Physico-chemical and biological characteristics of Sarabs (spring pools) in the Kermanshah Province of Iran

Sarabs (spring-fed pools) are an important natural freshwater resource in Iran where they are used for potable, agricultural and recreational purposes. A survey of 17 Sarabs was undertaken in the Province of Kermanshah to obtain data on their water quality and biology which would help inform future management of these multifunctional resources. These Sarabs differed greatly in size (50-30000m2 surface area) and were situated at altitudes of between 622 and 1697 m above sea level. The average dissolved oxygen content and pH of the water was between 4.5 and 10mg O2/l, and 6.95 and 7.6 respectively. The Sarabs differed particularly in their dissolved solids content from 100?S/cm (detectable limit) to 600?S/cm. Four Sarabs appeared to be polluted by biodegradable organic matter. An Ekman grab was used in June 2003 to sample the benthic macroinvertebrate faunas. Average population densities, based on the numbers of animals retained by a 600?m mesh sieve, were between 2068 and 21531/m2. Fifty-eight taxa (mainly genera) were identified. Of these, 65% were molluscs, oligochaetes and chironomids. There was relatively little similarity amongst the faunas of the individual Sarabs, but seven taxa occurred in more than half those sampled: Gammarus pulex, Tanytarsus, Eukiefferiella, Tubifex, Erpobdella, Viviparus and Dugesia. The observed distribution of the macroinvertebrates recorded in this survey was largely unexplained by the water quality variables (COD, BOD5, DO, electrical conductivity, pH) measured. Taxon richness for the individual Sarabs differed from 5 to 21. Larger Sarabs tended to support more taxa than the smaller Sarabs