A study of biofilm in a second order tropical stream, Njoro River, Kenya

Author(s): Wairimu A. Muia, Gernot Bretschko, Gerhard J. Herndl
Abstract: Between January and December 1999 the extent of biofilm development has been studied at two sites (muddy sediment site [A] and sandy sediment site [B]) in Njoro River, Kenya. Grain size, organic matter and bacterial abundance were determined at different depth layers of the sediment. Particulate carbohydrate concentrations were measured as an indicator of biofilm development in the sediment. Additionally, the development of the biofilm was investigated by placing glass slides at rock and sediment surfaces and in different sediment depth layers. Our first results for sediment samples collected in January 1999 and growth on slides exposed for 28 days in March 1999 is presented. Grain size analysis revealed that sediment particles < 1 mm contributed between 82 to 91% at site A and 45 to 67% at site B depending on the sediment layer. At site A, total organic matter (% weight loss on ignition) and total organic carbon (TOC) were more or less constant with depth while both parameters significantly decreased with depth at site B. Total organic nitrogen (TON) was detectable at all depth layers at site A but only in the top 40 mm layer at site B. Bacterial numbers were highest in the top 40 mm layer at both sites. Bacterial abundance of 3.95 ± 5.96 × 10⁸ and 4.10 ± 3.88 × 10⁸ cells g^-1 dry sediment were recorded at site A and B, respectively. For both sites, highest concentrations of colloidal carbohydrates occurred in the top 40 mm layer, but concentrations were more or less constant below. Bacterial abundance on glass slides was higher on slides placed on rock surfaces than on fine sediment surfaces or within fine sediments.
Organisation(s): Functional and Evolutionary Ecology
External organisation(s): Egerton University, Österreichische Akademie der Wissenschaften (ÖAW), Royal Netherlands Institute for Sea Research
Journal: International Review of Hydrobiology
Volume: 88
Pages: 372-384
No. of pages: 13
ISSN: 1434-2944
Publication date: 08-2003
Peer reviewed: Yes
Austrian Fields of Science 2012: 106026 Ecosystem research
Keywords
ASJC Scopus subject areas: Ecology, Evolution, Behavior and Systematics, Aquatic Science
Portal url: https://ucrisportal.univie.ac.at/en/publications/a-study-of-biofilm-in-a-second-order-tropical-stream-njoro-river-kenya(8d18e05a-3a48-47dd-922b-fe24c92a09a1).html