Factors controlling the deformation of benthic foraminifera in the Manzala lagoon, Egypt

Abstract Morphological deformations among hyaline and porcelaneous benthic foraminiferal were observed at stations with high contents of trace metals within the Manzala Lagoon. Energy Dispersive X-ray Analyses (EDX) were conducted on deformed and non-deformed specimens of this population. Deformed Adelosina sp. specimens show high sulfur, magnesium, iron and low copper content. The deformed Ammonia tepida show high aluminum, chloride, calcite and copper in the shell. Analyses of non-deformed foraminifera tests at unpolluted localities show that A .  tepida displays high calcium content only, whereas Adelosina sp. shows calcium and magnesium. It is worth mentioning that the non-deformed tests of both species are free from copper and sulfur. We conclude that the low salinity and/or high trace metals in the western and southern regions of the Manzala Lagoon are the main cause for the reduction in overall size of the foraminiferal shells. Porcelaneous Adelosina sp. is very rare (0 to 2%) and mainly found on the northern side, where salinity increases, whereas hyaline A .  tepida is the most dominant species in the lagoon and covers more than 97% of the total benthic foraminifera.