Water quality and phytoplankton communities in Lake Qarun (Egypt)

Abstract

Lake Qarun is a closed saline lake in the northern part of El-Fayoum Depression (Middle Egypt) at the margin of the Great Western Desert. It is almost entirely sustained by inflow from the Nile River and, during the 20th century, lake water salinity has increased strongly. Physico-chemical characteristics and phytoplankton periodicity in the lake were monitored during 2001. All the water quality variables measured showed considerable seasonal variation, and quantitative and qualitative differences in phytoplankton communities were recorded. The maximum crop density was in August, whereas lowest values occurred in December. Highest crop densities coincided with a high abundance of Bacillariophyceae. The Bacillariophyceae were most diverse with 23 species, Aquat. Sci. 67 (2005) 350 -362 Aquatic Sciences then Chlorophyceae with 16, Cyanophyceae with 8, and Chrysphyceae and Dinophyceae with one species each. Despite being a saline inland lake, the open-water phytoplankton communities were composed of some marine/ brackish forms but mainly of freshwater communities tolerant to high salinity. The identified phytoplankton species indicate a tendency towards eutrophy but total crop densities were relatively low compared with eutrophic lakes elsewhere. Light limitation by suspended solids as well as hydrological related factors are believed responsible for the relatively low phytoplankton abundance. The lake appears to be ecologically unstable and careful limnological monitoring is recommended.

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“…Similar trend was also reported by Fathi and Flower. 31 Calcium was found maximum (8.28±2.02 mg.l -1 ) in summer season at S 1 and minimum (4.01±1.13 mg.l -1 ) in monsoon at S 2 . Magnesium was found to be maximum (3.82±0.11 mg.l -1 ) at S 3 in summer season and minimum in monsoon season at S 1 , S 3 and in autumn season at S 3 .…”

Changes in the phytoplankton community of a coastal, hyposaline lake in western Anatolia, Turkey

“…Phytoplankton species found in freshwater were also identifi ed in hyposaline-alkaline Lake Burdur, Turkey (Girgin et al 2004). Although Lake Qarun is strongly saline, many species were recognized to be freshwater (e.g., Ankistrodesmus spp., Scenedesmus spp., Pediastrum boryanum) (Fathi and Flower 2005). The chlorophyte Monoraphidium minutum was the dominant species in hyposaline Lake Alchichica, central Mexico (Oliva et al 2001).…”

Ostracods and the Holocene palaeolimnology of Lake Qarun, with special reference to past human–environment interactions in the Faiyum (Egypt)

“…These improvements led to a large increase in the human population, and the Faiyum became a thriving agricultural community once again. Modern Lake Qarun water is saline (mean TDS in 2001 was 34.5 g l -1 ) and of Na-(Mg)-SO 4 -Cl brine type (Fathi & Flower, 2005).…”