The effect of dried and cracked sediment on the availability of phosphorus in a coastal lagoon

Caimanero Lagoon (Sinaloa, México) is subjected to alternate periods of low water and flooding. In the first case, more than 70% of the lagoon is dry, cracked and colonized by halophytes to a variable proportion. During the dry season, mineralization of organic matter and reavailability of phosphorus takes place to a great extent. So far, the effect of dried and cracked sediment on the reincorporation of phosphorus to the coastal lagoon ecosystem has not been evaluated. This work is the result of experiments which emulate natural conditions present during the dry season and the beginning of the flood season under the influence of tidal flux. The availability of phosphorus (orthophosphates and soluble phosphates) was significantly increased in the dry and cracked material; this phosphorus is derived from the mineralization of organic matter present in the sediment. The amount of soluble organic matter also increased during the dry season. The sedimentary drying and cracking process contributes significantly to estuarine productivity.