Echoes in Queen Charlotte Sound: sustainability and the price of progress?
We have a yacht that we keep at Waikawa Marina in Queen Charlotte Sound. And what a fabulous place it is, especially if, like me, you love wildlife. But it faces many threats.
Sounds like Paradise?
Queen Charlotte Sound certainly seems to be a marine mammal’s paradise. Four species of dolphin are found here – bottlenose, Hectors, dusky and common. Orca, southern right whales, humpback whales, as well as deeper water species such as pilot whales, all visit these waters too. And, of course, we mustn’t forget the wonderful New Zealand fur seals.
“Follow my Leader” • Noelle Bennett • a pod of Bottlenose dolphins leading our boat up Queen Charlotte Sound
It’s not all about marine mammals, although, to be fair, they tend to be the main headline grabbers and the animals so many people seem to come here to see. The bird life is pretty special too. Little blue penguins scurry around the waters, probably not even being noticed by most people. Their classic habit of sticking their heads under the water when you go past, presumably in the misguided hope that you don’t see them, is just so funny to see. Then there are the gannets with those insane dives and the shearwaters fluttering delicately just above the water surface and gliding effortlessly on outstretched wings, never once mistiming those glides, never hitting the waves. Oh, and we mustn’t forget the shags – there are four species of those – so often seen flying in formation, always looking as though they’re on a mission.
I suspect many of you know that two of the four species of dolphins I mentioned are either nationally endangered or nationally vulnerable. But I wonder how many of you knew that one of the shag species, the King shag, is found only in the Marlborough Sounds. Yes, that’s right, it’s found nowhere else in the world except the Marlborough Sounds. This makes them extremely vulnerable to simply being snuffed out if something goes wrong.
“Hey, What’s That?” • Noelle Bennett • King shags in Queen Charlotte Sound
People pressure
Now Queen Charlotte Sound is, of course, scenically extremely beautiful and the weather is (mostly!) good. That makes it something of a hotspot for boaties. And therein could lie a potential conflict – but probably not the one that immediately springs to your mind.
You’ll need some background, so I’ll keep you guessing just a few moments longer! There are two marinas in Queen Charlotte Sound – Picton Marina with 254 berths and Waikawa Marina with 600 berths. They are about 4kms apart by road (possibly double that if you choose to travel between the two by sea). All berths in both these marinas are, generally speaking, full and many boat owners end up being put on a waiting list to lease a berth. So if demand is clearly outstripping supply, what do you do to solve that issue? Well obviously, you put more berths in! And that was the decision that was made, final resource consent being granted within the last three or four years for an extension to Waikawa Marina. This would add another 250 or so berths, making it the country’s second largest marina behind Auckland. So that simply has to be good for the local economy, right?
“What price change” • Noelle Bennett • Waikawa Marina, Queen Charlotte Sound
Until work on this extension began, I had never consciously thought about how marinas come into being and have never seen one under construction. For this extension anyway, it started with the construction of the road. Every day, huge trucks rumbled down the existing marina to empty their loads of rocks and ‘in-fill’ into the sea. All this was duly worked into place until the road was functional and the sea was kept at bay by the new rock wall.
Then it was time to start building the breakwater and installing the jetties. Enter the beast called a ‘pile driver’. It’s a strange contraption that bangs huge metal pipes (piles) into the seabed. Impact pile-driving uses a hammer or drop weight which produces an impulsive, repetitive thud each time it forces the pile downward.
It gets worse! As we walked back to our berth, the single thud we’d heard when we were close to the pile driver was replaced with a double thud each time the piles were driven deeper. Curiously, the two thuds sounded quite different from each other – the first was dull whilst the second had more of a ringing sound.
“I wonder why we hear the thud twice and they both sound different?” I asked my other half.
“Because sound travels through water quicker than through the air. We’re hearing both because we’re closer to the water surface here’’ spoke The Oracle, with a degree of confidence that made me realise he wasn’t winding me up!
Physics 101: you know you should have paid more attention at school!
That set me thinking. If my significant other’s hypothesis was correct and this was what we were hearing above water, what on earth did it sound like underwater? It turns out, this sound is among the loudest underwater sounds, particularly when steel piles are being driven. Sound is actually a pressure wave, but the wave behaves slightly differently when it travels through air compared to when it travels through water. Water is denser than air, so it takes more energy to generate a sound wave in water, but once a wave has started, it will travel faster than it would do in air. Most of us remain blissfully unaware of the long-distance transmission of underwater sounds because we mainly hear sound waves transmitted through air.
It works a bit like a relay race, but in this case the runners are particles and the baton they are passing along is the energy of vibration. In a sound wave, a particle picks up some energy and keeps it until it bumps into a neighbouring particle. The next particle will then pick up the energy and transfer it to the next one in the chain and so on. This happens extremely quickly and is detected as a wave of pressure. The particles are generally further apart in air than in water, so the vibrating particle has to travel further in air before it bumps into another particle and passes its energy parcel onward. Once the sound wave starts to move in water, it can quickly transmit vibration energy from one particle to the next so sound travels over four times faster in water than in air. Water temperature and pressure also affect underwater sound transmission – these gradients sometimes funnel the sound wave into a sort of ‘sound channel’ which allows it to travel thousands of kilometres without really losing any energy.
Sound Pollution and Marine Ecosystems
So what impact might this noise have on those marine mammals I mentioned earlier? A Lyttleton study (Leunissen & Dawson 2018) suggested that marine mammals could potentially suffer hearing stress and injury as well as ‘habitat avoidance’ (where they go somewhere else quieter that may not otherwise be as suitable for them). That study also noted that Hectors dolphins may be particularly sensitive to piling-generated noise. But, having said that, there have been no studies looking at the long-term effects of exposure to pile-driving noise on marine mammals. Short-term avoidance reactions might not necessarily lead to long-term effects or more lasting population impacts such as disruptions to reproduction or even survival.
Don’t think for a moment that I’m saying the marina shouldn’t be here or that it shouldn’t be extended. After all, as I said right at the outset, our boat is here. But I wonder how many of the rest of you are just like me and have never really considered what is involved in the creation of these playgrounds for the human race. What concerns me is that we tend to see nature as something that is there as a commodity – something simply to be used as and when we please and in whatever way we choose without so much as a second thought for other living creatures that may call it home. But isn’t that attitude somewhat flawed? What seems to be clear is that noise pollution can have various negative effects on marine mammals. And who knows what effects it may have on birds such as the King shags.
The pile-driving here was predicted to last for between four and six months. We have now just about reached the twelve-month point from when the pile-driving started and it is still continuing (and yes, I do accept that there was a lockdown in August which would have impacted on the time-frames, but to that degree?).
People and nature: a last word from Einstein
Should it follow, therefore, that it is important to establish safe limits for man-made noise in ocean environments? After all, there are currently no national or standard guidelines for pile-driving activities within New Zealand waters. I guess it’s challenging to define a ‘safe’ limit when it is difficult to know to what extent a reaction to noise – whether behavioural or physiological – represents a significant problem for animals in the wild.
But then absence of evidence of impact is not the same as evidence of absence of impact! An ‘Environmental Precautionary Principle’ suggests that we should err on the side of caution even when we don’t know for certain whether the threat is serious. So should we err on the side of caution?
I really don’t know what the answer is, so in light of that fact I think I’ll leave the final summing up of these ramblings to Einstein who once said,
‘A human being…experiences himself, his thoughts and feelings as something separated from the rest, a kind of optical delusion of consciousness. This delusion is a kind of prison for us, restricting us to our personal desires and to affection for a few persons nearest to us. Our task must be to free ourselves from this prison by widening our circle of compassion to embrace all living creatures and the whole of nature in its beauty.’
“Progress?” • Noelle Bennett • The new piles might look innocent … but what damage might they have done to the Queen Charlotte Sound ecosystem?
About the author…
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This blog was written by Noelle Bennett, a photographer and writer in the Ecosystems Photography team. You can see more of Noelle’s photographs at http://www.noellebennettphotography.com/ and on Excio, New Zealand’s online photographic community at http://www.excio.io/
Reference cited: Leunissen EM, Dawson SM. Underwater noise levels of pile-driving in a New Zealand harbour, and the potential impacts on endangered Hector's dolphins. Mar Pollut Bull. 2018 Oct;135:195-204. doi: 10.1016/j.marpolbul.2018.07.024. Epub 2018 Jul 14. PMID: 30301031.
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