AUTHOR=Frolova Alexandra , Miglietta Maria Pia 

TITLE=Insights on Bloom Forming Jellyfish (Class: Scyphozoa) in the Gulf of Mexico: Environmental Tolerance Ranges and Limits Suggest Differences in Habitat Preference and Resistance to Climate Change Among Congeners

JOURNAL=Frontiers in Marine Science

VOLUME=7

YEAR=2020

URL=https://www.frontiersin.org/journals/marine-science/articles/10.3389/fmars.2020.00093

DOI=10.3389/fmars.2020.00093

ISSN=2296-7745

ABSTRACT=<p>Jellyfish are important components of marine food webs and form problematic blooms that negatively impact human enterprise. Jellyfish of the genus <italic>Aurelia</italic> (Class Scyphozoa) are common bloom-formers in the Gulf of Mexico (GoM). <italic>Aurelia</italic> have a multi-modal life cycle where the perennial polyp produces seasonal medusae. Abiotic tolerance ranges and limits strongly influence the distribution of marine species but are unknown for most jellyfish species. Tolerance limits for survival are crucial to understanding present polyp distribution and how distribution may change in climate change scenarios. We sampled and barcoded two <italic>Aurelia</italic> species from the GoM, namely <italic>Aurelia</italic> sp. 9 and a possible new species found offshore (<italic>Aurelia</italic> sp. new). Planulae obtained from one medusa of <italic>Aurelia</italic> sp. new, and five medusae of <italic>Aurelia</italic> sp. 9 were used to establish laboratory cultures. Polyps of <italic>Aurelia coerulea</italic>, a species native to Japan but introduced in North America, Australia, and Europe, were obtained from a local aquarium, barcoded, and used to establish laboratory cultures. Using controlled laboratory experiments, we determined the temperature and salinity limits for polyp survival of the two GoM species and <italic>A. coerulea</italic>. We find that <italic>A.</italic> sp. 9 and <italic>A. coerulea</italic> were tolerant of a broad range of temperatures and salinities, but differed in tolerance limits, suggesting potential differences in habitat and resistance to climate change. <italic>A.</italic> sp. 9 was most tolerant of high temperatures and low salinities, such as those found in the estuaries of the GoM. Summer high temperatures in the coastal GoM exceed the upper thermal tolerance limit of <italic>A.</italic> sp. new and <italic>A. coerulea</italic>, suggesting that <italic>A</italic>. sp. new is an offshore species and that the coastal GoM waters may not be a suitable environment for <italic>A. coerulea</italic>. Based on the upper thermal limits identified in this study, the 4°C ocean temperature increase projected for the GoM by the next century may negatively impact <italic>Aurelia</italic> sp. 9 and <italic>Aurelia</italic> sp. new populations and is expected to deter <italic>A. coerulea</italic> from invading the GoM. This is the first account of <italic>Aurelia</italic> sp. new and the first report of temperature and salinity ranges and tolerance limits for <italic>Aurelia</italic> species.</p>