California Sea Grant College Program

Withering syndrome (WS) is a disease of wild and cultured abalone, caused by aRickettsiales-like prokaryote (WS-RLP). While WS has decimated black abalone populationsthroughout most of California, both wild and cultured red abalone have shown resilience incertain environmental conditions. The changes in seawater temperature and food availabilityassociated with El Niño events may, however, stimulate the pathogenesis of WS in WS-RLP-infected red abalone. This study sought to examine the relative contributions and synergisticeffects of multiple stressors on development of WS, and establish sensitive and robust markersfor characterizing the sequential pathological changes associated with disease progression. This information is critical for the proper management of WS by both private aquaculturists and stateresource managers.