Düsseldorf The species composition of the Rhine is constantly changing. There are currently 43 species of fish living in the Lower Rhine. Here we introduce some animals and plants and explain their ecological functions.
The Rhine is not only a waterway and an important site for industry, but also a vital river with various habitats for plants and animals. However, over the past 200 years, the aquatic environment has undergone some changes that led, for example, to the extinction of sturgeon. Here we present some creatures from the Lower Rhine and explain their ecological functions.
According to the technical report “Development and ecological potential of Rhine river fish in NRW” by the State Agency for Nature, Environment and Consumer Protection (LANUV) in NRW, 43 species of fish and cyclostomes that were originally found in the Lower Rhine have been documented in historical records. After World War II, the Rhine was heavily polluted by domestic and industrial wastewater. In the period from 1880 to 1950, 30 species were documented. At the height of the pollution, researchers counted only 28 species. Especially thanks to the introduction of sewage treatment plants in the 1970s, the water quality has improved again.
From 1984 to 2017, LANUV managed to identify 43 species. The most common fish species in the Lower Rhine are the black-mouthed guppy, grimace, ede, cockroach, perch, ooze, and eel. The eel is considered an endangered species in the NRW. In 1986, in a chemical accident at the Sandox chemical plant, toxic extinguishing water flowed into the Rhine River, killing at least 150,000 people. Since 2010, there has been a program to reintroduce eels into the Rhine. Programs to reintroduce migratory salmon and salmon also exist, and initial successes can be seen.
Of the 43 proven species, 13 are invasive; They were introduced directly by humans, either directly or indirectly from foreign regions. Experts refer to these introduced species as Neozoan. Invasive gobies in particular seem to feel very comfortable on the Rhine. The highly competitive black-mouthed goby is currently the dominant species, and according to the technical report, this has so far given it an edge in competition for food. However, there has been no apparent decrease so far in stocks of local fish species.
Despite the wastewater treatment plants, the ingress of micro- and contaminants still poses a burden to the organisms in the water. Pharmaceuticals, X-ray contrast agents, beauty products, pesticides and other chemicals are increasingly entering water bodies from homes, commerce and industry — above all via household wastewater, as highlighted in the 2020 Environmental Status Report from the Ministry of Environment, Agriculture, Nature Conservation and Conservation. consumer. According to the International Commission for the Protection of the Rhine (ICPR), organic and inorganic chemical pollution still plays a role in fish health and reproductive capacity.
Water temperature also affects life on the Rhine. According to the ICPR, the temperature of the river’s water increases due to convection on the Rhine (such as the use of cooling water) and a general rise in temperature. As a result, the cold-loving native species have to retreat to cooler places such as tributaries and higher groundwater. Invasive species that are more sensitive to heat can spread.
The beach areas are also increasingly covered with silt. This means that there are no nursery areas for young fish. This changes the community of species. The Federal Environment Agency assumes that the number of small invertebrates could be reduced by up to 41 percent by 2099 as a result of the climate change-related increase in low-water events. In the case of fish, a local biodiversity loss of 4 to 22 percent is expected by 2070.
Here is the photo gallery: These animals live in the Lower Rhine