Shallow Turbid Lake Research Articles

Quantitative assessment of decadal water temperature changes in Lake Kasumigaura, a shallow turbid lake, using a one-dimensional model

To assess the decadal water temperature (WT) changes observed at the center of Lake Kasumigaura, a shallow turbid lake in Japan, we constructed a prediction model for WT. The thermal interactions among air, water, and sediment were simulated by a one-dimensional differential equation using hourly observations of meteorological and limnological parameters. The validated model showed good performance (i.e., <1 °C RMSE for the daily averaged WT) for 2012, 2013, and 2015, respectively, in both upper and lower water layers, which were attained by incorporating a physical sub-model regarding the surface water temperature (surface WT). The good description of seasonal, daily, and hourly changes in surface WT obtained with the sub-model was confirmed by the observed and simulated time series. We then quantified and evaluated the trends of the meteorological and limnological parameters influencing WT changes from 1979 to 2015 based on their effects on WT by using the prediction model with the increases in air temperature (AT), solar radiation (SR), wind velocity (WV), and turbidity during that period; then, WT in the former period (1979) was predicted according to the trends and compared with the measured WT. The observed WT changes during the period were quantitatively explained by the compound effects of the parameters' changes, i.e., the AT and SR raising the WT, and the WV and turbidity lowering the WT.

Quantitative Assessment of Decadal Water Temperature Changes in Lake Kasumigaura, a Shallow Turbid Lake, Using a One-Dimensional Model

Quantitative Assessment of Decadal Water Temperature Changes in Lake Kasumigaura, a Shallow Turbid Lake, Using a One-Dimensional Model

A Floating Optical Buoy (FOBY) for Direct Measurement of Water‐Leaving Radiance Based on the Skylight‐Blocked Approach (SBA): An Experiment in Honghu Lake, China

AbstractWater‐leaving radiance (Lw), or remote sensing reflectance (Rrs), is a fundamental parameter of water color remote sensing. However, obtaining accurate and precise measurements of Lw is quite challenging. This study is intended to illustrate the design and implementation of a novel floating optical buoy (FOBY) to measure Lw directly in the field based on the skylight‐blocked approach (SBA). To assess the performance of FOBY, an experiment was conducted in Honghu Lake, China, a typical shallow turbid lake. FOBY‐derived Rrs can characterize the spectral features of different water types including water with kelp as substrate, relatively high chlorophyll‐a contents, and high amounts of suspended sediment (SS). FOBY‐derived Rrs is superior to that from a portable spectroradiometer (PSR 3500+, Spectral Evolution Inc.) based on the conventional above‐surface approach (ASA) in terms of data quality and stability. FOBY measurements had a quality assurance score (QAS) of 0.98 and a mean coefficient of variation (CV) of 3.6–7.0%, while the mean CV for PSR measurements is more than 2 times larger than that of FOBY in the visible domain. The measurement uncertainties may result from self‐shading, sensor tilt, and the immersed depth of the cone (IDC), which deserve further investigations. In the future, long‐term continuous floating observations of different aquatic environments can be conducted using the instrument with well‐refined data quality control.

Dynamics of phosphorus composition in suspended particulate matter from a turbid eutrophic shallow lake (Lake Chaohu, China): Implications for phosphorus cycling and management

Particulate phosphorus (P) dominates the total P (TP) content in lacustrine water columns and is a primary source of dissolved P in turbid eutrophic shallow lakes. However, the spatiotemporal variability of P compositions in suspended particulate matter (SPM) remains poorly understood. In this study, we applied chemical extraction and solution 31P nuclear magnetic resonance (31P NMR) to assess the seasonal variations of SPM P compositions from a shallow turbid lake (Lake Chaohu, China) and its main river tributaries. P fractionation analysis indicated that mobile P (the sum of labile-P, iron-bound P, and organic P) accounted for >60% of the TP in SPM and showed high spatiotemporal variability throughout the year-long field investigation. In most seasons, riverine SPM (in urban rivers or rivers with high flow) contained a higher mobile P content than that of the lake and was therefore a dominant source of lacustrine mobile particulate P. Solution 31P NMR identified five types of P compounds in SPM, with highest contributions from orthophosphate. Organic P components and concentrations showed high seasonal variability, and elevated p values occurred during the summer algal bloom. The correlation analysis between organic and inorganic P fractions inferred the possible degradation of organic P into reactive inorganic components of SPM. Consequently, biological or chemical processes would further transform the labile inorganic P into soluble reactive phosphorus, which is readily utilized by lacustrine algae. Our results suggest that the labile forms of P in SPM were highly dynamic and significantly contributed to the eutrophication of the turbid shallow lake.

Estimated light compensation depth explains growth of Stuckenia pectinata in Te Waihora

Loss of a long-term stable submerged macrophyte community reverses shallow lakes from a clear into a turbid water state. Stuckenia pectinata densely colonised the marginal area of a shallow coastal lagoon Te Waihora (Lake Ellesmere) before its removal by the 1968 “Wahine” storm. This study aims to understand the current light availability for S. pectinata growth in Te Waihora with high turbidity and water level fluctuations. In a greenhouse experiment, acclimations in S. pectinata to lower light intensities involved elongation in stems and leaves, and an increase in photosynthetic efficiency per unit dry weight for both leaves and stems. However, these acclimations did not reduce the daily compensation irradiance (under which daily net photosynthesis equals zero) that was identified at 8.8 ± 0.9 μmol photons m−2 s-1. Subsequently, we estimated light compensation depth (LCD), based on the derived daily compensation irradiance, incident irradiance at the water surface, and light attenuation coefficients for the lake. In areas shallower than LCD, there is no light limitation for the growth of S. pectinata. The LCD ranged from 0.23 to 0.54 m and well explained the growth range of S. pectinata in Te Waihora during the 2016–2017 ecological survey. The estimated LCD also suggests low turbidity levels in early spring are critical for the growth of S. pectinata with the current water level fluctuation regimes. LCD is a useful parameter for understanding the growth of submerged macrophytes in shallow turbid lakes from the perspective of light availability.

Benthic hotspots in the pelagic zone: Light and phosphate availability alter aggregates of microalgae and suspended particles in a shallow turbid lake

AbstractLimnetic aggregates from a turbid delta lake with low dissolved nutrient availability were studied in relation to light and dissolved nutrient availability. Quick light‐attenuation restricts the euphotic zone to the top surface layer of the water column, whereas mineralization processes in the sediment specifically provide dissolved nutrients near the lakebed. This suggests neither the pelagic nor the benthic zone provides the combination of resources required for microalgal growth. Nutrient mineralization in aggregates could bridge this apparent spatial gap in light and nutrients by providing dissolved nutrients in the euphotic zone, promoting microalgal growth. To explore this, aggregates obtained from turbid and phosphate‐limited lake Markermeer (The Netherlands) were exposed in the laboratory to phosphate‐replete and phosphate depleted conditions, at high‐light and low‐light availability. Confocal microscopy revealed that aggregates exhibited alkaline phosphatase activity and contained microalgae, other microbes, and extracellular polymeric substances. The spatial distribution of the phosphatase activity in aggregates largely matched that of chlorophyll a (Chl a)‐lacking microbes, suggesting that these microbes were responsible for the activity. Colorimetric quantification revealed that aggregates exhibited over 1.9‐fold higher phosphatase activity than surrounding water. Two‐day exposure to different light and phosphate availabilities affected aggregate composition. Phosphate depleted conditions resulted in more Chl a‐lacking microbes and more phosphatase activity than phosphate‐replete conditions. Low‐light intensity resulted in higher abundance of extracellular polymeric substances than high‐light intensity. In contrast to aggregates from deep stratified systems, Markermeer aggregates were not enriched with dissolved phosphorus. These results suggest that P‐cycling in aggregates differs between shallow turbid and deep stratified ecosystems.

Unusual behaviour of phototrophic picoplankton in turbid waters.

Autotrophic picoplankton (APP) abundance and contribution to phytoplankton biomass was studied in Hungarian shallow lakes to test the effect of inorganic turbidity determining the size distribution of the phytoplankton. The studied lakes displayed wide turbidity (TSS: 4–2250 mg l-1) and phytoplankton biomass (chlorophyll a: 1–460 μg l-1) range, as well as APP abundance (0 and 100 million cells ml-1) and contribution (0–100%) to total phytoplankton biomass. Inorganic turbidity had a significant effect on the abundance and contribution of APP, resulting in higher values compared to other freshwater lakes with the same phytoplankton biomass. Our analysis has provided empirical evidence for a switching point (50 mg l-1 inorganic turbidity), above which turbidity is the key factor causing APP predominance regardless of phytoplankton biomass in shallow turbid lakes. Our results have shown that turbid shallow lakes are unique waters, where the formerly and widely accepted model (decreasing APP contribution with increasing phytoplankton biomass) is not applicable. We hypothesize that this unusual behaviour of APP in turbid waters is a result of either diminished underwater light intensity or a reduced grazing pressure due to high inorganic turbidity.

Reconstruction of long-term changes of the underwater light field in large shallow lakes Peipsi and Võrtsjärv, North-East Europe

The main objective of our study was to reconstruct the multi-decadal changes of the underwater light field in two large, shallow and polymictic Estonian lakes Vortsjarv and Peipsi in order (i) to assess the potential role that light limitation may have had on phytoplankton growth in the past and (ii) to get an insight into the factors driving underwater light climate in shallow turbid lakes in the long term. We reconstructed the long-term variations of the diffuse attenuation coefficient of water (Kd,PAR) in the photosynthetically active region (PAR, 400-700 nm) partly on the basis of measured beam attenuation spectra and partly using regression analysis. From Kd,PAR we calculated the depth of the euphotic zone (z1%) and the mean light availability in the mixed layer (Emix). The reconstructed time series of these bio-optical parameters gave a plausible picture of the long-term development of light conditions in the two lakes studied, which was in accordance with their eutrophication history and changes in their water levels. Better light availability in both lakes generally coincided with years of a low water level, and the coincidence was more distinct in the shallower Vortsjarv. Values of Emix revealed a probable light limitation in Peipsi in autumn and in Vortsjarv throughout the year.

Relationship between horizontal hydroacoustic stock estimates and gillnet catches of surface-oriented fish in shallow Lake Balaton (Hungary)

We examined whether gillnetting and hydroacoustics provide comparable relative fish density and fish size distribution estimates in the uppermost water layer of a shallow turbid lake and whether the inclusion of environmental and stock parameters could improve comparability of data between different gears. According to gillnetting, most fish shorter than 14 cm in total length were Alburnus alburnus, and most fish longer than 14 cm were Pelecus cultratus. Size distributions and median sizes obtained from gillnetting and acoustics differed. Pure acoustics-derived density estimates accounted for only <8.8% of the variation in the gillnet catch by number and no correlation was found in biomass indices. Most variances observed in the gillnet catch-per-unit-effort data were associated with water transparency, none of the other investigated variables had significant explanatory power. We conclude that the feasibility of establishing a powerful model describing the relationship between fish density estimates of gillnetting and acoustics is low in shallow and turbid habitats, and it might be successful only if the crucial sampling and environmental parameters affecting catch efficiency of gillnets and post-processing of acoustic data are considered. This study cautions again that gillnetting should be used carefully to analyse trends of fish abundance.

Periodic picophytoplankton predominance in a large, shallow alkaline lake (Lake Fertő, Neusiedlersee)

The biomass and composition of the phytoplankton was studied at seven sampling stations located at different water bodies (open water, inner pond and canal) of a large, shallow turbid lake (Lake Fertő, Neusiedlersee). The open water was characterized by picocyanobacteria and meroplanktonic diatoms, the artificial canal by epiphytic diatoms, cryptophytes and chlorophytes. The inner ponds, based on the phytoplankton composition, were positioned between these water bodies. High picoplankton abundance (>10 6 cells.mL −1 ) and predominance (up to 80% contribution to the total phytoplankton biomass) were detected in the open water and the inner ponds, which was hypothesized to be the result of the turbid environment by the suppression of the top down control and by light-limitation. Information on the diversity of the picoplankton in the open water of the lake has been presented first time in this study. Based on molecular analysis (16S rRNA gene and cpcBA -IGS region) the dominant group of picocyanobacteria belonged to the Cyanobium gracile cluster (group A) of the picophytoplankton clade in April. Members of two other picocyanobacterial groups (group B and C) were also detected.

Restoration options for potential persistence of submersed aquatic vegetation: combining ecological, hydrodynamic and sediment transport modelling

Summary1. Restoration of shallow turbid lakes to promote growth of submersed aquatic vegetation (SAV) requires knowledge of the environmental factors affecting SAV growth and persistence, and a means to predict the success of SAV reestablishment under different management scenarios to improve these environmental conditions. We used a dynamic ecological modelling approach relating SAV responses to changes in physical and chemical conditions, with information on water level, flow and transparency being provided by hydrodynamic and sediment transport models.2. The potential persistence of Vallisneria americana was similar under simulated environmental conditions in 1946 and in 1954, as was the potential persistence of Potamogeton pectinatus, indicating that the disappearance of V. americana from Peoria Lake (U.S.A.) previously attributed to an extended spring flood in 1954, may have been related to the combined effects of changes in water level, flow and water transparency as well as possibly other factors.3. Recent environmental conditions (for 2000) proved not to be conducive for the colonization and persistence potential of V. americana, but would allow colonization by P. pectinatus. The construction of a hypothetical levee along the eastern descending line of the navigation channel in Upper Peoria Lake, which was expected to reduce fetch‐ and navigation‐related turbidity, did not improve the situation for V. americana and overall deteriorated the situation for P. pectinatus. Thus, such a hydraulic alteration, generally considered as beneficial for SAV restoration, may not always be successful.4. The results of the simulations indicated that the environmental conditions for potential persistence in Peoria Lake were generally less favourable for V. americana than for P. pectinatus. Measures suggested to restore SAV communities in such a lake should aim at reducing concentrations of total suspended solids at the point of inflow by a factor of three to four and limiting fetch‐ and navigation‐related resuspension.

Phytoplankton seasonality of a shallow turbid lake

This work analyses the seasonality of phytoplankton (species richness, biovolume, diversity, abundance and dominance) associated with some physical, chemical and climatic variables of shallow turbid lake (Tatlι Lake, Turkey) between February 2000 and April 2001. Samples were collected monthly from the two stations from the surface (0–20 cm). Species richness and diversity (Shannon-Weaver, H’) index were calculated. Seasonal changes in phytoplankton community structure (i. e., the species present and their relative abundances) were evaluated with Nonmetric Multidimensional Scaling (NMDS) ordinations. Canonical Correspondence Analysis (CCA) was used to investigate the relationship between phytoplankton and physico-chemical parameters. A total of 144 species most of which belonged to the Bacillariophyta and Chlorophyta could be identified. Other taxonomic groups were Cyanoprokaryota, Euglenophyta, Pyrrophyta, Cryptophyta and Xanthophyta. The diatoms Cyclotella ocellata PANTOCSEK, Nitzschia palea (KUTZING) W. SMITH, Fragilaria ulna LANGE-BERTALOT and the green algae Ankistrodesmus falcatus (CORDA) RALFS show continuously high portions in the phytoplankton assemblage. High salinity and turbidity of the lake restricted the species number.

Reconstruction of the Time Series of the Underwater Light Climate in a Shallow Turbid Lake

Lake Ulemiste is a shallow, eutrophic lake which has served the city of Tallinn as a water reservoir for many centuries. Its light climate was studied by combining a routinely measured data set with a modelling approach. For 26 years (1978–2004), data was collected on such optically active substances (OAS) and water parameters as water colour, turbidity and phytoplankton biomass. Simple modelling enabled the quantification of long-term time-series data and the subsequent calculation of the diffuse attenuation coefficient, euphotic depth and average light of the mixed layer. Several changes in the hydrological cycle have taken place during the period under study, among which are an increase in the water level of about 0.5 m and a decrease in the external water load from 108 million m3 year−1 to about 25 million m3 year−1. At the same time euphotic depth has shown a distinct trend towards increasing since the early 1990s. The euphotic depth also showed an increase (from 1.1 to 1.4 m) due to an improvement in underwater light conditions – mainly in the spring (April and May) and autumn (October and November) because of the lower amount of dissolved organic matter in the lake. The average light availability in the mixed layer has increased, but this has not affected the phytoplankton biomass as the latter is not light-limited during the summer period.

An empirical model describing the seasonal dynamics of phosphorus in 16 shallow eutrophic lakes after external loading reduction

Based on monthly mass balances on 7–8 yr of data from 16 shallow (mean depth: 1‐10 m), eutrophic, unstratified, or only temporarily stratified Danish lakes, we developed a simple empirical model relating the seasonal variation in lake total phosphorus (TP) concentrations to external loading, accumulated phosphorus in the sediment, hydraulic retention time, and water temperature. The aim was to describe the early recovery phase following an external loading reduction, i.e., when internal phosphorus loading is high, and to include seasonal dynamics. We calibrated a common set of model parameters for all 16 lakes and lake‐specific estimates of the exchangeable phosphorus pool in the sediment (Ps). Estimated annual mean TP deviated on average 12% from observed values in the 16 lakes. Moreover, the estimated seasonal dynamics and trend following the external loading reduction closely mimicked the observed pattern. The model was successfully tested on nine of the lakes for which data were available for an additional 7‐yr period. The results suggest that TP in the sediment does not provide an adequate description of the exchangeable P pool. In Lake Arreskov, which has shifted from a turbid to a clear‐water state following fish kill and biomanipulation, the model significantly overestimated TP, indicating that the model is inadequate for describing seasonal dynamics during the shift from a turbid to a clear‐water state. Although simple, the empirical model predicts reasonably well the seasonal dynamics of TP following a P‐loading reduction in a variety of shallow turbid lakes.

Diel Variations in the Vertical Distribution of Crustacean Zooplankton and Food Selection by Planktivorous Fish in a Shallow Turbid Lake

AbstractThe variations in the vertical migrations by zooplankton and food composition of fish in the shallow, clay‐turbid Mustionselkä basin of Lake Hiidenvesi were studied (water depth 3 m). Daphnids showed signs of reverse migration, their density in the surface layer being highest during the day. The reverse migration was probably due to predation threat by the predatory cladoceran Leptodora kindtii. Chydorus sphaericus, which was consumed especially by the day active bleak (Alburnus alburnus), showed normal vertical migration. Copepods showed no clear vertical movements. Leptodora kindtii, as well as the large herbivore Limnosida frontosa, showed no vertical migrations, but their overall abundance increased considerably during the night, indicating horizontal movement towards the open water at night. Due to the shallowness of the water, vertical migrations may not be a good predator‐avoidance strategy for the largest cladocerans, which may be able to perform horizontal migrations. (© 2004 WILEY‐VCH Verlag GmbH &amp; Co. KGaA, Weinheim)

Macrophyte-Dominated and Turbid States of Shallow Lakes: Evidence from Alberta Lakes

Ecosystems may exist in more than one state. This provocative ecological theory was initially developed and addressed largely through modeling studies, but over the last 2 decades a number of diverse ecosystems have been shown to display alternate states. Here I present data from 30 lakes located in a relatively limited geographic region (Alberta, Canada) to seek evidence for alternate states in shallow prairie lakes. The lakes that I surveyed fell into the following three clusters based on their turbidity and maximum depth: (a) deep, relatively clear dimictic lakes, (b) shallow clear polymictic lakes, and (c) shallow turbid polymictic lakes. The shallow lakes had similar proportions of lake bottom supporting the growth of rooted submerged macrophytes, yet the macrophyte biomass was approximately five times higher in shallow clear lakes than in shallow turbid lakes. An analysis of covariance (ANCOVA) revealed that there was a significantly higher concentration of chlorophyll per unit of dissolved phosphorus in shallow lakes classified as turbid compared to those classified as clear. A separate ANCOVA also showed that the higher turbidity in the turbid lakes was not due simply to higher chlorophyllaa concentrations; rather, it appears that increased sediment resuspension is the source of the higher turbidity seen in these lakes. Food web effects appear to be small. Although these shallow Alberta lakes contain no benthic fishes, as do many European lakes that have been observed over time, the general patterns are consistent with the theory that alternate states can exist in shallow lakes.

Cyanobacterial toxins in Lake Baringo, Kenya

This paper presents data on the first identification, characterization and quantification of hepatotoxic microcystins and neurotoxic anatoxin-a in water samples of Lake Baringo, Kenya. The shallow turbid Lake Baringo was investigated five times between June 2001 and May 2002. The phytoplankton community was mainly dominated by the cyanobacterium Microcystis aeruginosa. Due to the high turbidity the phytoplankton biomass was low, ranging between 1.5 and 8.2 mg L −1. High mean total phosphorus concentration (1.0 mg L −1) and mean total nitrogen concentration (2.8 mg L −1) typical for hypertrophic lakes were found. Using HPLC technique the hepatotoxins microcystin-LR, -RR and -YR and the neurotoxin anatoxin-a were detected in the water samples. The microcystin concentrations varied from 310 to 19800 μg microcystin-LR equivalents g −1 DW and the anatoxin-a concentration ranged from 270 to 1260 μg g −1 DW. To our knowledge this is the first evidence of cyanobacterial toxins in Lake Baringo.

Eutrophication and restoration of shallow lakes – the concept of stable equilibria revisited

Shallow polymictic lakes are very abundant in many regions of the world, they are more numerous than deep lakes and are of great importance especially in densely populated areas even when small. Their ecology differs from stratified lakes in many ways. During the eutrophication process, lakes may change from a clear water, macrophyte dominated state to an algal dominated state, a process known as the concept of ‘alternative stable equilibria’. The usefulness of this concept as a descriptor for the eutrophication process and as the basis for rehabilitation of lakes is tested on long-term data from two contrasting case study sites using a novel multivariate bubble-plot technique. In one case the concept proved to be useful and successful while it could not be applied to a large shallow turbid lake. The equilibrium concept is then generalised using further examples. Shallow lakes which are either macrophyte dominated or light limited because of high inorganic background turbidity have ratios of total phosphorus (TP) to algal Chlorophyll-a at or below 3:1. Deep oligotrophic or algal dominated lakes in contrast exhibit ratios between 3:1 and 1:1. Alternative stable equilibria of macrophyte or algal domination can occur within the same water-body at various locations, at different times of the year or during trophic development.