Different Physiology in the Jellyfish Cassiopea xamachana and C. frondosa in Florida Bay
Abstract
The jellyfish Cassiopea xamachana and C. frondosa co-occur within some habitats in the Florida Keys, but the frequency with which this occurs is low. It is hypothesized that the symbiosis with different dinoflagellates in the Symbiodiniaceae is the reason: the medusae of C. xamachana contain heat-resistant Symbiodinium microadriaticum (ITS-type A1), whereas C. frondosa has heat-sensitive Breviolum sp. (ITS-type B19). Cohabitation occurs at depths of about 3–4 m in Florida Bay, where the water is on average 0.36 °C cooler, or up to 1.1 °C cooler per day. C. frondosa tends not to be found in the warmer and shallower (<2 m) depths of Florida Bay. While the density of symbionts is about equal in the small jellyfish of the two species, large C. frondosa medusae have a greater density of symbionts and appear darker in color compared to large C. xamachana. However, the number of symbionts per amebocyte are about the same, which implies that the large C. frondosa has more amebocytes than the large C. xamachana. The photosynthetic rate is similar in small medusae, but a greater reduction in photosynthesis is observed in the larger medusae of C. xamachana compared to those of C. frondosa. Medusae of C. xamachana have greater pulse rates than medusae of C. frondosa, suggestive of a greater metabolic demand. The differences in life history traits of the two species were also investigated to understand the factors that contribute to observed differences in habitat selection. The larvae of C. xamachana require lower concentrations of inducer to settle/metamorphose, and they readily settle on mangrove leaves, submerged rock, and sand compared to the larvae of C. frondosa. The asexual buds of C. xamachana are of a uniform and similar shape as compared to the variably sized and shaped buds of C. frondosa. The larger polyps of C. frondosa can have more than one attachment site compared to the single holdfast of C. xamachana. This appears to be an example of niche diversification that is likely influenced by the symbiont, with the ecological generalist and heat-resistant S. microadriaticum thriving in C. xamachana in a wider range of habitats as compared to the heat-sensitive symbiont Breviolum sp., which is only found in C. frondosa in the cooler and deeper waters.
Additional Information
© 2021 by the authors. This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. (This article belongs to the Special Issue The Future of Coral Reefs: Research Submitted to ICRS 2021/2, Bremen, Germany) Received: 4 September 2021 / Revised: 9 November 2021 / Accepted: 26 November 2021 / Published: 3 December 2021. We thank Rich Aronson, who took Figure 1A, and Henry Laird helped with Figure 2. This research received funding from the Key Largo Marine Research Laboratory and the University of Georgia. Author Contributions. Conceptualization, W.K.F., D.K.H., D.W.K. and A.H.O.; methodology, W.K.F., D.K.H., D.W.K. and A.H.O.; writing—original draft preparation, W.K.F.; writing—review and editing, W.K.F., D.K.H. and A.H.O. All authors have read and agreed to the published version of the manuscript. Data is available upon request. The authors declare no conflict of interest. Institutional Review Board Statement: Not applicable. Informed Consent Statement: Not applicable.Attached Files
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Additional details
- Eprint ID
- 112279
- Resolver ID
- CaltechAUTHORS:20211208-560024000
- Key Largo Marine Research Laboratory
- University of Georgia
- Created
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2021-12-10Created from EPrint's datestamp field
- Updated
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2022-02-01Created from EPrint's last_modified field