Date of Award

2012

Degree Type

Thesis

Degree Name

Master of Science (MS)

Department

Biology

Abstract

We investigated the relationship between algal taxonomy, community succession and biomass accrual and denitrification potential (DNP) within stream periphyton. Field research was conducted in 6 DuPage County, II forest preserve streams with diverse physical and chemical characteristics and in an experiment in the artificial stream facility at Loyola University Chicago in which 2 sets of streams were amended with nutrients and compared to an unamended set of streams. Algal communities in the field study streams were sampled over 12 weeks late spring/summer and NMDS ordination plots identified 4 distinct communities. Correlations with algal community NMDS axis scores and the relative abundances of algal species in all the streams, identified several taxa including Achnanthidium lanceolatum, Achnanthes ploenensis and A. minutissimum that were associated with samples with higher DNP. The artificial stream control and treated stream communities, sampled over 10 weeks, diverged after 2 weeks of development. Nutrient amendments, particularly PO4-P, in the treated streams led to treated stream communities dominated by Chlorophyta, and biomass accumulations double those of the control stream communities. NMDS axis scores for each set of streams and algal abundances, identified 3 algal taxa, in the amended streams, Nitzschia inconspicua , N. microcephala and , Scenedesmus spp. that were associated with DNP. Biomass accrual was most important to DNP under nutrient saturated and less disturbed conditions where the biofilm communites were less diverse. Higher levels of DNP were measured when intermediate levels of disturbance appeared to increase algal community diversity and biofilm heterogeneity. We hypothesize that, though statistically significant relationships were not evident between any algal taxa and DNP, the greater availability of environmental niches including algal organic carbon exudates, led to a greater diversity in denitrifying bacteria and that these algal/bacterial associations appeared to become decoupled with excess nutrients.

Creative Commons License

Creative Commons License
This work is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 License.

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