Natural predators of polyps of Aurelia aurita s.l. (Cnidaria: Scyphozoa: Semaeostomeae) and their predation rates

Abstract

Abstract:The size of medusa populations in most scyphozoan species can be affected by the size of their benthic polyp populations, which reproduce asexually to give birth to planktonic ephyrae, but also are subject to predation by natural enemies. In this study, five gastropod species (Calliostoma unicum, Pleurobranchaea japonica, Hermissenda crassicornis, Sakuraeolis enosimensis and S. sakuracea) and three crustacean species (Rhynchocinetes uritai, Latreutes anoplonyx and Hyastenus diacanthus) were found to prey on polyps of the moon jellyfish, Aurelia aurita s.l., in Japanese coastal waters. In particular, C. unicum, P. japonica, H. crassicornis, R. uritai and H. diacanthus consumed more than 300 polyps per predator per day in the laboratory. These predators are common on natural rocky or pebbled seabeds, but are very scarce on various substrates in concrete-walled fishing ports, particularly on the undersurfaces of floating piers, where A. aurita polyps are attached in abundance. Transplanting natural predators to substrates with dense polyp colonies, just prior to their seasonal strobilation, is a possible countermeasure to prevent recurrent medusa blooms.

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

“…However, the impacts of biotic and abiotic factors on the wild benthic population dynamics of these jellyfish are complex and still poorly known (Willcox et al 2008;Malej et al 2012;Hocevar et al 2018). Density dependent factors, predation and interspecific space competition were also stressed as important potential drivers of scyphistoma densities, both from in situ (Miyake et al 2002;Willcox et al 2008;Feng et al 2017;Dong et al 2018) and laboratory studies (Hoover et al 2012;Takao et al 2014).…”

Mapping distribution and habitats of Aurelia sp. polyps in Thau lagoon, north-western Mediterranean Sea (France)

“…Despite the importance of the benthic population for bloom dynamics, in situ investigations were only recently performed (e.g. Hoover and Purcell 2009;Purcell et al 2009;Takao et al 2014;Qiu 2014;Makabe et al 2014). To our knowledge, direct investigations of benthic population distribution over large spatial scales were only performed in Mikawa Bay, Japan (Toyokawa et al 2011).…”

Evolution of Complex Asexual Reproductive Strategies in Jellyfish

“…High local extinction risk is common among polyp populations, as they typically occupy habitats characterized by frequent disturbances and intense competition for space (Clark 1975). Moreover, common predators of jellyfish polyps, like nudibranch mollusks, have high efficiency but low mobility, such that they are patchily distributed and tend to completely clear an area of polyps (Hoover et al 2012;Takao et al 2014). For example, the genus Aurelia, arguably the most successful jellyfish in the world, often inhabits variable and changeable estuarine and shallow environments (Lucas and Williams 1994;Lucas 2001;Møller and Riisgård 2007) and commonly employs all three reproductive modes.…”