In order to deal with the high salinity, anoxic and shallow soil in mangrove, species had developed several adaptations.

Plant adaptations

(A) High salinity

Salinity directly affects the water potential of plant cells. Medium with high salinity will draw water out from the plant cells. Disturbance of water potential may result in non-functioning of enzymes, wilting, or even make photosynthesis not possible. Therefore, mangrove plant species have one or more than one, of the following characteristics:

Aegiceras corniculatum

Capable of secreting excess salts - Secretion of salts occurs through some special salt glands. These glands are usually found on leaves. Often, white flecks of salt can be seen on the leaves. One of the exmples which can secret salts is Aegiceras corniculatum.

Capable of excluding salts - This is done by a physical process called ultrafiltration. The root cell membranes act as a physical barrier. Only small molecules, such as water, can enter the root through the membrane. While large molecules, such as salt ions, are not small enough to go through the membrace. Thus the majority of salt ions can be excluded by this way.

Capable of storing salts - Mangrove plant species usually store salts in their leaves. When leaf fall occurs, the salts in the leaves are also taken away.

(B) Anoxic soil

Anoxic soil means the soil with only little oxygen. As oxygen is required during photosynthesis, so mangrove plants usually have special methods to obtain oxygen.

Avicennia

Possession of pneumatophores - Pneumatophores are special types of aerial roots, which grow upwards from the main root system above the mud, to absorb oxygen from the air at low tide. The photo shown on right is from a species called Avicennia. Besides growing from the main root system, some mangrove species have the aerial roots grown from the trunk and lower branches. These aerial roots enable mangrove plants to obtain enough oxygen for photosynthesis, metabolic reactions, etc.