Analyses of physico-chemical characteristics and phytoplankton communities of Lake Nasser during the last two decades

Abstract

Lake Nasser is one of the largest man-made lakes in the world. The creation of Lake Nasser, due to the impoundment of the River Nile in Southern Egypt, was accompanied by alterations in the environmental conditions that consequently affect the biota. Such alterations lead to corresponding changes in the diversity, abundance and distribution of the phytoplankton community. Therefore, the phytoplankton populations were followed and investigated in Lake Nasser. The phytoplankton community structure revealed a floristical diversity and is composed of various planktonic algal taxa appertaining to the divisions: Chlorophyta, Bacillariophyta (diatoms), Cyanophyta (cyanobacteria), Dinophyta (Dinoflagellates) and Euglenophyta. Chlorophyta contribute more taxa to the phytoplankton than any other groups. However, diatoms and cyanobacteria are numerically the main components and alternate in dominance of the community. Dinoflagellates persist as frequent forms and the euglenoid algae are very scarcely represented. Remarkable spatial (horizontal and vertical) as well as temporal (seasonal) variations are recorded in the distribution of phytoplankton. Pronounced variations in the vertical distribution of the phytoplankton standing crop appear during the periods of thermal stratification (late spring, summer and early autumn). However, diatoms and cyanobacteria remain the most influential groups also in the vertical distribution of the phytoplankton. Water blooms are occasionally observed in limited areas of the southern region of Lake Nasser mainly due to the florishment of the cyanobacterium Microcystis aeruginosa.

Euglenoids from the El Farafra Oasis (Western Desert, Egypt)

“…From the El-Farafra Oasis, Shaaban et al (2015) (Shaaban 1994) which focused mainly on the River Nile and its two branches, pools, lakes and ditches, from which 42 species were reported, 9 of which are considered extinct. Further contributions by El Otify et al (2003), Gaballa (2014) and El-Kassas and Gharib (2016) also supported this observation. Saber (2010) recorded 14 cosmopolitan species from the main branch of the River Nile and its Rosetta branch.…”

First Tithonian Record of Perforated Pediastrum Meyen S.L. Species Within Early–diagenetic Carbonate Concretions From the Vaca Muerta Formation, Neuquén Basin, Argentina. Implications for the Palynological Analysis of Fine-Grained Rocks

“…Pediastrum simplex var. biwaense also occurs in temperate to tropical regions: Andulasia in Spain (Fanés Treviño, 2008), Andhra Pradesh in the southern coastal region of India (Naidu et al, 2018), Nasser Lake in the northeast of Africa (El-Otify et al, 2003), among others.…”