Variability of bio-optical parameters in two North-European large lakes

Abstract

The bio-optical properties of some NorthEuropean large lakes were examined during 1995-2005 using field data and laboratory measurements. The key variables were optically active substances (OAS: chlorophyll, total suspended matter and dissolved organic matter), Secchi depth, and the ''spectrometric'' and diffuse light attenuation coefficients. Our main study sites were Lake Peipsi and Lake Võrtsjärv in Estonia, both eutrophic with mean Secchi depth below 3 m. The measured water parameters were compared with those obtained from two clear-water Swedish lakes, Lake Vänern and Lake Vättern. This comparison describes the biooptical differences of the water in eutrophic and oligotrophic lakes. The variability of water parameters in the turbid Estonian lakes was rather high, e.g. the chlorophyll content varied from 1.8 to 102 mg m -3 and the diffuse light attenuation coefficient from 0.92 to 6.5 m -1 . The change in water properties depends on the season and the biological activity of phytoplankton. We found no apparent long-time trend in water properties. Regression analysis showed that in the turbid Estonian lakes the optical properties were well correlated with chlorophyll and suspended matter, but not with dissolved organic matter. The highest determination coefficients (between 0.73 and 0.89) were obtained when the optical parameters were correlated with all three OAS together (multiple regressions). Our results concerning the variability and interconnections among bio-optical parameters in two Estonian large lakes illustrate the effect of OAS and light field on the ecological conditions of lakes in general.

Using Optical Water Types to Monitor Changes in Optically Complex Inland and Coastal Waters

“…Using the OWT classification performed in this study, it is possible to follow the movements of river water masses. Additionally, the OWT classification for larger lakes showed a reasonable correspondence with the results of previous studies [42][43][44][45]. Some small lakes and pixels affected by the adjacency effect were often classified as Clear.…”

Wind and submerged aquatic vegetation influence bio‐optical properties in large shallow Lake Taihu, China

“…Our Lake Taihu short‐time series analyses of wind speed, TSM concentration, and bio‐optical properties revealed that wind‐driven sediment resuspension was indeed the primary force controlling the short‐term variability in the underwater light attenuation. This is in agreement with other studies in shallow lakes and bays, using short‐term, high‐frequency observations, long‐term monitoring, remote sensing, and numerical simulations, which show that wind‐driven sediment resuspension can significantly change the concentrations of OASs and water bio‐optical properties [ Paavel et al ., ; Chen et al ., ].…”

“…The driving factors in large, shallow lakes, particularly the wind‐driven sediment resuspension, rivers input, and ship waves disturbance, lead to a wide range of temporal and spatial scales of suspended matter, phytoplankton, and SAV [ Qin et al ., , ; Istvánovics et al ., ]. Of all the dynamic disturbance effects, wind‐induced sediment resuspension is the one that most directly reduces water transparency and euphotic depth, thereby affecting the primary productivity in the lake, as well as the seasonal and spatial distribution of the SAV [ Schallenberg and Burns , ; Paavel et al ., ; Carr et al ., ; Verspecht and Pattiaratchi , ].…”

Comparison of Lake Optical Water Types Derived from Sentinel-2 and Sentinel-3

“…Its water is optically turbid and the underwater light climate is very strongly affected by the lake's water level and ice conditions [30]. Transparency measured with the Secchi disk is in the range of 0.3-1.6 m and chl-a varies from 20 to 102 mg m -3 [31]. Its catchment area (3100 km 2 ) makes up about 7% of Estonian territory and, thus, contributes significantly to the Estonian natural CO 2 budget.…”