The Use of Cytology as an Adjunct Tool in the Health Assessment of the Long-Spined Sea Urchin, Diadema antillarum
Abstract
The long-spined sea urchin, Diadema antillarum, is recognized as a keystone invertebrate species of “greatest conservation need” by the Florida Fish and Wildlife Conservation Commission (FWC) because it is crucial in the maintenance of healthy coral reefs in the Caribbean, including the Florida Keys.1-3 Following a mass mortality event of D. antillarum in the early 1980s, the population has still not recovered.4,5 This event is one of the factors contributing to coral reef degradation with detrimental consequences for the ecosystem.5,6 Understanding health and disease in this ecologically important species is crucial in restoration efforts involving release of aquacultured or translocated animals.7 The objective of this study was to investigate the use of cytology in free-ranging D. antillarum collected in the Florida Keys as part of a larger scale health assessment protocol. Coelomic fluid and feces from fifty-seven sea urchins were collected using non-lethal techniques. Coelomic fluid cytology was useful to characterize the mononuclear cell population of the coelomic cavity, including mononuclear phagocytes (aka amoebocytes) and spherule cells, both with variable phagocytic activity. There were also salt crystals and variable numbers of spermatozoa in different stages of maturation. Four of 57 coelomic fluid samples contained accidental intestinal aspiration. Fecal cytology contained plant material, diatoms, and various crystals in all samples. There were protozoa (n=14), ciliates (n=11), flagellates (n=1), and protozoa with morphology suggestive of amoeba (n=8). Cytology provided useful diagnostic baseline information regarding the characterization of coelomic and fecal samples of free-ranging D. antillarum. This information was helpful for guidance in selecting additional diagnostic testing and, thus, expansion of the health assessment protocol.
Acknowledgements
The project was supported by the Florida Fish and Wildlife Conservation Commission program, Florida’s Wildlife Legacy initiative (State Wildlife Grants CFDA No. 15.634) and the United States Fish and Wildlife Service grants program, Marine Projects Grant Cycle 2013 T-37 (federal award No. T-F14AF00891).
* Presenting author
+ Student presenter
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