This study was carried out in 2016 to investigate the feeding on phytoplankton profile of the Nile tilapia (Oreochromis niloticus) and mango tilapia (Sarotherodon galilaeus) inhabiting Lake Nasser, and its relation to their fisheries biological parameters. Phytoplankton Preference index (PPI), Index of Relative Importance (IRI), and Straus Linear index were used to investigate the feeding patterns of the two species in the lake. Moreover, some fish biological parameters of the two species were determined in the lake different areas. The results showed that O. niloticus and S. galilaeus feed mainly on the same phytoplankton items. Bacillariophyceae was identified as the most desired phytoplankton item to O. niloticus (IRI = 12.53) and S. galilaeus (IRI=18.28). Both fish species were more selective to five species from Bacillariophyceae and five species from Chlorophyceae, while they were more avoidant to four species from Cyanophyceae at all lake's areas. The results also showed that the main fisheries biological parameters are varied significantly between the two species and through lake different areas. This study concluded that the variation in fisheries biological parameters in Lake Nasser is not related to the pattern of feeding on phytoplankton but is led by other factors (e.g. fishing practices).

Microalgae are one of the most effective sources of renewable energy production. It can grow at high rates and capable of producing oil along the year. Microalgae biomass was first suggested as a feedstock for biofuel production and received early attention for commercial application. Microalgae are expected to be a vital raw material for amino acids, vitamins and productions of valuable byproducts. The cultivation of microalgae is known to be the most gainful business in the biotechnological industry. It is a waste less, environmentally pure, energy and resource saving route. Biodiesel production from algal lipid is non-toxic and highly biodegradable. Conversion of biomass to biofuel can be achieved by different methods which are broadly classified into: thermal, chemical and biochemical methods, in addition to the large number of different agents for decomposing and hydrolysing. We can obtain the low-cost energy production from the wastewater treatment by using microalgae. Finally, biodiesel production by microalgae in Egypt is not practical at the economical level. In order to improve biodiesel fuel quality, the alga must be subjected to genetic engineering for up-regulation of fatty acid biosynthesis and/ or by down-regulation of β-oxidation. Economically, the algal biomass must be processed for bio-refinery to maximize its utilization for different applications.

The present study focused on the determination of the baseline data and correlations between biological and physicochemical variables, including the assessment of trophic conditions in Lake Qarun. The concentrations of nutrients were high, with the maxima usually in the east subarea (total nitrogen 6.40 mg dm

No abstract

The Wadi El-Rayan is a depression in the Fayoum oasis collecting agricultural drainage water from the Fayoum. Since 1973, this drainage water formed two man-made lakes. Twenty years ago, a third lake, called Lake Magic was formed. Since this newly formed lake was not yet studied, in January of 2019 we conducted research related to its physico-chemical (ion composition, nutrients, heavy metals, etc.) and biological (phyto-, bacterio- and zooplankton) characteristics. The depth of the lake ranged from 1.5 to 9.0 m, water transparency was up to 4.0 m, and the water temperature was 13.6 °C. The average salinity was 29.1 g/l, and the salinity of drainage waters from agricultural fields was 2.9 g/l. A total of 28 phytoplankton species was identified belonging to Bacillariophyceae (eight species), Dinophyceae (three species), Cyanobacteria (seven species), Chlorophyceae (nine species) and Conjugatophyceae (one species). Chlorophyll a content varied from 14.3 to 24.2 μg/l. In zooplankton, there were three species of Ciliophora, five of Rotifera, and two Copepoda as well as Nematoda and Cirripedia larvae. Salinity in Lake Magic was much higher than in drainage waters coming in the lake. This is a result of a strong salinity increase in Lake Magic after its creation due to climate aridity, and salinity may markedly increase during the next 20 years along with the sharp changes of the lake's ecosystem.