Date of Award

Spring 3-10-2020

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Biology

First Advisor

Dr. Kalina Manoylov

Second Advisor

Dr. Christine Mutiti

Third Advisor

Dr. Dave Bachoon

Abstract

Surface freshwater is a scarce resource. Due to the scarcity and necessity of this resource, it is imperative that its quality is routinely monitored. One way of monitoring water quality is through biological assessments, which include examining algal assemblages. Regionally, little remains known of algal taxa in the southeastern United States. In the past, the Academy of Natural Sciences of Philadelphia (ANSP) conducted biological assessments along the Savannah River finding Gomphonema parvulum (Kützing) Kützing 1849 to be a dominant taxon rendering assessments inconclusive. Recent studies have provided evidence that species complexes and semi-cryptic taxa have been identified within the Gomphonema Ehrenberg 1832 genus and as G. parvulum. These studies have also shown that misidentifications have been made largely due to difficulty in using traditional light microscopy and biometric techniques (length, width, straie density in 10 μm). For an understanding of current water quality along the Savannah River, this study sought to investigate and resolve complexes found in a high quality habitat within the genus Gomphonema, as well as other common taxa found within the Eunotia Ehrenberg 1837, and Tabellaria Ehrenberg ex Kützing 1844 genera. We report the morphological diversity found among these taxa. We also provide a table with the biometric techniques (length, width, straie density in 10 μm, raphe form, central area characteristics, striae orientation, valve and poles shape) and supporting literature that we used to resolve G. parvulum complex representatives. In this study archives from past surveys located in the ANSP Diatom Herbarium were used to aid in resolving species complexes. Once resolved, we applied our species concepts to algal enumeration of current sampling conducted near a past Georgia College & State University (GCSU) research and reference site, Upper Three Runs Creek (UTRC). We used diatometer and composite sampling methods at our study site. These methods were chosen to compare present results with 1956 past ANSP study results and assess differences between composite and diatometer collection methodologies. Diatometer sampling was conducted over an 18-day period from March 23rd to April 9th in order to account for optimal diatometer colonization time. Composite sampling was conducted at the end of this time period upon diatometer retrieval. We calculated species richness, species relative abundances, species evenness, and diversity indices: Shannon-Wiener, Sorenson index, and Jaccard similarity index. Based on the current taxonomic approach of samples collected in 1956 and in 2018, high biodiversity at the site has been maintained with high values of community indices. Diatom species specific ecological indication demonstrate that UTRC is a nutrient rich environment and according to 2018 physicochemical data, UTRC is an acidic environment with high dissolved oxygen levels. Microbial heterogeneity of single location was confirmed in this study and sampling methodology is important for monitoring and ecological inferences.

Comments

Alignment for Table on p. 71 and text on p. 83 was altered in conversion from word document to pdf format but all information intact

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