As a child, Mário Soares ventured into a mangrove in the Guaratiba neighborhood of Rio de Janeiro for the first time. Throughout his life’s journey, this place remained with him. After graduating in oceanography and conducting research on a mangrove crab species in Sepetiba Bay, Soares decided to shift his focus to ecosystem ecology. During his doctoral studies at the University of São Paulo, he returned to Guaratiba to study the mangroves of the region and later served as the chief of the Guaratiba Biological Reserve.

Today, with more than 30 years of experience studying mangroves, Soares is a professor in the Department of Biological Oceanography at Rio de Janeiro State University and leads the Mangrove Studies Center (NEMA). Here, he has conducted pioneering research in Brazil on the impacts of climate change on mangroves and their role in carbon sequestration.

Through NEMA, he adopts a transdisciplinary approach to mangrove research, collaborating with fields such as chemical oceanography, geography, political science and anthropology. As a result, he engages in applied science, working closely with environmental managers, and over the past 15 years, he has also delved into socioenvironmental conflicts in diverse contexts across Brazil.

Soares recently talked with Mongabay in a video call. The following interview has been translated from Portuguese and edited for length and clarity.

Mongabay: What is the importance of mangroves in mitigating climate change?

Mário Soares: The importance of mangroves isn’t solely about mitigation. Because when we discuss mitigation through mangroves, carbon sequestration often takes center stage — they capture a great amount of carbon — but that’s just one form of mitigation. Another form is by reducing the vulnerability of coastal zones. This is one of the criticisms I have about the carbon issue — mangroves are often generalized as mere carbon sinks, when in reality, they serve various other functions.

For instance, they act as natural barriers against storms. Coastal areas associated with mangroves are much more protected, resilient and less vulnerable to storms and extreme events, which are some of the consequences of climate change; they also function like riparian forests, acting as sponges and reducing the likelihood or effects of floods in the coastal zone.

There are still other functions related to reducing vulnerability. For example, by providing various services to the communities that exploit [a mangrove forest] for fishing, it is supplying goods and services that are essential to keeping these people less vulnerable in scenarios of scarcity.

Mongabay: And conversely, how can climate change impact mangroves?

Mário Soares: Now, being a natural system, mangroves are also vulnerable to climate change. So what I always emphasize is that there’s a feedback loop — for mangroves to fulfill their role in reducing vulnerability and mitigation, we need to help reduce their own vulnerability. In other words, if we don’t work to perpetuate them, their role in reducing vulnerability will be compromised.

Therefore, we must reduce their vulnerability so that they, in turn, can reduce the vulnerability of the coastal zone. We’re talking about a forest system within the region we call the intertidal zone — between low tide and high tide. So, the first thing we observe is that they will primarily suffer from sea-level rise, and if the sea level rises rapidly, they will either drown or adapt. One way for them to adapt is by relocating within the coastal zone; it’s as if the entire system migrates as the sea level rises.

This has been happening, and we’ve been monitoring the mangrove forest for this purpose for 25 years. There’s an area in Rio de Janeiro within the Guaratiba Biological Reserve that wasn’t a mangrove [forest] 25 years ago; today, it’s a mangrove forest. It used to be an area behind the mangrove. However, for this process to occur, you need long-term coastal zone occupation planning. There’s no use in building a road, a city or an industry behind it because the mangrove won’t be able to adapt. Therefore, we need to keep these areas reserved so they can accommodate themselves, and then we can benefit from their existence.

Similarly to how they protect the coastal zone from extreme events, they are vulnerable to such events. In areas prone to hurricanes and storms, mangroves are often destroyed. However, this doesn’t mean they cannot recover. In fact, when destroyed, they are actually self-sacrificing for the coastal zone because they dampen the impact of the storm, acting as a barrier and preventing direct confrontation with what lies behind the mangroves.

They are susceptible to changes in climatic conditions such as shifts in rainfall distribution and intensity. As a forest ecosystem, mangroves rely on freshwater, and one of their primary sources is rainfall. While a wetter climate may be beneficial, it could also become drier, more arid and hotter. Therefore, mangroves will also feel the effects of these changes in terms of precipitation, temperature and freshwater availability in the region.

Mongabay: One of the main arguments used in favor of mangrove conservation is to highlight their high carbon sequestration capacity. What could be the limitations and problems of this approach?

Mário Soares: The first thing we need to be clear about is that we’re subjecting the system to market logic. I remember when I started studying mangroves, carbon was just carbon. Nowadays, you open your computer and find various carbon prices on the Internet. Simply put, we’re trying to solve a problem by applying the logic that created it — the market logic — and nobody solves a problem by applying the same logic that created it.

The second issue is that the carbon market doesn’t address the problem; it only tackles the symptom. In other words, we’re not reducing emissions. In fact, what we’ve seen is an increase in emissions, and in a way, we’re granting permission for emissions to continue, under the condition that they are offset by sequestration in another system.

And with this trend, there has been a rush of people looking for areas to plant mangroves. Moreover, I have seen mangrove planting projects in areas that were not originally mangroves. Because it became a trend, a business opportunity and a possibility for projection for governments, for NGOs, researchers and companies. In other words, it’s visibility, prestige and access to resources.

Furthermore, I have observed a growing harassment of traditional communities. Simply put, communities being pressured by companies, NGOs, forest planting companies, carbon credit companies and certifiers. And some of these projects do not respect the livelihoods of these communities.

On the other hand, planting is always good, but this is not the solution to the problem. That’s why in the [COP28] policy briefing [published in 2023], we emphasize that before planting, we need to reduce emissions. But the restoration of areas that need to be restored is always welcome.

Brazil’s mangroves, despite historical reduction — some areas are even recovering, such as some areas in Rio de Janeiro — 80% of our mangroves are in protected areas, so we need to protect them. In my view, the fact that mangroves have a high amount of carbon compared to other systems shows the importance of mangrove conservation.

We have a system that contains a large amount of carbon; if we destroy this system, this carbon is released into the atmosphere. So, the focus is on the avoided emissions. We have to demonstrate the importance of having resources and funding for the conservation of systems or for the recovery of those that need to be restored.

Mongabay: Currently, what are the main threats to mangroves and the communities that depend on this ecosystem?

Mário Soares: We’re usually referring to traditional communities, and we’re talking about a vast diversity of groups because mangroves occur in Brazil from Laguna in Santa Catarina [in the south] to Oiapoque [in the north]. A traditional community living in Pará is entirely different from one living in Laguna. You have everything from caiçaras in the south and southeast, quilombolas, indigenous peoples from coastal regions, riverine communities, and many others who live associated with mangroves.

But mangroves are not only benefiting them, they are benefiting us as well — when it sequesters carbon, it’s sequestering it for everyone; when it protects the coastline, it’s protecting not only the traditional community, but also the city nearby. And when someone fishes, they’re not just fishing for subsistence, they’re fishing for you, too, who eats the fish.

Many people say, “This is not my problem.” It is indeed our problem, when you destroy a natural system like the Caatinga, like the mangrove, which has a community who depends on it, and that community becomes vulnerable, or that community migrates and becomes a sub-society within a nearby urban center, then it affects you indirectly, or it will be supported by social programs that come from our taxes, so it concerns all of us.

So, when we talk about threats to these communities, I’m talking about the major threats to Brazil’s mangroves — urban expansion — and this affects the entire Brazilian coastline — sewage, garbage and oil exploitation. I’m referring to the entire oil chain — because the main source of oil in Brazil is offshore — from exploration, transportation, whether by ship or pipelines to handling and refining. We’ve had accidents with ships, platforms and pipelines. So, this is also a widespread problem. When I talk about urban expansion, we can also include the tourism sector in this account.

And in the northeast, we have an extremely serious problem, which is the exploitation and destruction of mangroves for the establishment of shrimp farms. It’s the same problem we observe in the rural areas of Brazil because it’s a style of agribusiness that not only destroys the environment but also creates strong socioenvironmental conflicts. We have been working extensively with these people in this case since the 1990s. It’s a problematic sector because it has strong lobbying and land concentration.

The coastal zone is a prime area for the establishment of tourist enterprises and often the same area where you will have cities, major urban centers, ports and industrial hubs because mangroves occur in sheltered areas — in lagoons, bays and estuaries.

Mongabay: What specific initiatives does NEMA undertake to involve local communities in addressing environmental concerns?

Mário Soares: We have been working extensively with communities, not only in knowledge production but also in supporting their struggles. A very emblematic example: When there was an oil spill on the Brazilian northeastern coast in 2019, we had a government that showed no sensitivity to tackle the issue. So, the confrontation was being led by local communities, residents, NGOs and some scientists. While I saw some colleagues already eager to gather data, thinking about publishing articles when the oil was still in the water, I attended a general forum and articulated a project with local communities from an extractive reserve in Bahia.

We made available to the communities an organic geochemistry laboratory, which is our partner within the oceanography faculty, because I told them: We have to try to contain the oil, but soon you will face a food security problem. So, we have to think about that in the future: They will prohibit you from consuming and selling fish because they don’t know if it’s contaminated. I said: We will make available to you a laboratory that performs this analysis. So, we provided the laboratory, the researchers and the technicians. And then I said they would be the ones to design the sampling — you will say where and what we will collect, which places you fish and what you fish.

So, they defined: “We have these fish, these mollusks, and these crustaceans.” A team went there to collect with them and brought all the material. We did the analysis with the participation of the fishermen, and thankfully, nothing was contaminated; they could consume and sell. Two years passed, and then we wrote the article, and one of the fishermen is a co-author of the article.

Of course, he won’t be discussing analytical chemistry. But he had a role in the development of the study. So, it’s an example of how we approach it. What I preach a lot to my students is that there is no knowledge more important than the other — they complement each other.

Mongabay: Why are mangroves particularly vulnerable to oil spills? What is the potential extent of their impact?

Mário Soares: There is a table that was developed in the 1970s and used by the National Oceanic and Atmospheric Administration (NOAA) with a sensitivity scale from 1-10. And the mangrove is rated as 10, considered most sensitive to oil. There are several reasons. First of all, it’s because of its ecological importance in terms of productivity, maintenance of biological diversity [and] the fact that once affected, you have no oil removal strategy. Why not? Because that’s a forest with mud. You can’t bring in machinery, and if people enter there, they’ll trample, making the oil penetrate even further into the mud. Unlike when this happens on the beach, where all the sand is removed and thrown away, or like on the rocky shore where blasting is done.

When the oil enters the mangrove, it can remain there for decades. There are two ways the oil is removed: by tidal washing, and for it to be degraded by the microbiota. Because oil is nothing more than organic matter. And like any organic matter, it can be degraded by bacteria. This allows for the possibility of biological removal through degradation. But in the mangrove, we have mud with very little oxygen concentration. So the degradation of organic matter there is slower. In addition, that mud already has a lot of organic matter. That’s why when we enter the mangrove and smell a rotten egg odor, that’s organic matter being degraded anaerobically.

Oil will compete with the natural organic matter for degradation by the microbial community. So, besides being a sensitive environment due to its importance, and besides there being no effective and efficient methods of cleaning the oil that falls in the mangrove, the oil tends to degrade very slowly.

A doctoral student who did her thesis with petroleum hydrocarbons collected sediment layers in Guanabara Bay, analyzed the oil hydrocarbon and dated it, so we were able to reconstruct the last 100 years. She found in the middle of this sediment core oil from a spill that occurred in Guanabara Bay in 1975. It’s there, we see the 1975 spill, we see the 1997 spill, and we see the 2000 spill still in the sediment. So it can take decades for the mangrove to recover, and the oil remains there.

Mongabay: Recently, you participated in a research project in the mangroves of Brazil’s northern coast. What characterizes and makes this mangrove belt so special?

Mário Soares: In fact, it’s not more special than other mangroves — all of them are special and important. On a national scale, 80% of Brazilian mangroves are on the northern coast. So, it’s the largest mangrove area in Brazil, an extensive area; from Maranhão to the mouth of the Amazon, we have the largest continuous mangrove area on the planet.

Moreover, we have several extractive reserves there, meaning various traditional communities use those mangroves, but not only them; there’s an entire fishing production chain that depends on them. So, they have a very strong economic role, with tourism also associated with these mangroves. If you go to some areas in Pará, you’ll find a huge sports fishing chain, tours, tourism, education — there’s a great diversity of uses in these mangroves.

Mongabay: Can you provide an overview of the project you participated in, focusing on mangroves along the northern coast of Brazil?

Mário Soares: It was a project that involved many laboratories and was coordinated by an oceanography company. We studied mangroves from Maranhão to Amapá, and there are areas in Amapá that take about four days to reach from Rio de Janeiro to the work area.

Field studies consisted of measuring vegetation, placing sensors for data collection of tides and circulation, remote sensing by satellite with high-definition images and lidar. And we developed a new modeling in the country.

The project’s objective was to propose a new methodology for mangrove vulnerability to oil spills. All the mangrove analysis with oil is based on this [NOAA’s] sensitivity table, where mangroves have a sensitivity of 10. And what we advocate is that mangroves are not homogeneous, they are unique. So if you fly over the mangroves, you’ll see a homogeneous forest, but if you go inside, it’s totally different. Its sensitivity is different if the mangrove is close to the sea, if the mangrove is closer to the land, if it is more washed by tides. So the first challenge of the project was to make an approach that we called infra-systemic. It’s to say that mangroves, at that scale, have a sensitivity of 10, which is high, but what we argued is that there are mangroves that have even higher sensitivity. So we already started at this high sensitivity scale. Very high and extremely high, that’s what we reached, so we wanted to show that it wasn’t homogeneous. That was the first point.

The second point, we wanted to show that vulnerability is often conceptually used in different and mistaken ways. Sometimes you’re talking about vulnerability, but you’re actually talking about sensitivity or susceptibility. So, we argued that vulnerability is divided into three components. But it’s important to first understand that vulnerability refers to some agent. People often say, “It’s vulnerable to climate change.” That’s a void because climate change can be sea level rise changes, it can be changes in rainfall, it can be vulnerable to sea level rise and not vulnerable to storms at the same time. So by defining the agent — in our case, oil spills — you have sensitivity, which is how much the system will feel the effect of that agent if it is hit by it. In other words, how sensitive I am to this agent. This is the first component.

The second component is susceptibility, which is the probability of being hit by the agent, in this case by oil. The probability we calculated through a probability model. It’s the probability of oil that comes out of one point reaching another point.

And the third component of vulnerability is resilience, which is the ability to recover. In other words, your response to the agent. What is your ability to recover if you are hit by oil.

Mongabay: During your lecture at the National Mangrove Conference, you mentioned that on the northern coast “you need to bow to the forces of nature that regulate your entire work process.” What are the major challenges of working in a region like this?

Mário Soares: When you go there and end up like we did on a small boat adrift practically off the coast of Marajó Island at the mouth of the Amazon River, you see that it’s not easy.

In addition to talking about an enormous area of thousands of kilometers, a belt of mangroves that extends from Maranhão to Oiapoque, there’s a system which has a really strong current that flows from east to west; we have extremely high tidal amplitudes, which we grow up hearing about in school, the Pororoca.

The tidal amplitude, which is the difference between low tide and high tide, here in southern Brazil is less than 2 meters [6.5 feet], meaning the tide oscillates less than 2 m. There, we’re talking about 8-10 m [26-33 ft]. That’s a lot of energy.

Additionally, there are huge rivers flowing, and depending on the season, a great amount of rain. The rainy season on the northern coast of Brazil — it’s crazy, because you have a huge current system, suddenly the tide rises, suddenly the tide falls. And in the late afternoon, it starts to rain, you look at the ground, you see the water evaporate — there’s a lot of energy.

Those who advocate for oil exploration in that region say, “But technology has improved.” It’s not a matter of technology. It’s natural forcing, an enormous area with great energy, and if we can’t decently contain an oil spill within Guanabara Bay, a confined space, without any of these energies I mentioned, we’ll never be able to contain it. We don’t even have enough equipment to contain such a thing over such a large area.

There’s also the aggravating factor that I mentioned to you, which is the extremely strong east-west current system; it has a strong additional aspect of international politics. Depending on the area where oil is being exploited, any oil spill can affect neighboring countries, it can affect French Guiana, Guyana, Suriname, Venezuela and even some states in the Caribbean region because of this oceanic circulation system. So it’s not just a Brazil issue. It’s a matter involving international relations, a serious problem in diplomatic terms.

It’s not a matter of if there’s an oil spill, it’s a matter of when. It’s a fact, it always happens. And there’s a lot at stake. We’re putting many other sectors of the economy and society at risk. We think that selling it will generate wealth. It may generate wealth for some sectors and in a punctual way. But just look at the areas where the oil sector has settled and you’ll see the amount of social and environmental problems that come with it.

Banner image: An Amazon kingfisher (Chloroceryle amazona), one of the birds that can be found in the mangroves. Image by Martha de Jong-Lantink via Flickr (CC BY-NC-ND 2.0).

https://news.mongabay.com/2023/08/video-rio-de-janeiros-defender-of-mangroves/

Citation:

Comte, A., Cormier-Salem, M. C., Guillotreau, P., Manouvrier, S., Proisy, C., Chabrol, R., … Agraz Hernandez, C. M. (2023). Blue carbon credits: a lot of promises but even more uncertainties for the Global South. COP28. UAE. Retrieved from https://hal.science/AMAP/hal-04425664v1

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