Impact of ocean warming and ocean acidification on asexual reproduction and statolith formation of the symbiotic jellyfish Cotylorhiza tuberculata

PLoS One. 2021 Aug 4;16(8):e0254983. doi: 10.1371/journal.pone.0254983. eCollection 2021.

Abstract

Ocean acidification and warming are challenging marine organisms and ecosystems around the world. The synergetic effects of these two climate change stressors on jellyfish remain still understudied. Here, we examine the independent and combined effects of these two environmental variables on polyp population dynamics of the Mediterranean jellyfish Cotylorhiza tuberculata. An experiment was conducted to examine asexual reproduction by budding and strobilation considering current and ca. 2100 winter (Trial 1, 36 days) and summer (Trial 2, 36 days) conditions under the RCP8.5 (IPCC 2013). In Trial 1, a temperature of 18°C and two pH levels (current: 7.9 and, reduced: 7.7) were tested. Trial 2 considered two temperature levels 24°C and 30°C, under current and reduced acidification conditions (8.0 and 7.7, respectively). Ephyrae size and statolith formation of released ephyrae from polyps exposed to summer temperatures under both acidification treatment was also analyzed. Zooxanthellae density inside the polyps throughout the experiment was measured. C. tuberculata polyps could cope with the conditions mimicked in all experimental treatments and no significant effect of pH, temperature, or the combination of both variables on the abundance of polyps was observed. At 18°C, strobilation was reduced under high PCO2 conditions. Under summer treatments (24°C and 30°C), percentage strobilation was very low and several released ephyrae suffered malformations and reduced size, as a consequence of reduced pH and elevated temperatures, separately. The number of statoliths was not affected by pH or temperature, however, bigger statoliths were formed at elevated temperatures (30°C). Finally, zooxanthellae density was not affected by experimental conditions, even if, the duration of the experiment significantly affected symbiont concentration. Our results show that even though polyps of C. tuberculata would thrive the future worst scenario predicted for the Mediterranean Sea, their capacity to undergo a proper strobilation and to produce healthy ephyrae will be more vulnerable to climate induced environmental conditions, thereby affecting medusae recruitment and, therefore, population dynamics of the species.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Acids / chemistry*
  • Alkalies / chemistry
  • Animals
  • Carbon Dioxide / analysis
  • Climate Change*
  • Linear Models
  • Oceans and Seas*
  • Oxygen / analysis
  • Reproduction, Asexual / physiology*
  • Scyphozoa / physiology*
  • Symbiosis / physiology*
  • Temperature

Substances

  • Acids
  • Alkalies
  • Carbon Dioxide
  • Oxygen

Grants and funding

This work was funded by the Spanish Ministerio de Ciencia, Innovación y Universidades (https://www.ciencia.gob.es) under grant number CTM2016-75487-R for the project MED2CA. AEN was financially sustained by a Ph.D. fellowship from the MED2CA project (https://med2ca.csic.es). This work is a contribution to the CSIC interdisciplinary thematic platform, WATER:iOS and the Project Agreement "Sistema de Observación y Predicción de Medusas en el Mar Balear” among Govern des Illes Balears, SOCIB and CSIC.