An Invisible Threat to an Invisible Victim: How Sound is Affecting Zooplankton.
Let’s take a moment, to be honest with ourselves. We as a species are pretty biased. Emotions, prejudices…you name it! In fact, a study showed that, proportionate to the number of known species in a taxon, a majority of invertebrate taxons were understudied in comparison to vertebrate groups. It follows that we might be even more ignorant about a group of organisms we can’t even see, the zooplankton.
Often lost in the “noise” of other climate change topics, noise pollution is a serious threat to many animals around the globe. You may or may not know this but noise pollution affects aquatic habitats as well as terrestrial ones. One major contributor is seismic air guns used to survey the seabed for fossil fuel. They achieve this by blasting air, producing about 220–250 decibels per pulse. To put this into context, these pulses of air are louder than a Saturn V rocket during launch.
It has been documented that many marine species that use sound as a means of communication avoid sites of high noise levels, while other research suggests very real consequences of noise pollution towards the hearing organs of fishes. But what of the zooplankton, how do they fit into all of this?
In the past, it has been assumed that planktons were safe from the effects of noise pollution as they were too small to reflect sound waves, but recent studies have suggested otherwise.
For example, a team of researchers conducted a survey, before and after a seismic survey, on the population of zooplankton off the southeast coast of Tasmania. They found a 64% drop in zooplankton numbers just one hour after the seismic survey.
While there is no clear evidence that the seismic guns are directly responsible for the death of zooplankton it is nonetheless clear that it has some negative impacts on the fitness of the zooplankton. One researcher from the same study suggests that these sound waves might be damaging sensory hair-like structures that aid in predator avoidance and movement.
Unsurprisingly Trump is not Helping
As of the Trump administration, the president of the United States plans on allowing, for the first time, seismic surveys off the Atlantic coasts. Many areas protected under Barack Obama’s climate and environmental policies will be under threat if undone. As of 27 June 2017, 6 oil companies are currently awaiting permits, which may or may not be approved.
The role zooplankton play in the ecosystem is invaluable, lying so close to the base of the food web their loss will definitely be felt. Furthermore, zooplankton also includes the larval stages of much marine life, their deaths would mean the loss of successive generations of larger fauna. Although small and hard to see, we must always remember to keep them in mind.