Man-Made Noises Have Deadly Side Effects For Ocean Dwellers
Humans are not exactly quiet creatures. In fact, we can be downright noisy. But how does our man-made, or anthropogenic, noise affect the organisms around us?
A recent study conducted by Scientists from the Universities of Exeter and Bristol has found that "acute acoustic events" on the water, such as ships passing, actually does adversely affect marine life.
The marine creatures featured in the study were European eels, a species which breeds in the middle of the North Atlantic and then migrates to the European coast. The species is considered to be critically endangered, with the population of wild European eels having dropped 90% since the 1970s due to pollution and overfishing.
The study showed that when noises were involved, European eels were 50% less likely to respond appropriately to a predatory threat (i.e., flee the predator), and those that did respond had a 25% slower reaction time. Says study co-author Dr. Andy Radford, "The fact that eels were affected physiologically and spatially suggests that other important functions may also be affected. We focused on anti-predator responses as, unlike impacts on movement or feeding, there is no way to compensate for being eaten after the disturbance goes away." This essentially means that eels are less capable of avoiding predatory fish if there are acoustic disturbances, which could incur an even greater dip in the eel's already scant population.
Since this phenomenon likely affects whole populations, Dr. Simpson asserts that "the endangered eel, which has seen a 90% crash in abundance over the past 20 years due to climate change, may have one more problem to deal with as they cross busy coastal areas."
Reports from the United States National Oceanographic and Atmospheric Administration confirm that underwater noise has been doubling every 10 years. Though the military has been concerned with underwater noise since World War II, it has become clear that it's not just the military's problem.
More work will need to be done to ascertain the widespread effects of anthropogenic noise if regulations are to be put in place. Dr. Simpson says that "If we want to effectively manage noise in the marine environment, we next need to assess the spatial scale over which individual animals and populations are affected. This means taking experiments like this one to offshore environments near to real-world noise sources."
The International Maritime Organization currently has voluntary regulations in place, but as the regulations are not mandatory they cannot be legally enforced.