A Comparison of Stress Susceptibility of Sea Urchins and Sea Cucumbers in Aquaculture Conditions

Abstract

Purple sea urchins and giant California sea cucumbers are becoming increasingly important sources of food and marine pharmaceuticals. Because there have been many fisheries established to harvest these species, many of them have been greatly depleted. In order to alleviate this problem intensive aquaculture is generating interest as a solution. However, when an animal is placed into an artificial system, there are a variety of stresses that it can encounter, such as salinity changes or handling. In order to determine which species is more susceptible to stress, various physiological and immunological assays were done on the coelomic fluid of purple sea urchins, Strongylocentrotus purpuratus and giant California sea cucumbers, Parastichopus californicus. Assays included total and phagocytic cell counts, phagocytic capacity, and lytic activity. Our results indicated that low salinity and handling both cause significant stress responses in sea urchins. For sea cucumbers, there were few significant differences from the control, and no differences in immune function. These results indicate that in an aquaculture environment the purple sea urchin is more likely to be stressed compared to the giant California sea cucumber, and that facilities interested in raising sea urchins should be particularly careful to avoid any condition that is potentially stressful.