The Effect of Hemolymph Extraction Volume and Handling Stress on Horseshoe Crab Mortality

Abstract

We evaluated mortality associated with hemolymph extraction of 0, 10, 20, 30, and 40% of estimated hemolymph volume among low-stress and high-stress groups of horseshoe crabs. In addition to bleeding, the high-stress group underwent simulated transport and handling procedures associated with the biomedical industry’s bleeding process. Mortality rates of the unbled animals were not significantly different between the stressed and unstressed groups. Of the bled animals, there was a significantly higher mortality rate (8.3%) in the stressed group when compared to the unstressed group (0%), suggesting a possible synergistic effect between hemolymph extraction and external stressors. Within the stressed group, mortality was significantly associated with bleeding (P = 0.009). Within the stressed group, mortality was significantly associated with the amount of blood withdrawn (P = 0.009). Mortality rate ranged from 0 to 29.4% over the range of 10–40% hemolymph volume withdrawn. Insight was provided into the possible synergistic effect of blood extraction and external stressors associated with biomedical transport and holding methods on horseshoe crab mortality. Future strategies to reduce horseshoe crab mortality associated with biomedical bleeding must not only take into consideration the effects of bleeding but also the physiological stressors attributable to harvest, transport, and holding conditions.