Examination of water quality from the Yarqon river (central Israel) using the glass slide method to define algal vegetative activity (in vitro)

The provision of uniform, artificial substrates for periphytic colonization has a long history, and it is the most widespread of all the techniques applied to study algal periphyton activity. The Yarqon River is one of the largest coastal rivers in Israel. An experiment for the determination of algal vegetative activity in the artificial pools, using the glass method, from the Yarqon River stations was conducted during the period from 8.11.06 till 6.12.06. During the experiment we revealed the colonization's speed of substrates and the activity of self-purification processes at different stations of river. The artificial colonization of substrates by algae during the rainy period takes about 2-3 weeks. Chlorophyll, which was used as a trophic marker, revealed ultra-oligotrophic or oligotrophic levels in pool I. At pools II and III levels were either oligo-mesotrophic or eutrophic. These results corresponded to the gradient of organic matter in each experimental pool.The algal diversity found on glass slides represented about 10-15 species for each pool. During the experiment, cells from pool I were about 1-2.5 μm³, and at pool Ii cells were about 0.1-1.4 μm³. The increase of the ecosystem's entropy is indicative of environmental stress. This criterion, which is based on diversity dynamics, cell counts, and biomass may be used for monitoring the quality of water and aquatic ecosystems in the rivers of Israel.