Graduation Year

2025

Document Type

Thesis

Degree

M.S.

Degree Name

Master of Science (M.S.)

Degree Granting Department

Marine Science

Major Professor

Brad Seibel, Ph.D.

Co-Major Professor

Heather Judkins, Ph.D.

Committee Member

Philip Gravinese, Ph.D.

Keywords

endotoxin testing, Limulus amebocyte lysate (LAL), Pc, recovery, respirometry

Abstract

The horseshoe crab, Limulus polyphemus, inhabits shallow bays and estuaries where it encounters variable oxygen levels. Moreover, each year, the biomedical industry harvests hemolymph from hundreds of thousands of horseshoe crabs to use in bacterial contamination testing, yet the effects of bloodletting on their physiology are relatively unknown. This study aims to determine the oxygen supply capacity of Limulus polyphemus in relation to environmental hypoxia and biomedical bloodletting. Study animals were collected from the intertidal waters of Tampa Bay, Florida. Experiments included a control group that did not undergo substantial blood-volume reduction and a treatment group from which 10% of their total calculated hemolymph volume was drawn. The oxygen supply capacity and routine metabolic rate of each horseshoe crab were measured immediately after bloodletting and again two weeks later to determine whether a recovery of oxygen supply capacity or routine metabolic rate occurred. There was a significant difference in oxygen supply capacity amongst individuals based on mass. There was no significant effect of a 10% total hemolymph volume reduction on oxygen supply capacity. There was no significant difference in routine metabolic rate based on mass or hemolymph volume reduction. There was a positive correlation between oxygen supply capacity and routine metabolic rate in both the control and treatment groups. The results of this study may imply some ability for Limulus polyphemus to either buffer or recover from a minimal 10% bloodletting process, however, the process likely causes much stress, and the declining populations of horseshoe crabs may suggest that the biomedical processing these animals typically undergo is not sustainable.

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