Abstract

Hemolymph gas parameters of black sea urchins (Tetrapygus niger) and red sea urchins (Loxechinus albus) from a marine reserve at Punta San Juan, Peru were evaluated using a point of care analyzer (iSTAT). Physical examination, weight, diameter, and hemolymph data were obtained. Urchins were sampled either prior to removal from their natural aquatic environment (method 1) or after transport to an artificial environment (tank) without oxygen supplementation (method 2). Twenty-five black sea urchins and 18 red sea urchins were sampled using method 1 in the summer; 17 black sea urchins were sampled using method 2 during the winter season of the same year. Reference ranges were defined for weight, diameter, hemolymph appearance, turbidity, PCV, total solids, pH, pCO₂, pO₂, BE, HCO₃, TCO₂ and sO₂. A linear regression model was constructed for pO₂, pCO₂, and pH including variables determined using method 1. pO₂ was positively associated with pH, species (black sea urchin), HCO₃, and width and negatively associated with sO₂, BE, and weight. pCO₂ was positively associated with sO₂, species (red sea urchin), BE, and weight and negatively associated with pH and HCO₃. pH was positively associated with HCO₃ and sO₂ and negatively associated with pCO₂, TCO₂, PCV, and BE. Black sea urchin weight, TS, pH, pCO₂, pO₂, BE, HCO₃, and sO₂ were significantly different between methods. Hemolymph parameters that were significantly different between species using method 1 were pH, pCO₂, BE, and HCO₃. This study suggests point of care analyzers may be useful for evaluation of hemolymph gasses in red and black sea urchins.