Mussels, Kelp, and Climate Resilience: One approach to tackling ocean acidification

Corinne

Welcome to another episode of "Salty Talk: Conversations on Sustainable Aquaculture in Maine." I'm your host, Corinne Noufi, the communications specialist at the aquaculture research institute, here to bring you another interesting conversation that delves into a crucial topic surrounding our marine environments and the communities that rely on them. In this episode, we're taking a close look at a pressing environmental issue: Ocean Acidification. This global phenomenon is having notable impacts right here in the Gulf of Maine, affecting our marine ecosystems.

To help us navigate this complex topic, we have the expertise of Susie Arnold from the Island Institute. Susie is a brilliant voice in this space, working towards understanding and mitigating the impacts of ocean acidification, and fostering sustainability in coastal and island communities.

Throughout this episode, we'll unpack the details of Ocean Acidification, examining its global ramifications and its specific repercussions in the Gulf of Maine. But it's not all concerning news. We'll also be talking about potential solutions, particularly focusing on the role of kelp farming as a sustainable alternative and its potential to bring about positive changes in the marine environment.

Susie

So my name is Susie Arnold. I'm the senior Ocean scientist and the Director for the Center for Climate and Community at the Island Institute. The Island Institute is a nonprofit community development organization based in Rockland, Maine. I've been here for eleven years. This was my first job out of grad school. I went to the University of Maine and got a dual master's degree in Marine Policy and marine biology and then stayed on and got a PhD in marine biology. My PhD was all about coral reefs and how baby corals get started on reefs and the importance of certain species of fish to make that happen. So this was a bit of a shift from a tropical ecosystem to something that is closer to where I grew up. But it was a great fit for me because of the link between healthy fisheries and healthy communities. That was something that I really learned through grad school very much in the tropics, coastal communities that live adjacent to coral reefs are very much dependent upon healthy coral reefs for their source of protein. So I liked that link between healthy communities and healthy ocean ecosystems, and I've been really able to focus on that throughout my career here at the Island Institute.

Corinne

It's always refreshing to meet someone who echoes the beliefs that have guided my own career path. Susie's words resonate with me, taking me back to the times when I was doing fisheries research in Cambodia. There, amidst the day-to-day life of the local communities, it was evident how their well-being was so intricately tied to the waters that surrounded them, which Susie eloquently stated… that healthy communities are intricately tied to healthy fisheries. When the marine life thrives, it creates an almost ripple effect, positively impacting everything from the local economy to the nutrition and livelihoods of the individuals in the community.

It was great to hear Susie channel her experience and expertise into nurturing this link right here in Maine. And it's a reminder of the universal truth that, be it in the vibrant waters of Cambodia, the coral reefs, or the Maine coast, understanding our reciprocal relationship with the ocean is so important. Before diving into the bulk of the episode I did want Susie to answer, what exactly is the island institute?

Susie

So the Island Institute is a community development organization. We've been here in Rockland for 40 years. We focus primarily on Maine's 15 year round unbridged island communities, but also work with all of the coastal communities in Maine. So our mission is to sustain these island and remote coastal communities so ensuring that they have access to the services that they need to maintain year round communities. And because some of these coastal and island communities have such a high dependence on fisheries, that's why a scientist who specializes in marine science works at the organization.

Corinne

And by unbridged island communities, do you mean like Vinal Haven or North Haven?

Susie

Yes, exactly. There's tons of islands that are connected to the mainland by bridges here in Maine. Those that are yeah, georgetown, even Arousic. Well, I guess Arousic is not. No, Arousic is you do have to go over a bridge to. Get to Arousick and then another bridge to get into Georgetown. So, yeah, there's lots of bridged, island communities, but those that are accessible only by boat are vulnerable to a lot of things that islands that you could drive to are less vulnerable to.

Corinne

As Susie elucidated, these communities accessible only by boat are particularly susceptible to an array of challenges. As we continued our conversation the term 'ocean acidification' started reverberating in the dialogue. This phenomenon, often murmured in environmental circles, holds a complex narrative of its own, we toss this term around so often it’s almost engrained in our natural vocabulary, but what exactly odes ocean acidification mean and what are it’s implications?

Susie

units since, let's say,: 1800

Corinne

Susie’s delineation of the process, how carbon dioxide forms carbonic acid in the seawater, altering the pH and disturbing the building blocks vital for shell formation, is not just a narrative of changing chemistry but of changing Maine's marine ecosystem. This process, is no longer diagram confined to the pages of scientific journals, but a looming reality with consequences that could span generations and geographies. So what is the border implications here for our shell builders? how do these chemical changes translate to the life of a mussel for instance?

Susie

Yeah, so it kind of depends on the species. But it can be more energy has to be put into that shell building process, so there's less energy available for things like reproduction or maybe that shell ends up being thinner, and then it's more susceptible to breaking. Mussels hang on through these things called bissell threads. That's how they hang on to the rocky intertidal or to the line that they're growing on. And research has shown that those bissell threads are vulnerable to increased acidity, so they might not be able to hang on as well. So there's lots of different ways that acidification can impact shell builders, and we certainly don't know the extent of it.

Corinne

There has to be some hope though? Susie, in collaboration with Nicole Price at Bigelow labs must think so, as they look into the potential that lay within the waters of the Gulf of Maine - a potential stemming from the versatile nature of kelp. I absorbed Susie's words, hearing a description of the symbiotic alliance between kelp cultivation and shellfish farming, mussels in particular, potentially carving a new pathway in the face of looming challenges. So, how does kelp manage to create a remediation halo that seems to be fostering a healthier environment for our mussels and potentially other shell builders?

Susie

able to tell people going out: 2050

Corinne

So exactly how big IS this halo effect?

Susie

That's a great question and that's something. That is so dependent upon tides and currents and flow, we weren't really able to nail it down. So we measured using shipborne instruments. So basically instruments that were towed beneath a small vessel that were taking measurements of parameters that determine ocean acidification in real time. So we just drove really slowly. The first year we kind of did transects out from the farm, and the second two years, we did concentric circles around the farm to see if we could map this, to see if we could map the remediation halo. And that proved to be really difficult because as the the tide moved, even during the day when we were measuring, you could see it wasn't as straightforward as you might think. So I guess the answer is it's highly dependent upon the site, so every site is going to be different. We were talking about that work that happened out in Washington state, in the Puget sound. A similar study was done out there in an. Location with very, very strong currents. And I think this concept may not work in a location like that, because the water currents are just so strong that they would essentially wipe away the remediation halo so quickly that it wouldn't be like growing shellfish in, like, a bathtub of less acidic water. It would just immediately be dispersed by the current.

Corinne

As I absorb Susie's words, my mind drifts to the estuaries and expanses of oceanography I am more familiar with back on the west coast, specifically in the dynamic waters of Puget Sound. I find myself pondering the unique characteristics of places like the Hood Canal, where efforts have been undertaken to cultivate kelp. The waters there are different, marked by distinctive currents and tidal patterns. I can't help but wonder if the strategies that Susie discusses would find the same foothold in starkly different marine dynamics, such as puget sound or elsewhere, harboring the potential to benefit from kelp as a remediation strategy?

Susie

That's our goal with having our instruments at Bangs Island now is to try to help determine basically where they put the kelp around the muscles to get the best remediation benefit from the kelp for those muscles? So exactly. That understanding. How the water moves at that location and where to put those kelp lines. I suspect in an area of really high flow where you always have the current moving really rapidly, that even if you had a ton of kelp upstream from the mussels for the majority of time, I think that that halo would be so short lived in ephemeral that you wouldn't be able to see a benefit. So I think it does require kind of enclosed bays where this would actually work. And obviously the more kelp you have, the better. But I think just determining that ratio and the site set up is exactly what we're trying to do now.

Corinne

Given all these dynamic variables, how farmers could adjust their strategies. Does the species of kelp matter? What about proximity of mussels to the the kelp or the seed density?

Susie

Yeah, I think kelp farmers have been experimenting with just that. How close you can put your lines? Is it 10ft? Does it have to be more? Can you seed them more densely? What are the pros and cons to doing that? How much nitrogen is available throughout the whole season to allow for sustained growth? When do you have your phytoplankton spring bloom occur that then takes up some of that nitrogen and makes it less available for the kelp growth? So there are a ton of factors to consider to kind of maximize your kelp harvest and also the phytoremediation benefit of the kelp. I'd say for now, I think farmers are very much focused on maximizing their kelp harvest over any benefit it might provide for their muscles. But we only have currently, I think, well, now two mussel farmers who are also growing kelp. Yeah. There's tons more research to be done to try to nail down how much kelp is needed, what are the exact benefits that are being provided to the mussels? Also, there's a possibility that the biomass that sloughs off of the kelp might then also be an additional food source for the muscles. So there could be more than just the chemistry benefits for colocating those two species. Nicole Price had done an early lab study comparing, I think, four species of seaweed's ability to take up carbon dioxide. And the kelp species she used in that experiment was sugar kelp. And it was found to be far superior at taking up carbon dioxide through photosynthesis than the other three species. 1s As you know, there's sugar kelp and skinny kelp that are being grown here in Maine. I think they both provide a similar benefit, but we have not tested that because it really depends on what the farmer's growing. And I don't even know the I couldn't tell you right now the ratio of skinny to sugar that was at the farm that we were testing in the early years, it was 100% sugar kelp. Right now, I'd have to look back at the different years of whether there was a mix of those two or if it was all sugar kelp

Corinne

My mind drifts to the broader panorama of Maine's aquaculture. Could this work for other marine organisms we farm or fish in Maine like oysters or lobsters? How do we choose what species we should farm in tandem with one another?

Susie

You have to think about if you're pairing species and you're looking for that phytoremediation benefit of a photosynthesizer, you need to pair species that grow in the same habitat. So, for example, it kelp and mussels Are a good pairing because they are both aquaculturists who are looking for a site to grow. Both of those will be looking for somewhat similar characteristics approximately 30 plus feet of at least 30ft of water, probably more if you're growing mussels. But the deeper you go with a kelp farm, the more line you need, the potentially more rough it could be. So I guess what I'm getting at is that pairing works well for those two species. It would be a little bit more challenging, I think, to. Grow kelp around oysters. Oysters typically are found in a little bit shallower water than you would ideally grow kelp in, and so that pairing might not be as applicable.

Corinne

So you could do scallops then, or yeah.

Susie

Yep. Potentially could do yep. Nicole was looking at other pairings of marine vegetation and shellfish, and she was looking at the ability of seagrasses I was just about to ask yeah. To improve water chemistry in an enclosed bay that would be a place where softshell clams are found. there's lots of room for eel grass restoration here in Maine. We also have a huge problem with the invasive green crabs that are decimating the eel grass. It is so they eat the rhizomes of the eel grass and they also eat the soft shell clams. And so thinking creatively about how we deal with that in combination with making it so that eelgrass restoration can be successful is really important. So there's that potential pairing. She's also looking into the ability of rockweed to be grown in close proximity to oyster farms. Both rockies everywhere. Yeah, there's rockweed everywhere. So there are other potential pairings that could work with marine vegetation and shellfish. But to get back to your question about lobsters, I can't envision something that would work similarly. I think lobsters are kind of extra vulnerable to acidification because of the habitat where they're found, and the Gulf of Maine is shifting to a lot of invasive seaweeds that are kind of decaying on the seafloor, causing inoxic more acidic environments where at least juvenile and adult lobsters are found. And then you've got different issues for larval lobsters that are kind of being carried along the surface where you have surface acidification happening. So there's a lot more room for studying how acidification and other climate factors are impacting lobsters and what potential solutions could be.

Corinne

Listening to Susie, I find myself drawing parallels to my own experiences back in Washington. As susie talks about other potentials like eelgrasses and rockweed, and the various localized site characteristics that play a crucial role, It reminds me of the vulnerable eel grass habitats I have encountered before in the Tacoma Narrows. The vulnerability of those habitats seemed to mirror the challenges Susie was depicting. Could the learnings from one coastline engage conservation strategies of another? . The scope of this project seemed to me, to be so intertwined with the distinct characteristics of the local marine environment. It seems there's potential for an expansion of this concept beyond Maine, possibly crafting a global narrative on marine conservation and farming

Susie

Yeah. So one way to kind of get at your question about how do you design your farm for the Best phytoremediation benefit for these mussels? And one way that we're investigating this is by partnering with farms in Norway and Alaska, where they're deploying the same instruments that we have here in Maine at their locations to see if they can measure an impact from the kelp that they're growing 2s in their location to see if we can get a better sense of what environmental characteristics are needed for this design to work. Essentially, we know it's not going to work everywhere, but when you have 1s a three knot current on a regular basis, is that something that is not going to be an option? Or getting at some of those more 1s localized site characteristics to determine if a farmer could actually use this strategy or not?

Corinne

So that's just getting, like, a wider data set outside of what you can get in Maine because they have very different coastlines.

Susie

Yeah, they have different coastlines and just. Sharing our successes with others and trying to test this concept in other places in the hopes that it will work and then it will take hold and it will be a localized adaptation strategy for shellfish farmers.

Corinne

Thinking about shared knowledge and implications in Maine, I might think the evolution from concept to practice could be a challenge to navigate for those in the industty.

Susie

Yeah, I mean, I think there are not a lot of commercial mussel farmers in Maine. There's what, about five major companies? And I think the big bottleneck for muscle farming is upfront costs of muscle rafts and just equipment. So I think 1s that's one of the big bottlenecks is it's really hard to start a mussel farm in Maine. And so this strategy is most applicable to a mussel farm. We've got hundreds of oyster farmers. The strategy is less applicable to that species. So I think that how are mussel farmers finding out about it is word of mouth. There's not that many businesses, so I think they're in pretty close communication. So I think one thing that would be helpful is to help mussel farmers get past the barriers to starting or expanding their farms.

Corinne

these barriers and challenges highlighted by Susie, I thought back to ocean acidification. Could there be a discernible impact economic bearing down on the mussel farmers, tied to the rhythms of the ocean's changing chemistry?

Susie

I always think back to watching a mussel harvest. If you've had the opportunity to see how mussels are harvested in Maine, it's a fairly rough process. There's a lot of shoveling, there's a lot of tossing, there's a lot of metal equipment, and there's a lot of opportunity for shells to break. And the way I think about it is 1s if if those shells can be just that much stronger because of this strategy, that will lead to less breakage and more money going straight to the farmer instead of a dead mussel being tossed off the barge. So no one has quantified 3s how that equates to a mussel farmer's, bottom line, to my knowledge. But 1s that kind of image is always in the back of my mind about, well, if we could have a third less breakage because the shells are a little bit thicker, then that would be a huge win for a mussel farmer. That would be super interesting to somehow get the numbers behind that, looking at landings like from Bangs Island before they had kelp and then yeah, I think there's so many different there's so many different environmental parameters that. Go into a successful season that I think it would be really hard to quantify. But it would be really interesting to think about the pandemic happened, right?

Corinne

While talk of ocean acidification and everything else can sometimes seem grim, I did want to end on a high note, looking more towards a horizon brimming with opportunities and hope.

Susie

I think just maybe one thing I'll end on that is exciting and hopeful is that beyond Kelp's ability, to remediate ocean acidification at a really local scale. There's a lot of research happening in Maine around the broader climate services that seaweeds can provide. So I think that that's really exciting. And it's exciting that that work is happening in Maine. You've got Bigelow also looking at Seaweeds being specifically sugar, kelp being used as a food additive for cows to reduce methane emissions. There are companies in the United States looking at kelps being used for bioplastics biofuels. So I think it's really encouraging that. 2s Folks from Maine, from the United States and around the world are investigating all the potential climate services that Seaweeds could provide, either through replacement of other more high carbon products or through things like remediation of ocean acidification. So a lot of excitement around Seaweed and a lot of research to be done, but a great opportunity for Maine to continue to expand seaweed farming.

Corinne

A big thank you to Susie for lending her expertise to this vital conversation of ocean acidification mitigation, where the kelp and mussels may hold innovative localized solutions.