Potential and Constraints of Macrophyte Manipulation for Shallow Lake Management

Abstract

Palic and Ludas lakes are shallow Pannonian lakes, which have undergone rapid eutrophication. High concentrations of nutrients, along with significantly high values of fecal indicators in water samples, indicate that the Palic-Ludas canal, which connects them, contributes to the pollution of the recipient Lake Ludas, a central part of a special nature reserve. In order to improve water quality in the canal and decrease nutrient load of Lake Ludas, it is suggested to use environmentally friendly solutions, so-called bio-barriers (bio-bridges and biobanks), which will contribute to self-purification efficiency. The given model assumes 10 zones with bio-bridges and 0.4 ha covered by biobanks, using plants common in the area, e.g. Typha spp., Phragmites spp., Juncus spp., Scirpus spp. and Carex spp. The main disadvantage of this technology is occupation of large area; thus, the solution seems to be undersized. It removes 4% TN/year and 8% TP/year of the total amount necessary to achieve good ecological status. Nevertheless, the role of bio-bridges in permanent nutrient removal, through preventing the deposition of organic matter at the bottom sediment and later return of nutrients in water, together with indirect influence through enhancement of biodiversity should not be underestimated.

Past studies and potential measures for rehabilitation of the shallow lake (Lake Ludas)

“…Processed water was fed into Lake Palić. At that time Lake Palić was split into four sectors in order to extend retention time (Rudic et al, 2018). The problem is that the nominal volume of Lake Palić is around 10 million m discharged from WWTP is 13 million m 3 per year.…”

“…For instance, Tokodi et al (2018) carried out in vitro assessment of a chemical method based on hydrogen peroxide treatment, but they concluded that the application of a dose required for successful cyanobacterial control would also be harmful to other aquatic organisms. On the other hand, Rudic et al (2018) suggested the construction of wetlands, bio-bridges and biobanks, which can improve self-purification process. This method of so-called bio-barriers would be based on autochthonous plants, for example Typha spp, Phragmites spp., Carex spp., etc.…”

“…Two aeolian lakes in northern Serbia, Lake Palić and Lake Ludaš, are probably the most investigated shallow water bodies in the country. Studies dealing with Lake Ludaš include various topics: water and sediment quality, changes and modeling of its hydrological regime, microbiological community and phytoplankton dynamics, cyanobacterial bloom and their toxic effect on other aquatic organisms (Ćirić et al, 2019;Gavrilović et al, 2020;Grabić, Đurić, Ćirić, & Benka, 2018;Grba et al, 2017;Pamer et al, 2011;Raicevic et al, 2013;Rudic et al, 2018;Rudić, Vujović, Božić, Arizanović, & Raičević, 2018;Rudić, Vujović, Božić, & Raičević, 2015;Seleši, 1981Seleši, , 2006Svirčev et al, 2013;Tokodi, 2016;Tokodi et al, 2018;Tokodi et al, 2020).…”