Effects of temperature and salinity on four species of northeastern Atlantic scyphistomae (Cnidaria: Scyphozoa)

Abstract

Laboratory incubation experiments were conducted to examine the effects of different temperatures (4, 9, 14, 19, 23°C) and salinities (21, 27, and 34) on survival and asexual reproduction of scyphistomae of Cyanea capillata, Cyanea lamarckii, Chrysaora hysoscella, and Aurelia aurita in order to better understand how climate variability may affect the timing and magnitude of jellyfish blooms. Significant mortality was only observed for C. capillata and Ch. hysoscella at the highest and lowest temperatures respectively, but temperature and salinity significantly affected the asexual reproductive output for all species. As temperature increased production rates of podocysts increased and, if produced, progeny scyphistomae by side budding also increased. However, strobilation rates, and therefore the mean number of ephyrae produced, decreased when scyphistomae were exposed to elevated temperatures. These results provide a mechanistic explanation for why ephyrae of these species tend to be produced during colder periods of the year whilst summer and early autumn are probably important periods for increasing the numbers of scyphistomae in natural populations.

Dynamics and asexual reproduction of the jellyfish Aurelia coerulea benthic life stage in the Thau lagoon (northwestern Mediterranean)

“…So far, no clear negative effect of salinity was ever found on Aurelia spp. scyphistoma survival (Willcox et al 2007;Holst and Jarms 2010;Widmer et al 2016) nor somatic growth (Willcox et al 2007;Hubot et al 2017), except when reaching freshwater conditions (Holst and Jarms 2010). However, most laboratory studies so far, focused on the influence of fresh water inputs (e.g.…”

The ICES Working Group on Oceanic Hydrography: A Bridge From In-situ Sampling to the Remote Autonomous Observation Era

“…While most science emerging from the observational systems that feed the IROC are performed independently by WGOH members within their science groups, collaborative studies have also emerged (e.g., Holliday et al, 2008;Holt et al, 2012;Hughes et al, 2012;Mork et al, 2014). Besides science, most outreach is achieved through the production of the IROC, currently used as a quick guide to environmental conditions for assessments and in support of other scientific studies (e.g., Nøttestad et al, 2015;Punzón et al, 2016;Widmer et al, 2016;Townhill et al, 2017;Brander, 2018). To continue the success of the IROC, the WGOH is continually seeking new ways to engage with a burgeoning global ocean observing community and to distinguish the IROC in an increasingly crowded field of ocean status reports.…”

Shorter, warmer winters may inhibit production of ephyrae in a population of the moon jellyfish Aurelia aurita

“…Any offspring (podocysts, directly and stolonally budded polyps or ephyrae) produced before the start of the experiment were removed using a scalpel and Pasteur pipette after naturally separating from the parent polyp. Over 7 days (sensu Widmer et al, 2016;Treible & Condon, 2019) replicates were transitioned to experimental temperatures (4°C, 1.5°C day -1 ; 7°C, 1.1°C day -1 ; 10°C, 0.7°C day -1 ; and 13°C, 0.2°C day -1 ).…”

“…polyps strobilated earlier when the pre-strobilation temperature was higher. However, a number of other studies propose that a period at colder temperatures is necessary to ensure that ephyral growth and development occurs in spring, when temperate species can take advantage of the spring bloom (Lucas, 2001;Widmer et al, 2016).…”