ECOLOGY OF BACILLARIOPHYCEAE IN LAKE BUROLWS, EGYPT

ECOLOGY OF BACILLARIOPHYCEAE
IN LAKE BUROLWS, EGYPT
ZEINAB M. El-SHERIF, AMIN A. SAMAAN AND RAMSIS R. ABDALLAH
National Institute of Oceanography and Fisheries,
Alexandria, Egypt.
ABSTRACT
The ecology of diatoms in Lake Burollus was estimated
monthly during the Years 1978 and 1979. Bacillariophyceae
ranked as the second important component of phytoplankton in
the lake after Chlorophyceae and it cOf,tributed about 26.8 X
of their counts (average 842 thousand cells/l). It included
59 species within 23 genera and 6 families. The dominant
diatoms were Nitzschia spp. (67.6 X of the total diatom
counts) and Cyclotella ~ini_ (13.4 X), while
Melosira spp., Synedra spp. and Cocc~i. placentula
llppeared as fr’equent forms. The o\:her diatoms remained
infrequent or rare. Most of the diatoms inhabiting the Lake
hre littoral, oligohalobous halophilous species, while few
are m~soh~lobous or euhalobovs dlat~ns.
The maximum persistence of diatoms in the Lake was in
general around the southern margins nearby the land drains,
particularly in the middle and west’i!rn .. sectors. Their
numbers .,erE’ s’Jbjected to irrgular monthly fluctuatior,s
within the thrc~ ~~ctors of the Lake. They showed a general
irtCreAse in 1979, cOIi’pared with their densities during 1978.
‘.e.’.e Buotl”.· i” cclf’lside:’ecj 8S an eutrophic lake with a
»:; .. ~’Cl chlorc,c0cciil-diatom type l’if phytoplankton.