In recent decades, the global environmental balance has been disrupted due to new environmental conditions and increasing anthropogenic pressure. In this context, the increase in frequency and ...magnitude of jellyfish proliferation in the Mediterranean Sea can be examined as an indicator closely associated with potential impacts of global changes. Despite their importance in ecosystem function and services, current knowledge of jellyfish diversity and phenology is largely lacking in the southern Mediterranean Sea, particularly along the Moroccan Mediterranean coast. Rhizostoma pulmo is a large scyphozoan jellyfish endemic to the Mediterranean. It is the second dominant scyphozoan species in the jellyfish community of Al Hoceima Bay. In this article, we explore the seasonal dynamics of the jellyfish R. pulmo between the estuaries of Oued Ghis and Nekkour at Souani Beach. Due to the disparity between the visual abundance of jellyfish and their rare beaching along the shores of Al Hoceima Bay, we implemented a specific method for collecting R. pulmo . This approach involves the use of a coastal trawl, a fishing net 200 meters long with a mesh size of 5 cm, deployed 80 meters from the shore and pulled from both sides by fishermen. Sampling missions conducted throughout the year 2022 revealed that R. pulmo reaches its maximum abundance in summer. The results indicate a maximum abundance of 0.28 ind/m 2 in July 2022, with a maximum umbrella diameter reaching 26 cm in August 2022. Under the jellyfish umbrellas, fry of two fish species and one crustacean species were observed, adding an ecological dimension to this study.
Very little information is reported for parasites of cnidarians, therefore, the present work aimed to investigate parasitic infections in one of the most widespread jellyfish in the Mediterranean ...Sea, Rhizostoma pulmo. The goals were to determine prevalence and intensity of parasites in R. pulmo, identify the species involved through morphological and molecular analysis, test whether infection parameters differ in different body parts and in relation to jellyfish size. 58 individuals were collected, 100% of them infected with digenean metacercariae. Intensity varied between 18.7 ± 6.7 per individual in 0-2 cm diameter jellyfish up to 505 ± 50.6 in 14 cm ones. Morphological and molecular analyses suggest that the metacercariae belonged to the family Lepocreadiidae and could be possibly assigned to the genus Clavogalea. Prevalence values of 100% suggest that R. pulmo is an important intermediate host in the life cycle of lepocreadiids in the region. Our findings also support the hypothesis that R. pulmo is an important part in the diet of teleost fish, which are reported as definitive hosts of lepocreadiids, since trophic transmission is necessary for these parasites to complete their life cycles. Parasitological data may therefore be useful to investigate fish-jellyfish predation, integrating traditional methods such as gut contents analysis.
The Mediterranean basin is one of the regions heavily affected by jellyfish bloom phenomena, mainly due to the presence of scyphozoans, such as Rhizostoma pulmo. The jellyfish have few natural ...predators, and their bodies represent an organic-rich substrate that can support rapid bacterial growth with great impact on the structure of marine food webs. In Asiatic countries, jellyfish are widely studied for their health benefits, but their nutritional and nutraceutical values still remain poorly characterized. In this study, the differences in the 1H NMR spectroscopy metabolic profiles of R. pulmo female gonads and body fractions (including umbrella and oral arms), in different sampling periods, were studied. For each body compartment both lipid and aqueous extracts were characterized and their 1H NMR metabolic profiles subjected to multivariate analysis. From a statistical analysis of the extracts, a higher contents of ω-3 polyunsaturated fatty acids (PUFAs), amino acid and osmolytes (homarine, betaine, taurine) with important roles in marine invertebrates were observed in female gonads, whereas umbrella and oral arms showed similar metabolic profiles. These results support a sustainable exploitation of the jellyfish for the extraction of bioactive compounds useful in nutraceutical, nutricosmetics, and functional food fields.
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.
Scyphistomae show different modes of propagation, occasionally allowing the sudden release of great numbers of medusae through strobilation leading to so-called jellyfish blooms. Accordingly, factors ...regulating asexual reproduction strategies will control scyphistoma density, which, in turn, may influence blooming potential. We studied 11 scyphistoma species in 6 combinations of temperature and food supply to test the effects of these factors on asexual reproduction strategies and reproduction rates. Temperature and food availability increased reproduction rates for all species and observed reproduction modes. In all cases, starvation was the most important factor constraining the asexual reproduction of scyphistomae. Differences in scyphistoma density were found according to the reproductive strategy adopted by each species. Different Aurelia lineages and Sanderia malayensis presented a multi-mode strategy, developing up to 5 propagation modes. These species reached the highest densities, mostly through lateral budding and stolons. Cassiopea sp., Cephea cephea, Mastigias papua and Phyllorhiza punctata adopted a mono-mode reproductive strategy, developing only free-swimming buds. Lychnorhiza lucerna, Rhizostoma pulmo and Rhopilema esculentum also presented a mono-mode strategy, but they only developed podocysts. These 3 species had the lowest reproduction rates and polyp densities; not only their reproduction rates but also the need for a 2-fold set of environmental stimuli to produce new polyps (one for encystment, another for excystment) made this reproduction mode the slowest of those observed to be utilized for propagation. We conclude that blooms may be defined phylogenetically by the specific asexual modes each species develops, which, in turn, is regulated by environmental conditions.
The jellyfish
, Macrì 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
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 3⁻10 kDa or 10⁻30 kDa, with AA inversely proportional to MW. No cytotoxic effect was detected on cultured human keratinocytes (HEKa) in a range of protein concentration 0.05⁻20 μg/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.
The investigation of jellyfish gastrovascular systems mainly focused on stain injections and dissections, negatively affected by thickness and opacity of the mesoglea. Therefore, descriptions are ...incomplete and data about tridimensional structures are scarce. In this work, morphological and functional anatomy of the gastrovascular system of Rhizostoma pulmo (Macri 1778) was investigated in detail with innovative techniques: resin endocasts and 3D X-ray computed microtomography. The gastrovascular system consists of a series of branching canals ending with numerous openings within the frilled margins of the oral arms. Canals presented a peculiar double hemi-canal structure with a medial adhesion area which separates centrifugal and centripetal flows. The inward flow involves only the "mouth" openings on the internal wing of the oral arm and relative hemi-canals, while the outward flow involves only the two outermost wings' hemi-canals and relative "anal" openings on the external oral arm. The openings differentiation recalls the functional characteristics of a through-gut apparatus. We cannot define the gastrovascular system in Rhizostoma pulmo as a traditional through-gut, rather an example of adaptive convergence, that partially invalidates the paradigm of a single oral opening with both the uptake and excrete function.
Jellyfishes are considered a new potential resource in food, pharmaceutical and biomedical industries. In these latter cases, they are studied as source of active principles but are also exploited to ...produce marine collagen. In the present work, jellyfish skin polysaccharides (JSP) with glycosaminoglycan (GAG) features were extracted from Rhizostoma pulmo, a main blooming species of Mediterranean Sea, massively augmented by climate leaded “jellyfishication” of the sea. Two main fractions of R. pulmo JSP (RP-JSPs) were isolated and characterized, namely a neutral fraction (RP-JSP1) and a sulphate rich, negatively charged fraction (RP-JSP2). The two fractions have average molecular weights of 121 kDa and 590 kDa, respectively. Their sugar composition was evaluated through LC-MS analysis and the result confirmed the presence of typical GAG saccharides, such as glucose, galactose, glucosamine and galactosamine. Their use as promoters of wound healing was evaluated through in vitro scratch assay on murine fibroblast cell line (BALB/3T3 clone A31) and human keratinocytes (HaCaT). Both RP-JSPs demonstrated an effective confluency rate activity leading to 80% of scratch repair in two days, promoting both cell migration and proliferation. Additionally, RP-JSPs exerted a substantial protection from oxidative stress, resulting in improved viability of treated fibroblasts exposed to H2O2. The isolated GAG-like polysaccharides appear promising as functional component for biomedical skin treatments, as well as for future exploitation as pharmaceutical excipients.
Due to its unique properties, collagen is used in various emerging fields such as the pharmaceutical and biomedical device industries, as well as in related fields: nutraceuticals, cosmetics, food, ...beverages and nutritional supplements. Marine gelatin, one of the biomaterials involved in food and medicinal research, is denatured collagen produced from acid, alkaline, or enzyme hydrolysis. Gelatin is a crucial ingredient for the food, pharmaceutical, medical, biomedical focusing on versatile applications. Jellyfish collagen is a valuable resource for bioplastics and biomaterials used in various health sectors. Recently, marine organisms have been considered viable sources of collagen because they do not harbor transmissible diseases. In particular, fish biomass, as well as the catches of other types of organisms, such as small fish, jellyfish, starfish, sea urchins, sponges, possess a significant content of collagen. The collagen extracted from the species Rhizostoma pulmo from the Black Sea basin is also part of the bioresources that can be used to obtain natural marine collagen from this type of invertebrates. The use of discarded or hither to unused biomass could contribute to the development of a sustainable collagen extraction process with a positive impact on the ecosystem. In the future it is desired to approach a world strategy that minimizes the amount of waste and that supports all three general objectives of sustainability: sustainable economic well-being, social well-being and environmental protection.
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.
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