Special Issue "Patterns and Ecology of Jellyfish in Marine Environment"

A special issue of Diversity (ISSN 1424-2818). This special issue belongs to the section "Marine Diversity".

Deadline for manuscript submissions: closed (30 April 2021).

Special Issue Editors

Prof. Dr. Alenka Malej
E-Mail
Guest Editor
Marine Biology Station Piran, National Institute of Biology, Slovenia
Interests: marine biology; plankton ecology; eutrophication; jellyfish
Dr. Agustín Schiariti
E-Mail Website
Guest Editor
Instituto Nacional de Investigacion y Desarrollo Pesquero, Mar de Plata, Argentina
Interests: ecology and life history traits of gelatinous zooplankton; jellyfish fisheries

Special Issue Information

Dear Colleagues,

It is our pleasure and privilege to invite you to contribute to this Special Issue of the Diversity journal on "Patterns and Ecology of Jellyfish in Marine Environment". Gelatinous taxa within the Cnidaria, Ctenophora, and pelagic Chordata are ubiquitous members of plankton communities, and many taxa within these groups can rapidly increase their population size and form large blooms. These organisms play essential roles as consumers and hosts in diverse symbiotic relationships, and are important prey of some charismatic species such as marine turtles. Human interactions with jellyfish are various as anthropogenic activities may promote blooms and their harmful effects on social wellbeing. Conversely, recent research points to the beneficial ecosystem services provided by jellyfish.

The purpose of this Special Issue is to enhance our knowledge across the full spectrum of disciplinary and interdisciplinary jellyfish research. We welcome research contributions in the form of original and review papers, methodological papers, perspective articles with a personal point of view on the state of the art of jellyfish research, short notes, and contributions that may include short, narrated scientific videos.

Prof. Dr. Alenka Malej
Dr. Agustín Schiariti
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All papers will be peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Diversity is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 1800 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • gelatinous zooplankton
  • cnidarians
  • ctenophores
  • pelagic tunicates
  • ecology
  • ecosystem functioning
  • anthropogenic pressures
  • ecosystem services

Published Papers (13 papers)

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Research

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Article
Respiration Rates, Metabolic Demands and Feeding of Ephyrae and Young Medusae of the Rhizostome Rhopilema nomadica
Diversity 2021, 13(7), 320; https://doi.org/10.3390/d13070320 - 14 Jul 2021
Viewed by 428
Abstract
Jellyfish (cnidarians and ctenophores) affect the marine food web through high feeding rates and feeding efficiency, but in contrast to their great importance in the ecosystem, our knowledge of their dietary requirements is limited. Here we present the results of respiratory and feeding [...] Read more.
Jellyfish (cnidarians and ctenophores) affect the marine food web through high feeding rates and feeding efficiency, but in contrast to their great importance in the ecosystem, our knowledge of their dietary requirements is limited. Here we present the results of respiratory and feeding trials of the rhizostome Rhopilema nomadica, the dominant scyphozoan in the waters of the Eastern Mediterranean, which often establishes massive swarms, mainly in the summer months. Through multiple measurements of oxygen demand in R. nomadica at bell diameters of 3–49 mm, we were able to assess its minimum energetic requirements. These, and the results of the feeding trials on individuals of the same bell diameter range, show that R. nomadica is a very efficient predator. When presented with prey concentrations of 100 prey items per liter, a single hourly feeding session provided between 1.15 and 3 times the estimated daily basal carbon requirement. Our findings suggest that R. nomadica is well adapted to its environment, the hyperoligotrophic waters of the eastern Mediterranean, able to efficiently exploit patches of plankton, possibly at rates even higher than what we observed under laboratory conditions. Full article
(This article belongs to the Special Issue Patterns and Ecology of Jellyfish in Marine Environment)
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Article
Unfolding Jellyfish Bloom Dynamics along the Mediterranean Basin by Transnational Citizen Science Initiatives
Diversity 2021, 13(6), 274; https://doi.org/10.3390/d13060274 - 17 Jun 2021
Cited by 1 | Viewed by 508
Abstract
Science is addressing global societal challenges, and due to limitations in research financing, scientists are turning to the public at large to jointly tackle specific environmental issues. Citizens are therefore increasingly involved in monitoring programs, appointed as citizen scientists with potential to delivering [...] Read more.
Science is addressing global societal challenges, and due to limitations in research financing, scientists are turning to the public at large to jointly tackle specific environmental issues. Citizens are therefore increasingly involved in monitoring programs, appointed as citizen scientists with potential to delivering key data at near to no cost to address environmental challenges, therein fostering scientific knowledge and advising policy- and decision-makers. One of the first and most successful examples of marine citizen science in the Mediterranean is represented by the integrative and collaborative implementation of several jellyfish-spotting campaigns in Italy, Spain, Malta, and Tunisia starting in 2009. Altogether, in terms of time coverage, geographic extent, and number of citizen records, these represent the most effective marine citizen science campaigns thus far implemented in the Mediterranean Sea. Here, we analyzed a collective database merging records over the above four countries, featuring more than 100,000 records containing almost 25,000 observations of jellyfish specimens collected over a period of 3 to 7 years (from 2009 to 2015) by citizen scientists participating in any of the national citizen science programs included in this analysis. Such a wide citizen science exercise demonstrates a valuable and cost-effective tool to understanding ecological drivers of jellyfish proliferation over the Western and Central Mediterranean basins, as well as a powerful contribution to developing tailored adaptation and management strategies; mitigating jellyfish impacts on human activities in coastal zones; and supporting implementation of marine spatial planning, Blue Growth, and conservation strategies. Full article
(This article belongs to the Special Issue Patterns and Ecology of Jellyfish in Marine Environment)
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Article
Observations on the Surface Structure of Aurelia solida (Scyphozoa) Polyps and Medusae
Diversity 2021, 13(6), 244; https://doi.org/10.3390/d13060244 - 31 May 2021
Viewed by 469
Abstract
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 [...] Read more.
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 and discharged. Cilia were also the most prominent features on the surface of adult medusa, protruding from the epidermal cells and with microvilli surrounding the base. Histochemical methods and various microscopy techniques (light/epifluorescence and electron microscopy) confirmed the presence of abundant mucus around polyps and on the surfaces of adult medusa, and that the mucus contained acidic and neutral mucins. The observed mucus secretions on the exumbrella surface of the medusae were in the form of granules, flocs, and sheets. Scanning electron microscopy and transmission electron microscopy analyses confirmed the presence of various microbes in the mucus samples, but not on the epithelial surfaces of the polyps or the exumbrella of the medusae. Full article
(This article belongs to the Special Issue Patterns and Ecology of Jellyfish in Marine Environment)
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Communication
The Young Stages of the Cannonball Jellyfish (Stomolophus sp. 2) from the Central Gulf of California (Mexico)
Diversity 2021, 13(6), 229; https://doi.org/10.3390/d13060229 - 24 May 2021
Viewed by 687
Abstract
Exploitation of the cannonball jellyfish (Stomolophus sp. 2) is increasing in Mexico and USA due to successful fisheries associated with seasonal blooms in coastal areas. Previously, it was proposed that such blooms could be identified by recognizing the presence of young stages [...] Read more.
Exploitation of the cannonball jellyfish (Stomolophus sp. 2) is increasing in Mexico and USA due to successful fisheries associated with seasonal blooms in coastal areas. Previously, it was proposed that such blooms could be identified by recognizing the presence of young stages in the water. In our work, we aim to describe the young stages (ephyra and metaephyra) found in the Las Guásimas lagoon, Sonora, Mexico. The description of specimens is based on photographs, drawings, and morphological measurements aimed at helping in the early detection of blooming events. Full article
(This article belongs to the Special Issue Patterns and Ecology of Jellyfish in Marine Environment)
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Article
Citizens’ Eyes on Mnemiopsis: How to Multiply Sightings with a Click!
Diversity 2021, 13(6), 224; https://doi.org/10.3390/d13060224 - 22 May 2021
Viewed by 512
Abstract
Monitoring the spreading of marine invasive species represents one of the most relevant challenges for marine scientists in order to understand their impact on the environment. In recent years, citizen science is becoming more and more involved in research programs, especially taking advantage [...] Read more.
Monitoring the spreading of marine invasive species represents one of the most relevant challenges for marine scientists in order to understand their impact on the environment. In recent years, citizen science is becoming more and more involved in research programs, especially taking advantage of new digital technologies. Here, we present the results obtained in the first 20 months (from 12 July 2019 to 8 March 2021) since launching avvistAPP. This new app was conceived to track the spreading of the invasive ctenophore Mnemiopsis leidyi in the Adriatic Sea; it was also designed to collect sightings of 18 additional marine taxa (ctenophores, jellyfish, sea turtles, dolphins, salps and noble pen shell). A total of 1224 sightings were recorded, of which 530 referred to Mnemiopsis, followed by the scyphozoan jellyfish Rhizostoma pulmo (22%), Cotylorhiza tuberculata (11%) and Aurelia spp. (8%). avvistAPP produced data confirming the presence of Mnemiopsis (often in abundances > 20 individuals m−2) along almost the entire Italian coast in the summer of 2019 and 2020. Full article
(This article belongs to the Special Issue Patterns and Ecology of Jellyfish in Marine Environment)
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Article
Contrasting Effects of Regional and Local Climate on the Interannual Variability and Phenology of the Scyphozoan, Aurelia coerulea and Nemopilema nomurai in the Korean Peninsula
Diversity 2021, 13(5), 214; https://doi.org/10.3390/d13050214 - 17 May 2021
Viewed by 509
Abstract
The East Asian marginal seas are among the most productive fisheries grounds. However, in recent decades they experienced massive proliferations of jellyfish that pose vast challenges for the management of harvested fish stocks. In the Korean Peninsula, the common bloom-formers Scyphozoan species Aurelia [...] Read more.
The East Asian marginal seas are among the most productive fisheries grounds. However, in recent decades they experienced massive proliferations of jellyfish that pose vast challenges for the management of harvested fish stocks. In the Korean Peninsula, the common bloom-formers Scyphozoan species Aurelia coerulea and Nemopilema nomurai are of major concern due to their detrimental effects on coastal socio-ecological systems. Here, we used pluriannual field observations spanning over 14 years to test the extent of climate influence on the interannual variability and bloom dynamics of A. coerulea and N. nomurai. To depict climate-jellyfish interactions we assessed partitioning effects, direct/indirect links, and the relative importance of hydroclimate forces on the variability of these species. We show that jellyfish interannual patterns and bloom dynamics are shaped by forces playing out at disparate scales. While abundance changes and earlier blooms of A. coerulea were driven by local environmental conditions, N. nomurai interannual patterns and bloom dynamics were linked with regional climate processes. Our results provide a synoptic picture of cascading effects from large scale climate to jellyfish dynamics in the Korean Peninsula that may affect fisheries sustainability due to the prominent detrimental impact these species have in the region. Full article
(This article belongs to the Special Issue Patterns and Ecology of Jellyfish in Marine Environment)
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Article
Scyphomedusae and Ctenophora of the Eastern Adriatic: Historical Overview and New Data
Diversity 2021, 13(5), 186; https://doi.org/10.3390/d13050186 - 28 Apr 2021
Cited by 2 | Viewed by 790
Abstract
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 [...] Read more.
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 phenological data and relative abundances of jellyfish based on 2010–2019 scientific surveys and a “citizen science” sighting program along the eastern Adriatic. Inter-annual variability, seasonality and spatial distribution patterns of Scyphomedusae and Ctenophore species were described and compared with existing historical literature. Mass occurrences with a clear seasonal pattern and related to the geographical location were observed for meroplanktonic Scyphomedusae Aurelia solida, Rhizostoma pulmo, and to a lesser extent Chrysaora hysoscella, Cotylorhiza tuberculata and Discomedusa lobata. Holoplanktonic Pelagia noctiluca also formed large aggregations, which were seasonally less predictable and restricted to the central and southern Adriatic. Four species of Ctenophora produced blooms limited to a few areas: Bolinopsis vitrea, Leucothea multicornis, Cestum veneris and the non-native Mnemiopsis leidyi. However, differences between Adriatic subregions have become less pronounced since 2014. Our results suggest that gelatinous organisms are assuming an increasingly important role in the Adriatic ecosystem, which may alter the balance of the food web and lead to harmful and undesirable effects. Full article
(This article belongs to the Special Issue Patterns and Ecology of Jellyfish in Marine Environment)
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Article
Dissolved Oxygen-And Temperature-Dependent Simulation of the Population Dynamics of Moon Jellyfish (Aurelia coerulea) Polyps
Diversity 2021, 13(5), 184; https://doi.org/10.3390/d13050184 - 28 Apr 2021
Viewed by 419
Abstract
As the extent of hypoxia in coastal waters increases, the survivorship of jellyfish polyps relative to that of competing sessile organisms often increases, enabling them to reproduce more prolifically, leading to a medusa bloom in the following year. Quantifying the population of polyps [...] Read more.
As the extent of hypoxia in coastal waters increases, the survivorship of jellyfish polyps relative to that of competing sessile organisms often increases, enabling them to reproduce more prolifically, leading to a medusa bloom in the following year. Quantifying the population of polyps can be used to predict when these blooms will occur. We used a time-delayed logistic equation to quantify the response to variable dissolved oxygen (DO) concentrations and temperatures in a population of moon jellyfish (Aurelia coerulea) polyps on substrates that carried competing sessile organisms. The availability of substrate depends on the DO threshold for each competitor, and substrates only become available to the polyps during hypoxic periods. We used the median sublethal concentration (SLC50) thresholds of hypoxia for different groups of benthic organisms to calculate the DO-dependent survivorship of A. coerulea polyps competing on the substrate. Since the median lethal time (LT50) for cnidarians is close to 240 h, we chose a 10-day delay in the time-delayed logistic equation. The carrying capacity is determined every 10 days depending on DO concentrations and temperature. The polyps reproduce by budding at a temperature-dependent rate after settling on the substrate during the hypoxic period, and thus, the annual polyp reproduction rate is determined by multiplying the temperature-dependent budding rate by the DO-dependent survivorship. The duration of hypoxia is a key factor determining the polyp population, which can increase more as the duration of hypoxia increases. Modeling simulations were compared to observed data. In this model, the DO and temperature distribution data make it possible to quantify variations in the population of the A. coerulea polyps, which can be used to predict the abundance and appearance of medusa the following year. Full article
(This article belongs to the Special Issue Patterns and Ecology of Jellyfish in Marine Environment)
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Article
Asexual Reproduction and Strobilation of Sanderia malayensis (Scyphozoa, Pelagiidae) in Relation to Temperature: Experimental Evidence and Implications
Diversity 2021, 13(2), 37; https://doi.org/10.3390/d13020037 - 21 Jan 2021
Cited by 1 | Viewed by 719
Abstract
Sanderia malayensis is a scyphozoan species present in the Indian and Pacific Oceans, ranging from the Suez Canal to Japan. Although this jellyfish is commonly kept in aquariums around the world, there is a knowledge gap regarding its biology and ecology, especially at [...] Read more.
Sanderia malayensis is a scyphozoan species present in the Indian and Pacific Oceans, ranging from the Suez Canal to Japan. Although this jellyfish is commonly kept in aquariums around the world, there is a knowledge gap regarding its biology and ecology, especially at the polyp stage. In this study, we tested the asexual reproductive activity of S. malayensis at three different temperatures: 10, 15 and 20 °C. Results showed significant increases of polyps at 15 and 20 °C, and a minimum at 10 °C, corresponding with daily budding rates of 6.61% ± 0.92%, 5.85% ± 2.36% and 0.66% ± 0.24%, respectively. Moreover, a second experiment was carried out to report about the ability of S. malayensis to prey on Aurelia solida at the ephyra stage. Unidirectional predation of S. malayensis ephyrae on A. solida and an absence of inverse predation was observed. These results could give new insights on the potential fitness and survival of this species if it will ever invade the Mediterranean Sea. Full article
(This article belongs to the Special Issue Patterns and Ecology of Jellyfish in Marine Environment)
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Review

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Review
Population Structures and Levels of Connectivity for Scyphozoan and Cubozoan Jellyfish
Diversity 2021, 13(4), 174; https://doi.org/10.3390/d13040174 - 19 Apr 2021
Viewed by 628
Abstract
Understanding the hierarchy of populations from the scale of metapopulations to mesopopulations and member local populations is fundamental to understanding the population dynamics of any species. Jellyfish by definition are planktonic and it would be assumed that connectivity would be high among local [...] Read more.
Understanding the hierarchy of populations from the scale of metapopulations to mesopopulations and member local populations is fundamental to understanding the population dynamics of any species. Jellyfish by definition are planktonic and it would be assumed that connectivity would be high among local populations, and that populations would minimally vary in both ecological and genetic clade-level differences over broad spatial scales (i.e., hundreds to thousands of km). Although data exists on the connectivity of scyphozoan jellyfish, there are few data on cubozoans. Cubozoans are capable swimmers and have more complex and sophisticated visual abilities than scyphozoans. We predict, therefore, that cubozoans have the potential to have finer spatial scale differences in population structure than their relatives, the scyphozoans. Here we review the data available on the population structures of scyphozoans and what is known about cubozoans. The evidence from realized connectivity and estimates of potential connectivity for scyphozoans indicates the following. Some jellyfish taxa have a large metapopulation and very large stocks (>1000 s of km), while others have clade-level differences on the scale of tens of km. Data on distributions, genetics of medusa and polyps, statolith shape, elemental chemistry of statoliths and biophysical modelling of connectivity suggest that some of the ~50 species of cubozoans have populations of surprisingly small spatial scales and low levels of connectivity. Despite their classification as plankton, therefore, some scyphozoans and cubozoans have stocks of small spatial scales. Causal factors that influence the population structure in many taxa include the distribution of polyps, behavior of medusa, local geomorphology and hydrodynamics. Finally, the resolution of patterns of connectivity and population structures will be greatest when multiple methods are used. Full article
(This article belongs to the Special Issue Patterns and Ecology of Jellyfish in Marine Environment)
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Review
Diversity and Physiological Tolerance of Native and Invasive Jellyfish/Ctenophores along the Extreme Salinity Gradient of the Baltic Sea
Diversity 2021, 13(2), 57; https://doi.org/10.3390/d13020057 - 02 Feb 2021
Viewed by 1302
Abstract
Global change has led to manifold changes of marine ecosystems and biodiversity world-wide. While it has been shown that certain jellyfish and comb jelly species have increased regionally, it remains to be investigated if this is a general trend or localized phenomenon. Especially [...] Read more.
Global change has led to manifold changes of marine ecosystems and biodiversity world-wide. While it has been shown that certain jellyfish and comb jelly species have increased regionally, it remains to be investigated if this is a general trend or localized phenomenon. Especially for the economically important Baltic Sea, which is characterized by an extreme physical environmental gradient, this question has not been addressed to date. Here we present a detailed account of the gelatinous macro-zooplankton community including their physiological tolerance towards abiotic conditions and resulting distribution ranges in the Baltic. We show that the arrival and establishment of non-indigenous species has led to a rising importance of jellyfish and comb jellies in the Baltic. This accounts for the comb jelly Mnemiopsis leidyi, which was first observed in Northern Europe in 2005, as well as for the hydromedusae Blackfordia virginica, first sighted in 2014. Both species have been shown to attain high population densities with pronounced grazing impact in other invasive regions. Given the current and anticipated changes of the physical environment of the Baltic Sea, especially ongoing warming, amplification of their impact can be expected. Full article
(This article belongs to the Special Issue Patterns and Ecology of Jellyfish in Marine Environment)
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Other

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Interesting Images
Why Do Only Males of Mawia benovici (Pelagiidae: Semaeostomeae: Scyphozoa) Seem to Inhabit the Northern Adriatic Sea?
Diversity 2021, 13(6), 222; https://doi.org/10.3390/d13060222 - 21 May 2021
Viewed by 631
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 [...] Read more.
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. Full article
(This article belongs to the Special Issue Patterns and Ecology of Jellyfish in Marine Environment)
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Observations on the Feeding of Drymonema dalmatinum in the Gulf of Trieste
Diversity 2021, 13(4), 163; https://doi.org/10.3390/d13040163 - 08 Apr 2021
Cited by 1 | Viewed by 1199
Abstract
The largest scyphozoan jellyfish of the Mediterranean Sea, Drymonema dalmatinum was first described by Haeckel [...] Full article
(This article belongs to the Special Issue Patterns and Ecology of Jellyfish in Marine Environment)
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