First description of the life cycle of the jellyfish Rhizostoma luteum (Scyphozoa: Rhizostomeae)

Abstract

Jellyfish blooms are a significant environmental problem that is increasing and may be influenced by anthropocentric practices such as overfishing, pollution, eutrophication, translocation, climate change, and ocean acidification. Many jellyfish have unknown life cycles leading to these blooms. We describe for the first time, the life cycle of scyphozoan jellyfish Rhizostoma luteum from the planula to the young medusa stages, based on laboratory observations. We also provide a preliminary assessment of temperature related to life stages. Comparisons were made with early life history stages of its sibling species Rhizostoma pulmo and Rhizostoma octopus. The life cycle of R. luteum follows the general pattern of metagenesis of scyphozoans. Scyphistoma culture was maintained in filtered seawater at 17–17.5 °C, salinity 37 and light photoperiod (12:12 h light:dark). Scyphistomae were exposed to an experimental temperature descent for two days to test their survival capacity under severe winter conditions. Only one asexual reproduction mode was observed, which is employed for propagation, consisting of podocyst formation with excystment, subsequent development of scyphistoma, strobilation and liberation of viable ephyra. The development of the ephyra to metaephyra was photodocumented, reaching the metaephyra stage in approximately 21–25 days. Young medusae grow rapidly and maturity was reached after a 3-month post-liberation period with a mean bell diameter of 13.27 ± 2.26 cm and wet weight of 181.53 ± 53 g. The life cycle of R. luteum resembles that of its congeners, with the distinction that it has the unique features of being a brooding species (internal fertilisation with subsequent release of planulae) and under the conditions tested, the predominantly strobilation type observed was monodisc, and not polydisc as with the other two species in the genus Rhizostoma. As R. luteum shows sufficient requisite to form blooms if environmental circumstances change, it is important to understand its life cycle.

The Large Jellyfish Rhizostoma luteum as Sustainable a Resource for Antioxidant Properties, Nutraceutical Value and Biomedical Applications

“…The specimens used are young medusae, with an age range from about 23–140 days ( Table 1 ), with a proportionally increasing biomass with jellyfish age. The relation between fresh weight and diameter in Rhizostoma luteum has been described by [ 29 ], while the relationship between fresh weight (FW) and dry weight (DW) is documented for the first time for this species. The variability of the biometric measures, including the FW, the FW:diameter ratio and DW percentage values, is representative of the different growth stages of the jellyfish [ 30 ].…”

“…Specimens of Rhizostoma luteum jellyfish were reared in the laboratory (ICMAN-CSIC) from polyps. The origin of this living collection is from planulae gathered directly from the gonad of a free-swimming female medusa offshore of the coast of the Alboran Sea (Spain) in October 2015 (details in Kienberger et al [ 29 ]). For the present study, a total of 303 specimens were used.…”

“…The purpose of the work is to describe the organic compounds for Rhizostoma luteum for the first time, with the hypothesis that it can be a candidate for the isolation and production of bioactive compounds in several fields of food, cosmetics, and biomedical industries. This hypothesis is based on three facts inherent to this jellyfish species: (1) it is from the family of the Rhizostomaes , which is the family of jellyfish preferable for consumption in Asiatic cuisine [ 28 ]; (2) The natural adult size of this jellyfish is very large, reaching more than 60 cm in umbrella size, weighing 13 kg and having 3 m tentacles [ 26 , 27 , 29 ], making one of the largest species of this family and therefore converting each individual into considerable amount of biomass; and (3) its life cycle has been recently described and closed entirely in captivity [ 29 ], which is a very difficult achievement since it is an open-ocean species. These three facts suggest that, in the case the potential use of Rhizostoma luteum , the exploitation of this species’ biomass can be obtained both from the natural environment and from controlled culture in captivity.…”

“…The results presented here suggest this jellyfish to be a promising sustainable source for the production of several natural products. Rhizostoma luteum appears all year around on the coasts of the east Atlantic Ocean and Alboran Sea [ 29 ], providing a highly unexploited biomass. Now a positive association of this giant jellyfish species and an isolation of its bioactive compounds can be established.…”

Intervention Options to Accelerate Ecosystem Recovery From Coastal Eutrophication

“…Warming affects the oxygen budget of coastal ecosystems through increased stratification and elevated respiratory demands (Steckbauer et al, 2011), and compounds with global trends toward ocean de-oxygenation to increase the likelihood of coastal hypoxia (Breitburg et al, 2018). Likewise, vertically segregated primary production in upper layers and remineralization in bottom layers of stratified eutrophic coastal waters lead to elevated CO 2 in the bottom layer, which compounds with the trend toward elevated CO 2 resulting from ocean uptake of anthropogenic CO 2 released to the atmosphere (Borges and Gypens, 2010;Cai et al, 2011;Wallace et al, 2014). These combined trends render eutrophic coastal ecosystems more vulnerable to acidification.…”