PERIPHYTON RESPONSE IN AN INDUSTRIAL RECEIVING STREAM - LIPID-BASED PHYSIOLOGICAL STRESS-ANALYSIS AND PATTERN-RECOGNITION OF MICROBIAL COMMUNITY STRUCTURE

Periphyton were collected from three physically similar sites on an industrial receiving stream which differed in their distances from the discharge. Previous studies had established that biological effects diminished with distance downstream from the discharges. In this study, a multivariate analysis of periphyton membrane lipid profiles quantitatively verified site-specific differences in time-independent microbial community structure qualitatively suggested by algal taxonomic analyses. There were no differences in periphyton abundance among sites. Periphyton physiology was evaluated using a C-14-labeled bicarbonate and H-3-labeled amino acids dual-label incubation, with subsequent analysis of carbon partitioning into lipid compartments. Total radiolabel uptake was similar for all sites. Physiological stress was shown to be highest at the site closest to the discharges using a membrane to storage lipid synthetic ratio. High values of this ratio indicated that both the phototrophic and heterotrophic constituents were stressed, and this stress declined with distance downstream. The ability to measure algal and bacterial abundance, community structure, activity, and physiological status from a single extraction provides a powerful method to evaluate periphyton which can serve as a useful biomonitoring and toxicity assessment tool for aquatic ecosystems.