Sources: The University of Adelaide, Science Daily
Nutrient polution emptying into seas, coming from human activity, such as agriculture and industries is changing the sounds made by the creatures living in the sea.
What’s the big idea?
Marine life is almost solely relying on other senses in order to find their way into the dark depths of the sea. Are fish blind? No, or most of them not at least, but their eyes can only view a minimum of a few meters at best and the rest looks really dark and fading, plus if for an animal it is really hard to navigate through the woods, imagine how hard it can be for fish (as their smell is also limited, and most of the living creatures of the sea do not have a breathing system, such as the mammals, making them lack the sense of smell). How do they navigate into the sea? By using sounds! Actually, the sonar was invented by studying them, but this is another story.
What happens when huge portions of trash coming from human activity end up into the sea? They create big masses. The sound echo made by any marine organism falls on these masses and returns back to the animal, meaning that there is an obstacle ahead. The animal will be confused and probably lose its way, like you would be confused if a whole new street was not mentioned on the version of the Google Map application you were using. As for what happens in this particular case, here is the full story:
According to the journal, Landscape Ecology, the ecosystems degraded by “eutrophication”, as a result of the run-offs coming from cities and industries, or agricultural land, are more silent than other marine ecosystems. The magnitude of the sound was the same as the sound made at degrading ecosystems, or those soon-to-undergo climate changes. Study leader Associate Professor Ivan Nagelkerken mentioned that habitats, such as the kelp forests, or the seagrass beds are too important for the biodiversity marine life and also work as nursery habitats for countless species. However the decrease of sound, is almost the same that can be found at any ecosystem that has been affected by global ocean acidification. Of course, that sound is immensely important to some species that find shelter in these habitats, but the demise of biological sounds will probably have a negative effect on the local marine life and the replenishment of fish populations.