Offshore Oil & Gas Seismic Airguns Kill Vastly More Zooplankton Than Previously Thought

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The use of seismic airguns in offshore oil and gas exploration work is killing vastly more zooplankton than was previously known, according to a new study published in the journal Nature Ecology and Evolution.

The research relied on real-world measurements of zooplankton numbers (using both sonar and nets) both before and after seismic airgun blasts were made off of southern Tasmania. It found that numbers dropped by 64% within one hour of a blast, and that 2 to 3 times as many zooplankton were found dead after a blast as compared to before one.

What’s particularly interesting is that researchers had previously estimated that impacts on zooplankton would only be felt within 33 feet of a seismic blast … something that is completely inaccurate, apparently. The new work shows that impacts occur as far away as 0.7 miles.

This is something that’s very important to take note of because of how utterly dependent most large marine animal life is on zooplankton for its survival, one way or another. While oil and gas exploration efforts using seismic airguns of course don’t cover the whole of the ocean, and certainly don’t impact all of it at once … the findings are just one amongst nearly countless ways that humans are wrecking the oceans and undermining the basis on which most marine food webs exist.

Some reading this may scoff at it, or say that it’s not that important because of other growing problems, but the reality is that this is a big deal. With the seemingly inevitable collapse of most commercial fisheries over the coming decades taken into account, as well as the productivity and yield issues facing the agricultural systems of the world, people are going to be dealing with serious food constraint issues before too long. Amplifying those in any way causes further strain on a fragile human society.

While it’s true that there’s a vast amount of food that’s produced every year that never ends up being eaten by people — but instead ends up as “waste” — not much of that waste actually relates to the staple foods that people generally rely upon calorically. While potential improvements to the food system could possibly help, most of the issues relating to “waste” are built into the current system — so long as people “need” to eat foods that are out of season, that can’t be grown in the region in which they live, that can’t have any blemishes of any kind (and are supposed to look like plastic), and must be “cheap,” then waste will remain a part of the system. This is owing to realities inherent with the expensive, long-distance shipment of food items, and also with storage (sometimes it’s cheaper to not even bother harvesting a crop because prices are too low for it to be economical to do so, etc.).

So, to say that again, there are serious food supply problems looming as a result of diminishing agricultural productivity — regardless of there being a lot of food that is “wasted” every year in developed countries — and the ongoing collapse of commercial fisheries in many parts of the world is going to greatly exacerbate this. Amongst the many ways that people are making it hard for zooplankton to survive in their current numbers, the use of seismic airguns during oil and gas exploration probably isn’t anywhere near the worst, but it’s still worth noting.

Getting back to the new research, The Verge provides more info: “Oil and gas companies looking for offshore natural resources use seismic airguns to blast compressed air through the water and into the seafloor. The noise produced by these airguns is louder than a Saturn V rocket during launch, according to Nature. So researchers wanted to see what the effects are on the sea’s base of the food chain, the zooplankton.”

“… It’s not 100% clear how the airguns are causing the die-offs, but it’s possible the blast throws off the receptors the animals use to navigate, disorienting them and causing them to die, according to Nature. Because zooplankton is key for feeding larger marine animals, the die-offs could have serious cascading effects.”

“Plankton underpin whole ocean productivity,” commented lead author Robert McCauley, an associate professor at Curtin University in Australia. “Their presence impacts right across the health of the ecosystem so it’s important we pay attention to their future.”

On a related note, earlier research has found that the use of seismic airguns during oil and gas exploration seems to be causing a lot of problems for marine mammals that rely upon vocalizations (and excellent hearing) for a variety of critical tasks, such as navigation, social behavior, and general health and wellbeing — that is to say, marine mammals such as whales and dolphins.

Image by uwe kils (some rights reserved)

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James Ayre

James Ayre's background is predominantly in geopolitics and history, but he has an obsessive interest in pretty much everything. After an early life spent in the Imperial Free City of Dortmund, James followed the river Ruhr to Cofbuokheim, where he attended the University of Astnide. And where he also briefly considered entering the coal mining business. He currently writes for a living, on a broad variety of subjects, ranging from science, to politics, to military history, to renewable energy.

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