Since 2015 after 5 years of development and multiple student theses aimed at improving the ecological health of the on campus West Lake, the Student Union of Asian Institute of Technology (AIT), supported by partner Thai Pipe Industry Co., recently launched a unique Freshwater Mangrove Museum. The real breakthrough for the newest campus landmark, however, sprang from the academic work of PhD candidate Ms. Arlene Gonsalez guided by her supervisor Dr. Oleg Shipin, a faculty member of the Environmental Engineering and Management Program. The pair has developed an innovative 3R Biotechnology based on freshwater mangrove trees and associates.

Mangroves, ‘well known’ as obligate salt-dependent marine coast trees, in fact can perfectly grow in fresh water in the areas thousand kilometers inland. Inspiration for mangrove planting in fresh water to some extent came from a recent tradition.  The Thai Royal Family was for decades planting certain number of freshwater mangroves for decoration in their Royal estates (Bang Pa In Palace park, Rama VI Phayathai Palace park, etc.). Following up on the Royal example, common Thai citizens were also planting limited number of freshwater mangroves in their personal ornamental gardens. In turn, encouraged by unique properties of mangroves, AIT has been a global frontrunner for creating a novel urban ecosystem on campus to show the multiple ecological benefits that freshwater mangroves (3R biotechnology) can offer cities across the world.The 3R biotechnology advances development by introducing know-hows, which dramatically increase number of the beneficial eco-services. Why mangroves out of many other kinds of trees? They have: (a) the highest rates of metabolism (for anti-microbial chemicals production, and for waste nutrient recycling), (b) highest carbon sequestration (up to 8 times higher than land trees with regards to C storage critically important for climate change mitigation), (c) as an ecosystem they ensure high biodiversity which we lost across the globe, particularly in cities.

The 3R Biotechnology comprises two parts: ‘Hardware’ and ‘Software’. The Hardware part consists of the following components:

• Wetland water (an urban water body ranging from lake, river and pond to canal, marshland and swamp) constituting the Blue component
• Macroflora (diverse mangrove trees; other emergent, submerged, and floating macrophytes) constituting the Green component
• Macrofauna (diverse arthropods: mollusks; crabs, insects; fish; birds, etc) constituting the Green component
• Sediment and soil constituting the Brown component
• Microflora (microorganisms: from Archaea, Bacteria to microalgae, Protozoa and Metazoa (rotifers, etc) constituting the Green component
• Wastewater distribution PVC pipe outlets
• Slow water circulation system
• Near-water green walls (wall creepers, strings/lines, trellis, functional structures, such as pump stations, etc).

The Software part involves the processes in which these hardware components are involved and interact with each other. The processes include:

• Transformation of waste nutrient wastes (C, N, P) into environmentally inert gas forms (N₂, CO₂, and CH₄)
• Sequestration of carbon and capture of other waste nutrients by plants (N, P waste recycling)
• Improved and enhanced ecological trophic chain (increasing abundance of biological groups without compromising their biodiversity quality).

The eco-services/benefits comprise for the 3R freshwater mangroves biotechnology (a) recycling waste nutrients and (b) pollution mitigation, (c) storage of carbon to fight climate change, (d) production of urban food, (e) increasing biodiversity, (f) beautifying the site, (g) noise reduction, and many others.

No botanical garden in the world boasts such a diversity of freshwater mangrove trees and associates, with 30-plus species found at AIT. It is being gradually built up to serve as a Living Biodiversity Gene Bank or a collection of Thailand’s mangrove biodiversity. The 3R Biotechnology, essentially a Water Tree Biotechnology, makes West Lake healthier, and is a showcase for today’s tropical urban world inhabited by at least 1 billion people.

An unusual but important feature became apparent due the COVID-19 situation: Mangroves, as normally highly stressed trees, are known to produce antiviral substances and exude them into the air and water. This purifies the environment and may offer protection to urban dwellers. The Medicinal Garden within the Museum produces medicines and agricultural plants, which are not just food – but also boost human immunity against viral infections. This is important for the COVID pandemic ushered in a New, ‘Viral Era’ of Humanity when viral infections will have unprecedented impact on the society. No single measure (including vaccination) can fully mitigate the impact. Notably, the biotechnology offers low cost response to the issue of airborne transmission of viruses and other microbes, a major concern for WHO. We live in times when coronavirus is bound to be a household threat as much as influenza virus, with apparently newer problematic viruses yet to come. In these times urban tree greening, both on land and in water, is becoming a major necessity due to viral threats which humanity experiences. Why? The point is that the trees are known to produce phytoncides, volatile organic compounds, which they exude into the air to serve a communication between trees of the same genus.

The phytoncides were shown to boost human immune system, our inborn Anti-Viral defense. Specifically, they increase human Natural Killer Cell activity in blood. They also decrease viral and bacterial viability in the air as tropical (and other forests), show lower viral and bacterial counts in the ambient air. The phytoncide research was done in Japan, Korea, USA (Florida), Canada, Europe (Denmark, Lithuania, UK), China and Singapore. Surprisingly, all this is not as widely known as it deserves to be, probably due to our relaxed attitude to airborne pathogens (1-5).

Mangroves are biochemically unique trees that produce wide array of natural products with immense medicinal potential (6-8). Since the trees grow under environmental stress (low oxygen in water, and varying salinity), evolutionarily they regulate a number of novel pathways to biosynthesize secondary metabolites of medicinal properties through their  highest rates of metabolism. Compounds of several mangrove species have been used as drugs in traditional medicine, as well as pesticides. These trees have a proven activity against human, plant and animal pathogens, which include proven broad spectrum antivirals (HIV, and numerous other viruses) and anti-bacterials (against Staphylococcus, multidrug-resistant Salmonella, etc).  Secondary metabolites (incl. phytoncides and other anti-virals) produced by leaves, bark and roots of mangrove trees, act in, presumably, two-fold manner. They exert (i) inhibiting or killing impact on air-borne pathogens through phytoncides exuded into the air and (ii) impact on water-borne pathogens through secondary metabolites exuded into the water environment. Phytoncides also boost the human immune system if humans breathe the air rich in phytoncides. The phenomenon of trees purifying the ambient air and water is called ‘Phytosanitation’.

Typically, freshwater wetland environments (canals, ponds, lakes, etc) in cities are more available for tree planting than already overused terrestrial areas. Hence these can be more effectively used by mangrove trees, as one mangrove tree is known to be equivalent to up to 8 conventional land trees. Mangroves (inland-freshwater and coastal-marine) are important to promote wherever possible, particularly in cities, as they are a major tool in Biodiversity Loss and Climate Change mitigation. Majority of tropical and subtropical cities are freshwater environments. Overall, taking into account a) Climate Change (Carbon Storage through C sinks), b) Biodiversity loss and c)‘the Viral Era’ in cities, now and in future, one can be assumed that the more trees (particularly, mangroves) we bring to cities the more effective is our environmental defense against these main global environmental threats.

References

1. Li et al., 2006. Phytoncides (wood essential oils) induce human natural killer cell activity. (Journal of) Immunopharmacology and Immunotoxicology, 28:319.
2. Tsunetsugu, Y.; Park, B.; Ishii, H.; Hirano, H.; Kagawa, T.; Miyazaki, Y. 2007. Physiological effects of Shinrin-yoku (taking in the atmosphere of the forest) in an old-growth broadleaf forest in Yamagata Prefecture, Japan. J. Physiol. Anthropol., 26, 135–142.
3. Li, Q.; Morimoto, K.; Kobayashi, M.; Inagaki, H.; Katsumata, M.; Hirata, Y.; Hirata, K.; Suzuki, H.; Li, Y.J.; Wakayama, Y.; et al. 2008. Visiting a forest, but not a city, increases human natural killer activity and expression of anti-cancer proteins. Int. J. Immunopathol. Pharmacol., 21, 117–127. 
4. Hansen, M.M.; Jones, R.; Tocchini, K. Shinrin-Yoku (Forest Bathing) and Nature Therapy: A State-of-the-Art Review. 2017. Int. J. Environ. Res. Public Health 14, 851.
5.“Urban Forest Therapy in Singapore. 2018 Report, National Parks Board, Singapore” (www.nparks.gov.sg//media/cuge/ebook/citygreen/cg16/cg16_01.pdf)
6. Premanathan M., R. Arakaki, H. Izumi, K. Kathiresan, M. Nakano, N. Yamamoto, H. Nakashima. 1999. Antiviral properties of a mangrove plant, Rhizophora apiculata Blume, against Human Immunodeficiency Virus. Antiviral Research, 44, 113–122.
7. Sahoo G., N. Mulla, Z. Ansari and C. Mohandass. 2012. Antibacterial activity of mangrove leaf extracts against human pathogens. Indian Journal of Pharmaceutical Sciences.
8. Patra J. K. and Y. K. Mohanta. 2014. Antimicrobial Compounds from Mangrove Plants: A Pharmaceutical Prospective. Review. Chinese Journal of Integrated Traditional and Western Medicine, 20 (4), 311-320.