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The spill of toxic products on the Besòs river

The spill of toxic products on the Besòs river

Last Wednesday, December 11, a toxic product spilled into the Besòs river during an industry fire in Montornès del Vallès that caused a notorious fish death. While the fish have been made visible to the impact, the spill has affected the rest of the organisms in the ecosystem (algae, macrophytes and invertebrates) and the toxic compounds may be accumulating in the food web. Much has been speculated in the media about the decline in the river's conservation status and compared to the deplorable state it was in in the 1980's, when it was declared one of the most polluted rivers in the world. 'Europe. The extent of the impact, however, can only be evaluated through scientific studies.

Impact assessment on the fish community

There are seven species in the fish community of the Besòs river, four of which are native (eel, mountain barb, catfish and llobarrera) and three allochthons (carp, shrimp and wolf) of river). One of them, the eel, is a species listed by the IUCN (International Union for Conservation of Nature) in the category "CR" (critically endangered). Due to the spill in Montornès del Vallès, the ACA (Catalan Water Agency, Government of Catalonia) has declared the environmental emergency on the Besòs river and has commissioned the research team in biology, ecology and behavior in freshwater fish from the UB, led by Dra. Dolors Vinyoles (Associate Professor at the Faculty of Biology), a study to determine the extent of the impact. The research team is aware of this ecosystem as it has been conducting regular fish surveys by various public administrations since 2006. The study, which starts this week, will also be involved experts from other institutions (from IDAEA-CSCIC and UAB).

Expectations for the recovery of the river

During the years of study at the Besòs, the UB's research team could not confirm the reproduction of native fish species in the lower reaches of the river. With the exception of eel and llobarrera, which are migratory species that breed in the sea, young individuals born during the year are not usually found in the lower reaches of the river. Mountain barbel and catfish populations tend to be unstructured and constitute individuals of a narrow range of sizes. This may be due to breeding in higher stretches of the basin (generally in a better state of conservation) and to downstream fish recolonization occurring periodically due to the effects of rainfall and dragging individuals. Urban rivers, such as Besòs, are usually fed by purified water rich in nutrients (nitrogen and phosphate compounds) and emerging compounds (pharmaceuticals, among others). All of these compounds eventually produce chronic conditions that shorten the life of fish and impede their reproduction. Urban rivers, therefore, are very vulnerable ecosystems. That is why it is very difficult to predict how long the ecosystem will take to recover, but the environmental conditions of the river have improved substantially compared to those presented by the river 30 years ago, which allows us to have moderately optimistic expectations. with respect to the period of recovery of the section affected to a state similar to before this impact. Wastewater treatment plants (WWTPs) will continue to function, public administrations will continue to work to recover and improve the ecosystem, and citizens will continue to look after this river, which largely runs through an urban and industrial landscape that needs take special care of it.


Dolors Vinyoles

Associate Professor. Department of Evolutionary Biology, Ecology and Environmental Sciences (BEECA). Faculty of Biology.