Crabs as biomonitoring tools: Development of non-lethal techniques for hemolymph and urine collection to assess ecosystem health.

Traditional sampling methods in crabs often require invasive procedures or euthanasia, limiting their use in long-term and conservation-sensitive studies. This work aimed to develop and validate a non-lethal protocol for collecting hemolymph and urine from estuarine crab species. Sixty adult crabs of Ucides cordatus and Cardisoma guanhumi were assigned to four groups for fluid collection. Specimens were anesthetized using MS-222 (tricaine methanesulfonate) with water cooled prior to sampling. Hemolymph was obtained from the base of the last pereopod, while urine was collected from the bladder using a refined anatomical approach. Survival rates were high, reaching 100 % in hemolymph groups and exceeding 80 % in urine groups. The protocol proved effective for safely obtaining biological fluids without compromising animal viability. This method represents a practical advance for non-lethal studies in ecotoxicology and crustacean physiology, particularly in tropical coastal ecosystems.