The ability to maintain metabolic and physiological functions in response to variations in the environment is called enantiostasis. It is applicable to any organisms living in estuarine ecosystems, especially mangroves.
All organisms living in an estuary experience large changes in salt concentration in their environment over a relatively short time span, with the tidal movement and mixing of fresh and salt water. Organisms that must tolerate wide fluctuations of salinity are said to be euryhaline.
One strategy to withstand such changes in salt concentration is to allow the body's osmotic pressure to vary with that of the environment. Organisms that do this, and therefore do not maintain homeostasis, are said to be osmoconformers. Most marine invertebrates are osmoconformers. In contrast, marine mammals and most fish are osmoregulators, maintaining homeostasis regardless of the osmotic pressure of the environment.
However, as the salt concentration of body fluids in an osmoconformer changes, various body functions are affected, such as the activity of enzymes. For normal functioning to be maintained, another body function must be changed in a way that compensates for the change in enzyme activity.
One example of enantiostasis is when a change in salt concentration in the body fluid, which reduces the efficiency of an enzyme, is compensated for by a change in pH, which increases the efficiency of the same enzyme
