Upper and Splash Zone

The upper and splash zones are frequently exposed to the air.  Because of this, temperature and salinity fluctuations are high and desiccation or drying out of organisms is common. Isolated pools can warm up to extremely high temperatures causing seawater to evaporate and the salinity to increase dramatically. When it rains, the same pools can fill up with freshwater and salinity will decrease accordingly. In addition, both land and sea predators use this zone for feeding. 

 

These factors result in a very high stress environment.  This is a hard place to live!!!!! Most organisms here have some type of adaptation to cope with the stress in these zones.  The most common is for shellfish to clamp their shells together (or to a rock) during low tide to limit their exposure time to the air.  The result is less exposure to temperature and salinity fluctuations, and much less desiccation.  Because of the high stress environment, there is normally an abundant space as few species can survive here. These factors means that the species diversity is low (few species). 

 

Temp/Salinity fluctuations: HIGH   Stress level: HIGH  Limiting factor: Ability to survive harsh PHYSICAL conditions

 

Index species: Periwinkle snails, Fingernail limpets, Buckshot barnacles

 

Typical Upper and Splash Zone setting.  This day had what appeared to be a strange green (algae?) bloom as you can see on the rocks.  Normally the space taken up by the green portions of this picture would be mostly vacant of organisms.