Climate change is linked to changes in the distribution and phenology of plankton through several trophic levels, with potential impacts on pelagic food webs. Global warming and other anthropogenic ...stresses have also been implicated in proposed large-scale increases in jellyfish numbers. We have analyzed a 1992 to 2011 time series on occurrence of common scyphozoan jellyfish at a Skagerrak location for changes in their abundance and phenology, and attempted to relate these observations to environmental and climatic variables including temperature, salinity, chl a concentration, zooplankton prey biomass and the North Atlantic Oscillation index using generalized linear models (GLMs). Cyanea spp. abundances showed no significant trend during the study period. Their fluctuations were positively related to temperature and prey availability, with possible impacts on the polyp generation. The central tendency of annual Cyanea spp. abundance showed a borderline significant shift towards a later date, while zooplankton biomass showed the opposite trend, suggesting potential change in trophic match. Aurelia aurita abundance exhibited a considerable decline and 5-yr cyclicity, but neither pattern was explained by any of the investigated explanatory variables. Unidentified factors causing cyclicity may include predatory interactions or density-dependent processes, possibly involving the benthic stages. Observed changes in abundance may also be related to a possible regime shift in the Norwegian Skagerrak area around the turn of the millennia. Our results highlight the importance of considering changes in jellyfish abundances with regard to locality and species. Improved understanding of polyp ecology seems necessary for understanding fluctuations in jellyfish numbers.
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BFBNIB, NUK, PNG, UL, UM, UPUK
The present work was carried out to identify the anti-oxidant and anti-diabetic activities of Aurelia aurita. The chemical profiling analysis showed that it possess different biologically active ...secondary metabolites like phenols, alakoids, steroids etc. The methanolic extract showed different free radical scavenging activity as ascorbic acid with IC50 values 202, 205, 153 µg on DPPH, hydroxyl and superoxide free radicals. The extract significantly reduced the hyperglycemic conditions with percentage of reduction 18.7 ± 1.3 to 53.5 ±1.5 of streptozotocin-induced animals and the positive result of in-vitro aldose reductase enzyme inhibition with IC50 value 163 µg suggests that A. aurita have potential to cure the diabetic complications.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
All multicellular organisms are associated with microbial communities, ultimately forming a metaorganism. Several studies conducted on well-established model organisms point to immunological, ...metabolic, and behavioral benefits of the associated microbiota for the host. Consequently, a microbiome can influence the physiology of a host; moreover, microbial community shifts can affect host health and fitness. The present study aimed to evaluate the significance and functional role of the native microbiota for life cycle transitions and fitness of the cnidarian moon jellyfish
A comprehensive host fitness experiment was conducted studying the polyp life stage and integrating 12 combinations of treatments with microbiota modification (sterile conditions, foreign food bacteria, and potential pathogens). Asexual reproduction, e.g., generation of daughter polyps, and the formation and release of ephyrae were highly affected in the absence of the native microbiota, ultimately resulting in a halt of strobilation and ephyra release. Assessment of further fitness traits showed that health, growth, and feeding rate were decreased in the absence and upon community changes of the native microbiota, e.g., when challenged with selected bacteria. Moreover, changes in microbial community patterns were detected by 16S rRNA amplicon sequencing during the course of the experiment. This demonstrated that six operational taxonomic units (OTUs) significantly correlated and explained up to 97% of fitness data variability, strongly supporting the association of impaired fitness with the absence/presence of specific bacteria. Conclusively, our study provides new insights into the importance and function of the microbiome for asexual reproduction, health, and fitness of the basal metazoan
All multicellular organisms are associated with a diverse and specific community of microorganisms; consequently, the microbiome is of fundamental importance for health and fitness of the multicellular host. However, studies on microbiome contribution to host fitness are in their infancy, in particular, for less well-established hosts such as the moon jellyfish
Here, we studied the impact of the native microbiome on the asexual reproduction and on further fitness traits (health, growth, and feeding) of the basal metazoan due to induced changes in its microbiome. We observed significant impact on all fitness traits analyzed, in particular, in the absence of the protective microbial shield and when challenged with marine potentially pathogenic bacterial isolates. Notable is the identified crucial importance of the native microbiome for the generation of offspring, consequently affecting life cycle decisions. Thus, we conclude that the microbiome is essential for the maintenance of a healthy metaorganism.
A three-stage (Medusa-Polyp-Ephyra) life history model of Aurelia aurita is formulated to investigate the role of ephyra and explore the ecological effects of sea surface temperature and seawater ...salinity on blooms. Both theoretical analyses and numerical simulations explain the mechanisms of A. aurita blooms in specific seasons. Sensitivity analyses (SAs) characterize the key factors that affect population sizes and provide a basis for feasible and effective control recommendations. In agreement with observational data, we then summarize the interannual variation patterns in the A. aurita population in Jiaozhou Bay and generalize its distribution in the Yellow Sea. This study shows that the occurrence of strobilation, ephyra development, and degree of asexual reproduction can significantly influence the steady states of A. aurita. Moreover, the population size of medusae is sensitive to medusa mortality and strobilation. The findings provide some valuable insights into revealing the mechanisms of A. aurita blooms and explain the connection between its population dynamics and environmental factors.
•MPE model characterizes the effects of temperature and salinity on Aurelia aurita.•Medusae are mainly dependent on the bottom-up supplement of strobilation.•Substrate constraint is more feasible and flexible to control Aurelia aurita bloom.•Seasonal variation mainly affects Aurelia aurita by regulating strobilation.•Quantity variance in the Yellow Sea is affected by latitude distributions.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
The concept of the metaorganism describes a multicellular host and its diverse microbial community, which form one biological unit with a combined genetic repertoire that significantly influences ...health and survival of the host. The present study delved into the emerging field of bacteriophage research within metaorganisms, focusing on the moon jellyfish
as a model organism. The previously isolated
phage BSwM KMM1 and
phages BSwM KMM2 - KMM4 demonstrated potent infectivity on bacteria present in the
-associated microbiota. In a host-fitness experiment, Baltic Sea subpopulation polyps were exposed to individual phages and a phage cocktail, monitoring polyp survival and morphology, as well as microbiome changes. The following effects were obtained. First, phage exposure in general led to recoverable malformations in polyps without affecting their survival. Second, analyses of the community structure, using 16S rRNA amplicon sequencing, revealed alterations in the associated microbial community in response to phage exposure. Third, the native microbiota is dominated by an uncultured likely novel
species, potentially specific to
. Notably, this main colonizer showed resilience through the recovery after initial declines, which aligned with abundance changes in Bacteroidota and Proteobacteria, suggesting a dynamic and adaptable microbial community. Overall, this study demonstrates the resilience of the
metaorganism facing phage-induced perturbations, emphasizing the importance of understanding host-phage interactions in metaorganism biology. These findings have implications for ecological adaptation and conservation in the rapidly changing marine environment, particularly regarding the regulation of blooming species and the health of marine ecosystems during ongoing environmental changes.
The population density and individual size of the common jellyfish Aurelia aurita were studied during 2014 and 2015 in two Danish fjord systems, Kertinge Nor and Mariager Fjord in order to obtain a ...better understanding of the driving forces for somatic degrowth (shrinkage) of medusa during late summer and autumn. In both fjord systems the numerous medusae were characterized by their small body size and by a distinct phase of degrowth. The population predation impact of A. aurita, with estimated zooplankton half-lives of only about 1 to 3 d, indicated that shortage of prey controls the maximum umbrella size of only 60 (Kertinge Nor) to 100 mm (Mariager Fjord) and the subsequent degrowth. When jellyfish were brought into the laboratory in early spring and the late degrowth period and continuously fed with zooplankton (Artemia salina), equivalent to 5.8 mu g C l-1, this resulted in initial growth rates of 11.3 and 24.4 % d-1 in two series of experiments with 56.9 and 5.5 mm umbrella diameter, respectively, and considerably longer survival than of jellyfish in their natural environment. The degrowth rates in Kertinge Nor (-1.2 % d-1) and Mariager Fjord (-1.5 and -0.7 % d-1 in 2014 and 2015, respectively) were slightly lower than observed in laboratory starvation experiments (-3.2 and -4.2 % d-1), indicating that the starvation of jellyfish in nature was less pronounced, i.e. some prey organisms may have been available although the short estimated half-lives of zooplankton suggested a pronounced predation impact exerted by the jellyfish.
Introduction The associated diverse microbiome contributes to the overall fitness of Aurelia aurita, particularly to asexual reproduction. However, how A. aurita maintains this specific microbiome or ...reacts to manipulations is unknown. Methods In this report, the response of A. aurita to manipulations of its native microbiome was studied by a transcriptomics approach. Microbiome-manipulated polyps were generated by antibiotic treatment and challenging polyps with a non-native, native, and potentially pathogenic bacterium. Total RNA extraction followed by RNAseq resulted in over 155 million reads used for a de novo assembly. Results The transcriptome analysis showed that the antibiotic-induced change and resulting reduction of the microbiome significantly affected the host transcriptome, e.g., genes involved in processes related to immune response and defense mechanisms were highly upregulated. Similarly, manipulating the microbiome by challenging the polyp with a high load of bacteria (2 × 10 7 cells/polyp) resulted in induced transcription of apoptosis-, defense-, and immune response genes. A second focus was on host-derived quorum sensing interference as a potential defense strategy. Quorum Quenching (QQ) activities and the respective encoding QQ-ORFs of A. aurita were identified by functional screening a cDNA-based expression library generated in Escherichia coli. Corresponding sequences were identified in the transcriptome assembly. Moreover, gene expression analysis revealed differential expression of QQ genes depending on the treatment, strongly suggesting QQ as an additional defense strategy. Discussion Overall, this study allows first insights into A. aurita’s response to manipulating its microbiome, thus paving the way for an in-depth analysis of the basal immune system and additional fundamental defense strategies.
Jellyfish blooms are conspicuous demographic events with significant ecological and socio‐economic impact. Despite worldwide concern about an increased frequency and intensity of such mass ...occurrences, predicting their booms and busts remains challenging.
Forecasting how jellyfish populations may respond to environmental change requires considering their complex life histories. Metagenic life cycles, which include a benthic polyp stage, can boost jellyfish mass occurrences via asexual recruitment of pelagic medusae.
Here we present stage‐structured matrix population models with monthly, individual‐based demographic rates of all life stages of the moon jellyfish Aurelia aurita L. (sensu stricto). We investigate the life‐stage dynamics of these complex populations under low and high food conditions to illustrate how changes in medusa density depend on non‐medusa stage dynamics.
We show that increased food availability can be an important ecological driver of jellyfish mass occurrences, as it can temporarily shift the population structure from polyp‐ to medusa‐dominated. Projecting populations for a winter warming scenario additionally enhanced the booms and busts of jellyfish blooms.
We identify demographic key variables that control the intensity and frequency of jellyfish blooms in response to environmental drivers such as habitat eutrophication and climate change. By contributing to an improved understanding of mass occurrence phenomena, our findings provide perspective for future management of ecosystem health.
Despite worldwide concern about an increased frequency and intensity of jellyfish mass occurrences, predictions remain challenging due to complex life histories. In this study, the authors present stage‐structured matrix population models with monthly, individual‐based demographic rates of all life stages of the moon jellyfish Aurelia aurita and unravel key mechanisms that can promote jellyfish blooms in response to environmental change.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
Jellyfish are voracious planktonic predators that may be susceptible to ingesting microplastics. We measured rates of ingestion and egestion of microbeads by Aurelia aurita (Scyphozoa) and evaluated ...whether ingesting microbeads affected metabolism or gut epithelia. Ingestion rates were measured by exposing medusae to microbeads and randomly sampling them 6 times over a 32 h period to determine the number of microbeads in their tissues. Egestion rates were measured by exposing medusae to microbeads for 1 h before transferring them to kreisels without microbeads and sampling them 6 times over 8 h. Respiration rates of medusae were determined using incubations and potential damage to gut epithelia was evaluated using histopathology. Medusae ingested few microbeads and egested them within 8 h. Microbeads had no effect on respiration and the histology. We concluded that the medusae may recognise microbeads as non-food particles and that their ingestion caused undetectable physiological and histological harm.
•Medusae of the moon jellyfish, Aurelia aurita, inefficiently ingested microbeads.•Medusae egested the microbeads within 8 h.•Microbeads caused no detectable physiological and histological harm.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
•We reviewed environmental and ecosystem changes in two LTER sites in the N hemisphere.•We examined the effects of anthropogenic pressures on moon jellyfish populations.•A synchronous shift in ...climate was detected in the 1980s in both systems.•Providing additional space for polyps, marine urbanisation-enhanced jellyfish population.•Fish-dominated ecosystem switched to “jellyfish-permeated” environment.
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A prominent increase in the moon jellyfish (genus Aurelia) populations has been observed since 1980 in two semi-enclosed temperate seas: the northern Adriatic Sea and the Inland Sea of Japan. Therefore, we reviewed long-term environmental and biotic data from the two Long-Term Ecological Research (LTER) sites, along with the increase in the moon jellyfish occurrence to elucidate how these coastal seas shifted to the jellyfish-dominated ecosystems. The principal component analysis of atmospheric data revealed a simultaneous occurrence of similar climatic changes in the early 1980s; thereafter, air temperature increased steadily and precipitation decreased but became more extreme. Accordingly, the average seawater temperature from March to October, a period of polyps' asexual reproduction i.e. budding, increased, potentially leading to an increase in the reproductive rates of local polyp populations. Conspicuous eutrophication occurred due to the rise of anthropogenic activities in both areas from the 1960s onwards. This coincided with an increase of the stock size of forage fishes, such as anchovy and sardine, but not the population size of the jellyfish. However, by the end of the 1980s, when the eutrophication lessened due to the regulations of nutrients loads from the land, the productive fishing grounds of both systems turned into a state that may be described as ‘jellyfish-permeated,’ as manifested by a drastic decrease in fish landings and a prominent increase in the intensity and frequency of medusa blooms. A steady increase in artificial marine structures that provide substrate for newly settled polyps might further contribute to the enhancement of jellyfish population size. Elevated fishing pressure and/or predation by jellyfish on ichthyoplankton and zooplankton might jeopardize the recruitment of anchovy, so that the anchovy catch has never recovered fully. These semi-enclosed seas may represent many temperate coastal waters with increased anthropogenic stressors, which have degraded the ecosystem from fish-dominated to jellyfish-dominated.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
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