Aquatic Sciences Meeting, Albuquerque 2001

SS10 Human Activities and Their Effects on Aquatic Ecosystems (Environmental Connections; Science and Society Connections)

Date: Monday, February 12, 2001, Time: 2:30:00 PM

Location: La Cienega

Gooden, W, S, Bowling Green State University, Bowling Green, USA, wbsg@gateway.net

Lowe, R, L, Bowling Green State University, Bowling Green, USA, lowe@bgnet.bgsu.edu

Belanger, S, E, The Procter & Gamble Experimental Stream Facility, Milford, USA, belanger.se@pg.com

Kemp, M, J, Kansas State University, Manhattan, USA, mjkemp@lter-konza.konza.ksu.edu

ENDOPELIC ALGAL RESPONSES TO SURFACTANTS:COMMUNITY STRUCTURE AND MAT ARCHITECTURE

Vertical motility among endopelic diatoms is well-documented. Presumably, diatoms move in response to changing vertical resource gradients within sediment mats. Still, much is to be discerned about the frequency and conditions under which diatoms move. We investigated potential chemical influences underlying endopelic, diel vertical migration. The study took place in stream mesocosms at Procter & Gamble's Experimental Stream Facility. After an eight week periphyton exposure to a surfactant, we obtained in situ vertical O2 microprofiles from matured periphyton mats under light-dark periods, using O2 microelectrodes. The mats were harvested and processed for scanning electron microscopy to examine diel vertical positions of motile diatoms. Diatom depth-distribution was compared to O2 microprofiles to establish any correlation. Besides in situ biogenic photosynthesis, stream water may be another O2 source in the mats. Mats remained oxygenated within the first millimeter even under dark conditions. Oxygen distribution varied vertically and horizontally. Most algal biomass appeared in the top millimeter in mats harvested during light conditions. The data suggests that oxygen concentration regulates algal-depth distribution in mats accruing in these mesocosms.

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Aquatic Sciences Meeting, Albuquerque 2001

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