Project Title

Diatom Community Analyses for use in Water Quality Assessment

Presentation Author(s) Information

Anna AgiFollow

Faculty Mentor(s) Name(s)

Dr. Kalina Manoylov

Abstract

Diatoms, a common group of algae, survive and function as robust biological indicators in lotic environments. They have cell walls made of hydrated silica, or glass, with distinct morphological features allowing accurate identification to the lowest taxonomic level is essential. USGS Shenandoah valley project assessed Best Management Practices (BMPs) implemented to restore water quality I streams within watershed and lower nutrient runoff towards the Chesapeake Bay of the Atlantic Ocean. Algal community data complemented macroinvertebrate and physiochemical data. Diatom community metrics and data analyzed in streams with BMPs were assessed. Fourteen streams were sampled, materials were processed following standard protocols, and diatoms were enumerated as composite samples. At random, 3 streams with 3 field sample replicas each, were selected and compared to the composite sample analyses. Within-stream replicas had high similarity, but lower species richness. Species richness and Shannon diversity were significantly higher in the composite samples (p<0.001). Within replicated counts, individual species abundances were consistent, no taxon had higher than 34% relative abundance. Achnanthidium deflexum (Reimer) Kingston, a common low nutrient indicator was documented in all samples and stayed at 12-14% relative abundance regardless count type. Evenness stayed high ranging from 69.4 to 89.6%. Percent similarity based on species composition was high, 50.5-58.6. Results of this research suggest that field replicas are useful for benthic community patchiness assessment but take longer time. A single composite sample can be used to save time and, dependent on the research objective, can show informative change in species richness. In BMP streams, diatom community indices and low abundance of Naviculoid and sediment tolerant diatoms like Nitzschia suggested reduction in nutrients from agricultural areas around the Chesapeake Bay watershed, reducing risk of harmful algal blooms.

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Diatom Community Analyses for use in Water Quality Assessment

Diatoms, a common group of algae, survive and function as robust biological indicators in lotic environments. They have cell walls made of hydrated silica, or glass, with distinct morphological features allowing accurate identification to the lowest taxonomic level is essential. USGS Shenandoah valley project assessed Best Management Practices (BMPs) implemented to restore water quality I streams within watershed and lower nutrient runoff towards the Chesapeake Bay of the Atlantic Ocean. Algal community data complemented macroinvertebrate and physiochemical data. Diatom community metrics and data analyzed in streams with BMPs were assessed. Fourteen streams were sampled, materials were processed following standard protocols, and diatoms were enumerated as composite samples. At random, 3 streams with 3 field sample replicas each, were selected and compared to the composite sample analyses. Within-stream replicas had high similarity, but lower species richness. Species richness and Shannon diversity were significantly higher in the composite samples (p<0.001). Within replicated counts, individual species abundances were consistent, no taxon had higher than 34% relative abundance. Achnanthidium deflexum (Reimer) Kingston, a common low nutrient indicator was documented in all samples and stayed at 12-14% relative abundance regardless count type. Evenness stayed high ranging from 69.4 to 89.6%. Percent similarity based on species composition was high, 50.5-58.6. Results of this research suggest that field replicas are useful for benthic community patchiness assessment but take longer time. A single composite sample can be used to save time and, dependent on the research objective, can show informative change in species richness. In BMP streams, diatom community indices and low abundance of Naviculoid and sediment tolerant diatoms like Nitzschia suggested reduction in nutrients from agricultural areas around the Chesapeake Bay watershed, reducing risk of harmful algal blooms.