Aa. Alhomaidan et Ia. Arif, ECOLOGY AND BLOOM-FORMING ALGAE OF A SEMI-PERMANENT RAIN-FED POOL AT AL-KHARJ, SAUDI-ARABIA, Journal of arid environments, 38(1), 1998, pp. 15-25
An account of seasonal succession of bloom-forming algae over a period
of 3 consecutive years (1992-1995) is described in relation to the tr
ophic changes taking place in a semi-permanent rain-fed pool at Al-Kha
rj, Saudi Arabia. Population dynamics from the two contrasting arid ec
osystems show varied degrees of changes in water chemistry and algal f
lora. Recovery of algal blooms after a few flashflood events can be de
scribed as a model of temporal succession in the semi-permanent/desicc
ated water body. Morphometric properties and mesotrophic planktonic bi
ota were restored within 2-3 weeks of rainfall (5-10 cm water deposite
d). The dominant and the first to emerge was the bloom-forming green a
lga Carteria multifilis followed by Micratinium pusillum. A gradient s
easonal succession from relatively mesotrophic to hypertrophic was rec
orded. Subsequently, the blue-green algae Oscillatoria limnetica and M
icrocystis aeruginosa succeeded resulting in bluish-green to drab oliv
e colourization to the water. Altogether, 32 species are reported, c.
30% of which are newly recorded to the Saudi Arabian algal flora. Emer
gence and survival of consistent flora was positively correlated with
water quality and seasonal succession. (C) 1998 Academic Press Limited
.