Variations and relationships of salinity, nutrients and suspended solids in Chelem coastal lagoon at Yucatan, Mexico

Abstract

Chelem lagoon is a typical sand barrier tropical coastal body of very shallow water located in the Gulf of Mexico side of Yucatan Peninsula characterized by strong anthropogenic activity including a seaport, urban and industrial development which affected its natural regime. The whole region is karstic with no rivers and groundwater circulation. Monthly observations of physical and chemical parameters were carried out during almost five years. Chelem lagoon has antiestuarine characteristics: the salinity increases toward the interior since there are not important inputs of fresh water, and the evaporation is high. The statistical analysis showed three different zones: west zone is characterized by high salinity values, high ammonium concentration and low human disturb; central zone has lot of water exchange between sea and lagoon that keep favorable conditions; and east zone has large variations in salinity, high ammonium and suspended materials and low oxygen, and is impacted by the human activities. Hurricane Gilbert affected the lagoon, decreasing the salinity and raising the silicate and nitrate concentrations. Salinity, ammonium, silicate and suspended solids presented annual periodicity.