Bacteria associated with moon jellyfish during bloom and post-bloom periods in the Gulf of Trieste (northern Adriatic)

Abstract

Jellyfish are a prominent component of the plankton community. They frequently form conspicuous blooms which may interfere with different human enterprises. Among the aspects that remain understudied are jellyfish associations with microorganisms having potentially important implications for organic matter cycling. To the best of our knowledge, this study is the first to investigate the bacterial community associated with live moon jellyfish (Aurelia solida, Scyohozoa) in the Adriatic Sea. Using 16S rRNA clone libraries and culture-based methods, we have analyzed the bacterial community composition of different body parts: the exumbrella surface, oral arms, and gastric cavity, and investigated possible differences in medusa-associated bacterial community structure at the time of the jellyfish population peak, and during the senescent phase at the end of bloom. Microbiota associated with moon jellyfish was different from ambient seawater bacterial assemblage and varied between different body parts. Betaproteobacteria (Burkholderia, Cupriavidus and Achromobacter) dominated community in the gastral cavity of medusa, while Alphaproteobacteria (Phaeobacter, Ruegeria) and Gammaproteobacteria (Stenotrophomonas, Alteromonas, Pseudoalteromonas and Vibrio) prevailed on ‘outer’ body parts. Bacterial community structure changed during senescent phase, at the end of the jellyfish bloom, showing an increased abundance of Gammaproteobacteria, exclusively Vibrio. The results of cultured bacterial isolates showed the dominance of Gammaproeteobacteria, especially Vibrio and Pseudoalteromonas in all body parts. Our results suggest that jellyfish associated bacterial community might have an important role for the host, and that anthropogenic pollution in the Gulf of Trieste might affect their community structure.

The Microbial Community Associated with Rhizostoma pulmo: Ecological Significance and Potential Consequences for Marine Organisms and Human Health

“…While this study does not allow to understand the year-round microbiome composition, it gives a snapshot picture of two potentially opposite, temperature-dependent, jellyfish-associated microbial assemblages, so contributing to evaluate the role of jellyfish as "carrier" of microbial pathogens for humans or other marine organisms and/or as driver of the temporal microbial diversity. Changes of microbiome associated with different jellyfish species and geographical areas were previously investigated during episodic jellyfish blooms [22,23,38,39,68]. The present work aimed to ascertain whether a "core" of bacteria can be found to be associated with the "sea lung" or "barrel" jellyfish, R. pulmo, in both the warmest and coldest periods of the year.…”

“…In the present work, culturable methods, including the BIOLOG system, have been utilized to detect differences among microbiomes associated with different body compartments in the two sampling months (July 2016 vs February 2017). Although it is well known that the culture-based studies represent a limited compartment of total bacterial community [83][84][85], these techniques are also recognized as a crucial step for better integration of the physiological and ecological information [38,85,86]. The BIOLOG system has provided some pieces of information on the potential metabolic utilization of the 31 carbon sources by the microbial communities associated with the different examined compartments, showing that the umbrella microbiome utilized only few of the EcoPlate carbon sources in both the sampling months (July and February).…”

“…As reported by Tinta et al [35] early reports on microorganisms associated with jellyfish resulted as corollary observations, whereas primary targets of research were jellyfish [33,36,37]. Later studies, focusing on the relationships between microorganisms and their host organisms, addressed more specific issues on the composition and ecological role of jellyfish-associated microbial communities [35,38,39]. In the last decades, many studies revealed the role played by microorganisms in coral life histories, particularly the dynamic assemblage formed by the coral host, its endosymbiotic dinoflagellates, and a number of accompanying microorganisms, i.e., the coral holobiont [40][41][42].…”

“…So far, a limited number of studies explored different types of interactions between marine microbial communities and scyphozoan jellyfish, from host-microbiome interactions to quali-quantitative changes of microbial composition sampled across different life stages, medusa body parts, water samples, mostly on common semeostome jellyfish [22,23,35,38,[49][50][51][52][53][54][55]. To our knowledge, Mastigias papua, Cotylorhiza tuberculata, and Rhizostoma pulmo are the only rhizostome jellyfish species previously investigated with respect to their associated microbial community [39,50,51,55,56].…”

The effects of decomposing invasive jellyfish on biogeochemical fluxes and microbial dynamics in an ultra-oligotrophic sea

“…During the blooms, jellyfish propagate by assimilating organic compounds of their prey, thus acting as a nutrient sink of organic carbon (C), nitrogen (N), and phosphorus (P) (Lebrato and Jones, 2011; Lucas et al, 2011;Pitt et al, 2009). The death and sinking of jellyfish, followed by bacterial decomposition of their carcasses, lead to microbial community shifts (Kramar et al, 2019;Tinta et al, 2012;Titelman et al, 2006), resulting in oxygen depletion and acidification (Qu et al, 2015;Sweetman et al, 2016;West et al, 2008). On the seabed, jellyfish carcasses can be consumed by scavengers, thus acting as a rich carbon source that sustains benthic food webs (Hays et al, 2018;Sweetman et al, 2016Sweetman et al, , 2014.…”