont was favoured by the fault network, reinforced by substrateloss by weathering, probably during the late Quaternary. Even during the hot summer season, salinity is low, with concentrations of total dissolved solids (TDS being around 150 mg L–1. Only when the lagoon is almost dry do TDS concentrations exceed 500 mg L–1, sometimes rising as high as 1700 mg L–1. Whenthe lake level is high, lake chemistry is dominated by Na+, Ca2+, HCO3– and Cl–. During drier stages, there is a relative increase in Ca2+, Mg2+, Cl–, and SO42–, trending toward a calcium chloride-sulphate brine. Values of pH are above 9 during late spring and summer, resulting primarily from evaporative degassing favoured by the shallow depth of water, and secondarily from photosynthesis by the abundant submerged macrophytes. The infilling deposits, less than 0.5 m thick, are dark brown, massive, sandy muds consisting of quartz and clays (illite, kaolinite, smectite, all of which are allogenic in origin. The main source of dissolved sulphate was the oxidation of sulphides during weathering of lower Palaeozoic rocks in the catchment area. The 13C-depleted nature of dissolved inorganic carbon indicates an origin mostly by respiration and oxidation of organic matter. Geomorphology and hydrogeochemistry indicate a flow-through lake dominated essentially by groundwater flows. 

  16. Long-term seasonal nutrient limiting patterns at Meiliang Bay in a large, shallow and subtropical Lake Taihu, China

    Directory of Open Access Journals (Sweden)

    Rui Ye

    2015-04-01

    Full Text Available Lake Taihu has undergone severe eutrophication in the past three decades, and harmful cyanobacteria blooms occur nearly every year in Meiliang Bay at the north end of the lake. To elucidate the potential relationship between seasonal nutrient limitation and phytoplankton proliferation, a 20-year (1991-2012 time series of nutrient limitation in Meiliang Bay was analyzed for deviations between trophic state index (TSI parameters. Results showed that patterns of nutrient limitation in Meiliang Bay were distinctly seasonal, where phytoplankton growth was generally phosphorus (P-limited in winter and spring, but nitrogen (N-limited mainly occurred in summer and fall. This general pattern, however, shifted into N limitation across the four seasons during the mid-1990s because a rapid increase in industrialization led to a significant rise in the input of N and P from inflowing tributaries. The initial patterns were restored by environmental regulation in the end of 1990s, including the Zero Actions plan. Using routine monitoring data, a generalised additive model (GAM with time and deviations between trophic state indexes for nitrogen and phosphorus (TSIN-TSIP as explanatory variables was used to explore which nutrient was responsible for limitation of phytoplankton chlorophyll-a (Chl-a in different seasons. Surprisingly, the model revealed a weak N limitation (TSIN-TSIP = -10 corresponded to peak values of Chl-a in summer-autumn season, which is probably because the phytoplankton community is co-limited by N & P during the period. The shift of nutrition limitation during winter-spring would partially explain high values of Chl-a throughout 1996. This study suggests that seasonal patterns of nutrient limitation must be considered to develop effective management measures to control cyanobacterial blooms.

  17. Impacts of flamingos on saline lake margin and shallow lacustrine sediments in the Kenya Rift Valley

    Science.gov (United States)

    Scott, Jennifer J.; Renaut, Robin W.; Owen, R. Bernhart

    2012-11-01

    Studies of modern, Holocene, and Pleistocene sediments around saline to hypersaline, alkaline Lake Bogoria and Lake Magadi show that evidence of flamingo activity in marginal areas of these lakes is nearly ubiquitous. Flamingos produce discrete structures such as webbed footprints (~ 9 cm long, ~ 11 cm wide) and nest mounds (~ 30 cm wide, ~ 20 cm high), and they also extensively rework sediments in delta front, delta plain, and shoreline areas. Large (~ 0.5-2 cm in diameter), pinched, 'bubble pores' and ped-like mud clumps are formed by the trampling and churning of wet clay-rich sediments in these settings. Flamingo nest mounds, although superficially similar to some thrombolite mounds, are typically internally structureless, unless formed on pre-existing sediments that preserve internal structures. The flamingo mounds consist of a dense, packed oval-shaped core, a surrounding 'body' of packed sediment, and an external layer with a ped-like texture of clumped mud. The nests may contain open holes from roots or feather shafts incorporated into the nest, and (or) burrows produced once the nests are abandoned. In areas with high densities of flamingos, lake margin sediments may be preferentially compacted, particularly at breeding sites, and become resistant to subaerial erosion and the effects of transgressive ravinement on time scales ranging from seasons to tens of thousands of years. The relatively well-compacted nest mounds and associated sediments also contribute to the stability of delta distributary channels during regressive-transgressive cycles, and can lead to the minor channelization of unconfined flows where currents are diverted around nest mounds. Pleistocene exhumed surfaces of relatively well-indurated lake margin sediments at Lake Bogoria and Lake Magadi that are interpreted as combined regressive and transgressive surfaces (flooding surface/sequence boundary) preserve evidence of flamingo activities, and are overlain by younger, porous lacustrine

  18. A critical review of the development, current hotspots, and future directions of Lake Taihu research from the bibliometrics perspective.

    Science.gov (United States)

    Zhang, Yunlin; Yao, Xiaolong; Qin, Boqiang

    2016-07-01

    Lake Taihu, as the important drinking water source of the Yangtze River Delta urban agglomeration and the third largest freshwater lake in China, has experienced serious lake eutrophication and water quality deterioration in the past three decades. Growing scientific, political, and public attention has been given to the water quality of Lake Taihu. This study aimed to conduct a comparative quantitative and qualitative analysis of the development, current hotspots, and future directions of Lake Taihu research using a bibliometric analysis of eight well-studied lakes (Lake Taihu, Lake Baikal, Lake Biwa, Lake Erie, Lake Michigan, Lake Ontario, Lake Superior and Lake Victoria) around the world based on the Science Citation Index (SCI) database. A total of 1582 papers discussing Lake Taihu research were published in 322 journals in the past three decades. However, the first paper about Lake Taihu research was not found in the SCI database until 1989, and there were only zero, one, or two papers each year from 1989 to 1995. There had been rapid development in Lake Taihu research since 1996 and a sharp increase in papers since 2005. A keyword analysis showed that "sediment," "eutrophication", "Microcystis aeruginosa", "cyanobacterial blooms", and "remote sensing" were the most frequently used keywords of the study subject. Owing to its significant impact on aquatic ecosystems, a crucial emphasis has been placed on climate change recently. In addition, the future focuses of research directions, including (1) environmental effects of physical processes; (2) nutrient cycles and control and ecosystem responses; (3) cyanobacteria bloom monitoring, causes, forecast and management; (4) eutrophication and climate change interactions; and (5) ecosystem degradation mechanism and ecological practice of lake restoration, are presented based on the keyword analysis. Through multidisciplinary fields (physics, chemistry, and biology) cross and synthesis study of Lake Taihu, the

  19. Microplastic pollution in lakes and lake shoreline sediments - A case study on Lake Bolsena and Lake Chiusi (central Italy).

    Science.gov (United States)

    Fischer, Elke Kerstin; Paglialonga, Lisa; Czech, Elisa; Tamminga, Matthias

    2016-06-01

    Rivers and effluents have been identified as major pathways for microplastics of terrestrial sources. Moreover, lakes of different dimensions and even in remote locations contain microplastics in striking abundances. This study investigates concentrations of microplastic particles at two lakes in central Italy (Lake Bolsena, Lake Chiusi). A total number of six Manta Trawls have been carried out, two of them one day after heavy winds occurred on Lake Bolsena showing effects on particle distribution of fragments and fibers of varying size categories. Additionally, 36 sediment samples from lakeshores were analyzed for microplastic content. In the surface waters 2.68 to 3.36 particles/m(3) (Lake Chiusi) and 0.82 to 4.42 particles/m(3) (Lake Bolsena) were detected, respectively. Main differences between the lakes are attributed to lake characteristics such as surface and catchment area, depth and the presence of local wind patterns and tide range at Lake Bolsena. An event of heavy winds and moderate rainfall prior to one sampling led to an increase of concentrations at Lake Bolsena which is most probable related to lateral land-based and sewage effluent inputs. The abundances of microplastic particles in sediments vary from mean values of 112 (Lake Bolsena) to 234 particles/kg dry weight (Lake Chiusi). Lake Chiusi results reveal elevated fiber concentrations compared to those of Lake Bolsena what might be a result of higher organic content and a shift in grain size distribution towards the silt and clay fraction at the shallow and highly eutrophic Lake Chiusi. The distribution of particles along different beach levels revealed no significant differences. Copyright © 2016 Elsevier Ltd. All rights reserved.

  20. Assessing the role of bed sediments in the persistence of red mud pollution in a shallow lake (Kinghorn Loch, UK).

    Science.gov (United States)

    Olszewska, Justyna P; Heal, Kate V; Winfield, Ian J; Eades, Lorna J; Spears, Bryan M

    2017-10-15

    Red mud is a by-product of alumina production. Little is known about the long-term fate of red mud constituents in fresh waters or of the processes regulating recovery of fresh waters following pollution control. In 1983, red mud leachate was diverted away from Kinghorn Loch, UK, after many years of polluting this shallow and monomictic lake. We hypothesised that the redox-sensitive constituents of red mud leachate, phosphorus (P), arsenic (As) and vanadium (V), would persist in the Kinghorn Loch for many years following pollution control as a result of cycling between the lake bed sediment and the overlying water column. To test this hypothesis, we conducted a 12-month field campaign in Kinghorn Loch between May 2012 and April 2013 to quantify the seasonal cycling of P, As, and V in relation to environmental conditions (e.g., dissolved oxygen (DO) concentration, pH, redox chemistry and temperature) in the lake surface and bottom waters. To confirm the mechanisms for P, As and V release, a sediment core incubation experiment was conducted using lake sediment sampled in July 2012, in which DO concentrations were manipulated to create either oxic or anoxic conditions similar to the bed conditions found in the lake. The effects on P, As, and V concentrations and species in the water column were measured daily over an eight-day incubation period. Phosphate (PO 4 -P) and dissolved As concentrations were significantly higher in the bottom waters (75.9 ± 30.2 μg L -1 and 23.5 ± 1.83 μg L -1 , respectively) than in the surface waters (12.9 ± 1.50 μg L -1 and 14.1 ± 2.20 μg L -1 , respectively) in Kinghorn Loch. Sediment release of As and P under anoxic conditions was confirmed by the incubation experiment and by the significant negative correlations between DO and P and As concentrations in the bottom waters of the lake. In contrast, the highest dissolved V concentrations occurred in the bottom waters of Kinghorn Loch under oxic conditions (15.0

  1. The influence of nutrient loading, climate and water depth on nitrogen and phosphorus loss in shallow lakes: a pan-European mesocosm experiment.

    Czech Academy of Sciences Publication Activity Database

    Coppens, J.; Hejzlar, Josef; Šorf, Michal; Jeppesen, E.; Erdogan, S.; Scharfenberger, U.; Mahdy, A.; Noges, P.; Tuvikene, A.; Blaho, D.L.; Trigal, C.; Papastergiadou, E.; Stefanidis, K.; Olsen, S.; Beklioglu, M.

    2016-01-01

    Roč. 778, č. 1 (2016), s. 13-32 ISSN 0018-8158 EU Projects: European Commission(XE) 244121 - REFRESH Institutional support: RVO:60077344 Keywords : nutrient retention * nutrient budget * shallow lake * organic matter * temperature Subject RIV: DA - Hydrology ; Limnology Impact factor: 2.056, year: 2016

  2. Decade-long time delays in nutrient and plant species dynamics during eutrophication and re-oligotrophication of Lake Fure 1900–2015

    DEFF Research Database (Denmark)

    Sand-Jensen, Kaj; Bruun, Hans Henrik; Båstrup-Spohr, Lars

    2017-01-01

    Fure, Denmark, spanning the transformation from pristine environmental conditions in the early 1900s through a period (1920–1970) of eutrophication – from accelerating sewage input of phosphorus (P) – and subsequent re-oligotrophication after sewage cleaning (1970–2015). We examine time delays between...... sediment release. Fifty years of eutrophication led to a reduction in aquatic macrophyte richness from 36 species to 12. Species’ responses were closely related to their growth strategy and depth distribution. Deep-growing mosses, charophytes and short angiosperms disappeared, while tall angiosperms...... in species dominance takes longer than colonization by new species. Synthesis. Time delays of P concentrations, water clarity and macrophyte richness and composition were long and complex. Neglecting growth strategies of species makes application of extinction debt and colonization credit concepts dubious...

  3. Salinity shapes food webs in shallow lakes: implications for increasing aridity with climate change

    DEFF Research Database (Denmark)

    Vidal, Nicolas; Yu, Jinlei; Gutierrez, Maria Florencia

    2015-01-01

    on community and food web structure in 24 lakes along a wide salinity gradient, from freshwater (0.5 g L-1) to hypersaline lakes (115 g L-1), in a semiarid region in North West China. Fish, zooplankton and macroinvertebrate communities were sampled during July 2014 for determination of taxonomy and size......A reduction in runoff and higher evaporation rates are expected to occur towards 2050 in arid and semiarid regions of the world, resulting in a reduction of water level and salinization of inland waters. Besides the natural process of catchment erosion, human activities such as irrigation of crops...... may also increase salinization. Reduced biodiversity in freshwater systems is the most commonly reported effect of salinization, which may have implications for food web structure and likely for ecosystem functioning as well. The objective of the study was to analyze the effects of salinity...

  4. Atmospheric partitioning and the air-water exchange of polycyclic aromatic hydrocarbons in a large shallow Chinese lake (Lake Chaohu).

    Science.gov (United States)

    Qin, Ning; He, Wei; Kong, Xiang-Zhen; Liu, Wen-Xiu; He, Qi-Shuang; Yang, Bin; Ouyang, Hui-Ling; Wang, Qing-Mei; Xu, Fu-Liu

    2013-11-01

    The residual levels of polycyclic aromatic hydrocarbons (PAHs) in the atmosphere and in dissolved phase from Lake Chaohu were measured by (GC-MS). The composition and seasonal variation were investigated. The diffusive air-water exchange flux was estimated by a two-film model, and the uncertainty in the flux calculations and the sensitivity of the parameters were evaluated. The following results were obtained: (1) the average residual levels of all PAHs (PAH16) in the atmosphere from Lake Chaohu were 60.85±46.17 ng m(-3) in the gaseous phase and 14.32±23.82 ng m(-3) in the particulate phase. The dissolved PAH16 level was 173.46±132.89 ng L(-1). (2) The seasonal variation of average PAH16 contents ranged from 43.09±33.20 ng m(-3) (summer) to 137.47±41.69 ng m(-3) (winter) in gaseous phase, from 6.62±2.72 ng m(-3) (summer) to 56.13±22.99 ng m(-3) (winter) in particulate phase, and 142.68±74.68 ng L(-1) (winter) to 360.00±176.60 ng L(-1) (summer) in water samples. Obvious seasonal trends of PAH16 concentrations were found in the atmosphere and water. The values of PAH16 for both the atmosphere and the water were significantly correlated with temperature. (3) The monthly diffusive air-water exchange flux of total PAH16 ranged from -1.77×10(4) ng m(-2) d(-1) to 1.11×10(5) ng m(-2) d(-1), with an average value of 3.45×10(4) ng m(-2) d(-1). (4) The results of a Monte Carlo simulation showed that the monthly average PAH fluxes ranged from -3.4×10(3) ng m(-2) d(-1) to 1.6×10(4) ng m(-2) d(-1) throughout the year, and the uncertainties for individual PAHs were compared. (5) According to the sensitivity analysis, the concentrations of dissolved and gaseous phase PAHs were the two most important factors affecting the results of the flux calculations. Copyright © 2013 Elsevier Ltd. All rights reserved.

  5. Paleolimnological sedimentation of organic carbon, nitrogen, phosphorus, fossil pigments, pollen, and diatoms in a hypereutrophic, hardwater lake: a case history of eutrophication

    Energy Technology Data Exchange (ETDEWEB)

    Manny, B.A.; Wetzel, R.G.; Bailey, R.E.

    1977-01-01

    The sediment history of this productive, hardwater lake (Wintergreen Lake in southern Michigan) developed as five periods of increasing eutrophy, each strongly influenced by a hybrid basin morphometry. This morphometry led to higher productivity per unit area by macrophytic plants in littoral waters of the lake than by phytoplankton in pelagic waters. Climate and trophic conditions during each of the five periods between 14,000 and 0 B.P. are postulated.

  6. The synergetic effects of turbulence and turbidity on the zooplankton community structure in large, shallow Lake Taihu.

    Science.gov (United States)

    Zhou, Jian; Qin, Boqiang; Han, Xiaoxia

    2018-01-01

    Climate change is predicted to influence the heat budget of aquatic ecosystems and, in turn, affect the stability of the water column leading to increased turbulence coupled with enhanced turbidity. However, the synergetic effects of turbulence and turbidity on zooplankton community structure remain to be understood in large, shallow lakes. To determine the possible synergetic effects of these factors on zooplankton communities, a 15-day mesocosm experiment was carried out and tested under four turbulence and turbidity regimes namely control (ɛ = 0, 7.6 ± 4.2 NTU), low (ɛ = 6.01 × 10 -8  m 2  s -3 , 19.4 ± 8.6 NTU), medium (ɛ = 2.95 × 10 -5  m 2  s -3 , 55.2 ± 14.4 NTU), and high (ɛ = 2.39 × 10 -4  m 2  s -3 , 741.6 ± 105.2 NTU) conditions, which were comparable to the natural conditions in Lake Taihu. Results clearly showed the negative effects of turbulence and turbidity on zooplankton survival, which also differed among taxa. Specifically, increased turbulence and turbidity levels influenced the competition among zooplankton species, which resulted to the shift from being large body crustacean-dominated (copepods and cladocerans) to rotifer-dominated community after 3 days. The shift could be associated with the decrease in vulnerability of crustaceans in such environments. Our findings suggested that changes in the level of both turbidity and turbulence in natural aquatic systems would have significant repercussions on the zooplankton communities, which could contribute to the better understanding of community and food web dynamics in lake ecosystems exposed to natural mixing/disturbances.

  7. How well suited are maar lakes of Madagascar for palaeoenvironmental multi-proxy reconstructions? - First results from shallow seismic, sedimentological and hydrological investigations in Central and Northwest Madagascar.

    Science.gov (United States)

    Daut, Gerhard; Jasmin Krahn, Kim; Rabhobisoa, Jean-Jacques; Ornella Moanazafy, Sergénie; Haberzettl, Torsten; Kasper, Thomas; Mäusbacher, Roland; Schwalb, Antje

    2017-04-01

    Madagascar is well known for its unique flora and fauna which are frequently in the focus of scientific investigations. However, studies on environmental changes in Madagascar linked to Quaternary climatic and/or anthropogenic impact are scarce. The aim of this initial study is to evaluate the potential of maar lakes, situated in different climatic zones of Madagascar, for paleoenvironmental studies and to identify promising coring sites with continuous sediment sequences reaching far back in time. Therefore, in November 2016, a shallow seismic profiling campaign, combined with surface sediment, short gravity core (max. 1.8 m), water and plankton sampling was performed on three target sites. These were two deep maar lakes, i.e., Andraikiba (Central Madagascar, 50m waterdepth) as well as Amparahibe (46,5m waterdepth) and Andampy Ambatoloaka, a shallow (5m waterdepth during low tide) former maar lake now connected to the Ocean (both NW-Madagascar. Vertical water parameter measurements in Lake Amparahibe confirm anoxic bottom conditions, while dissolved oxygen values at the water surface are about 7.9 mg/L (103%). Temperature decreases with depth from 29.3 °C to 27.2 °C, and the lake is slightly alkaline with an electrical conductivity of around 245 µS/cm. Since Andampy Ambatoloaka is connected to the ocean, it shows slightly alkaline conditions as well, electrical conductivity is high ( 57.8 mS/cm) and dissolved oxygen and temperature values are relatively stable at about 8.2 mg/L (104%) and 28.1 °C, respectively. The shallow seismic survey shows an infill with layered sediments of >50 m thickness in Lake Andraikiba. In Lake Amparahibe natural gas in the sediment prevented deeper penetration, however the record shows 10 m of undisturbed, layered sediments in the uppermost part. Sediment cores obtained from both lakes consist of dark brownish to blackish, clayey to silty and partly laminated sediments. High values of magnetic susceptibilities (>1800*10-6 SI) and

  8. Lake depth rather than fish planktivory determines cladoceran community structure in Faroese lakes - evidence from contemporary data and sediments

    DEFF Research Database (Denmark)

    Amsinck, S.L.; Strzelczak, A.; Bjerring, R.

    2006-01-01

    development was inferred by cladoceran-based paleolimnological investigations of a 14C-dated sediment core covering the last ca 5700 years. 3. The 29 study lakes were overall shallow, small-sized, oligotrophic and dominated by brown trout (Salmo trutta). Cladoceran species richness was overall higher...... depth. A recent increase in inferred Zmax may, however, be an artefact induced by, for instance, eutrophication....

  9. Prevalence of Colacium vesiculosum (Colaciales: Euglenophyceae on planktonic crustaceans in a subtropical shallow lake of Argentina

    Directory of Open Access Journals (Sweden)

    Yolanda Zalocar

    2011-09-01

    Full Text Available Colacium vesiculosum (Euglenophyceae is an epibiont common on planktonic microcrustaceans of continental waters. The interaction between epibionts and substrate organisms is not very well known, particularly in subtropical environments of South America. In the present work, we analyzed the prevalence, density, biomass and attachment sites of C. vesiculosum on planktonic microcrustaceans from Paiva Lake, a subtropical lake of Argentina. With the aim to evaluate whether epibionts affect the filtering rates of Notodiaptomus spiniger, the dominant planktonic crustacean, we carried out bioassays using phytoplankton <53µm. Crustaceans were sampled using a PVC tube (1.2m long and 10cm in diameter, filtering 50L of water through a 53µm-mesh. Microcrustaceans were counted in Bogorov chambers under a stereoscopic microscope. The infested organisms were separated and observed with a photonic microscope to determine density and biovolume of epibionts, by analyzing their distribution on the exoskeleton. The prevalence of C. vesiculosum was higher in adult crustaceans than in their larvae and juveniles. The most infested group was that of calanoid copepods, related to their high density. The attachment sites on the exoskeleton were found to be the portions of the body which have a higher probability of encounter with epibionts during locomotion and feeding, i.e., antennae and thoracic legs in copepods, and thoracic legs and postabdomen in cladocerans. The similar values found in the filtering rate of infested and uninfested individuals of N. spiniger and the constant prevalence (<40% of epibiont algae, suggest that C. vesiculosum does not condition the life of planktonic crustaceans of Paiva Lake. Rev. Biol. Trop. 59 (3: 1295-1306. Epub 2011 September 01.

  10. Trends in eutrophication research and control

    Science.gov (United States)

    Rast, Walter; Thornton, Jeffrey A.

    1996-02-01

    Eutrophication is the natural ageing process of lakes. It is characterized by a geologically slow shift from in-lake biological production driven by allochthonous (external to the water body) loading of nutrients, to production driven by autochthonous (in-lake) processes. This shift typically is accompanied by changes in species and biotic community composition, as an aquatic ecosystem is ultimately transformed into a terrestrial biome. However, this typically slow process can be greatly accelerated by human intervention in the natural biogeochemical cycling of nutrients within a watershed; the resulting cultural eutrophication can create conditions inimical to the continued use of the water body for human-driven economic purposes. Excessive algal and rooted plant growth, degraded water quality, extensive deoxygenation of the bottom water layers and increased fish biomass accompanied by decreased harvest quality, are some features of this process.Following the Second World War, concern with cultural eutrophication achieved an intensity that spurred a significant research effort, culminating in the identification of phosphorus as the single most significant, and controllable, element involved in driving the eutrophication process. During the late 1960s and throughout the 1970s, much effort was devoted to reducing phosphorus in wastewater effluents, primarily in the developed countries of the temperate zone. These efforts generally resulted in the control of eutrophication in these countries, albeit with varying degrees of success. The present effort in the temperature zone, comprising mostly developed nations, has now shifted to the control of diffuse sources of a broader spectrum of contaminants that impact human water use.In the developing countries of the inter-tropical zone, however, rapidly expanding populations, a growing industrial economy and extensive urbanization have only recently reached an intensity at which cultural eutrophication can no longer be

  11. Geographical information systems as a tool in limnological studies An applied case study in a shallow .lake of a plain area, Buenos Aires province, Argentina

    International Nuclear Information System (INIS)

    Quiroz, Orlando; Romanelli, Asuncion; Martinez, Daniel

    2009-01-01

    The understanding of the hydrological functioning and the interaction among the different water bodies in an area is essential when a sustainable use of the hydric resources is considered. The aim of the present paper is to assess both hydrological-limnological methods and GIS as an integrated methodology applied to the study of shallow lakes, and the hydrological behavior of shallow wetlands in plain areas. La Salada is an areic permanent shallow lake with an area of 5,78 km 2 located near La Dulce town (SE of Buenos Aires Province, Argentina). In this paper we applied methods and tools of the Geographical information Systems in order to assess both, the evolution and state of the wetland. Topographic profiles, showing the relationship among the lake and the other aquatic systems, and also a multi temporal assessment of the morphometric parameters were performed by using a Digital Terrain Model of the area. A sample grid was designed to obtain bathymetric, hydrogeochemical and isotopic data. The chemical water composition is homogeneous in area and depth. changes in the conductivity values along depth, the isotopic contents and the Gibbs diagram showed that the evaporation is the main process controlling the water chemistry. Physical-chemical parameters established water quality and uses of the lake.

  12. Sulphate balance of lakes and shallow groundwater in the Vasavere buried valley, Northeast Estonia

    International Nuclear Information System (INIS)

    Erg, K.

    2003-01-01

    Groundwater is an important component of many water resource systems supplying water for domestic use, industry, and agriculture. In recent years the attention has been focused on groundwater contamination by mine water. Decline in mining activities and introduction of new technologies together with economic measures has improved the situation but much should be done during coming years. Oil shale mining brings about changes in the groundwater regime and chemical composition. The correlation between the natural (meteorological and hydrological) and technogenic (mining-technological, hydrogeological, hydrochemical) factors caused by the oil shale mining in the Vasavere valley during 1970-2000 has been studied. As a result of extensive drainage of mining shafts and water consumption, the groundwater table has noticeably lowered in the area and sulphate content in lakes and groundwater is especially high

  13. The tempo-spatial variations of phytoplankton diversities and their correlation with trophic state levels in a large eutrophic Chinese lake

    DEFF Research Database (Denmark)

    Yang, Bin; Jiang, Yu-Jiao; He, Wei

    2016-01-01

    status of the lake. The present study indicated that the Margalef index of all samples was as low as 0.799 ± 0.543 in summer (August 2011) and as high as 1.467 ± 0.653 in winter (February 2012). The Margalef index of the river samples had a high mean value and substantial variation compared with the lake...... occurred in the eastern lake, especially in the middle of the lake, in autumn and winter. The total trophic state index (TSI) in all samples exhibited a significant negative correlation with the Margalef (r = −0.726) and Peilou (r = −0.530) indices but a significant positive correlation with the Shannon...

  14. Investigation of Temperature Dynamics in Small and Shallow Reservoirs, Case Study: Lake Binaba, Upper East Region of Ghana

    Directory of Open Access Journals (Sweden)

    Ali Abbasi

    2016-03-01

    Full Text Available An unsteady fully three-dimensional model of Lake Binaba (a shallow small reservoir in semi-arid Upper East Region of Ghana has been developed to simulate its temperature dynamics. The model developed is built on the Reynolds Averaged Navier–Stokes (RANS equations, utilizing the Boussinesq approach. As the results of the model are significantly affected by the physical conditions on the boundaries, allocating appropriate boundary conditions, particularly over a water surface, is essential in simulating the lake’s thermal structure. The thermal effects of incoming short-wave radiation implemented as a heat source term in the temperature equation, while the heat fluxes at the free water surface, which depend on wind speed, air temperature, and atmospheric stability conditions are considered as temperature boundary condition. The model equations were solved using OpenFOAM CFD toolbox. As the flow is completely turbulent, which is affected by the complex boundary conditions, a new heat transfer solver and turbulence model were developed to investigate the spatial and temporal distribution of temperature in small and shallow inland water bodies using improved time-dependent boundary conditions. The computed temperature values were compared with four days of observed field data. Simulated and observed temperature profiles show reasonable agreement where the root mean square error (RMSE over the simulation period ranges from 0.11 to 0.44 °C in temporal temperature profiles with an average value of 0.33 °C. Results indicate that the model is able to simulate the flow variables and the temperature distribution in small inland water bodies with complex bathymetry.

  15. On the methane paradox: Transport from shallow water zones rather than in situ methanogenesis is the major source of CH4 in the open surface water of lakes

    Science.gov (United States)

    Encinas Fernández, Jorge; Peeters, Frank; Hofmann, Hilmar

    2016-10-01

    Estimates of global methane (CH4) emissions from lakes and the contributions of different pathways are currently under debate. In situ methanogenesis linked to algae growth was recently suggested to be the major source of CH4 fluxes from aquatic systems. However, based on our very large data set on CH4 distributions within lakes, we demonstrate here that methane-enriched water from shallow water zones is the most likely source of the basin-wide mean CH4 concentrations in the surface water of lakes. Consistently, the mean surface CH4 concentrations are significantly correlated with the ratio between the surface area of the shallow water zone and the entire lake, fA,s/t, but not with the total surface area. The categorization of CH4 fluxes according to fA,s/t may therefore improve global estimates of CH4 emissions from lakes. Furthermore, CH4 concentrations increase substantially with water temperature, indicating that seasonally resolved data are required to accurately estimate annual CH4 emissions.

  16. Prevalence of Colacium vesiculosum (Colaciales: Euglenophyceae on planktonic crustaceans in a subtropical shallow lake of Argentina

    Directory of Open Access Journals (Sweden)

    Yolanda Zalocar

    2011-09-01

    Full Text Available Colacium vesiculosum (Euglenophyceae is an epibiont common on planktonic microcrustaceans of continental waters. The interaction between epibionts and substrate organisms is not very well known, particularly in subtropical environments of South America. In the present work, we analyzed the prevalence, density, biomass and attachment sites of C. vesiculosum on planktonic microcrustaceans from Paiva Lake, a subtropical lake of Argentina. With the aim to evaluate whether epibionts affect the filtering rates of Notodiaptomus spiniger, the dominant planktonic crustacean, we carried out bioassays using phytoplankton Colacium vesiculosum Ehrenberg (Euglenophyceae es un epibionte común en microcrustáceos del plancton de aguas continentales. La interacción epibiontes y organismo substrato es poco conocida, particularmente en ambientes subtropicales de América del Sur. Se analiza la prevalencia, densidad, biomasa y sitios de adhesión de C. vesiculosum en microcrustáceos planctónicos de un lago subtropical de Argentina. Con el fin de evaluar si los epibiontes afectan la tasa de filtración de Notodiaptomus spiniger Brian, crustáceo dominante del zooplancton, se realizaron bioensayos utilizando el fitoplancton <53µm. Los crustáceos fueron muestreados con un tubo de PVC (1m de largo, 10cm de diámetro filtrándose 50L de agua a través de una red de 53µm de abertura de malla. El recuento de los microcrustáceos se realizó en cámaras de Bogorov bajo microscopio estereoscópico. Los organismos infectados fueron separados y observados al microscopio fotónico para determinaciones de densidad y biovolumen de los epibiontes, y su distribución en el exoesqueleto. La prevalencia de C. vesiculosum fue mayor en crustáceos adultos que en estadíos larvales y juveniles. El grupo más infestado fue el de los copépodos calanoideos en relación con su alta densidad. Los sitios de adhesión sobre el exoesqueleto fueron las regiones del cuerpo que durante la

  17. Differences in planktonic microbial communities associated with three types of macrophyte stands in a shallow lake.

    Science.gov (United States)

    Mentes, Anikó; Szabó, Attila; Somogyi, Boglárka; Vajna, Balázs; Tugyi, Nóra; Csitári, Bianka; Vörös, Lajos; Felföldi, Tamás

    2018-02-01

    Little is known about how various substances from living and decomposing aquatic macrophytes affect the horizontal patterns of planktonic bacterial communities. Study sites were located within Lake Kolon, which is a freshwater marsh and can be characterised by open-water sites and small ponds with different macrovegetation (Phragmites australis, Nymphea alba and Utricularia vulgaris). Our aim was to reveal the impact of these macrophytes on the composition of the planktonic microbial communities using comparative analysis of environmental parameters, microscopy and pyrosequencing data. Bacterial 16S rRNA gene sequences were dominated by members of phyla Proteobacteria (36%-72%), Bacteroidetes (12%-33%) and Actinobacteria (5%-26%), but in the anoxic sample the ratio of Chlorobi (54%) was also remarkable. In the phytoplankton community, Cryptomonas sp., Dinobryon divergens, Euglena acus and chrysoflagellates had the highest proportion. Despite the similarities in most of the measured environmental parameters, the inner ponds had different bacterial and algal communities, suggesting that the presence and quality of macrophytes directly and indirectly controlled the composition of microbial plankton. © FEMS 2017. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  18. Effects of natural banks of free-floating plants on zooplankton community in a shallow subtropical lake in Southern Brazil

    Directory of Open Access Journals (Sweden)

    Vanessa Gazulha

    2011-08-01

    Full Text Available The aim of this study was to test the effects of natural free-floating plants on zooplankton distribution in a shallow subtropical lake. First, the hypothesis that free-floating plants have an effect on physico-chemicals, leading to a decrease on nutrient availability and influencing the phytoplankton biomass and zooplankton community was tested. Second, the hypothesis that free-floating plants act as a refuge for zooplankton was tested. Three microhabitats were selected: free-floating plants, littoral area and open water. Results demonstrated that the effects of different microhabitats on phytoplankton biomass and physico-chemicals were not significant, indicating a weak influence of the plants. Zooplankton densities were higher in free-floating plants and littoral area, although the effect of microhabitats was weak for most of the predominant genera. The absence of free-floating plant effects on phytoplankton and physico-chemicals showed that it was not a factor influencing the microcrustacean distribution in the microhabitats. Low differences in densities of zooplankton among microhabitats and low abundance of large-bodied cladocerans led to reject the hypothesis that free-floating plants act as a refuge for zooplankton.

  19. The evolution of a mining lake - From acidity to natural neutralization

    Energy Technology Data Exchange (ETDEWEB)

    Sienkiewicz, Elwira, E-mail: esienkie@twarda.pan.pl; Gąsiorowski, Michał, E-mail: mgasior@twarda.pan.pl

    2016-07-01

    Along the border of Poland and Germany (central Europe), many of the post-mining lakes have formed “an anthropogenic lake district”. This study presents the evolution of a mining lake ecosystem (TR-33) based on subfossil phyto- and zooplankton, isotopic data (δ{sup 13}C, δ{sup 15}N), elemental analyses of organic carbon and nitrogen (C/N ratio and TOC) and sedimentological analyses. Recently, lake TR-33 became completely neutralized from acidification and an increase in eutrophication began a few years ago. However, the lake has never been neutralized by humans; only natural processes have influenced the present water quality. From the beginning of the existence of the lake (1920s) to the present, we can distinguish four stages of lake development: 1) very shallow reservoir without typical lake sediments but with a sand layer containing fine lignite particles and very poor diatom and cladoceran communities; 2) very acidic, deeper water body with increasing frequencies of phyto- and zooplankton; 3) transitional period (rebuilding communities of diatoms and Cladocera), meaning a deep lake with benthic and planktonic fauna and flora with wide ecological tolerances; and 4) a shift to circumneutral conditions with an essential increase in planktonic taxa that prefer more fertile waters (eutrophication). In the case of lake TR-33, this process of natural neutralization lasted approximately 23 years. - Highlights: • Originally acid water lake had poor phyto- and zooplankton populations. • Process of natural neutralization lasted approximately 23 years. • Presently, lake's ecosystem is similar to other shallow lakes in the region. • Changes in the lake are representative for other mine lakes.

  20. Biosedimentary and geochemical constraints on the precipitation of mineral crusts in shallow sulphate lakes

    Science.gov (United States)

    Cabestrero, Óscar; del Buey, Pablo; Sanz-Montero, M. Esther

    2018-04-01

    Seasonal desiccation of Mg2+-(Na+)-(Ca2+)-SO42--(Cl-) saline lakes in La Mancha (Central Spain) that host microbial mats led to the precipitation of hydrated Na-Mg sulphates and gypsum. Sulphates precipitated in the submerged conditions form extensive biolaminites, whilst in marginal areas they produce thin crusts. Sedimentological, mineralogical, petrographic and high resolution textural studies reveal that the crusts were formed within the benthic microbial mats that thrive at salinities ranging from 160 to 340 g·L-1. The minerals of the crusts are primary bloedite (Na2Mg(SO4)2·4H2O), epsomite (MgSO4·7H2O), gypsum (CaSO4·2H2O) and mirabilite (Na2SO4·10H2O), as well as secondary hexahydrite (MgSO4·6H2O) and thenardite (Na2SO4). Primary bloedite crystals, which form the framework of surficial and submerged crusts are seen to nucleate subaqueously and grow incorporatively within the matgrounds. Displacive and incorporative epsomite grows on previous bloedite crystals and also on the ground. Mirabilite is precipitated rapidly at the brine-air interface over bloedite and epsomite. Hexahydrite and thenardite are formed due to dehydration of epsomite and mirabilite, respectively. Hydrochemical modeling with PHREEQC indicated that evaporitic biolaminites are forming from brines undersaturated with respect to bloedite, epsomite and mirabilite, which suggests that the microorganisms contribute to the heterogeneous nucleation of the sulphates in the microbial mats. Unlike carbonates, the influence of microbes on the growth and morphology of complicated double salts such as bloedite has not been documented previously and provides a new perspective on the formation of hydrated sulphate minerals that are common on Earth as well as other planets.

  1. Is Recovery of Large-Bodied Zooplankton after Nutrient Loading Reduction Hampered by Climate Warming? A Long-Term Study of Shallow Hypertrophic Lake Søbygaard, Denmark

    Directory of Open Access Journals (Sweden)

    María Florencia Gutierrez

    2016-08-01

    Full Text Available Nutrient fluctuations and climate warming can synergistically affect trophic dynamics in lakes, resulting in enhanced symptoms of eutrophication, thereby potentially counteracting restoration measures. We performed a long-term study (23 years of zooplankton in Danish Lake Søbygaard, which is in recovery after nutrient loading reduction, but now faces the effects of climate warming. We hypothesized that the recovery of large-bodied zooplankton after nutrient loading reduction would be hampered by climate warming through indirect effects on fish size structure. We found a shift in macrozooplankton from initial dominance of Daphnia spp. towards Bosmina spp. as well as a decline in the body size of copepods and an increase in the abundance of nauplii. These changes coincided with the increase in small sized fish as a result of rising water temperature. Despite a reduction in body size, the total biomass of cladocerans increased coinciding with a diminished fish catch per unit effort (CPUE, and likely then an overall reduction in the predation on zooplankton. A cascading effect to phytoplankton was evidenced by enhanced zooplankton:phytoplankton and cladoceran:phytoplankton ratios and a decrease in Chl-a:TP and Chl-a:TN ratios. Our results indicate that climate warming, through changes in the size structure of fish community, has major effects on zooplankton size structure. In Lake Søbygaard, the decline in zooplankton size did not prevent, but modulated, the positive cascading effect on phytoplankton through an expected diminished fish CPUE related to nutrient loading reduction.

  2. Contaminant Monitoring Strategy for Henrys Lake, Idaho

    Energy Technology Data Exchange (ETDEWEB)

    John S. Irving; R. P. Breckenridge

    1992-12-01

    Henrys Lake, located in southeastern Idaho, is a large, shallow lake (6,600 acres, {approx} 17.1 feet maximum depth) located at 6,472 feet elevation in Fremont Co., Idaho at the headwaters of the Henrys Fork of the Snake River. The upper watershed is comprised of high mountains of the Targhee National Forest and the lakeshore is surrounded by extensive flats and wetlands, which are mostly privately owned. The lake has been dammed since 1922, and the upper 12 feet of the lake waters are allocated for downriver use. Henrys Lake is a naturally productive lake supporting a nationally recognized ''Blue Ribbon'' trout fishery. There is concern that increasing housing development and cattle grazing may accelerate eutrophication and result in winter and early spring fish kills. There has not been a recent thorough assessment of lake water quality. However, the Department of Environmental Quality (DEQ) is currently conducting a study of water quality on Henrys Lake and tributary streams. Septic systems and lawn runoff from housing developments on the north, west, and southwest shores could potentially contribute to the nutrient enrichment of the lake. Many houses are on steep hillsides where runoff from lawns, driveways, etc. drain into wetland flats along the lake or directly into the lake. In addition, seepage from septic systems (drainfields) drain directly into the wetlands enter groundwater areas that seep into the lake. Cattle grazing along the lake margin, riparian areas, and uplands is likely accelerating erosion and nutrient enrichment. Also, cattle grazing along riparian areas likely adds to nutrient enrichment of the lake through subsurface flow and direct runoff. Stream bank and lakeshore erosion may also accelerate eutrophication by increasing the sedimentation of the lake. Approximately nine streams feed the lake (see map), but flows are often severely reduced or completely eliminated due to irrigation diversion. In addition, subsurface

  3. Palaeolimnological evidence of vulnerability of Lake Neusiedl (Austria) toward climate related changes since the last "vanished-lake" stage.

    Science.gov (United States)

    Tolotti, Monica; Milan, Manuela; Boscaini, Adriano; Soja, Gerhard; Herzig, Alois

    2013-04-01

    The palaeolimnological reconstruction of secular evolution of Euroepan Lakes with key socio-economical relevance respect to large (climate change) and local scale (land use, tourism) environmental changes, represents one of the objectives of the project EuLakes (European Lakes Under Environmental Stressors, Supporting lake governance to mitigate the impact of climate change, Reg. N. 2CE243P3), launched in 2010 within the Central European Inititiative. The project consortium comprises lakes of different morphology and prevalent human uses, including the meso-eutrophic Lake Neusiedl, the largest Austrian lake (total area 315 km2), and the westernmost shallow (mean depth 1.2 m) steppe lake of the Euro-Asiatic continent. The volume of Lake Neusiedl can potentially change over the years, in relation with changing balance between atmospheric precipitation and lake water evapotranspiration. Changing water budget, together with high lake salinity and turbidity, have important implications over the lake ecosystem. This contribution illustrates results of the multi-proxi palaeolimnological reconstruction of ecologial changes occurred in Lake Neusiedl during the last ca. 140 years, i.e. since the end of the last "vanished-lake" stage (1865-1871). Geochemical and biological proxies anticipate the increase in lake productivity of ca. 10 years (1950s) respect to what reported in the literature. Diatom species composition indicate a biological lake recovery in the late 1980s, and suggest a second increment in lake productivity since the late 1990s, possibly in relation with the progressive increase in the nitrogen input from agriculture. Abundance of diatoms typical of brackish waters indicated no significant long-term change in lake salinity, while variations in species toleranting dessiccation confirm the vulnerability of Lake Neusiedl toward climate-driven changes in the lake water balance. This fragility is aggravated by the the semi-arid climate conditions of the catchemnt

  4. Assessment of biological effects of pollutants in a hyper eutrophic tropical water body, Lake Beira, Sri Lanka using multiple biomarker responses of resident fish, Nile tilapia (Oreochromis niloticus).

    Science.gov (United States)

    Pathiratne, Asoka; Pathiratne, K A S; De Seram, P K C

    2010-08-01

    Biomarkers measured at the molecular and cellular level in fish have been proposed as sensitive "early warning" tools for biological effect measurements in environmental quality assessments. Lake Beira is a hypertrophic urban water body with a complex mixture of pollutants including polycyclic aromatic hydrocarbons (PAHs) and Microcystins. In this study, a suite of biomarker responses viz. biliary fluorescent aromatic compounds (FACs), hepatic ethoxyresorufin O-deethylase (EROD) and glutathione S-transferase (GST), brain and muscle cholinesterases (ChE), serum sorbitol dehydrogenase (SDH), and liver histology of Oreochromis niloticus, the dominant fish inhabiting this tropical Lake were evaluated to assess the pollution exposure and biological effects. Some fish sampled in the dry periods demonstrated prominent structural abnormalities in the liver and concomitant increase in serum SDH and reduction in hepatic GST activities in comparison to the control fish and the fish sampled in the rainy periods. The resident fish with apparently normal liver demonstrated induction of hepatic EROD and GST activities and increase in biliary FACs irrespective of the sampling period indicating bioavailability of PAHs. Muscle ChE activities of the resident fish were depressed significantly indicating exposure to anticholinesterase substances. The results revealed that fish populations residing in this Lake is under threat due to the pollution stress. Hepatic abnormalities in the fish may be mainly associated with the pollution stress due to recurrent exposure to PAHs and toxigenic Microcystis blooms in the Lake.

  5. A long-term study on crustacean plankton of a shallow tropical lake: the role of invertebrate predation

    Directory of Open Access Journals (Sweden)

    Marlene S. Arcifa

    2015-06-01

    Full Text Available The primary factor that governs the size and species composition of zooplankton is still a controversial issue and temperature is considered the main factor responsible for latitudinal differences. In waters with a narrow temperature range, such as in the tropics, predation may be a more important factor. Nearly three decades of intermittent studies of the crustacean plankton in a shallow tropical lake revealed that the main event that led to their restructuring was the appearance of a second predator, the water mite Krendowskia sp. The new predator and larvae of the dipteran Chaoborus brasiliensis Theobald exerted a combined, although asymmetrical effect on microcrustaceans. The period when the mite was detected was followed by the restructuring of the crustacean plankton community. Predation by these two invertebrates emerged as the factor responsible for community changes, involving an increased contribution of copepods and decreases in the relative abundance of smaller cladoceran species. In the short term, the mite caused a decrease in species richness and the annual mean instantaneous composition of cladocerans, a predominance of large-sized species (Daphnia ambigua Scourfield and Daphnia gessneri Herbst and the virtual disappearance of small species (e.g., Bosmina tubicen Brehm. The long-term impact resulted in increased species richness and the dominance of large and medium-sized cladocerans, such as D. gessneri and Ceriodaphnia richardi Sars. The larger body size of three cladocerans, the two Daphnia species and B. tubicen, in the long term, may be a response to the dominant predator, Chaoborus. The seasonal variation in the predator abundance, mainly Chaoborus larvae, allowed the prey to recover during the cool season. The copepods Tropocyclops prasinus meridionalis (Fischer and Thermocyclops decipiens Kiefer were less affected by predation than the cladocerans; their contribution to the crustacean plankton increased 12-28% after the

  6. MODIS observations of cyanobacterial risks in a eutrophic lake: Implications for long-term safety evaluation in drinking-water source.

    Science.gov (United States)

    Duan, Hongtao; Tao, Min; Loiselle, Steven Arthur; Zhao, Wei; Cao, Zhigang; Ma, Ronghua; Tang, Xiaoxian

    2017-10-01

    The occurrence and related risks from cyanobacterial blooms have increased world-wide over the past 40 years. Information on the abundance and distribution of cyanobacteria is fundamental to support risk assessment and management activities. In the present study, an approach based on Empirical Orthogonal Function (EOF) analysis was used to estimate the concentrations of chlorophyll a (Chla) and the cyanobacterial biomarker pigment phycocyanin (PC) using data from the MODerate resolution Imaging Spectroradiometer (MODIS) in Lake Chaohu (China's fifth largest freshwater lake). The approach was developed and tested using fourteen years (2000-2014) of MODIS images, which showed significant spatial and temporal variability of the PC:Chla ratio, an indicator of cyanobacterial dominance. The results had unbiased RMS uncertainties of MODIS Chla and PC products were then used for cyanobacterial risk mapping with a decision tree classification model. The resulting Water Quality Decision Matrix (WQDM) was designed to assist authorities in the identification of possible intake areas, as well as specific months when higher frequency monitoring and more intense water treatment would be required if the location of the present intake area remained the same. Remote sensing cyanobacterial risk mapping provides a new tool for reservoir and lake management programs. Copyright © 2017 Elsevier Ltd. All rights reserved.

  7. Quaternary Landforms and Basin Morphology Control the Natural Eutrophy of Boreal Lakes and Their Sensitivity to Anthropogenic Forcing

    Directory of Open Access Journals (Sweden)

    Mira Tammelin

    2018-05-01

    Full Text Available Both natural and anthropogenic changes in boreal lakes have been studied utilizing paleolimnological methods, but the spatial variation in the natural conditions of lakes and its connection to geological factors has drawn less attention. Our aims were to examine the spatial distribution of naturally eutrophic lakes on the previously glaciated terrain of central-eastern Finland and the relationship between pre-human disturbance water quality and geological factors related to the basins and their catchments. Furthermore, we studied the pre- to post-human disturbance changes in the diatom assemblages and water quality of 48 lakes (51 sampling sites across the pre-disturbance phosphorus gradient by using the top-bottom sampling approach and multivariate statistics. According to our results, naturally eutrophic boreal lakes are more common than previously thought, occurring on fine-grained and organic Quaternary landforms, including fine-grained till. Our study emphasizes the importance of the previously overlooked matter of till grain-size variation as a driver behind the spatial variation in the natural trophic states of boreal lakes. The location of a lake in the hydrologic landscape and basin morphology appear to be important factors as well. Shallow, naturally eutrophic lakes with short water residence times and high catchment area to lake area and volume ratios have been particularly sensitive to anthropogenic forcing. Our results indicate that cultural eutrophication is not the only water protection challenge for the relatively remote and dilute boreal lakes, but salinization and alkalinization are also serious threats that should be taken into account. Therefore, it is crucial to consider the notable variation in the natural conditions of boreal lakes in addition to mitigating the effects of anthropogenic forcing, such as nutrient loading, catchment erosion, salt pollution, and climate change, in order to achieve efficient water protection.

  8. Effects of water temperature on summer periphyton biomass in shallow lakes: a pan-European mesocosm experiment

    Czech Academy of Sciences Publication Activity Database

    Mahdy, A.; Hilt, S.; Filiz, N.; Beklioglu, M.; Hejzlar, Josef; Özkundakci, D.; Papastergiadou, E.; Scharfenberger, U.; Šorf, Michal; Stefanidis, K.; Tuvikene, L.; Zingel, P.; Sondergaard, M.; Jeppesen, E.; Adrian, R.

    2015-01-01

    Roč. 77, č. 3 (2015), s. 499-510 ISSN 1015-1621 R&D Projects: GA MŠk(CZ) 7E11059 EU Projects: European Commission(XE) 244121 Program:FP7 Institutional support: RVO:60077344 Keywords : climate change * eutrophication * epiphyton * grazing * top-down control Subject RIV: DA - Hydrology ; Limnology Impact factor: 2.398, year: 2015

  9. How physiological and physical processes contribute to the phenology of cyanobacterial blooms in large shallow lakes: A new Euler-Lagrangian coupled model.

    Science.gov (United States)

    Feng, Tao; Wang, Chao; Wang, Peifang; Qian, Jin; Wang, Xun

    2018-09-01

    Cyanobacterial blooms have emerged as one of the most severe ecological problems affecting large and shallow freshwater lakes. To improve our understanding of the factors that influence, and could be used to predict, surface blooms, this study developed a novel Euler-Lagrangian coupled approach combining the Eulerian model with agent-based modelling (ABM). The approach was subsequently verified based on monitoring datasets and MODIS data in a large shallow lake (Lake Taihu, China). The Eulerian model solves the Eulerian variables and physiological parameters, whereas ABM generates the complete life cycle and transport processes of cyanobacterial colonies. This model ensemble performed well in fitting historical data and predicting the dynamics of cyanobacterial biomass, bloom distribution, and area. Based on the calculated physical and physiological characteristics of surface blooms, principal component analysis (PCA) captured the major processes influencing surface bloom formation at different stages (two bloom clusters). Early bloom outbreaks were influenced by physical processes (horizontal transport and vertical turbulence-induced mixing), whereas buoyancy-controlling strategies were essential for mature bloom outbreaks. Canonical correlation analysis (CCA) revealed the combined actions of multiple environment variables on different bloom clusters. The effects of buoyancy-controlling strategies (ISP), vertical turbulence-induced mixing velocity of colony (VMT) and horizontal drift velocity of colony (HDT) were quantitatively compared using scenario simulations in the coupled model. VMT accounted for 52.9% of bloom formations and maintained blooms over long periods, thus demonstrating the importance of wind-induced turbulence in shallow lakes. In comparison, HDT and buoyancy controlling strategies influenced blooms at different stages. In conclusion, the approach developed here presents a promising tool for understanding the processes of onshore/offshore algal

  10. Fast phosphorus loss by sediment resuspension in a re-established shallow lake on former agricultural fields

    DEFF Research Database (Denmark)

    Kragh, Theis; Sand-Jensen, Kaj; Petersen, Kathrine

    2017-01-01

    Lake restoration on fertilized agricultural fields can lead to extensive nutrient release from flooded soils which can maintain a poor ecological quality in the new lake. The period with high sediment release is poorly understood due to few detailed lake restorations studies. We conducted such a ...

  11. Fast phosphorus loss by sediment resuspension in a re-established shallow lake on former agricultural fields

    DEFF Research Database (Denmark)

    Kragh, Theis; Sand-Jensen, Kaj; Petersen, Kathrine

    2017-01-01

    Lake restoration on fertilized agricultural fields can lead to extensive nutrient release from flooded soils which can maintain a poor ecological quality in the new lake. The period with high sediment release is poorly understood due to few detailed lake restorations studies. We conducted...

  12. Variability in methane emissions from West Siberia's shallow boreal lakes on a regional scale and its environmental controls

    Directory of Open Access Journals (Sweden)

    A. F. Sabrekov

    2017-08-01

    Full Text Available Small lakes represent an important source of atmospheric CH4 from northern wetlands. However, spatiotemporal variations in flux magnitudes and the lack of knowledge about their main environmental controls contribute large uncertainty into the global CH4 budget. In this study, we measured methane fluxes from small lakes using chambers and bubble traps. Field investigations were carried out in July–August 2014 within the West Siberian middle and southern taiga zones. The average and median of measured methane chamber fluxes were 0.32 and 0.30 mgCH4 m−2 h−1 for middle taiga lakes and 8.6 and 4.1 mgCH4 m−2 h−1 for southern taiga lakes, respectively. Pronounced flux variability was found during measurements on individual lakes, between individual lakes and between zones. To analyze these differences and the influences of environmental controls, we developed a new dynamic process-based model. It shows good performance with emission rates from the southern taiga lakes and poor performance for individual lakes in the middle taiga region. The model shows that, in addition to well-known controls such as temperature, pH and lake depth, there are significant variations in the maximal methane production potential between these climatic zones. In addition, the model shows that variations in gas-filled pore space in lake sediments are capable of controlling the total methane emissions from individual lakes. The CH4 emissions exhibited distinct zonal differences not only in absolute values but also in their probability density functions: the middle taiga lake fluxes were best described by a lognormal distribution while the southern taiga lakes followed a power-law distribution. The latter suggests applicability of self-organized criticality theory for methane emissions from the southern taiga zone, which could help to explain the strong variability within individual lakes.

  13. Heat-Wave Effects on Oxygen, Nutrients, and Phytoplankton Can Alter Global Warming Potential of Gases Emitted from a Small Shallow Lake.

    Science.gov (United States)

    Bartosiewicz, Maciej; Laurion, Isabelle; Clayer, François; Maranger, Roxane

    2016-06-21

    Increasing air temperatures may result in stronger lake stratification, potentially altering nutrient and biogenic gas cycling. We assessed the impact of climate forcing by comparing the influence of stratification on oxygen, nutrients, and global-warming potential (GWP) of greenhouse gases (the sum of CH4, CO2, and N2O in CO2 equivalents) emitted from a shallow productive lake during an average versus a heat-wave year. Strong stratification during the heat wave was accompanied by an algal bloom and chemically enhanced carbon uptake. Solar energy trapped at the surface created a colder, isolated hypolimnion, resulting in lower ebullition and overall lower GWP during the hotter-than-average year. Furthermore, the dominant CH4 emission pathway shifted from ebullition to diffusion, with CH4 being produced at surprisingly high rates from sediments (1.2-4.1 mmol m(-2) d(-1)). Accumulated gases trapped in the hypolimnion during the heat wave resulted in a peak efflux to the atmosphere during fall overturn when 70% of total emissions were released, with littoral zones acting as a hot spot. The impact of climate warming on the GWP of shallow lakes is a more complex interplay of phytoplankton dynamics, emission pathways, thermal structure, and chemical conditions, as well as seasonal and spatial variability, than previously reported.

  14. Invasive Macrophytes Control the Spatial and Temporal Patterns of Temperature and Dissolved Oxygen in a Shallow Lake: A Proposed Feedback Mechanism of Macrophyte Loss

    Directory of Open Access Journals (Sweden)

    Maria P. Vilas

    2017-12-01

    Full Text Available Submerged macrophytes can have a profound effect on shallow lake ecosystems through their ability to modify the thermal structure and dissolved oxygen levels within the lake. Invasive macrophytes, in particular, can grow rapidly and induce thermal gradients in lakes that may substantially change the ecosystem structure and challenge the survival of aquatic organisms. We performed fine-scale measurements and 3D numerical modeling at high spatiotemporal resolution to assess the effect of the seasonal growth of Potamogeton crispus L. on the spatial and temporal dynamics of temperature and dissolved oxygen in a shallow urban lake (Lake Monger, Perth, WA, Australia. Daytime stratification developed during the growing season and was clearly observed throughout the macrophyte bed. At all times measured, stratification was stronger at the center of the macrophyte bed compared to the bed edges. By fitting a logistic growth curve to changes in plant height over time (r2 = 0.98, and comparing this curve to temperature data at the center of the macrophyte bed, we found that stratification began once the macrophytes occupied at least 50% of the water depth. This conclusion was strongly supported by a 3D hydrodynamic model fitted to weekly temperature profiles measured at four time periods throughout the growing season (r2 > 0.78 at all times. As the macrophyte height increased and stratification developed, dissolved oxygen concentration profiles changed from vertically homogeneous oxic conditions during both the day and night to expression of night-time anoxic conditions close to the sediments. Spatially interpolated maps of dissolved oxygen and 3D numerical modeling results indicated that the plants also reduced horizontal exchange with surrounding unvegetated areas, preventing flushing of low dissolved oxygen water out of the center of the bed. Simultaneously, aerial imagery showed central dieback occurring toward the end of the growing season. Thus, we

  15. Invasive Macrophytes Control the Spatial and Temporal Patterns of Temperature and Dissolved Oxygen in a Shallow Lake: A Proposed Feedback Mechanism of Macrophyte Loss.

    Science.gov (United States)

    Vilas, Maria P; Marti, Clelia L; Adams, Matthew P; Oldham, Carolyn E; Hipsey, Matthew R

    2017-01-01

    Submerged macrophytes can have a profound effect on shallow lake ecosystems through their ability to modify the thermal structure and dissolved oxygen levels within the lake. Invasive macrophytes, in particular, can grow rapidly and induce thermal gradients in lakes that may substantially change the ecosystem structure and challenge the survival of aquatic organisms. We performed fine-scale measurements and 3D numerical modeling at high spatiotemporal resolution to assess the effect of the seasonal growth of Potamogeton crispus L. on the spatial and temporal dynamics of temperature and dissolved oxygen in a shallow urban lake (Lake Monger, Perth, WA, Australia). Daytime stratification developed during the growing season and was clearly observed throughout the macrophyte bed. At all times measured, stratification was stronger at the center of the macrophyte bed compared to the bed edges. By fitting a logistic growth curve to changes in plant height over time ( r 2 = 0.98), and comparing this curve to temperature data at the center of the macrophyte bed, we found that stratification began once the macrophytes occupied at least 50% of the water depth. This conclusion was strongly supported by a 3D hydrodynamic model fitted to weekly temperature profiles measured at four time periods throughout the growing season ( r 2 > 0.78 at all times). As the macrophyte height increased and stratification developed, dissolved oxygen concentration profiles changed from vertically homogeneous oxic conditions during both the day and night to expression of night-time anoxic conditions close to the sediments. Spatially interpolated maps of dissolved oxygen and 3D numerical modeling results indicated that the plants also reduced horizontal exchange with surrounding unvegetated areas, preventing flushing of low dissolved oxygen water out of the center of the bed. Simultaneously, aerial imagery showed central dieback occurring toward the end of the growing season. Thus, we hypothesized

  16. Hydrologic and Water-Quality Responses in Shallow Ground Water Receiving Stormwater Runoff and Potential Transport of Contaminants to Lake Tahoe, California and Nevada, 2005-07

    Science.gov (United States)

    Green, Jena M.; Thodal, Carl E.; Welborn, Toby L.

    2008-01-01

    Clarity of Lake Tahoe, California and Nevada has been decreasing due to inflows of sediment and nutrients associated with stormwater runoff. Detention basins are considered effective best management practices for mitigation of suspended sediment and nutrients associated with runoff, but effects of infiltrated stormwater on shallow ground water are not known. This report documents 2005-07 hydrogeologic conditions in a shallow aquifer and associated interactions between a stormwater-control system with nearby Lake Tahoe. Selected chemical qualities of stormwater, bottom sediment from a stormwater detention basin, ground water, and nearshore lake and interstitial water are characterized and coupled with results of a three-dimensional, finite-difference, mathematical model to evaluate responses of ground-water flow to stormwater-runoff accumulation in the stormwater-control system. The results of the ground-water flow model indicate mean ground-water discharge of 256 acre feet per year, contributing 27 pounds of phosphorus and 765 pounds of nitrogen to Lake Tahoe within the modeled area. Only 0.24 percent of this volume and nutrient load is attributed to stormwater infiltration from the detention basin. Settling of suspended nutrients and sediment, biological assimilation of dissolved nutrients, and sorption and detention of chemicals of potential concern in bottom sediment are the primary stormwater treatments achieved by the detention basins. Mean concentrations of unfiltered nitrogen and phosphorus in inflow stormwater samples compared to outflow samples show that 55 percent of nitrogen and 47 percent of phosphorus are trapped by the detention basin. Organic carbon, cadmium, copper, lead, mercury, nickel, phosphorus, and zinc in the uppermost 0.2 foot of bottom sediment from the detention basin were all at least twice as concentrated compared to sediment collected from 1.5 feet deeper. Similarly, concentrations of 28 polycyclic aromatic hydrocarbon compounds were

  17. Application of the Local Grid Refinement package to an inset model simulating the interactions of lakes, wells, and shallow groundwater, northwestern Waukesha County, Wisconsin

    Science.gov (United States)

    Feinstein, D.T.; Dunning, C.P.; Juckem, P.F.; Hunt, R.J.

    2010-01-01

    Groundwater use from shallow, high-capacity wells is expected to increase across southeastern Wisconsin in the next decade (2010-2020), owing to residential and business growth and the need for shallow water to be blended with deeper water of lesser quality, containing, for example, excessive levels of radium. However, this increased pumping has the potential to affect surface-water features. A previously developed regional groundwater-flow model for southeastern Wisconsin was used as the starting point for a new model to characterize the hydrology of part of northwestern Waukesha County, with a particular focus on the relation between the shallow aquifer and several area lakes. An inset MODFLOW model was embedded in an updated version of the original regional model. Modifications made within the inset model domain include finer grid resolution; representation of Beaver, Pine, and North Lakes by use of the LAK3 package in MODFLOW; and representation of selected stream reaches with the SFR package. Additionally, the inset model is actively linked to the regional model by use of the recently released Local Grid Refinement package for MODFLOW-2005, which allows changes at the regional scale to propagate to the local scale and vice versa. The calibrated inset model was used to simulate the hydrologic system in the Chenequa area under various weather and pumping conditions. The simulated model results for base conditions show that groundwater is the largest inflow component for Beaver Lake (equal to 59 percent of total inflow). For Pine and North Lakes, it is still an important component (equal, respectively, to 16 and 5 percent of total inflow), but for both lakes it is less than the contribution from precipitation and surface water. Severe drought conditions (simulated in a rough way by reducing both precipitation and recharge rates for 5 years to two-thirds of base values) cause correspondingly severe reductions in lake stage and flows. The addition of a test well

  18. Microbial Community Structure in Relation to Water Quality in a Eutrophic Gulf of Mexico Estuary

    Science.gov (United States)

    Weeks Bay is a shallow, microtidal, eutrophic sub-estuary of Mobile Bay, AL. High watershed nutrient inputs to the estuary contribute to a eutrophic condition characterized by frequent summertime diel-cycling hypoxia and dissolved oxygen (DO) oversaturation. Spatial and seasonal ...

  19. Mercury contamination level and speciation inventory in Lakes Titicaca & Uru-Uru (Bolivia): Current status and future trends.

    Science.gov (United States)

    Guédron, S; Point, D; Acha, D; Bouchet, S; Baya, P A; Tessier, E; Monperrus, M; Molina, C I; Groleau, A; Chauvaud, L; Thebault, J; Amice, E; Alanoca, L; Duwig, C; Uzu, G; Lazzaro, X; Bertrand, A; Bertrand, S; Barbraud, C; Delord, K; Gibon, F M; Ibanez, C; Flores, M; Fernandez Saavedra, P; Ezpinoza, M E; Heredia, C; Rocha, F; Zepita, C; Amouroux, D

    2017-12-01

    Aquatic ecosystems of the Bolivian Altiplano (∼3800 m a.s.l.) are characterized by extreme hydro-climatic constrains (e.g., high UV-radiations and low oxygen) and are under the pressure of increasing anthropogenic activities, unregulated mining, agricultural and urban development. We report here a complete inventory of mercury (Hg) levels and speciation in the water column, atmosphere, sediment and key sentinel organisms (i.e., plankton, fish and birds) of two endorheic Lakes of the same watershed differing with respect to their size, eutrophication and contamination levels. Total Hg (THg) and monomethylmercury (MMHg) concentrations in filtered water and sediment of Lake Titicaca are in the lowest range of reported levels in other large lakes worldwide. Downstream, Hg levels are 3-10 times higher in the shallow eutrophic Lake Uru-Uru than in Lake Titicaca due to high Hg inputs from the surrounding mining region. High percentages of MMHg were found in the filtered and unfiltered water rising up from <1 to ∼50% THg from the oligo/hetero-trophic Lake Titicaca to the eutrophic Lake Uru-Uru. Such high %MMHg is explained by a high in situ MMHg production in relation to the sulfate rich substrate, the low oxygen levels of the water column, and the stabilization of MMHg due to abundant ligands present in these alkaline waters. Differences in MMHg concentrations in water and sediments compartments between Lake Titicaca and Uru-Uru were found to mirror the offset in MMHg levels that also exist in their respective food webs. This suggests that in situ MMHg baseline production is likely the main factor controlling MMHg levels in fish species consumed by the local population. Finally, the increase of anthropogenic pressure in Lake Titicaca may probably enhance eutrophication processes which favor MMHg production and thus accumulation in water and biota. Copyright © 2017 Elsevier Ltd. All rights reserved.

  20. Impact of toxic cyanobacteria on gastropods and microcystin accumulation in a eutrophic lake (Grand-Lieu, France) with special reference to Physa (= Physella) acuta

    International Nuclear Information System (INIS)

    Lance, Emilie; Brient, Luc; Carpentier, Alexandre; Acou, Anthony; Marion, Loic; Bormans, Myriam; Gerard, Claudia

    2010-01-01

    Hepatotoxic microcystins (MCs) produced by cyanobacteria are known to accumulate in gastropods following grazing of toxic cyanobacteria and/or absorption of MCs dissolved in water, with adverse effects on life history traits demonstrated in the laboratory. In the field, such effects may vary depending on species, according to their relative sensitivity and ecology. The aims of this study were to i) establish how various intensities of MC-producing cyanobacteria proliferations alter the structure of gastropod community and ii) compare MC tissue concentration in gastropods in the field with those obtained in our previous laboratory experiments on the prosobranch Potamopyrgus antipodarum and the pulmonate Lymnaea stagnalis. We explored these questions through a one-year field study at three stations at Grand-Lieu Lake (France) affected by different intensities of cyanobacteria proliferations. A survey of the community structure and MC content of both cyanobacteria and gastropods was associated with a caging experiment involving P. antipodarum and L. stagnalis. In total, 2592 gastropods belonging to 7 prosobranch and 16 pulmonate species were collected. However, distribution among the stations was unequal with 62% vs 2% of gastropods sampled respectively at the stations with the lowest vs highest concentrations of MC. Irrespective of the station, pulmonates were always more diverse, more abundant and occurred at higher frequencies than prosobranchs. Only the pulmonate Physa acuta occurred at all stations, with abundance and MC tissue concentration (≤ 4.32 μg g DW -1 ) depending on the degrees of MC-producing cyanobacteria proliferations in the stations; therefore, P. acuta is proposed as a potential sentinel species. The caging experiment demonstrated a higher MC accumulation in L. stagnalis (≤ 0.36 μg g DW -1 for 71% of individuals) than in P. antipodarum (≤ 0.02 μg g DW -1 for 12%), corroborating previous laboratory observations. Results are discussed in

  1. Effects of taxonomy, sediment, and water column on C:N:P stoichiometry of submerged macrophytes in Yangtze floodplain shallow lakes, China.

    Science.gov (United States)

    Su, Haojie; Wu, Yao; Xie, Ping; Chen, Jun; Cao, Te; Xia, Wulai

    2016-11-01

    Carbon (C), nitrogen (N) and phosphorus (P) are the three most important essential elements limiting growth of primary producers. Submerged macrophytes generally absorb nutrients from sediments by root uptake. However, the C:N:P stoichiometric signatures of plant tissue are affected by many additional factors such as taxonomy, nutrient availability, and light availability. We first revealed the relative importance of taxonomy, sediment, and water column on plant C:N:P stoichiometry using variance partitioning based on partial redundancy analyses. Results showed that taxonomy was the most important factor in determining C:N:P stoichiometry, then the water column and finally the sediment. In this study, a significant positive relationship was found between community C concentration and macrophyte community biomass, indicating that the local low C availability in macrophytes probably was the main reason why submerged macrophytes declined in Yangtze floodplain shallow lakes. Based on our study, it is suggested that submerged macrophytes in Yangtze floodplain shallow lakes are primarily limited by low light levels rather than nutrient availability.

  2. Identification and determination of the contribution of iron-steel manufacturing industry to sediment-associated polycyclic aromatic hydrocarbons (PAHs) in a large shallow lake of eastern China.

    Science.gov (United States)

    Zhang, Liu; Bai, Ya-Shu; Wang, Ji-Zhong; Peng, Shu-Chuan; Chen, Tian-Hu; Yin, Da-Qiang

    2016-11-01

    Seventeen polycyclic aromatic hydrocarbon (PAH) compounds were determined in surface sediments collected from the Chaohu Lake (a large shallow lake in eastern China) and its tributaries. Both diagnostic ratios and a receptor model (positive matrix factorization, PMF) were applied to identify and determine the contribution of a local iron-steel manufacturing plant located in the Nanfei River (NFR) to the Chaohu Lake basin. The results show that sites located in the downstream of the steel plant contained concentrations of 17 PAH (Σ 17 PAH) approximately two orders of magnitudes higher than those from other sites. Five factors were identified by the PMF model, including industrial waste, wood/biomass burning, diagenetic origin, domestic coal combustion, and industrial combustion. Our findings suggest that sediments in the downstream of the plant and in the western part of the Chaohu Lake were predominantly affected by industrial coal combustion. A mixture of pyrolytic origins impacted urban sediments in the upstream of the plant, whereas diagenetic origins along with coal and biomass burning were suggested to influence the eastern part and rural tributaries of the lake. To assess the potential ecological risk and toxicity caused by the iron-steel plant, sediment toxicity was evaluated by the PMF model, sediment quality guideline, and toxic equivalent factors. All of the three approaches suggested PAH accumulation in the NFR sediments could produce significant adverse ecological effects and half of the sediment toxicity in the NFR may be attributed to the emissions from the iron-steel plant. Some rural locations also exhibited PAH concentrations above probable effects, most likely contributed by wood/biomass burning.

  3. Role of a productive lake in carbon sequestration within a calcareous catchment

    International Nuclear Information System (INIS)

    Nõges, Peeter; Cremona, Fabien; Laas, Alo; Martma, Tõnu; Rõõm, Eva-Ingrid; Toming, Kaire; Viik, Malle; Vilbaste, Sirje; Nõges, Tiina

    2016-01-01

    For a long time, lakes were considered unimportant in the global carbon (C) cycle because of their small total area compared to the ocean. Over the last two decades, a number of studies have highlighted the important role of lakes in both sequestering atmospheric C and modifying the C flux from the catchment by degassing CO_2 and methane and burying calcite and organic matter in the sediment. Based on a full C mass balance, high frequency measurements of lake metabolism and stable isotope analysis of a large shallow eutrophic lake in Estonia, we assess the role alkaline lakes play in augmenting the strength of terrestrial carbonate weathering as a temporary CO_2 sink. We show that a large part of organic C buried in the sediments in this type of lakes originates from the catchment although a direct uptake from the atmosphere during periods of intensive phytoplankton growth in eutrophic conditions contributes to the carbon sink. - Highlights: • Terrestrial carbonate weathering is considered a temporary sink for CO_2_. • Alkaline lakes precipitate calcite reverting chemical weathering reactions. • Algal uptake increased δ"1"3C of dissolved inorganic C while passing through the lake. • 40–70% of sediment organic C originated from catchment alkalinity export. • Biological uptake of released CO_2 counteracts emissions from reversed weathering.

  4. Role of a productive lake in carbon sequestration within a calcareous catchment

    Energy Technology Data Exchange (ETDEWEB)

    Nõges, Peeter, E-mail: peeter.noges@emu.ee [Centre for Limnology, Institute of Agricultural and Environmental Sciences, Estonian University of Life Sciences, 61117 Rannu, Tartu County (Estonia); Cremona, Fabien; Laas, Alo [Centre for Limnology, Institute of Agricultural and Environmental Sciences, Estonian University of Life Sciences, 61117 Rannu, Tartu County (Estonia); Martma, Tõnu [Institute of Geology, Tallinn University of Technology, Ehitajate tee 5, 19086 Tallinn (Estonia); Rõõm, Eva-Ingrid [Centre for Limnology, Institute of Agricultural and Environmental Sciences, Estonian University of Life Sciences, 61117 Rannu, Tartu County (Estonia); Toming, Kaire [Centre for Limnology, Institute of Agricultural and Environmental Sciences, Estonian University of Life Sciences, 61117 Rannu, Tartu County (Estonia); Estonian Marine Institute, University of Tartu, Mäealuse 14, 12618 Tallinn (Estonia); Viik, Malle; Vilbaste, Sirje; Nõges, Tiina [Centre for Limnology, Institute of Agricultural and Environmental Sciences, Estonian University of Life Sciences, 61117 Rannu, Tartu County (Estonia)

    2016-04-15

    For a long time, lakes were considered unimportant in the global carbon (C) cycle because of their small total area compared to the ocean. Over the last two decades, a number of studies have highlighted the important role of lakes in both sequestering atmospheric C and modifying the C flux from the catchment by degassing CO{sub 2} and methane and burying calcite and organic matter in the sediment. Based on a full C mass balance, high frequency measurements of lake metabolism and stable isotope analysis of a large shallow eutrophic lake in Estonia, we assess the role alkaline lakes play in augmenting the strength of terrestrial carbonate weathering as a temporary CO{sub 2} sink. We show that a large part of organic C buried in the sediments in this type of lakes originates from the catchment although a direct uptake from the atmosphere during periods of intensive phytoplankton growth in eutrophic conditions contributes to the carbon sink. - Highlights: • Terrestrial carbonate weathering is considered a temporary sink for CO{sub 2.} • Alkaline lakes precipitate calcite reverting chemical weathering reactions. • Algal uptake increased δ{sup 13}C of dissolved inorganic C while passing through the lake. • 40–70% of sediment organic C originated from catchment alkalinity export. • Biological uptake of released CO{sub 2} counteracts emissions from reversed weathering.

  5. Groundwater flow in a closed basin with a saline shallow lake in a volcanic area: Laguna Tuyajto, northern Chilean Altiplano of the Andes.

    Science.gov (United States)

    Herrera, Christian; Custodio, Emilio; Chong, Guillermo; Lambán, Luis Javier; Riquelme, Rodrigo; Wilke, Hans; Jódar, Jorge; Urrutia, Javier; Urqueta, Harry; Sarmiento, Alvaro; Gamboa, Carolina; Lictevout, Elisabeth

    2016-01-15

    Laguna Tuyajto is a small, shallow saline water lake in the Andean Altiplano of northern Chile. In the eastern side it is fed by springs that discharge groundwater of the nearby volcanic aquifers. The area is arid: rainfall does not exceed 200mm/year in the rainiest parts. The stable isotopic content of spring water shows that the recharge is originated mainly from winter rain, snow melt, and to a lesser extent from some short and intense sporadic rainfall events. Most of the spring water outflowing in the northern side of Laguna Tuyajto is recharged in the Tuyajto volcano. Most of the spring water in the eastern side and groundwater are recharged at higher elevations, in the rims of the nearby endorheic basins of Pampa Colorada and Pampa Las Tecas to the East. The presence of tritium in some deep wells in Pampa Colorada and Pampa Las Tecas indicates recent recharge. Gas emission in recent volcanoes increase the sulfate content of atmospheric deposition and this is reflected in local groundwater. The chemical composition and concentration of spring waters are the result of meteoric water evapo-concentration, water-rock interaction, and mainly the dissolution of old and buried evaporitic deposits. Groundwater flow is mostly shallow due to a low permeability ignimbrite layer of regional extent, which also hinders brine spreading below and around the lake. High deep temperatures near the recent Tuyajto volcano explain the high dissolved silica contents and the δ(18)O shift to heavier values found in some of the spring waters. Laguna Tuyajto is a terminal lake where salts cumulate, mostly halite, but some brine transfer to the Salar de Aguas Calientes-3 cannot be excluded. The hydrogeological behavior of Laguna Tuyajto constitutes a model to understand the functioning of many other similar basins in other areas in the Andean Altiplano. Copyright © 2015 Elsevier B.V. All rights reserved.

  6. Distribution and bioaccumulation of endocrine disrupting chemicals in water, sediment and fishes in a shallow Chinese freshwater lake: Implications for ecological and human health risks.

    Science.gov (United States)

    Dan Liu; Wu, Shengmin; Xu, Huaizhou; Zhang, Qin; Zhang, Shenghu; Shi, Lili; Yao, Cheng; Liu, Yanhua; Cheng, Jie

    2017-06-01

    The occurrence, distribution and bioaccumulation of six endocrine disrupting compounds (EDCs) were investigated in water, sediment and biota samples from Luoma Lake, a shallow Chinese freshwater lake. Total concentrations of ∑phenolic EDCs were much higher than ∑estrogens EDCs in both waters and sediments. There were not obvious differences on the concentrations of target compounds [except nonylphenol (NP)] in upstream, lake and downstream locations, these may be suggested that they were mainly affected by non-point discharges in this area. However, the high concentration of NP in water may be associated with the discharge of rural domestic wastewater without thorough treatment. Furthermore, concentrations of NP were about 2-3 order magnitude higher than those of OP in both water and sediment compartments. Relatively higher bioaccumulation factors (BAF) were obtained for DES and EE2. Ecological risk assessment revealed greater risk of NP in surface water, which may pose a serious threat to aquatic ecosystems. The estrogen equivalent concentration (EEQ) of male were higher than those in female, and occurred in the order of city >rural-urban>countryside. Copyright © 2017 Elsevier Inc. All rights reserved.

  7. Shallow Water Offshore Wind Optimization for the Great Lakes (DE-FOA-0000415) Final Report: A Conceptual Design for Wind Energy in the Great Lakes

    Energy Technology Data Exchange (ETDEWEB)

    Wissemann, Chris [Freshwater Wind I, LLC, Youngstown, OH (United States); White, Stanley M [Stanley White Engineering LLC, Noank, CT (United States)

    2014-02-28

    The primary objective of the project was to develop a innovative Gravity Base Foundation (GBF) concepts, including fabrication yards, launching systems and installation equipment, for a 500MW utility scale project in the Great Lakes (Lake Erie). The goal was to lower the LCOE by 25%. The project was the first to investigate an offshore wind project in the Great Lakes and it has furthered the body of knowledge for foundations and installation methods within Lake Erie. The project collected historical geotechnical information for Lake Erie and also used recently obtained data from the LEEDCo Icebreaker Project (FOA DE-EE0005989) geotechnical program to develop the conceptual designs. Using these data-sets, the project developed design wind and wave conditions from actual buoy data in order to develop a concept that would de-risk a project using a GBF. These wind and wave conditions were then utilized to create reference designs for various foundations specific to installation in Lake Erie. A project partner on the project (Weeks Marine) provided input for construction and costing the GBF fabrication and installation. By having a marine contractor with experience with large marine projects as part of the team provides credibility to the LCOE developed by NREL. NREL then utilized the design and construction costing information as part of the LCOE model. The report summarizes the findings of the project; Developed a cost model and “baseline” LCOE; Documented Site Conditions within Lake Erie; Developed Fabrication, Installation and Foundations Innovative Concept Designs; Evaluated LCOE Impact of Innovations; Developed Assembly line “Rail System” for GBF Construction and Staging; Developed Transit-Inspired Foundation Designs which incorporated: Semi-Floating Transit with Supplemental Pontoons Barge mounted Winch System; Developed GBF with “Penetration Skirt”; Developed Integrated GBF with Turbine Tower; Developed Turbine, Plant Layout and O&M Strategies. The

  8. Calcium Carbonate Phosphate Binding Ion Exchange Filtration and Accelerated Denitrification Improve Public Health Standards and Combat Eutrophication in Aquatic Ecosystems

    OpenAIRE

    Yanamadala, Vijay

    2005-01-01

    Cultural eutrophication, the process by which a lake becomes rich in dissolved nutrients as a result of point and nonpoint pollutant sources, is a major cause of the loss of natural lake ecosystems throughout the world. The process occurs naturally in all lakes, but phosphate-rich nutrient runoff from sources such as storm drains and agricultural runoff is a major cause of excess phosphate-induced eutrophication. Especially in Madrona Marsh, one of the last remaining vernal marshes in the gre...

  9. Spatio-temporal distributions and the ecological and health risks of phthalate esters (PAEs) in the surface water of a large, shallow Chinese lake

    Energy Technology Data Exchange (ETDEWEB)

    He, Wei; Qin, Ning; Kong, Xiangzhen; Liu, Wenxiu; He, Qishuang; Ouyang, Huiling; Yang, Chen; Jiang, Yujiao; Wang, Qingmei; Yang, Bin; Xu, Fuliu, E-mail: xufl@urban.pku.edu.cn

    2013-09-01

    The spatio-temporal distributions and the ecological and health risks of PAEs in surface water of Lake Chaohu, the fifth largest lake in China, were studied based on the monthly monitoring of six PAE congeners from May 2010 to April 2011. The annual total concentration of the six PAE congeners (Σ{sub 6}PAE) in the surface water ranged from 0.467 to 17.953 μg L{sup −1}, with the average value of 4.042 ± 3.929 μg L{sup −1}. The di-n-butyl phthalate (DnBP) that dominated the Σ{sub 6}PAE at 65.8% was found at its highest and lowest levels in the western lake (TX) and eastern drinking water source area (JC), respectively. The temporal distributions of Σ{sub 6}PAE showed that the highest and lowest levels were observed in September 2010 and June 2010, respectively. The different relationships between the runoff and the PAEs with low and high levels of carbon might suggest their different sources. The DnBP had much greater ecological risks than the other studied PAE congeners as indicated by its potential affected fractions (PAFs) and the margin of safety (MOS10). The PAE congeners studied posed little health risk to the nearby male and female citizens. - Highlights: • Monthly variation in PAEs was first investigated in a large Chinese shallow lake. • Ecological and health risks with uncertainty were determined. • PAEs with low and high level of carbon would be from different sources. • DnBP predominated within PAE congeners and posed a much greater ecological risks. • The studied PAE congeners posed little health risks to the nearby citizens.

  10. Environmental and zooplankton parameter changes during the drying of a saline shallow temporary lake in central Argentina

    Directory of Open Access Journals (Sweden)

    Alicia María Vignatti

    2017-09-01

    Full Text Available Central Argentina has numerous saline lakes sustained by groundwater sources and rainfall. These lakes are temporary and experience significant changes in water level and salinity, depending on wet and dry climate cycles. This study aims to investigate the scarcely known dynamics of environmental and zooplankton parameters during the drying phase of one of these lakes. Monthly samples were taken from December 2 012 to July 2 013 in the Ojo de Agua Uriburu lake, previous to its drying. At the beginning of the study, the lake’s depth was 0.7 m and its salinity was 16.65 g L−1, later, in July, its depth decreased to 0.06 m and its salinity increased to 92.9 g L−1. Zooplankton species richness was low (three crustaceans and three rotifers, with Boeckella poopoensis and Moina eugeniae dominating in the system. Maximum density and biomass were attained by the two dominant species in April (318.5 i nd L−1 and 3 029.1 µg L−1 dry weight; and 242.4 i nd L −1 and 1 530.4 µg L−1 dry weight, for B. poopoensis and M. ugeniae, respectively, and no correlation was found between these parameters and salinity. Maximum average body lengths for both species were observed in the last months of sampling (M. eugeniae: 1 020 ± 84.2 µm and B. poopoensis: 1 348.8 ± 89.0 µm. At this point of the study, neither juvenile nor larval stages were found. The increase in average body size is, arguably, the result of increased salinity in the system through a negative effect on reproduction. Because this lake reached hypersalinity, its ecological dynamics are unique among those of other temporary, saline lakes that dried in central Argentina. Similar studies on other temporary ecosystems are needed to increase the information on these little known ecological aspects.

  11. The role of light for fish-zooplankton-phytoplankton interactions during winter in shallow lakes - a climate change perspective

    DEFF Research Database (Denmark)

    Bramm, Mette Elisabeth; Lassen, Majbritt Kjeldahl; Liboriussen, Lone

    2009-01-01

    in the life history of copepods. The strength of the fish effect on zooplankton biomass diminished with declining light and the effect of light was strongest in the presence of fish. 4. When fish were present, reduced light led to a shift from rotifers to calanoid copepods in the clear lake and from rotifers...... in winter light conditions are needed in order to have a significant effect on the plankton community. The change in light occurring when such plankton communities move northwards in response to global warming will mostly be of modest importance for this lake type, at least for the rest of this century...

  12. ERS-1 SAR monitoring of ice growth on shallow lakes to determine water depth and availability in north west Alaska

    Science.gov (United States)

    Jeffries, Martin; Morris, Kim; Liston, Glen

    1996-01-01

    Images taken by the ERS-1 synthetic aperture radar (SAR) were used to identify and to differentiate between the lakes that freeze completely to the bottom and those that do not, on the North Slope, in northwestern Alaska. The ice thickness at the time each lake froze completely is determined with numerical ice growth model that gives a maximum simulated thickness of 2.2 m. A method combining the ERS-1 SAR images and numerical ice growth model was used to determine the ice growth and the water availability in these regions.

  13. Avoidance reactions of fish in the trawl mouth opening in a shallow and turbid lake at night

    Czech Academy of Sciences Publication Activity Database

    Jůza, Tomáš; Rakowitz, G.; Draštík, Vladislav; Blabolil, Petr; Herzig, A.; Kratochvíl, Michal; Muška, Milan; Říha, Milan; Sajdlová, Zuzana; Kubečka, Jan

    2013-01-01

    Roč. 147, October (2013), s. 154-160 ISSN 0165-7836 R&D Projects: GA MŠk(CZ) EE2.3.20.0204 Institutional support: RVO:60077344 Keywords : Lake Neusiedl * trawl * DIDSON * fish abundance * biomass Subject RIV: EH - Ecology, Behaviour Impact factor: 1.843, year: 2013

  14. Succession of Periphyton and Phytoplankton Assemblages in Years with Varying Amounts of Precipitation in a Shallow Urban Lake (Lake Jeziorak Mały, Poland)

    OpenAIRE

    Zębek Elžbieta

    2014-01-01

    This study of periphyton assemblages (periphyton in separator pipes, epilithon and epiphyton) and phytoplankton was carried out in Lake Jeziorak Maly in 1997-2003 and 2005. Since precipitation amounts varied in these years, changes in the abundance, biomass, taxonomic group structure, spe-cies diversity and dominant taxa of these assemblages were analyzed in relation to the physical and chemical water parameters. The periphyton in pipes had their highest abundance and biomass at the mean prec...

  15. Carbon flows in eutrophic Lake Rotsee: a

    NARCIS (Netherlands)

    Lammers, J.M.; Schubert, C. J.; Reichart, G.-J.

    2016-01-01

    The microbial segment of food webs playsa crucial role in lacustrine food-web functioning andcarbon transfer, thereby influencing carbon storageand CO2 emission and uptake in freshwater environments.Variability in microbial carbon processing(autotrophic and heterotrophic production and

  16. Physical Factors Correlate to Microbial Community Structure and Nitrogen Cycling Gene Abundance in a Nitrate Fed Eutrophic Lagoon.

    Science.gov (United States)

    Highton, Matthew P; Roosa, Stéphanie; Crawshaw, Josie; Schallenberg, Marc; Morales, Sergio E

    2016-01-01

    Nitrogenous run-off from farmed pastures contributes to the eutrophication of Lake Ellesmere, a large shallow lagoon/lake on the east coast of New Zealand. Tributaries periodically deliver high loads of nitrate to the lake which likely affect microbial communities therein. We hypothesized that a nutrient gradient would form from the potential sources (tributaries) creating a disturbance resulting in changes in microbial community structure. To test this we first determined the existence of such a gradient but found only a weak nitrogen (TN) and phosphorous gradient (DRP). Changes in microbial communities were determined by measuring functional potential (quantification of nitrogen cycling genes via nifH , nirS , nosZI , and nosZII using qPCR), potential activity (via denitrification enzyme activity), as well as using changes in total community (via 16S rRNA gene amplicon sequencing). Our results demonstrated that changes in microbial communities at a phylogenetic (relative abundance) and functional level (proportion of the microbial community carrying nifH and nosZI genes) were most strongly associated with physical gradients (e.g., lake depth, sediment grain size, sediment porosity) and not nutrient concentrations. Low nitrate influx at the time of sampling is proposed as a factor contributing to the observed patterns.

  17. Physical factors correlate to microbial community structure and nitrogen cycling gene abundance in a nitrate fed eutrophic lagoon

    Directory of Open Access Journals (Sweden)

    Matthew Paul Highton

    2016-10-01

    Full Text Available Nitrogenous run-off from farmed pastures contributes to the eutrophication of Lake Ellesmere, a large shallow lagoon/lake on the east coast of New Zealand. Tributaries periodically deliver high loads of nitrate to the lake which likely affect microbial communities therein. We hypothesized that a nutrient gradient would form from the potential sources (tributaries creating a disturbance resulting in changes in microbial community structure. To test this we first determined the existence of such a gradient but found only a weak nitrogen (TN and phosphorous gradient (DRP. Changes in microbial communities were determined by measuring functional potential (quantification of nitrogen cycling genes via nifH, nirS, nosZI and nosZII using qPCR, potential activity (via denitrification enzyme activity, as well as using changes in total community (via 16S rRNA gene amplicon sequencing. Our results demonstrated that changes in microbial communities at a phylogenetic (relative abundance and functional level (proportion of the microbial community carrying nifH and nosZI genes were most strongly associated with physical gradients (e.g. lake depth, sediment grain size, sediment porosity and not nutrient concentrations. Low nitrate influx at the time of sampling is proposed as a factor contributing to the observed patterns.

  18. Assessment of multi-trophic changes in a shallow boreal lake simultaneously exposed to climate change and aerial deposition of contaminants from the Athabasca Oil Sands Region, Canada.

    Science.gov (United States)

    Summers, Jamie C; Kurek, Joshua; Rühland, Kathleen M; Neville, Erin E; Smol, John P

    2017-08-15

    The Athabasca Oil Sands Region (AOSR) has been intensely developed for industrial bitumen extraction and upgrading since the 1980s. A paucity of environmental monitoring prior to development raises questions about baseline conditions in freshwater systems in the region and ecological responses to industrial activities. Further, climatic changes prompt questions about the relative roles of climate and industry in shaping aquatic ecosystems through time. We use aquatic bioindicators from multiple trophic levels, concentrations of petrogenic contaminants (dibenzothiophenes), and spectrally-inferred chlorophyll-a preserved in well-dated sediments of a closed-basin, shallow lake ~50km away from the main area of industry, in conjunction with climate observations, to assess how the biotic assemblages of a typical AOSR lake have changed during the past ~75years. We examine the contributions of the area's stressors in structuring aquatic communities. Increases in sedimentary measures of petrogenic contaminants provide clear evidence of aerial contaminant deposition from local industry since its establishment, while climate records demonstrate consistent warming and a recent period of reduced precipitation. Quantitative comparisons of biological assemblages from before and after the establishment of regional industry find significant (pshallow systems. Copyright © 2017 Elsevier B.V. All rights reserved.

  19. Occurrence of pharmaceuticals and personal care products, and their associated environmental risks in a large shallow lake in north China.

    Science.gov (United States)

    Zhang, Panwei; Zhou, Huaidong; Li, Kun; Zhao, Xiaohui; Liu, Qiaona; Li, Dongjiao; Zhao, Gaofeng

    2018-01-13

    Eighteen selected pharmaceuticals and personal care products (PPCPs), consisting of five non-antibiotic pharmaceuticals (N-APs), four sulfonamides (SAs), four tetracyclines (TCs), four macrolides (MCs), and one quinolone (QN) were detected in water, pore water, and sediment samples from Baiyangdian Lake, China. A total of 31 water samples and 29 sediment samples were collected in March 2017. Caffeine was detected with 100% frequency in surface water, pore water, and sediment samples. Carbamazepine was detected with 100% frequency in surface water and sediment samples. Five N-APs were prominent, with mean concentrations of 4.90-266.24 ng/l in surface water and 5.07-14.73 μg/kg in sediment samples. Four MCs were prominent, with mean concentrations of 0.97-29.92 ng/l in pore water samples. The total concentrations of the different classes of PPCPs followed the order: N-APs (53.26%) > MCs (25.39) > SAs (10.06%) > TCs (7.64%) > QNs (3.64%) in surface water; N-APs (42.70%) > MCs (25.43%) > TCs (14.69%) > SAs (13.90%) > QNs (3.24%) in sediment samples, and MCs (42.12%) > N-APs (34.80%) > SAs (11.71%) > TCs (7.48%) > QNs (3.88%) in pore water samples. The geographical differences of PPCP concentrations were largely due to anthropogenic activities. Sewage discharged from Baoding City and human activities around Baiyangdian Lake were the main sources of PPCPs in the lake. An environmental risk assessment for the upper quartile concentration was undertaken using calculated risk quotients and indicated a low or medium-high risk from 18 PPCPs in Baiyangdian Lake and its five upstream rivers.

  20. Structural Composition of Protozooplankton Communities in Relation to Environmental Factors in Shallow Lakes and Reservoirs of Rīga, Latvia

    Directory of Open Access Journals (Sweden)

    Buholce Linda

    2015-08-01

    Full Text Available Protozooplankton are dominant grazers of phytoplankton and an important component of the microbial food web, as a link between pico and nanoplankton to higher trophic levels. Their fast growing rate, relative abundance, biomass and diversity are used as indicators of organic and toxic pollution. The impact of urbanisation on ecosystems and their sustainability and biodiversity have recently been much studied. We studied the protozooplankton ciliate communities during the vegetation period from April to October in two small lakes (Bābelītis, Gaiļezers and two reservoirs (Bolderāja, Saurieši. The largest peak of biomass (15.7 × 102 mg/l was found in Gaiļezers Lake in August and of abundance (60.2 × 103 org/l in Bābelītis Lake in July. The lowest biomass (0.006 mg/l and abundance (0.12 × 103 org/l were found in the Saurieši Reservoir station. The most abundant ciliates were from the order Oligotrichida.

  1. Will the Displacement of Zebra Mussels by Quagga Mussels Increase Water Clarity in Shallow Lakes during Summer? Results from a Mesocosm Experiment.

    Directory of Open Access Journals (Sweden)

    Xueying Mei

    Full Text Available Zebra mussels (Dreissena polymorpha are known to increase water clarity and affect ecosystem processes in invaded lakes. During the last decade, the conspecific quagga mussels (D. rostriformis bugensis have displaced zebra mussels in many ecosystems including shallow lakes such as Oneida Lake, New York. In this study, an eight-week mesocosm experiment was conducted to test the hypothesis that the displacement of zebra mussels by quagga mussels leads to further decreases in phytoplankton and increases in water clarity resulting in increases in benthic algae. We found that the presence of zebra mussels alone (ZM, quagga mussels alone (QM, or an equal number of both species (ZQ reduced total phosphorus (TP and phytoplankton Chl a. Total suspended solids (TSS was reduced in ZM and ZQ treatments. Light intensity at the sediment surface was higher in all three mussel treatments than in the no-mussel controls but there was no difference among the mussel treatments. There was no increase in benthic algae biomass in the mussel treatments compared with the no-mussel controls. Importantly, there was no significant difference in nutrient (TP, soluble reactive phosphorus and NO3- levels, TSS, phytoplankton Chl a, benthic algal Chl a, or light intensity on the sediment surface between ZM, QM and ZQ treatments. These results confirm the strong effect of both mussel species on water clarity and indicate that the displacement of zebra mussel by an equivalent biomass of quagga mussel is not likely to lead to further increases in water clarity, at least for the limnological conditions, including summer temperature, tested in this experiment.

  2. Will the Displacement of Zebra Mussels by Quagga Mussels Increase Water Clarity in Shallow Lakes during Summer? Results from a Mesocosm Experiment.

    Science.gov (United States)

    Mei, Xueying; Zhang, Xiufeng; Kassam, Sinan-Saleh; Rudstam, Lars G

    2016-01-01

    Zebra mussels (Dreissena polymorpha) are known to increase water clarity and affect ecosystem processes in invaded lakes. During the last decade, the conspecific quagga mussels (D. rostriformis bugensis) have displaced zebra mussels in many ecosystems including shallow lakes such as Oneida Lake, New York. In this study, an eight-week mesocosm experiment was conducted to test the hypothesis that the displacement of zebra mussels by quagga mussels leads to further decreases in phytoplankton and increases in water clarity resulting in increases in benthic algae. We found that the presence of zebra mussels alone (ZM), quagga mussels alone (QM), or an equal number of both species (ZQ) reduced total phosphorus (TP) and phytoplankton Chl a. Total suspended solids (TSS) was reduced in ZM and ZQ treatments. Light intensity at the sediment surface was higher in all three mussel treatments than in the no-mussel controls but there was no difference among the mussel treatments. There was no increase in benthic algae biomass in the mussel treatments compared with the no-mussel controls. Importantly, there was no significant difference in nutrient (TP, soluble reactive phosphorus and NO3-) levels, TSS, phytoplankton Chl a, benthic algal Chl a, or light intensity on the sediment surface between ZM, QM and ZQ treatments. These results confirm the strong effect of both mussel species on water clarity and indicate that the displacement of zebra mussel by an equivalent biomass of quagga mussel is not likely to lead to further increases in water clarity, at least for the limnological conditions, including summer temperature, tested in this experiment.

  3. Induced calcite precipitation for the restoration of stratified hardwater lakes: The case of Lake Schmaler Luzin (North-East Germany); Induzierte Calcitfaellung zur Restaurierung eutropher Seen am Beispiel des Schmalen Luzins (Nord-Ost-Deutschland)

    Energy Technology Data Exchange (ETDEWEB)

    Dittrich, M.; Heiser, A.; Koschel, R. [Inst. fuer Gewaesseroekologie und Binnenfischerei, Neuglobsow (Germany). Abt. fuer Limnologie Geschichteter Seen

    1997-11-01

    Artificially induced calcite precipitation combined with deep water aeration has been tested as a possible technology for lake restoration. A pilot equipment for whole lake experiments has been developed for the restoration of the Lake Schmaler Luzin on the basis of enclosure experiments. The hypolimnetic calcite precipitation was induced by hypolimnetic addition of Ca(OH){sub 2}. In 1996 the first experiments were aimed at checking the conditions for artificially induced hypolimnetic calcite precipitation and their effectiveness on phosphorus elimination. 140 t Ca(OH){sub 2} and 416 000 m{sup 3} air were added in the hypolimnion during two cycles of these experiments, each lasting one month. This led to an increase of the pH value in the hypolimnion from 7.2 to 9.1, above the sediment (2-3 cm) from 7.2 to 8.2 and in the upper layers of sediments from 7.4 to 8.6. The chemical equilibrium was shifted towards the calcite and we observed hypolimnetic calcite precipitations. In 1996 the hypolimnetic aeration was performed with the aim of homogenisation of the hypolimnion. As expected the amount of added air was not enough to make the whole hypolimnion aerobic during the summer stagnation. The reduction of the total and dissolved phosphorus concentration in the hypolimnion and at the sediment-water interface in comparison to the values of the year before indicated the occurence of phosphorus coprecipitation with calcite. The concentration of the soluble reactive phosphorus above the sediment decreased from 0.31 mgl{sup -1} in 1995 (26.07.) to 0.04 mgl{sup -1} in 1996 (01.08.). (orig.) [Deutsch] Basirend auf den Ergebnissen von Enclosureversuchen wurde 1995/96 eine Pilotanlage zur Restaurierung geschichteter eutrophierter und kalkreicher Seen entwickelt. Die Pilotanlage kombiniert die hypolimnische Ca(OH){sub 2}-Zugabe mit einer Tiefenwasserbelueftung. Die Anlage hat 1996 ihren Betrieb aufgenommen und wird zur Restaurierung des ehemals oligotrophen, jetzt eutrophen

  4. Performance of surface and subsurface flow constructed wetlands treating eutrophic waters.

    Science.gov (United States)

    Hernández-Crespo, C; Gargallo, S; Benedito-Durá, V; Nácher-Rodríguez, Beatriz; Rodrigo-Alacreu, M A; Martín, M

    2017-10-01

    Three medium size constructed wetlands (CWs) with a total surface of 90ha are working since 2009 in the Albufera de Valencia Natural Park (Spain). Two of them are fed with eutrophic waters from l'Albufera Lake. Their objectives are both reduce the phytoplankton biomass and increase the biodiversity; consequently, improved water quality is returned to the lake. A "science based governance" of these CWs is ongoing inside the LIFE+12 Albufera Project to demonstrate the environmental benefits of these features. In this paper, results and relationships among hydraulic operation, physicochemical variables and plankton in two different CWs typologies, five free water surface CW (FWSCW) and one horizontal subsurface flow CW (HSSFCW), were analysed showing that CWs were capable of improving the water quality and biodiversity but showing clear differences depending on the CW type. The CWs worked under different hydraulic load rates (HLR) from <0.12 to 54.75myr -1 . Inflow water quality was typical from eutrophic waters with mean values of chlorophyll a (Chl a) about 22-90μgChlal -1 and mean total phosphorus (TP) between 0.122 and 0.337mgl -1 . The main conclusion is that HSSFCW was much more efficient than FWSCW in the removal of organic matter, suspended solids and nutrients. The biological role of several shallow lagoons located at the end of the CWs has also been evaluated, showing that they contribute to increase the zooplankton biomass, a key factor to control the phytoplankton blooms. Copyright © 2017 Elsevier B.V. All rights reserved.

  5. Groundwater flow in a closed basin with a saline shallow lake in a volcanic area: Laguna Tuyajto, northern Chilean Altiplano of the Andes

    International Nuclear Information System (INIS)

    Herrera, Christian; Custodio, Emilio; Chong, Guillermo; Lambán, Luis Javier; Riquelme, Rodrigo; Wilke, Hans; Jódar, Jorge; Urrutia, Javier; Urqueta, Harry; Sarmiento, Alvaro

    2016-01-01

    Laguna Tuyajto is a small, shallow saline water lake in the Andean Altiplano of northern Chile. In the eastern side it is fed by springs that discharge groundwater of the nearby volcanic aquifers. The area is arid: rainfall does not exceed 200 mm/year in the rainiest parts. The stable isotopic content of spring water shows that the recharge is originated mainly from winter rain, snow melt, and to a lesser extent from some short and intense sporadic rainfall events. Most of the spring water outflowing in the northern side of Laguna Tuyajto is recharged in the Tuyajto volcano. Most of the spring water in the eastern side and groundwater are recharged at higher elevations, in the rims of the nearby endorheic basins of Pampa Colorada and Pampa Las Tecas to the East. The presence of tritium in some deep wells in Pampa Colorada and Pampa Las Tecas indicates recent recharge. Gas emission in recent volcanoes increase the sulfate content of atmospheric deposition and this is reflected in local groundwater. The chemical composition and concentration of spring waters are the result of meteoric water evapo-concentration, water–rock interaction, and mainly the dissolution of old and buried evaporitic deposits. Groundwater flow is mostly shallow due to a low permeability ignimbrite layer of regional extent, which also hinders brine spreading below and around the lake. High deep temperatures near the recent Tuyajto volcano explain the high dissolved silica contents and the δ"1"8O shift to heavier values found in some of the spring waters. Laguna Tuyajto is a terminal lake where salts cumulate, mostly halite, but some brine transfer to the Salar de Aguas Calientes-3 cannot be excluded. The hydrogeological behavior of Laguna Tuyajto constitutes a model to understand the functioning of many other similar basins in other areas in the Andean Altiplano. - Highlights: • Recent volcanism formations play a key role in producing recharge. • Groundwater can flow across local

  6. Groundwater flow in a closed basin with a saline shallow lake in a volcanic area: Laguna Tuyajto, northern Chilean Altiplano of the Andes

    Energy Technology Data Exchange (ETDEWEB)

    Herrera, Christian, E-mail: cherrera@ucn.cl [Departamento de Ciencias Geológicas, Universidad Católica del Norte, Casilla 1280, Antofagasta (Chile); Centro de Investigación Tecnológica del Agua en el Desierto (CEITSAZA), Universidad Católica del Norte, Casilla 1280, Antofagasta (Chile); Custodio, Emilio [Department of Geo-Engineering, Technical University of Catalonia/Barcelona Tech (UPC), Barcelona (Spain); Chong, Guillermo [Departamento de Ciencias Geológicas, Universidad Católica del Norte, Casilla 1280, Antofagasta (Chile); Lambán, Luis Javier [Geological Institute of Spain (IGME), Zaragoza (Spain); Riquelme, Rodrigo; Wilke, Hans [Departamento de Ciencias Geológicas, Universidad Católica del Norte, Casilla 1280, Antofagasta (Chile); Jódar, Jorge [Department of Geo-Engineering, Technical University of Catalonia/Barcelona Tech (UPC), Barcelona (Spain); Urrutia, Javier; Urqueta, Harry [Departamento de Ciencias Geológicas, Universidad Católica del Norte, Casilla 1280, Antofagasta (Chile); Centro de Investigación Tecnológica del Agua en el Desierto (CEITSAZA), Universidad Católica del Norte, Casilla 1280, Antofagasta (Chile); Sarmiento, Alvaro [Departamento de Ciencias Geológicas, Universidad Católica del Norte, Casilla 1280, Antofagasta (Chile); and others

    2016-01-15

    Laguna Tuyajto is a small, shallow saline water lake in the Andean Altiplano of northern Chile. In the eastern side it is fed by springs that discharge groundwater of the nearby volcanic aquifers. The area is arid: rainfall does not exceed 200 mm/year in the rainiest parts. The stable isotopic content of spring water shows that the recharge is originated mainly from winter rain, snow melt, and to a lesser extent from some short and intense sporadic rainfall events. Most of the spring water outflowing in the northern side of Laguna Tuyajto is recharged in the Tuyajto volcano. Most of the spring water in the eastern side and groundwater are recharged at higher elevations, in the rims of the nearby endorheic basins of Pampa Colorada and Pampa Las Tecas to the East. The presence of tritium in some deep wells in Pampa Colorada and Pampa Las Tecas indicates recent recharge. Gas emission in recent volcanoes increase the sulfate content of atmospheric deposition and this is reflected in local groundwater. The chemical composition and concentration of spring waters are the result of meteoric water evapo-concentration, water–rock interaction, and mainly the dissolution of old and buried evaporitic deposits. Groundwater flow is mostly shallow due to a low permeability ignimbrite layer of regional extent, which also hinders brine spreading below and around the lake. High deep temperatures near the recent Tuyajto volcano explain the high dissolved silica contents and the δ{sup 18}O shift to heavier values found in some of the spring waters. Laguna Tuyajto is a terminal lake where salts cumulate, mostly halite, but some brine transfer to the Salar de Aguas Calientes-3 cannot be excluded. The hydrogeological behavior of Laguna Tuyajto constitutes a model to understand the functioning of many other similar basins in other areas in the Andean Altiplano. - Highlights: • Recent volcanism formations play a key role in producing recharge. • Groundwater can flow across local

  7. Cogs in the endless machine: lakes, climate change and nutrient cycles: a review.

    Science.gov (United States)

    Moss, Brian

    2012-09-15

    Lakes have, rather grandly, been described as sentinels, integrators and regulators of climate change (Williamson et al., Limnol. Oceanogr. 2009; 54: 2273-82). Lakes are also part of the continuum of the water cycle, cogs in a machine that processes water and elements dissolved and suspended in myriad forms. Assessing the changes in the functioning of the cogs and the machine with respect to these substances as climate changes is clearly important, but difficult. Many other human-induced influences, not least eutrophication, that impact on catchment areas and consequently on lakes, have generally complicated the recording of recent change in sediment records and modern sets of data. The least confounded evidence comes from remote lakes in mountain and polar regions and suggests effects of warming that include mobilisation of ions and increased amounts of phosphorus. A cottage industry has arisen in deduction and prediction of the future effects of climate change on lakes, but the results are very general and precision is marred not only by confounding influences but by the complexity of the lake system and the infinite variety of possible future scenarios. A common conclusion, however, is that warming will increase the intensity of symptoms of eutrophication. Direct experimentation, though expensive and still unusual and confined to shallow lake and wetland systems is perhaps the most reliable approach. Results suggest increased symptoms of eutrophication, and changes in ecosystem structure, but in some respects are different from those deduced from comparisons along latitudinal gradients or by inference from knowledge of lake behaviour. Experiments have shown marked increases in community respiration compared with gross photosynthesis in mesocosm systems and it may be that the most significant churnings of these cogs in the earth-air-water machine will be in their influence on the carbon cycle, with possibly large positive feedback effects on warming. Copyright

  8. Variation of phytoplankton functional groups modulated by hydraulic controls in Hongze Lake, China.

    Science.gov (United States)

    Tian, Chang; Pei, Haiyan; Hu, Wenrong; Hao, Daping; Doblin, Martina A; Ren, Ying; Wei, Jielin; Feng, Yawei

    2015-11-01

    Hongze Lake is a large, shallow, polymictic, eutrophic lake in the eastern China. Phytoplankton functional groups in this lake were investigated from March 2011 to February 2013, and a comparison was made between the eastern, western, and northern regions. The lake shows strong fluctuations in water level caused by monsoon rains and regular hydraulic controls. By application of the phytoplankton functional group approach, this study aims to investigate the spatial and temporal dynamics and analyze their influencing factors. Altogether, 18 functional groups of phytoplankton were identified, encompassing 187 species. In order to seek the best variable describing the phytoplankton functional group distribution, 14 of the groups were analyzed in detail using redundancy analysis. Due to the turbid condition of the lake, the dominant functional groups were those tolerant of low light. The predominant functional groups in the annual succession were D (Cyclotella spp. and Synedra acus), T (Planctonema lauterbornii), P (Fragilaria crotonensis), X1 (Chlorella vulgaris and Chlorella pyrenoidosa), C (Cyclotella meneghiniana and Cyclotella ocellata), and Y (Cryptomonas erosa). An opposite relationship between water level and the biomass of predominant groups was observed in the present study. Water level fluctuations, caused by monsoonal climate and artificial drawdown, were significant factors influencing phytoplankton succession in Hongze Lake, since they alter the hydrological conditions and influence light and nutrient availability. The clearly demonstrated factors, which significantly influence phytoplankton dynamics in Hongze Lake, will help government manage the large shallow lakes with frequent water level fluctuations.

  9. Characterizing the Fate and Mobility of Phosphorus in Utah Lake Sediments

    Science.gov (United States)

    Carling, G. T.; Randall, M.; Nelson, S.; Rey, K.; Hansen, N.; Bickmore, B.; Miller, T.

    2017-12-01

    An increasing number of lakes worldwide are impacted by eutrophication and harmful algal blooms due to anthropogenic nutrient inputs. Utah Lake is a unique eutrophic freshwater lake that is naturally shallow, turbid, and alkaline with high dissolved oxygen levels that has experienced severe algal blooms in recent years. Recently, the Utah Division of Water Quality has proposed a new limitation of phosphorus (P) loading to Utah Lake from wastewater treatment plants in an effort to mitigate eutrophication. However, reducing external P loads may not lead to immediate improvements in water quality due to the legacy pool of nutrients in lake sediments. The purpose of this study was to characterize the fate and mobility of P in Utah Lake sediments to better understand P cycling in this unique system. We analyzed P speciation, mineralogy, and binding capacity in lake sediment samples collected from 15 locations across Utah Lake. P concentrations in sediment ranged from 615 to 1894 ppm, with highest concentrations in Provo Bay near the major metropolitan area. Sequential leach tests indicate that 25-50% of P is associated with Ca (CaCO₃/ Ca10(PO4)6(OH,F,Cl)2 ≈ P) and 40-60% is associated with Fe (Fe(OOH) ≈ P). Ca-associated P was confirmed by SEM images, which showed the highest P concentrations correlating with Ca (carbonate minerals/apatite). The Ca-associated P fraction is likely immobile, but the Fe-bound P is potentially bioavailable under changing redox conditions. Batch sorption results indicate that lake sediments have a high capacity to absorb and remove P from the water column, with an average uptake of 70-96% removal over the range of 1-10 mg/L P. Mineral precipitation and sorption to bottom sediments is an efficient removal mechanism of P in Utah Lake, but a significant portion of P may be temporarily available for resuspension and cycling in surface waters. Mitigating lake eutrophication is a complex problem that goes beyond decreasing external nutrient

  10. Field scale interaction and nutrient exchange between surface water and shallow groundwater in the Baiyang Lake region, North China Plain

    DEFF Research Database (Denmark)

    Brauns, Bentje; Bjerg, Poul Løgstrup; Song, Xianfang

    2016-01-01

    in Hebei Province, China, was undertaken. The study showed a high influence of low-quality surface water on the shallow aquifer. Major inflowing pollutants into the aquifer were ammonium and nitrate via inflow from the adjacent Fu River (up to 29.8mg/L NH4-N and 6.8mg/L NO3-N), as well as nitrate via...... vertical transport from the field surface (up to 134.8mg/L NO3-N in soil water). Results from a conceptual model show an excess nitrogen input of about 320kg/ha/a. Nevertheless, both nitrogen species were only detected at low concentrations in shallow groundwater, averaging at 3.6mg/L NH4-N and 1.8mg/L NO3......-N. Measurement results supported by PHREEQC-modeling indicated cation exchange, denitrification, and anaerobic ammonium oxidation coupled with partial denitrification as major nitrogen removal pathways. Despite the current removal capacity, the excessive nitrogen fertilization may pose a future...

  11. Role of a productive lake in carbon sequestration within a calcareous catchment.

    Science.gov (United States)

    Nõges, Peeter; Cremona, Fabien; Laas, Alo; Martma, Tõnu; Rõõm, Eva-Ingrid; Toming, Kaire; Viik, Malle; Vilbaste, Sirje; Nõges, Tiina

    2016-04-15

    For a long time, lakes were considered unimportant in the global carbon (C) cycle because of their small total area compared to the ocean. Over the last two decades, a number of studies have highlighted the important role of lakes in both sequestering atmospheric C and modifying the C flux from the catchment by degassing CO2 and methane and burying calcite and organic matter in the sediment. Based on a full C mass balance, high frequency measurements of lake metabolism and stable isotope analysis of a large shallow eutrophic lake in Estonia, we assess the role alkaline lakes play in augmenting the strength of terrestrial carbonate weathering as a temporary CO2 sink. We show that a large part of organic C buried in the sediments in this type of lakes originates from the catchment although a direct uptake from the atmosphere during periods of intensive phytoplankton growth in eutrophic conditions contributes to the carbon sink. Copyright © 2016 Elsevier B.V. All rights reserved.

  12. Spatial uniformity in depth optima of midges: evidence from sedimentary archives of shallow Alpine and boreal lakes

    Directory of Open Access Journals (Sweden)

    Tomi P. Luoto

    2012-01-01

    Full Text Available In this study, water depth optima, i.e. habitat preferences within a depth gradient, were estimated for mutual midge (Diptera: Nematocera; Ceratopogonidae, Chironomidae taxa in surface sediment intralake data sets from eastern Finland and Austrian Alps and in a regional data set across Finland. The aim was to investigate how the optima and tolerances differ in these data sets and to discuss whether the possible causal factor for deviance is related to local adaptation, taxa representativeness, or some other factor. A total of 20 mutual taxa were found from the data sets and the estimated optima and tolerances were highly similar, with the exception of three taxa, which had deviating optima in the Austrian lake. The reason for these differences was most likely that the optima were poorly estimated in the Austrian lake due to low abundances and number of occurrences of these taxa. No evidence for intraspecific niche separation or local habitat adaptation was found between the Austrian and Finnish sites, although, interspecific variation in habitats was evident. Therefore, water depth optima estimated from representative number of specimens may be applicable for various ecological, limnological, and paleolimnological purposes. However, when the optima are applied outside the data set’s coverage, the results should be interpreted with caution. In addition, the given optima are not applicable in sites deeper than the sites in the data sets.

  13. Seasonality of Water Chemistry, Carbonate Production, and Biometric Features of Two Species of Chara in a Shallow Clear Water Lake

    Directory of Open Access Journals (Sweden)

    Andrzej Pukacz

    2014-01-01

    Full Text Available The objective of this study was to analyze the temporal variability of biometric features and the carbonate production of two charophytes: Chara polyacantha A. Braun and Chara rudis A. Braun against the background of the physical-chemical properties of water. The investigation was carried out in a small, mid-forest Lake Jasne (western Poland. It is a polymictic, mesotrophic, hardwater ecosystem dominated by charophyte vegetation. Each month, 10 individuals of each species were characterized in terms of morphometric features, fresh and dry weight, and the percentage of calcium carbonate. Additionally, physical-chemical parameters of the water were studied. The results of physical-chemical analyses indicated similar habitat conditions for both species. Despite smaller dry weight C. polyacantha was characterized by greater morphological variability and higher rates of growth and percentage share of calcium carbonate in dry mass than C. rudis. The percentage of calcium carbonates in dry mass did not differ significantly between the species and exceeded 60%, reaching the maximum (76% in C. polyacantha in July and August. For both species, distinct correlations between the structure of biomass and morphological features were found. The obtained results show the great importance of charophyte vegetation in carbon cycling and functioning of lake ecosystems.

  14. Spatiotemporal distribution of algal and nutrient, and their correlations based on long-term monitoring data in Lake Taihu, China

    Science.gov (United States)

    Acharya, K.; Li, Y.; Stone, M.; Yu, Z.; Young, M.; Shafer, D. S.; Zhu, J.; Warwick, J. J.

    2009-12-01

    Eutrophication in Lake Taihu - China’s third largest freshwater lake - has led to deterioration of water quality and caused more frequent cyanobacteria blooms at many lake locations in recent years. Eutrophication is thought to be fueled by increased nutrient loading, a consequence of rapid population and economic growth in the region. To understand the spatiotemporal distribution of algal blooms, a database was developed that includes long-term meteorological, hydrological, water quality, and socioeconomic data from the Lake Taihu watershed. The data were collected through various field observations, and augmented with information from local and provincial agencies, and universities. Based on the data, spatiotemporal distributions of, and correlations between, chlorophyll-a (Chl-a), total phosphorus (TP), total nitrogen (TN) and water temperature (WT) were analyzed. Results revealed a high degree of correlation between TP and Chl-a concentrations during warm seasons, with high concentrations of both substances present in the northern and northwest portions of the lake. During winter months, Chl-a concentrations were more strongly correlated with WT. Spatial trends in TP and TN concentrations corresponded to observed nutrient fluxes from adjoining rivers in densely populated areas, demonstrating the influence of watershed pollutant loads on lake water quality. Among important questions to be answered is whether wind-driven resuspension of existing nutrients in sediments in this shallow (cyanobacteria blooms to begin. This study identifies other questions, data gaps, and research needs, and provides a foundation for improving lake management strategies.

  15. Ecological, biogeochemical and salinity changes in coastal lakes and wetlands over the last 200 years

    Science.gov (United States)

    Roberts, Lucy; Holmes, Jonathan; Horne, David

    2016-04-01

    Shallow lakes provide extensive ecosystem services and are ecologically important aquatic resources supporting a diverse flora and fauna. In marginal-marine areas, where such lakes are subjected to the multiple pressures of coastal erosion, sea level rise, increasing sea surface temperature and increasing frequency and intensity of storm surges, environments are complex and unstable. They are characterised by physico-chemical variations due to climatic (precipitation/evaporation cycles) and dynamic factors (tides, currents, freshwater drainage and sea level changes). Combined with human activity in the catchment these processes can alter the salinity, habitat and ecology of coastal fresh- to brackish water ecosystems. In this study the chemical and biological stability of coastal lakes forming the Upper Thurne catchment in the NE of the Norfolk Broads, East Anglia, UK are seriously threatened by long-term changes in salinity resulting from storm surges, complex hydrogeology and anthropogenic activity in the catchment. Future management decisions depend on a sound understanding of the potential ecological impacts, but such understanding is limited by short-term observations and measurements. This research uses palaeolimnological approaches, which can be validated and calibrated with historical records, to reconstruct changes in the aquatic environment on a longer time scale than can be achieved by observations alone. Here, salinity is quantitatively reconstructed using the trace-element geochemistry (Sr/Ca and Mg/Ca) of low Mg-calcite shells of Ostracoda (microscopic bivalved crustaceans) and macrophyte and macroinvertebrate macrofossil remains are used as a proxy to assess ecological change in response to variations in salinity. δ13C values of Cladocera (which are potentially outcompeted by the mysid Neomysis integer with increasing salinity and eutrophication) can be used to reconstruct carbon cycling and energy pathways in lake food webs, which alongside

  16. Deteriorating water clarity in shallow waters: Evidence from long term MODIS and in-situ observations

    Science.gov (United States)

    Shi, Kun; Zhang, Yunlin; Zhu, Guangwei; Qin, Boqiang; Pan, Delu

    2018-06-01

    Water clarity (Secchi disk depth: SDD), as a proxy of water transparency, provides important information on the light availability to the water or lake ecosystem. Shallow lakes have been experienced dramatic environmental and climatic change. This study demonstrated using combination of long-term MODIS and in-situ measurements to track the dynamics of SDD with these environmental and climate changes in shallow water environments. We selected a typical turbid shallow Lake Taihu as our case study. Based on MODIS-Aqua data, an empirical model for estimating SDD was developed and validated. Subsequently, we employed the proposed model to derive the spatial and temporal SDD distribution patterns of Lake Taihu from 2003 to 2015. Combining MODIS-derived SDD time series of 2003-2015 and long-term in-situ SDD observations dated back to 1993, we elucidated SDD long-term variation trends and driving mechanism. Deteriorating water clarity from the long-term SDD observations indicated that Lake Taihu became more and more turbid and water quality was decreasing. Increasing in cyanobacterial bloom area, as a result of decreasing in wind speed and eutrophication, may partially be responsible for the decreasing trend. A predicted future decrease in the wind speed in Lake Taihu region could enhance the formation of cyanobacterial blooms and consequently lead to a further decrease in water clarity. This study suggested that coupling remote sensing monitoring and long-term in-situ observations could provide robust evidence and new insights to elucidate long-term dynamics in aquatic ecosystem evolution.

  17. Spatial and temporal variability in midge (Nematocera) assemblages in shallow Finnish lakes (60-70 deg N) : community-based modelling of past environmental change

    Energy Technology Data Exchange (ETDEWEB)

    Luoto, T.

    2010-07-01

    Multi- and intralake datasets of fossil midge assemblages in surface sediments of small shallow lakes in Finland were studied to determine the most important environmental factors explaining trends in midge distribution and abundance. The aim was to develop palaeoenvironmental calibration models for the most important environmental variables for the purpose of reconstructing past environmental conditions. The developed models were applied to three high-resolution fossil midge stratigraphies from southern and eastern Finland to interpret environmental variability over the past 2000 years, with special focus on the Medieval Climate Anomaly (MCA), the Little Ice Age (LIA) and recent anthropogenic changes. The midge-based results were compared with physical properties of the sediment, historical evidence and environmental reconstructions based on diatoms (Bacillariophyta), cladocerans (Crustacea: Cladocera) and tree rings. The results showed that the most important environmental factor controlling midge distribution and abundance along a latitudinal gradient in Finland was the mean July air temperature (TJul). However, when the dataset was environmentally screened to include only pristine lakes, water depth at the sampling site became more important. Furthermore, when the dataset was geographically scaled to southern Finland, hypolimnetic oxygen conditions became the dominant environmental factor. The results from an intralake dataset from eastern Finland showed that the most important environmental factors controlling midge distribution within a lake basin were river contribution, water depth and submerged vegetation patterns. In addition, the results of the intralake dataset showed that the fossil midge assemblages represent fauna that lived in close proximity to the sampling sites, thus enabling the exploration of within-lake gradients in midge assemblages. Importantly, this within-lake heterogeneity in midge assemblages may have effects on midge-based temperature

  18. The interaction of large amplitude internal seiches with a shallow sloping lakebed: observations of benthic turbulence in Lake Simcoe, Ontario, Canada.

    Directory of Open Access Journals (Sweden)

    Remo Cossu

    Full Text Available Observations of the interactions of large amplitude internal seiches with the sloping boundary of Lake Simcoe, Canada show a pronounced asymmetry between up- and downwelling. Data were obtained during a 42-day period in late summer with an ADCP and an array of four thermistor chains located in a 5 km line at the depths where the thermocline intersects the shallow slope of the lakebed. The thermocline is located at depths of 12-14 m during the strongly stratified period of late summer. During periods of strong westerly winds the thermocline is deflected as much as 8 m vertically and interacts directly with the lakebed at depth between 14-18 m. When the thermocline was rising at the boundary, the stratification resembles a turbulent bore that propagates up the sloping lakebed with a speed of 0.05-0.15 m s(-1 and a Froude number close to unity. There were strong temperature overturns associated with the abrupt changes in temperature across the bore. Based on the size of overturns in the near bed stratification, we show that the inferred turbulent diffusivity varies by up to two orders of magnitude between up- and downwellings. When the thermocline was rising, estimates of turbulent diffusivity were high with KZ ∼10(-4 m(2s(-1, whereas during downwelling events the near-bed stratification was greatly increased and the turbulence was reduced. This asymmetry is consistent with previous field observations and underlines the importance of shear-induced convection in benthic bottom boundary layers of stratified lakes.

  19. Water-quality and bottom-material characteristics of Cross Lake, Caddo Parish, Louisiana, 1997-99

    Science.gov (United States)

    McGee, Benton D.

    2004-01-01

    Cross Lake is a shallow, monomictic lake that was formed in 1926 by the impoundment of Cross Bayou. The lake is the primary drinking-water supply for the City of Shreveport, Louisiana. In recent years, the lakeshore has become increasinginly urbanized. In addition, the land use of the watershed contributing runoff to Cross Lake has changed. Changes in land use and urbanization could affect the water chemistry and biology of the Lake. Water-quality data were collected at 10 sites on Cross Lake from February 1997 to February 1999. Water-column and bottom-material samples were collected. The water-column samples were collected at least four times per year. These samples included physical and chemical-related properties such as water temperature, dissolved oxygen, pH, and specific conductance; selected major inorganic ions; nutrients; minor elements; organic chemical constituents; and bacteria. Suspended-sediment samples were collected seven times during the sampling period. The bottom-material samples, which were collected once during the sampling period, were analyzed for selected minor elements and inorganic carbon. Aside from the nutrient-enriched condition of Cross Lake, the overall water-quality of Cross Lake is good. No primary Federal or State water-quality criteria were exceeded by any of the water-quality constituents analyzed for this report. Concentrations of major inorganic constituents, except iron and manganese, were low. Water from the lake is a sodium-bicarbonate type and is soft. Minor elements and organic compounds were present in low concentrations, many below detection limits. Nitrogen and phosphorus were the nutrients occurring in the highest concentrations. Nutrients were evenly distributed across the lake with no particular water-quality site indicating consistently higher or lower nutrient concentrations. No water samples analyzed for nitrate exceeded the U.S. Environmental Protection Agency's Maximum Contaminant Level of 10 milligrams per

  20. Submerged macrophytes shape the abundance and diversity of bacterial denitrifiers in bacterioplankton and epiphyton in the Shallow Fresh Lake Taihu, China.

    Science.gov (United States)

    Fan, Zhou; Han, Rui-Ming; Ma, Jie; Wang, Guo-Xiang

    2016-07-01

    nirK and nirS genes are important functional genes involved in the denitrification pathway. Recent studies about these two denitrifying genes are focusing on sediment and wastewater microbe. In this study, we conducted a comparative analysis of the abundance and diversity of denitrifiers in the epiphyton of submerged macrophytes Potamogeton malaianus and Ceratophyllum demersum as well as in bacterioplankton in the shallow fresh lake Taihu, China. Results showed that nirK and nirS genes had significant different niches in epiphyton and bacterioplankton. Bacterioplankton showed greater abundance of nirK gene in terms of copy numbers and lower abundance of nirS gene. Significant difference in the abundance of nirK and nirS genes also existed between the epiphyton from different submerged macrophytes. Similar community diversity yet different community abundance was observed between epiphytic bacteria and bacterioplankton. No apparent seasonal variation was found either in epiphytic bacteria or bacterioplankton; however, environmental parameters seemed to have direct relevancy with nirK and nirS genes. Our study suggested that submerged macrophytes have greater influence than seasonal parameters in shaping the presence and abundance of bacterial denitrifiers. Further investigation needs to focus on the potential contact and relative contribution between denitrifiers and environmental factors.

  1. In situ high-resolution evaluation of labile arsenic and mercury in sediment of a large shallow lake

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Chao; Yao, Yu; Wang, Peifang; Hou, Jun; Qian, Jin; Yuan, Ye; Fan, Xiulei

    2016-01-15

    The precise evaluation of arsenic (As) and mercury (Hg) bioavailability in sediment is crucial to controlling As and Hg contamination, but traditional ex situ measurements hamper comprehensive analysis of labile As and Hg in sediment. In this study, we characterized in situ labile As and Hg in sediment of Lake Hongze using the zirconium (Zr) oxide diffusive gradients in thin films (DGT) technique and 3-mercaptopropyl functionalized silica gel DGT, respectively. The concentrations of DGT-labile As and Hg in the sediment profiles were found to exhibit considerable variation, ranging from 0.15 to 4.15 μg L{sup −1} for As and from 0.04 to 1.35 μg L{sup −1} for Hg. As and Hg flux values, calculated based on the concentration gradients measured from the DGT profiles for both the overlying water and sediment close to the sediment–water interface, were used to determine the contamination status of As and Hg. Flux values of As and Hg were between − 0.066 and 0.067 ng cm{sup −2} d{sup −1} and between − 0.0187 and 0.0181 ng cm{sup −2} d{sup −1}, respectively. The GNU's Not Unix R (GNU R) programming language was used to identify outliers of As and Hg at various depths at the sampling sites. The results indicate that the sites with the most outliers were all located in the regions that were seriously affected by contaminants from the Huai River. The DGT-labile As and Hg concentrations in the 0–30 mm layer were found to be significantly correlated with concentrations of labile As and Hg, total dissolved As and Hg, and total As and Hg in the overlying water, as indicated by ex situ measurements. Results show that DGT is a reliable and high-resolution technique that can be used for in situ monitoring of the labile fractions of As and Hg in sediment in fresh water bodies. - Graphical abstract: The principle of DGT is based on the diffusion of dissolved species through a well-defined gel and subsequent accumulation on an ion-exchange resin. A diffusion

  2. In situ high-resolution evaluation of labile arsenic and mercury in sediment of a large shallow lake

    International Nuclear Information System (INIS)

    Wang, Chao; Yao, Yu; Wang, Peifang; Hou, Jun; Qian, Jin; Yuan, Ye; Fan, Xiulei

    2016-01-01

    The precise evaluation of arsenic (As) and mercury (Hg) bioavailability in sediment is crucial to controlling As and Hg contamination, but traditional ex situ measurements hamper comprehensive analysis of labile As and Hg in sediment. In this study, we characterized in situ labile As and Hg in sediment of Lake Hongze using the zirconium (Zr) oxide diffusive gradients in thin films (DGT) technique and 3-mercaptopropyl functionalized silica gel DGT, respectively. The concentrations of DGT-labile As and Hg in the sediment profiles were found to exhibit considerable variation, ranging from 0.15 to 4.15 μg L −1 for As and from 0.04 to 1.35 μg L −1 for Hg. As and Hg flux values, calculated based on the concentration gradients measured from the DGT profiles for both the overlying water and sediment close to the sediment–water interface, were used to determine the contamination status of As and Hg. Flux values of As and Hg were between − 0.066 and 0.067 ng cm −2 d −1 and between − 0.0187 and 0.0181 ng cm −2 d −1 , respectively. The GNU's Not Unix R (GNU R) programming language was used to identify outliers of As and Hg at various depths at the sampling sites. The results indicate that the sites with the most outliers were all located in the regions that were seriously affected by contaminants from the Huai River. The DGT-labile As and Hg concentrations in the 0–30 mm layer were found to be significantly correlated with concentrations of labile As and Hg, total dissolved As and Hg, and total As and Hg in the overlying water, as indicated by ex situ measurements. Results show that DGT is a reliable and high-resolution technique that can be used for in situ monitoring of the labile fractions of As and Hg in sediment in fresh water bodies. - Graphical abstract: The principle of DGT is based on the diffusion of dissolved species through a well-defined gel and subsequent accumulation on an ion-exchange resin. A diffusion gel and a filter membrane (to

  3. Cogs in the endless machine: Lakes, climate change and nutrient cycles: A review

    Energy Technology Data Exchange (ETDEWEB)

    Moss, Brian, E-mail: brmoss@liverpool.ac.uk

    2012-09-15

    Lakes have, rather grandly, been described as sentinels, integrators and regulators of climate change (). Lakes are also part of the continuum of the water cycle, cogs in a machine that processes water and elements dissolved and suspended in myriad forms. Assessing the changes in the functioning of the cogs and the machine with respect to these substances as climate changes is clearly important, but difficult. Many other human-induced influences, not least eutrophication, that impact on catchment areas and consequently on lakes, have generally complicated the recording of recent change in sediment records and modern sets of data. The least confounded evidence comes from remote lakes in mountain and polar regions and suggests effects of warming that include mobilisation of ions and increased amounts of phosphorus. A cottage industry has arisen in deduction and prediction of the future effects of climate change on lakes, but the results are very general and precision is marred not only by confounding influences but by the complexity of the lake system and the infinite variety of possible future scenarios. A common conclusion, however, is that warming will increase the intensity of symptoms of eutrophication. Direct experimentation, though expensive and still unusual and confined to shallow lake and wetland systems is perhaps the most reliable approach. Results suggest increased symptoms of eutrophication, and changes in ecosystem structure, but in some respects are different from those deduced from comparisons along latitudinal gradients or by inference from knowledge of lake behaviour. Experiments have shown marked increases in community respiration compared with gross photosynthesis in mesocosm systems and it may be that the most significant churnings of these cogs in the earth-air-water machine will be in their influence on the carbon cycle, with possibly large positive feedback effects on warming. -- Highlights: Black-Right-Pointing-Pointer Climate change has had

  4. Are all temperate lakes eutrophying in a warmer world?

    Science.gov (United States)

    Paltsev, A.; Creed, I. F.

    2017-12-01

    Freshwater lakes are at risk of eutrophication due to climate change and intensification of human activities on the planet. In relatively undisturbed areas of the temperate forest biome, lakes are "sentinels" of the effects of rising temperatures. We hypothesise that rising temperatures are driving a shift from nutrient-poor oligotrophic states to nutrient-rich eutrophic states. To test this hypothesis, we examined a time series of satellite based chlorophyll-a (a proxy of algal biomass) of 12,000+ lakes over 30 years in the Canadian portion of the Laurentian Great Lakes basin. From the time series, non-stationary trends (detected by Mann-Kendall analysis) and stationary cycles (revealed through Morlet wavelet analysis) were removed, and the standard deviation (SD) of the remaining residuals was used as an indicator of lake stability. Four classes of lake stability were identified: (1) stable (SD is consistently low); (2) destabilizing (SD increases over time); (3) unstable (SD is consistently high); and (4) stabilizing lakes (SD decreases over time). Stable lakes were either oligotrophic or eutrophic indicating the presence of two stable states in the region. Destabilizing lakes were shifting from oligotrophic to lakes with a higher trophic status (indicating eutrophication), unstable lakes were mostly mesotrophic, and stabilizing lakes were shifting from eutrophic to the lakes with lower trophic status (indicating oligotrophication). In contrast to common expectations, while many lakes (2142) were shifting from oligotrophic to eutrophic states, more lakes (3199) were showing the opposite trend and shifting from eutrophic to oligotrophic states. This finding reveals a complexity of lake responses to rising temperatures and the need to improve understanding of why some lakes shift while others do not. Future work is focused on exploring the interactive effects of global, regional, and local drivers of lake trophic states.

  5. Eutrophication Modeling Using Variable Chlorophyll Approach

    International Nuclear Information System (INIS)

    Abdolabadi, H.; Sarang, A.; Ardestani, M.; Mahjoobi, E.

    2016-01-01

    In this study, eutrophication was investigated in Lake Ontario to identify the interactions among effective drivers. The complexity of such phenomenon was modeled using a system dynamics approach based on a consideration of constant and variable stoichiometric ratios