The Addicted Photographer
All About Water
Panasonic DMC-TZ18 (underwater housing)
Photo taken in Carriacou/Caribbean
Mangroves are various kinds of trees up to medium height and shrubs that grow in saline coastal sediment habitats in the tropics and subtropics – mainly between latitudes 25° N and 25° S.
Red mangroves exclude salt by having significantly impermeable roots which are highly suberised, acting as an ultrafiltration mechanism to exclude sodium salts from the rest of the plant. Analysis of water inside mangroves has shown 90% to 97% of salt has been excluded at the roots. It has been frequently stated that salt which does accumulate in the shoot, concentrates in old leaves which the plant then sheds, a concept that has become known as the “sacrificial leaf.” However, recent research suggests that the older, yellowing leaves have no more measurable salt content than the other greener leaves. Red mangroves can also store salt in cell vacuoles. As seen in the picture on the right, white (or grey) mangroves can secrete salts directly; they have two salt glands at each leaf base (co-relating with their name—they are covered in white salt crystals).