Comparison of epilithic and epixylic biofilm development in a boreal river

• Published in: Freshwater biology 1991-02, Vol.25 (1), p.179-187
• Main Authors: SINSABAUGH, ROBERT L., GOLLADAY, STEPHEN W., LINKINS, ARTHUR E.
• Format: Article
• Language: English
• Subjects: Animal and plant ecology; Animal, plant and microbial ecology; Biological and medical sciences; Freshwater; Fundamental and applied biological sciences. Psychology; Invertebrates
• ISSN: 0046-5070; 1365-2427
• DOI: 10.1111/j.1365-2427.1991.tb00483.x

1. We assessed substratum effects on lotic biofilm development by placing glass and white pine sampling units in a fourth‐order boreal river, and analysing, at 6‐week intervals, upper‐surface biofilms for ATP, chlorophyll, ergosterol, and the activities of nine exoenzymes. 2. All parameters, except chlorophyll standing stock (range 80–320 μg dm−2) and β‐xylosidase activity (range 0.4–4.8 μmol h−1 dm−2), were significantly greater for epixylic biofilms than for epilithic ones, but the magnitude of the increases varied from 2 to 5 fold, showing that, even under similar hydrodynamic conditions, epilithic and epixylic biofilms are structurally and functionally distinct. For example, ergosterol concentrations ranged from undetectable to 0.93 μg dm−2 for epilithon and from 11–49 μg dm−2 for epixylon; corresponding ranges for ATP were 1.6–3.7 (epilithon) and 4.2–7.7 μg dm−2 (epixylon), for acid phosphatase activity: 2.3–4.9 and 20–41 μmolh−1dm−2, and for alkaline phosphatase activity: 1.9–8.1 and 29–150 μmol h−1dm−2, respectively. 3. The more extensive epixylic development was attributed to utilization of the wood substratum as a supplemental carbon source and to a higher density of microbial attachment sites.