The world is in need of some mussel building. The humble mussel is not only a delicious seafood dish, it also is one of the most important species in the sea (and various salt-free bodies of water). Mussels act as a natural filtration system by pulling excessive nutrients from the water, which might otherwise have contributed to algal blooms and “dead zones.” Researchers from the University of Porto in Portugal and the Technical University of Munich have compiled the first comprehensive database of mussel populations in Europe’s freshwater, which they hope will be used to protect these essential mollusks.
Mussels comprise approximately 90 percent of the biomass on the bottom of a body of water. Used by the mussels to acquire food, their filtration abilities promote broad ecosystem health. Clean water encourages the growth of other invertebrates, which then enables larger populations of larger animals. “Because a single mussel filters up to 40 liters of water per day, we humans also benefit from the ecosystem services provided by mussels,” says Professor Jürgen Geist, Chair of Aquatic Systems Biology at the Technical University of Munich.
The team’s research has yielded guiding information about the diversity and resilience of Europe’s mussel population. “One result of the Europe-wide study is the extent of the gap between north and south,” says Geist. “There are fewer species in the north of Europe, for example Scandinavia, but the populations there are bigger.” The distribution of mussel species throughout Europe has been influenced by the rising and falling Ice Ages in Europe’s not-so-distant past, geographic barriers like the Alps, and fish which have served as hosts in allowing mussels to spread to new habitats. The research indicates hardier mussel species are better equipped to adapt to new environments and reestablish populations after a disruptive event.
The researchers note the greatest threats to mussel populations are pollution, man-made barriers like dams, invasive species, and climate change. They also point to a deep symbiotic relationship between mussels and local fish. “Because a mussel is highly dependent on its fish host and these are in decline, particular attention should be paid to the fish stocks,” says Professor Geist, “even if some of these fish species do not have any particular economic value.” To protect vulnerable mussels, the researchers suggest implementing conservation models specific to the type of mussel and its native ecosystem.