The biologist’s comment

— What are the consequences of the Oder’s contamination for the entire ecosystem?

Dr Robert Maślak, a biologist, Department of Evolutionary Biology and Vertebrates Conservation:
— Enormous. We’re likely dealing with the biggest ecological disaster in the history of the Oder River. Unfortunately, we still don’ know the cause or source of this pollution. The media are spreading assumptions but those are still merely theories. The key to assessing the consequences is the substance that has poisoned the river. As of now, we’re talking about several thousand caught dead fish, which means that the actual number reaches millions. Most of them, deep in the water, are unnoticeable for us. We have also received information about dead seagulls, herons, and beavers.

— What if the reports about mercury contamination in Germany are confirmed?

— That would be bad news. Mercury gathers in organisms and gradually damages the nervous systems and other organs. The entire ecosystem freezes for a long time. Some rivers in Asia have been dead for decades because of mercury contamination. This is a grave danger for the ecosystem and for humans. In the fifties, two thousand people have died because of a mercury drop and ten thousand were seriously ill.

— Can the current damage be minimised right now?

— Our options are limited. Apart from removing the water from storage reservoirs to dilute the poison, there isn’t much we can do. Such actions should be taken in the first days of the disaster. The early time of detecting the source of pollution is crucial for preventing the negative effects and stopping the leak. Because of the scale of the contamination, it is believed that the poison could have been leaking into the Oder for a few days.

— What can be done to prevent any future disasters like this?

— We should introduce exact procedures, shorten decision paths, finance and equip inspectorates for environmental protection in appropriate capabilities, and stop tolerating illegal minor drops that keep happening with a silent encouragement of governments responsible for the state of the environment. We need a constant supervising of the Oder, and not just as an intervention measure.

The ichthyologist’s comment

— Do we know how many species and what number of fish have suffered because of the contamination?

Dr hab. Jan Kotusz, prof. UWr, a biologist and ichthyologist, Museum of Natural History:
— Across the contaminated section there is usually about 25 species. Some of them, for example crucians, are more immune to oxygen deficit than others, but there are no species immune to the poison we are dealing with now. Possibly all local species have suffered. We cannot give the precise number since we have no exact data about the numbers of specific species. Still, we’re surely talking about tens of thousands of adult fish and hundreds of thousands of parr.

— Is there any chance that even the smallest number of fish have survived?

— We can only guess. There might be some places the poison had not reached because of the currents and in those places some fish might have survived. Indeed, those will be pioneer individuals that will breed decimated populations.

—What are the long-term consequences of the poisoning of fish?

— Local populations have been wiped out. Both the oldest and the youngest classes are gone, even the ones born this year. Such losses in the Oder will take years to recover. We must remember that the invertebrates, which are the nutrition for fish, have died, too. So first, the fish habitats and their food sources must regenerate. Then, those twenty-something species will have to re-colonize the area and build stable, self-reliant populations, and learn to interact with each other.

— What are the chances there will be fish again in the river?

— The most crucial are the natural processes I have already mentioned, because they concern the entire fish community of the Oder. Once the destroyed habitats recover, we must also hope for immigration of fish from unpolluted areas. We can support this process through artificial fish stocking, just like the ones conducted by fishermen unions. However, this only concerns a few species that the fishermen typically catch, with already developed artificial stocking techniques in fish habitats.

— How does the contamination affect the entire ecosystem?

— The contamination was noticed through the observation of the lifeless fish. Essentially, humans have a poor perception of what happens in aquatic ecosystems, since we cannot reach them as easily as the terrestrial ones. Unfortunately, the lifeless fish are a sign of rapid ecosystem changes. The pollution affects all life forms including plants, invertebrates, fish and semiterrestrial animals like amphibians, aquatic and wading birds, and numerous mammals. These days, when there is drought, wild land animals often drink water from the river because there aren’t many stable waters beside rivers. The Oder is the bloodstream of the remaining natural world in our region and its most important biodiversity centre. The contamination of this river is especially harmful for our environment.

— Can anything be done to prevent the poisoning of any more fish?

— The damage is done and there’s not much that we can do right now. We can only catch the dead fish so that their decomposing bodies don’t become a source of another pollution.

— In your opinion, what should be done to prevent any future disasters like this?

— We can effectively counteract such situation in the future, and the solutions are obvious. Of course, it’s the general and local administrations’ duty to exercise the law and not to allow contamination to happen. However, the improvement of the Oder’s auto-purification is even more important. The river can do that on a large scale, but it must be at least partially natural. We could move the bed’s embankments where it’s possible and let the river create meanders, oxbow lakes, and wetlands. Those ecosystems are excellent at capturing pollutions and including them in the circulation. However, such as action, called river restoration, have its price. Currently, the contaminated section of the Oder is strictly regulated. It flows in a deepened riverbed, and its meanders were cut off to improve the inland waterways. As a result, the Oder’s auto-purification ability is limited. The inland waterways can, of course, function in a natural or semi-natural river, but they must not be prioritized. Auto-purification of a river full of canals and enormous transporting barges is nearly impossible.

The chemist’s comment

— Do we know what kind of substances can lead to contamination on such a scale?

Dr Maciej Modzel, a chemist, Department of Organic Chemistry:
— The list of water-poisoning substances is long. It could be various toxins, detergents, heavy metals, but also oxidising or corrosive substances. It’s hard to specify what substances could cause that effect on the fish in the Oder.

— One of the main suspects is mesitylene. Is that a good lead? What kind of substance is that?

 — Mesitylene is an aromatic hydrocarbon, a derivate of benzene. It’s used as a solvent in laboratories and industries. It can also by used to increase the octane number of petrol.
Is it a good lead? It might be “one of the main suspects” but although it was detected in the July 28^th samples, as far as I know, it was absent in the subsequent ones. This suggests that it did not poison the fish.
If the reports of the water’s hyperoxygenation are true, we could suspect a substance that releases oxygen as a result of chemical reactions. Such chemical compounds are often harmful for aquatic organisms. It could also turn out, however, that the two substances acted simultaneously, or that there’s a third one that we don’t know about yet. Further tests are necessary for both identifying the toxic substances in the river (that’s a task for the scientists) and determining the reasons how they got there (this is mainly a task for the prosecutor).
It’s also worth remembering that “the does makes the poison” (Paracelsus). The water levels in many rivers are quite low because of droughts. This means that the same amount of a toxic substance will have a higher concentration in a river with less water. It directly affects the biological consequences.

— According to the media, the German laboratories have confirmed a high level of mercury in the Oder. How does mercury affect living organisms?

— Mercury is a heavy metal, harmful to living organisms. It damages the kidneys, the nervous system, and mucosae, so that also includes the digestive system. As of now, we don’t know (or at least I have no such information) what was the form of the mercury in the Ode – whether it was a metal mercury (sparingly soluble in water) or its compounds. Of the latter, the most dangerous are organometallic compounds, such as dimethylmercury.
Unfortunately, mercury and its compounds have a tendency for a bioaccumulation. The most known example is the Minamata disease. In the fifties, a factory in Japan released wastewater with tiny amounts of mercury into the Minamata bay. The substance was absorbed by organisms in the river and gathered inside them, travelling up the food chain. The concentration of mercury in the predators and shellfish living in the bay was a few thousand times higher than that in the water. Since those animals were the main source of food for the locals, many people were poisoned and over 1700 died.
There’s no reason to panic, especially that we don’t know exactly how much mercury there actually is in the Oder, how long it has been there and in what form. However, until the matter is settled, we shouldn’t consume any fish from the river nor drink untreated water (including giving it to animals). If the information about mercury turns out to be true, consuming the Oder fish will have to be forbidden for a long time.

— Can we minimise the damage caused by the contamination?

— I don’t know if we’re able to truly protect the organisms living in the lower reaches of the river. Nor am I familiar with any effective ways of removing the mesitylene from the river, but this question should be asked to someone who’s a professional in wastewater treatment. However, my intuition tells me that the size of the river and the time scale make protecting the animals impossible.
As for minimising the damage for us, I think the most sensible thing to do is refrain from baths, water sports and drinking untreated water until the situation is clear.

— What should be done to prevent any future disasters like this?

— First of all, we need to find the cause. That will allow to introduce any meaningful recovery plans. An improved supervision or tightening of the rules of releasing wastewater might also be necessary. A separate issue is increasing the water levels, which equals fighting the drought and general climate changes, but again – this is not my area of competence.

The geographer’s comment

— Can we tell where the contamination started?

Dr Łukasz Stachnik, a geographer, Institute of Geography and Regional Development:
— Unfortunately, based on the information received from the Provincial Environmental Inspectorates in Wrocław, Opole, Zielona Góra and Szczecin, as well as from fishermen unions, we can’t explicitly tell the source of the contamination. On such an early stage there isn’t much publicly available data which would facilitate that. What we do know is that the contamination caused by the derivatives of aromatic and cyclic hydrocarbons (including mesitylene, a toxic organic solvent) was measured with an 80% probability on July 28^th in three locations north from Wrocław (Jaz Lipki, Łany and Oława). Morover, Germany have confirmed the high concentration of mercury in middle river. Because of the wide range of lifeless fish, it can be said that the contamination originates in the Lower Silesia. Other suspected source location is Kanał Gliwicki (the Gliwice Channel) near Kędzierzyn-Koźle.

— Can we predict which part of the Oder is poisoned?

— According to the information provided by the Provincial Environmental Inspectorates in Wrocław on August 5^th, the concentration of mesitylene has decreased in places where it was earlier noted as high and is no longer dangerous. Similarly, there was no mesitylene detected in the lower reaches of the Oder (West-Pomeranian and Lubuskie Voivodeships). However, the outcomes of the contamination are still being observed, like mass deaths of fish, some mammals (i.e. beavers), and aquatic birds. A mass of lifeless fish travels down the Oder and has recently reached Kostrzyń, and its decomposition can have negative consequences for the freshwater environment. This process can be intensified by high oxygen levels noted while the fish were dying.

— Is there anything that can be done to minimise the damage?

— It’s difficult to say. We don’t know the substance that caused it, the source of the contamination, and how it relocates down the river. Beside the possible mesitylene contamination, the Ministry of Environment of the State of Brandenburg (MLEUV) has noted high mercury concentrations in the middle Oder. Right now, the key is to find the type and the source of the pollution and take effective measures to fight it. It’s also necessary to remove dead animals from the water.

— How does the contamination affect the entire ecosystem?

— The consequences for the environment are significant, because apart from mass fish deaths, other parts of the aquatic ecosystem are endangered. The absence of fish might disturb the ecological balance and worsen the water quality. Additionally, the pollution might amass in the higher parts of the food chain if predatory fish and birds of prey scavenge the poisoned fish.
The environmental pollution also influences the animals living in coastal ecosystem, such as beavers. However, even more important is the contamination of the river’s bottom sediments, especially in the case of substances heavier than water (like mercury and mesitylene). On the other hand, the accumulation of contamination in the bottom sediments can cause their gradual release into the flowing waters. It also increases the risk of polluting the groundwaters.

— What can be done to prevent any future situations like this?

— This disaster points at the poor communication between institutions responsible for the surveillance and protection of the water environment. Despite the information about lifeless fish, any precautionary action was taken over a dozen days too late. In the future, it’s crucial to constantly monitor the water quality and improve the coordination between institutions in charge of the water environment. A good example of quick action are the Germans, who detected the mercury contamination in one day.