Response of benthic foraminifera to coastal protection of the western coast of Alexandria, Egypt

Abstract

The construction of breakwaters system in the Nakheel coastal area (west of Alexandria, Egypt) were completed in 2003 to develop a secure area for swimmers and recreational activities. The main objective of this work is to assess the influences of this coastal defensive structure on the distribution of benthic foraminiferal communities. Thirty-two near-shore sediments samples were collected in winter and summer (2011) to investigate the benthic foraminifera and sedimentological (grain size, total carbonate and total organic carbon) characteristics. The epiphytic species dominated foraminiferal assemblages in both seasons. The accumulation of massive quantity of seaweeds and macroalgae in addition to hydrodynamics in the sheltered leeside area are direct impacts of the breakwaters system. In turn, these biotic and physical variables are responsible for cross-shore transport of benthic forams to near-shore area and their distribution along-shore. Two mechanisms are suggested for forams' transport to the near-shore area; the biotic mechanism during winter via attaching seaweeds and macroalgae, and the physical mechanism in which the foraminifera are transferred as bed-load through cross-shore transportation, particularly in summer. This study suggests that the breakwaters system in addition to weather conditions govern winter-summer and spatial variations in foraminiferal assemblages in the protected Nakheel near-shore coastal area.