Ecological studies on some freshwater habitats in the mid-western region of Saudi Arabia

الملخص EN

A lon gitudinal study was con du cted on so me ecolog ica l aspec ts of freshw ate r habit at s in the mid-west e rn region o f Saudi A ra bia .

A tot al of 14 habitat s (9 in Hijaz highl ands and 5 in Tiham ah lowl an ds) wer e sampled seasona lly from autumn 19/{7 to wint er 19/{/{1l989 .

Fre shwa te r fau na and flora sha ll be reco rde d in a se ries of stud ies.

In thi s study data o n snails a re pr esented .

Biomphuluria arabica was the most ab unda nt sna il in Hij az high lands (with few Bulinus 1rI1I/ ca11lS) hut was not recorded in T iha rna h lowlands.

Bulinus beccarii and Bulinus truncutus we re recor ded in o nly two ha bita ts in Tiha ma h lowlands.

Th e max imum numbe r of snai ls was re corded in aut umn 19/{7 an d winter 19/{711 ()/{8 wh ile dry nes s led to death o f sn ails a t othe r seaso ns of th e yea r.

Molluscicidal ap plicat io n al winter.

rains and flood s led to death or flush ing o f sna ils in Hi jaz highlan ds.

Rainf all and tempe ra ture a rc th e main limiting fac to rs for the dist ribution and surviva l of sna ils.

Sna ils ar e o nly abundant during we t seaso ns of the year a nd Biomphalaria arabica favo urs a tempe ra ture ran ge of 17-2()OC while Bulinus bee carii favo ur a high er tempe rature ra nge of 30-3h "C.