Microbial stabilization of sediments in a recent Salina, Lake Aghormi, Siwa Oasis, Egypt

Stabilization of sediments by microbial mats and biofilms were studied in detail in Lake Aghormi, Siwa Oasis, Egypt. The study has shown that microbial mat assemblages, particularly filamentous cyanobacteria, with their extracellular polymeric substances (EPS) are capable of effectively stabilizing sediments. The microbial mats in the siliciclastic environments of Lake Aghormi display distinctive sedimentary structures (microbially induced sedimentary structures), including multidirected ripple marks, microbial patches, petee structures, erosional remnants and pockets, and gas domes. Scanning electron microscopy study of the sediment surface colonized by cyanobacteria revealed that filamentous types are the most effective stabilizing organisms. Filamentous cyanobacteria and their EPS construct a network, interweave depositional grains of the sediment surface, envelope the particles, and glue them together. The studied biofilm is so thick forming a spider-web structure that totally coat the particles in such a way the morphology of the particles is masked.