3.1. Geographical Distribution of Algal Blooms in Russia
The analysis of the geographical distribution of algal bloom cases shows that they occur in all major climate zones of Russia from polar to warm temperate and arid (Figure 1
). Algal blooms were observed in freshwater and marine water bodies, both in the European and Asian part of the Russian Federation.
The largest number of algal outbreaks among the federal districts of the Russian Federation in 2016–2018 (Figure 2
) was reported in the Southern Federal District (21%). It is a densely populated region with the warmest climate and developed agriculture. The Central and Volga (18% and 15%) Federal Districts were in the second and third places, respectively. These regions are also densely populated and have developed industry and agriculture. Besides, we cannot exclude a possibility that the local population and mass media in these regions are more concerned about the problem of algal blooms that results in a higher number of reports. Algal blooms were also observed in regions with a colder climate and lower population density: Northwestern (11%), Ural (10%), Siberian (11%), and Far Eastern Federal Districts (12%). The smallest number of reports on algal blooms was recorded in the North Caucasus Federal District (1%). This fact can be explained by the mountainous terrain with a high flow rate in rivers and water bodies or by a lack of significant public awareness about the problem of eutrophication.
We analyzed the correlation between the number of algal blooms in federal districts and regions of the Russian Federation in 2016–2018 and various statistical indicators (average resident population, arable land, inorganic and organic fertilizers used by agricultural organizations, and livestock numbers including cows, pigs, and poultry) (Table S1, Table S2
). The Shapiro–Wilk test showed that all variables had a normal distribution except for the number of pigs in farms that was excluded from the further analysis. However, we did not find a reliable relationship between the number of algal blooms and the analyzed parameters using the Pearson correlation method. The correlation range was from 0.13 to 0.63, while the p-value was in the range 0.09–0.74.
3.2. Description of Outbreaks in Mass-Media
The analysis of media reports showed that the expert estimates by scientists are given in 26% of cases. In a large number of cases (43%), the opinion of government officials (Prosecutor’s office, Federal Service for the Supervision of Natural Resources, Federal Service on Surveillance for Consumer Rights Protection and Human Well-being, municipal and regional authorities) is given.
Most of the water bodies for which information on the algal blooms was obtained were small in size. Their share was 59% of the total number of cases. Large reservoirs for which satellite analysis methods are applicable accounted for 41% of the sample. Previous outbreaks in the same reservoir are mentioned in 22% of cases, indicating the recurrence of the problem.
In 76% of cases, the possible causes of algal blooms are given. In most cases, the anthropogenic factors are mentioned as the main cause of algal outbreaks (42%). Among them, the focus was on effluents from municipal treatment facilities (18%). Effluents from industrial enterprises account for 16%, effluents from agriculture or tourism each comprise 4%. Natural causes are less frequently mentioned than anthropogenic ones (29% of cases). Among the natural causes, the hot weather (15%) and shallowing of the reservoir (13%) are noted.
The analysis of media reports shows that the dominant types of photosynthetic organisms were named in 70% of cases. Moreover, the largest number of references was associated with cyanobacteria (40% cases). The references on the outbreak of macrophytes are in second place. Some reports cited interviews with scientists. In these cases, the articles may have provided information on taxonomic groups of microalgae and cyanobacteria. According to these reports, in freshwater reservoirs the cyanobacterial growth of the genera Microcystis, Anabaena, Aphanizomenon
, and Dolichospermum
was reported to cause the greatest problem. These genera dominated in algal blooms registered in пресноводных водоемах в different regions of Russia. The outbreak of Alexandrium
microalgae was detected in the Pacific Ocean. The mass media reported also about Nodularia
cyanobacterial blooms in the Baltic Sea. Also, a unique case was recorded in 2018 in the village of Syreika, Samara Region. An outbreak of purple sulfur bacteria Thiolamprovum
sp. occurred in artificial storage ponds near an industrial area comprised by several brewing companies [42
3.3. Reported Effects of Algal Blooms
The media coverage mainly concerns the social consequences of the eutrophication of water bodies (72% of cases). First of all, the poor quality of water is mentioned, causing unwillingness (18%) or an inability to swim in the reservoir (9%). A relatively high number of cases (16%) express concern over the possible presence of toxins in the water. The third group of negative consequences of algal blooms attracting the attention of the media is a decrease in the tap water quality (15%) or the cessation of water supply to the population (2%), as well as a bad smell from the reservoir (11%).
The negative environmental consequences of eutrophication of water bodies are mentioned less often than social problems (35% of cases). Mainly they refer to the problems associated with the death of fish or birds (33%). It should be noted that the death of fish or birds in many cases becomes the main fact that the media draws attention to and is often mentioned in the article headings. Among the environmental consequences, flooding of part of the territory caused by clogging of drainage pipes with algae is also reported.
Economic losses caused by the outbreaks of algae are mentioned in 20% of cases. Basically, losses are estimated as direct costs associated with the reconstruction of obsolete water supply and wastewater treatment systems.
Only 30% of cases mention any measures taken to solve the problem of algal blooms in reservoirs. Among them, 13% of cases mention the necessity to take measures, 4% provide information on planning the measures to solve the problem, and 13% of cases report about actual events.
3.4. Description of Outbreaks in Scientific Articles
We have found references to only 11 cases of algal outbreaks in the reservoirs of Russia in 2016–2018 in the scientific articles [44
]. In that time, four cases happened in 2016, six in 2017. Only one report presented on a conference described an outbreak in 2018 [48
]. This distribution is probably due to the fact that the preparation of a research article takes much more time than the communication in mass media. A small number of scientific articles does not yet allow us to directly compare the data obtained from mass media analysis and from scientific articles. Nevertheless, some preliminary conclusions can be drawn.
The majority of articles (10 out of 11) focused on the cyanobacteria dominated blooms in freshwater reservoirs and the mediterranian Baltic and Azov Seas with relatively low salinity level [45
]. Planktothrix agardhii, Planktolyngbya limnetica, Aphanizomenon flos-aquae, Microcystis aeruginosa, Dolichospermum spiroides,
and Dolichospermum lemmermanii
were noted among the dominating species in freshwater reservoirs. The cyanobacterium Nodularia spumigena
dominated in the bloom in the Baltic Sea. Besides, the colonies of Anabena sp., Merismopedia sp, Planktothrix sp.,
and Aphanizomenon flos-aquae
were detected [48
]. One article focused on “Red tide” events that happened next to the Pacific coast on the Far East of Russia with a dinoflagellate Alexandrium fundyense
as a dominant species [44
]. According to the opinion of the authors of scientific articles, the main reasons for the outbreaks were natural phenomena, e.g., hot weather and changes in hydrodynamic characteristics of the reservoirs (5 out of 11). Anthropogenic causes (contaminated wastewater flow) were mentioned in 2 cases out of 11.
The determination of toxins concentration was conducted in three cases [44
]. On August 2016, the algal bloom and the mass mortality of fish (gibel carp Carassius gibelio
) and waterfowl (mallard Anas platyrhynchos
) were detected in the Kazanka River (the tributary of the Volga River). The cyanobacteria Planktolyngbya limnetica
and Aphanizomenon flos-aquae
dominated in the samples. The content of cyanotoxins in water according to the results of ELISA was 1.4–12.1 μg/L (microcystins) and 0.057–0.294 μg/L (anatoxin-a). The content of microcystins (1.96–3.16 μg/kg) and anatoxin-a (1.56–5.21 μg/kg) in fish and duck muscles were also determined [46
In September 2017, the area of discolored water 50 m wide and 30 m long was found close to the dam of the Irkutsk hydroelectric power station near Lake Baikal. Analysis of samples showed that discolored water was a result of a Dolichospermum lemmermannii
bloom, followed by its decay and release of saxitoxin and nutrients. sxtA gene was amplified from the samples. Water from the polluted area contained 600 ± 100 μg/L saxitoxin as measured by HPLC-MS (Agilent technologies, Inc., CA, USA). Immunoassay analysis (ELISA) showed a concentration of saxitoxins in the water of 2900 ± 900 μg/L [47
In July 2017 a red tide occurred in Olyutorskiy Bay, Bering Sea. Fishermen reported that the pink salmons (Oncorhynchus gorbuscha
) caught in the bloom area were slack, looked tired and died soon in the trap net. The water samples contained a suspension of Alexandrium
cells. The concentration of saxitoxin determined using an immune-enzyme assay (test-system RIDASCREEN®
FAST PSP SC) reached 330 μg/L [44
The main negative effects mentioned in the scientific articles are foul smell of the water (3 cases out of 11), toxins presence in water (3 cases out of 11), fish and bird kill (2 out of 11), unwillingness to swim in a reservoir (1 case) and deterioration of tap water quality (1 case).
It should be noted that in 3 cases out of 11 the scientific articles mentioned the direct appeal to the scientists by the representatives of the society or business. Among them there were the appeals of Irkutsk hydroelectric power station administration concerned by the risk of contaminated water flow into the urban water system, as well as the appeals of the fishermen worried by the unusual behavior of pink salmon [44
]. Besides, the reason for the scientific research may be the appeal of the local environmental authorities as a result of the population’s concern about the water color change in the reservoir [50
]. In some cases, there was no mention about the local population requests or information from mass media in the scientific publication, but actually the research was initiated by the information from the community: for example, the authors of this article took part in the Dolichospermum lemmermannii
bloom study on Lake Baikal in 2016 [54
]. The information about the bloom came to the authors through several channels, including the direct appeal of the local residents, mass media, and social networks. However, the article describing the bloom contains only the mention that “cyanobacterial bloom of a green color a few kilometers in size with a bad odor was discovered by local people”, but no particular way of the information transfer is given [54