The complete disappearance of a long standing sacoglossan sea slug population following Hurricane Irma, despite recovery of the local algal community


Hurricanes often have large impacts on shallow marine ecosystems and the organisms living within. Here we document the impact of hurricane Irma to a long-standing population of sacoglossan sea slugs in the Florida Keys, USA. For many decades, researchers have been studying a population of clarki ecotype Elysia crispata at a borrow pit (limestone excavation) on Crawl Key, FL. This sea slug has been of interest due to an unusual relationship with its food algae termed kleptoplasty, where the slug sequesters chloroplasts taken from the food algae inside of its own cells and uses them for photosynthesis. Following Hurricane Irma, multiple intensive searches failed to find any E. crispata. This population, which at one point numbered in the thousands, has now been completely eliminated from this habitat for over two years following the hurricane. However, the algal population which previously sustained these slugs has fully recovered. Although this habitat now appears to be ideal for these slugs in terms of food availability, they have failed to recolonize. The reasons for this are unclear, but are likely due to the very short dispersal larval stage in this species. The loss of this population is unfortunate as it was the one best studied populations of photosynthetic sea slugs.

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We thank Kourtney Barber, Daniela Gutierrez, Allie Nockengost, and Evan Daly for assistance in the field surveys. We thank John Ambrosio for assistance with quadrat construction and survey training exercises. This research was supported by a University of Tampa Research Innovation and Scholarly Excellence/David Delo Research Grant Awarded to MLM and a private donor, who wishes to remain anonymous, who provided support to SKP.

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Correspondence to M. L. Middlebrooks.

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Middlebrooks, M.L., Curtis, N.E. & Pierce, S.K. The complete disappearance of a long standing sacoglossan sea slug population following Hurricane Irma, despite recovery of the local algal community. Symbiosis 80, 231–237 (2020).

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  • Hurricane Irma
  • Florida Keys
  • Sacolossa
  • Elysia crispata
  • Clarki
  • Population loss