Alenka Malej

• Professor
• Senior Researcher at National Institute of Biology

The mauve stinger Pelagia noctiluca is a holoplanktonic oceanic jellyfish known for its painful sting and large outbreaks at irregular intervals. As jellyfish field observations are almost exclusively limited to coastal regions, there are many unknowns about the spatial and temporal dynamics of most species. We approach the problem using a spatiall...

The diet of the invasive ctenophore Mnemiopsis leidyi in the Gulf of Trieste was examined during its peak occurrence in the summer and early-autumn months (July to October) from 2017 to 2019, through the analysis of stomach contents. Altogether 506 specimens were individually caught for the analysis. A total of 3215 prey items were isolated and ide...

High abundances of gelatinous zooplankton (GZ) can significantly impact marine ecosystem by acting as both sink and source of organic matter (OM) and nutrients. The decay of GZ bloom can introduce significant amount of OM to the ocean interior, with its variability influenced by GZ life traits and environmental factors, impacting microbial communit...

The holoplanktonic scyphozoan Pelagia noctiluca, has attracted attention in the Mediterranean Sea due to its recurrent bloom events and significant ecological and economic impacts. Holoplanktonic medusozoans are thought to have evolved greater tolerance to various environmental factors, allowing them to thrive in open ocean and nearshore environmen...

Despite the progress in the international and regional governance efforts at the level of climate change, ocean acidification (OA) remains a global problem with profoundly negative environmental, social, and economical consequences. This requires extensive mitigation and adaptation effective strategies that are hindered by current shortcomings of g...

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...

While phytoplankton has been shown to influence climate in diverse ways, this review treats just two aspects: reduction of sea-air fluxes, and increase in ocean foam coverage. Plankton and neuston algae produce dissolved organic matter (DOM), which tends to concentrate in the sea-surface microlayer (SML). Fluxes of matter and energy exchange across...

In the Mediterranean Sea, the Strait of Messina (MS) is a very peculiar area, connecting highly different regions and representing a privileged observatory for an early comprehension and assessment of ecosystems shifts. It is hypothesized that the outbreaks observed near the coast of many sites in the Mediterranean Sea may be the result of transpor...

Symbiotic scyphozoan jellyfish are poorly understood in terms of their symbionts and traits, as well as the ecological significance of this association. Dinoflagellate symbionts of the medusae Cotylorhiza tuberculata, Phyllorhiza punctata, and Cassiopea xamachana collected in the Mediterranean Sea and Cabo Frio (Rio de Janeiro, Brazil) were phyloge...

Oceans, lakes and sewage treatment plants all contain water suspending a biota dominated by bacteria and the organic matter (OM) they secrete following expression of their genes. This OM regulates electrical layers at cell and molecule surfaces as well as rheological properties in the inter-cellular medium. OM also affects processes such as adsorpt...

The photosymbiosis with host-specific dinoflagellates is a widespread relationship in marine organisms. Despite the evidenced biodiversity of this kind of mutualism, most research focuses on the study of scleractinian corals, and there is a lack of knowledge about other symbiotic cnidarians such as jellyfishes. The Mediterranean jellyfish Cotylorhi...

While phytoplankton has been shown to influence climate in diverse ways, this review treats just two aspects: reduction of sea-air fluxes, and increase in ocean foam coverage. Plankton and neuston algae produce dissolved organic matter (DOM), which tends to concentrate in the sea-surface microlayer (SML). Fluxes of matter and energy exchange across...

Plankton and neuston microbes produce organic matter (OM), which accumulates in the sea surface microlayer (SML). Fluxes of heat and momentum exchange across the sea-air interface, as do fluxes of matter, including greenhouse gases, aerosols, microbes (algae, bacteria sensu lato and viruses) and other substances. At least at calm to moderate windsp...

Prikazan je kratek pregled dosedanjega znanja o karbonatnem ravnotežju severnega Jadrana, ki je dobro pufran zaradi dotoka karbonata z rekami alpskega in kraškega izvora in s tem omejenemu »kisanju«. V prihodnosti napovedujemo še vedno uravnoteženost s povečanim raztapljanjem CO2. V plitvih evtrofnih obalnih vodah bo lahko povezan vpliv povečanja a...

Mucilage-associated suspended matter in the Gulf of Trieste has been quantified using different approaches during the 2000 event. Remote sensing, video recording and image analysis were used to assess the quantity of surfaced mucilage. The quantity of water column mucilage was estimated taking quantitative samples of mucilage using a peristaltic pu...

The surface structures and mucus layers that form an interface between the epithelial layer of organisms and their external environment were studied in the bloom-forming moon jellyfish (Aurelia solida, Scyphozoa) from the northern Adriatic. The surface of the polyps revealed epithelial ciliated cells and numerous nematocysts, both non-discharged an...

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 majorit...

One of the obstacles to detecting regional trends in jellyfish populations is the lack of a defined baseline. In the Adriatic Sea, the jellyfish fauna (Scyphozoa and Ctenophora) is poorly studied compared to other taxa. Therefore, our goal was to collect and systematize all available data and provide a baseline for future studies. Here we present p...

A new book explores how two river-dominated coastal estuaries are responding to the pressures of human expansion and climate change.

Sustainable development depends on the provision of multiple marine ecosystem regulatory and provisional services (e.g., seafood, pharmaceuticals, climate regulation, maintenance of water quality, protection against coastal erosion and storm surge, ecotourism) which in turn depend on the status of ecosystem supporting services or natural capital (e...

Mesozooplankton and gelatinous zooplankton communities in Chesapeake Bay (CB) and the northern Adriatic Sea (NAS) have been subject to similar stressors over recent decades, including warming waters, overfishing, urbanization, and eutrophication. Direct comparisons between the systems are clouded by the lack of standardized and sustained long‐term...

Anthropogenic pressures of excess nutrient enrichment, overfishing, ocean warming, acidification, sea‐level rise, and acceleration of the water cycle converge on coastal ecosystems, where they act synergistically and threaten the capacity of coastal ecosystems to support services valued by society. Due to differences in geomorphology and circulatio...

Predstavljena je vsebina knjige v tisku pri založbi AGU-Wiley z naslovom »Obalni ekosistemi na prehodu: Primerjalna analiza severnega Jadrana in Zaliva Chesapeake« urednikov T. Maloneja, A. Malej in J. Faganelija. Knjiga prinaša primerjavo ekosistemov severnega Jadrana in Zaliva Chesapeake (vzhodna obala ZDA) in širi znanje o antropogenih vplivih n...

Ocean acidification (OA) is a global problem with profoundly negative environmental, social and economic consequences. From a governance perspective, there is a need to ensure a coordinated effort to directly address it. This study reviews 90 legislative documents from 17 countries from the European Economic Area (EEA) and the UK that primarily bor...

Fish farm-originating organic matter can modify the ecological processes in a benthic ecosystem. This was investigated in the sediments of the northern Adriatic Sea by measuring δ¹³C signature of nematodes, harpacticoids, and sedimentary organic matter, and by assessing pore water nutrients and bacterial composition. In a mesocosm experiment, ¹³C-l...

The issue of irregular massive plankton events is characterised by rather high scientific uncertainty mainly due to multiple linkages between causes and effects, but also to lack of evidence and to our inability to monitor these events at proper spatial and temporal scales. Many scales of variability that make definition of "regularity" rather diff...

Massive amounts of mucilage aggregates have been observed in different marine environments worldwide but the northern Adriatic seems to be most severily affected. Our observations indicated that the phenomenon passed through a characteristic "life cycle" and variable phytoplankton composition assessed by pigment biomarkers (HPLC). The number of phy...

Chemical composition of the Rotifer (Brachionus plicatilis, Muller) fed on Brachiomonas sp. and Eunotia sp. M. CARIC , B. SKARAMUCA and J. SANKO-NIJRE Biological Institute, P.O. Box 39, Dubrovnik (Yugoslavia) AB a live fo<Jd, rotifer (Brachionus plicatilis Muller) is well-suited to the purpose of rearin!! the larvae of most marine fish, due to its...

Abstract Harmful invader ctenophore Mnemiopsis leidyi's expansions in the Eurasian Seas, its spatio-temporal population dynamics depending on environmental conditions in recipient habitats have been synthesized. M. leidyi found suitable temperature, salinity and productivity conditions in the temperate and subtropical environments of the semi-enc...

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 abou...

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 biotechn...

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, thi...

Composition of 16S rRNA gene clone libraries (% of clones) from samples of jellyfish exumbrella (AK), oral arms (AR), and mucus from gastral cavity (AG) and seawater samples (W) at 5m depth collected on May and June 2011 in the Gulf of Trieste. Classification of bacterial clones was done down to the family level. The contribution of distinct bacter...

Bacterial isolates obtained from samples of jellyfish exumbrella (AK) and mucus from gastral cavity (AG) and seawater samples (W) at 5 m depth collected on May and June 2011 in the Gulf of Trieste. Classification of bacterial isolates was done down to the genus level. The contribution of distinct bacterial taxa is expressed as a percentage of the t...

Bacterial 16S rRNA sequences obtained from DGGE bands from jellyfish samples with their accession numbers. In the table is the name and an accession number of their closest relative in GeneBank (NCBI) with % of similarity, family, taxon, and isolation source. (PDF)

DGGE profile of bacterial 16S rRNA gene fragments of samples from Aurelia jellyfish exumbrella surface, oral arms, and mucus from gastral cavity. AK1, AK2: exumbrella surface of jellyfish collected in May; AK6, AK7: the exumbrella surface of jellyfish collected in June; AR1: sample of oral arms of jellyfish collected in May; AR6: the oral arms of j...

PCR reaction mix composition and PCR temperature cycling conditions. (PDF)

Similarities percentage (SIMPER) analysis of 16S rRNA gene clone libraries from samples of jellyfish exumbrella (AK), oral arms (AR), and mucus from gastral cavity (AG) and seawater samples (W) collected on May and June 2011 in the Gulf of Trieste. (PDF)

Similarities percentage (SIMPER) analysis of culturable fraction of bacterial community associated with jellyfish at the time of population peak and at the end of the bloom in the Gulf of Trieste. Group May includes samples of jellyfish exumbrella surface (AK1, AK3, AK6) and gastral cavity (AG1, AG6) collected in May. Group June includes samples of...

Detailed description of DNA extraction methods, with modifications. (PDF)

Similarities percentage (SIMPER) analysis of culturable fraction of the bacterial community associated with jellyfish exumbrella (AK), mucus from gastral cavity (AG) and seawater (W) collected in May and June 2011 in the Gulf of Trieste. (PDF)

The diversity indices S, H’, d, J’, Chao- 1 and library coverage’s (C) describing composition of total bacterial community associated with jellyfish exumbrella (AK), oral arms (AR) and mucus from gastral cavity (AG) and seawater (W) collected in May and June 2011 in the Gulf of Trieste. S represents the number of distinct bacterial taxa detected in...

The diversity indices S, H’, d, J’, describing composition of culturable fraction of bacterial community associated with jellyfish exumbrella (AK) and mucus from gastral cavity (AG) and seawater (W) collected in May and June 2011 in the Gulf of Trieste. S represents the number of distinct bacterial taxa detected in each sample. (PDF)

Manual annotation and counting of entities in underwater photographs is common in many branches of marine biology. With a marked increase of jellyfish populations worldwide, understanding the dynamics of the polyp (scyphistoma) stage of their life-cycle is becoming increasingly important. In-situ studies of polyp population dynamics are scarce due...

This study is the first to investigate bacterial community associated with live medusa Aurelia sp. in the Gulf of Trieste (northern Adriatic Sea) using both culture independent and culture-based methods. We have analysed bacterial community composition of different body parts of medusa: exumbrella surface, oral arms ('outer' body parts) and of gast...

https://presentations.copernicus.org/EGU2018-7675_presentation.pdf

A prominent increase in the moon jellyfish (genus Aurelia) populations has been observed since 1980 in two semi-enclosed temperate seas: the northern Adriatic Sea and the Inland Sea of Japan. Therefore, we reviewed long-term environmental and biotic data from the two Long-Term Ecological Research (LTER) sites, along with the increase in the moon je...

The benthic polyps are important in jellyfish outbreaks, which seem to have become more intense and are causing increasing problems to humans. We studied annual and seasonal changes of the moon jellyfish, Aurelia aurita s.l., polyp population dynamics in situ. Over three years, we took monthly photographs to quantify the abundance and occurrence of...

We have studied the influence of offshore marine constructions on the moon jellyfish population in the Adriatic sea, where the newly set up substrates enable the formation of a new population based in the formerly unpopulated open waters. Our five-year long computer simulation uses a high resolution coupled bio-physical individual-based model to tr...

Mnemiopsis leidyi has successfully made the transition from its native spatial range along the Atlantic coast of North and South America to many areas of the Eurasian seas. In summer 2016, we observed M. leidyi at several sites within the northern Adriatic (Mediterranean Sea). Here we describe the spatio-temporal distribution of this invasive cteno...

This study provides new and additional data on morphology and a phylogenetic analysis of the recently described species Pelagia benovici Piraino, Aglieri, Scorrano & Boero, 2014 from the Northern Adriatic (Mediterranean Sea). Comprehensive morphological analyses of diagnostic characters, of which the most significant are marginal tentacles anatomy,...

Aurelia spp. are cosmopolitan scyphozoan species and probably the most studied jellyfish in the world. They inhabit nearshore waters, especially closed basins, such as coastal embayments, fjords and estuaries, occupying a great variety of habitats worldwide. Recent studies have addressed the biogeography of the genus Aurelia and reported that it co...

Jellyfish swarms in the Southern European Seas (SES: Mediterranean and Black Seas) are a recurrent phenomenon which is attracting a groundswell of scientific and societal interest, with potential repercussions for public health, recreation, tourism, fisheries, aquaculture and marine ecosystem health. But this phenomenon also occurs in other areas o...

The increasing pressure from anthropogenic disturbances that are currently disrupting the natural balance of the Mediterranean marine ecosystems may lead to more frequent and more pronounced jellyfish outbreaks/blooms. High jellyfish abundances that occur in the Mediterranean Sea have negative consequences for human welfare. It is therefore, necess...

Aurelia aurita s.l. scyphistomae are capable of developing different asexual modes for propagation and thus present a multi-mode reproductive strategy. The reproduction rates and the reproductive strategy they adopt depend on a combination of various environmental parameters. We investigated the A. aurita s.l. polyp-to-polyp reproduction strategy a...

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-anal...

Scyphomedusae (Phylum Cnidaria, Class Scyphozoa) are perceived as a nuisance due to their sudden outbreaks that negatively affect human activities (particularly tourism and fisheries) mainly because of their stings. A brief review of the history of scyphozoan blooms in the Mediterranean and updated information available after 2010 point to an incre...

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 descrip...

Jellyfish play a key role in many pelagic ecosystems, especially in areas of extensive bloom events. In order to understand their role in pelagic food webs and in biogeochemical cycling, the energy stored and the trophic level occupied by jellyfish need to be quantified. To date, the common protocols applied for quantifying jellyfish biomass and an...

Not so long ago medusae were considered a trophic dead-end and a pest to humans while recently it has become increasingly clear that they may play a significant role in the pelagic food web and may also be a valuable resource to humans. Our contribution will highlight the double role medusae play as they present both opportunities and challenges fo...

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 first described in 1880 by Haeckel based on four specimens collected near the Dalmatian island Hvar. The paucity of this species records since its descript...

In this work a new methodology is proposed for predicting dispersion of biological species. The methodology uses multi level spatial-temporal association rules and directed graphs. The latter are the basis of Markov models which help us predict the spatial distribution of species, depending on previous observations. We applied the methodology on re...

Veliko Jezero (Mljet, Croatia) is a nearly enclosed karstic depression filled with saltwater, where jellyfish and prey exchange with the Adriatic Sea is negligible, making this small ecosystem ideal for the controlled study of medusae in food webs. Based on the analysis of their gut contents, medusae appeared to ingest less carbon than expected on...

The interdependence between the economy and the environment is becoming a fact of increasing importance. Productive coastal areas have been recognised as one of the most valuable ecosystems from an ecological and socio-economic point of view. In this paper we focus on the massive presence of jellyfish in the northern Adriatic and their effect on th...

Jellyfish (Cnidaria, Scyphozoa) blooms appear to be increasing in both intensity and frequency in many coastal areas worldwide, due to multiple hypothesized anthropogenic stressors. Here, we propose that the proliferation of artificial structures — associated with (1) the exponential growth in shipping, aquaculture, and other coastal industries, an...

Descripition of an ongoing project focused on monitoring jellyfish abundance from the coast.

A perceived recent increase in global jellyfish abundance has been portrayed as a symptom of degraded oceans. This perception is based primarily on a few case studies and anecdotal evidence, but a formal analysis of global temporal trends in jellyfish populations has been missing. Here, we analyze all available long-term datasets on changes in jell...

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 measurements the samples were taken for laboratory determination of phytopla...

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 facto...

The shallow and land-locked northern Adriatic basin has undergone several changes at different trophic levels over the last decades, of which the most recent and basin-wide is the negative trend in concentrations of chlorophyll a over the last decade. To investigate it in detail, we performed a robust analysis of abiotic parameters and plankton com...

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 meso-zooplankton were assessed. At most stations we observed a thermocline...

Authors provide the state of knowledge on marine non-indigenous species in waters off Slovenia. According to published records and authors unpublished data at least 15 non-indigenous species were up to date recorded in the Slovenian part of the Adriatic sea. Eleven species were considered as established and four species as casual. The vectors of in...

Mass occurrences of scypozoan medusae have become increasingly common in recent decades in European seas, including species in the genera Aurelia and Rhizostoma. We inferred the phylogeographic patterns of metagenetic scyphozoa Aurelia spp. and Rhizostoma pulmo from mitochondrial COI and nuclear ITS regions. No genetic structure was detected in R....

Jellyfish blooms have increased in coastal areas around the world and the outbreaks have become longer and more frequent over the past few decades. The Mediterranean Sea is among the heavily affected regions and the common bloom-forming taxa are scyphozoans Aurelia aurita s.l., Pelagia noctiluca, and Rhizostoma pulmo. Jellyfish have few natural pre...

A two - way ANOVA without replication was performed to assess difference in the bacterial abundance, protein and ammonium (NH4+) concentrations between jellyfish treatments (A, P, R) and the control (C) and to detect temporal changes for each of the parameters. (PDF)

A two - way ANOVA with replication was performed to assess difference in the bacterial carbon production among all treatments (A, P, R and C) and to detect temporal changes. (PDF)

16S rRNA gene clone libraries. Bacterial clones from T0, C9, A9, P9 and R6 16S rRNA gene clone libraries from a jellyfish - enrichment experiment in 2009 in the Gulf of Trieste with their accession numbers. In the table there is also the name and an accession number of their closest relative in GeneBank (NCBI) with % of similarity, family, taxon an...