Catostylus tagi (Class: Scyphozoa, Order: Discomedusae, Suborder: Rhizostomida, Family: Catostylidae) life cycle and first insight into its ecology

Abstract

Jellyfish proliferations, which are conspicuous and natural events, cause blooms that may lead to severe consequences for anthropogenic activities and ecosystem structure and functioning. Although research during the last decade has focused on factors influencing the different jellyfish life stages, few species currently have their full life cycle known. In this context, we describe for the first time the developmental stages in the life cycle of Catostylus tagi, from planula to young medusa, reared in the laboratory. The species displays the typical Rhizostomida metagenetic life cycle. Mature scyphistomae display 16 tentacles and a total body length of 1.5 ± 0.2 mm. Only podocyst production and strobilation were observed. Strobilation, occurring continuously under laboratory conditions, was mainly polydisc. The eight-rayed typical ephyrae, with a total body diameter of 2.4 ± 0.4 mm at detachment, showed development typical of the Rhizostomida. As a first step in studying this species’ ecology, we also present preliminary assessments of: (i) the influence of different temperature and salinity regimes on planulae survival, settlement and metamorphosis and (ii) the effect of temperature and diet on asexual reproduction. The results showed a high tolerance of planulae to a wide range of salinities (15‰ to 25‰), while polyp development was significantly faster at higher temperature (20–25 °C). Strobilation onset was 2–3 times faster at 20 °C (10.6 ± 5.4 to 15 ± 6.6 day at various tested diet) than at 15 °C (32.2 ± 3 day). Feeding was a key factor as unfed polyps never underwent strobilation during the trial. Finally, we present the spatial and seasonal distribution of C. tagi in the Tagus estuary (Portugal) in 2019, showing its occurrence throughout the year (except in April), with most observations recorded on the northern shoreline. As C. tagi shows the ability to form blooms and a wide tolerance for temperature and salinity (for planulae and medusae stage), it is essential to understand its life cycle.

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

“…with few released ephyrae that increased with time (Calder, 1982), as well as polyp size that agreed with that already reported for other species (Gueroun et al, 2021;Hernández-Tlapale, 2010) (Table 1).…”

“…The first planula larvae were observed 48 h after starting the experiment. The behavior observed in the scyphistoma stage agrees with that described for S. meleagris ; the strobilation process started with few released ephyrae that increased with time (Calder, 1982), as well as polyp size that agreed with that already reported for other species (Gueroun et al, 2021; Hernández‐Tlapale, 2010) (Table 1).…”

The unpredictability of scyphozoan jellyfish blooms

“…Scyphozoan planulae can settle on a variety of natural and artificial hard substrates, including shells, concrete, plastic, glass, wood, rope, seagrass, macroalgae, rocks, etc., with different efficiencies depending on the type and orientation of the substrate and the different scyphozoan species (Miyake et al, 2002;Malej et al, 2012;Marques et al, 2015;Franco, 2016;Gambill et al, 2018;van Walraven et al, 2020). There is an environmental control by factors such as temperature, salinity or light on the settlement and excystment of the planulae, providing an efficiency of the process, with the absence of competition for the substrate or predation, which decreases from a maximum of ~60% under the most suitable conditions to a minimum of 0% in a progression towards less suitable conditions (Prieto et al, 2010;Franco, 2016;Gambill et al, 2018;Feng et al, 2021;Gueroun et al, 2021;Holst et al, 2023). Even under the preferred environmental conditions and in the absence of competitors and predators, the settlement needs to occur within the first few days after planula release to prevent a significant decline in its effectiveness (Gambill et al, 2018).…”

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

“…Jellyfish are considered an important fishery commodity for the food industry (Omori and Nakano, 2001;Dong et al, 2009) and have a high value as raw material in a wide variety of biotechnological applications (Merquiol et al, 2019;D'Ambra and Merquiol, 2022). Although wild jellyfish are exploited as a marine resource for different proposals (Omori and Nakano, 2001;Dong et al, 2009;Elliott et al, 2017), they are considered unpredictable due to the seasonality and spatiotemporal variability of their life cycles (Purcell et al, 2013;Gueroun et al, 2021;Marambio et al, 2021). From this point of view, biomass production through aquaculture activity can offer a permanent stock to supplement the fished biomass, as well as, to assures individuals not contaminated with unknown pollutants and safeguards traceability; a plus when aiming to target premium sectors associated with pharmaceutical, cosmeceutical and biomedical industries.…”

“…To raise jellyfish successfully, knowledge on the biology of target species is required including their feeding and reproductive behavior (Fu et al, 2014;Lilley et al, 2014b;Gueroun et al, 2021;Camacho-Pacheco et al, 2022). The majority of the scyphozoan species (Cnidaria: Scyphozoa) have a well-known metagenetic life cycle.…”