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Pelagic cnidarians have been observed stranding annually in the Tetouanise Sea, a site of intense human recreation in northwest Morocco. The abundance and size of jellyfish stranded, between January 2018 and December 2020, on the beaches of the Moroccan Mediterranean were investigated. We present data on the temporal and spatial distribution of the species in relation to environmental variables (e.g., sea surface temperature, salinity, chlorophyll and wind direction). We also examined the negative impacts of jellyfish on human activities in the Moroccan Mediterranean. Five species that represented three scyphozoans and two hydrozoans were frequently observed: Pelagia noctiluca, Velella velella, Physalia physalis, Rhizostoma pulmo and Chrysaora hysoscella. Three different models of seasonal occurrence of jellyfish were identified in this study: (1) P. noctiluca appears throughout the year but with a higher frequency during the summer, (2) P. physalis and V. velella appear in March–May and (3) the late appearing R. pulmo and C. hysoscella from July to August. The abundance of jellyfish varied from season to season, but did not differ between sampling sites. Interannual variations in the abundance of jellyfish were not significantly correlated with the environmental factors examined. However, the east wind played an important role in the stranding and formation of hotspots for jellyfish in the Moroccan coast. Continuous monitoring is needed for a more profound knowledge on the jellyfish bloom dynamics and their potential impacts on ecosystem functioning and socioeconomic activities in the Moroccan Mediterranean.

Jellyfish are useful genetic indicators for aquatic ecosystems as they have limited mobility and are highly exposed to the water column. By using comparative genomics and the molecular clock (timetree) of Rhizostoma pulmo, we revealed a divergence point between the East and West Mediterranean Sea (MS) populations that occurred 4.59 million years ago (mya). It is suggested that the two distinct ecological environments we know today were formed at this time. We propose that before this divergence, the highly mixed Atlantic and Mediterranean waters led to the wide dispersal of different species including R. pulmo. At 4.59 mya, the Western and Eastern MS were formed, indicating the possibility of a dramatic environmental event. For the first time, we find that for the jellyfish we examined, the division of the MS in east and west is not at the Straits of Sicily as generally thought, but significantly to the east. Using genomics of the Aurelia species, we examined contemporary anthropogenic impacts with a focus on migration of scyphozoa across the Suez Canal (Lessepsian migration). Aurelia sp. is among the few scyphozoa we find in both the MS and the Red Sea, but our DNA analysis revealed that the Red Sea Aurelia sp. did not migrate or mix with MS species. Phyllorhiza punctata results showed that this species was only recently introduced to the MS as a result of anthropogenic transportation activity, such as ballast water discharge, and revealed a migration vector from Australia to the MS. Our findings demonstrate that jellyfish genomes can be used as a phylogeographic molecular tool to trace past events across large temporal scales and reveal invasive species introduction due to human activity., With the use of genetic tools, we revealed a divergence point between the East and West Mediterranean Sea populations that occurred 4.59 million years ago, and we propose that the western and eastern Mediterranean Sea were formed at that time. For the first time, we find that the division of the Mediterranean Sea in east and west is not at the Strait of Sicily, but significantly to the east. Aurelia sp. DNA analysis revealed that the Red Sea Aurelia sp. did not migrate or mix with Mediterranean Sea species. Phyllorhiza punctata results showed that this species was only recently introduced to the Mediterranean Sea from Australia due to human activity.

The antioxidant activity (AOA) of the dry residue of jellyfish Rhizostoma pulmo was investigated using in vitro method with DPPH reagent, in different concentrations and solvents. The obtained results showed the presence of dose-dependent antiradical activity of the extract from the dry residue of jellyfish. Исследована антиоксидантная активность (АОА) сухого остатка медузы Rhizostoma pulmo с помощью in vitro метода с DPPH реактивом, в различных концентрациях и растворителях. Полученные результаты показали наличие дозозависимой противорадикальной активности экстракта сухого остатка медуз. Дослiджено антиоксидантну активнiсть (АОА) сухого залишку медузи Rhizostoma pulmo за допомогою in vitro методу з DPPH реактивом, у рiзних концентрацiях та розчинниках. Отриманi результати показали наявнiсть дозозалежної протирадикальної активностi екстракту з сухого залишку медуз.

Funding: The publication of this manuscript was kindly funded by the state of Bremen. JL acknowledges financial support through Postgraduate Research Scholarships awarded by Griffith University. Many pigments, such as melanins, are widely distributed throughout the animal kingdom. Others have arisen as novelties in particular lineages, for example, the Green Fluorescent Protein (GFP) found in cnidarians. While GFPs, widely used as fluorescent tags in biomedical research, are the most famous cnidarian example, other novel proteins have also been identified within this phylum. A blue protein that contains a Kringle (KR) domain inserted within a Frizzled cysteine-rich domain (Fz-CRD) was previously described from the jellyfish Rhizostoma pulmo (named rpulFKz1), however little is known about this pigment’s evolution or distribution among cnidarians. We performed a systematic search for homologs of this protein in published genomes and transcriptomes of 93 cnidarians. Phylogenetic analyses revealed eight predicted proteins that possess both domains in the same arrangement and that fall within the same clade as rpulFKz1. The sequence of one of these proteins contains motifs that match sequenced peptides of Cassio Blue, the blue pigment from Cassiopea xamachana. Another one of these proteins belongs to Stomolophus meleagris, and chemical studies on blue pigments that may occur in this genus have shown similarities to rpulFKz1 and Cassio Blue. Therefore, we hypothesize that the eight rpulFKz1 homologs identified are also pigment precursors. All precursors identified were exclusive to jellyfish in the order Rhizostomeae, so we herein name this new pigment family “rhizostomins.” Not all rhizostomes analyzed are blue, however, so these rhizostomin proteins may also be responsible for other colors, or perform other biochemical and biophysical roles. Previous studies have hypothesized that cnidarian pigments are photoprotective, and this study serves as basis for future investigations not only on the function of rhizostomins, but also on potential biotechnological applications for these proteins. Publisher PDF

Jellyfish locomotion and orientation have been studied in the past both in the laboratory, testing mostly small jellyfish, and in the field, where it was impossible to control the seawater currents. Utilizing an outdoor water flume, we tested the locomotion of jellyfish when swimming against and with currents of up to 4.5 cm s−1. We used adult jellyfish from two of the most abundant species in the eastern Mediterranean, Rhopilema nomadica and Rhizostoma pulmo, and measured their pulsation frequency and swimming speed relative to the water. While pulsation frequency was not affected by the water velocity, jellyfish swam faster against the current than with it. This finding suggests that jellyfish possess a sensory ability, whose mechanism is currently unknown, enabling them to gauge the flow and react to it, possibly in order to reduce the risk of stranding.

WOS: 000496712300005 In this study, gastric contents of the medusa Rhizostoma pulmo distributed along the Samsun coast of the Black Sea were investigated between August 2008 and January 2010. Moreover, the relationship between the umbrella diameter and prey selectivity was determined. Captured R. pulmo individuals during the sampling period varied from 14.5 to 42.5 cm in umbrella diameter. The largest umbrella diameter was observed in October in both periods of the present study. Gastric contents of total 231 R. pulmo individuals have been gathered during the sampling period from all stations. 31 taxa, 10 larvae, 2 nauplii and fish and Copepod eggs from 11 phyla have been identified in the gastric contents of R. pulmo individuals. It has been detected that, feeding choices of R. pulmo individuals have differentiated and their food count has increased due to increasing umbrella diameter (according to Spearman rank correlation, r=0.70; p

9 pages, 6 figures, 2 tables, This study analyses the trophic ecology of the horse mackerel (Trachurus mediterraneus) juveniles associated with two jellyfish species, Rhizostoma pulmo and Cotylorhiza tuberculata, in the NW Mediterranean. The aim was to know whether the natural diet composition of the hosted fish could be influenced by the jellyfish species and to explore if the fish could feed on the host jellyfish. Samplings were carried out off the coast of Barcelona in summer 2011 at depths of up to 10 m. Juveniles associated with C. tuberculata showed a higher feeding incidence and number of ingested prey than those associated with R. pulmo. The relative importance of the different prey varied depending on the jellyfish species with which fish were associated. In juveniles associated with C. tuberculata, the diet was similar to the composition of the ambient zooplankton, with the cladocera Evadne spp. and Calanoida copepods as the most important prey. However, juveniles associated with R. pulmo fed mainly on Calanoida and Harpacticoida copepods. These differences could be related to the depth-associated behaviour of each jellyfish species, with R. pulmo particularly making deeper living plankton accessible to the horse mackerel juveniles. The presence of nematocyst cells in the juvenile gut contents suggests that they fed on the host jellyfish, either directly on the jellyfish tissue or accidentally when they remove the prey captured by the jellyfish oral arms. Our results provide a better understanding of the associations between jellyfish and juvenile fish which can have important effects on fish population dynamics, This work was supported by the Spanish Ministry of Economy and Competitiveness (CTM2010-18874 and CTM2015-68543-R). JM was supported by a predoctoral FI-AGAUR fellowship of the University and Research Grants Management Agency (AGAUR) of the Government of Catalonia (Generalitat de Catalunya) (FI_B_00412)

Monitoring the spreading of marine invasive species represents one of the most relevant challenges for marine scientists in order to understand their impact on the environment. In recent years, citizen science is becoming more and more involved in research programs, especially taking advantage of new digital technologies. Here, we present the results obtained in the first 20 months (from 12 July 2019 to 8 March 2021) since launching avvistAPP. This new app was conceived to track the spreading of the invasive ctenophore Mnemiopsis leidyi in the Adriatic Sea, it was also designed to collect sightings of 18 additional marine taxa (ctenophores, jellyfish, sea turtles, dolphins, salps and noble pen shell). A total of 1224 sightings were recorded, of which 530 referred to Mnemiopsis, followed by the scyphozoan jellyfish Rhizostoma pulmo (22%), Cotylorhiza tuberculata (11%) and Aurelia spp. (8%). avvistAPP produced data confirming the presence of Mnemiopsis (often in abundances &gt, 20 individuals m−2) along almost the entire Italian coast in the summer of 2019 and 2020.

The largest scyphozoan jellyfish of the Mediterranean Sea, Drymonema dalmatinum was first described by Haeckel [1] from material collected off the Dalmatian coast of the Adriatic Sea [...]

One of the obstacles to detecting regional trends in jellyfish populations is the lack of a defined baseline. In the Adriatic Sea, the jellyfish fauna (Scyphozoa and Ctenophora) is poorly studied compared to other taxa. Therefore, our goal was to collect and systematize all available data and provide a baseline for future studies. Here we present phenological data and relative abundances of jellyfish based on 2010–2019 scientific surveys and a “citizen science” sighting program along the eastern Adriatic. Inter-annual variability, seasonality and spatial distribution patterns of Scyphomedusae and Ctenophore species were described and compared with existing historical literature. Mass occurrences with a clear seasonal pattern and related to the geographical location were observed for meroplanktonic Scyphomedusae Aurelia solida, Rhizostoma pulmo, and to a lesser extent Chrysaora hysoscella, Cotylorhiza tuberculata and Discomedusa lobata. Holoplanktonic Pelagia noctiluca also formed large aggregations, which were seasonally less predictable and restricted to the central and southern Adriatic. Four species of Ctenophora produced blooms limited to a few areas: Bolinopsis vitrea, Leucothea multicornis, Cestum veneris and the non-native Mnemiopsis leidyi. However, differences between Adriatic subregions have become less pronounced since 2014. Our results suggest that gelatinous organisms are assuming an increasingly important role in the Adriatic ecosystem, which may alter the balance of the food web and lead to harmful and undesirable effects.

Jellyfish as food represent a millennial tradition in Asia. Recently, jellyfish have also been proposed as a valuable source of protein in Western countries. To identify health risks associated with the potential human consumption of jellyfish as food, trace element accumulation was assessed in the gonads and umbrella tissues of the Mediterranean Rhizostoma pulmo (Macri, 1778), sampled over a period of 16 months along the shallow coastal waters a short distance from the city of Taranto, an area affected by metallurgic and oil refinery sources of pollution. Higher tissue concentrations of trace elements were usually detected in gonads than in umbrella tissue. In particular, significant differences in the toxic metalloid As, and in the metals Mn, Mo, and Zn, were observed among different tissues. The concentrations of vanadium were slightly higher in umbrella tissues than in gonads. No positive correlation was observed between element concentration and jellyfish size, suggesting the lack of bioaccumulation processes. Moreover, toxic element concentrations in R. pulmo were found below the threshold levels for human consumption allowed by Australian, USA, and EU Food Regulations. These results corroborate the hypothesis that R. pulmo is a safe, potentially novel food source, even when jellyfish are harvested from coastal areas affected by anthropogenic impacts.

[Aim] Global anthropogenic changes have altered biogeography and phenology of marine populations, thereby promoting a spatial reconfiguration in the functioning of marine ecosystems. Among these changes, massive proliferations of jellyfish in temperate latitudes warn of potential alterations in biogeochemical fluxes, ecosystems’ structure and assets, and the services they provide to human welfare. Understanding driving factors shaping large-scale patterns of jellyfish proliferations is a pressing need in global ecology and sustainability science. Using a comprehensive dataset of the largest blooming scyphomedusae in southern European seas we test, over broad space–time scales, current hypotheses relating jellyfish dynamics to warming and eutrophication., [Location] Southern European seas., [Time period] 1875–2019., [Major taxa studied] Rhizostoma pulmo., [Methods] We have gathered historical and contemporaneous records of R. pulmo from the Mediterranean and Black Seas over the last two centuries (7,359 records). Generalized statistical models were used to assess the influence of thermal (latitudinal) and productivity (longitudinal) gradients on the biogeographical patterns, and the species’ phenology at large and regional scales., [Results] Rhizostoma pulmo abundance exhibited an enhanced magnitude and frequency in recent decades, concurrently with positive temperature anomalies. We found that the latitudinal temperature gradient, but not productivity, shaped long-term bloom intensity and biogeographical patterns of the species. Our analysis further uncovered a significant effect of the interannual variability of spring temperature on the species’ phenology over the period 2008–2018, with warmer springs favouring an earlier start (c. 3 months) and a longer duration (from 5 to 7 months) of jellyfish season., [Main conclusions] Among the current hypotheses linking jellyfish changes with anthropogenic disturbances, only the warming-based hypothesis gained support over wide space–time scales, while the eutrophication-based hypothesis mainly applied at local scales. Hence, biogeographical patterns of R. pulmo are shaped by the latitudinal temperature gradient, while the species bloom dynamics echo variations in ecoregion thermal regimes., This study was conducted as part of the Ph.D. dissertation of V.L. and was supported by the National Agency for Research and Innovation, Agencia Nacional de Investigación e Innovación (ANII), Uruguay (code POS_CFRA_2017_1_147109).

In recent decades, an increase in the abundance and frequency of bloom events has been reported for the scyphozoan Rhizostoma pulmo in the Mediterranean Sea. Understanding such events requires a thorough assessment of the species' population dynamics through environmental windows allowing species development. The semi-enclosed coastal lagoon of Bages Sigean, France (43 degrees 05 ' 12.72 '' N; 3 degrees 00 ' 35.3 '' E) offers an exceptional framework for investigating the population dynamics of the species, and how its growth rates and environmental niches vary over time. Three cohorts starting in April, May and June 2019 were identified, while the overall population growth reached the maximum biomass (10.2 g m(-3)) in July. Bell diameter and total length were identified as the best morphological proxies of biomass estimation. The abundances of the two most abundant copepods' species appear to drive R. pulmo's dynamics in the lagoon. Based on multinomial analysis and using the von Bertalanffy model, different growth rates for juveniles (4.7 and 2.4 mm day(-1)) and adults (1.8 and 0.9 mm day(-1)) were determined for the first two cohorts. Thermohaline niches varied during ontogeny, but also among populations in three coastal Mediterranean lagoons: Bages Sigean (France), Mar Menor (Spain) and Bizerte (Tunisia), shedding light on the metapopulation dynamics of R. pulmo inhabiting the Mediterranean Sea. The pressing need for understanding the dynamics of jellyfish abundances and their impacts on ecosystems, calls for increased efforts on monitoring these populations and their life history traits to parametrize and build reliable ecosystem models.

Marine parasites are an important but often neglected component of ecosystems. This is particularly true for cnidarian parasites and their life cycles; few evidences of trophic transmission of trematodes from jellyfish to fish have been reported. This context inspired our idea of investigating one of the most complex and diffused jellyfish in the Mediterranean Sea, Rhizostoma pulmo. This work is the first attempt to study Trematoda parasites in Adriatic scyphomedusae. The goals are to 1) determine prevalence and intensity of metacercariae in Rhizostoma pulmo, 2) identify the species involved through morphological and molecular analysis, 3) test whether infection parameters change in different body parts and in relation to jellyfish size. While waiting for molecular results, all parasites morphologically investigated potentially belonged to the genus Opechona. The total number of parasites varied between 18.7 ± 6.7 parasite per individual in 0-2 cm diameter jellyfish up to 510.2 ± 136.4 parasites in larger ones. The 100% of infected individuals suggests that R. pulmo is a true host of digenetic trematodes, at least for this Opechona sp., and therefore important for their life cycle in the region. This also supports the theory that fish predate on Rhizostoma p., since trophic interactions are necessary for this genus to complete their cycles. Parasitology may be another way to investigate fish-jellyfish predation, integrating methods like gut contents and stable isotopes analysis. Further aspects should be investigated such as the characterization of parasites life cycle, the differences between the scyphozoan species and the potential role of blooms as elevators for parasites towards the fish compartment.

Globalno segrevanje ozračja ustvarja pogoje, primerne za življenje meduz. Po vsem svetu prihaja do množičnih pojavljanj meduz oziroma tako imenovanega cvetenja. Slednje ima številne negativne vplive na človeka. Meduze povzročajo gospodarsko škodo na področju turizma, ribolova, ribogojstva in mašijo hladilne sisteme jedrskih elektrarn. Zaradi naštetih vzrokov se iščejo novi načini uporabe meduzne biomase. Veliko uporabnost kaže mukus meduz, ki je glikoproteinski polimer. V magistrskem delu smo proučevali mukus meduz Rhizostoma pulmo. Opisali smo njegove lastnosti in preverili možnost uporabe mukusa kot flokulanta v procesih čiščenja z mikroplastiko kontaminirane vode. Preverili smo tudi sposobnost vezave različnih vrst mikroplastike in dejavnikov, ki vplivajo na razgradnjo mukusa. Ugotovili smo, da ima mukus sposobnost vezave delcev polistirena. Ne veže pa delcev polietilena. Vezava delcev je povečala strukturiranost mukusa, kar se je odražalo v povečani viskoznosti. Kemijsko razgrajen mukus ni bil sposoben vezave delcev. Mukus pri naših pogojih gojenja ni bil mikrobno razgradljiv. Global warming creates conditions suitable for jellyfish life. Sudden blooms of great abundance are getting worldwide attention and have many negative effects on humans. They are causing economic damage in the fields of tourism, fishing, aquaculture, and nuclear plants. Jellyfish mucus, a glycoprotein polymer, has many biotechnological applications. In the master thesis we studied mucus of jellyfish Rhizostoma pulma. We described its properties and used mukus as a flocculant in the purification processes of water contaminated with microplastics. We tested its ability to bond to different types of microplastics and studied factors that influenced its degradation. We have found that mucus binds polystyrene particles. However, it did not bind polyethylene particles. Particle binding increased structure of the mucus, which was reflected in increased viscosity. Chemically degraded mucus was not capable of binding polystyrene particles. The mucus was not microbiologically degradable under our growing conditions.

Jellyfish have emerged as a source of next generation collagen that is an attractive alternative to existing sources, such as bovine and porcine, due to a plentiful supply and providing a safer source through lack of bovine spongiform encephalopathy (BSE) transmission risk and potential viral vectors, both of which could be transmitted to humans. Here we compare collagen implantable sponges derived for the first time from the Rhizostoma pulmo jellyfish. A further novelty for the research was that there was a comparison for sponges that were either uncrosslinked or crosslinked using 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride (EDC), and an assessment on how this affected resorption, as well as their biocompatibility compared to bovine type I collagen sponges. The scaffolds were prepared and examined using sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS PAGE) and scanning electron microscopy (SEM). The samples were implanted in adult male Wistar rats for in vivo experimentation. Both crosslinked and uncrosslinked jellyfish collagen sponges showed a significant reduction in histopathology scores over the course of the study, whereas the bovine collagen sponge scores were not significantly reduced. Both jellyfish collagen sponges and the bovine sponge were tolerated well by the hosts, and a recovery was visible in all samples, suggesting that R. pulmo jellyfish-derived collagen could offer compelling biocompatibility with wound healing applications. We also demonstrate that noncrosslinked samples could be safer with better resorption times than crosslinked samples. © 2017 The Authors Journal of Biomedical Materials Research Part B: Applied Biomaterials Published by Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 1524-1533, 2018.

Jellyfish blooms are frequent and widespread in coastal areas worldwide, often associated with significant ecological and socio-economic consequences. Recent studies have also suggested cnidarian jellyfish may act as vectors of bacterial pathogens. The scyphomedusa Rhizostoma pulmo is an outbreak-forming jellyfish widely occurring across the Mediterranean basin. Using combination of culture-based approaches and a high-throughput amplicon sequencing (HTS), and based on available knowledge on a warm-affinity jellyfish-associated microbiome, we compared the microbial community associated with R. pulmo adult jellyfish in the Gulf of Taranto (Ionian Sea) between summer (July 2016) and winter (February 2017) sampling periods. The jellyfish-associated microbiota was investigated in three distinct compartments, namely umbrella, oral arms, and the mucus secretion. Actinobacteria, Bacteroidetes, Chlamydiae, Cyanobacteria, Deinococcus-Thermus, Firmicutes, Fusobacteria, Planctomycetes, Proteobacteria, Rhodothermaeota, Spirochaetes, Tenericutes, and Thaumarchaeota were the phyla isolated from all the three R. pulmo compartments in the sampling times. In particular, the main genera Mycoplasma and Spiroplasma, belonging to the class Mollicutes (phylum Tenericutes), have been identified in all the three jellyfish compartments. The taxonomic microbial data were coupled with metabolic profiles resulting from the utilization of 31 different carbon sources by the BIOLOG Eco-Plate system. Microorganisms associated with mucus are characterized by great diversity. The counts of culturable heterotrophic bacteria and potential metabolic activities are also remarkable. Results are discussed in terms of R. pulmo ecology, the potential health hazard for marine and human life as well as the potential biotechnological applications related to the associated microbiome.

A fundamental structural component of extracellular matrix in all connective and interstitial tissue, collagen is the most abundant protein in the human body. To date, mammalian collagens sources represent the golden standard for multiple biomedical applications, while marine-derived collagens have largely been used in industry (food, pharmaceutical, and cosmetic), with little use in research and clinical applications. Herein we demonstrate the effective use Rhizostoma pulmo jellyfish collagen, a source of biocompatible, sustainable collagen for 2D and 3D cell culture, addressing the global drive for technological developments that result in the replacement of animals and their derived products in research. Jellyfish collagen harbors similar structural features mammalian collagen type I, despite differing slightly in amino acid content. Jellyfish collagen supports ovarian cancer (OvCa) cell line proliferation, cellular morphology and expression of epithelial to mesenchymal transition markers, supporting the use of R. pulmo as a non-mammalian collagen cell culture substrate. Furthermore, R. pulmo collagen is effective in 3D device fabrication such as sponges where it mimics tissue architecture complexity. OvCa cells migrated and differentiated within the R. pulmo collagen 3D scaffolds confirming its suitability for advanced cell culturing applications, providing an excellent alternative to mammalian collagen sources for the culture of human cells.

V rod Rhizostoma (Cuvier, 1788) združujemo vrste Rhizostoma pulmo (Macri, 1778), Rhizostoma octopus (Linnaeus, 1788) in Rhizostoma luteum (Quoy in Gaimard, 1827).Vse tri vrste imajo podobno telesno zgradbo in naseljujejo različna geografska območja, a zaradi prekrivanja taksonomskih znakov so obstoj in nedvoumni sorodstveni odnosi treh vrst še nerazjasnjeni. V nalogi smo razjasnili filogenetske odnose med vrstami v rodu Rhizostoma, filogenetsko strukturiranost populacij v Sredozemskem morju ter v kolikšni meri le te prihajajo v stik z Atlantskimi populacijami. V analizo smo vključili vzorce R. pulmo, ki so bili nabrani po celotnem Sredozemlju, vzorce R. luteum, nabrane ob obali Španije v Sredozemskem morju ter že obstoječe sekvence iz baze GenBank, ki pripadajo vrsti R. octopus. Rezultate smo pridobili s sekvenčnimi analizami nukleotidnih zaporedij. Pomnožili smo gene za 28S, ITS1 in ITS2, ki so na genomski DNK, ter COI z mitohondrijske DNK. Rezultate so predstavili v obliki filogenetskih dreves ter mrežne analize haplotipov. Analize so pokazale dobro podprto delitev rodu na tri vrste, kar je posledica biogeografskih dogajanj v preteklosti ter Almerijsko-Oranske fronte, ki delitve vzdržujejo. Poleg tega je razvidna tudi strukturiranost populacij vrste R. pulmo v Sredozemskem morju. Genus Rhizostoma is represented by the following species: Rhizostoma pulmo (Macri, 1778), Rhizostoma luteum (Quoy in Gaimard, 1827) and Rhizostoma octopus (Linnaeus, 1788). All three species are morphologically similar. The biggest difference among them is their geographic distribution. Because of small differences, dividing genus into three species is doubtfull according to some scientists. In this thesis we focused on clarification of genus phylogeny, phylogenetic structure of populations in Mediterranean Sea and their connection with Atlantic populations. In analysis samples of R. pulmo from Mediterranean Sea, R. luteum from Spanish coast and already sequenced samples of R. octopus from GenBank were used and compared. Target DNA segments were amplified with polymerase chain reaction. 28S, ITS1, ITS2 and COI regions were used in PCR. Results support division of genus Rhizostoma into three species which is the result of biogeographic events in the past and is maintained by Almeria-Oran front. Furthermore, Mediterranean populations are showing differences between populations from different locations.

The jellyfish Rhizostoma pulmo, Macr&igrave, 1778 (Cnidaria, Rhizostomae) undergoes recurrent outbreaks in the Mediterranean coastal waters, with large biomass populations representing a nuisance or damage for marine and maritime activities. A preliminary overview of the antioxidant activity (AA) of R. pulmo proteinaceous compounds is provided here based on the extraction and characterization of both soluble and insoluble membrane-fractioned proteins, the latter digested by sequential enzymatic hydrolyses with pepsin and collagenases. All jellyfish proteins showed significant AA, with low molecular weight (MW) proteins correlated with greater antioxidant activity. In particular, collagenase-hydrolysed collagen resulted in peptides with MW lower than 3 kDa, ranging 3&ndash, 10 kDa or 10&ndash, 30 kDa, with AA inversely proportional to MW. No cytotoxic effect was detected on cultured human keratinocytes (HEKa) in a range of protein concentration 0.05&ndash, 20 &mu, g/mL for all tested protein fractions except for soluble proteins higher than 30 kDa, likely containing the jellyfish venom compounds. Furthermore, hydrolyzed jellyfish collagen peptides showed a significantly higher AA and provided a greater protective effect against oxidative stress in HEKa than the hydrolyzed collagen peptides from vertebrates. Due to a high reproductive potential, jellyfish may represent a potential socioeconomic opportunity as a source of natural bioactive compounds, with far-reaching beneficial implications. Eventually, improvements in processing technology will promote the use of untapped marine biomasses in nutraceutical, cosmeceutical, and pharmaceutical fields, turning marine management problems into a more positive perspective.

Rhizostoma luteum was first described in 1827 by Quoy and Gaimard under the name Orythia lutea, based on nine specimens collected from the Strait of Gibraltar (southern Iberian Peninsula). After 60 years of no scientific records existing for this species, in 2013, a phylogenetic analysis confirmed that R. luteum differed from Rhizostoma pulmo and Rhizostoma octopus. In the present study, we report historical and recent records of living and stranded specimens of R. luteum since 1998. We reviewed historical accounts and photographic and videographic materials taken by citizens from the northeastern Atlantic Ocean and the Alboran Sea. Because of its similarity with the closely related Mediterranean R. pulmo, R. luteum was frequently misidentified in the Alboran Sea and, likewise, with another medusa from the order Rhizostomeae, Catostylus tagi, in the adjacent Atlantic Ocean coastal regions in the last two decades. The results of this investigation confirm the existence of the scyphomedusa R. luteum in the coastal waters of the west and south coasts of the Iberian Peninsula and west and north shores of Africa. Through a citizen science initiative and our own observations, we were able to confirm more than 150 observations of R. luteum over the past 17 years, demonstrating that this medusa is not such a rare species after all.

Blooms of jellyfishes are perceived to have increased during the last decades causing interference with human activities of both recreational and professional type. Those blooms seem to hold correlation with human impacts and environmental changes such as overfishing, the increase of temperature, eutrophication or habitat modification. In this study we perform the first simultaneous analysis of population dynamics from three scyphozoan jellyfishes, Aurelia sp. (Linnaeus, 1758), Cotylorhiza tuberculata (Macri, 1778) and Rhizostoma pulmo (Macri, 1778). The effect of temperature, salinity, ichthyoplankton, nutrients and chlorophyll a concentration have been studied. These three species are present in the Mar Menor coastal lagoon where they show a spatial and temporal segregation of their populations and life cycles that allows them to reduce interspecific competition. Temperature and its seasonal cycle have been determined to be a key factor regulating the populations, triggering the strobilation process either by an increase in temperature (C. tuberculata) or by a decrease in it (Aurelia sp.). Such segregation has a decisive effect on the ecosystem, since it allows a continuous temporal succession of top-down control on the lagoon trophic network.

Fishery, market and consumption of edible jellyfish are currently limited in western countries by the lack of market demand for jellyfish products and the absence of processing technologies adequate to the western market safety standards. The development of technology-driven processing protocols may be key to comply with rigorous food safety rules, overcome the lack of tradition and revert the neophobic perception of jellyfish as food. We show thermal treatment (100 °C, 10 min) can be used as a first stabilization step on three common Mediterranean jellyfish, the scyphomedusae Aurelia coerulea, Cotylorhiza tuberculata, Rhizostoma pulmo, differently affecting protein and phenolic contents of their main body parts. The antioxidant activity was assessed in thermally treated and untreated samples, as related to the functional and health value of the food. Heat treatment had mild effect on protein and phenolic contents and on antioxidant activity. The jellyfish Rhizostoma pulmo, showed the better performance after thermal treatment.