Differential Effect of Hydroxen Peroxide οn Toxic Cyanobacteria of Hypertrophic Mediterranean Waterbodies

Abstract

Cyanobacterial blooms have been known since ancient times; however, they are currently increasing globally. Human and ecological health risks posed by harmful cyanobacterial blooms have been recorded around the world. These risks are mainly associated with their ability to affect the ecosystem chain by different mechanisms like the production of cyanotoxins, especially microcystins. Their expansion and their harmful effects have led many researchers to seek techniques and strategies to control them. Among them, hydrogen peroxide could be a promising tool against cyanobacteria and cyanotoxins and it is well-established as an environmentally friendly oxidizing agent because of its rapid decomposition into oxygen and water. The aim of the present study was to evaluate the effect of hydrogen peroxide on phytoplankton from two hypertrophic waterbodies in Greece. The effect of hydrogen peroxide on concentration of microcystins found in the waterbodies was also studied. Treatment with 4 mg/L hydrogen peroxide was applied to water samples originated from the waterbodies and Cyanobacterial composition and biomass, phycocyanin, chlorophyll-a, and intra-cellular and total microcystin concentrations were studied. Cyanobacterial biomass and phycocyanin was reduced significantly after the application of 4 mg/L hydrogen peroxide in water treatment experiments while chlorophytes and extra-cellular microcystin concentrations were increased. Raphidiopsis (Cylindrospermopsis) raciborskii was the most affected cyanobacterial species after treatment of the water of the Karla Reservoir in comparison to Aphanizomenon favaloroi, Planktolyngbya limnetica, and Chroococcus sp. Furthermore, Microcystis aeruginosa was more resistant to the treatment of Pamvotis lake water in comparison with Microcystis wesenbergii and Microcystis panniformis. Our study showed that hydrogen peroxide differentially impacts the members of the phytoplankton community, affecting, thus, its overall efficacy. Different effects of hydrogen peroxide treatment were observed among cyanobacerial genera as well as among cyanobacterial species of the same genus. Different effects could be the result of the different resistance mechanisms of each genus or species to hydrogen peroxide. Hydrogen peroxide could be used as a treatment for the mitigation of cyanobacterial blooms in a waterbody; however, the biotic and abiotic characteristics of the waterbody should be considered.

Comparison of iCOR and Rayleigh atmospheric correction methods on Sentinel-3 OLCI images for a shallow eutrophic reservoir

“…However, a series of negative consequences resulting from its drainage has led to its reconstruction in 2010, in an attempt to alleviate the negative effects ( Laspidou et al, 2017 ). In its current state, the reservoir occupies a surface of 34 km 2 with a maximum water depth of 2 m ( Falaras, Koilakou & Tsoukalas, 2020 ; Papadimitriou et al, 2022 ). As a shallow reservoir, Karla appears some important environmental implications, such as eutrophication and frequent and prolonged cyanobacterial blooms that produce toxins ( Gkelis et al, 2017 ; Oikonomou et al, 2012 ; Papadimitriou et al, 2022 ).…”

“…In its current state, the reservoir occupies a surface of 34 km 2 with a maximum water depth of 2 m ( Falaras, Koilakou & Tsoukalas, 2020 ; Papadimitriou et al, 2022 ). As a shallow reservoir, Karla appears some important environmental implications, such as eutrophication and frequent and prolonged cyanobacterial blooms that produce toxins ( Gkelis et al, 2017 ; Oikonomou et al, 2012 ; Papadimitriou et al, 2022 ). Occasionally, the severity of such blooms has been associated to mass kills of fish ( Papadimitriou et al, 2013 ) and migrating birds ( Papadimitriou et al, 2018 ).…”

Recoverability of Microcystis aeruginosa and Pseudanabaena foetida Exposed to a Year-Long Dark Treatment

“…A study on M. aeruginosa revealed that light is an essential factor affecting H 2 O 2 decomposition in M. aeruginosa cells, and the difference in the promotion of catabolism in cells with and without light was evident at more than 24 h [34]. Other studies also have suggested that in vivo, H 2 O 2 has a more pronounced effect on M. aeruginosa than on other cyanobacteria or plants [35], but M. aeruginosa cells exhibit enhanced immunity under in vitro H 2 O 2 conditions [36]. Therefore, the decrease in cell growth, Chl-a, carotenoid, and other physiological indicators may result from the increased H 2 O 2 content in recovering cells, which results from changes in cell physiology during adaptation to prolonged darkness exposure.…”