Cyanobacteria blooms are common in Baltic Sea and their intensity have been increased due to anthropogenic eutrophication. In this study we investigated the cyanotoxin levels in the water samples collected from four different locations in the Baltic Sea at three different seasons including summer 2011. Protein phosphatase 2A (PP2A) inhibition assays, Enzyme-linked immunosorbent assays (ELISA) and liquid chromatography-mass spectrometry (LC-MS) were employed to detect cyanotoxin variants. Microcystin- LR equivalents (MCE) were detected in a number of the water samples collected at site A (0.4 to 0.64 mg MCE/ L) and at site B (0.24 to 0.44 mg MCE/ L). Cyanotoxin concentrations, as measured by ELISA, ranged between 0.98 -7.45 mg MCE/L in samples collected at site A and between 0.12 to 0.68 mg MCE/L, in samples collected at site B. By using LC-MS one of the molecules present in the samples from site A was determined to be nodularin (0.213 to 0.524 mg/L) whereas samples from site B did not contain this toxin nor did they contain any of the most toxic microcystin species mentioned. The data obtained show good correlation with the MC concentration changes measured in samples and these concentrations were relatively higher during warmer months. In addition we also investigated the adsorption of toxins from water into the circulation of grazing cattle and the results show no measureable liver damage resulting from cyanotoxin poisoning.

Cyanobacteria, ancient photosynthetic prokaryotes, form harmful blooms that degrade water quality and pose many risks to human health. The main objective of this study is to identify toxic cyanobacteria present in fish ponds, evaluate their effects on Zebrafish (Danio rerio) tissue, and investigate their characteristics. Samples were collected from the walls and floors of rainbow trout raceway ponds at Alborz Caspian Company, situated in Alborz province, Iran. The purpose of this collection was to isolate and examine cyanobacteria colonies. As a result of meticulous microscopic and macroscopic observations, three pure samples of Calothrix sp., Nostoc sp., and Microcystis sp. species were successfully identified. These samples were then transported to the laboratory and processed using the Z8 solid culture medium within a growth chamber. Cyanobacteria were identified based on their morphology using a light microscope and validated identification keys. The DNA extraction was performed using the cetyl-trimethyl-ammonium bromide method. Zebrafish were acclimated and fed with fish food containing lyophilized cyanobacteria for a period of 30 days. At specific intervals, fish were collected for histopathological analysis and measurement of antioxidant enzyme activity. The histopathological examination of intestinal tissue in the treatment groups exposed to lyophilized cyanobacteria revealed lesions including hyperplasia of enterocytes, reduction in their length, vacuolation of enterocytes, hyperplasia of goblet cells, and infiltration of lymphocytes. The gill samples from the treatment group exhibited severe histopathological abnormalities such as displacement of epithelial cells, fusion of lamellae, epithelial necrosis, and lymphocyte infiltration. These symptoms diminished over time. Hepatocellular lipid changes and vacuolation were observed in the treatment group's liver samples, peaking on the 30th day. The activity of superoxide dismutase (SOD) enzyme significantly increased in the exposed Zebrafish on the 30th day compared to the control group, and similar significant increases were observed on the 20th and 30th days (p<0. 05). There were no significant differences in Catalase (CAT) activity between the control and treatment groups (p>0. 05). Generally, the study identified specific histopathological abnormalities in the fish exposed to lyophilized cyanobacteria and observed changes in antioxidant enzymes activity. These findings contribute to understanding the impact of cyanobacteria on fish health status.

Cyanobacteria are bacteria found in different ecosystems, such as lakes and rocks. These bacteria, capable of photosynthesis, are important sources of oxygen. However, some cyanobacterial strains can produce toxins, which are harmful to humans and animals.Therefore, collection of epidemiological and surveillance data on cyanobacterial toxins in the environment is vital to ensure a low risk of exposure to toxins in other organisms. For presentation of accurate data on environmental cyanobacterial toxins, it is essential to understand their characteristics, including taxonomy, toxin proteins, and genomic structures, and determine their environmental effects on bacterial populations and toxin production. Taxonomy, which is the scientific classification of organisms, is important in identifying species producing toxins. The structure of toxin proteins and their stability in the environment allow researchers to detect toxins with analytical methods and discuss their limitations. Onthe other hand, identifying toxins via molecular typing enables researchers to investigate toxic cyanobacteria by detecting toxin-encoding genes and toxin gene expression. Meanwhile, environmental factors, such as nutrient level, light intensity, and biotic factors, allow researchers to predict the suitable time and location for accurate sampling. In this review, these cyanobacterial features, which are important for accurate detection of cyanobacterial toxins, will be discussed.