Where would there be a greatest need for osmoregulation?

The greatest need for osmoregulation occurs in organisms living in environments with fluctuating salinity, such as estuaries, where freshwater meets seawater. Aquatic animals like fish and amphibians must constantly regulate their internal salt and water balance to survive in these dynamic conditions. Additionally, terrestrial organisms in arid environments face significant challenges in maintaining water balance due to limited water availability. Both scenariOS highlight the importance of osmoregulation for survival and physiological function.