Jellyfish is a compartment in the marine food web that often achieves high increases of biomass and that it is starting to be explored for several human potential uses. In this paper, a recently rediscovered large jellyfish, Rhizostoma luteum, is studied for the first time to describe its
organic compounds for the isolation and production of bioactive compounds in several fields of food, cosmetics, or biomedical industries. The biogeochemical composition (Carbon, Nitrogen and Sulfur content), protein and phenols content, together with their antioxidant activity, and the analysis oflipid content (identifying each of the fatty acids presented) was analyzed. The results presentedhere suggested this jellyfish has the highest antioxidant activity ever measured in a jellyfish, butalso with high content in polyunsaturated fatty acids (PUFAs), including the essential fatty acidlinoleic. The large natural biomass of Rhizostoma luteum in nature, the wide geographical spread,the fact that already its life cycle has been completed in captivity, establishes a promising positiveassociation of this giant jellyfish species and the isolation of bioactive compounds for future use in marine biotechnology., This research was funded by the Spanish Ministerio de Ciencia, Innovación y Universidades under grant number CTM2016-75487-R for the project MED2CA and the CSIC under grant number 2017301072. The research stay of R.L.V. was funded by Erasmus + Program, Peer reviewed

11 pages, 2 tables, 3 figures.-- This article is licensed under a Creative Commons Attribution 4.0 International
License, Seawater pH is undergoing a decreasing trend due to the absorption of atmospheric CO2, a
phenomenon known as ocean acidification (OA). Biogeochemical processes occurring naturally in the
ocean also change pH and hence, for an accurate assessment of OA, the contribution of the natural
component to the total pH variation must be quantified. In this work, we used 11 years (2005–2015)
of biogeochemical measurements collected at the Strait of Gibraltar to estimate decadal trends of
pH in two major Mediterranean water masses, the Western Mediterranean Deep Water (WMDW)
and the Levantine Intermediate Water (LIW) and assess the magnitude of natural and anthropogenic
components on the total pH change. The assessment was also performed in the North Atlantic Central
Water (NACW) feeding the Mediterranean Sea. Our analysis revealed a significant human impact on
all water masses in terms of accumulation of anthropogenic CO2. However, the decadal pH decline
found in the WMDW and the NACW was markedly affected by natural processes, which accounted for
by nearly 60% and 40% of the total pH decrease, respectively. The LIW did not exhibit a significant pH
temporal trend although data indicated natural and anthropogenic perturbations on its biogeochemical
signatures, Funding for this work was
provided by the European Commission through the projects CARBOOCEAN (FP6-511176), CARBOCHANGE
(FP7-264879), PERSEUS (FP7-287600) and COMFORT (H2020-820989) and by the Spanish Ministry of
Economy and Competitiveness (CTM2006-28141-E/MAR, CTM2016-75487-R). S.F acknowledges the financial
support of Canon Foundation in Europe Research Fellowships Program, Peer reviewed

[EN]: The Australian white-spotted jellyfish, Phyllorhiza punctata had not been previously recorded in the Northeast Atlantic Ocean. Here, we present the first record of this species in the southwestern Atlantic coast of Spain, Cadiz. Particularly, ten specimens including juveniles and adults were collected in August and October 2018 during five field surveys conducted in a tidal creek (Rio San Pedro), communicated with the Bay of Cadiz. The origin of the organism is unknown although long-distance transport of polyps attached to ship hulls or expansion of jellyfish aquarium exhibitions can be considered as possible pathways of invasion. Future observations are required to assess if P. punctata has established a stable population in the region., [FR]: Premier signalement de Phyllorhiza punctata (Cnidaria: Rhizostomae: Mastiglidae) dans l'océan Atlantique nord-est. La méduse australienne, Phyllorhiza punctata n'a encore jamais été signalée dans le nord- est de l'océan Atlantique. Nous présentons ici le premier signalement de l'espèce sur la côte atlantique au sud- ouest de l'Espagne, à Cadix. Dix spécimens, comprenant des juvéniles et des adultes, ont été trouvés en août et octobre 2018, lors de cinq échantillonnages dans le chenal de marée du Rio San Pedro, communiquant avec la Baie de Cadix. Le transport à longue distance de polypes attachés aux coques de navires ou l'augmentation d'expositions d'aquarium de méduses sont des voies possibles d'invasion. Des observations futures seront nécessaires afin de montrer si une population de cette méduse s'établira de façon pérenne dans ce nouvel habitat., The Spanish Ministerio de Ciencia, Innovación y Universidades funded this research under grant number CTM2016-75487-R for the project MED2CA.AEN was financially sustained by a PhD fellowship from the MED2CA project.

Ocean acidification and warming are challenging marine organisms and ecosystems around the world. The synergetic effects of these two climate change stressors on jellyfish remain still understudied. Here, we examine the independent and combined effects of these two environmental variables on polyp population dynamics of the Mediterranean jellyfish Cotylorhiza tuberculata. An experiment was conducted to examine asexual reproduction by budding and strobilation considering current and ca. 2100 winter (Trial 1, 36 days) and summer (Trial 2, 36 days) conditions under the RCP8.5 (IPCC 2013). In Trial 1, a temperature of 18°C and two pH levels (current: 7.9 and, reduced: 7.7) were tested. Trial 2 considered two temperature levels 24°C and 30°C, under current and reduced acidification conditions (8.0 and 7.7, respectively). Ephyrae size and statolith formation of released ephyrae from polyps exposed to summer temperatures under both acidification treatment was also analyzed. Zooxanthellae density inside the polyps throughout the experiment was measured. C. tuberculata polyps could cope with the conditions mimicked in all experimental treatments and no significant effect of pH, temperature, or the combination of both variables on the abundance of polyps was observed. At 18°C, strobilation was reduced under high PCO2 conditions. Under summer treatments (24°C and 30°C), percentage strobilation was very low and several released ephyrae suffered malformations and reduced size, as a consequence of reduced pH and elevated temperatures, separately. The number of statoliths was not affected by pH or temperature, however, bigger statoliths were formed at elevated temperatures (30°C). Finally, zooxanthellae density was not affected by experimental conditions, even if, the duration of the experiment significantly affected symbiont concentration. Our results show that even though polyps of C. tuberculata would thrive the future worst scenario predicted for the Mediterranean Sea, their capacity to undergo a proper strobilation and to produce healthy ephyrae will be more vulnerable to climate induced environmental conditions, thereby affecting medusae recruitment and, therefore, population dynamics of the species., This work was funded by the Spanish Ministerio de Ciencia, Innovación y Universidades (https://www.ciencia.gob.es) under grant number CTM2016-75487-R for the project MED2CA. AEN was financially sustained by a Ph.D. fellowship from the MED2CA project (https://med2ca.csic.es). This work is a contribution to the CSIC interdisciplinary thematic platform, WATER:iOS and the Project Agreement "Sistema de Observación y Predicción de Medusas en el Mar Balear” among Govern des Illes Balears, SOCIB and CSIC.

Ocean warming and acidification negatively affect organisms and biogeochemical cycles. To date, emphasis has been placed on the study of the impact on the structures of calcifying species; however, there is limited knowledge about the influence of the increase of these two variables on the solid structures of non-calcifying species as jellyfish. Here, we study the effects that the increase of temperature and acidity would cause on the statoliths of newly released ephyrae of the Mediterranean jellyfish Rhizostoma pulmo. Six combinations of temperature and PCO2 (18, 24 and 30 °C with a PCO2 of 500 and 1000 ppm each), according to the projections of the SSP5-8.5 (IPCC, 2021) scenario for the year 2100, were applied during 32 days to different groups of polyps randomly selected. Statoliths of the released ephyrae were counted and their size was measured. Our results show that, even though neither temperature nor PCO2 increase exerted a representative effect on the amount of statoliths synthesized in newly released ephyra from R. pulmo, it did exert an impact on the size of these structures: warming led to the formation of larger statoliths, while the rise in PCO2 induced the production of smaller structures. Under the simultaneous increase of both variables, acidification attenuated the effects of temperature, but still slightly larger statoliths were synthesized. The size differences observed in these structures could negatively impact the equilibrium system of this jellyfish species, potentially affecting its ability to survive., This research was funded by the Spanish Ministerio de Economía y Competitividad (grant number CTM 2016-75487-R “Respuesta de medusas mediterráneas al efecto interactivo de motores climáticos de impacto: supervivencia en un Mediterráneo más cálido y ácido”, project MED2CA), CSIC (grant number 202330E57 “Estudio de los efectos de motores de impacto del cambio climático sobre las dinámicas poblacionales de medusas mediterráneas”) and the Project Agreement “Detección de medusas en el mar Balear y su relación con las condiciones ambientales: hacia el desarrollo de un sistema de predicción pre-operacional” among Govern des Illes Balears, SOCIB and CSIC (Disposición 15052 del BOE núm. 310 de 2020). It was also financially sustained by a Ph.D. fellowship (FPU22/03487) from the Spanish Ministerio de Ciencia, Innovación y Universidades., Peer reviewed

Ocean warming and acidification negatively affect organisms and biogeochemical cycles. To date, emphasis has been placed on the study of the impact on the structures of calcifying species; however, there is limited knowledge about the influence of the increase of these two variables on the solid structures of non-calcifying species as jellyfish. Here, we study the effects that the increase of temperature and acidity would cause on the statoliths of newly released ephyrae of the Mediterranean jellyfish Rhizostoma pulmo. Six combinations of temperature and PCO2 (18, 24 and 30 °C with a PCO2 of 500 and 1000 ppm each), according to the projections of the SSP5-8.5 (IPCC, 2021) scenario for the year 2100, were applied during 32 days to different groups of polyps randomly selected. Statoliths of the released ephyrae were counted and their size was measured. Our results show that, even though neither temperature nor PCO2 increase exerted a representative effect on the amount of statoliths synthesized in newly released ephyra from R. pulmo, it did exert an impact on the size of these structures: warming led to the formation of larger statoliths, while the rise in PCO2 induced the production of smaller structures. Under the simultaneous increase of both variables, acidification attenuated the effects of temperature, but still slightly larger statoliths were synthesized. The size differences observed in these structures could negatively impact the equilibrium system of this jellyfish species, potentially affecting its ability to survive.

Jellyfish is a compartment in the marine food web that often achieves high increases of
biomass and that it is starting to be explored for several human potential uses. In this paper, a
recently rediscovered large jellyfish, Rhizostoma luteum, is studied for the first time to describe its
organic compounds for the isolation and production of bioactive compounds in several fields of food,
cosmetics, or biomedical industries. The biogeochemical composition (Carbon, Nitrogen and Sulfur
content), protein and phenols content, together with their antioxidant activity, and the analysis of
lipid content (identifying each of the fatty acids presented) was analyzed. The results presented
here suggested this jellyfish has the highest antioxidant activity ever measured in a jellyfish, but
also with high content in polyunsaturated fatty acids (PUFAs), including the essential fatty acid
linoleic. The large natural biomass of Rhizostoma luteum in nature, the wide geographical spread,
the fact that already its life cycle has been completed in captivity, establishes a promising positive
association of this giant jellyfish species and the isolation of bioactive compounds for future use in
marine biotechnology.