Evaluations of Epilithic Diatoms and Biotic Index in Sakarya River, Turkey

Abstract

Diversity and ecology in the diatoms of Sakarya River were investigated between October 2009 - September 2010. As a result, Navicula radiosa Katz was the dominant taxa at the first and fourth stations. Gomphonema olivaceum (Horrn.) Brebisson, Craticula cuspidata (Kutz.) D.G. Mann, Rhoicosphaenia abbreviata (C. Agardh) Lange-Bertalot, and Nitzschia recta Hantzsch ex Rabenhorst taxa were found to be widespread throughout the research. Significant correlation was identified between SI and DI-CH and between TI and DI-CH in the epilithic diatoms. The minimum correlation was identified between SI and TI. Based on the assessments, according to Si, the fourth station was classified as 11-Ill quality class, or critically polluted. Other stations were classified as 11 quality class, or moderately polluted. According to T1, the first station was determined to be II-Ill (mesotroph-eutroph) quality class. Second, third and fourth stations were found to be III (polytroph) quality class. According to DI-CH, the fourth station was classified as quality class IV (moderately polluted), while the first, second and third stations were determined as III (less polluted) quality class. The environmental variables on the RDA diagram were selected (p<0.05) according to Monte Carlo permutation test. The first and second axis explained 89% of variation of the species in the correspondence analysis. Additionally, the first and second axis explained relationship between species and environmental variables at the rate of 34.6% and 61.1%. The RDA axes scores allow us to distinguish 5 diatom species assemblages with a total of 25 species.