“My bounty is as boundless as the sea, my love as deep; the more I give to thee, the more I have, for both are infinite”William Shakespeare, Romeo & Juliet

William Shakespeare, Romeo & Juliet

I love mangroves. So much so that I essentially have a t-shirt to that effect (ok not yet but it’s being ordered). But why is my love so strong? Is it their unique ‘skirt’ roots? Alas, it is not their appearance that entices me – this love runs far deeper than the shallow waters they inhabit. It is because they are mighty in several ways for our planet and the biodiverse species that have long lived symbiotic relationships with them. Arguably they don’t get the cred they deserve, often not making major headlines as they get continuously bumped off by the Amazon rainforest (that’s not to put the Amazon down, it’s brill too, but not as brill which you’ll find when you read on). I should mention that the recent Montreal Biodiversity COP15 (2022) ended with a momentous agreement from parties to increase protection area to 30% globally by 2030 – there’s cred to come for the mangrove we hope! (United Nations, 2022). 

So in this love sonnet to the mangrove, I’d like to unpack more on how they function and what they require, what beneficial aspects (hereon referred to as ecosystem services) they provide to us and the marine/ terrestrial life they support (Bhowmik, 2022). After I’ll cover the problems they are facing and why I leap to their defence in not getting the attention they deserve in conservation and protection efforts. And finally I’ll cover a case study or two on the interventions that are seemingly working and paint a future picture of what good looks like for the mighty mangrove. Will this Shakespearean love story have a happy ending or end in tragedy? Well let’s start at the beginning first, for it is the east, and mangrove is the sun…

But first, what are mangroves?

Mangroves are a type of wetland vegetation with distinctive pronged roots, otherwise called ‘skirts’ that bury deep into the sediment and rock they sit upon. These strong roots allow them to overcome extreme weathers and remain intact where other vegetation may fall. The roots also take in CO2 and store this in the soils they sit (majestically) upon. The older the mangrove, the more CO2 in the soils they grow from. Therefore, ancient mangrove forests are potentially sitting on top of giggatones (GT), estimates putting this at 22.86 GT globally (Czerski, 2022) – that’s not a figure to turn your nose up at! The technical term for this carbon storage is known as ‘sequestration’.

Also, they are specially adapted to thrive in highly saline waters. Fun fact – they can live in waters that are 100 times saltier than other plants can survive (Charles Darwin Research Centre, 2023) and take in water, purify it, and return it back to the environment through the ecosystem cycles they exist within (known as water cycling). They are also usually found in shallower waters as the ocean connects with land, otherwise called ‘wetlands’ (others in this category include marshes, swamps etc.)

Got it, but what makes them ‘mighty’? Mangrove ecosystem services (ES)

We are going to gallop through some of the ES benefits mangroves provide, both directly for humans, as well as indirectly supporting the marine and land ecosystems that, down the line, sustains us too (Charles Darwin Research Station, 2023):

• Carbon sequestration: we’ve covered this one a bit already above. Essentially mangroves are fantastic natural carbon capturers. This is the main reason why they top the rainforests in my humble opinion – they can absorb 5-6 times more 
• Water cycling. Mangroves naturally clean the water as it comes in from the coast, removing pollution and excesses in salinity. Therefore they enable water resources for us as humans as well as to support marine life too. 
• Nutrient cycling. As their leaves turn yellow and decay they drop into the waters beneath and decompose into organic material. This is a key food source for many species, including shrimp, worms, fish and urchins. 
• Critical habit. Countless species call mangroves their homes, nurseries or shelters at some point in their lifecycle. For example, some shark species will lay their young in mangrove forests, enabling them to grow and master their skills before hitting the harsher world of the open deep ocean. Decline in mangrove coverage has meant many species have struggled with these key life stage activities. 
• Extreme weather protectors. Given their deep, strong roots this enables them to act as a barrier against events like tropical cyclones. Cyclones can involve storm surges that include huge waves, high wind speeds and temporarily increased surface levels which cause floods and destruction for animals and humans. Mangrove forests can act as the first natural line of defence, called a ‘soft defence’ as opposed to ‘hard defences’ like a constructed, man-made sea wall.

Ok they are pretty cool, so what’s the issue?

The numbers don’t all agree but according to the latest state of Mangroves Report (Marice 2022) there has been a 22% mangrove loss between 1980-2007. Regardless of the exact figures, we know that these forests are dwindling across the globe, albeit in some areas more than others. Why? This is a sum of two distinct parts; human impact and climate change. See the cheeky Venn diagram below for a quick snapshot of these:

As seen above, there are a huge number of factors caused by the Anthropocene (the human sphere) when it comes to mangrove forest decline, many concerned with overuse; fishing, cooking, wood. Interestingly in a study in Madagascar, Jones (2014) found mangrove recovery was significantly less when forests were positioned nearby villages, and the bigger the village, the less restoration. This obviously means there are some clear things humans can do within our control to help recover mangroves. I’ve no doubt you don’t have time to dive into all of these you busy bee you, so here’s a brief overview of some:

1. Salinity: freshwater ratio change. Oceans are intensely changing, and increased freshwater is one of these variables. Caused by increased ice sheet melting and drastic alterations in global ocean currents, this freshness certainly isn’t something admired by the mangroves who like it salty. 
2. Extreme weather. Climate change is causing more intense events, such as tropical cyclones. These, of course, wreak havoc on forests and, despite being quite hardy vegetation, can only survive so much when it comes to intense winds and powerful storm surges. 
3. Urban coastal development & aquaculture. Both of these essentially act as competitors for the land the mangroves sit upon, and given its humans behind these forcing functions, you know who is going to lose the battle. Our population is growing at an unprecedented rate (almost doubling since 1970s, Bradshaw 2018) so land is becoming more and more precious for infrastructure. In the case of aquaculture, mangrove clearing has taken place on a massive scale in Asian countries and turned over to shrimp farming. Connect these two together and you’ve got a need for more aquaculture to feed that growing human total. Oh mangrove – the slings and arrows of outrageous misfortune.

What can be done to help them?

There are a variety of methods being conducted by scientists, NGOs and investors around the globe in relation to mangrove coverage, however here’s a look at a few of the common approaches and applied them to real life projects in Madagascar and Singapore.

Protection.

Ok, so this one isn’t a radical, sexy method that is the stuff of Shakespeare, but it is perhaps the most practical and popular. Giving mangroves national protected status automatically sets the tone for their significance to that country, establishing the necessary laws in order to enforce any infringements upon such rules. Also, zoning is a common practice within protected areas, such as setting boundaries where there can be some controlled human contact (e.g. fishing, tourism) and areas where these should be left totally untouched (for example organic recovery of mangrove areas). Indeed, in the latter, it has been proven that mangroves destroyed by extreme storms can fully recover within a 10 year period (Bardou, 2021). 

Often through this method there can be many social opportunities, if considered, or serious limitations of success if such opportunities are not.

Enable necessary social developments.

As mentioned, mangroves have a variety of ES that benefit humans, like direct resources of wood, cooking and fishing. These are often intrinsic to the livelihoods of local people. However, if a protected area is implemented, there must be consideration of how such reliance on mangrove resources can be transitioned to alternatives. For example, in Madagascar the mangroves were classified as ‘endangered’ by the FAO in 2007, prompting a boom in protected areas (Felson, 2021). The Tahiry Honko Project involved providing the Vezo villagers with alternative job opportunities in managing 1,200 hectares of protected mangrove forests (Blue Ventures, 2018). There have also been alternate forests built to use for wood and education provided on other aquaculture beyond fish, for example sea cucumber farming (yep, who knew that was a thing!). Without such, it is likely illegal fishing and forest clearing would continue – in order for these projects to be sustainable, so too must the livelihoods of people. I saw the magic of this in real life when I visited a managed Mangrove Forest in the Philippines, Palawan. Local villagers were trained in forest management and eco-tourism, enabling them to have thriving livelihoods and awareness of resources they could and could not take in order to have sustainable mangrove resources.

As an aside…interestingly, Locatelli (2014) comments that such protection and conservation efforts could shift wealth away from the extremely affluent in the West to the developing economies of the East. How? Through biodiversity or net zero offsets, whereby the objectives are to ensure no net biodiversity losses or net zero emissions from processes by supporting initiatives elsewhere – cut down a tree, plant another tree. If only things were so simple, I have previously mentioned in my other blog on the concept of net zero how deeply sceptical I am of this in practice. Offsetting is not only growing in terms of emissions, but in biodiversity too, and studies have found these biodiversity projects are too narrow in proving their ‘net’ ability, focusing only on habitat and area as opposed to more intricate measurements on ecosystem behaviours and species richness (Mashall, 2020)

Reforestation & afforestation.

 To reforest or to afforest? That is the question. Well, it’s probably worth defining these first! Reforestation refers to recovering previously forest covered areas, such as if mangroves had been cleared for urban development or for shrimp farming (a very common reason, seeing as the conditions are right for this sort of aquaculture). Afforestation, however, is generating forest growth that was not there previously, taking advantage of abandoned land for planting. In fact there is a growing opportunity to repurpose abandoned agricultural land, given there are stats to suggest in the EU alone 20 million hectares of agricultural lands are projected to be abandoned between 2015-2030 (Wang, 2023).*Whilst reforestation is a little more straightforward (I say this very broad brush, as soils may be degraded and so require a lot of attention to be fit for our mighty mangrove’s purpose once more), afforestation can be more complex. In order to avoid being intrusive to the local ecosystems, ‘rewilding’ aspects should be considered; thinking through the ecological impacts of such tree species being introduced and turning these into biodiversity opportunities, not issues.

In the case of Singapore with its piddly 10% mangrove areas remaining, it saw reforestation as key mainly for the ES aspect of protection against flooding and extreme weather (Tam, 2021). The island of Palau Tekong had previously harboured mangroves but had severely declined due to sediment erosion (Tan, 2010). Reforestation projects of planting seedlings were established alongside ecological engineering techniques to protect this land, like artificial walls and engineered sediment.

*there are a variety of reasons for this, mainly economical such as market decline, owner financial troubles or actually because the land itself is no longer as productive as it was (Wang, 2023)

Ecological engineering.

You might wonder what I was on about just now. This can be described as ‘the design of sustainable natural and artificial ecosystems’ (Jorgensen, 2021), therefore there is a heightened intentionality (wow, that’s a word) in creating an environment that best supports the target ecosystems. In the case of mangroves, this could include anything from applying specific planting techniques like spacing and seedling selection, through to introducing a water system that controls the salinity, depth and pollution levels. In the case of Singapore, seedlings were planted using a technique called ‘tubing’, acting as a protective barrier against other competing plants or chemicals. In simpler terms, it is somehow changing the environment for ecological benefit.The results of both Madagascar’s and Singapore’s efforts have been largely positive, with Madagascar gaining almost 5% mangrove coverage overall and, specific to the Tahiry Honko project, having virtually non-existent illegal deforestation (Blue Ventures, 2018). Singapore’s project being classified as ‘successful’ via an independent review in tackling the issue of sediment erosion to stabilise forest growth there through their clever engineering efforts (Tam, 2021). All’s well that ends well eh Shakespeare fans?

Wrapping up…

Ah mangrove, can I compare thee to a summer’s day? Thou art more sequestering and nutrient cycling. The fact they do not get the same attention as rainforests is, to me at least, bewildering considering that they outmatch them in carbon storage, are equally significant when it comes to biodiversity amongst many other ES aspects aaaanndddd are arguably more resilient in the face of climate change stressors. So what does the perfect happy ending look like for our beloved mangrove? Well, we can’t consider that in isolation of social factors because, as we’ve covered, if we were to only look at conservation projects purely from the environmental lens, it would be to the detriment of a successful project. 

So, from my readings and understandings thus far, here’s my top 3 recommendations to secure sustainable futures for mangrove forests:

• Plan conservation/ reforestation/ afforestation efforts smart with climate change in mind. This may also mean applying ecological engineering techniques as ways to bolster mangrove tolerance to changes in their environment, such as supplementing the waters with salt to address the right balance or implementing remote sediment sensors to monitor health and stability. This even extends to choosing the best mangrove seedling species for the environment. Of course, this also means being selective with the constrained resources you have regarding conservation funds and specialised workers. You don’t want to put effort into an area that is likely to have large exposure to detrimental climate change impacts, for instance coastal extreme events. It means saying no just as much as saying yes with this point, as unfortunately you’ll never have endless resources, or time…
• Define and align stakeholder motivations across scales. In order for any project to really hit the ground running, you have to define the ‘why’ and this varies depending on where you sit and what your interests are. A local mangrove fisherman wants to ensure they/she/he will continue to have a livelihood that supports them, a government official wants to ensure the nation functions effectively, an NGO worker wants to ensure global targets and protocols are upheld. The difficulty but importance is in aligning these, understanding where there could be trade offs and, through conscious design and conversation involving all, turn these trade offs into opportunities where possible. Achieve this and you integrate the environmental with the social, driving successful outcomes.
• Give them national protective status, zones and resources to enforce infringement. Essentially this means giving mangroves and their ecosystems rights to be left alone or used sustainably. In the case of Madagascar it made clear to all nationals the importance these forests have, not just internationally for conquering climate change but also in order for Madagascar to continue reaping their ES benefits. The legal and governance aspects that wrap around such projects are crucial because we know transitions are hard, so governments must provide the hard measures (penalties for infringement) as well as the sort measures (education, initial financial support etc.) to enable local people to move to greater sustainable usage.

Now of course I’d like to see more projects for mangrove conservation too, given the rapid decline felt globally. But I’d like to think this is on an upwards trajectory as the Montreal global targets come into fruition. So my ode to the mangrove ends with hope: not that they will come to a tragic end by poison or dagger like Juliet or King Duncan (gotta love a bit of Macbeth) but of restoration. With human help instead of hinderance, their bolstered ability to weather the storms of human-induced climate change can actually help tackle it. Because, as Shakespeare put it in the opening quote – ‘the more I give to thee, the more I have’. In other words, if we scratch their biodiverse backs, they’ll scratch ours.

References:

• Czerski H., ‘Coral Reefs – The Rainforests of the Sea’, Bertarelli Foundation (2021).
• Charles Darwin Research Centre, Santa Cruz Galapagos Islands, Last accessed May 2023. 
• BBC World series, ‘where have all the mangroves gone?’ (2022)
• Mashall, E., B.A. Wintle, D. Southwell and H. Kujala ‘What are we measuring? A review of metrics used to describe biodiversity in offsets exchanges’, Biological Conservation 241 2020. 
• Jorgensen, S.E., ‘Ecological Engineering Overview’, Ecology Center (2023). Available at: https://www.ecologycenter.us/ecological-engineering-2/ecological-engineering-overview.html.
• Locatelli T., Binet, T., Gitundu Kairo, J., King, L., Madden, S., Patenaude, G., Upton, C., Huxham, M., ‘Turning the Tide: How Blue Carbon and Payments for Ecosystem Services (PES) Might Help Save Mangrove Forests’, The Royal Swedish Academy of Sciences, 2014 (43), 981-995. 
• Blue Ventures, ‘Community Mangrove Carbon Project, Southwest Madagascar’, 2018 Annual Report, Blue Ventures (2020). Available at: https://www.planvivo.org/tahiry-honko.
• Bhowmik, A.K., Padmanaban, R., Cabral, P., Romeiras, M.M., ‘Global Mangrove Deforestation and Its Interacting Social-Ecological Drivers: A Systematic Review and Synthesis’, Sustainability (2022) 14(8).
• Felson, A.J., Ellison, A., Friess, D.A., ‘Mangrove Rehabilitation and Restoration as Experimental Adaptive Management’, Frontiers in marine science, (2020).
• Maricé, L.,  Spalding, M.D., ‘The State of the World’s Mangroves Report 2022’, Global Mangrove Alliance (2022). Available at: https://icriforum.org/the-state-of-the-worlds-mangroves-2022-report/.
• Tam, S., ‘The Convergence of Mangrove Rehabilitation Projects and the Agenda for Urban Development in Singapore’, Environmental Policy Group Wageningen University (2021). 8Available at: https://edepot.wur.nl/557776.
• Tan, R., ‘Saving Singapore’s last best mangroves at Pulau Tekong’, Wildshores Blogspot (2010). Available at: https://wildshores.blogspot.com/2010/05/saving-singapores-last-best-mangroves.html#.ZAOcPz1ME1K.
• United Nations, ‘COP15 ends with landmark biodiversity agreement’, UNEP Environment programme (2022). Available at: https://www.unep.org/news-and-stories/story/cop15-ends-landmark-biodiversity-agreement.
• Wang, L., Svenning, J.C., Pedersen, P.B.M., ‘Rewilding abandoned farmland has greater sustainability benefits than afforestation’, Nature 2, 5 (2023). 
• Starr D., ‘Where have all the mangroves gone?’, BBC World (2022).
• Jansz, S., ‘Achieving a climate resilient future in 2050 through biodiversity: coastal ecosystem pathways’, University of London (2023).
• Jones T.G., Ratsimba, H.R., Ravaoarinorotsihoarana, L., Cripps, G., Bey, A., ‘Ecological Variability and Carbon Stock Estimates of Mangrove Ecosystems in Northwestern Madagascar’, Forests (2014).
• Bradshaw, C.J., P.R. Ehrlich, A. Beattie, G. Ceballos, E. Crist, J.  Diamond, R. Dirzo, A.H. Ehrlich, J. Harte, M.E. Harte and G. Pyke ‘Underestimating the challenges of avoiding a ghastly future’, Frontiers in Conservation Science 1 2021, p.9.