YOU may, in recent times, have heard quite a bit about mangroves and their importance to Jamaica – particularly when the island is experiencing stormy weather. But what are they exactly and precisely how do they function to protect our habitat? Some insight follows.

The what

Mangroves are salt-tolerant (halophytic) dicot trees that live in areas saturated with salt water at least part of the time. They may be found throughout the tropics – Jamaica included – and subtropics wherever coasts are gently sloping and temperatures average 240ºC (800ºF).

There are nearly one million hectares of mangrove left in the insular Caribbean basin, which is representative of more than five per cent of the mangroves left in the world.

There are 50 species of mangrove worldwide. However, most Caribbean mangrove stands are dominated by:

. the Red Mangrove-Rhizophora mangle;

. thee Black Mangrove-Avicennia germinans;

. the White Mangrove-Laguncularia racemosa; and

. the buttonwood Mangrove-Conocarpus erect us.

Ensuring survival

Mangroves have several adaptations (changes in structure and function that allow them to live under high salt conditions.

1. Some mangroves (the black and white mangrove) have salt pores and glands on their leaves, which can excrete salt that is taken up by the roots and trunk.

2. Some (the prop roots of the Red mangrove) have roots and trunks that are impermeable to salt.

3. All the mangroves display a unique reproductive mechanism known as vivparity. Instead of releasing seeds that would soon get soaked with salt and die, the seeds of the mangroves germinate while still attached to the tree.

The fully developed seedlings (propagules) are then dropped from the trees and plunge into the mud or water below. Some root where they fall, while others are washed away by waves and current.

More next week