Abstract
This study reports the spatial distributions of diatom assemblages and potential relationships between diatom diversity and environmental variables (C/N ratio, CaCO3%, clay mineralogy) using multivariate analyses in surface sediments of the Akkulam-Veli Lake. Surface sediment samples were collected at 19 sites throughout the lake to analyse diatom distribution, TOC, N, CaCO3%, clay mineralogy and sediment texture. The results suggest that the clay fraction is predominant in the eastern flank, whereas sand fraction is more in the western flank. TOC% and CaCO3% in the lake floor sediments are attributed to high organic activity within the lake and contributions from the vegetation around the lake margins. The results suggest that N is being added to the lake from secondary sources from catchment area leading to eutrophication of the lake. Further, clay mineralogy of the sediment samples reveals that kaolinite mineralogy dominates in clay fractions. Diatom studies show rich diversity of freshwater, marine and brackish diatoms and abundance of pollution-reflecting species such as Cyclotella sp. and Navicula sp.
Highlights
Fluvial transport of sediments incorporates both internal and external materials into lake basins, and such transported material could preserve important environmental information about lakes and their catchments (Liu et al 2017; Meyers 2003)
The grain size spatial distribution maps (Fig. 3a–c) in the Akkulam-Veli Lake display prominent zones of the different sediment fractions formed by the differential water energy
This study on the Akkulam-Veli lake floor sediments reveals that the lake is dominated by sand towards the Veli part and clay and silt towards the Akkulam part
Summary
Fluvial transport of sediments incorporates both internal and external materials into lake basins, and such transported material could preserve important environmental information about lakes and their catchments (Liu et al 2017; Meyers 2003). Applied Water Science (2019) 9:188 and as a natural regulator of the processes that occur in the lake floor (Jorgensen 1996). Morphological parameters, such as bathymetry, volume, land-use and land-cover pattern around the lake catchment, significantly influence nutrient concentrations or eutrophication status of a lake basins (Silvino and Barbosa 2015). Nutrient concentration (mainly N, P and TOC) derived from either terrestrial source or autochthonous source is the major factor resulting in widespread degradation of ecological structure and function of lake ecosystems (Saluja and Garg 2017). Lake ecosystems are strongly influenced by dissolved organic matter, autochthonous flora and fauna and terrestrial vegetation and pollutant inputs derived from the catchment areas (Solomon et al 2015). Terrestrial inputs into the lake basins have accelerated substantially in recent decades as a result of increasing anthropogenic influences
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