Generally, the environment in mangroves is highly different from that of other forests, especially soil in mangroves which is abundant with nutrients from the coastal erosion, rivers and the organic matters that are derived from the decomposition process of the leaves, phytoplankton and algae in mangroves. The salinity of water in mangrove is quite low and varied by tides and amount of freshwater from the rivers and channels. Animals living in the mangroves are influenced by the environmental conditions that are different from terrestrial forests, especially, various benthic organisms which inhabit on the ground or in the mud as well as in the water column. These benthic animals such as shells, crabs, shrimps, worms, flat worms, polycheates, etc., have to adapt themselves to the changing environments that affect on their survivals like water loss, high temperature, low oxygen environment and salinity change. A high biodiversity of mangrove communities are resulted from a composition of various organisms that are able to adapt to survive in this environment, serving as nursery grounds and habitats for many important economic species. The environmental factors which play an important role for their survivals are the geography that mangroves which are located in coastal muddy flat with regular tidal inundation. The important environmental factors include:
Climates including light, temperature, rain, wind; most of the mangroves are only found in tropical zone where the tropical climate is suitable for their growth.
Tides are the main factor influencing the zones of mangrove plants or aquatic animals. Tidal ranges influence on the physical characteristics of plant structures, especially, the aeration root which are big, above the ground. The height of this root is resulted from on the tidal range. The more tidal ranges are wider, the higher roots are developed.
Waves and currents help blow the seeds of the mangroves into other habitats, distribute nutrients to the sea that benefit to other aquatic life and coastal aquacultures. Besides, waves and currents are an important factor for coastal sedimentation process.
Salinity of water and soil is significant to the distribution of plants and aquatic animals in the mangroves. A different salinity causes different distributions of plants and animals.
The dissolved oxygen is important to plants and animals; it also controls the types and growth of plants and distribution of aquatic organisms. Furthermore, The rate of decomposition is also affected by the amount of dissolved oxygen.
Mangrove soil is resulted from the deposition process of sediments flowing with water from various sources as well as the decomposition of the organic matter. Soil is important to the growth and distribution of plant and animal in mangroves, for examples, The Rhizophora mucronata is well developed in muddy substrate, while the sandy muddy substrate is suit for the Avicennia marina and Bruguiera gymnorrhiza to grow.
Nutrients, that is vital for the survival of organisms in the mangroves, are derived from both outside and inside the mangroves, that are, rain, rivers, sediments, sea, and the decomposition of organic matter in the mangroves from phytoplankton, diatoms, bacteria, algae, plants, dead animals, etc.