الفهرس 
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Abstract
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SUMMARY
Lake Qarun lies at the lowest part of El-Fayoum
depression in the western desert between longitudes 30° 24’
and I 30° 49’ E and latitudes 29° 29’ and 29° 34’ N . The
area of Lake Qarun is about 55,000 feddans . It extends
for about 40 Km long from east to west and 5.7 Km as a
mean breadth .
The lake receives drainage water from the neighboring
cultivated lands through a system of drains. El-Bats and
El-wadi drains are the main channels joining the lake at
the east and mid-south sides respectively .
The following is a summary of the obtained results .
PhysicQ-Chemical features of the lake;
1. Temperature:
Water temperature follows that of the air The
lowest average of surface water temperature was 12.7 0c
during winter while the highest attained 31°C calculated
during summer .
2. Transparency :
Lake’s water transparency is relatively low (average
35 Cm) . Secchi disc reading varied from 5 to 110 cm. The
highest value was recorded in station VI , while the
lowest was observed in station I and VIII .
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3.Depth :
Water depth ranged from few centimeters beSide shores
to 700 cm at station VI which is the deepest station .
4.Nature of bottom:
Bottom sediments of Lake Qarun is nearly homogenous .
Most of the studied stations have mUddy bottom except
those neighbouring the drains (have sandy mud bottom ).
Benthic fauna in Lake Caryn and the feed~ng dkains ;
1. Twenty Species of benthic invertebrates were recorded
in Lake Qarun belonging to 18 families and 10 orders.
6 of these species (30 % of the species nUmber) are
new to the area. These are one coelenterate
(Aiptaslogeton cf comatuS) recorded for the frist
time throughoutthe present stUdy,not only from Lake
Qarun , but also from the whole Egyptian waters , one
polychaete (Polydora ligni), one amphipod
(Corophium ascherusicum) , one deacopd (Bracbynotus
seXdentatus , one gastropod (Nassarius cuvierl) and
one bivalve (Venerupis aurea) . Crustacea are the
main zoobenthos component in the lake followed by
polychaeta , Mollusca and less so Coelentrata .
2. EI-Bats and El-wadi drains are relatively poor than
the lake. In them (8) species belonging to 6 orders
of Annelida , Arthropoda and Mollusca were recorded.
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3. The average population density of benthic organisms in
the lake attained 1676 organisms/m2/year weighing
81.23 G.F.W./m2/year . The highest denSity was
recorded in station VI with an average of 3925 , while
the lowest P.o. and biomass (210 individuals/m2/year
weighing 18.35 G.F.W./m2/year were recorded in station
VII .
4. Winter was the most productive season (produced 2058
organisms/m2/year ) allover the whole area , while
spring was the poorest .
5. Concerning biomass, the lowest value was observed
during Winter While the highest one (115.39 G.F.W./m2)
was observed during autumn .
6. Average P.o. and biomass of benthos in El-Bats Drain
(2220 organisms/m2 weighing 6.44 G.F.W./m2 ) was low
when compared with the corresponding values in El-Wadi
Drain (3690 organisms/m2/year weighing 344.13
G.F.W./m
2
). The annual standing crop in the drains
is higher than that observed in any station in the
lake during the whole investigated period .
7. Arthropoda (represented by Crustacea) was the dominant
benthic phylum in the lake’s community. They
represented about 69.98 % of the P.O. and 35.08 % of
the biomass of the total benthos. MaXimum distribution
was recorded at station VI during winter. Numerically,
Corophi um ascherus.t. cum was the mOist important
crustacean species. It constituted 81.23 % of the
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glaucumj . The last species represented the main
biomass (30.6 %) of the total benthos in the lake.
In the feeding drains I Mollusca constituted about
14.36 % and 97.19 % , respectively I of P.O. and
biomass of the total benthos in El-Wadi Drain and 1.35
% and 51.39 % respectively of the total P.O. and
biomass in El-Bats Drain. They were mainly represented
by 3 gastropods (Theodoxus niloticus I Cleopatra
bUlimoides and (Physa acuta ) and one bivalve namely
Corbicula consbrina.
10. Colentrata was less represented in the lake if compared
wi th other benthic organisms. It consti tute about 5.54
% and 1.26 % of the total benthic P.O. and biomass
respectively . This group was represented by one odd
species of sea anemone namely Aiptasiogaton cf comatus.
11, Lake Qarun is a fertile lake in benthic organisms.
Both P.O. and biomass of zoobenthos were higher when
compared with other Egyptian lakes .
The present stUdy recommends station VI as a sUitable
site for a bottom feeders fish farm. As well I the
high production of the bivalve Cerastodexma glaucum
from the lake and specially station VIII encourages
the exploitation and aquaculturaing of this edible
species in Lake Qarun .