What kind of coastal systems do we include in the definition of an estuary? In a simple description, it has been considered that estuaries are systems with a significant riverine input and free connection to the sea, involving in its essence a salinity gradient from freshwater to marine waters. However, in nature we can find several variations of this assumption, such as intermittently open and closed coastal lagoons and lakes, as well as situations of hypersalinity, which are influenced by freshwaters. These are especially relevant in the southern hemisphere, in countries such as Australia and South Africa. However, despite being frequently disregarded, similar ecosystems can be found worldwide, including in Europe. We can now find several articles in the literature arguing that, although not classical, these systems should be considered as estuarine ecosystems, leaving the scientific community with the challenge of revising the existent definitions.
Last date updated on June, 2014