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Mass mortality of collector urchins Tripneustes gratilla in Hawai`i

February 2, 2023

As grazers, sea urchins are keystone species in tropical marine ecosystems, and their loss can have important ecological ramifications. Die-offs of urchins are frequently described, but their causes are often unclear, in part because systematic examinations of animal tissues at gross and microscopic level are not done. In some areas, urchins are being employed to control invasive marine algae. Here, we describe the pathology of a mortality event in Tripneustes gratilla in Hawai`i where urchins were translocated to control invasive algae. Although we did not determine the cause of the mortality event, our investigation indicates that animals died from inflammation of the test and epidermal ulceration, followed by inability to maintain coelomic fluid volume, colonization of coelomic fluid by opportunists (diatom, algae), and inappetence. Parasites, bacteria, fungi, and viruses were not evident as a primary cause of death. Pathology was suggestive of a toxin or other environmental cause such as lack of food, possibilities that could be pursued in future investigations. These findings highlight the need for caution and additional tools to better assess health when translocating marine invertebrates to ensure maximal biosecurity.

Publication Year 2023
Title Mass mortality of collector urchins Tripneustes gratilla in Hawai`i
DOI 10.3354/dao03716
Authors Thierry M. Work, Julie Dagenais, Robert Rameyer, Renee Breeden, Tina Weatherby
Publication Type Article
Publication Subtype Journal Article
Series Title Diseases of Aquatic Organisms
Index ID 70241047
Record Source USGS Publications Warehouse
USGS Organization National Wildlife Health Center