Salinity who do not comply can thwart breeding and hamper growth. Mussels, clams and oysters blood are the types of shellfish that live in estuaries. Variations of natural salinity estuaries in Indonesia ranged between 15-32%. Results of research on mussels indicates that the salinity of 15% of the shellfish can cause death. The success of shellfish seed blood to stick to the collector depends on salinity. At salinity of 18%, higher sticking success.
Oysters can live in waters with lower salinity than the salinity of mussels and clams blood. Grouper and beronang can live in estuaries and reefs. Snapper live in coastal waters and estuaries. Seaweeds live in the coral. In general, natural salinity waters of the coral reefs in Indonesia 31%.
a) Distribution of Salinity Vertical
Vertical distribution of salinity are closely related to the vertical distribution of temperature and density. In general, sea level has a higher salinity than the layers deeper. This is caused by the effect of temperature distribution on the stability of water greater than the effect of salinity distribution. On the surface of the sea water has a lower salinity than the layers underneath, this is because the movement of the wind, and rainfall could also affect the salinity difference is.
In the troposphere layer, salinity has decreased up to a depth of 500 meters (34.3 to 33.9 ‰). Then there was an increase in salinity again to a depth of 1600-2000 meters (34.8 to 34.9 ‰). The distribution of salinity in stratospherelebih clear layer to the horizontal direction.
Figure 7. The vertical salinity stratification based on the depth of the waters
b) Distribution of Salinity Horizontal
Salinity in the Atlantic, Pacific and Indian Oceans are very dependent on latitude. Minimum salinity found in the equatorial region and maximum salinity in the area 20ºLU and 20ºLS, then salinity decreases again toward the poles. The low salinity in the equatorial region due to the high rainfall, plus many rivers emptying into the sea. Whereas in subtropical areas mainly dry climates where evaporation is higher than precipitation, salinity can reach 45%. It can be found in the Red Sea and a lagoon-lagoon in Texas USA.
Figure 8. Distribution of salinity horizontally