Project Director

Leasi, Francesca

Department Examiner

Craddock, J. Hill; Walker, Rich

Department

Dept. of Biological and Environmental Sciences

Publisher

University of Tennessee at Chattanooga

Place of Publication

Chattanooga (Tenn.)

Abstract

Salinity is a shaping force of aquatic biodiversity, and ongoing climate change and unsustainable water-management practices are causing salinity-induced stress across coastal ecosystems. Meiofauna are small (45-1000 μm), taxonomically diverse aquatic invertebrates that are vital to ecosystems and highly responsive to environmental disturbances, making them ideal for assessing the effects of changing salinities on community structure. This study investigated how meiofaunal biodiversity (ASV richness, Faith’s phylogenetic diversity, and community composition) responded to natural salinity gradients along streams flowing into Biscayne Bay, South Florida, which is a region particularly vulnerable to salinization due to sea-level rise, altered hydrology, and watershed modification. Water column and sediment samples were collected from 13 sites across three streams, each spanning from oligohaline (near freshwater) to euhaline (marine) conditions. Meiofaunal communities inhabiting each sample were analyzed using 18S rRNA gene (V9 region) DNA metabarcoding via the QIIME2 and DADA2 pipelines. Salinity and other environmental variables were significant predictors of the biodiversity metrics in planktonic and benthic habitats, and community structures were distinctly shaped by salinity. This research adds to the limited body of literature using metabarcoding to study meiofauna-salinity dynamics, and as the first record of meiofauna in Miami, provides a foundation for their biodiversity in South Florida’s coastal streams.

Acknowledgments

This material is based upon work supported by the National Science Foundation under Grant No. 2412308. I am grateful to the Tucker Foundation for supporting me with their scholarship for Stream Ecology research during the Fall 2024 through Spring 2026 semesters. I am deeply appreciative of Dr. Francesca Leasi for her close mentorship and support throughout the two years I have been a member of her lab and for providing me with many opportunities for growth and the development of skills that have helped me mature as a scientist. Thank you to Dr. Hill Craddock and Dr. Rich Walker for being on my committee and for reviewing my thesis with keen eyes.

Degree

B. S.; An honors thesis submitted to the faculty of the University of Tennessee at Chattanooga in partial fulfillment of the requirements of the degree of Bachelor of Science.

Date

5-2026

Subject

Meiofauna; Salinity--Environmental aspects; Stream ecology

Keyword

18S rRNA; biodiversity; community ecology; DNA metabarcoding; meiofauna; salinity gradient

Discipline

Environmental Indicators and Impact Assessment

Document Type

Theses

Extent

iii, 71 leaves

DCMI Type

Text

Language

English

Rights

http://rightsstatements.org/vocab/InC/1.0/

License

http://creativecommons.org/licenses/by-nc-nd/4.0/

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