Physiological impacts of time in holding ponds, biomedical bleeding, and recovery on the Atlantic horseshoe crab, Limulus polyphemus

Abstract Atlantic horseshoe crabs, Limulus polyphemus (HSC), are commercially harvested along the eastern U.S. coast and bled for hemolymph used in pharmaceutical safety testing. In South Carolina, some HSCs are held in outdoor ponds before transport to facilities where they are bled and then released to the wild. This study tested whether the time HSCs are held before bleeding, bleeding itself, or the duration of the recovery after bleeding affects HSC mortality and physiological condition. Female HSCs were collected from Coffin Point Beach, South Carolina (April 22–24, 2016), held in ponds for 2, 4, 6 or 8 weeks, then bled or held as controls. Body weights, hemocyanin concentrations, and hemocyte densities were measured prior to treatment (bled/control) and at 2, 6 and 12 days of recovery. Hemocyanin concentrations declined significantly in HSCs held in ponds for 8 weeks prior to bleeding and were excluded from further analyses. Compared to some studies, HSC mortalities were low (11%). Impacts of time in holding ponds, bleeding, and recovery from bleeding on physiological measures were assessed using 3-way fixed-effects ANOVA. While duration of recovery had main effects on both physiological measures, significant interactions were also present. There was an interaction of treatment and recovery duration, with control crabs having higher hemocyte densities than bled animals at days 2 and 6 of recovery. Treatment, pond time, and recovery duration interacted to influence hemocyanin concentration. Our study suggests both main and synergistic effects are important when assessing the physiology and mortality of HSCs harvested for biomedical purposes.