Over the last 50 years there has been an increased frequency and severity of negative impacts affecting marine fishery and aquaculture sectors, which claimed significant economic losses due to the ...interference of stinging gelatinous organisms with daily operational activities. Nevertheless, original scientific information on jellyfish-related incidents, their consequences, and potential preventative and mitigation countermeasures is limited and scattered across gray literature, governmental technical reports, and communication media. A literature scan searching for records of any interactions between jellyfish and the marine fishery/aquaculture sectors was carried out. Out of 553 papers, 90 contained original information, referring to more than 130 cases worldwide of negative impacts of jellyfish on marine fishery/aquaculture over the last century. Calling attention on too often neglected socio-economic and ecological impacts of jellyfish blooms, the purpose of this paper is to review and analyze the most up-to-date research on this subject and to provide a global perspective on the importance of jellyfish impacts and their cascading effects on marine fishery and aquaculture sectors.
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
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
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
compartments in the sampling times. In particular, the main genera
and
, 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
ecology, the potential health hazard for marine and human life as well as the potential biotechnological applications related to the associated microbiome.
Under future increased CO2 concentrations, seagrasses are predicted to perform better as a result of increased photosynthesis, but the effects in carbon balance and growth are unclear and remain ...unexplored for early life stages such as seedlings, which allow plant dispersal and provide the potential for adaptation under changing environmental conditions. Furthermore, the outcome of the concomitant biochemical changes in plant-herbivore interactions has been poorly studied, yet may have important implications in plant communities. In this study we determined the effects of experimental exposure to current and future predicted CO2 concentrations on the physiology, size and defense strategies against herbivory in the earliest life stage of the Mediterranean seagrass Posidonia oceanica. The photosynthetic performance of seedlings, assessed by fluorescence, improved under increased pCO2 conditions after 60 days, although these differences disappeared after 90 days. Furthermore, these plants exhibited bigger seeds and higher carbon storage in belowground tissues, having thus more resources to tolerate and recover from stressors. Of the several herbivory resistance traits measured, plants under high pCO2 conditions had a lower leaf N content but higher sucrose. These seedlings were preferred by herbivorous sea urchins in feeding trials, which could potentially counteract some of the positive effects observed.
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.
Jellyfish outbreaks in marine coastal areas represent an emergent problem worldwide, with negative consequences on human activities and ecosystem functioning. However, potential positive effects of ...jellyfish biomass proliferation may be envisaged as a natural source of bioactive compounds of pharmaceutical interest. We investigated the biochemical composition of mature female gonads and lysozyme antibacterial activity of oocytes in the Mediterranean barrel jellyfish
. Chemical characterization was performed by means of multinuclear and multidimensional NMR spectroscopy. The ovaries of
were mainly composed of water (93.7 ± 1.9% of wet weight), with organic matter (OM) and dry weight made respectively of proteins (761.76 ± 25.11 µg mg
and 45.7 ± 1.5%), lipids (192.17 ± 10.56 µg mg
and 9.6 ± 0.6%), and carbohydrates (59.66 ± 2.72 µg mg
and 3.7 ± 0.3%). The aqueous extract of
gonads contained free amino acids, organic acids, and derivatives; the lipid extract was composed of triglycerides (TG), polyunsaturated fatty acids (PUFAs), diunsaturated fatty acids (DUFAs), monounsaturated fatty acids (MUFAs), saturated fatty acids (SFAs), and minor components such as sterols and phospholipids. The
oocyte lysate exhibited an antibacterial lysozyme-like activity (mean diameter of lysis of 9.33 ± 0.32 mm corresponding to 1.21 mg/mL of hen egg-white lysozyme). The occurrence of defense molecules is a crucial mechanism to grant healthy development of mature eggs and fertilized embryos (and the reproductive success of the species) by preventing marine bacterial overgrowth. As a corollary, these results call for future investigations for an exploitation of
biomasses as a resource of bioactive metabolites of biotechnological importance including pharmaceuticals and nutrition.
Predicted pH decreases in ocean surface waters of ~0.3–0.5 and 0.7–0.8 pH units (for 2100 and 2300, respectively) are expected to negatively affect calcification processes and physiological ...performances of many marine organisms. Here we evaluated the response of important parameters such as growth, mortality, oxygen consumption, and mineralization of transplanted Pinna nobilis juveniles in the naturally acidified waters of a CO₂ vent system. Our field experiments show a general decrease of physiological responses of juveniles for the studied parameters along a decreasing pH gradient, even if significant effects are only observed under pH values of 7.6 units (“extreme” pH). In particular, the mortality rate increased from 10–30 % over the study period at control conditions to 60–70 % at extreme pH values. We conclude that near-future decreases in pH (decreases of 0.3–0.5 pH units) may not have a significant effect on performance of P. nobilis juveniles, while predicted longer-term decreases (decreases of 0.7–0.8 pH units) could affect the survival of the species. The combination of laboratory experiments with the assessment of naturally acidified environments can provide further insights into the threshold pH affecting the performance of vulnerable marine species.
Jellyfish represent an important component of marine food webs characterized by large fluctuations of population density, with the ability to abruptly form outbreaks, followed by rarity periods. In ...spite of considerable efforts to investigate how jellyfish populations are responding globally to anthropogenic change, available evidence still remains unclear. In the last 50 years, jellyfish are seemingly on the rise in a number of coastal areas, including the Mediterranean Sea, where jellyfish blooms periodically become an issue to marine and maritime human activities. Their impacts on marine organism welfare have been poorly quantified. The jellyfish, Rhizostoma pulmo, is an outbreak-forming scyphomedusa whose large populations spread across the Mediterranean, with increasing periodicity and variable abundance. Studies on cnidarian jellyfish suggested being important vectors of bacterial pathogens. In the present study, by combination of conventional culture-based methods and a high-throughput amplicon sequencing (HTS) approach, we characterized the diversity of the bacterial community associated with this jellyfish during their summer outbreak. Three distinct jellyfish compartments, namely umbrella, oral arms, and the mucus secretion obtained from whole specimens were screened for specifically associated microbiota. A total of 17 phyla, 30 classes, 73 orders, 146 families and 329 genera of microbial organisms were represented in R. pulmo samples with three major clades (i.e. Spiroplasma, Mycoplasma and Wolinella) representing over 90% of the retrieved total sequences. The taxonomic microbial inventory was then combined with metabolic profiling data obtained from the Biolog Eco-Plate system. Significant differences among the jellyfish compartments were detected in terms of bacterial abundance, diversity and metabolic utilization of 31 different carbon sources with the highest value of abundance and metabolic potential in the mucus secretion compared to the umbrella and oral arms. Results are discussed in the framework of the species ecology as well as the potential health hazard for marine organisms and humans.
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•Jellyfish-associated microbiota during a summer outbreak was characterized•Microbiota of three distinct jellyfish compartments was analyzed by culture-based and a high-throughput amplicon sequencing•Jellyfish blooms may represent vectors of potential bacterial pathogens•Jellyfish blooms may be a potential health hazard for marine organisms and humans
Low oxygen zones in coastal and open ecosystems have expanded in recent decades, a trend that will accelerate with climatic warming. Exposure of nearshore animals to hypoxic waters and increasing ...temperature may be stressful and lead to impaired physiological performance. Here, we evaluate the effect of low oxygen concentrations in interaction with increased temperature on juveniles of a large Mediterranean bivalve, Pinna nobilis. We examine the response of survival and oxygen consumption of juveniles placed in water with normal and low oxygen concentrations (100% and 40%, respectively) along an increased temperature gradient (24, 26, 28 and 30 °C) during 4 days. To our knowledge, this is the first study on hypoxia and its combined effect with temperature on juveniles of this species. We show that the two stressors alone or in combination do not influence the physiological performance of juveniles for short periods (4 days). This result stands apart from a general trend pointing at ocean warming as additional stressor that could increase the vulnerability of benthic macrofauna to reduced oxygen concentrations.
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.
In the course of this century, rising anthropogenic CO₂ emissions will likely cause a decrease in ocean pH, know as ocean acidification, together with an increase of water temperature. Only in the ...last years, studies have focused on synergetic effects of both stressors on marine invertebrates, particularly on early life stages considered more vulnerable. Disparate responses of their singular and combined effects were reported, highlighting the importance of extending the studies to different species and populations of marine invertebrates. Here, we observed the response of important parameters such as growth, mortality and oxygen consumption of juvenile pen shell Pinna nobilis at supplied pCO₂ gas levels of 400 ppm (ambient) and 1000 ppm and at three temperatures (20, 23 and 26 °C) during 36 days. To our knowledge, this is the first study on ocean acidification and temperature effects on juveniles of this species. We show that the two stressors play roles at distinct levels, with pCO₂ influencing growth and partially mortality, and temperature increasing mortality rates and oxygen consumption strongly. Therefore, juveniles of P. nobilis are more likely affected by increasing temperature than the pCO₂ levels expected by the end of the twenty-first century.
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