Cyanophytes and chlorophytes versus raphidophytes in humic lakes with different catchment basins

Abstract

The aim of the study was to evaluate the effects of coniferous forest cover in the catchment basin and relative catchment area (catchment area to lake volume ratio) on phytoplankton composition in humic lakes. The study was carried out in 11 small and shallow lakes situated in the West Polesie region (Eastern Poland). The lakes were divided with respect to forest cover in their catchment basins into two groups: high forest cover -HFC (more than 60%) and low forest cover -LFC (less than 60%). The study showed that both, land use in the catchments (proportion of forests) and the relative catchment area determined physicochemical and biological parameters in the lakes. The high relative catchment area affects their high productivity expressed by high chlorophyll a concentration and low water visibility. The lakes of the LFC group had low water colour as well as high concentration of total phosphorus (Ptot), reaction (pH), and conductivity of water and a large number of cyanophytes and chlorophytes. The dominant species, e.g., Planktolyngbya limnetica, Limnothrix planctonica, Planktothrix agardhii, Coenococcus planctonicus, were characteristic of high trophic status. In the lakes of the HFC group, Ptot, pH, conductivity of water and the contribution of cyanophytes and chlorophytes was considerably lower, whereas the water colour and the number of raphidophytes represented by Gonyostomum semen was high. The large number of raphidophytes and the small amount of chlorophytes and cyanophytes in the lakes of the HFC group indicated the lake naturalness.

Harmful Algal Blooms

“…Spring recruitment of cysts from sediments back into the water column may contribute to bloom dynamics the following year. In comparison, lakes with reduced forest cover were dominated by chlorophytes and cyanobacteria (Lenard et al, 2014). However, the factors affecting this species' successful invasion are not fully resolved, although it is most commonly found in waters with high color and humic levels, moderate-high nutrients, and lower conductivity and pH, which in turn are strongly related to catchment characteristics (Lenard et al, 2014;Pęczuła et al, 2015).…”

Chlorophytes response to habitat complexity and human disturbance in the catchment of small and shallow aquatic systems

“…Only random and detached information is available on the impact of land use in the catchments e.g. 7 or the effect of various aquatic vegetation types on the occurrence of green algae e.g. 8 , 9 .…”