Divergence in periphytic algal assemblages on bryophyte and bedrock substrata: potential for differential response to environmental variation

HR: 10:30h
AN: NB42B-01 [Abstracts]
TI: Divergence in periphytic algal assemblages on bryophyte and bedrock substrata: potential for differential response to environmental variation
AU: * Greenwood, J
EM: greenwood.jennifer@epa.gov
AF: University of Georgia, Institute of Ecology University of Georgia, Athens, GA 30602 United States
AU: Rosemond, A
EM: rosemond@uga.edu
AF: University of Georgia, Institute of Ecology University of Georgia, Athens, GA 30602 United States
AB: Algae grow on a variety of substrata and their response to environmental variables may be substratum-dependent. To examine the potential effects of variation in nutrient and light availability on periphyton from different substrata, algal biovolume and assemblage composition were examined on moss, liverwort and bedrock. The comparison was conducted in one nutrient-enriched and one control forested headwater stream, both sampled during months with high (May) and low (July) light availability. Assemblages were dominated by diatoms on all substrata; some filamentous reds and cyanophytes also occurred on bedrock. Ordination analysis (NMS) resulted in 3 axes explaining 86.6% of the variance in species composition and showed relatively strong separation across the three substrata. Bryophytes supported 2×10⁶-fold greater total algal biovolume than bedrock (ANOVA p<0.0001). Periphyton biovolume was generally higher in May than July on all substrata. Two-way ANOVAs month (inferred light effect), stream (inferred nutrient effect)) on individual taxa indicated higher biovolume associated with higher light and lower biovolume associated with higher nutrient concentrations for some taxa, but effects were inconsistent across substratum types. Thus, variability in substratum types in headwater streams appears to support greater diversity of periphyton and response to environmental change than would be observed from a single substratum.
DE: 9810 New fields (not classifiable under other headings)
SC: North American Benthological Society [NB]
MN: 2005 Joint Assembly