Successful Culture of Pelagia noctiluca (Cnidaria: Scyphozoa) Over Time: A Continuous Supply of the Holoplanktonic Jellyfish for Research and Industrial Applications

Abstract

The scyphozoan Pelagia noctiluca has potential value for research and a wide variety of industrial applications. However, its holoplanktonic life cycle makes it difficult to maintain a permanent stock in aquaculture, unlike the continuous supply of newly-released ephyrae from jellyfish species with a benthic life stage. We investigated optimal feeding conditions for the captive breeding of P. noctiluca, monitoring total body diameter, morphological development, survival rate, and instantaneous growth rate. Diets of different items encapsulated in gelatin or non-motile prey were not suitable for successful growth of the early stages (ephyra and metaephyra), whereas rotifers were a sufficient food source for healthy growth. Fertilized eggs from sexually-mature jellyfish were obtained at 84.5 ± 2.1 and 87.0 ± 9.9 days post-fecundation in the presence and absence of gelatinous prey (Aurelia sp.), respectively. In contrast with the general consensus, we demonstrate that the incorporation of medusivorous prey was not essential for proper growth and closure of P. noctiluca life cycle. Instead, we recommend the inclusion of white shrimps (Acetes sp.) for the formation and maturation of gonads and production of eggs. Instantaneous growth rates (57.0% d-1), the highest reported to date for this species in captive conditions, were higher during the early stages. A third generation of cultured P. noctiluca was obtained for the first time (169 – 179 experimental days), demonstrating the durability of the culture, providing permanent stock and halving the production time of mature individuals compared to previous studies. Finally, we validated the use of captive-bred specimens through quantification of the hemolytic area after the sting process using the tentacle skin blood agarose assay methodology.

Versatile aquarium for jellyfish: A rearing system for the biomass production of early life stages in flow-through or closed systems

“…The rearing of P. noctiluca is a challenge for the scientific and aquarist community (Ramondenc et al, 2019;Ballesteros et al, 2022). Lilley et al (2014a) proposed a system composed of 5 to 15 L receptacles with motorized PVC paddles rotating to keep animals in suspension with recurrent water changes (Ramondenc et al, 2019, Figure 1A).…”

“…In addition, for the first time to our knowledge, P. noctiluca to be safely maintained during their early life stages in a flow-through system (Table 2). The design of the screen mesh (Figures 1B, D), has allowed fertilized eggs metamorphose into ephyrae in the aquarium directly (Figure 4) without staff having to move the transparent ephyrae between receptacles as in Purcell et al (2013), Lilley et al (2014a), Ramondenc et al (2019); Ballesteros et al (2021) and Ballesteros et al (2022). In disagreement with Purcell et al (2013) and Duarte et al (2021), we do not recommend the ephyrae grow-out of P. noctiluca in a flow-through system using conventional kreisels or rectangular tanks due to their risk of being retained on the mesh screen.…”

“…nauplii and Brachiounus spp. (rotifers) are frequently used for husbandry (Raskoff et al, 2003;Purcell et al, 2013;Crow et al, 2013;Duarte et al, 2021) but some researchers have highlighted the importance of prey size for proper rearing, particularly during the polyp and early planktonic life cycle stages (Widmer et al, 2005;Purcell et al, 2013;Miranda et al, 2016;Ballesteros et al, 2022). In our system, the interchangeable mesh screen (Figures 1B, D, 2D) allows adaptation of the size of the mesh to the size of the prey in the aquarium.…”

“…In our system, the interchangeable mesh screen (Figures 1B, D, 2D) allows adaptation of the size of the mesh to the size of the prey in the aquarium. For example, if the prey offered is Brachionus plicatilis (≈ 100 -200 µm)an ideal size range for capture and ingestion by polyps (Raskoff et al, 2003) and ephyrae such as Phyllorhiza punctata (Miranda et al, 2016) and P. noctiluca (Ballesteros et al, 2022) a mesh screen of 350 µm can be selected (Tables 1, 2). When Artemia sp.…”

“…With the aim of reducing the time required for maintenance routines, and exploring new technologies to scale jellyfish cultures and biomass production, we present a versatile modified kreisel aquarium that allows safe cultivation early jellyfish life stages in both flow-through and closed systems. Our prototype aquarium is an important contribution to jellyfish husbandry techniques, especially for P. noctiluca, a species whose culture represents a challenge for the scientific and aquarist community due to the lack of polyp stage in its life cycle (Ramondenc et al, 2019;Ballesteros et al, 2022). Additionally, due to its versatility and accessories, this system can be used for polyps, strobilae, eggs, planulae and grow-out ephyrae and metaephyrae tanks.…”