Ia. Arif, COMPOSITION OF BLUE-GREEN-ALGAL MATS AND WATER CHEMISTRY OF THE BANI-MALIK HOT-SPRING (GIZAN PROVINCE), SAUDI-ARABIA, Kuwait journal of science & engineering, 24(1), 1997, pp. 109-122
The ecology of microbial mats, water chemistry and invertebrates in th
e Bani Malik hot spring (Gizan Province) Saudi Arabia are presented. V
arious forms of thick algal mars were identified. They exhibited signi
ficant growths and occurred in a temperature gradient (45-50 degrees C
) in a natural stream. An abundance of Phormidium/Oscillatoria, Synech
ococcus lividus and Calothrix/Pleurocapsa occurred as visually-obvious
mats, In the mats were discrete groupings which were recognizable by
their morphologies and color discriminations. These outgrowths were re
garded as a nuisance by the area development authority. A community ap
parently not previously recorded in the thermal springs of Saudi Arabi
a was abundant in a deep thermal pool. This consisted of clusters of p
edicellate nodular mats predominated by Calothrix thermalis (90%) with
the remainder contributed by Pleurocapsa minor (10%). A cross-section
of the mat revealed striking laminations composed of an outer thin co
ver (Synechococcus spp.), followed by a middle thick zone (Calothrix t
hermalis/Pleurocapsa minor) and finally a central zone (calcite crysta
ls) of a rather firm consistency. The other biological structure consi
sted of intermittent old and dead filaments of C. thermalis, with a fe
w insect larvae associated within the mat. The overwhelmingly lothic a
lgal community in a hydrogen sulfide-rich thermal pool appeared to pla
y an active role in the photosynthetic activity, resulting in aeration
(O-2 = 3.5 mg/l) of the waterbody. The water may be characterized as
slightly to-moderately alkaline with high concentrations of reactive-S
i (44 mg/l), Cl- (217 mg/l) and SO2-4 (613 mg/l). The water of the spr
ing orifice contained hydrogen sulfide (> 5 mg/l).