Evaluating in situ Grazing Patterns of Lytechinus variegatus and their Effects on Seagrass Beds of Thalassia testudinum

<p>The sea urchin<em> Lytechinus variegatus </em>is a known grazer of the seagrass <em>Thalassia testudinum</em>, and has been known to denude vast stands of seagrass beds at high densities. Outside of these denudation events, the effects of sea urchins on seagrass are poorly understood. This study examines the effects of <em>L. variegatus</em> on <em>T. testudinum</em> in situ, to understand how sea urchins are affecting seagrasses <em>in situ</em>. Results indicate that urchins were found in the offshore portion of the seagrass bed at densities up to 4 urchins/m². Changes in temperature and sediment size in the bay indicate that there is a greater exchange rate bay water in the offshore portion of the seagrass bed, and bay water may act as a temperature buffer for urchins in that part of the bed. Urchin movement experiments and dispersion patterns indicate that urchins move more where seagrass cover is low. Field surveys and lab choice experiments indicate that urchins tend to be detrital consumers of seagrass blades rather than herbivores on live seagrass tissue. Together, these results suggest that <em>L. varieagtus</em> densities observed in this study do not appear to have strong negative affects on seagrass beds as has been previously seen in field enclosure experiments and denudation events.</p>

Name thesis:degree_name

Master of Science in Integrative Biology (MSIB)

Level thesis:degree_level

Thesis

Discipline thesis:degree_discipline

Biology

Year dc:date.available

2018

Author dc:creator

• Parson, Adrianna

Contributors dc:contributor

• Dr. Troy Mutchler
• Dr. William Ensign
• Dr. Jared Taglialatela

• Lytechinus Variegatus
• Thalassia Testudinum
• grazing
• seagrass
• sea urchin
• in situ
• Animal Studies
• Behavior and Ethology
• Biology
• Integrative Biology
• Marine Biology
• Population Biology
• Terrestrial and Aquatic Ecology

Repository record dc:identifier

https://digitalcommons.kennesaw.edu/integrbiol_etd/27

OAI identifier oai:identifier

oai:digitalcommons.kennesaw.edu:integrbiol_etd-1026