Habitat suitability modeling of Aurelia jellyfish (Cnidaria, Scyphozoa) in the Gulf of Mexico suggests distinct species’ distributions based on tolerance limits

Abstract

Aurelia is a genus of scyphozoan jellyfish with cosmopolitan distribution and a propensity to form large aggregations, or “blooms.” Along the northern Gulf of Mexico (GoM) coast, blooms of Aurelia have caused problems for human enterprise. Mature Aurelia sp. 9 and sp. 18 medusae are observed each season, yet their benthic originators, the polyps, have never been found in nature in the GoM. The absence of information on polyp locations greatly limits our understanding of bloom formation, as we are unable to identify bloom origins or study medusae production in situ. To address the lack of knowledge on polyp distribution, suitable habitats, including natural and artificial settlement substrates for A. sp. 9 and A. sp. 18 were modeled using a GIS spatial analysis, utilizing previously published experimentally derived species’ tolerance ranges for temperature and salinity. Spatial models considered temperature and salinity parameters from surface down to 1500 m utilizing a ¼ degree grid size. The results suggest the GoM coastal waters have suitable environmental parameters for A. sp. 9 but not A. sp. 18 and that water temperature, but not salinity, limits the distribution of both species. Also, 94% of GoM artificial reefs and 97% of gas platforms fell within the modeled distribution range for A. sp. 9, compared to only 37% and 40% for A. sp. 18, respectively. Models suggest that A. sp. 18 may be an offshore species restricted to the deeper shelf waters of the GoM by summer-high water temperatures and that future increases in water temperature, such as those expected with climate change, may negatively impact Aurelia jellyfish populations in the northern GoM.