The increase of nuisance blooms of specific organisms in the world’s oceans has been linked to anthropogenic impacts, climate change and the associated deterioration of ecosystems. These blooms often abruptly collapse, inducing major perturbations to the ecosystem and its services. The factors and mechanisms behind this type of dynamics remain enigmatic. Knowledge of these factor and mechanisms is needed to predict the blooms of invasive and native species and mitigate deleterious effects on ecosystems.

While the importance of the microbiome for its host’s traits is increasingly recognized, its role in the boom-and-bust population dynamics of its host is still unknown. Massive jellyfish blooms often occur seasonally, are short-lived and often collapse abruptly. The role of the microbiome in the life and death of jellyfish remains largely unknown. However, we hypothesize that the microbiota plays an important role in the host’s defense mechanisms and contributes to the survival of the planktonic stage of jellyfish and their adaptability to new environmental conditions. We also hypothesize that the defense performance of the jellyfish microbiome is variable and structured by the host environment and age- or stress-related changes of the host physiology.

The overarching ambition of the JELLY-BIOME project is to investigate the composition and functional traits of the jellyfish microbiome at the transition from a healthy to senescent stage of the host’s bloom and to explore the role of the microbiome in the bust and collapse of jellyfish blooms.

Our study will elucidate the microbiome-jellyfish interactions at the molecular level in unprecedented detail by merging meta-genomics, -transcriptomics and -proteomics with microscopy-based techniques beyond the state-of-the-art. We will exploit the power of machine learning to infer patterns and mechanisms underlying jellyfish-microbiome interactions. We will apply latest molecular biology and biochemistry approaches to study in-detail key proteases of the host and the microbiome involved in the host decay and death.

The results of JELLY-BIOME will provide insights into the interplay between jellyfish and their microbiota, and will resolve the reasons behind the massive decay of gelatinous zooplankton particularly in coastal regions.