All you need to know about Mangroves

Mangroves are survivors as they grow in such conditions, which would kill most plants. The mangrove ecosystem also supports an incredible diversity of creatures. And, as scientists are discovering, mangrove swamps are extremely important to our own well-being and to the health of the planet. What are Mangroves? A mangrove is a woody tree or […]

Mangroves are survivors as they grow in such conditions, which would kill most plants. The mangrove ecosystem also supports an incredible diversity of creatures. And, as scientists are discovering, mangrove swamps are extremely important to our own well-being and to the health of the planet.

What are Mangroves?

A mangrove is a woody tree or shrub that lives along sheltered coastlines within the tropic or subtropic latitudes. In fact, the various species of mangroves aren’t necessarily closely related to one another, but they do share the unique capability of growing within reach of the tides in salty soil. Some mangrove species live so close to the shoreline that they are flooded with salt water every day as the tide comes in and submerges their roots. All mangroves have evolved special adaptations that enable them to live in salty, oxygen-poor soil.

There are roughly 54 true species of mangrove belonging to 16 different families.

Location

Mangroves grow in sheltered tropical and subtropical coastal areas across the globe. A major restriction for where mangroves can live is temperature. The cooler temperatures of northern temperate regions prove too much for the mangroves. However, rising temperatures and sea level due to climate change are allowing mangroves to expand their ranges farther away from the equator and encroach on temperate wetlands, like salt marshes.

On tropical islands, such as Hawaii and Tahiti, mangroves are not native and are considered invasive species.

The salty soils of the intertidal pose an inhospitable barrier for most woody plants, but the mangrove is uniquely adapted for these conditions. These adaptations are so successful that some mangroves are able to grow in soils that reach salinities up to 75 parts per thousand (ppt) about two times the salinity of ocean water.

The soil where mangroves are rooted severely lacks in oxygen. The environment allowed for the evolution of a variety of special structures that help the underground roots gain access to air, even when submerged by the tide.

Reproduction

Mangrove offspring begin to grow while still attached to their parent. This type of plant reproduction is called vivipary. After mangrove flowers are pollinated the plants produce seeds that immediately begin to germinate into seedlings. The little seedlings, called propagules, then fall off the tree, and can be swept away by the ocean current. Depending upon the species, propagules will float for a number of days before becoming waterlogged and sinking to the muddy bottom, where they lodge in the soil.

Diversity

Mangrove trees can be distantly related and are grouped together for their shared characteristics rather than true genetic ties. Some individuals will grow to be no more than stunted shrubs while others will grow to be up to 131 feet tall.

A mangrove forest can be categorised as mangrove fringe, overwash forest, riverine mangrove, basin mangrove, dwarf or scrub forests.

Ecosystems

Mangroves are among the most productive and biologically complex ecosystems on Earth. They cover between roughly 138,000 and 200,000 sq km globally.

The Sundarbans Forest, a UNESCO World Heritage site at the mouth of the Ganges, Brahmaputra, and Megha Rivers in the Bay of Bengal fronting India and Bangladesh, is a network of muddy islands and waterways that extends roughly 10,000 sq km.

Mangrove forests are important feeding grounds for thousands of species and support a diverse food web. Some of the organisms include crabs, monkeys,underwater sponges, snails, worms, anemones, barnacles, oysters, shrimp, fish, ants, spiders, moths, termites, scorpions, snakes, lizards, frogs, brown pelicans and even the Royal Bengal Tiger.

Our Protectors

Mangroves also impact many aspects of people’s lives. Mangroves form dense barriers against storms and tsunamis, saving lives and property. They provide us with food, medicines, fiber and wood. They stabilise shores by trapping sediments and building land. They improve water quality by filtering runoff and polluted waters. They protect the climate by absorbing carbon dioxide. The world’s mangrove forests provide human communities with many billions of dollars’ worth of services.