scholarly journals Effect of under-ice light intensity and convective mixing on chlorophyll a distribution in a small mesotrophic lake

2019 ◽  
Vol 46 (3) ◽  
pp. 259-269
Author(s):  
N. I. Palshin ◽  
G. E. Zdorovennova ◽  
R. E. Zdorovennov ◽  
T. V. Efremova ◽  
G. G. Gavrilenko ◽  
...  
Keyword(s):  
Solar Radiation ◽  
Water Temperature ◽  
Chlorophyll A ◽  
Chlorophyll Concentration ◽  
Bottom Surface ◽  
Lake Surface ◽  
Convective Mixing ◽  
Radiation Fluxes ◽  
Coefficients Of Variation

Data of long-term measurements of under-ice solar radiation, water temperature, and chlorophyll a are analyzed in four phytoplankton groups (green, diatoms, blue-green, and cryptophyte algae) in a small mesotrophic Vendyurskoe Lake (Karelia) in the period of spring under-ice convection. It is shown that, after thawing away of snow cover from lake surface, under-ice illumination increases, water temperature rises, the depth of convectively mixed layer (CML) increases, and microalga photosynthesis intensifies. In the daytime, chlorophyll a extremums appear in the CML, and, unlike the homogeneous characteristics (water electric conductivity, mineralization, etc.), the cells of different phytoplankton species can be used as tracers in studying convective mixing. A prognostic equation is obtained, reflecting an inverse dependence of the coefficients of variation of chlorophyll a concentration in CML on solar radiation fluxes, penetrating under ice bottom surface. A direct relationship was shown to exist between the increase in chlorophyll concentration in CML and its thickness.

scholarly journals Effects of Long-Term Increases in Water Temperature and Stratification on Large Artificial Water-Source Lakes in South Korea

Water ◽  
2021 ◽  
Vol 13 (17) ◽  
pp. 2341
Author(s):  
Soon-Ju Yu ◽  
Ju-Yeon Son ◽  
Ho-Yeong Kang ◽  
Yong-Chul Cho ◽  
Jong-Kwon Im
Keyword(s):  
South Korea ◽  
Water Temperature ◽  
Aquatic Ecosystems ◽  
Water Source ◽  
Lake Surface ◽  
Lake Water Quality ◽  
Slope Estimator ◽  
Artificial Water ◽  
Lake Stratification

Long-term changes in air and water temperatures and the resulted stratification phenomena were observed for Soyang Lake (SY), Paldang Lake (PD), Chungju Lake (CJ), and Daecheong Lake (DC) in South Korea. Non-parametric seasonal Kendall and Mann-Kendall tests, Sen slope estimator, and potential energy anomaly (PEA) were applied. The lake surface water temperatures (LSWTs) of SY and DC increased at the same rate (0.125 °C/y), followed by those of CJ (0.071 °C/y) and PD (0.06 °C/y). Seasonally, the LSWT increase rates for all lakes, except PD, were 2–3 times higher than the air temperature increase rates. The lake stratification intensity order was similar to those of the LSWT increases and correlations. SY and DC displayed significant correlations between LSWT (0.99) and PEA (0.91). Thus, the LSWT significantly affected stratification when the water temperature increased. PD demonstrated the lowest correlation between LSWT and PEA. Inflow, outflow, rainfall, wind speed, and retention time were significantly correlated, which varied within and between lakes depending on lake topographical, hydraulic, and hydrological factors. Thus, hydraulic problems and nutrients should be managed to minimize their effects on lake water quality and aquatic ecosystems because lake cyanobacteria can increase as localized water temperatures increase.

Long-term effects of hydrometeorological and water quality conditions on algal dynamics in the Paldang dam watershed, Korea

2014 ◽  
Vol 14 (4) ◽  
pp. 601-608
Author(s):  
D.-W. Kim ◽  
J.-H. Min ◽  
M. Yoo ◽  
M. Kang ◽  
K. Kim
Keyword(s):  
Water Quality ◽  
Water Temperature ◽  
Chlorophyll A ◽  
Algal Bloom ◽  
Temporal Variations ◽  
Regulated River ◽  
Han River ◽  
Nutrient Levels ◽  
Short Period

The primary goal of this study is to shed light on some important factors that control algal bloom in a large-scale regulated river system. Long-term impacts of environmental conditions on algal dynamics were investigated in the Paldang dam watershed, Korea. Dam inflow, water temperature, chlorophyll-a, TN, PO4-P and TP data collected at five major dams located on the North Han River (NHR) and at four water quality monitoring sites on the South Han River were analyzed for 21 years (1992 to 2012) to examine spatio-temporal variations in each. A pattern of slightly increasing chlorophyll-a and nutrient levels in the NHR since 2001 indicates that algal dynamics were affected by the increased nutrient levels as well as the reduced flow conditions (−10% to −37%). The temporal variations in monthly averaged data collected during summer monsoon seasons (mainly July) over the two decades show that high chlorophyll-a levels observed in both rivers corresponded to the relatively lower flow condition, which means a reduced amount of dam water release due to low or no rainfall over a short period of time, and abnormally high water temperature. This study shows that flow control is most critical for effectively managing algal level in the rivers in the short term, and nutrient management in the watershed is the key to reducing the potential for algal bloom in the long term.

scholarly journals Relative impacts of increases of solar radiation and air temperature on the temperature of surface water in a shallow, eutrophic lake

2021 ◽  
Author(s):  
Ryuichiro Shinohara ◽  
Yoji Tanaka ◽  
Ariyo Kanno ◽  
Kazuo Matsushige
Keyword(s):  
Heat Flux ◽  
Surface Water ◽  
Solar Radiation ◽  
Water Temperature ◽  
Air Temperature ◽  
Heat Fluxes ◽  
Shortwave Radiation ◽  
Surface Water Temperature ◽  
Lake Kasumigaura ◽  
Lake Surface

Abstract We monitored lake surface water temperatures from 1992 to 2019 in Lake Kasumigaura, a shallow lake in Japan. We hypothesized that increases of shortwave radiation had increased surface water temperatures and heat fluxes more than had the increases of air temperature. We used the heat flux analyses and the sensitivity analyses to test the hypothesis. The fluxes of solar radiation gradually increased during the study period in a manner consistent with the phenomenon of global brightening. The increase was especially apparent in the spring. The rate of increase of surface water temperature was especially significant in May. Air temperature did not significantly increase in May, but it increased significantly in June (0.40 °C decade−1). A sensitivity analysis of the heat fluxes at the lake surface (shortwave radiation, longwave radiation, latent heat flux, and sensible heat flux) revealed that surface water temperature was more sensitive to changes of shortwave radiation than to air temperature during the spring. Although other factors such as inflows of groundwater and river water may also have impacted surface water temperatures, the increase of solar radiation appeared to be the major factor responsible for the increase of surface water temperature during the spring in Lake Kasumigaura.

scholarly journals Dynamics of chlorophyll a concentration in the Black Sea on satellite data

2019 ◽  
Vol 4 (2) ◽  
pp. 87-95 ◽  
Author(s):  
Z. Z. Finenko ◽  
I. M. Mansurova ◽  
V. V. Suslin
Keyword(s):  
Chlorophyll A ◽  
Black Sea ◽  
Satellite Data ◽  
Large Scale ◽  
Mixed Layer Depth ◽  
Chlorophyll Concentration ◽  
Shelf Zone ◽  
The Black Sea ◽  
Convective Mixing ◽  
Stability Of Water

The use of satellite data to study the chlorophyll a dynamics, in contrast to contact methods, allows carrying out large scale research with high frequency of measurements. Such observations were carried out in the Black Sea offshore and inshore areas from 1998 to 2015. They made it possible to estimate the annual and interannual chlorophyll a dynamics in the surface layer and to reveal the periodicity, intensity, and duration of mass development of algae. In the western and eastern cyclonic gyres as well as in the shelf zone off the Crimean and Caucasus coasts, annual chlorophyll dynamics had the same pattern as that repeating year after year. From August-September to April-May of the next year the variation of chlorophyll in most cases corresponded to normal distribution and had a form of a bell-shaped curve with maximum observed in December-January. During autumn period, the chlorophyll concentration gradually increased with water cooling and seasonal pycnoclyne weakening. In winter the chlorophyll concentration decreased due to increase of mixed layer depth. Spring phytoplankton intensive development was observed every year when convective mixing weakened and stability of water column increased.

scholarly journals Detection range and efficiency of acoustic telemetry receivers in a connected wetland system

Hydrobiologia ◽  
2021 ◽  
Vol 848 (8) ◽  
pp. 1825-1836
Author(s):  
Emily R. Winter ◽  
Andrew M. Hindes ◽  
Steve Lane ◽  
J. Robert Britton
Keyword(s):  
Water Temperature ◽  
Acoustic Telemetry ◽  
Detection Efficiency ◽  
Acoustic Noise ◽  
Chlorophyll Concentration ◽  
Temperature Conductivity ◽  
Detection Range ◽  
Receiver Performance ◽  
Range Testing

AbstractAcoustic telemetry is an important tool for assessing the behavioural ecology of aquatic animals, but the performance of receivers can vary spatially and temporally according to changes in environmental gradients. Studies testing detection efficiency and/ or detection range are, therefore, important for data interpretation, although the most thorough range-testing approaches are often costly or impractical, such as the use of fixed sentinel tags. Here, stationary tag data (from study animals that had either died or expelled their tags) provided a substitute for the long-term monitoring of receiver performance in a wetland environment and was complemented by periodic boat-based range testing, with testing of the effects of environmental variables (water temperature, conductivity, transparency, precipitation, wind speed, acoustic noise) on detection efficiency (DE) and detection range (DR). Stationary tag DE was highly variable temporally, the most influential factors being water temperature and precipitation. Transparency was a strong predictor of DR and was dependent on chlorophyll concentration (a surrogate measure of algal density). These results highlight the value of stationary tag data in assessments of acoustic receiver performance. The high seasonal variability in DE and DR emphasises the need for long-term receiver monitoring to enable robust conclusions to be drawn from telemetry data.

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