Published Online: 04 Jan 2015 Page range: 329 - 336
Abstract
Abstract
Freshwater green algal biofouling of boats refers to the accrual of freshwater green algae on boats immersed in water. The current research focused on the morphological characteristics of the isolates, species ecology, and the physicochemical properties of the water at the sampling sites. Two localities, Haji Zai and Sardaryab, were sampled at the Kabul River in the district of Charsadda, Pakistan. Freshwater green algae causing biofouling were isolated from the boats. A total of three genera: Cladophora, Rhizoclonium, and Spirogyra with fifteen species belonging to the families Cladophoraceae and Zygnemataceae were observed. Statistical analysis reveals significant stimulation of green algal species in the boats’ fouled communities by increases in water temperature, conductivity, and Total Suspended Solids (TSS). The algal growth at the Haji Zai site is suppressed by TDS in autumn (Pearson −0.56) and is stimulated by water temperature in spring (Pearson 0.44). At the Sardaryab site, algae were stimulated in spring by pH of water (Pearson 0.61), and suppressed by Total Dissolved Solids (TDS) in autumn (Pearson −0.43). Statistical analysis indicates that pH, conductivity, and temperature are the main factors determining the algal biofouling in the Kabul River.
Published Online: 04 Jan 2015 Page range: 337 - 345
Abstract
Abstract
Microflora of cyanobacteria and algae of small forest dystrophic Lake Sęczek located in the Masurian Lake District, NE Poland, was investigated in 2012 and 2013. A total of 16 genera with 7 species of cyanobacteria and 56 genera with 74 species, 6 varietas and forms of algae were determined. Most of them represented commonly occurring microorganisms of slightly acidic waters, but some of them are considered rare, i.e. the oscillatorian cyanobacterium Katagnymene accurata Geitler (for the first time found in Poland), and green algae Coenochloris sphagnicola Hindák, Mucidosphaerium sphagnale (Hindák) C. Bock, Pröschold et Krienitz, Closterium navicula (Bréb.) Lütkem., and Cosmarium cf. aphaerosporum var. corribense (W. et G.S. West) Krieger et Gerloff., which are described in more detail. As regards the species diversity, the plankton of the lake was rather species-poor in contrast to the algal communities in the Sphagnum littoral.
Published Online: 04 Jan 2015 Page range: 346 - 359
Abstract
Abstract
Four small-celled taxa are presented and described — Planothidium werumianum, P. pumilum, P. rhombiculum and P. rostratoholarcticum. Planothidium werumianum, P. pumilum and P. rhombiculum are proposed as new to science and P. rostratoholarcticum as a new name for Achnanthes lanceolata var. rostrata Hustedt 1911. The latter, coming from Germany, is transferred to Planothidium in the species rank. The new name — P. rostratoholarcticum — is necessary to avoid a junior homonym, i.e., Planothidium rostratum (Østrup) Lange-Bertalot 1999, a species described from tropical Thailand. The new taxa were compared to several other, more or less similar small-celled Planothidium spp., such as P. rostratum (Østrup) Lange-Bertalot, P. minutissimum (Krasske) Lange-Bertalot, P. granum (Hohn & Hellerman) Lange-Bertalot, P. daui (Foged) Lange-Bertalot, P. frequentissimum (Lange-Bertalot) Lange-Bertalot and P. engelbrechtii (Cholnoky) Round & Bukhtiyarova. Significant differences could be found through light- and electron microscopic fine structure analysis. Planothidium pumilum and P. rostratoholarcticum occur mainly in eutrophic alkaline rivers and lakes with medium to high conductivity, likewise in estuaries, lagoons, and backwater of the North Sea and the Baltic Sea. Planothidium werumianum and P. rhombiculum were found in small carbonate-rich rivers originating from medium altitude mountains.
Published Online: 04 Jan 2015 Page range: 360 - 365
Abstract
Abstract
The presented study describes the presence of fish fry in the diet of imagines of large Dytiscidae. The study was conducted between March and September in 2012 and 2013. A total of 163 large, aquatic, diving beetles were caught, which represented the following species: Dytiscus marginalis, Dytiscus circumcinctus, Cybister lateralimarginalis. Fish were identified by scales, bones, vertebrae, pharyngeal teeth. Insects were identified by epicrania, mandibles, hooks, limbs, body segments, eyes and wings. Crustaceans were identified by limbs and Oligochaeta by bristles. Seeds and eggs of invertebrates were found whole and intact. Fragments of fish fry were found in the digestive tracts of all three species collected in three studied ponds. The alimentary canals of the studied beetles contained also fragments of insects, detritus, plant tissue, Crustacea, Arachnida, other invertebrates, Oligochaeta, and Gastropoda.
Published Online: 04 Jan 2015 Page range: 366 - 373
Abstract
Abstract
The occurrence and the distribution of potentially human pathogenic bacteria such as Aeromonas, Pseudomonas aeruoginosa, Staphylococcus and Vibrio-like organisms in the sand and the adjacent seawater of the recreational coastal beach were studied. The highest mean number among these four studied groups of bacteria was represented by Aeromonas-like organisms and the lowest one by Staphylococcus-like organisms. Dry sand was inhabited by the highest number of all studied potentially pathogenic bacteria. Within a year, the number of the studied bacteria inhabiting the sand and the seawater showed considerable monthly changes. There were differences in the abundance of potentially pathogenic bacteria between the surface and the subsurface sand layers with a clear decrease in their number toward the deeper layers of the sand.
Published Online: 04 Jan 2015 Page range: 374 - 380
Abstract
Abstract
The aim of the present work conducted in the area of Międzyrzeki Strict Nature Reserve in the Roztocze National Park was to show new sites of rare and species new to Poland from the Kobayasiella genus (K. okadae (Skvortzov) Lange-Bert., K. tintinnus Buczkó, Wojtal & Jahn) with regard to morphological and ecological characteristics. Chemical parameters show that investigated habitats are poor and oligotrophic with a low content of chlorides, sulfates and nitrates. K. okadae, K. subtilissima (Cleve) Lange-Bert. and K. tintinnus were found in the studied area. The authors suggest the use of synonym Navicula hoeflerii Cholnoky for the Kobayasiella okadae. LM and SEM images were used in the analysis of the material.
Published Online: 04 Jan 2015 Page range: 381 - 392
Abstract
Abstract
The aim of this study was to determine the spatial and temporal variation of phytoplankton and water quality in response to the hydrological regime in an isolated floodplain lake (North Mollaköy Lake) of the Sakarya River. Variations in the composition, biomass and functional groups of phytoplankton and environmental parameters were monthly analyzed in sub-surface samples collected from the pelagic zone at four stations from July 2012 to June 2013. A total of 109 taxa were identified, and the species which contributed the most to the phytoplankton biomass were grouped into 14 functional groups (FGs). The distribution of FGs was linked to the transition (T1 and T2), high (HW) and low (LW) water periods in North Mollaköy Lake. FGs J, MP, N, G, X1, X2, Y, W1, W2, S1, H1, B and C were the contributors to the phytoplankton biomass during the low-water period (LW) and the transition periods (T1 and T2), while Lo contributed the most during the high-water period (HW). RDA revealed that the most important factor affecting the temporal distribution of FGs was the water discharge and that there are some differences between stations in terms of Si, pH values and the distribution of FGs.
Published Online: 04 Jan 2015 Page range: 393 - 401
Abstract
Abstract
Simonsenia delognei is a diatom species which is relatively rarely recorded, but apparently widespread in Europe and other continents. This taxon has recently been discovered for the first time in springs of Central Poland, where it was found to occur abundantly. Somewhat later this species has also been identified and photographed in samples from the Eagean Region in Turkey. Light and electron microscopic studies were carried out on S. delognei populations from the Quaternary spring located near Łódź (Central Poland) and from the Porsuk and Felent Rivers and a spring in the Türkmen Mountains in Kütahya and Havuzdere Stream in Yalova (NW Turkey). Morphological studies were accompanied by environmental measurements and determination of changes in the seasonal distribution of S. delognei in a key area, i.e. the Porzeczkowe spring in Central Poland, which are included in the present study. Identification of S. delognei under a light microscope is difficult and hence an electron microscope is required for accurate taxonomic identification.
Published Online: 04 Jan 2015 Page range: 402 - 417
Abstract
Abstract
Macroinvertebrates were sampled in the lowland Drzewiczka River downstream from a dam reservoir and just below a whitewater slalom canoeing track. For over 20 years, pulse flow fluctuations of moderate intensity, an effect of two-three hour long releases of water per day to enable training of canoeists, induced a patchy mosaic in the tailwater riverbed compared to a natural site. After these regular disturbances, three accidental events of increased discharge of different magnitudes (three, five and sixteen times higher compared to a long-term median) occurred in two following years and we were able to investigate their impact on the habitat-specific processes.
Two of the three events (in September 2000 and March 2001) had a minor effect on abiotic and biotic variables, while the third one (in February 2002, over 40 m3 s−1 discharge) destabilized the bed habitat, washing away the flood-sensitive macroinvertebrates of Ephemeroptera and Trichoptera. In the dominant benthic group, i.e. Chironomidae, varied resistance patterns were observed, depending on their mode of life and patch occupancy. In conclusion, biota in the Drzewiczka River have adapted their life history to long-term moderate flow disturbance, but the largest flood mobilized bed sediments together with most of their dwellers.
Published Online: 04 Jan 2015 Page range: 418 - 426
Abstract
Abstract
Large numbers of Mallard Anas platyrhynchos (max. 10,490 ind.), Black-headed Gull Chroicocephalus ridibundus (max. 3,430 ind.) and Great Cormorant Phalacrocorax carbo (max. 1,449 ind.) were recorded on the Goczałkowice Reservoir, Poland (2,754 ha). Most of the waterbirds occurred in the backwater of this reservoir. The amount of phosphorus and nitrogen loaded by the most numerous waterbirds into Goczałkowice Reservoir was estimated at 958 kg and 2,621 kg, respectively in 2011 and 1,043 kg and 2,793 kg, respectively in 2012. In 2011 and 2012, the waterbirds introduced a considerable amount of phosphorus, nitrogen and a large number of coliforms into the backwater of the reservoir. The concentration of different forms of phosphorus and nitrogen, chlorophyll-a and bacteria coli in the water was not greater at the site of birds’ concentration (except dissolved organic nitrogen). The concentration of nitrates in the water at the site near the breeding colony of gulls in comparison with the reference site was not different. The amounts of P-tot and N-tot in the sediment were similar at the site affected by waterbirds and at the reference site. The dynamics of water masses was not the reason for the lack of differences between the studied sites.
Published Online: 04 Jan 2015 Page range: 427 - 430
Abstract
Abstract
The present paper reports on the occurrence of the Atlantic rangia Rangia cuneata in the Wisła Śmiała River (coastal waters of the Gulf of Gdańsk, the southern Baltic Sea) from around 2012–2014.
Published Online: 04 Jan 2015 Page range: 431 - 435
Abstract
Abstract
The present paper reports for the first time on the occurrence of the oriental shrimp Palaemon macrodactylus M. J. Rathbun, 1902 in the coastal waters of the Baltic Sea in 2014. Ovigerous females and young individuals were found, indicating a possible establishment of this species in the Baltic Sea.
Published Online: 04 Jan 2015 Page range: 436 - 441
Abstract
Abstract
Abundance, biomass, and taxonomic composition of the ciliate community were studied in the surface waters along a transect between 50°S 61°W and 48°N 5°W (Atlantic Ocean, March-April 2011). The abundance of heterotrophic ciliates was low in the equatorial zone (280–320 cells l−1, 0.11–0.12 μg C l−1), but it increased toward both the northern and southern temperate zones with the maximum abundance observed at 44°S (2667 cells l−1, 0.82 μg C l−1). This pattern resembles the global distribution of oceanic primary production, which is low at lower latitudes and high in temperate zones. In temperate zones ciliate abundance peaks during spring and fall. Thus, because the present study was carried out during spring in the northern hemisphere and austral fall in the southern hemisphere, the ciliate abundance at higher latitudes was additionally elevated. Functionally autotrophic Mesodinium rubrum was only observed in the northern hemisphere and tropical waters. Its maximum abundance was observed at 48°N (1080 cells l−1, 1.14 μg C l−1). The most frequently observed ciliates were oligotrichs and choreotrichs. Other important ciliates were haptorids (including M. rubrum) and hypotrichs.
Published Online: 04 Jan 2015 Page range: 442 - 449
Abstract
Abstract
Cylindrospermopsin (CYN) is a cytotoxin produced by several species of cyanobacteria, which occur all over the world. It was demonstrated that CYN has a wide spectrum of biological activity in animal cells, involving hepatotoxicity, genotoxicity, cytotoxicity and carcinogenic potential, and is considered as one of the factors that caused human poisoning in Palm Island (Australia) and in Caruaru (Brazil). This compound may be introduced into organism by several ways, including consumption of water, fishes and seafood as well as accidental swallowing or aerosol spray inhalation during recreational using of reservoirs covered by cyanobacterial blooms. The information about the CYN impact on environment and its degradation processes under natural conditions is scant. Taking this into consideration CYN should be regarded as a potential threat to human health and life. This review presents physicochemical characteristic and biological activity of CYN, occurrence in freshwaters and its sensitivity to the influence of some environmental factors.
Freshwater green algal biofouling of boats refers to the accrual of freshwater green algae on boats immersed in water. The current research focused on the morphological characteristics of the isolates, species ecology, and the physicochemical properties of the water at the sampling sites. Two localities, Haji Zai and Sardaryab, were sampled at the Kabul River in the district of Charsadda, Pakistan. Freshwater green algae causing biofouling were isolated from the boats. A total of three genera: Cladophora, Rhizoclonium, and Spirogyra with fifteen species belonging to the families Cladophoraceae and Zygnemataceae were observed. Statistical analysis reveals significant stimulation of green algal species in the boats’ fouled communities by increases in water temperature, conductivity, and Total Suspended Solids (TSS). The algal growth at the Haji Zai site is suppressed by TDS in autumn (Pearson −0.56) and is stimulated by water temperature in spring (Pearson 0.44). At the Sardaryab site, algae were stimulated in spring by pH of water (Pearson 0.61), and suppressed by Total Dissolved Solids (TDS) in autumn (Pearson −0.43). Statistical analysis indicates that pH, conductivity, and temperature are the main factors determining the algal biofouling in the Kabul River.
Microflora of cyanobacteria and algae of small forest dystrophic Lake Sęczek located in the Masurian Lake District, NE Poland, was investigated in 2012 and 2013. A total of 16 genera with 7 species of cyanobacteria and 56 genera with 74 species, 6 varietas and forms of algae were determined. Most of them represented commonly occurring microorganisms of slightly acidic waters, but some of them are considered rare, i.e. the oscillatorian cyanobacterium Katagnymene accurata Geitler (for the first time found in Poland), and green algae Coenochloris sphagnicola Hindák, Mucidosphaerium sphagnale (Hindák) C. Bock, Pröschold et Krienitz, Closterium navicula (Bréb.) Lütkem., and Cosmarium cf. aphaerosporum var. corribense (W. et G.S. West) Krieger et Gerloff., which are described in more detail. As regards the species diversity, the plankton of the lake was rather species-poor in contrast to the algal communities in the Sphagnum littoral.
Four small-celled taxa are presented and described — Planothidium werumianum, P. pumilum, P. rhombiculum and P. rostratoholarcticum. Planothidium werumianum, P. pumilum and P. rhombiculum are proposed as new to science and P. rostratoholarcticum as a new name for Achnanthes lanceolata var. rostrata Hustedt 1911. The latter, coming from Germany, is transferred to Planothidium in the species rank. The new name — P. rostratoholarcticum — is necessary to avoid a junior homonym, i.e., Planothidium rostratum (Østrup) Lange-Bertalot 1999, a species described from tropical Thailand. The new taxa were compared to several other, more or less similar small-celled Planothidium spp., such as P. rostratum (Østrup) Lange-Bertalot, P. minutissimum (Krasske) Lange-Bertalot, P. granum (Hohn & Hellerman) Lange-Bertalot, P. daui (Foged) Lange-Bertalot, P. frequentissimum (Lange-Bertalot) Lange-Bertalot and P. engelbrechtii (Cholnoky) Round & Bukhtiyarova. Significant differences could be found through light- and electron microscopic fine structure analysis. Planothidium pumilum and P. rostratoholarcticum occur mainly in eutrophic alkaline rivers and lakes with medium to high conductivity, likewise in estuaries, lagoons, and backwater of the North Sea and the Baltic Sea. Planothidium werumianum and P. rhombiculum were found in small carbonate-rich rivers originating from medium altitude mountains.
The presented study describes the presence of fish fry in the diet of imagines of large Dytiscidae. The study was conducted between March and September in 2012 and 2013. A total of 163 large, aquatic, diving beetles were caught, which represented the following species: Dytiscus marginalis, Dytiscus circumcinctus, Cybister lateralimarginalis. Fish were identified by scales, bones, vertebrae, pharyngeal teeth. Insects were identified by epicrania, mandibles, hooks, limbs, body segments, eyes and wings. Crustaceans were identified by limbs and Oligochaeta by bristles. Seeds and eggs of invertebrates were found whole and intact. Fragments of fish fry were found in the digestive tracts of all three species collected in three studied ponds. The alimentary canals of the studied beetles contained also fragments of insects, detritus, plant tissue, Crustacea, Arachnida, other invertebrates, Oligochaeta, and Gastropoda.
The occurrence and the distribution of potentially human pathogenic bacteria such as Aeromonas, Pseudomonas aeruoginosa, Staphylococcus and Vibrio-like organisms in the sand and the adjacent seawater of the recreational coastal beach were studied. The highest mean number among these four studied groups of bacteria was represented by Aeromonas-like organisms and the lowest one by Staphylococcus-like organisms. Dry sand was inhabited by the highest number of all studied potentially pathogenic bacteria. Within a year, the number of the studied bacteria inhabiting the sand and the seawater showed considerable monthly changes. There were differences in the abundance of potentially pathogenic bacteria between the surface and the subsurface sand layers with a clear decrease in their number toward the deeper layers of the sand.
The aim of the present work conducted in the area of Międzyrzeki Strict Nature Reserve in the Roztocze National Park was to show new sites of rare and species new to Poland from the Kobayasiella genus (K. okadae (Skvortzov) Lange-Bert., K. tintinnus Buczkó, Wojtal & Jahn) with regard to morphological and ecological characteristics. Chemical parameters show that investigated habitats are poor and oligotrophic with a low content of chlorides, sulfates and nitrates. K. okadae, K. subtilissima (Cleve) Lange-Bert. and K. tintinnus were found in the studied area. The authors suggest the use of synonym Navicula hoeflerii Cholnoky for the Kobayasiella okadae. LM and SEM images were used in the analysis of the material.
The aim of this study was to determine the spatial and temporal variation of phytoplankton and water quality in response to the hydrological regime in an isolated floodplain lake (North Mollaköy Lake) of the Sakarya River. Variations in the composition, biomass and functional groups of phytoplankton and environmental parameters were monthly analyzed in sub-surface samples collected from the pelagic zone at four stations from July 2012 to June 2013. A total of 109 taxa were identified, and the species which contributed the most to the phytoplankton biomass were grouped into 14 functional groups (FGs). The distribution of FGs was linked to the transition (T1 and T2), high (HW) and low (LW) water periods in North Mollaköy Lake. FGs J, MP, N, G, X1, X2, Y, W1, W2, S1, H1, B and C were the contributors to the phytoplankton biomass during the low-water period (LW) and the transition periods (T1 and T2), while Lo contributed the most during the high-water period (HW). RDA revealed that the most important factor affecting the temporal distribution of FGs was the water discharge and that there are some differences between stations in terms of Si, pH values and the distribution of FGs.
Simonsenia delognei is a diatom species which is relatively rarely recorded, but apparently widespread in Europe and other continents. This taxon has recently been discovered for the first time in springs of Central Poland, where it was found to occur abundantly. Somewhat later this species has also been identified and photographed in samples from the Eagean Region in Turkey. Light and electron microscopic studies were carried out on S. delognei populations from the Quaternary spring located near Łódź (Central Poland) and from the Porsuk and Felent Rivers and a spring in the Türkmen Mountains in Kütahya and Havuzdere Stream in Yalova (NW Turkey). Morphological studies were accompanied by environmental measurements and determination of changes in the seasonal distribution of S. delognei in a key area, i.e. the Porzeczkowe spring in Central Poland, which are included in the present study. Identification of S. delognei under a light microscope is difficult and hence an electron microscope is required for accurate taxonomic identification.
Macroinvertebrates were sampled in the lowland Drzewiczka River downstream from a dam reservoir and just below a whitewater slalom canoeing track. For over 20 years, pulse flow fluctuations of moderate intensity, an effect of two-three hour long releases of water per day to enable training of canoeists, induced a patchy mosaic in the tailwater riverbed compared to a natural site. After these regular disturbances, three accidental events of increased discharge of different magnitudes (three, five and sixteen times higher compared to a long-term median) occurred in two following years and we were able to investigate their impact on the habitat-specific processes.
Two of the three events (in September 2000 and March 2001) had a minor effect on abiotic and biotic variables, while the third one (in February 2002, over 40 m3 s−1 discharge) destabilized the bed habitat, washing away the flood-sensitive macroinvertebrates of Ephemeroptera and Trichoptera. In the dominant benthic group, i.e. Chironomidae, varied resistance patterns were observed, depending on their mode of life and patch occupancy. In conclusion, biota in the Drzewiczka River have adapted their life history to long-term moderate flow disturbance, but the largest flood mobilized bed sediments together with most of their dwellers.
Large numbers of Mallard Anas platyrhynchos (max. 10,490 ind.), Black-headed Gull Chroicocephalus ridibundus (max. 3,430 ind.) and Great Cormorant Phalacrocorax carbo (max. 1,449 ind.) were recorded on the Goczałkowice Reservoir, Poland (2,754 ha). Most of the waterbirds occurred in the backwater of this reservoir. The amount of phosphorus and nitrogen loaded by the most numerous waterbirds into Goczałkowice Reservoir was estimated at 958 kg and 2,621 kg, respectively in 2011 and 1,043 kg and 2,793 kg, respectively in 2012. In 2011 and 2012, the waterbirds introduced a considerable amount of phosphorus, nitrogen and a large number of coliforms into the backwater of the reservoir. The concentration of different forms of phosphorus and nitrogen, chlorophyll-a and bacteria coli in the water was not greater at the site of birds’ concentration (except dissolved organic nitrogen). The concentration of nitrates in the water at the site near the breeding colony of gulls in comparison with the reference site was not different. The amounts of P-tot and N-tot in the sediment were similar at the site affected by waterbirds and at the reference site. The dynamics of water masses was not the reason for the lack of differences between the studied sites.
The present paper reports on the occurrence of the Atlantic rangia Rangia cuneata in the Wisła Śmiała River (coastal waters of the Gulf of Gdańsk, the southern Baltic Sea) from around 2012–2014.
The present paper reports for the first time on the occurrence of the oriental shrimp Palaemon macrodactylus M. J. Rathbun, 1902 in the coastal waters of the Baltic Sea in 2014. Ovigerous females and young individuals were found, indicating a possible establishment of this species in the Baltic Sea.
Abundance, biomass, and taxonomic composition of the ciliate community were studied in the surface waters along a transect between 50°S 61°W and 48°N 5°W (Atlantic Ocean, March-April 2011). The abundance of heterotrophic ciliates was low in the equatorial zone (280–320 cells l−1, 0.11–0.12 μg C l−1), but it increased toward both the northern and southern temperate zones with the maximum abundance observed at 44°S (2667 cells l−1, 0.82 μg C l−1). This pattern resembles the global distribution of oceanic primary production, which is low at lower latitudes and high in temperate zones. In temperate zones ciliate abundance peaks during spring and fall. Thus, because the present study was carried out during spring in the northern hemisphere and austral fall in the southern hemisphere, the ciliate abundance at higher latitudes was additionally elevated. Functionally autotrophic Mesodinium rubrum was only observed in the northern hemisphere and tropical waters. Its maximum abundance was observed at 48°N (1080 cells l−1, 1.14 μg C l−1). The most frequently observed ciliates were oligotrichs and choreotrichs. Other important ciliates were haptorids (including M. rubrum) and hypotrichs.
Cylindrospermopsin (CYN) is a cytotoxin produced by several species of cyanobacteria, which occur all over the world. It was demonstrated that CYN has a wide spectrum of biological activity in animal cells, involving hepatotoxicity, genotoxicity, cytotoxicity and carcinogenic potential, and is considered as one of the factors that caused human poisoning in Palm Island (Australia) and in Caruaru (Brazil). This compound may be introduced into organism by several ways, including consumption of water, fishes and seafood as well as accidental swallowing or aerosol spray inhalation during recreational using of reservoirs covered by cyanobacterial blooms. The information about the CYN impact on environment and its degradation processes under natural conditions is scant. Taking this into consideration CYN should be regarded as a potential threat to human health and life. This review presents physicochemical characteristic and biological activity of CYN, occurrence in freshwaters and its sensitivity to the influence of some environmental factors.