Diversity and ecology of algae from the Lower Jordan River, Israel

The Lower Jordan River stretches from the outlet of Lake Kinneret till the Dead Sea and is one of the most polluted rivers in Israel. In order to estimate the aquatic ecosystem of the northern part of the Lower Jordan River we used algal communities as biological indicators in the rainy and dry seasons of 2005 and 2007. We found 152 species of algae and cyanoprokaryotes from seven taxonomic divisions, which were mostly dominated by diatoms accompanied by the greens, blue-greens and euglenoids. The xanthophycean species Heterococcus viridis, a red freshwater alga Audouinella hermannii, and a cyanobacterium Microcrocis marina were found for the first time in Israel. In the ecological analysis we revealed groups of freshwater algae according to pH, salinity, and saprobity as well as temperature, streaming and oxygenation. Quantitative information on the relationship between species and environmental variables was obtained using CCA analysis, emphasizing the major seasonal parameters. The extent of association of species with the environmental variables vector allowed us to determine the bio-sensors and bio-indicators, which may be relevant for monitoring of pollutants in the Lower Jordan River. The combination of bio-indicational methods and statistics were effective in the determination of the main factors influencing algal diversity, as well as in revealing the indicators or bio-sensing species for the most important environmental variables.