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ORIGINAL RESEARCH article

Front. Mar. Sci.
Sec. Marine Biology
doi: 10.3389/fmars.2022.1031977
This article is part of the Research Topic

Integration of Development, Physiology and Responses to Environmental Change in Aquatic Invertebrates

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Aerobic respiration, biochemical composition, and glycolytic responses to ultraviolet radiation in jellyfish Cassiopea sp

Samir M. Aljbour1*, Ricardo N. Alves1 and Susana Agusti1
  • 1Red Sea Research Center, King Abdullah University of Science and Technology, Saudi Arabia
Provisionally accepted:
The final, formatted version of the article will be published soon.

The light-dependent zooxanthellate jellyfish Cassiopea sp. (the upside-down jellyfish) is invasive/exotic in many shallow and clear marine habitats, where the jellyfish might be exposed to high levels of ultraviolet radiation (UVR). Compared to other reef organisms, the sensitivity/resilience of the semi-transparent jellyfish to UVR exposure is overlooked. Therefore, we experimentally investigated the metabolic and physiological responses of Cassiopea sp. from the Red Sea to natural levels of underwater UVR following 16 days of exposure to three light treatments: 1) control group with only photosynthetically active radiation (PAR), 2) PAR+UV-B, and 3) PAR+UV-B+UV-A. While jellyfish body mass increased (by 40%) significantly in the control group, it did not increase in either of the UV treatments. However, both UV-exposed jellyfish had higher (98% to 120%) mitochondrial electron transport system (ETS) activity than the control group. Therefore, the results indicate elevated aerobic respiration rates in UV-exposed jellyfish (i.e., reflecting a higher energy cost of UVR exposure). Neither the lactate dehydrogenase (LDH) activity nor the available energy (Ea) exhibited different levels among UVR treatments compared to the control group. In contrast, pyruvate kinase activity was significantly lower (by 46%) in all UV-exposed jellyfish compared to the control group. Unchanged Ea and LDH activity combined with higher ETS activity indicates a high aerobic capacity of jellyfish, which might explain their ability to cope with UVR exposure-induced higher energy demands without inducing the onset of anaerobiosis. The results indicated that UV-A does not amplify or modulate jellyfish physiology and growth under UV-B exposure. In conclusion, the findings suggest that the jellyfish is more resilient (i.e., in terms of survival) to UVR than other cnidarians. This study on Cassiopea is the first to address its metabolic and physiological responses to UVR. Therefore, it could be used as a framework for further studies aiming to better understand jellyfish physiology.

Keywords: jellyfish, Cassiopea sp., mitochondrial respiration, Pyruvate Kinase, Lactate dehydrogenase, Energy allocation, Medusae, anaerobic respiration

Received:30 Aug 2022; Accepted: 14 Dec 2022.

Copyright: © 2022 Aljbour, Alves and Agusti. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

* Correspondence: Dr. Samir M. Aljbour, Red Sea Research Center, King Abdullah University of Science and Technology, Thuwal, Saudi Arabia