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Detection of an unusual presence of the cubozoan Carybdea marsupialis at shallow beaches located near Denia, Spain (south-western Mediterranean)
Abstract
An unusual bloom of the cubozoan Carybdea marsupialis occurred at some beaches located near Denia (south-western Mediterranean Sea, south-eastern Spain) during the summer of 2008. The bloom was first detected and recorded by the local Red Cross first aid services. Densities of C. marsupialis in the area were characterized by quantitative sampling. The number of bathers stung totalled 3330 during the three months of summer. Sampling at shallow beaches from 15 September to 21 November 2008 gave insights into cubozoan density in the area, estimated at 265.9 individuals per 100 m2 as the highest value. These densities have never been recorded previously in the Mediterranean where the species was considered to be rare. Mean density along the 17 km of coastline which was sampled reached 5.4 + 3.8 ind/100 m2. Data on size distribution are also given. This paper analyses the reasons behind these unusually high abundances of C. marsupialis in the north-western Mediterranean Sea and provides guidelines for future studies to elucidate the causes of this bloom.
... These gaps are a result of the challenges associated with detecting and subsequently studying these animals in their natural environment, resulting from their spatial and temporal variability, transparency, cryptic nature, and the fact that they commonly reside in waters of low visibility (Kingsford and Mooney, 2014). Multiple techniques have been utilised to detect jellyfish, including in-situ visual observations (Brown, 1973, Pitt and, various styles/sizes of netting , Gordon et al., 2004, Bordehore et al., 2011, light attraction techniques (Barnes, 1966, Llewellyn et al., 2016, acoustics (Zhang et al., 2019, Lee et al., 2007, and most recently drones (Rowley et al., 2020, Schaub et al., 2018, Rowe et al., 2022. Each method has benefits and limitations, depending on the application and ambient conditions. ...
... Research focus has largely been placed upon detecting the medusae stage of cubozoan jellyfish due to their direct threat to human health and enterprise (Fenner et al., 1996, Fenner and Harrison, 2000, Gershwin et al., 2013, Bordehore et al., 2011. However, cubozoans have a polymorphic life history consisting of two major stages, the medusae and polyp stages Mooney, 2014). ...
... The research within this thesis builds on these findings by directly assessing the Given the spatio-temporal abundance and distribution data available for some cubozoan species , Bordehore et al., 2011, Rowley et al., 2022, Bordehore et al., 2023, it is plausible that similar patterns of localised population structures may exist for other cubozoan taxa. There will, however, be exceptions to this. reported populations of Alatina alata across the Pacific to not be genetically distinct, therefore being highly connected. ...
Cubozoans, commonly referred to as box jellyfish, are a class of marine taxa which contain members described as the most venomous organisms on the planet. They are found in warm tropical waters around the globe and have multiple unique attributes which have garnered them significant research interest. These attributes include their visual capabilities, life histories, swimming abilities, and, most notably, their potent venom. Stings from dangerous members can result in severe reactions, hospitalisation, and potentially death. The ability to manage this risk of envenomation is a challenge faced by stakeholders and decision makers globally. Despite this, cubozoan jellyfish are largely understudied and ecological data on the majority of species are limited. To overcome the threats and challenges which these taxa pose, an increased understanding of their ecology is needed. Significant knowledge gaps exist surrounding cubozoan jellyfish life histories and population structures. These gaps stem from the challenges associated with their detection, a result of their elusive nature, transparency, and spatial and temporal variability in abundance. Moreover, these gaps persist due to limitations of current detection and sampling techniques in addressing the logistical difficulties of studying these aspects of cubozoan ecology.
The broad objective of this thesis was to explore the use of eDNA as an innovative technique for detecting and studying deadly cubozoan jellyfish. The development of a robust assay (Chapter 2) was a prerequisite for the application of the technique for studying the ecology of medusae and polyps in open and closed marine environments (Chapters 3 & 4). Finally, estimates of spatiotemporal detection limits were determined by modelling the dispersal of eDNA (Chapter 5).
The development and optimisation of an eDNA assay for Chironex fleckeri revealed the technique’s high utility for the detection of the potentially deadly jellyfish (Chapter 2). The assay was designed to target a region of the mitochondrial 16S rRNA gene which contained both interspecific and intraspecific variability. This allowed for the assay to be highly specific, ensuring it could distinguish C. fleckeri from closely related species, while ensuring its ability to detect the species across its biogeographic distribution. Field trials demonstrated this, with C. fleckeri medusae being detected at locations across the species range, where they were known and confirmed to be present. Multiplexing the assay with an endogenous control allowed for enhanced quality control, ensuring reliability in all stages of the technique’s workflow. This, additionally, enabled reliability and confidence in field detections, limiting the potential for false positive or false negative detections. Additionally, the assay was found to be highly sensitive, with an effective limit of detection of 0.45 copies/reaction when utilising six technical replicates. This sensitivity provided assurance of a powerful and reliable detection tool, especially due to the high spatial and temporal variability in C. fleckeri abundance. Mesocosm experimentation revealed a rapid decay rate of C. fleckeri eDNA (99% within 27 hours), with no detectable variation in this rate across minor temperature changes. This provided essential insights into the temporal resolution of the technique, and with knowledge on the movements and behaviours of C. fleckeri, suggested that detections likely reflected the species’ close proximity. These findings demonstrate that eDNA offers a highly effective and precise tool for detecting C. fleckeri, hence addressing a key challenge in determining the species’ presence.
The application of eDNA in Port Musgrave provided critical evidence that C. fleckeri have spatially small stock populations. The relatively enclosed estuarine system served as a habitat for both medusae and polyps (Chapter 3). eDNA samples were collected across various habitats, including sandy beaches and mangroves, during the jellyfish season, and outside of the season when only polyps would be present. Accordingly, eDNA proved to be an effective tool to locate the elusive benthic polyp stage of C. fleckeri, which are the source of the free-swimming medusae stage. Polyps were detected exclusively within the Port, specifically around rocky substrata along sandy beaches, with no detections in mangrove habitat. This suggested that polyps exhibit distinct habitat preferences, similar to those observed in other cnidarian species, particularly scyphozoan jellyfish. Medusae were detected at a high frequency inside, and more sporadically outside, of the estuarine system, suggesting that the species moves between these areas, aligning with known patterns of the jellyfish’s movement. The distinct spatial distributions of medusae and polyps enabled an evaluation of their population boundaries, suggesting that the Port likely contains a population stock of the species. This finding supports growing evidence of spatially restricted population stocks of some cubozoan jellyfish. Finally, while eDNA proved highly effective for C. fleckeri detection, its use as a proxy for abundance was limited, likely due to the high variability in eDNA shed by the low abundance and spatially dispersed species.
In Chapter 4, the eDNA data collected in the open coastal environment of Magnetic Island built on the findings from Port Musgrave, providing further insights into the spatial distribution and source locations of C. fleckeri. The study area, encompassing Horseshoe and Maud Bays, featured oceanographic and geomorphic conditions expected to facilitate greater dispersal of the jellyfish, when compared to the semi- enclosed estuarine system of Chapter 3. Environmental DNA samples were collected across nearshore, mid-shore and offshore locations both during the jellyfish season and non-seasonal months. Medusae were detected exclusively in nearshore areas, consistent with their known distribution, confirming the ability of eDNA to accurately capture the spatial presence of the species. Outside of the jellyfish season, polyps were detected near freshwater inflows, with the highest frequency of detections occurring in Horseshoe Bay. This supported the hypothesis, based upon empirical medusae size- distribution data, that Horseshoe Bay serves as a source location for C. fleckeri on the island. Polyps were detected in habitats with rocky substrata, consistent with previous findings. A comparison of the distributions of both life history stages, where medusae were exclusively detected nearshore and polyps consistently detected in Horseshoe Bay, suggested that the northern side of Magnetic Island likely represents a population stock of the jellyfish. Sampling in both semi-enclosed and open environments added further evidence to a developing paradigm of spatially restricted C. fleckeri stocks.
Finally, in Chapter 5, focus shifted to understanding the spatiotemporal dispersion and detectability of C. fleckeri eDNA through the utilisation of biophysical models, to better understand the relationship between eDNA detections and the physical presence of the jellyfish. The spatiotemporal detectability of eDNA was found to be spatially restricted, across 100s of meters to kilometres, despite potential for particles to travel distances of up to 10s of kilometres. This was, as expected, primarily influenced by both particle dilution and decay. Local hydrodynamics, including tidal flows and wind- driven surface currents, played a key role in shaping dispersal patterns, leading to heterogeneous movements and retention of eDNA across small spatial scales. Estimated spatiotemporal detection limits aligned with the results of empirical detections (Chapter 4).
In summary, this thesis has demonstrated the effectiveness of eDNA as a powerful ecological sampling tool for detecting and studying cubozoan jellyfish across their key life history stages. The development of a highly specific and sensitive eDNA assay enabled accurate detection of both medusae and polyp life history stages, and provided critical insights into their spatial distribution, habitat preferences, and population structures. Specifically, the efficient detection of polyps is a crucial advancement, offering a new approach to detect and study this life history stage. This knowledge on polyps is vital for effective management strategies as they are the source of stinging medusae. The findings of this thesis additionally add to growing evidence of some cubozoan species, including C. fleckeri, maintaining spatially small population stocks, to the scale of bays and estuaries, with these findings being ecologically robust across differing environmental settings. The ubiquitous nature of DNA makes this genetic detection tool applicable for all ~50 cubozoan species, highlighting its potential to further ecological understanding on other problematic cubozoans, such as the notorious ‘Irukandji’ jellyfish, Carukia barnesi. Additionally, eDNA shows considerable promise as a potential management tool, offering an efficient method for early detection and potential mitigation of the risks posed by these taxa. While eDNA proved highly effective in detecting presence, limitations as a proxy for abundance, its inability to determine size/age distributions, and behavioural patterns were acknowledged, emphasising the need for a multifaceted approach for the comprehensive study of cubozoan ecology. As molecular genetic techniques advance, future research efforts may refine cubozoan detections by offering finer temporal and spatial resolution, potentially enabling targeted collection and in-situ study of these jellyfish. Collectively, the findings of this thesis contribute significantly to the field of cubozoan jellyfish ecology and showcase the high applicability of eDNA as an ecological sampling tool to detect and study these taxa.
... It has also been observed sporadically in mass aggregations in the Adriatic Sea [5,6,7] as well as has been recorded in Portuguese waters [8]. Massive numbers of the box jellyfish C. marsupialis were already recorded at some beaches at Denia (Alicante, Spain) in 2008 [9]. Local scientists expressed significant concern about the massive increase in box jellyfish populations on beaches, as this could jeopardize the health of swimmers and divers owing to their neurotoxic and hemolytic properties, which adversely affect red blood cells. ...
... It mainly favors ports, marina environments and also sandy beaches. [9] located this medusa species in Denia (East Spain) at depths between 0.5 and 1.2m, whilst [3] observe did at 1.3-2 depth on the coast of Tunisia. This box jellyfish complex eyes that provide advanced visual capabilities. ...
... C. marsupialis is an oviparous, gonochoric species with a two-phase life cycle: 1-Benthic polyp: attached to the substrate and reproducing asexually. 2-Pelagic jellyfish: free-swimming and reproducing sexually [9,10]. C. marsupialis holds an important role in marine food chains in specific localized areas, acting as a top-down predator of zooplankton and ichthyoplankton [11,12]. ...
This research investigates the presence and ecological dynamics of Carybdea marsupialis along the Moroccan Mediterranean and North Atlantic coasts from 2017 to 2023. An analysis of 101 specimens revealed significant seasonal and spatial variability linked to environmental parameters. Observations underscored the species' impact on local ecosystems and potential risks to human activities. These findings emphasize the necessity for continuous monitoring and further research to understand the proliferation of this species and mitigate its ecological and economic impacts.
... Among the zooplankton taxonomic groups, jellyfish, here referred to as Hydrozoa (species with exclusive benthic stage excluded), Scyphozoa, Cubozoa and Ctenophora, have led during the last decade a rise of interest in the Mediterranean Sea due to the various impacts of their mass proliferation, such high bathers stung records (Bordehore et al., 2011) (e.g. 45 000 people stung in summer 2004 in Monaco (Purcell et al., 2007)), tourism economic (Ghermandi et al., 2015) and fisheries losses (Bosch-Belmar et al., 2021). However, this interest increase is not only driven by their potential negative impacts but also by their ecology. ...
... In Tunisia, the species has been observed only in the TP, specifically in Hammamet (Gueroun et al., 2015a) in 2014 and later in Sousse (Fig. 5). C. marsupialis distribution is usually associated with shallow (0.5-10 m) coastal sandy beaches, with a gentle slope where Posidonia oceanica meadows and Caulerpa prolifera coexist with rocky and sandy bottoms (Bordehore et al., 2011;Acevedo et al., 2013;Gueroun et al., 2015a). This spatial distribution associated with the summer occurrence of the species constitutes a genuine socioeconomic concern. ...
... This spatial distribution associated with the summer occurrence of the species constitutes a genuine socioeconomic concern. In Spain, jellyfish stinging incidences increased dramatically in 2008, coinciding with the C. marsupialis outbreak (Bordehore et al., 2011). C. marsupialis sting causes severe pain, a burning sensation, erythematous-vesicular eruption, local oedema and systemic effects (Peca et al., 1997;Bordehore et al., 2015). ...
Jellyfish (Cnidaria and Ctenophora) are an essential component of the marine ecosystems and represent a potential source, positive or negative, for several economic’ activities. Jellyfish outbreaks and Non-Indigenous Species (NIS) introduction can shift the ecological community structure and energy transfer. Despite their importance in the ecosystem’s function and services, jellyfish fauna diversity and phenology knowledge are uneven, the southern Mediterranean Sea being poorly investigated. Here, we present an overview of the current state of jellyfish biodiversity in Tunisia. Based on a comprehensive literature survey, historical records, and unpublished data, 66 jellyfish species, including 11 Non-Indigenous Species, have been recorded in Tunisia between 1994 and 2020. Additionally, based on field surveys and a citizen science sighting program between 2004 and 2020, we present the spatial distribution of 13 conspicuous jellyfish taxa and the phenology of the eight most frequently detected species (Aurelia solida, Cotylorhiza tuberculata, Pelagia noctiluca, Phyllorhiza punctata, Rhizostoma pulmo, Rhopilema nomadica, Olindias muelleri and Velella velella) in Tunisian two ecoregions, Western Mediterranean and Tunisian Plateau. The 17 years surveys showed a shift in R. pulmo, A. solida and P. noctiluca phenology. Additionally, citizen science revealed P. punctata (NIS) spatial spreading and the distinct phenology between the two ecoregions populations.
... The species C. marsupialis prefers warm and temperate waters and is frequently found close to the coasts. It has been reported in massive numbers in Tunisia, Spain and the Italian coasts in the Adriatic Sea (Bordehore et al. 2011;Boero 2013;Gueroun et al. 2015). No reports exist for the Ionian side of the Basilicata region in the Global Biodiversity Information Facility dataset or in some bibliographic works (GBIF 2024). ...
... In addition, the species seem to be favored by the high ratio of anthropogenic nutrients and human activities such as coastal constructions (Acevedo 2016). In fact, a high number of sightings of the species come from areas close to ports and marinas, which indicates that coastal constructions can be suitable settlement substrates for the planulae of the species (Bordehore et al. 2011;Boero 2013;Gueroun et al. 2015;Zammit et al. 2015). The increasing presence of C. marsupialis in the Mediterranean raises questions about the future of marine ecosystems and the impact of climate change. ...
The study documents the presence of the box jellyfish Carybdea marsupialis in the waters of the Ionian Sea in Italy, which constitutes important data for the knowledge of new areal distribution of this species along the coasts of the Mediterranean basin. Carybdea marsupialis belongs to the phylum Cnidaria, class Cubozoa, and is known for its stinging and potentially dangerous stings for humans, making it a species of significant ecological and health interest. The species has previously been observed in other areas of the western Mediterranean, but the report in the Ionian Sea represents an eastward expansion of its distribution range. Results suggest that climate change, influenced by global warming processes and anthropogenic activities, facilitated the expansion of this species into the rest of the Mediterranean Sea. The work highlights the importance of continuous monitoring of indigenous and non-indigenous species and calls for international cooperation to manage any ecological impacts linked to the spread of these marine species.
... The application of dynamic modelling to cubozoans has yet to be extensively explored, although it has been the subject of study in other classes of the phylum Cnidaria. Beyond the study of these species in relation to their stings to bathers, when modelling is carried out in relation to jellyfish, it is mainly focused on understanding the dynamics of specific phenomena such as blooms (Bordehore et al., 2011), where changes in environmental variables are crucial (Li and Liu, 2022;Milisenda et al., 2018), their abundance and temporal patterns (Nocera et al., 2023) or their impact on the community of planktonic organisms (Strniša et al., 2024). Although we are not aware of any models that explore these dynamics in cubozoans, this research could be an interesting starting point for modelling jellyfish and other planktonic organisms, allowing a better understanding of certain phenomena and their dynamics, and furthermore, to simulate hypothetical scenarios representing natural phenomena and actions of anthropogenic origin, in order to decode their causes and predict their consequences. ...
Matrix models are widely used in population ecology studies and are valuable for analysing population dynamics, although they are limited in the use of time-varying parameters. This limitation can be overcome by dynamic models. In this study, we revisit a previously published study on a matrix model of a population of the box jellyfish Carybdea marsupialis (L. 1758) in the Western Mediterranean. A dynamic model integrating the transition matrix of the original model is developed in STELLA Architect with the following improvements: (1) Sensitivity study of the reliability of the methodology for calculating the transition matrix and estimation of the errors of the fitting parameters; (2) Closure of the jellyfish life cycle by adding the polyp stage. This will make it possible to simulate scenarios of ecological interest over several years such as a decline in food supply, jellyfish removal strategies, changes in drift currents and changes in substrate availability for planulae to settle. (3) The inclusion of more biological reality. In particular, a temporal pattern of strobilation is added, which improves the fit of the model to the field data.
... In the Mediterranean Sea, Carybdea marsupialis (Linnaeus, 1758) was the sole reported species of the Class Cubozoa (Acevedo et al., 2019) until the recent description of the new species Copula lucentia (Fonfría et al., 2023). Usually observed in low densities, over recent decades it has been massively detected in some Italian (Boero et al., 2016), Tunisian (Gueroun et al., 2015) and Spanish coastal zones (Bordehore et al., 2011) with abundances above 10 individuals per m À2 and maximums of 1.8 y 2.7 indiv/m À3 , respectively. Like other cubozoan jellyfish, C. marsupialis has a biphasic life cycle with a benthic polyp and a free-swimming medusa (Straehler-Pohl & Jarms, 2005). ...
Although usually considered part of the plankton, cubozoans are strong swimmers. The aim of this study was to determine the influence of the active swimming ability of the box jellyfish Carybdea marsupialis on the spatial distribution of a well‐studied population in the NW Mediterranean where adults and juveniles do not overlap geographically. To accomplish this, we analyzed the swimming speed, effective velocity, effective displacement index (EDI), and proficiency of 27 individuals with diagonal bell widths (DBWs) ranging from 1.1 to 36 mm. The laboratory analysis utilized conventional video recordings and the video analysis tool Tracker. Mean swimming speed for small juveniles, medium juveniles and adults was 9.7 ± 0.8, 21.9 ± 2.3 and 43.1 ± 1.8 mm s⁻¹ (mean ± se), respectively. Effective velocity was also proportional to size, ranging from 5.0 ± 0.7 to 38.8 ± 3.1 mm s⁻¹ (mean ± se). The calculated EDI for each group was 0.51 ± 0.05, 0.84 ± 0.06 and 0.90 ± 0.05 (mean ± se), respectively. Proficiency showed an inverse trend, from 6.4 ± 0.6 s⁻¹ for the small juveniles to 1.36 ± 0.05 for adults (mean ± se). Comparing the swimming speed results with the local currents obtained from drifting buoys analyzed in the area, adults would be able to swim strongly enough to overcome almost 70% of the currents, whereas the small juveniles would not reach 17%. This would allow larger individuals to select their habitat, while smaller individuals are left dependent on advection. Although experiments adding currents in aquaria would be necessary to confirm these theoretical results, the data obtained would be useful in improving the performance of bio‐mathematical models used to predict jellyfish blooms since, even though the sting of C. marsupialis is non‐fatal, it may produce systemic effects in sensitive swimmers.
... Research has largely focused on detecting the medusae stage of cubozoan jellyfish due to their direct threat to human health and enterprise (Fenner et al. 1996, Fenner & Harrison 2000, Bordehore et al. 2011, Gershwin et al. 2013, Bolte et al. 2021. However, cubozoans have a polymorphic life history consisting of 2 major stages, the medusa and the polyp stages (Kingsford & Mooney 2014). ...
Considerable gaps in our understanding of cubozoan ecology exist due to challenges associated with their detection. Environmental DNA (eDNA) removes the need for physical identification, offering a new approach to detect and study these elusive taxa. The objective of this study was to utilise eDNA as an ecological tool to test hypotheses surrounding the ecology of the Australian box jellyfish Chironex fleckeri , through examining the presence of both polyp and medusa life history stages. Additionally, the utility of eDNA as a proxy of abundance was explored. This study was conducted within and outside of Port Musgrave, a semi-enclosed estuarine system in northern Australia. eDNA proved successful in detecting both life history stages. Polyps were detected during winter when medusae were absent. This detection allowed investigation into potential polyp habitat. Polyps were exclusively detected in habitats characterised by nearby patches of rocky substrata and shallow carbonate reefs, with no detection occurring in mangrove habitats. The highest frequency of medusa detections occurred within Port Musgrave, while detections outside were more sporadic. Through comparing the distributions of both life history stages, evidence suggests that Port Musgrave is likely a population stock of the species, aligning with predictions from biophysical models. Finally, use of eDNA as a proxy of abundance showed a poor relationship, which can be attributed to likely higher variance in eDNA concentrations resulting from the spatially dispersed nature of the jellyfish. We conclude that eDNA provides a new approach to study cubozoan ecology and will provide critical information needed to mitigate against their threat of envenomation.
This study investigates the diversity and distribution of Medusozoa, a clade of the phylum Cnidaria, within the framework of the Iberian Peninsula and surrounding archipelagos. Medusozoa is notably recognized for encompassing jellyfish species with the capacity to exert detrimental ecological and socioeconomic impacts, this group of mostly marine organisms assumes a critical role in aquatic food webs and exhibits considerable biotechnological potential. A comprehensive dataset sourced from over 230 bibliographic references and public databases, comprising over 30,000 reports of Medusozoa in the Iberian region, reveals 593 species across the four medusozoan classes (549 hydrozoans, 37 scyphozoans, 5 staurozoans, and 2 cubozoans). Additionally, publicly available genomic, transcriptomic, and proteomic metadata from the phylum Cnidaria are incorporated. The analyses highlight Hydrozoa as the most frequently reported and diverse class in the Iberian region. Specifically, the order Leptothecata exhibits the highest diversity, while Siphonophorae stands out as the most documented with Physalia physalis emerging as the highest reported species. Spatial distribution patterns reveal that holoplanktonic species are more widespread and abundant than their benthic and meroplanktonic counterparts. Furthermore, medusozoans with a free-swimming life form display greater diversity and dispersal compared to sessile species. The Northeast Atlantic section of the region demonstrates greater medusozoan diversity compared to the Mediterranean. Key findings also include information into invasive and introduced species, bloom-forming organisms, and edible species. A sustained trend of discovering new species of Medusozoa over time was observed, underscoring untapped exploration potential in the Iberian region. The study reveals a clear limitation of omics data in cnidarians, particularly in the Medusozoa clade. This research provides an overall perspective on medusozoans in the Iberian region, underlining the importance of additional omics studies while highlighting growing interest in exploring the biotechnological potential of these organisms. This research serves as a valuable resource for future investigations, providing insights into underexplored species and those with greater ecological and socioeconomic importance.
The box jellyfish Chiropsalmus quadrumanus (Chirodropida: Cubozoa: Cnidaria) is common in warm waters. Although it is assumed that external fertilization is a characteristic of Chirodropida, the life history of C. quadrumanus is not yet known since its reproductive behavior has never been described, nor has the polyp has been found in nature. As a result, in the absence of documentation of reproductive behavior, we sought to test the hypothesis of external fertilization through a histological analysis of the female gonads. Herein, we analyze ten females collected in São Paulo and Rio de Janeiro (Brazil) and describe the gonadal organization and pattern of oocyte development. The discovery of four distinct stages of oocyte differentiation augments the scant existing reports of the structural and functional maturation of sex cells in Cubozoa species. Furthermore, the gonads of mature females comprise both mature (average diameter of 122 µm) and immature oocytes, suggesting that C. quadrumanus is iteroparous and exhibits multiple reproductive cycles during its life. Medusa bell size was not found to correlate with maturity state as even small females possessed a high percentage of oocytes in late vitellogenesis, suggesting that sexual maturation occurs rapidly in C. quadrumanus females.
Cubozoan jellyfish pose a risk of envenomation to humans and a threat to many businesses, yet crucial gaps exist in determining threats to stakeholders and understanding their ecology. Environmental DNA (eDNA) provides a cost-effective method for detection that is less labour intensive and provides a higher probability of detection. The objective of this study was to develop, optimise and trial the use of eDNA to detect the Australian box jellyfish, Chironex fleckeri. This species was the focus of this study as it is known to have the strongest venom of any cubozoan; it is responsible for more than 200 recorded deaths in the Indo-Pacific region. Further, its ecology is poorly known. Herein, a specific and sensitive probe-based assay, multiplexed with an endogenous control assay, was developed, and successfully utilised to detect the deadly jellyfish species and differentiate them from closely related taxa. A rapid eDNA decay rate of greater than 99% within 27 h was found with no detectable influence from temperature. The robustness of the technique indicates that it will be of high utility for detection and to address knowledge gaps in the ecology of C. fleckeri; further, it has broad applicability to other types of zooplankton.
The diet of cubomedusae Tamoya haplonema Müller, 1859 (Carybdeidae) and Chiropsalmus quadrumanus (Müller, 1859) (Chirodropidae) was examined in specimens collected on the Southern Brazilian coast (25º20´ - 25º55´S; 48º10´ - 48º35´W), between December 1998 and December 2004. This is the first study to analyze this biological aspect in cubomedusae from the South Atlantic. The gastrovascular cavities of most (55%; n = 29) specimens of T. haplonema were empty while the remainder had teleosteans parts such as scales, vertebrae and otoliths. In C. quadrumanus (n = 726), the most important items were the pelagic sergestid shrimp Peisos petrunkevitchi Burkenroad, 1945 and Brachyura larvae, mainly megalops. Small crabs, isopods, fish, fish eggs and nematodes were less common. A dietary shift was clearly observed during C. quadrumanus growth. Smaller individuals consumed a greater variety of prey, mostly Brachyura larvae, and they also had higher frequencies of empty stomachs. As their size increased, megalopas decreased and P. petrunkevitchi became the most important item in their diet.
Kinds and distribution of nematocysts of the cubomedusa Carybdea
marsupialis were described by light and scanning electron microscopy. Three kinds of nematocysts were found in tentacles: heterotrichous microbasic euryteles, flattened holotrichous isorhizas and subspherical holotrichous isorhizas. The microbasic euryteles of the tentacles show a characteristic detachable multilayered lancet, already described in the euryteles of Carybdea
alata. A possible explanation of the function of the lancet is proposed. The pedalia and the umbrella are armoured by holotrichous isorhizas together with an unidentified kind of small, drop-shaped nematocysts. Gastric cirri, characterized by a rough and ciliated surface, contain heterotrichous microbasic euryteles.
In spite of being one of the most relevant components of the biosphere, the plankton-benthos network is still poorly studied as such. This is partly due to the irregular occurrence of driving phenomena such as gelatinous plankton pulses in this realm. Gelatinous plankters rely on their life cycles and histories to exploit temporarily abundant resources with an undeniable, but often overlooked, impact on marine food webs. Dramatic increases of gelatinous filter-feeders and/or carnivores (both native and nonindigenous species) are frequently observed, and explanations of these blooms alternatively invoke ecosystem variability, climate change, unspecified anthropogenic perturbation or removal of top predators from trophic networks. Gelatinous plankters, however, are not anomalies in plankton dynamics: the recognition of the ecological importance of their pulses, based on their life cycle patterns (often involving benthic stages), is a critical breakthrough to understand the cycling diversity of plankton in space and time. The current study focuses on the many neglected aspects of the ecology and biology of gelatinous zooplankton, describes how life cycle patterns are central in marine ecology, as are the pulses of gelatinous organisms, and highlights how such a dramatic lack of knowledge can affect our understanding of the marine ecosystem as a whole.
The cubomedusae, well known as the “sea-wasps”, are also notorious because of their voracious feeding habits, F. Conant (1898), who made the first notable study of the biology of cubomedusae, was amazed that Carybdea could capture and swallow relatively large fish., Barnes (1966) who worked on Australian cubomedusae was greatly impressed by the ability of Chiropsalmus and Chironex to consume numerous shrimp of the genus Acetes. Detailed studies of prey capture and transfer, and other aspects of feeding are nonexistent. In fact, except for a few published accounts, such as Southward’s (1955) paper on Aurelia and Smith’s (1936) paper on Cassiopea, no other extensive work has been reported concerning feeding in medusae. In this paper, a comprehensive account of feeding behavior and functional morphology of feeding structures are provided for the cubomedusae, with particular emphasis on Carybdea marsupialis (L.).
The cubopolyp of the box jelly Carybdea marsupialis (L.) reproduces asexually by lateral budding and by almost total transformation of the polyp into a cubomedusa. Buds, one or more at a time, emerge laterally from the body column and separate from the parent as secondary polyps bearing hypostome and some tentacle anlagen. We describe at the light microscopic level the consecutive steps of bud formation and propose to discriminate a series of eight developmental stages. Once detached.. these buds elongate and pass through a vagile phase, creeping over the substratum with the tentacular region ahead. The vagile time period appears to depend on the culture condition; it ends with the firm attachment of the young polyp which then develops the full complement of tentacles along with further growth. The budding rate is positively correlated with the frequency of feeding, in contrast to conditions leading to medusa formation. and is enhanced in the dark. The 'creeping polyp staged reveals a high regeneration potential: both oral and aboral fragments, obtained by midbody transection, regenerate the ablated portion within 72 h. Regeneration in fragments excised from the body column restores also polyp morphology according to the original polar organization. Results of pilot experiments involving excision of the tentacle and hypostomial portion of adult budding and non-budding cubopolyps lead us to discuss a possible interplay between regeneration of oral structures and bud formation.
Although recent articles state that jellyfish populations are increasing, most available evidence shows that jellyfish abundances fluctuate with climatic cycles. Reports of increasing prob- lems with jellyfish, especially in East Asia, are too recent to exclude decadal climate cycles. Jellyfish are infamous for their direct negative effects on human enterprise; specifically, they interfere with tourism by stinging swimmers, fishing by clogging nets, aquaculture by killing fish in net-pens and power plants by clogging cooling-water intake screens. They also have indirect effects on fisheries by feeding on zooplankton and ichthyoplankton, and, therefore, are predators and potential competitors of fish. Ironically, many human activities may contribute to increases in jellyfish populations in coastal waters. Increased jellyfish and ctenophore populations often are associated with warming caused by climate changes and possibly power plant thermal effluents. Jellyfish may benefit from eutrophication, which can increase small-zooplankton abundance, turbidity and hypoxia, all conditions that may favor jellyfish over fish. Fishing activities can remove predators of jellyfish and zooplanktivorous fish com- petitors as well as cause large-scale ecosystem changes that improve conditions for jellyfish. Aquacul- ture releases millions of jellyfish into Asian coastal waters yearly to enhance the jellyfish fishery. Aquaculture and other marine structures provide favorable habitat for the benthic stages of jellyfish. Changes in the hydrological regime due to dams and other construction can change the salinity to favor jellyfish. Accidental introductions of non-native gelatinous species into disturbed ecosystems have led to blooms with serious consequences. In many coastal areas, most of these environmental changes occur simultaneously. We summarize cases of problem jellyfish blooms and the evidence for anthropogenic habitat disruptions that may have caused them. Rapid development in East Asia makes that region especially vulnerable to escalating problems. We conclude that human effects on coastal environments are certain to increase, and jellyfish blooms may increase as a consequence.
This work was started many years ago in the form of a card-index for my own use. At the beginning the building up of the index involved a great deal of work, but later on it saved me time for my studies, and it was not difficult to keep it up to date. One day my friends, Dr F. S. Russell, director of the Marine Biological Laboratory, Plymouth, and Dr W. J. Rees, British Museum (Nat. Hist.), London, saw this index, and they repeatedly urged me to put it into a form suitable for publication for the benefit of other students of medusae. I agreed, though hesitatingly, because my time was much occupied. A grant from the Browne Research Fund of the Royal Society of London, however, enabled me to employ an assistant, Mr J. Liitzen, who under my supervision could carry out the necessary revision and the typing, as well as some translation from Danish or other languages into English; he has done it remarkably well, and I wish to thank him for his industrious and painstaking collaboration.
The clinical characteristics of 40 patients seen in an accident and emergency department after Contact with jellyfish while bathing in the sea are described.