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

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.

Multiple reproduction forms in the polyps of the cannonball jellyfishStomolophussp. 2: Probable life‐cycle reversal

“…Podocysts are known to protect the species for survival in periods of low food availability and stress conditions (Arai, 2008; Schiariti et al, 2014). In fact, podocysts are an adaptive dispersion mechanism of jellyfish, and the key element to ensuring species survival facing changing environmental conditions, such as the current global warming period (Enrique‐Navarro et al, 2021; Klein et al, 2014; Knowles, 2012). Thus, future research must be focused on evaluating responses in podocyst production to environmental changing conditions, such as temperature increase, oxygen decrease, and ocean acidification (Dong et al, 2015; Enrique‐Navarro et al, 2021; Ikeda et al, 2011; Jiang et al, 1993; Lucas et al, 2012; Nevarez‐Lopez et al, 2020).…”

“…In fact, podocysts are an adaptive dispersion mechanism of jellyfish, and the key element to ensuring species survival facing changing environmental conditions, such as the current global warming period (Enrique‐Navarro et al, 2021; Klein et al, 2014; Knowles, 2012). Thus, future research must be focused on evaluating responses in podocyst production to environmental changing conditions, such as temperature increase, oxygen decrease, and ocean acidification (Dong et al, 2015; Enrique‐Navarro et al, 2021; Ikeda et al, 2011; Jiang et al, 1993; Lucas et al, 2012; Nevarez‐Lopez et al, 2020). All of these conditions have been forecasted for the Gulf of California by the year 2100 (Ayala‐Bocos et al, 2016; Herrera, 2020; López‐Martínez et al, 2017; Saldívar‐Lucio et al, 2015).…”

“…Podocysts are known to protect the species for survival in periods of low food availability and stress conditions (Arai, 2008;Schiariti et al, 2014). In fact, podocysts are an adaptive dispersion mechanism of jellyfish, and the key element to ensuring species survival facing changing environmental conditions, such as the current global warming period (Enrique-Navarro et al, 2021;Klein et al, 2014;Knowles, 2012).…”

“…Thus, future research must be focused on evaluating responses in podocyst production to environmental changing conditions, such as temperature increase, oxygen decrease, and ocean acidification (Dong et al, 2015;Enrique-Navarro et al, 2021;Ikeda et al, 2011;Jiang et al, 1993;Lucas et al, 2012;Nevarez-Lopez et al, 2020). All of these conditions have been forecasted for the Gulf of California by the year 2100 (Ayala-Bocos et al, 2016;Herrera, 2020;López-Martínez et al, 2017;Saldívar-Lucio et al, 2015).…”

Hanging under the ledge: synergistic consequences of UVA and UVB radiation on scyphozoan polyp reproduction and health

“…However, sensitivity to UVR varies by taxa, with cnidarians, including scyphozoan jellyfish, showing lesser sensitivity to changes in UVB than other organisms ( Llabrés et al, 2013 ). Across systems, scyphozoan jellyfish have shown resilience to a variety of environmental stressors ( Richardson et al, 2009 ), including warming ocean temperatures ( Purcell, 2007 ; Purcell, Hoover & Schwarck, 2009 ), coastal acidification ( Winans & Purcell, 2010 ; Enrique-Navarro et al, 2021 ), increased occurrences of hypoxia ( Condon, Decker & Purcell, 2001 ; Grove & Breitburg, 2005 ; Thuesen et al, 2005 ; Miller & Graham, 2012 ), as well as combinations of acidification and hypoxia ( Treible et al, 2018 ). Their resilience has been used as one explanation for the apparent increase in jellyfish blooms in many coastal waters around the globe ( Richardson et al, 2009 ).…”