Microcystin concentration in fishpond waters

Cyanobacterial blooming is a worldwide problem which sometimes results in cyanotoxin production. Most commonly produced cyanotoxins are microcystins (MCs), potent inhibitors of protein phosphatases. Protein phosphatase 1 (PP1) is known to be involved in the regulation of a variety of cellular processes. In this study, MC concentration was assessed via inhibition of protein phosphatase 1 (PP1 assay) in water samples taken from 14 lakes of Mužlja fishpond, Vojvodina, Serbia. During the summer of 2011, cyanobacterial growth occured in the fishpond lakes and small, planktonic crustacean Daphnia sp. was used to control or/and prevent further development of cyanobacteria. Different MC concentrations (calculated as microcystin-LR equivalents) were detected, mostly depending on the occurrence and grazing of Daphnia sp. More thorough monitoring of fishponds should be conducted, both in Serbia and around the world, in order to gain more precise estimation of cyanotoxin concentrations and their accumulation in organisms used for human consumption and thus prevent possible negative health effects. [Projekat Ministarstva nauke Republike Srbije, br.176020

Protected freshwater ecosystem with incessant cyanobacterial blooming awaiting a resolution

© 2019 by the authors. For 50 years persistent cyanobacterial blooms have been observed in Lake Ludos (Serbia), a wetland area of international significance listed as a Ramsar site. Cyanobacteria and cyanotoxins can affect many organisms, including valuable flora and fauna, such as rare and endangered bird species living or visiting the lake. The aim was to carry out monitoring, estimate the current status of the lake, and discuss potential resolutions. Results obtained showed: (a) the poor chemical state of the lake; (b) the presence of potentially toxic (genera Dolichospermum, Microcystis, Planktothrix, Chroococcus, Oscillatoria, Woronichinia and dominant species Limnothrix redekei and Pseudanabaena limnetica) and invasive cyanobacterial species Raphidiopsis raciborskii; (c) the detection of microcystin (MC) and saxitoxin (STX) coding genes in biomass samples; (d) the detection of several microcystin variants (MC-LR, MC-dmLR, MC-RR, MC-dmRR, MC-LF) in water samples; (e) histopathological alterations in fish liver, kidney and gills. The potential health risk to all organisms in the ecosystem and the ecosystem itself is thus still real and present. Although there is still no resolution in sight, urgent remediation measures are needed to alleviate the incessant cyanobacterial problem in Lake Ludos to break this ecosystem out of the perpetual state of limbo in which it has been trapped for quite some time

Cyanobacteria, cyanotoxins, and their histopathological effects on fish tissues in Fehérvárcsurgó reservoir, Hungary

Cyanobacteria are important members of lake plankton, but they have the ability to form blooms and produce cyanotoxins and thus cause a number of adverse effects. Freshwater ecosystems around the world have been investigated for the distribution of cyanobacteria and their toxins and the effects they have on the ecosystems. Similar research was performed on the Fehérvárcsurgó reservoir in Hungary during 2018. Cyanobacteria were present and blooming, and the highest abundance was recorded in July (2,822,000 cells/mL). The species present were Aphanizomenon flos-aquae, Microcystis flos-aquae, Microcystis wesenbergii, Cuspidothrix issatschenkoi, Dolichospermum flos-aquae, and Snowella litoralis. In July and September, the microcystin encoding gene mcyE and the saxitoxin encoding gene sxtG were amplified in the biomass samples. While a low concentration of microcystin-RR was found in one water sample from July, analyses of Abramis brama and Carassius gibelio caught from the reservoir did not show the presence of the investigated microcystins in the fish tissue. However, several histopathological changes, predominantly in gills and kidneys, were observed in the fish, and the damage was more severe during May and especially July, which coincides with the increase in cyanobacterial biomass during the summer months. Cyanobacteria may thus have adverse effects in this ecosystem