May Gómez Cabrera and Ted Packard took part in the 8th International Jellyfish Blooms Symposium (JBS8), held last week at the University College Cork campus (Ireland), presenting two scientific posters developed as part of the PHYSALI project
Researchers from the Ecophysiology and Physics of Marine Systems (EOMAR) group at the ECOAQUA University Institute of the University of Las Palmas de Gran Canaria (ULPGC) –May Gómez, the group’s director, and Ted Packard– took part in the most important international conference on jellyfish, the 8th International Jellyfish Blooms Symposium (JBS8), held between 29 June and 3 July at University College Cork (Ireland), presenting two of their studies carried out as part of the PHYSALIA project.
The researchers presented two scientific posters entitled ‘From polyp to medusa: compositional and metabolic evolution in Aurelia aurita’ and ‘Physalia, how do you conduct yourself?’. Both are the result of research being carried out as part of the ‘Evolution of Biological Sailing’ project, known by its acronym PHYSALIA, which aims to analyse the navigation patterns of Portuguese man-of-war, with the aim of understanding their evolution and, in doing so, improving predictions of their arrival on the coast.
May Gómez, researcher and director of EOMAR, at the conference on jellyfish held in Ireland, alongside the scientific posters presented by the ECOAQUA research group.
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Aurelia aurita (the common jellyfish) has a three-phase life cycle involving metamorphosis, progressing from sessile polyps to free-swimming ephyra and, finally, maturing into jellyfish. This metamorphic process is triggered by a drop in temperature.
The first of these papers (‘From polyp to medusa: compositional and metabolic evolution in Aurelia aurita’ –Romero?Kutzner V., Bondyale?Juez D.R., Martínez I., Herrera A., Packard T.T., Gómez M.) explores the complex changes in protein, lipid and carbohydrate content that occur during this process, examining alterations in respiratory and excretory metabolism using both physiological and enzymatic methodologies. This study provides the first monitoring of these parameters.
Observations at the compositional and metabolic levels were carried out over 108 days in triplicate, with three simultaneous cultures maintained under identical conditions throughout the experiment. The results reveal compositional changes, particularly in lipid content, one of the main sources of biological energy during metamorphosis.
Furthermore, during the transition from the strobila to the metaepheira stage, the water content increased from 89 per cent to 99 per cent over a period of 20 days. Respiratory activity was reduced by 76 per cent during the strobila stage, due to the necessary drop in temperature. At the same time, excretory activity showed a more gradual increase in ammonium excretion during the planktonic stages, once feeding had resumed. These findings may provide insights into the potential effects of future environmental changes across the entire life cycle.
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Researcher Ted Packard at the International Jellyfish Blooms Symposium held in Cork, alongside the scientific posters presented by the ECOAQUA research group.
Portuguese man-of-war
Meanwhile, ‘Physalia, how do you conduct yourself?’ (Martínez I., Cunill A., Huelbes S., Torres-Gómez A., Herrera A., Packard T.T., Gómez M.), in which, alongside researchers from EOMAR, Álvaro Torres-Gómez from the Aquaculture Research Group (GIA), aims to deepen our understanding of the physiology and biochemistry of the siphonophore Physalia physalis (Portuguese man-of-war).
To this end, the research team reared stranded specimens in 1,000-litre tanks with recirculating seawater for a period of between 7 and 15 days. In these tanks, the Physalia were fed with gilthead seabream (Sparus aurata) fry, and their weight and the characteristics of their pneumatophore and sail were assessed. At the end of this acclimatisation period, the Physalia physalis were carefully transported to the laboratory, where their respiratory parameters (RO?, RCO?) were measured. The specimens were then frozen at -80 ºC for subsequent enzymatic and biochemical analyses. The results obtained were compared with those of freshly collected (beached) specimens.
EOMAR researchers May Gómez and Ted Packard alongside other researchers participating in the conference held in Cork.
No significant changes were observed in the size of the pneumatophore or the sail during the monitoring period. The organisms appeared to be in good health under indoor conditions. Weight gain, in terms of wet weight (g), was not uniform. All individuals showed comparable values for both respiratory status (RO?, RCO?) and their potential relating to O? consumption (φ) and CO? production (ψ), as well as for biochemical composition (protein, carbohydrate and lipid content).
The RO? and RCO? values fell within the same range, whilst the value of ψ was an order of magnitude higher than that of φ. Differences were observed between cultured and freshly collected organisms in terms of stress-related enzyme activities (CAT, GST, SOD and LDH). These differences could indicate poor health when samples are collected from the beach (metabolic stress). Longer-term cultivation could reduce stress markers and offer a chance of recovery.
The aim of this important conference held in Ireland is to bring together researchers from around the world so that they can meet, interact and share the latest research advances on this topic, discuss issues, future scenarios and innovations in the field of research, inspire one another and develop collaborative networks.