LAUSR

Abstract: Although the evaluation of hematologic and biochemical parameters is a well-established diagnostic tool in vertebrate medicine, comprehensive understanding of these parameters in invertebrate species is lacking. This study provides baseline hemocyte concentrations and biochemistry values for a population of managed Japanese spider crabs (JSC; Macrocheira kaempferi) housed at six different public aquariums. The methodology for obtaining diagnostic hemolymph samples is described. Distinct hemocyte types were identified, including hyaline cells, semigranulocytes, and granulocytes, with hyaline cells as the predominant type. Correlates to exam findings and environmental parameters were evaluated and included higher absolute semigranulocyte counts (r = 0.65, P = 0.020) and triglyceride levels (r = 0.44, P = 0.014) in JSC with exoskeletal lesions; higher total protein (mean = 5.93 g/dl, P = 0.028), cholesterol (median = 18.5 mg/dl, P = 0.018), triglyceride (median = 15.5 mg/dl, P = 0.002), and amylase (median = 243 U/L, P = 0.013) in nonmolting JSC compared with JSC that have previously molted since acquisition (total protein mean = 4.83 g/dl, cholesterol median = 14 mg/dl, triglyceride median = 6.4 mg/dl, and amylase median = 131 U/L); and lower relative and absolute granulocyte counts (mean = 8.83% P = 0.030, median = 1,162 cells/µl P = 0.006, respectively) and higher albumin (median = 1.35 g/dl, P = 0.031) in JSC housed at facilities that used ozone sterilization. The data presented serve as a foundation for understanding basic clinical parameters in JSC hemolymph, as well as the potential influence of environmental stressors on those parameters.