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

DARNAUDE, D.; MOLINERO, J. C.; MARQUES, R.; TREMBLAY, J.; BONNET, D.; SCHIARITI, A.; SOLEM, S.

MARINE BIOLOGY

SPRINGER

Lugar: Berlin; Año: 2019 vol. 166

0025-3162

Themagnitude and timing of most jellyfish blooms are directly linked totheir benthicpopulation dynamics. Despite the recognized importance of polyps, this stage oftheir life cycle is still poorly understood and field studies are still scarce.The semi enclosed Thau lagoonharbors a resident population of Aurelia coeruleawith polyps beingbroadly distributed over the entire lagoon, offering the ideal framework toinvestigate them. Here, two complementary approaches (photoquadrats and sampleanalysis) were carried out every two weeks for one year to surveythe temporalvariability of polyps population dynamics and asexual reproduction strategies.We show that polyps follow a different seasonality from what was previouslyreported. Polyps colonies grow until its maximum in April, decreasing to nearlyabsence at the end of the summer (September to November). Such dynamics appearto be mostly driven by temperature, mesozooplankton abundance, and salinity,with high summer values potentially inducing physiological stress. Interspecificrelationships might also play an important role in the control of the polypspopulation.The loss of coverage of some benthic organisms (e.g. red algae)might reduce the density of polyps by decreasing the suitable settlingsubstrates.The production of buds occurred during all year round, with maximumvalues in spring and minimum values in November, when polyps relocate theirenergy to the strobilation process. Bearing in mind that, in November, thedensity of polyps is at its minimum, our results warn on the potential reductionof A. coerulea blooms in Thau lagoon inyears of warm and dry summers. Here we provide evidences that not all speciesof the Aurelia genus will respondepositively to the predicted global warming scenario.