The oceans have their own one of a kind soundscape. Many marine organisms, for example, use sound for echolocation, navigation or conversation with their fellow creatures. In recent decades, however, more and more sounds caused by human activities are permeating the waters. A study from the Alfred Wegener Institute now presents evidence that these sounds affect certain invertebrates that live in and on the seabed in such a way that the important functions they perform for their ecosystems may be impacted.
Invertebrates such as crustaceans, mussels and worms are ecosystem engineers. They continually modify the sediments in which they live by digging, feeding, aerating and fertilizing with their excrement. These activities are essential to nutrient cycling in the ocean, allowing more carbon to be stored from dead organic matter on the seabed and recycling of nutrients.
Rising temperatures, ocean acidification and pollutants are placing organisms in marine ecosystems under increasing stress. In recent decades, noise caused by human activities has also increasingly contributed to the problem, affecting the behavior, foraging or conversation of marine animals. The sounds of blasting and resource extraction roar across the oceans along with the loud hum of freighters and pleasure boats. A research team from the Alfred Wegener Institute, Helmholtz Center for Polar and Maritime Research (AWI) in Bremerhaven has just shown in a study published in the journal Environmental Air pollution that these sounds stress not only marine mammals, but also invertebrates. “We studied how seafloor crustaceans, mussels, and worms respond to low-frequency noise and how often and how intensely they are able to transform and break down sediment during noise exposure,” says Sheng. V. Wang of the AWI Department of Biosciences. Low frequency noise is sound whose frequencies are between 10 and 500 hertz and in water these sounds can be transmitted over several kilometres.
Despite the steady increase in air pollution caused by human activities, little is known about how noise affects seafloor invertebrates . To help fill this research gap, AWI scientists studied in the lab how Baltic amphipods, earthworms and clams are affected by sound waves with frequencies between 100 and 200 hertz using so-called “noise eggs”. “After six days, we could clearly see that all three species reacted to noise, even though they belong to very different groups of animals that do not have hearing organs,” says ecologist Dr Jan Beermann. ‘AWI. For example, amphipods buried themselves much less and less deeply in the sediments. No clear response was seen for the arenas, but they seemed to behave more inconsistently. Potential strain responses have been noted for Baltic clams that need to be further investigated. The researchers emphasize, however, the urgent need for field research, as experimental setups in laboratory conditions do not encompass the full complexity of mother nature.
This additional noise Anthropogenic could prevent seabed invertebrates from cultivating and restructuring sediments, potentially affecting important functions of marine ecosystems, from nutrient supply to food availability for those higher up in the ocean. food web, such as fish. “Things could get even ‘noisier’ on the seabed due to human activities,” says Beermann. “We are just beginning to understand exactly how noise processes work here. However, understanding this is crucial for the long lasting use of our oceans,” which is why the team plans to continue research in this area. Experiments at other AWI internet sites such as Heligoland and Sylt are also to provide more detailed results as part of a project in collaboration with European partner research institutes. The international platform JPI Oceans finances the project.