Dynamic Model for Life History of Scyphozoa

Abstract

A two-state life history model governed by ODEs is formulated to elucidate the population dynamics of jellyfish and to illuminate the triggering mechanism of its blooms. The polyp-medusa model admits trichotomous global dynamic scenarios: extinction, polyps survival only, and both survival. The population dynamics sensitively depend on several biotic and abiotic limiting factors such as substrate, temperature, and predation. The combination of temperature increase, substrate expansion, and predator diminishment acts synergistically to create a habitat that is more favorable for jellyfishes. Reducing artificial marine constructions, aiding predator populations, and directly controlling the jellyfish population would help to manage the jellyfish blooms. The theoretical analyses and numerical experiments yield several insights into the nature underlying the model and shed some new light on the general control strategy for jellyfish.

Ecological drivers of jellyfish blooms – The complex life history of a ‘well‐known’ medusa (Aurelia aurita)

“…Our findings emphasize the crucial role of predation by benthic fauna, spatial competition and availability of settlement substrate for transition from the planktonic planula to the benthic polyp stage under natural conditions (Lucas, ; Lucas et al, ). We estimated a transition probability of 0.001 month −1 from larva to polyp, which agrees with previous estimates for A. aurita (Xie et al, ), when scaling to a stable A. aurita population under low food levels ( λ = 1 month −1 ). The local A. aurita jellyfish population in the semi‐enclosed fjord system Kerteminde Fjord/Kertinge Nor, where zooplankton biomasses are comparable to our low food conditions, has remained unchanged over the last 25 years (Goldstein & Riisgård, ; Olesen et al, ; Riisgård et al, ) and may, similar to our projected A. aurita population, mainly depend on environmental parameters that determine larval transition to the benthic polyp stage.…”

“…As reflected by doubled yearly population growth rates under high food conditions in response to the simulated increase in winter temperatures, our findings support that increased water temperature can boost the future booms and busts of jellyfish blooms (cf. Richardson et al, ; Xie et al, ). According to our population matrix model, underlying seasonal changes in population composition and structure in response to winter warming include a general trend towards more medusae and fewer polyps under increased food conditions.…”

“…Gröndahl, 1989;Hamner & Jenssen, 1974;Liu, Lo, Purcell, & Chang, 2009). Although the development of medusa populations is directly linked to survival rates of several precedent life stages, that is, planula larvae, polyps and ephyrae (Lucas, 2001), information on the demographic rates of bloom-forming jellyfish has remained scarce (Xie, Fan, Wang, & Chen, 2015). Quantifying demographic rates of all stages in the life cycle of species showing mass occurrence is thus fundamental to identifying the environmental variables causing changes in population dynamics and structure.…”

Modeling population dynamics of scyphozoan jellyfish (Aurelia spp.) in the Gulf of Mexico

“…Existing jellyfish models, whether they are bioenergetics-based (Haraldsson et al 2012), logistical (Melica et al 2014) or statistical (Decker et al 2007), only considered 1 life history stage. The first dynamic scyphozoan model that included both polyp and medusa life history stages incorporated temperature-dependent relationships, but ignored feeding and somatic growth (Xie et al 2015). By incorporating feeding and somatic growth in our model, this model builds on previous jellyfish model frameworks such as that of Xie et al (2015) by incorporating additional consumption-dependent terms such as starvation mortality and shrinkage, as well as including consumption requirements for the rate of ephyrae production.…”

“…The first dynamic scyphozoan model that included both polyp and medusa life history stages incorporated temperature-dependent relationships, but ignored feeding and somatic growth (Xie et al 2015). By incorporating feeding and somatic growth in our model, this model builds on previous jellyfish model frameworks such as that of Xie et al (2015) by incorporating additional consumption-dependent terms such as starvation mortality and shrinkage, as well as including consumption requirements for the rate of ephyrae production. In this model, zooplankton biomass and temperature were sufficient drivers to create realistic seasonal and inter-annual population dynamics of Aurelia spp.…”