The pollen record in a sediment core from Manzala lagoon on the Nile delta coastal margin of Egypt, deposited from ca. AD 1860 to 1990, indicates rapid coastal wetland vegetation responses to two primary periods of human activity. These are associated with artificially altered Nile hydrologic regimes in proximal areas and distal sectors located to ∼1200 km south of Manzala. Freshwater wetland plants that were dominant, such as Typha and Phragmites, decreased rapidly, whereas in the early 1900s, brackish water wetland species (e.g., Amaranthaceae) increased. This change occurred after closure of the Aswan Low Dam in 1902. The second major modification in the pollen record occurred in the early 1970s, after Aswan High Dam closure from 1965 to 1970, when Typha pollen abundance increased rapidly. Massive population growth occurred along the Nile during the 130 years represented by the core section. During this time, the total volume of lagoon water decreased because of conversion of wetland areas to agricultural land, and input of organic-rich sediment, sewage (municipal, agricultural, industrial), and fertilizer in Manzala lagoon increased markedly. Although the wetland plant community has continued to respond to increasingly intensified and varied human-induced pressures in proximal sectors, the two most marked changes in Manzala pollen best correlate with distal events (i.e., closure of the two dams at Aswan). The study also shows that the two major vegetation changes in Manzala lagoon each occurred less than 10 years after closure upriver of the Low and High dams that markedly altered the Nile regime from Upper Egypt to the coast.
You have requested a machine translation of selected content from our databases. This functionality is provided solely for your convenience and is in no way intended to replace human translation. Neither BioOne nor the owners and publishers of the content make, and they explicitly disclaim, any express or implied representations or warranties of any kind, including, without limitation, representations and warranties as to the functionality of the translation feature or the accuracy or completeness of the translations.
Translations are not retained in our system. Your use of this feature and the translations is subject to all use restrictions contained in the Terms and Conditions of Use of the BioOne website.
Vol. 27 • No. 4