Inversion (Estuarine)

An inverse estuary, the setting of estuarine inversion, is one where evaporation exceeds freshwater inflow, so salinity rises from the open-sea mouth toward the upstream head rather than decreasing inland as in a normal estuary. The reversed salinity gradient drives a circulation opposite to the classic estuarine pattern: dense hypersaline water sinks and flows seaward along the bottom while less saline ocean water enters at the surface. Examples include Spencer Gulf and the Coorong in South Australia and parts of the Mediterranean Laguna Madre. Inversion is seasonal in drought-prone or arid coastal systems and stresses biota adapted to a falling inland salinity. It alters nutrient retention and larval transport.