1. Why do only males of Mawia benovici (Pelagiidae: Semaeostomeae: Scyphozoa) seem to onhabit the Northern Adriatic seaValentina Tirelli, Tjaša Kogovšek, Manja Rogelja, Paolo Paliaga, Massimo Avian, Alenka Malej, 2021, other scientific articles Abstract: This manuscript presents four new observations of the jellyfish Mawia benovici in the Adriatic Sea. This new species was recently identified as Pelagia benovici by Piraino et al. (2014) and then placed in the new genus Mawia by Avian et al. 2016. This species is rare and is almost exclusively observed in the Adriatic Sea. Interestingly, the majority of observations refer to males only. Few studies have addressed the issue of sex determination in Syphozoa in particular, as sex identity can only be determined at the medusa stage. Unfortunately, the rarity of M. benovici and the lack of female specimens have so far prevented indispensable laboratory studies to clarify its life cycle. Still, we tried to propose an explanation for our field observations.
Keywords: jellyfish, sex ratio, Mediterranean Sea Published in DiRROS: 06.08.2024; Views: 92; Downloads: 73
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2. Jellyfish-associated microbiome in the marine environment : exploring its biotechnological potentialTinkara Tinta, Tjaša Kogovšek, Katja Klun, Alenka Malej, Gerhard J. Herndl, Valentina Turk, 2019, review article Abstract: Despite accumulating evidence of the importance of the jellyfish-associated microbiome to jellyfish, its potential relevance to blue biotechnology has only recently been recognized. In this review, we emphasize the biotechnological potential of host–microorganism systems and focus on gelatinous zooplankton as a host for the microbiome with biotechnological potential. The basic characteristics of jellyfish-associated microbial communities, the mechanisms underlying the jellyfish-microbe relationship, and the role/function of the jellyfish-associated microbiome and its biotechnological potential are reviewed. It appears that the jellyfish-associated microbiome is discrete from the microbial community in the ambient seawater, exhibiting a certain degree of specialization with some preferences for specific jellyfish taxa and for specific jellyfish populations, life stages, and body parts. In addition, different sampling approaches and methodologies to study the phylogenetic diversity of the jellyfish-associated microbiome are described and discussed. Finally, some general conclusions are drawn from the existing literature and future research directions are highlighted on the jellyfish-associated microbiome. Keywords: Cnidaria, Ctenophora, biodiversity, bioactive compounds, microbial communities, blue biotechnology Published in DiRROS: 06.08.2024; Views: 163; Downloads: 63
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3. Interannual size changes of adult Aurelia sp.5 medusae stage in the Marine protected Area of Mljet Island South AdriaticTjaša Kogovšek, Juan Carlos Molinero, Davor Lučić, Ivona Onofri, Barbara Gangai, Marijana Miloslavić, Delphine Bonnet, Alenka Malej, 2012, original scientific article Abstract: Aurelia aurita s.l. is the most widespread scyphozoan jellyfish that recurrently appear “en mass” and forms large aggregations mainly in coastal waters, embayments and estuaries. Beside anthropogenic factors controlling jellyfish populations climate change may play an important role. The aim of this study was to assess whether climate-related factors in absence of other anthropogenically induced stressor influence medusae size. We investigated seasonal and interannual changes in the size of Aurelia in a “jelly lake” in the National Park of Mljet Island (Croatia) where minimal human impact on the environment makes the Veliko Jezero a natural mesocosm for understanding the impact of climate change on the Aurelia population. The observed changes suggest Aurelia medusa population response to changing environment, in particular to enhanced temperature, by reduced body sizes. Comparison of Aurelia population dynamics from different regions in the Mediterranean Sea revealed the unique feature of the Veliko Jezero population. Despite the similarity of the environmental windows of medusae occurrences in the Veliko Jezero and regions in the Mediterranean Sea, medusae in the Veliko Jezero are present all year round. It seems that the lake bathymetry enables medusae to vertically migrate to deeper and cooler water layer, avoiding the limiting temperatures developed in the upper layer during the summer. These conditions may prolong the Aurelia medusae life span and together with continuous strobilation support the stability of the Aurelia medusae population all year round. Keywords: Mediterraneum, moon jellyfish, Adriatic Sea, South Adriatic Sea, marine lakes, Aurelia spp, climate-related factor, Mediterranean Sea, marine research, population dynamics Published in DiRROS: 05.08.2024; Views: 98; Downloads: 56
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4. The epiplankton community in the southern Adriatic: multiple trophic levels along the south - north and inshore-offshore gradientsValentina Turk, Davor Lučić, Jakica Njire, Senka Terzić, Tinkara Tinta, Adam Benović, Alenka Malej, 2012, original scientific article Abstract: The epiplankton community was investigated during Meduza cruises along south - north and offshore – inshore transects in the middle and southern Adriatic in spring 2002. The diel and vertical distribution of heterotrophic bacteria, phytoplankton pigment composition, micro- and mesozooplankton were assessed. At most stations we observed a thermocline at approximately 20 m and a prominent chlorophyll a peak at about 70 m depth. The integrated phytoplankton and bacterial biomass were lower at the station in the central part of the southern Adriatic, and increased gradually towards middle Adriatic and towards coastal stations. Vertical profiles of both bacterial abundance and production showed a distinct peak in the surface layer. Bacterial abundance was high also in the layer of the deep chlorophyll a maximum. Higher bacterial production was associated with elevated abundance of pico- and nanoplankton feeding zooplankton indicating that bacterial populations were generally controlled by predation. Keywords: Meduza project, heterotrophic bacteria, Adriatic Sea, South Adriatic Sea, phytoplankton pigments, open sea, microzooplankton, mesozooplankton, research cruises Published in DiRROS: 05.08.2024; Views: 107; Downloads: 50
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5. Signatures of pigments and processes in the south Adriatic Pit - project MEDUZAMira Morović, Vesna Flander-Putrle, Davor Lučić, Branka Grbec, Barbara Gangai, Alenka Malej, Frano Matić, 2012, original scientific article Abstract: During two cruises of the MEDUZA experiment conducted in July 2003 and May 2005 various data were obtained over the deepest part of the southern Adriatic Pit. Temperature, salinity, light transmission and fluorescence were measured in July 2003. During May 2005, except CTD measure- ments the samples were taken for laboratory determination of phytoplankton pigments with HPLC technique. During both cruises irradiance and radiance were measured at 14 wavelengths in the range 340-715 nm with optical probe to about 100 m depth. Bad weather conditions during both cruises caused interruption of measurements that continued after 24 to 48 hours. Stormy conditions have resulted in a slightly different structure of the water column. In the periods of measurements recorded were diurnal rhythms in a series of parameters, caused by solar radiation cycles in the surface layers as well as fluctuations in the deeper layers under the influence of the internal tide. Meteorological conditions and changes in sea level are also described. The analysis included the principal component and correlation analysis between the measured and derived parameters in order to establish a link between the in-situ pigments and multispectral data. During both cruises diurnal vertical oscillations were observed in biotic and abiotic parameters. Chlorophyll pigments prevailed over other pigments preventing other pigments to be distinguished spectrally. Regression models for chlorophyll a were established from radiance and reflectance ratios.
Keywords: termohaline properties, vertical migrations, Adriatic, South Adriatic Sea, diurnal rhithm, open sea, internal tide, Adriatic Published in DiRROS: 05.08.2024; Views: 207; Downloads: 166
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6. The lesser-known medusa Drymonema dalmatinum Haeckel 1880 (Scyphozoa, Discomedusae) in the Adriatic SeaAlenka Malej, Martin Vodopivec, Davor Lučić, Ivona Onofri, Branka Pestorić, 2014, original scientific article Abstract: Authors report historical and recent records of the little-known medusa Drymonema dalmatinum in the Adriatic
Sea. This large scyphomedusa, which may develop a bell diameter of more than 1 m, was fi rst described in 1880 by
Haeckel based on four specimens collected near the Dalmatian island Hvar. The paucity of this species records since
its description confi rms its rarity, however, in the last 15 years sightings of D. dalmatinum have been more frequent. Keywords: scyphomedusae, historical occurrence, recent observations, Adriatic Sea Published in DiRROS: 02.08.2024; Views: 113; Downloads: 68
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7. The occurrence of the jellyfish Aequorea cf. forskalea in the Adriatic Sea : comparison of historical and recent dataAlenka Malej, Davor Lučić, Natalia Bojanić, Martin Vodopivec, Paolo Paliaga, Branka Pestorić, Ivana Violić, Nastjenjka Supić, 2022, original scientific article Abstract: Jellyfish are becoming an increasingly important component of studies of the global marine environment, as their frequent mass phenomena affect ecosystem performance and have economic and health consequences. Recent research has focused primarily on mass occurrences of scyphozoans and ctenophores, while less attention has been paid to hydromedusae blooms, which can also have significant impacts on the marine ecosystem with economic consequences. Like many members of the Scyphozoa and Ctenophora, Aequorea species can be numerous and form blooms. Based on surveys from 2000 to 2020 and information provided by marine professionals, we examine the (multiannual) variability, seasonality, and spatial distribution patterns of the poorly studied temperate species Aequorea cf. forskalea (Hydrozoa: Leptothecata). We hypothesized that this macrogelatinous jellyfish with a bipartite life cycle (benthic polyps and planktonic medusae) is sensitive to seasonal and long-term temperature fluctuations, particularly because temperature has been shown to play a critical role in mediating transitions in the life cycle of cnidarians. The cold-water affinity of A. cf. forskalea was confirmed by a significant negative correlation with temperature and the most frequent occurrence during the winter-spring period. For the northern Adriatic (Gulf of Trieste), sea temperature data and semi-quantitative plankton data are available for the first decade of the 20th century, allowing comparison of the historical data (1900-1911) with our current data set. Compared to historical records, the current occurrence of A. cf. forskalea differs significantly. With the warming of the northern Adriatic Sea since the beginning of the 20th century, the current phenology of A. cf. forskalea has changed, probably related to the delayed production of medusae by hydroids in autumn, the absence of medusae in this season and their less frequent occurrence in winter. Keywords: hydromedusae, blooms, long-term monitoring, multiannual variability, Mediterranean Sea Published in DiRROS: 31.07.2024; Views: 268; Downloads: 109
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8. A MSFD complementary approach for the assessment of pressures, knowledge and data gaps in Southern European Seas: The PERSEUS experienceAlenka Malej, Alessandro Crise, H. Kaberi, J. Ruiz, 2015, original scientific article Abstract: PERSEUS project aims to identify the most relevant pressures exerted on the ecosystems of the Southern European Seas (SES), highlighting knowledge and data gaps that endanger the achievement of SES Good Environmental Status (GES) as mandated by the Marine Strategy Framework Directive (MSFD). A complementary approach has been adopted, by a meta-analysis of existing literature on pressure/impact/knowledge gaps summarized in tables related to the MSFD descriptors, discriminating open waters from coastal areas. A comparative assessment of the Initial Assessments (IAs) for five SES countries has been also independently performed. The comparison between meta-analysis results and IAs shows similarities for coastal areas only. Major knowledge gaps have been detected for the biodiversity, marine food web, marine litter and underwater noise descriptors. The meta-analysis also allowed the identification of additional research themes targeting research topics that are requested to the achievement of GES Keywords: morje, plankton, PERSEUS, MSFD, kvaliteta morskega okolja, evropske direktive, okoljski indikatorji, Marine Strategy Framework Directive, Southern European Seas, Good Environmental status, PERSEUS project, Initial assessment Published in DiRROS: 26.07.2024; Views: 128; Downloads: 99
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9. Who cares about ocean acidification in the Plasticene?Rachel Tiller, Francisco Arenas, Charles Galdies, Francisco Leitão, Alenka Malej, Beatriz Martinez Romera, Cosimo Solidoro, Robert Stojanov, Valentina Turk, Roberta Guerra, 2019, original scientific article Abstract: Plastics is all the rage, and mitigating marine litter is topping the agenda for nations pushing issues such as ocean acidification, or even climate change, away from the public consciousness. We are personally directly affected by plastics and charismatic megafauna is dying from it, and it is something that appears to be doable. So, who cares about the issue of ocean acidification anymore? We all should. The challenge is dual in the fact that is both invisible to the naked eye and therefore not felt like a pressing issue to the public, thereby not reaching the top of the agenda of policy makers; but also that it is framed in the climate change narrative of fear - whereby it instills in a fight-or-flight response in the public, resulting in their avoidance of the issue because they feel they are unable to take action that have results. In this article, we argue that the effective global environmental governance of ocean acidification, though critical to address, mitigate against and adapt to, is hindered by the both this lack of perception of urgency in the general public, fueled by a lack of media coverage, as well as a fight-or-flight response resulting from fear. We compare this to the more media friendly and plastics problem that is tangible and manageable. We report on a media plots of plastics and ocean acidification coverage over time and argue that the issue needs to be detangled from climate change and framed as its own issue to reach the agenda at a global level, making it manageable to assess and even care about for policy makers and the public alike? Keywords: oceans, acidification, plastics Published in DiRROS: 23.07.2024; Views: 95; Downloads: 51
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10. Bacteria associated with moon jellyfish during bloom and post-bloom periods in the Gulf of Trieste (northern Adriatic)Maja Kos Kramar, Tinkara Tinta, Davor Lučić, Alenka Malej, Valentina Turk, 2019, original scientific article Abstract: Jellyfish are a prominent component of the plankton community. They frequently form conspicuous blooms which may interfere with different human enterprises. Among the aspects that remain understudied are jellyfish associations with microorganisms having potentially important implications for organic matter cycling. To the best of our knowledge, this study is the first to investigate the bacterial community associated with live moon jellyfish (Aurelia solida, Scyohozoa) in the Adriatic Sea. Using 16S rRNA clone libraries and culture-based methods, we have analyzed the bacterial community composition of different body parts: the exumbrella surface, oral arms, and gastric cavity, and investigated possible differences in medusa-associated bacterial community structure at the time of the jellyfish population peak, and during the senescent phase at the end of bloom. Microbiota associated with moon jellyfish was different from ambient seawater bacterial assemblage and varied between different body parts. Betaproteobacteria (Burkholderia, Cupriavidus and Achromobacter) dominated community in the gastral cavity of medusa, while Alphaproteobacteria (Phaeobacter, Ruegeria) and Gammaproteobacteria (Stenotrophomonas, Alteromonas, Pseudoalteromonas and Vibrio) prevailed on ‘outer’ body parts. Bacterial community structure changed during senescent phase, at the end of the jellyfish bloom, showing an increased abundance of Gammaproteobacteria, exclusively Vibrio. The results of cultured bacterial isolates showed the dominance of Gammaproeteobacteria, especially Vibrio and Pseudoalteromonas in all body parts. Our results suggest that jellyfish associated bacterial community might have an important role for the host, and that anthropogenic pollution in the Gulf of Trieste might affect their community structure. Keywords: bacteria, moon jellyfish, Gulf of Trieste, Adriatic sea Published in DiRROS: 23.07.2024; Views: 125; Downloads: 114
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