In August, tons of dead fish wash up on the banks of the Oder. Experts believe that excessive salinity is one of the reasons for the mass extinction. Since then, the flow has been carefully controlled. However, the current measurement gives reason for concern again.
Increased salinity has been found in the German-Polish border river Oder. According to the data from a measuring station from the Brandenburg State Office for the Environment in Frankfurt (Oder), the salt content is about as high as when the fish died last summer. Experts saw the reasons for the environmental catastrophe in August as being discharged salt combined with low water and high temperatures, which led to a massive proliferation of a toxic species of algae (Prymnesium parvum).
Why the increased load came again remains unclear at first. The observed conductivities of the Oder water are below the peak values measured in summer, but significantly above the average values of the past few years. And: "We now have twice as much water in the Oder," said water ecologist Christian Wolter from the Leibniz Institute for Freshwater Ecology and Inland Fisheries "Zeit online". "That means the amount of salt is at least as high or even higher than in summer."
The electrical conductivity in the water is an indicator of the salt content. Despite the high measured values, there is currently no acute danger. According to the Ministry of the Environment in Potsdam, no mass proliferation of the algae is to be expected given the current lower water temperatures of 13 degrees. And expert Wolter also confirmed to the newspaper: "The water temperatures are now too low for an algae bloom."
The values in the river would continue to be monitored, according to the Ministry of the Environment. The Middle Oder, which forms the border between Ratzdorf and Kietz (Oder-Spree district), has been carrying high salt loads for years. The "cohabitation" occurring in the Oder has obviously adapted both to the high basic load and to the fluctuations and peaks that have been recorded.
Dealing with the fish kills strained German relations with the neighboring country. There was no coordinated German-Polish analysis. Federal Environment Minister Steffi Lemke emphasized the role of "human activities" that led to this "serious environmental catastrophe". Salt discharges were primarily responsible for the massive and unusual growth of the toxic algae. The Polish experts, on the other hand, did not speak explicitly of "salt discharges" and instead emphasized that the river had been polluted for a long time and that the low water level had led to a higher salt concentration. The all-important question of who exactly was responsible for these unusually high amounts of salt in the Oder remains unresolved on both sides to this day.
