week 5- mangrove habitats

Tropical inshore communities dominated by species of trees and shrubs that grow in permanently salty water

Mangrove species are terrestrial plants that have colonized the fringes of the sea

Mangroves buffer tropical shorelines from erosion and filter runoff

in the tropics

Mangrove roots grow in a hostile soil environment Soil is oxygen deficient and often has a higher salinity than open ocean due to evaporation

In the absence of oxygen, anoxic reactions take place sequentially as organic material is broken down

• Shallow rooting system that is wide-spread or perpendicular to the trunk • Elongation in Rhizophora can be as much as 9 mm a day • There are several species-specific adaptations to cope with the oxygen-deficient soil • Most of these consist of aerial roots that can represent up to 24% of above ground biomass

Aerial roots of Rhizophora are often known as stilt roots Branching increases anchorage points also securing the plant against wave action The height of pneumatophores is a response to tidal cycles of water submergance

• To counteract the uptake of salt water, root systems build negative hydrostatic pressure by transpiring salts at the leaves through salt glands • Leaves have hairs to precipitate the droplets of salty water