Date of Award
5-2025
Rights
© 2025 Harrison D. Stern
Document Type
Thesis
Degree Name
Master of Science in Marine Sciences
Department
Marine Science
First Advisor
Markus Frederich
Second Advisor
Carrie Byron
Third Advisor
Alicia Williams
Abstract
Environmental DNA (eDNA) is a biomolecule that is found in the environment and comes from sloughed cells, fecal matter, gametes, and more. Recently, a hypothesis has been proposed that establishes a link between the external morphology of an organism and the amount of eDNA shed off into the environment. This hypothesis centers around the idea that species with softer morphology (squishy) shed more eDNA and species with harder morphology (crunchy) shed less, and has been coined the Squishy Crunchy Hypothesis. This study aimed to not only test this hypothesis on the Strongylocentrotus droebachiensis (Green Sea Urchin) but also assess the feasibility of using eDNA analysis techniques for S. droebachiensis, what affects eDNA shedding rates, along with testing eDNA analysis for S. droebachiensis in situ. Lab experiments determined the shedding rate using sterile buckets, with 1, 3, and 5 urchins. Metabolic tests were done using closed vessel respirometry to determine the effect of metabolic rate on eDNA shedding. Field tests included a 3.5-year sampling project and an in situ experiment placing urchins in a tidepool. qPCR was used to quantify the amount of eDNA in the biomass shedding and field samples. Significant trends were observed at higher temperatures (>13˚C) in the lab. S. droebachiensis was determined to be in the middle of the squishy-crunchy spectrum, according to the Squishy Crunchy Hypothesis, with better success predicted when targeting larger aggregations or larval urchins. While limited numbers of adults could be detected in the lab, they were unable to be detected well in the field, making the use of eDNA analysis on S. droebachiensis not viable in situ. Metabolic rate was also found not to influence eDNA shedding rates in S. droebachiensis. This research demonstrates that more investigation is needed to understand the potential use of eDNA in the phylum Echinodermata, as well as to do similar specific experiments on organisms for which eDNA analysis could prove useful.
Preferred Citation
Stern, Harrison D., "Investigating Biomass-Dependent DNA Shedding And The Squishy Crunchy Hypothesis In Green Sea Urchins (Strongylocentrotus droebachiensis)" (2025). All Theses And Dissertations. 447.
https://dune.une.edu/theses/447
Comments
Master's Thesis
Submitted to this repository and offered for educational purposes by its author under a CC BY-NC-ND 4.0 (Attribution-NonCommercial-NoDerivatives 4.0 International) deed.