Plants are expected to consist of roots, stems and leaves. It’s usually assumed that dirt is somehow involved. Mangrove plants, however, are an exception. Mangroves are groups of trees and shrubs that grow in saline or brackish water in inter-tidal areas between land and the sea in subtropical and tropical regions. There are 69 “true” mangrove species that are adapted to saline water and which don’t grow near land . Mangroves look like trees that have been yanked out of water. Their roots sit above the waterline. Growing above and in water provides mangrove forests with one of the most diverse ecosystems in the world.
So how does a mangrove plant grow in water?
Firstly, mangroves have adaptations that enable them to live in a coastal saline environment. Some adaptations are exposed breathing roots, salt-excreting leaves, and viviparous water-dispersed propagules.
1. Exposed breathing roots.
Most mangrove species’ roots don’t penetrate the mud underwater at a great depth. They spread out and create lateral roots that help anchor and stabilize the roots. There are four main types of roots in mangroves: knee roots (these look like knobby knees sticking out of the water), stilt roots, buttress roots and roots that grow upwards called pneumatophores, or pencil roots.
Pneumatophore roots and the airbreathing, raised bumps on the bark of the tree called lenticels are the primary sites of gas exchange.  Another important task carried out by the roots is the filtration of salt from the water. The roots filter out a full 90 percent of the salt, leaving just 10% of the salt to be filtered by the leaves. 
Mangrove leaves have a thick waxy layer (cuticle) which prevents water loss through evaporation and makes the leaves feel leathery. Some species of mangroves have leaves with hairs on them which reduce the effects of wind and sunlight . This in turn reduces water loss through the stromata (the tiny openings where gases enter and exit during photosynthesis).
Some species excrete salt through special cells in their leaves. Although these leaves may be covered in salt crystals it’s not recommended to taste them. In another type of salt excretion the salt gets concentrated in older leaves or the bark of the tree. When the leaves fall or the bark sheds, the salt goes with them. 
3. Viviparous water-dispersed propagules.
Yes, that is a mouthful. But let’s break it down because this is probably one of the coolest and most unexpected aspects of mangroves.
Vivipary is when something is born through live birth. (e.g. Mammals)
Propagules are vegetative structures that can become detached from a plant and give rise to a new plant. (e.g. A bud, sucker, or spore.) 
Salty water is not the most ideal environment to grow a plant. It usually has little to no oxygen which makes it difficult for the conventional plant seed to establish itself and grow. But mangroves aren’t conventional. Instead, the seeds germinate and develop into seedlings while still attached to the parent tree. These seedlings are called propagules and they continue to photosynthesize while they float in the water. The parent tree supplies water and nutrients until they detach [2 & 5]. It’s like a far less complex version of an umbilical cord.
But beyond their evolutionary adaptations to living in salt water, mangroves provide essential ecosystem services. Ecosystem services are the direct and indirect contributions of ecosystems to human survival and quality of life . These ecosystem services by mangroves equate to 1.6 billion dollars US annually .
Habitat and Refuges
Mangrove roots create refuges and habitats for algae, amphibians, bacteria, crustaceans, fungus, fish, and mammals. Essentially, studies have shown that mangroves are critically important in creating habitats for many species along with nurseries for fish which are often caught by offshore fisheries [1,7, 8].
Despite being known for being unique underwater ecosystems, the mangrove canopy also functions as a refuge for birds and mammals. A recent study has found that 464 different terrestrial mammals use mangroves for their habitat, which was far higher than previously thought .
Produce oxygen and water purifiers!
Mangroves also have high rates of productivity. They produce oxygen through photosynthesis and beyond that, their roots filter water of nitrates and phosphates that rivers and streams carry to the sea from industrial areas . Not only do they function to produce organic materials in their environment, but they also function to clean up the environment as well.
Mangroves provide coastal protection by being a bio-shield . The roots of mangroves slow the movement of tidal waters, and build up the muddy bottom. They also reduce erosion from storm surges, currents, and waves. By doing this they act as a buffer for the coastline. Most importantly, multiple findings have shown mangrove forests have reduced the impact of tsunamis and cyclones [11-14].
Supports local lifestyle and tourism
Mangrove forests provide many resources which coastal people depend on for their survival and livelihood. Mangrove trees provide fuel, medicines, tannins, and wood for building houses and boats . Tourism is a new and emerging aspect of mangrove ecosystems. Since these ecosystems are so unique, tourists are keen to visit sanctuaries to go snorkeling or diving. This in turn allows for local and sustainable eco-tourism.
Mangroves are highly adapted plants that offer tons of ecosystem services. However, close to half of the world’s mangroves have been lost in the last 50 years because of pollution, habitat destruction and climate change. The world’s most diverse mangrove ecosystems are located in the Indo-Malay Philippine Archipelago which has seen the greatest loss of mangrove forest .
The primary reason for the destruction of mangroves in this region is the clearing of forest land in order to create shrimp and fish ponds for farming.  If the practice of forest clearing continues in combination with climate change, then a resulting 1 meter increase in sea level rise will displace an estimated 24 million people from Bangladesh, India, Indonesia, Cambodia, Vietnam, and the Philippines .
But it’s not all bad news. The International Union for the Conservation of Nature has elevated eleven species of mangroves to endangered status which provides them with more legal protection . Additionally, more mangrove forests are becoming designated as sanctuaries and conservation areas . Restoration projects have been completed and have shown success . Nevertheless, further research and conservation efforts must be made to ensure that mangroves and their associated wildlife don’t become extinct.
Sabah Wetlands Centre
If visiting Kota Kinabalu, Malaysia, head to the Sabah Wetlands Centre (formerly known as the Kota Kinabalu Bird Sanctuary) to see some mangroves and wildlife. The wetlands have 24 hectares of mangrove forest with a 1.5-kilometer boardwalk that’s perfect for spotting up to 80 different species of birds including egrets and kingfishers. The best time to go is at dusk (but take insect repellent!), and if you look at the mud flats when the tide is low then armies of blue crabs will be present along with mud skippers. This is also the time that the birds will be active. The entrance fee is 15 Ringgit for an adult and comes with a wildlife guide .
However, one thing to note is that there is garbage that flows into the reserve from the city itself. The occasional sighting of garbage detracts from the whole experience. Since this sanctuary is operated by a non-profit they have limited funds to work with, making clean up and maintenance very difficult. Nonetheless, credit should be given to the Sabah Wetlands Conservation Society for working hard to conserve the wetlands from development.
It’s possible that the tide may change. It’s possible that through the efforts of conservation areas such as the Wetlands Centre mangrove ecosystems will get the attention that they deserve. For the sake of the organisms that rely on them, let’s hope that they do.
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 Merriam-Webster. (2017). Viviparous. Retrieved from: https://www.merriam-webster.com/dictionary/viviparous
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If any information is incorrect or needs to be updated, please let me know. Science is about moving forward with the most up to date information!