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Thesis
Sediment Biogeochemistry Response to Stingray Bioturbation in Halodule Wrightii
University of West Florida Libraries
Master of Science (MS), University of West Florida
Summer 2022
Abstract
Bioturbators like stingrays play an important role in structuring marine ecosystems, however, little is known about the effects they have at the biogeochemical and microbial level. Stingray bioturbation creates depressions or pits inside and outside seagrass beds as they feed on benthic invertebrates. Pits can persist for months and slowly fill with sediment and seagrasses regrow. This study assessed changes in sediment porewater biogeochemistry in seagrass beds between bare pits formed by stingray bioturbation and adjacent H. wrightii bed. Higher nutrient concentrations were observed in bare pits in June, where organic matter accumulation and decomposition were likely responsible. Porewater N:P ratios suggested that nitrogen was limiting in both the grassbed and bare pits. The nifH gene, encoding a subunit of the nitrogenase enzyme which carries out nitrogen fixation, was present in 7 of 8 representative DNA samples. There were no consistent differences in nifH gene presence between pit or grassbed in this limited assessment. UAV surveys were conducted to scale the effects of stingray bioturbation on sediment biogeochemistry. Video imaging and aerial footage were used to identify stingray species and the numbers of pits in H. wrightii and unvegetated sand flats. Three to eight times as many pits were observed in bare areas outside of the seagrass beds than in seagrass beds. Dasyatis americana and Dasyatis sabina were observed in August and November. Larger bioturbators such as stingrays are powerful excavators, and this is one of the few studies to examine their effects on sediment biogeochemistry and microbes.
Details
- Title
- Sediment Biogeochemistry Response to Stingray Bioturbation in Halodule Wrightii
- Resource Type
- Thesis
- Contributors
- Jane M Caffrey (Advisor)Lisa A Waidner (Committee Member)Kenneth L Heck (Committee Member)
- Publisher
- University of West Florida Libraries
- Format
- pdf
- Number of pages
- 78
- Copyright
- © 2007 Carrie Shannon Tomlinson Stevenson
- Identifiers
- 99380092596806600
- Academic Unit
- Biology; Hal Marcus College of Science and Engineering
- Language
- English
- Awarding Institution
- University of West Florida; Master of Science (MS)
- Theses and Dissertations
- Master of Science (MS), University of West Florida