EUTROPHICATION IN LAKE KARIUT

EUTROPHICATION IN LAKE KARIUT.
RAMSES R. ABDALLA. AMIN A. SAMAAN AND MARY G. GHOBRIAL
National Institute of oceanography and Fisheries,

Alexandria.

ABSTRACT
LaKe Mariut shows a quite drastic eutrophication
phenomena. It is a shallow bracKish semi-closed environment
which receives a constant high input of industrial wastes
and sewage effluents. The Lake water is characterized by
high nutrient load particularly P04 and NH3• (average 1.34
mg P0 -P/l and 0.39 mg NH3 -N/l). as well as a wide 4 amplitude of dissolved oxygen concentration (0.0 • 15.33 ml
02 /l). The amountI of dllsolved organic metter end
suspended detritus are allo high (average 43 mg 02 consumed
/l). As a result of excessive nutrient impact, the lake
sustained high density of phytoplankton all the year round
with av.rage annual of 55,940 x 103 ~nits /1. The
phytoplankton cOl1lllUni ty is charactarlzed by low spedes
diversity and regular pattern of blooms, dominated by
pollution tolerant algal species such as Merismopedia
tenuf.lli.., spirul ina platensi., Cyclotella ~in”ana,
Planktosphaeria gelatinosa, Crucigenia tetrapedia, Oeeystil
borgei, lCirchnerielia 8pp. and Eugel_ granulatli. The
simple correlation coefficients were used to measure the
relationship between variations in phytoplankton standing
crop versus some physical and chemical parameters of lake
water. Data showed that P04 and NM3 exist at levels beyond
their limiting growth concentrations.