Mechanisms behind the metabolic flexibility of an invasive comb jelly

Mnemiopsis leidyiis an invasive comb jelly which has successfully establisheditself in European seas. The speciesis known to produce spectacular blooms yet it is holoplanktonic and not much is known about its populationdynamics in between. One way to gain insight on howM. leidyimight survive between blooms and how it canbloom so fast is to study how the metabolism of this species actually responds to environmental changes infood and temperature over its different life-stages. To this end we combined modelling and data analysis tostudy the energy budget ofM. leidyiover its full life-cycle using Dynamic Energy Budget (DEB) theory andliterature data.An analysis of data obtained at temperatures ranging from 8 to 30 °C suggests that the optimum thermaltolerance range ofM. leidyiis higher than 12 °C. FurthermoreM. leidyiseems to undergo a so-called metabolicacceleration after hatching. Intriguingly, the onset of the acceleration appears to be delayed and the data donot yet exist which allows determining what actually triggers it. It is hypothesised that this delay confers a lotof metabolicflexibility by controlling generation time.We compared the DEB model parameters for this species with those of another holoplanktonic gelatinouszooplankton species (Pelagia noctiluca). After accounting for differences in water content, the comparisonshows just how fundamentally different the two energy allocation strategies are.P. noctilucahas an extremelyhighreservecapacity,lowturnovertimesofreservecompoundsandhighresistancetoshrinking.M.leidyiadoptsthe opposite strategy:ithas a low reserve capacity, highturnover ratesofreserve compounds and fastshrinkin