Summer Water Levels Research Articles

Deciphering the functional and structural complexity of the Solar Lake flat mat microbial benthic communities.

Fifty-five years ago, the extremophilic "Solar Lake" was discovered on the Red Sea shores, garnering microbiologists' interest worldwide from the 1970s to 1990s. Nevertheless, research on the lake paused at the turn of the millennium. In our study, we revisited the Solar Lake benthic community using a genome-centric approach and described the distinct microbial communities in the exposed versus shallow-water mat unveiling microbial zonation in the benthic communities surrounding the Solar Lake. Our findings highlighted the unique structural and functional adaptations employed by these microbial mat communities. Moreover, we report new methanogens and phototrophs, including an intriguing methanogen from the Archaeoglobales family. We describe how the Solar Lake's flat mat microbial community adapts to stressors like oxygen intrusion and drought due to summer water level changes, which provides insights into the genomic strategies of microbial communities to cope with altered and extreme environmental conditions.

Establishing peat-forming plant communities: A comparison of wetland reclamation methods in Alberta's oil sands region.

The Sandhill Wetland (SW) and Nikanotee Fen (NF) are two wetland research projects designed to test the viability of peatland reclamation in the Alberta oil sands post-mining landscape. To identify effective approaches for establishing peat-forming vegetation in reclaimed wetlands, we evaluated how plant introduction approaches and water level gradients influence species distribution, plant community development, and the establishment of bryophyte and peatland species richness and cover. Plant introduction approaches included seeding with a Carex aquatilis-dominated seed mix, planting C. aquatilis and Juncus balticus seedlings, and spreading a harvested moss layer transfer. Establishment was assessed 6 years after the introduction at SW and 5 years after the introduction at NF. In total, 51 species were introduced to the reclaimed wetlands, and 122 species were observed after 5 and 6 years. The most abundant species in both reclaimed wetlands was C. aquatilis, which produced dense canopies and occupied the largest water level range of observed plants. Introducing C. aquatilis also helped to exclude marsh plants such as Typha latifolia that has little to no peat accumulation potential. Juncus balticus persisted where the water table was lower and encouraged the formation of a diverse peatland community and facilitated bryophyte establishment. Various bryophytes colonized suitable areas, but the moss layer transfer increased the cover of desirable peat-forming mosses. Communities with the highest bryophyte and peatland species richness and cover (averaging 9 and 14 species, and 50%-160% cover respectively) occurred where the summer water level was between -10 and -40 cm. Outside this water level range, a marsh community of Typha latifolia dominated in standing water and a wet meadow upland community of Calamagrostis canadensis and woody species established where the water table was deeper. Overall, the two wetland reclamation projects demonstrated that establishing peat-forming vascular plants and bryophytes is possible, and community formation is dependent upon water level and plant introduction approaches. Future projects should aim to create microtopography with water tables within 40 cm of the surface and introduce vascular plants such as J. balticus that facilitate bryophyte establishment and support the development of a diverse peatland plant community.

Spatiotemporal variability of pH in coastal waters of New Brunswick (Canada) and potential consequences for oyster aquaculture

There is a void in the knowledge of the acidification status of Eastern Canada's coastal waters. This knowledge is crucial to evaluating the threats posed to marine life, particularly oyster farming, a flagship of New Brunswick seafood production. In this study, we measured the temporal variability of pH and related environmental parameters in three bays of Northeastern New Brunswick. We also evaluated the potential impact of the observed pH levels on the Eastern oyster (Crassostrea virginica Gmelin, 1791), based on the available literature on this species’ sensitivity to acidification. We investigated the presence of inherent cycles of pH with the Fourier transform and the spectral filtering technique. Our results show that pH is highly variable in the studied area, with values ranging from 7.31 to 8.90. A seasonal effect was apparent, as the pH fluctuations were set at the lowest level in winter when the cover of ice and snow on the bay was present. The spectral analysis revealed a clear semidiurnal tidal pattern of pH, this variable being inversely related to the water level in summer and directly related to it in winter. The spectral subtraction of all the tidal components allowed the detection of a circadian rhythm that was not in pace with the alternation between day and night but rather slowly drifted so that the pH troughs occurred at night during the full moon period. Short periodicities of circa 8 and 6 h also existed in two of the three bays. Based on current knowledge of C. virginica’s sensitivity to acidification, this species’ recruitment, growth, and survival are unlikely to be impacted by the present pH levels in the studied area. However, further acidification might overcome the resilience of C. virginica, especially that of the larvae that are produced during the winter in commercial hatcheries.

Characterizing water body changes in Poyang lake using multi-source remote sensing data

This study analyzed changes in water body characteristics of Poyang Lake using remote sensing data (Sentinel-2, Sentinel-3 and ICESat-2) and machine learning methods (random forest, support vector machine and classification and regression tree). Furthermore, the relationship between the water area and water level was analyzed. The main findings are as follows: (1) the peak water range in 2016 and 2017 was significantly larger than in 2018 and 2019. The water extent is large in the summer (maximum ∼2650 km2 in July 2016) and small in the winter (minimum ∼600 km2 in February 2017); (2) the spatial scale of water level fluctuated widely, while the temporal scale showed seasonal characteristics. Water level showed seasonal characteristics, with the higher water levels in summer (20.5 m in July 2016) and lower water levels in winter (8.8 m in October 2019); and (3) there was a strong agreement between water level and extent from 2016 to 2019, for which two models fitted by the logarithmic method had a small root mean square error (R12 = 0.67, RMSE1 = 9.02; R22 = 0.55; RMSE2 = 4.88).

Vascular Plant Succession on an Exposed Fluvial Delta Plain After a Permanent Lake Water Level Drawdown. A 33-Year Time Course

A permanent lake water level drawdown initiates a vegetation succession on exposed sediments. This study aims to quantify long-term vascular plant changes on the sediments in time (number of years after drawdown) and space (elevation above the new water level). Shortly after a 1.4 m permanent drawdown of Myrkdalen lake, W Norway, a 40 m long transect running from the original lowermost vegetation toward the new water level was established. Species cover percentages in the 2 m2 study plots were determined by visual estimates and data sampling was performed from 1988 until 2020; in total, 19 times. During the study period both mean richness and plant percentage cover varied significantly in relation to space and time. Carex vesicaria and Phalaris arundinacea increased gradually especially in the lower parts. The successional changes as quantified by a DCA ordination showed rapid changes during the first 15-20 years, but later the vegetation appeared to be more stabilized. Elevation explained the mean floristic variation in a linear fashion while a quadratic model better explained the variation in relation to time. Variation in summer and June water level explained a small part of the succession change during the study period.

Genotoxic risk assessment of solar UV radiation in tadpoles from Brazilian wetlands

Solar ultraviolet (UV) radiation is an environmental genotoxic factor linked to amphibian decline. Here we assessed the genotoxic risk of UVB and UVA exposure for tadpoles from open ponds in southern Brazil, a mid-latitude region influenced by stratospheric ozone depletion. Daily UV doses were measured on the surface of a pond in Taim Ecological Station (TAIM; 32°49’24’’S; 52°38’31’’W) on a cloudless summer day to predict the worst-case scenario for UV-induced DNA damage. Pond descriptors were related to the use of microhabitats by Boana pulchella tadpoles in two ponds over the climate seasons of 2013 and 2014. Our results indicate that shaded microhabitats were more frequent than unshaded ones in autumn, winter, and spring but not in summer. Hence, the penetration of UV radiation into the water of unshaded microhabitats was evaluated through laboratory experiments with artificial UV sources and pond water samples. Physical and biological sensors were applied in the experiments to measure the incident UV radiation and its genotoxic action. By integrating field and laboratory data, we demonstrate that low doses of biologically effective UV radiation reached the tadpoles in autumn, winter, spring, and early summer due to a high proportion of shaded microhabitats and a high concentration of solids in unshaded microhabitats. However, the relative reduction of shaded microhabitats jointly with a declining water level in late summer may have exposed tadpoles to high UV doses. Our experiments also indicate that solar UVB radiation, but not UVA, is primarily responsible for the induction of DNA pyrimidine dimers in organisms living under the surface of aquatic ecosystems. The present work highlights the determinant role of wetland descriptors for minimizing the genotoxic potential of UV radiation and its consequences for amphibians.

Prevalence and risk assessment of microplastics in the Nile Delta estuaries: “The Plastic Nile” revisited

Recent research is directed toward studying plastic pollution in rivers, and estuaries due to the importance of freshwater bodies in all aspects of life. The river deltas and estuaries are interesting for studying the flux of plastics into the oceans. The Nile River has been identified as a hot spot of plastic litter flux in the eastern Mediterranean basin. In addition, it was nicknamed “Plastic Nile”, yet this major river is largely unexplored with a lack of field measurements and adequate surveys. The current study was based on bridging this scientific gap. Three trips were conducted, covering 30 km in the Rosetta branch and 23 km in the Damietta branch, during the high water level in summer 2021, and 10 km off the inlet of Lake Burullus, in spring 2021. Microplastics in surface water ranged from 761 ± 319 to 1718 ± 1008 MPs/m3, and from 167 ± 137 to 1630 ± 1303 MPs/kg of dry sediments. Land use/ land cover mapping using Sentinel-2 images showed several sources of pollution that contribute to plastic contamination in the study area. Thermal analysis indicated seven plastic polymers; including, PE, PP, PET, PEVA, and PTFE, using discarded plastic products as reference materials. Microplastics were composed of colored and glossy fragments of sizes <500 μm, originating from land-based sources. Pollution load, polymer risk assessment, and ecological risk indices were calculated. Based on field observations macro-plastics were retained within the extensive network of infrastructure and dam systems. 80–106 billion MPs/year were estimated to flux from the Nile estuaries into the Mediterranean Sea. The current situation urges the development of binding plans to reduce plastic waste in the Nile Delta, as well as setting environmental monitoring points along the Deltaic coast.

Factors Determining the Abundance of Red Swamp Crayfish (Procambarus clarkii) in a Large Lake Connected to the Yangzte River

Invasive species and habitat degradation are the main reasons for freshwater biodiversity loss. Reports on the habitat degradation and invasion ecology of Red Swamp crayfish (Procambarus clarkii) are few, although it is one of the most devastating invasive species in freshwater ecosystems. Based on a three-year investigation during 2017–2019 in West Dongting Lake, this study used Principal Component Analysis (PCA), Generalized Linear Model (GLM) and Bayesian model to analyze the relationships of P. clarkii stocks and environment factors in natural and modified wetlands. The results showed that the abundance of P. clarkii was positively correlated with total nitrogen, total phosphorus, water temperature, pH, water depth, and water transparency; while it was negatively correlated with dissolved oxygen and redox potential. The difference between P. clarkii stocks in natural and modified wetlands was nonsignificant. The P. clarkii stock decreased yearly, as levels in both 2018 and 2019 were significantly lower than in 2017. We concluded that inter-annual variation of the hydrological regime plays an important role in P. clarkii dynamics, and thus it is of great importance to ensure that the water level and flow velocity in summer to control the invasive P. clarkii.

Species diversity, spatial distribution and protection strategies of wintering waterbirds after extreme summer flood in Lake Poyang

鄱阳湖是我国最大的淡水湖，也是具有国际意义的候鸟越冬地. 近年来，鄱阳湖水文情势异常使得候鸟越冬环境更加复杂. 本文以2020年鄱阳湖出现夏季极端水位为背景，基于2019和2020年鄱阳湖越冬水鸟同步调查数据，探讨了夏季极端水位对越冬水鸟丰富度和空间分布的影响. 研究结果表明：夏季极端水位条件下鄱阳湖越冬水鸟的总数量、群落结构和优势物种组成相对稳定，水鸟数量由597307只下降至572358只，主要是鸭科、鸥科、鹳科、鸬鹚科和鹮科鸟类数量明显下降；食块茎、食种子和食鱼集团水鸟数量均有所下降. 水鸟的整体空间分布格局变化不大，主要栖息地仍为鄱阳湖保护区和上饶湿地的碟形湖及人控湖汊，越冬水鸟向人工湿地扩散加剧. 2019年在人工湿地主要记录到灰鹤926只、白鹤3只；2020年则记录到白鹤2215只、灰鹤7294只、白头鹤88只、白枕鹤378只、豆雁550只、鸿雁3100只、灰雁3200只和小天鹅1543只. 2020年冬季人工湿地中的越冬水鸟数量比2019年增加显著. 鄱阳湖夏季极端水位导致沉水植物群落崩溃，造成植食性水鸟在天然湿地中的越冬食物短缺，从而导致种群空间分布格局出现明显变化，这也是鹤类和雁类水鸟前往人工湿地觅食的主要原因. 因此，在夏季洪水频发的背景下加强人工湿地管理，是当前解决越冬水鸟天然湿地食物资源短缺的重要措施.;Lake Poyang is the largest freshwater lake in China and has been an important wintering ground for migratory birds. In recent years, the abnormal hydrological regime of Lake Poyang deteriorated the quality of this wintering ground for migratory birds. In summer of 2020, Lake Poyang experienced extreme water level, which maybe affect the waterbird community structure and waterbird distribution. We compared the wintering waterbird species diversity, abundance and spatial distribution between winter of 2019 and 2020 to understand the impact of extreme water level on wintering waterbirds. The results showed that the total number, community structure and dominant species composition of wintering waterbirds were relatively stable after extreme summer water level. The total number of waterbirds decreased from 597307 to 572358, among which the number of Anatidae, Laridae, Ciconiidae, Phalacrocoracidae and Threskiornithidae obviously decreased. The abundances of tuber eaters, seed eaters and fish eaters were declined. The overall spatial distribution pattern of waterbirds showed little change. Waterbirds mainly inhabited the sub-lakes and controlled lake branches in the Lake Poyang National Nature Reserve and Shangrao wetland. However, waterbirds spread more severely from Lake Poyang nature wetlands to artificial wetlands nearby Lake Poyang. In 2019, 926 common cranes and 3 Siberian cranes were recorded in rice paddies and lotus ponds; In 2020, 2215 Siberian cranes, 7294 common cranes, 88 hooded cranes, 378 white-napped cranes, 550 bean geese, 3100 swan geese, 3200 greylag geese and 1543 tundra swans occurred in these artificial wetlands. The wintering waterbirds in artificial wetlands in winter of 2020 was significantly more abundant than that in winter of 2019. The extreme water level in summer led to the collapse of submerged plant community, resulting in the shortage of wintering food for herbivorous waterbirds in the natural wetlands, which drove cranes and geese dispersed into the artificial wetlands. Therefore, it is necessary to strengthen the management of artificial wetlands under the condition of frequently higher flood in Lake Poyang for wintering waterbirds conservation.

Environmental flow assessment in a lake‐marsh system with reverse seasonal hydrological patterns

AbstractEnvironmental flow (e‐flow) assessment is essential for the ecological protection and restoration of lake‐marsh systems. Previous studies on e‐flow assessment for lake‐marsh systems focused on lake‐marsh systems with natural seasonal hydrological patterns (i.e., low water level in winter and high water level in summer). However, they have not considered lake‐marsh systems with reverse seasonal hydrological patterns (i.e., high water level in winter and low water level in summer). The reverse seasonal hydrological patterns impose seriously negative impacts on waterbirds, because the hydrological patterns could lead to limited plant germination in spring and massive plant death in summer, leaving few plants available as food for waterbirds in winter, and could consequently reduce the sheltering and forageable areas for waterbirds. This study took Hongze Lake Wetland National Nature Reserve in China as the study area. Based on the habitat requirements of waterbirds, the sheltering and forageable areas for waterbirds under different water‐depth and aquatic plant distribution scenarios were calculated. By exploring the impacts of reverse seasonal hydrological processes on waterbird habitats, we determined the necessary e‐flows for lake‐marsh systems with reverse seasonal hydrological patterns to meet the needs of waterbird habitat. The results showed that the water level of Hongze Lake should be controlled to 13.0–13.1 m in March, 12.5–12.6 m in July, and 12.9–13.0 m in October, which can meet the needs of waterbirds for both shelter and foraging.

Long Term Aquatic Vegetation Dynamics in Longgan Lake Using Landsat Time Series and Their Responses to Water Level Fluctuation

Aquatic vegetation in shallow freshwater lakes are severely degraded worldwide, even though they are essential for inland ecosystem services. Detailed information about the long term variability of aquatic plants can help investigate the potential driving mechanisms and help mitigate the degradation. In this paper, based on Google Earth Engine cloud-computing platform, we made use of a 33-year (1987–2019) retrospective archive of moderate resolution Landsat TM, ETM + and OLI satellite images to estimate the extent changes in aquatic vegetation in Longgan Lake from Middle Yangtze River Basin in China using the modified enhanced vegetation index, including emerged, floating-leaved and floating macrophytes. The analysis of the long term dynamics of aquatic vegetation showed that aquatic vegetation were mainly distributed in the western part of the lake, where lake bottom elevation ranged from 11 to 12 m, with average water depth of less than 1 m in spring. The vegetation area variation for the 33-year period were divided into six stages. In years with heavy precipitation, the vegetation area decreased sharply. In the following years, the area normally restored. Aquatic vegetation area had a significant negative correlation with the spring water level and summer water level. The results showed that aquatic vegetation was negatively affected when water depth exceeded 2.5 m in May and 5 m in summer. It is recommended that water depth remain close to 1 m in spring and close to 3 m in summer for aquatic vegetation growth. Our study provide quantitative evidence that water-level fluctuations drive vegetation changes in Longgan Lake, and present a basis for sustainable lake restoration and management.

Functional Diversity of Riparian Woody Vegetation Is Less Affected by River Regulation in the Mediterranean Than Boreal Region.

River regulation may filter out riparian plants often resulting in reduced functional diversity, i.e., in the range of functions that organisms have in communities and ecosystems. There is, however, little empirical evidence about the magnitude of such reductions in different regions. We investigated the functional diversity patterns of riparian woody vegetation to streamflow regulation in boreal Sweden and Mediterranean Portugal using nine plant functional traits and field data from 109 sampling sites. We evaluated changes in mean plant functional traits as well as in indices of multidimensional functional traits, i.e., functional richness (FRic) and functional redundancy (FRed) within regions and between free-flowing and regulated river reaches. We found that regulation significantly reduced functional diversity in Sweden but not in Portugal. In Sweden, the increased magnitude of variations in water flow and water level in summer, the prolonged duration of extreme hydrological events, the increased frequency of high-water pulses, and the rate of change in water conditions were the likely main drivers of functional diversity change. Small riparian plant species with tiny leaves, poorly lignified stems, and shallow root systems were consistently associated with regulated sites in the boreal region. In Portugal, the similar functional diversity values for free-flowing and regulated rivers likely stem from the smaller streamflow alterations by regulation combined with the species legacy adaptations to the Mediterranean natural hydrological regimes. We conclude that streamflow regulation may reduce the functional diversity of riparian woody vegetation, but the magnitude of these effects will vary depending on the adaptations of the local flora and the patterns of streamflow disturbances. Our study provides insights into functional diversity patterns of riparian woody vegetation affected by regulation in contrasting biomes and encourages further studies of the functional diversity thresholds for maintaining ecosystems.

Responses of an emergent macrophyte, Zizania latifolia, to water-level changes in lakes with contrasting hydrological management

Twenty-four lakes associated with the Yangtze floodplain and Huaihe basin, China, with different degrees of disconnection from the river systems, exhibited managed hydrologies ranging from minimally fluctuating reservoir-like lakes, through intermittently fluctuating lakes to those with large, quasi-natural fluctuations in level. We hypothesized that annual water-level fluctuations limit growth and survival of the emergent macrophyte Zizania latifolia. We investigated adaptations to submergence and sought to define the tolerances of Z. latifolia to the amplitude and timing of water-level fluctuations in these types of lake, at different stages in its phenology and life cycle. Shoots from rhizome buds emerged in early spring and reached maximum extension with high water levels in summer. Z. latifolia did not occur in lakes with the highest amplitude (>5 m) of fluctuation. Height growth in lakes with low amplitude (reservoir-like) was smaller than in lakes with greater amplitude (intermittent to quasi-natural fluctuations), giving the appearance of ‘short’ and ‘tall’ phenotypes. Across all lakes, however, maximum height was linearly related to water depth in June and to annual amplitude of water level, indicating a continuous phenotypic response. Peak biomass was weakly affected by these environmental drivers. Field experiments showed that seedlings tolerated water depths of c. twice their height (0.6 m), and submergence rates similar to their maximum extension growth rate (2 cm.d−1). Sprouting of rhizome buds was unaffected by submergence to a depth of 0.4 m, but then declined with depth. This study reveals the effects of large-scale hydrological engineering on an emergent macrophyte of economic and conservation importance and informs the management of its populations under seasonally fluctuating water-level regimes.

Integrated model projections of climate change impacts on water-level dynamics in the large Poyang Lake (China)

Abstract This study outlines a framework for examining potential impacts of future climate change in Poyang Lake water levels using linked models. The catchment hydrological model (WATLAC) was used to simulate river runoffs from a baseline period (1986–2005) and near-future (2020–2035) climate scenarios based on eight global climate models (GCMs). Outputs from the hydrological model combined with the Yangtze River's effects were fed into a lake water-level model, developing in the back-propagation neural network. Model projections indicate that spring–summer water levels of Poyang Lake are expected to increase by 5–25%, and autumn–winter water levels are likely to be lower and decrease by 5–30%, relative to the baseline period. This amounts to higher lake water levels by as much as 2 m in flood seasons and lower water levels in dry seasons in the range of 0.1–1.3 m, indicating that the lake may be wet-get-wetter and dry-get-drier. The probability of occurrence for both the extreme high and low water levels may exhibit obviously increasing trends by up to 5% more than at present, indicating an increased risk in the severity of lake floods and droughts. Projected changes also include possible shifts in the timing and magnitude of the lake water levels.

Investigation of Legacy Methane Seepage into Freshwater Food Webs Using Novel Applications in Stoney Creek, New Brunswick

Legacy oil, gas, and coalfields in the Maritime region have emitted methane into the surrounding ecosystem for more than 100 years. Methane escaping from these legacy sites may have effects on the surrounding terrestrial and aquatic environments. I investigated whether methane could be detected entering streams via groundwater inputs in an area with abandoned and active oil and gas wells. Introduction of a foreign compound, such as methane, could act as an environmental stressor and could impact the local food web starting at the lowest trophic level. I predicted that if methane was entering freshwater streams and being incorporated into the food web, it would be evident in the stable isotopes of consumers and prey. Methane would have a distinct isotopic carbon signature and could be traced through the various biotic compartments. This project focuses on the novel application of using a small thermal imaging camera to help detect subsurface groundwater inputs into the stream for site selection. Using this temperature sensing technology, I found and selected 5 suspected groundwater sources flowing into the stream channel. I collected biofilm (e.g. bacteria, algae, diatoms) and benthic macroinvertebrate from both upstream and downstream of each suspected groundwater input site. With small streams and low summer water levels, I was unable to adequately sample the fish community. Stable isotope analysis of biofilm and benthic macroinvertebrates did not show obvious incorporation of methane into the food web, though some values were suspect. Additionally, I completed a diatom community assessment applying the Eastern Canadian Diatom Index (IDEC) as a measure of the biological integrity of streams and were able to show that the study sites in the Stoney Creek region are currently considered “slightly polluted”, with a few select locations bordering on “polluted”. Although these techniques and tools did show the incorporation of methane in the food web at Stoney Creek, the combination of inexpensive tools can be employed in the investigation of methane at other sites. This study serves as an exploration and application of tools and techniques that have not previously been applied in this context.

The impact of climate change on inland waterway transport: Effects of low water levels on the Mackenzie River

Potential impact of climate change on the inland waterway transport of the Mackenzie River Basin (MRB) have been investigated through simulations of the Hydrologiske Byrån avdeling för Vattenbalans (HBV) hydrological model, the HBV-light, for the baseline, 1974–2004, and future periods of 2041–2070 and 2071–2100 over the MRB driven by precipitation and air temperature data of Representative Concentration Pathways, RCP4.5 and RCP8.5 climate scenarios of 10 Global Climate Models statistically downscaled by the Pacific Climate Impacts Consortium using the Bias-Correction Spatial Disaggregation. The average onset of spring snowmelt between 2041 and 2100 is projected to occur up to two weeks earlier than the historical (1974–2004) climate. Projected warmer temperature and higher precipitation will lead to higher runoff for MRB in winter and spring, at the expense of decreased summer streamflow and water level at Fort Simpson and Arctic Red River stations partly because projected increase in evapotranspiration will offset the projected increase in precipitation. Under a warmer climate, navigation issues related to low water levels are expected to increase, e.g., under RCP8.5 at Arctic Red River station, the number of days the water level above 5 m is projected to decrease from 74 days in 1974–2000 to 42 days in the 2080s. The summer durations that water levels of MRB will be at or above 3, 4, and 5 m are projected to decrease by 2.8%–22.2%, 10.0%–34.5%, and 16.2%–43.4%, respectively, which mean navigation problems would increase because safe transit through MRB depends on its water levels.

Algal Diversity and Water Quality Assessment During Summer in Some Suburban Water Bodies of Lucknow, Uttar Pradesh

Freshwater algae can tolerate wide range of environmental stress and grow naturally in mixed communities. In the present study diversity of algae has been studied in some suburban water bodies near Lucknow, which revealed the occurrence of 32 genera and 40 taxa under four phyla - Cyanophyta, Chlorophyta, Bacillariophyta and Euglenophyta. It is observed that heavy anthropogenic activities and low water level in late summer resulted in accumulation of pollutants which affected the algal species composition. The polluted water with high conductivity and total dissolved solids (TDS) showed the dominance of Cyanophyta and Bacillariophyta whereas most of Chlorophyta and few Bacillariophyta were found in less polluted water with low conductivity and TDS. Taxa Centritractus belonophorus belonging to Xanthophyta is being reported for the first time from Uttar Pradesh. The study also recorded for the first time several algal taxa from these water bodies of Lucknow.

Algal Diversity and Water Quality Assessment During Summer in Some Suburban Water Bodies of Lucknow, Uttar Pradesh

Freshwater algae can tolerate wide range of environmental stress and grow naturally in mixed communities. In the present study diversity of algae has been studied in some suburban water bodies near Lucknow, which revealed the occurrence of 32 genera and 40 taxa under four phyla - Cyanophyta, Chlorophyta, Bacillariophyta and Euglenophyta. It is observed that heavy anthropogenic activities and low water level in late summer resulted in accumulation of pollutants which affected the algal species composition. The polluted water with high conductivity and total dissolved solids (TDS) showed the dominance of Cyanophyta and Bacillariophyta whereas most of Chlorophyta and few Bacillariophyta were found in less polluted water with low conductivity and TDS. Taxa Centritractus belonophorus belonging to Xanthophyta is being reported for the first time from Uttar Pradesh. The study also recorded for the first time several algal taxa from these water bodies of Lucknow.

Interactions of water levels with water quality, endemic waterbirds, and invasive species in a shallow, tropical pond

This study responds to a need for baseline physical and chemical data in shallow tropical water bodies. We investigated the degree to which water level fluctuations affected water quality and biota in a shallow tropical pond, Keālia Pond National Wildlife Refuge in Hawaii. We observed strong interactions among climate, water levels, salinity, DO, turbidity, waterbirds, fish, and invertebrates. Seasonal precipitation and air temperature patterns led to higher pond levels in winter and lower pond levels in summer. Low water levels in summer were associated with very high salinity and turbidity, and low DO. Endemic waterbirds were favored by lower water levels. Extremely low DO concentrations at minimum water levels caused fish die-offs, primarily non-native tilapia. The fish die-offs temporarily resulted in lower turbidities, clearer water, and a large increase in invertebrates, specifically a native rotifer but also a non-native chironomid midge. Nuisance emergences of midge only occurred in winters following summer fish die-offs but only if there was sufficient winter streamflow to lower salinity and create brackish conditions in the pond. The study results were used to assess restoration and management options to promote endemic waterbirds and other natives and suppress invasive species.

Abnormal increase of Mn and TP concentrations in a temperate reservoir during fall overturn due to drought-induced drawdown

Due to global warming, some regions of Earth may face frequent and severe droughts in the future, leading to the deterioration of surface water quality. In this study, we investigated the effects of drought-induced drawdown on the water quality of the Zhoucun Reservoir, Shandong Province, East China, during the fall overturn. Field surveys were conducted during stratification (April–November) over three standard years 2012, 2013, and 2014, and over the El Niño event of 2015. Temporal and vertical variations of the physical and chemical indexes were investigated during monitoring. Results show that after the formation of stratification, the hypolimnion rapidly shifted to anaerobic conditions, with the accumulation of pollutants such as manganese (Mn) and total phosphorous (TP). Due to the extreme El Niño event in 2015, both the upper and lower metalimnion limits moved down along with the water level in summer, which resulted in the transfer of hypolimnion water to the metalimnion. In summer 2015, large amounts of pollutants were measured in the metalimnion: a phenomenon that did not occur at the same period of the standard years. At the beginning of the overturn in 2015, the water quality of the whole reservoir deteriorated when the metalimnion water shifted to the epilimnion. Mn and TP concentrations in the epilimnion reached 0.202mg/L and 0.086mg/L, respectively, which are significantly higher than those in the standard years. Although the tributary rivers entered the epilimnion of the reservoir during the overturn, Mn and TP concentrations of the inflow were only of 0.049–0.072mg/L and 0.033–0.047mg/L, respectively, indicating that these rivers were not the source of the high TP and high Mn concentrations in the epilimnion. Hence, we conclude that more attention should be paid to the metalimnion position and the vertical distribution of pollutants when studying lakes and reservoirs experiencing droughts.