Report

Teaser, summary, work performed and final results

Periodic Reporting for period 1 - PULMO (PULMO: Population dynamics, trophic interactions, and human exploitation of a novel nutraceutical and pharmaceutical marine resource: the Mediterranean sea lung jellyfish, Rhizostoma pulmo .)

Teaser

Marine jellyfish are recognized as subject to proliferations in many coastal areas, where their populations experience seasonal and inter-annual large fluctuations, characterized by sudden outbreaks alternate with rarity periods. When they are exceedingly abundant, jellyfish...

Summary

Marine jellyfish are recognized as subject to proliferations in many coastal areas, where their populations experience seasonal and inter-annual large fluctuations, characterized by sudden outbreaks alternate with rarity periods. When they are exceedingly abundant, jellyfish cause substantial ecological impacts on marine biodiversity, interfere with economic and recreational human activities, and may be harmful to public health. For these reasons, jellyfish “blooms” are regarded as a multi-billion Euro problem for human activities in the sea and coastal zones. Understanding of jellyfish biology and ecology is therefore mandatory to prevent or mitigate critical ecological and economic drawbacks related to massive proliferations of gelatinous organisms. Under a more positive perspective, the large amount of jellyfish biomass could be considered as an untapped source of bioactive compounds including peptides, collagen and gelatin, sugars, fatty acids, enzymes, calcium, water-soluble minerals, and biopolymers making them a potentially valuable material for industrial uses in cosmetic, pharmaceutical and biomedical industry as well as food or feed. PULMO aimed to investigate mechanisms of massive proliferations of one of the most common jellyfish in the Mediterranean Sea, Rhizostoma pulmo, and to assess its potential utilization as exploitable biomass for the development of a new sea-based bioeconomy. Overall objectives included: [I] gathering novel information about the biology, trophic ecology, biochemical and molecular composition of the jellyfish; [II] investigating key parameters of population dynamics and life history traits; [III] discovering the jellyfish-associated microbial diversity; [IV] assessing the potential for the exploitation of jellyfish-related biomaterials.

Work performed

PULMO was implemented in collaboration with several laboratories at the Universities of Salento (Lecce), Bari, Palermo, and the Taranto Institute for Coastal and Marine Enviroment. The research activity was split in workpackages, including a) comprehensive review of available literature on the species R. pulmo and other related taxa; b) sampling over a period of 18 months; c) investigation on different life stages; d) analysis of jellyfish population dynamics, reproductive biology and trophic ecology; e) analysis of diversity, abundance, and metabolic activities of jellyfish-associated microbial communities; e) analysis of biochemical composition and biological activities of jellyfish tissues. The literature review was carried out on near 100 scientific articles.This search allowed setting the available baseline information on species, to identify knowledge gaps preventing predictions on jellyfish demography in the Mediterranean Sea, and to define a comprehensive sampling plan, protocols, and methodologies for PULMO. Sampling was carried out on a single, resident jellyfish population in the Gulf of Taranto, Ionian Sea. Jellyfish specimens at different stage of development were collected in the field across months of the sampling period. All samples were processed in according to the adopted protocols for morphological, biochemical, and microbiological analyses. Each jellyfish sampling was integrated by the collection of chemico-physical environmental data, zooplankton and water samples. A quest for the so far unknown asexual polyp stage was carried out by expert scuba divers over a wide range of available artificial hard substrates occurring in the sampling area. Sand samples were transported to laboratory aquaria in thermostatic room in search of resting stages. Biological and water samples were distributed to different laboratories for analyses of stable isotopic, molecular taxonomy and metabolic profiling of the jellyfish-associated microbiome, and biochemical composition of jellyfish, including heavy metal contents. Morphological and histological analyses on jellyfish samples were carried out by microscopy work. The seasonal changes and the reproductive biology of R. pulmo population were monitored over the year with estimation of Gonad-Somatic and Fecundity Indexes.The seasonal reproductive cycle was followed by standard histological methods on semithin sections of the gonadic tissue. The combination of gut content and nitrogen and carbon stable isotope analyses were paralleled by an inventory of the coastal zooplankton prey community. Jellyfish associated microbial taxa isolated from different body fractions of adult jellyfish were identified by molecular taxonomy (16s rDNA) and metabolic activity screening. The biotechnological/pharmaceutical potential of R. pulmo has been investigated by integrated analysis of the anti-microbial activities of different fractions of jellyfish extracts and by the NMR spectroscopy characterization. The analysis of decay of jellyfish carcasses was not carried out because of the lack of time. Dissemination of results was carried out by participation to national and international conferences and by participation to expert meetings such as the International Jellyfish Bloom Symposium (Barcelona, June 2016, https://goo.gl/8RS97e) and the European Marine Biology Symposium (Piran, September, 2017 (https://goo.gl/gj48Cm) or the Unione Zoologica Italiana meeting (Torino, September, 2017) or by seminars to PhD students (Trieste, https://goo.gl/sMq3Up). PULMO has received attention by the public through high-impact daily news paper such as The New York Times (https://goo.gl/neBPwM), The Guardian (https://goo.gl/KL15rg§ù), Repubblica (https://goo.gl/LhqdNz) and popular science websites (https://goo.gl/WbvoTU, https://goo.gl/LBHKBr, https://goo.gl/WbvoTU).

Final results

PULMO has provided the opportunity to gather new knowledge on a marine organism with large, yet unexplored potential as key driver of Mediterranean coastal ecosystem functioning. Collaborative and cross-disciplinary research has been carried out and will continue in the near future to capitalize all new knowledge gathered by PULMO. The main expected result has been the collection of data providing new theoretical background to understand environmental and biological mechanisms boosting jellyfish blooms, provide in situ information to interpret the population dynamics and to assess the sustainable exploitation potential of jellyfish biomass into a Blue Growth perspective also in light of the sensitivity of jellyfish to ocean warming and their key trophic role in marine food webs. The high biomass reached by R. pulmo populations and their persistence in coastal areas and the gathered knowledge on the eco-physiological and reproductive optima of this species, strengthen the hypothesis of using R.pulmo biomasses as a sustainable resource for humans in many fields (e.g. pharmaceutics, nutraceutics and food resource). PULMO has boosted new knowledge that will be published into well-reputed scientific journals in the next months. A first short manuscript has been already published (Journal of Marine Microbiology), a first major article on jellyfish-related microbiome diversity and metabolic activities has been just completed and will be submitted to Frontiers in Microbiology, several others are in preparation dealing with a) analysis of trophic ecology; b) chemical composition and ecotoxicology; c) anti-microbial activity of compounds from jellyfish fractions; d) population dynamics and reproductive biology.