Ecology of Blooming Jellyfish in the Gulf of Mexico

Abstract

Jellyfish (Scyphozoa, Cnidaria) are important components of marine food webs and form problematic blooms that negatively impact humans, but are understudied in the Gulf of Mexico (GoM). Scyphozoans have a multi-modal lifecycle where the benthic polyp produces seasonal pelagic medusae. We used DNA barcoding and multigene phylogenetic analyses to present evidence of a new Aurelia species, Aurelia sp. 17, in the northern GoM. Using controlled laboratory experiments, we determined the temperature and salinity limits for polyp survival of two GoM species, Aurelia sp. 17 and Aurelia sp. 9, and Aurelia coerulea from Japan. Aurelia sp. 9 and Aurelia coerulea are tolerant of a broad range of temperatures and salinities but have different tolerance limits. The narrower thermal tolerance range of Aurelia sp. 17 suggests adaptation to thermally stable marine environments. To address the lack of knowledge on polyp distribution, we constructed habitat suitability maps for Aurelia sp. 9 and Aurelia sp. 17. GoM coastal waters are suitable for Aurelia sp. 9, but not Aurelia sp. 17, and water temperature, not salinity, limits the distribution of both species. While 94% of GoM artificial reefs and 97% of gas platforms are suitable for Aurelia sp. 9, only 37% of reefs and 40% of gas platforms have conditions suitable for Aurelia sp. 17. Summer-high water temperatures restrict Aurelia sp. 17 polyps to deeper offshore waters. To identify trends, bloom events, seasonal and spatial timing in presence for Aurelia spp., Stomolophus sp., and Chrysaora sp., we analyzed Texas Park and Wildlife Department’s trawl survey data from 1982 through 2018 across bay and GoM regions of the Texas coast. Interannual numbers of Aurelia spp. vary greatly, with multiple blooms recorded over the survey period in the GoM. Abundance of Chrysaora sp. in bays and the GoM was consistent across years, while Stomolophus sp. numbers have remained low since about 2006. Aurelia spp. were encountered with similar frequency in bays and the GoM, but CPUE was higher in the GoM. Interannual occurrence of Chrysaora sp. was similar among bay and GoM regions. This work advances our understanding of blooming jellyfish in the GoM.