Are artificial reefs good for our oceans?
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Hello, I'm Hannah Gelbart and this is What In The World from the BBC World Service. We know that our oceans and the creatures living in them are under threat from things like warming waters and pollution. Now a huge cruise ship is about to be sunk on purpose to become the world's largest artificial reef. The people behind it say that it'll improve biodiversity, local tourism and fishing. But are artificial reefs actually good for the environment or even necessary?

Here with me in the studio to break this down is Georgina Ranard, our climate and science reporter. Hello, welcome back to the podcast. Thank you, Hannah. Good to be here. So let's start off with this ship. The Great Liner is 990 feet from stem to stern and she weighs in at 52,000 tons. The United States will carry 2,000 passengers. America claims she's the finest and fastest ship afloat.

It's called the SS United States and it's absolutely massive. It's longer than the Titanic and it is now about to go down to the bottom of the ocean off the coast of Florida. The SS United States, paint faded and a little rusty, left its home of 29 years in South Philadelphia. A judge ordered the ship be evicted from Pier 82. With limited options, officials from Okaloosa County, Florida came forward and purchased the SSUS for $1 million.

Its fate now anchored in a project to make the mighty liner the largest artificial reef in the world. So why is it being sunk? So if you think about this ship, like you said, it's huge. And it's one of those really glitzy, glamorous ocean liners from the 1950s. The main reason they're doing it, well, there's two reasons. One is because they want to create this artificial reef.

where the idea is that when they sink it, it creates this structure that fish, octopus, vertebrate plants can all colonise. So one is to improve that marine environment for those species, but the other is really also about tourism. The ship will be sunk in Florida, where it will join tens of other artificial reefs, and the idea is it would attract tourists, bring economic benefit to the area, and also perhaps encourage...

encourage divers not to visit some of the other more natural reefs. So kind of moving that tourism away from more precious environments like real coral reefs. What is the process going to involve in order to prepare this ship, this ocean liner, so that it becomes an artificial reef? So it's quite a long process from beginning to end. This one will take one and a half years. That's because, as you can imagine, it's full of

contaminated materials. It's got metal, plastics, oils, chemicals and they want to clean those out, remove all our material, take away the paint.

They then also have to begin the process of sinking the ship. And it is as simple, in the past anyway, as basically exploding the ship. So I looked into some of the previous ships, so aircraft carriers have been sunk there as well, and they basically load the bottom of the boat, which is underneath the water, with explosives, blow them up, and then all the water, of course, comes into the bottom and it sinks.

That, for this ship, for the SS United States, will cost about $10 million. Some studies say that within five years you can have an increased number of fish, you can have coral and algae growing over all of those surfaces. You mentioned that this particular ship is going to go through a very meticulous preparation process to remove some of the contaminants. Is there a risk that it still could be toxic or polluting to the environment? Yeah.

Yeah, I mean, I think it's a really good question. In the US, it appears to be quite a well-regulated industry. There are whole companies that are set up just for this process. And that process appears to involve quite a lot of care. You know, they do decontaminate it, they take away those chemicals. But of course, there's always a risk that the job hasn't been done properly. There are some people who are really unhappy about the fact that this ship is being sunk because as you set it out, it's this incredible old ship

piece of history essentially and some historians not necessarily environmentalists they would rather that it becomes a museum is making artificial reefs do you think just a way for humans to get rid of waste items things like big old ships that are otherwise really difficult to get rid of

See, I actually think that it's probably quite an inconvenient way of disposing of a ship because it's a very involved process. I said earlier that this one, the SS United States, will cost around $10 million to turn into an artificial reef. You've got all of the cost of the decontamination, but also a lot of those materials could have been sold off. Scrap metal is very valuable now. But

But I think you're right that it's quite controversial in terms of, if you look at the pictures of it, it is kind of a stunning ship. You know, it's a bit aged now and a bit decrepit. But it did have incredible historical value. The company behind it would say, well, this is a way of preserving its legacy. And at least they say it will have some value on the seafloor. Do you think that we still need to be putting more stuff on the bottom of the ocean? Do we not have enough stuff down there already?

So I think there is a lot of, like you said, there's a lot of stuff down there. There's around 3 million shipwrecks and similar wrecks on the seafloor. But the ocean is a vast part of our planet. It covers a huge area of the surface of the Earth. So I think we're probably not going to run out of space anytime soon. I think the main question is, is this really the best way of trying to protect marine species who are at threat from global warming and pollution in the oceans?

I think lots of environmentalists would say we should be focusing on the environments we already have and protecting those rather than trying to create this mixture of a bit of tourism, diving, plus a

a place for these species to live. And it's not just ships. I was reading about aeroplanes, even New York subway cars, lots of different things that have been sunk to create artificial reefs. One study found that artificial reefs cover 19 square kilometres, that's seven square miles of the US seafloor. I mean, that's tiny compared to the size of the sea and the oceans. What works best when it comes to sinking things to make artificial reefs?

So I was quite surprised when I was looking into this at just how many there are. In some countries, I think in Japan, they've been doing it for 400 years because by creating a new environment for species, they can attract fish and obviously then they can fish there. And in the US, it's been going on since the 70s.

What some of the research says is that you need to use materials that are good for the environment, they're safe, they're pH neutral, so you're not changing the chemistry of the ocean. You're not using contaminated materials anymore.

There was a case where they sunk three million tires in the 1970s with the idea, again, you would create this space for fish and octopus and everything else to live in. And that didn't work and it released a lot of toxins into the environment and they weren't anchored properly so they moved and it damaged some of the coral in the

in that area. So clearly, it has to be done in the right way. And it is not just forms of transport, shall we say, old disused items. There are lots of reefs, in fact, the majority of them that are specifically made for this purpose. Can you tell me a bit about them and how they're different to the ones that we've been talking about?

Yeah, so there are lots of different types, but one of the ones I particularly like is one in Mexico in the Cancun Marine Park, which is called Musa. And that one was established because the founder said that he was concerned about the level of degradation and pollution on some of the natural coral reefs in that area. And he wanted to try and pull some of the visitors'

to those corollaries to a different place. Now there's 500 sculptures and they include sculptures of people, but also there's a Volkswagen car that's been sunk. And that is clearly, you know, it's a very deliberate project. They've made these structures and they're made of particular types of material that are considered beneficial or neutral to the environment.

That one is one project, but it's also a practice that's used to protect seagrass meadows or coral reefs where they build, they're kind of, they look like these sort of

cones and they've got holes in them so you can sort of imagine the species moving through them. Some of them are done in order to protect coastlines from erosion or from huge amounts of sand that move in storms and then the secondary effect is that it creates this reef for species to live in. So there are lots of different types. So is there any evidence that these artificial reefs, whether they're these amazing statues that you've described or sunken ships,

Is there any evidence that they actually help the ocean and ocean creatures?

So we don't really know what the long-term impacts are. They're quite difficult to study because you can't control the variables. So you don't know if because you sank that ship or that car that those species have moved there. There are quite a lot of studies that show that in the short term you do have a bloom of life. So fish do move there, they colonize. That creates this nutrient cycle, for example, that generates plant growth and coral growth there.

But there are also examples where non-native species can colonize the area because it's obviously not a natural environment. So it might attract invasive species, invasive fish, and that obviously has a knock-on effect on the environment. There was another case in Puerto Rico where a concrete reef was created to protect the coastline. And in the short term, there was a growth in fish and in coral, but

But there was also a bloom in seaweed because of this imbalance in nutrients. There was too much oxygen and therefore there was excessive nutrients and that led to some of the coral to die. And there's also concerns that that moves them away from more natural environments where you have a sort of proper functioning ecology.

And you may be disrupting that by placing these artificial structures there. Although, as you say, it also moves the tourists away and that could in the longer term help some of these corals that might be a little bit over visited. Absolutely. I think that's one of the main reasons that people want to do it. It's the idea that if you've got this one beautiful coral reef and everyone's going there, why not try and divert them almost by creating a different environment there?

But I think in the long term, you can't replace coral reefs with artificial reefs. That's not how the environment works. And so you need to maintain both. You may want to focus on those as a diversion for tourists, but I think a lot of environmentalists would say we still need to protect our coral reefs and make sure that they're not going to die out with increased pollution and ocean warming. ♪

Georgina, thank you so much for coming into the studio. Thanks, Hannah. And thank you for joining us. I'm Hannah Gelbart. This is What In The World from the BBC World Service. And we'll be back with another episode soon. See you then.