Is jellyfish mucus spreading pathogenic disease?

The warmer waters during summer allow jellyfish populations to bloom, and with them may come a greater risk of disease. Through a combination of culture-based and molecular techniques Basso, et al. (2019) investigated the microbiome within various regions; mucus secretion, umbrella and arms, of the jellyfish species, Rhizostoma pulmo. This paper highlighted that each region has its own bacterial community. Notably, the mucus provides a substrate for a particularly diverse and rich array of bacteria. However, within these communities several pathogenic genera of bacteria were found, including Vibrio, Coxiella and Tenacibaculum.

As a planktonic species, R. pulmo secrete mucus whilst they passively drift through their surroundings. This means they can potentially inoculate large areas of water, acting as mobile vectors for bacterial pathogens. With climate change leading to rising water temperatures, could a resulting increase in jellyfish populations lead to greater outbreaks of disease?

Furthermore, whilst the study focuses on the potential hazard this poses, I feel it also calls into question whether other cnidarian species, with different mucus compositions, harbour their own unique microbiomes. If this is the case, then outbreaks of certain species could potentially act as indicators for the increased presence of certain pathogens within the environment.

Basso, L., Rizzo, L. , Marzano, M., Intranuovo, M., Fosso, B., Pesole, G., Piraino, S.,  Stabili, L. (2019). Jellyfish summer outbreaks as bacterial vectors and potential hazards for marine animals and humans health? The case of Rhizostoma pulmo (Scyphozoa, Cnidaria). Science of the Total Environment, 692, 305–318.