Odra

The report of the Team for the Situation Arising on the Oder River

The document is available in electronic form on the website of the Institute of Environmental Protection – National Research Institute.

A team of 49 scientists from renowned state research institutes and universities analysed tens of thousands of research results and 200 items of foreign literature. The experts analysed satellite images and other available research material from before the mass fish die-off and when the phenomenon was observed in the river. The report prepared by the Team consists of expert scientific opinions, together with research results. The document contains in-depth analyses, findings to date and recommendations. It was edited by Agnieszka Kolada, PhD, from the Institute of Environmental Protection - National Research Institute, who presented the results on 29 September 2022 during a conference summarising the Team's work. The document was published on 30 September 2022. The Report of the Team for the Situation Arising on the Oder River, appointed by the Minister of Climate and Environment, is the basis for further directional research to clarify the causes of the catastrophe.

The main clue - Prymnesium parvum

After the catastrophe in the Oder River, emergency monitoring was launched to collect daily samples. They were taken at 37 points distributed along the entire length of the river. By 20 September, more than 20 000 tests had been made, and monitoring is still ongoing

- explained Agnieszka Kolada, PhD, from the Institute of Environmental Protection - National Research Institute. After cyclical, daily changes in water oxygenation were observed, an algal bloom was suspected. Following the exclusion of the most common species in our country, samples were sent for further analysis to the scientific laboratory at the Inland Fisheries Institute in Olsztyn.

In August, scientists found the presence of the microalgae Prymnesium parvum, the so-called 'golden algae'. These are rare microscopic algae that typically live in marine coastal waters but adapt to river conditions, especially in industrial areas with increased salinity, in farm ponds and other shallow bodies of water. 'Golden algae' is a species still poorly understood by scientists. Procedures for monitoring water for Prymnesium parvum are not found in EU recommendations or in the recommendations of the Baltic Marine Environment Protection Commission (HELCOM), which was set up to monitor water status.

The appearance of mass microalgae blooms along the entire length of a large river such as the Oder is surprising for scientists but not the only one observed so far. Blooms of Prymnesium parvum have already occurred in rivers and reservoirs and marine waters on all continents except Antarctica. Massive golden algae blooms are experienced in the USA and waters in China, Israel and Australia. In Europe, 'golden algae' have been recognised since the 1920s in the Netherlands, among others. In 1990, a Prymnesium parvum bloom and fish die-off were observed in the Botshol reserve, Utrecht, consisting of two shallow lakes, ditches and reed beds created by peat extraction in the 17th century.

Mass fish die-offs due to the 'golden algae' bloom were also reported in Norway, where 750 tonnes of farmed fish were harvested. Interestingly, a 'golden algae' bloom does not always indicate the presence of ichthyotoxins lethal to fish and other organisms with gills. The production of prymnesins by the algae occurs in certain situations, such as a sudden change in water parameters, which include an increase as well as a decrease in salinity. However, no strictly defined boundary conditions exist in Europe or worldwide at which a bloom occurs. There are also no precise research benchmarks for fish-killing prymnesins.

Polish scientists are conducting pioneering research on‘golden algae’ toxins

The presence of large quantities of ichthyotoxins in samples taken from the Oder and the Canal Gliwice in September 2022 was found by experts from the University of Gdańsk. The results were confirmed by analyses carried out by the laboratory of the University of Vienna. During further work, scientists from the University of Gdańsk have isolated the DNA and RNA of the prymnesins. The researchers are currently developing a standard to determine these little-known ichthyotoxins precisely. The European Union does not yet have research standards in this area. Examining prymnesins will allow a more accurate determination of the conditions under which toxins may be released. It will also help identify the likelihood of 'golden algae' blooms in inland waters.

It is now known that the phenomenon is favoured by high temperatures and sunshine, increased water salinity and low water flow - Prymnesium parvum, like other algae, is particularly likely to proliferate in shallow, standing shallow, standing or slow-moving waters.

In the Oder River, fish die-offs were cyclical - at time intervals and in different locations

According to the scientists' findings, fish die-off in the Oder River was not a continuous but cyclical process. It was observed not only in the river's current but also in bodies of water linked to the Oder, such as Lake Baikal, and in oxbow lakes, stagnant pools and canals that meet the Oder, including the Gliwice Canal.

From the end of July to 12 September, 249 tonnes of dead fish were collected in five voivodeships

- explained Agnieszka Kolada, PhD, from the Institute of Environmental Protection.

In turn, toxicological tests for more than 300 substances, including heavy metals, ruled out pollution as a cause of the mass die-off in the Oder. It also ruled out salting due to bacteria, viruses and parasites. The results of the study are available in the report

- Agnieszka Kolada, PhD, said.

The fish studied had acute damage to the organs with the strongest blood supply, which is critical information. The image of these tissues indicated a rapid death due to some fast-acting agent. It was not a prolonged exposure, and there must have been some violent environmental changes that gave such an image of the tissues

- an expert from the Institute of Environmental Protection - National Research Institute noted.

The disruption of haematopoietic processes and damage to the gills is most likely related to the effects of haemolytic toxins

- Agnieszka Kolada, PhD, explained.

It has given rise to the hypothesis of a toxic effect of the ‘golden algae’

- she stressed.

Special hydrological and meteorological conditions in the summer of 2022

Hot weather and very high insolation favoured a massive microalgal bloom, which exceeded standards by 30% in July 2022. The water temperature in the Oder River averaged 27 oC. The high temperatures and additionally the lack of rainfall contributed to changes in water parameters, including an increase in salinity levels.

There was no significant rainfall in June and July, resulting in a low water level of the river

- Agnieszka Kolada, PhD, said.

The flows were also very low, meaning that the water in the river was almost constant, which is of great importance for water quality. The same load of substances entering the river when the water level is low will manifest itself in much higher concentrations

- the expert pointed out. The analyses of conductivity, concentration of chlorides, pH of the water during the disaster confirm the phenomenon.

It should be remembered that the Oder is a river with a poor ecological state, flowing through industrial areas. The salinity in places, especially the canals in Silesia, which are connected to the river, is close to the values recorded in the Baltic Sea. However, it is worth pointing out that the state of the water, in terms of quality in 2022, did not differ from the monitoring data that have been characteristic of this river for years

- noted Agnieszka Kolada., PhD.

The scientists conducting the analyses within the Team did not find any factors besides the existing ones that could lead to a mass die-off of fish and mussels in the Oder. The scientific evidence gathered so far indicates that the catastrophe in the Oder River was caused by a massive bloom of the microalgae Prymnesium parvum, which produced fish-killing toxins. The phenomenon was facilitated by specific hydrological and meteorological conditions, which contributed to a change in the parameters of the water. Also supporting the thesis of the effect of ichthyotoxins is that in the Oder River, only aquatic organisms with gills were dying en masse.

The experts concluded that there were grounds to state that in 2022 all the conditions favoured the mass bloom of an invasive, alien microalgal species to form. According to the scientists, there is also a risk that a mass bloom of 'golden algae' on the Oder will recur. It is also possible that Prymnesium parvum to other lake rivers in Poland. Therefore, the expert team analysed methods of combating 'golden algae' used in other countries. Subsequent analyses in this direction are planned.

During the work of the Team for the Situation Arising on the Oder River, the Inspectorate of Environmental Protection also inspected the Vistula. The ‘golden algae’ was not found in its waters.

Water quality monitoring and research work continues

Despite the presence of 'golden algae' along the entire length of the Oder, in its oxbow lakes and some canals, other factors that may have led to mass die-offs of aquatic organisms are still being considered. Research work is therefore continued. At this stage, however, individual threads will be investigated directionally by specialised teams and units. The laboratory of the University of Gdańsk continues its genetic research into 'golden algae' and the toxins they produce. The Inland Fisheries Institute - National Research Institute still researches 'golden algae.' Environmental services, in turn, continue to inspect the water permits of entities that discharge into the Oder River and are analysing the collected documentation.

The ‘golden algae’ that have appeared in the Oder River pose no immediate threat to the 2 million inhabitants of the towns and cities along the Oder. Nor are they dangerous for livestock, wild mammals and fish-eating birds. However, they threaten aquatic ecosystems, which translates into the overall health of the environment. Therefore, directional research is continued, and the situation is clarified in detail.

Recommendations of the Team for the Situation Arising on the Oder River experts

Having analysed the situation on the Oder River, the expert team recommends solutions in its summary to reduce the risk of a repeat of a disaster of a similar magnitude to the one in 2022. The recommendations include:

• Establishing a system for continuously measuring water quality for selected parameters, with access to online data for all stakeholders, including monitoring parameters linked to blooms and monitoring of the ‘golden algae.’ The intelligent water catchment management system should use both terrestrial and satellite data. Priority should be given to water bodies where water parameters conducive to blooms are recorded. Ensuring the organisational and financial conditions for the continuous operation of the system;
• Review and revision of existing permits for the discharge of wastewater into the waters in the Oder River basin, making the parameters and intensity of the discharge dependent on the current results of water tests, the introduction of an obligation to temporarily stop or limit discharges in emergencies reducing discharges in the event of an emergency;
• Improving the flow of information, implementing an early warning and response system, and streamlining crisis management procedures;
• Gradual recovery, based on the best expert knowledge of fish populations and other groups of organisms affected by the disaster.

Work on restoring the Oder fish population is already underway

Scientists from the Inland Fisheries Institute - National Research in Olsztyn have developed the assumptions of a recovery plan for restoring the Oder River ecosystems. The activities are divided into several stages carried out in a specific order. Among other things, the species inventory, relocation of surviving fish and collection of their genetic material to rebuild the Oder fish population are indispensable. It is essential to stock the river with species that previously existed and not alien species. It is also necessary to create the right habitat conditions for their existence, including the formation of so-called refugia, i.e. places where fish can take refuge if there are substances in the water that could threaten them. A team of experts from the Inland Fisheries Institute in Olsztyn is planning to create a gene bank - a unique safety belt for the survival of the Oder's ecosystems. The work is being performed by a team of hydrobiologists, ichthyologists and geneticists, with the participation of scientists from Poland and abroad.