Substrate waters is the basis waters where algae can grow and develop properly. Deployment of sea algae and density in a body of water depends on the type of substrate, seasons and species composition. According to Mubarak and Wahyuni (1981) the types of substrates that can be covered by marine algae is sand, mud and rubble. The best type of substrate for the growth of marine algae is a mixture of sand, rocks and rubble.
On soft substrates such as sand waters and mud, will be found many kinds of marine algae Halimeda sp, Caulerpa sp, Gracillaria sp. While bottom waters are bersubstrat hard as live coral, rocks and rubble will encounter many types of marine algae Sargassum sp, sp Turbinaria, Ulva sp, and Entermorpha sp. Nontji (1993) stated that at least marine algae found in waters with sand or muddy base, due to the limited hard objects are sturdy enough to place attachment.
Chemical composition of the substrate does not affect the life of marine algae, just as the attachment of marine algae at the bottom waters. Marine algae Eucheuma sp is the most excellent growth at the base of the rocky waters.
Dissolved oxygen is very important because it is needed by aquatic organisms. Dissolved oxygen is generally encountered in the surface layer, therefore the oxygen gas from the air nearby conduct dissolution (diffusion) into the water. Phytoplankton also helps increase the amount of dissolved oksigan levels in the surface layer at a time when daytime. This addition is caused by the release of oxygen gas as a result of photosynthesis.
The solubility of oxygen in the sea is very important in influencing the chemical equilibrium of sea water and also in the life of the organism. Oxygen is needed by animals and water plants, including bacteria for respiration. DO quality standard for the seaweed is more than 5 mg / l (Sulistijo and Atmadja, 1996), this means that if the dissolved oxygen in waters up to 5 mg / l, the metabolism of seaweed can run optimally. Buesa (1977) in Iksan (2005) states that the daily oxygen changes may occur in the sea and can be significantly affected benthic algae production. Fortunately usually always enough oxygen for the metabolism of algae (Chapman, 1962 in Iksan, 2005).