Posters on site: Thu, 1 May, 08:30–10:15 | Hall X5
Gelatinous zooplankton (GZ) has recently been proposed as one of the potential key contributors to the global biological carbon pump, a process that sequesters substantial amounts of CO2 in the deep ocean through sinking organic matter. However, estimates of GZ contributions to global vertical carbon export vary significantly, due to underestimation of GZ abundance and a limited understanding of GZ-derived organic matter release rates, as well as processes affecting vertical GZ export and degradation rates. Here we derive a first dynamically consistent physical model coupling GZ sinking speed to its mass, to provide high-resolution visualization of global vertical transport of GZ-derived carbon. This contrasts with other works, which have used constant sinking speed dynamics. Furthermore, we propose an improvement to microbial decay modeling, where the GZ biomass degradation rate is a function of its area rather than mass. We solved both models, using constant and variable sinking speeds, inside our newly developed Lagrangian particle tracking OpenDrift python environment, which enables numerically fast vertical and horizontal advection of GZ. We use previously published initial GZ-carbon content data and average GZ carcasses sinking speed measurements as our initial speed values. To model the GZ biomass decay, we use published decay rate dependencies and make use of annual climatological temperature fields. We find that, depending on the model, the carbon exports are between (3.83−4.50) Pg C Y-1, (1.53 −2.20) Pg C Y−1 and (0.77 − 1.53) Pg C Y−1 at depths of 100 m, 1000 m and at the seafloor, respectively. In comparison to previous estimates these values are from 8-27 % larger at depths of 100 m, from 16 % lower and up to 20 % larger at depths of 1000 m and from 32 % lower and up to 35 % larger at the seafloor. Finally, we estimate that the inclusion of horizontal advection does not play any major role in the model outcome. This study represents a step towards our understanding of GZ-derived carbon fluxes across ocean depths, the global biological carbon pump and carbon budgets in the ocean.
How to cite: Perharic Bailey, C., Vodopivec, M., Herndl, G. J., Tinta, T., and Licer, M.: Modeling of gelatinous zooplankton related carbon export into the deep ocean , EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-1520, https://doi.org/10.5194/egusphere-egu25-1520, 2025.
Gelatinous zooplankton or 'jellyfish' are present in large numbers in diverse marine ecosystems and, due to their metabolic features and life history traits, some species are capable of generating massive blooms. These blooms often collapse en masse, releasing large quantities of labile proteinaceous organic matter (jelly-OM) that is potentially readily available for microbial degradation in the water column. To test the microbial response to jelly-OM, we simulated, in a two-stage microcosm experiment, the scenario experienced by the coastal pelagic microbiome during a bloom of the invasive ctenophore Mnemiopsis leiydi. In the first stage of our experiment, jelly-OM supported rapid growth of opportunistic bacteria. The jelly-OM degradation was mostly associated with enhanced leucine aminopeptidase, several glycosyl hydrolases and alkaline phosphatase activity and resulted in the accumulation of inorganic nutrients (particularly ammonium). Accordingly, functional annotations of metagenomes recruited from the first stage of our experiment revealed enhanced microbial metabolism of amino acids, lipids and carbohydrates in jelly-OM treatments. In stage two of the experiment, we incubated the processed jelly-OM (i.e., 0.2 µm filtered end-product of microbial processing in stage one) with a fresh microbial plankton assemblage. After 3 days, we observed a significant increase in primary production and phytoplankton biomass, reaching values similar to those observed in situ during seasonal phytoplankton peaks in the region. Observed growth of the phytoplankton community, dominated by diatoms, was likely supported by accumulated ammonia. At the same time, shift in bacterial community composition towards bacterial taxa regularly associated with phytoplankton blooms was observed. Changes in organic matter pool quality and quantity also triggered different metabolic pathways in bacterial communities, in particular those associated with metabolizing carbohydrates. In situ measurements revealed that jellyfish and phytoplankton may be coupled through rapid degradation of jelly-OM by pelagic heterotrophic bacteria. Thus, jellyfish blooms seem to represent a significant source of not only OM but also inorganic nutrients, and may induce major perturbations to ecosystems (e.g., by boosting phytoplankton growth). Considering that gelatinous zooplankton are expected to thrive under projected future changes and increased exploitation of the ocean, our results highlight the necessity to include jellyfish carbon budgets in biogeochemical models of the ocean.
How to cite: Tinta, T., Fadeev, E., Celussi, M., Klun, K., Flander-Putrle, V., Mozetič, P., and Herndl, G. J.: Microbial degradation of jellyfish detritus promotes phytoplankton growth in coastal marine ecosystem, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-1522, https://doi.org/10.5194/egusphere-egu25-1522, 2025.
Jellyfish (gelatinous zooplankton, including Scyphozoa, Cnidaria, and Tunicata) play important roles in marine ecosystems as predators, prey, and contributors to carbon cycling. Their blooms can reshape ecosystem dynamics, alter microbial communities, and, due to rapid sinking detritus, probably present an important component of the biological carbon pump. Despite their ecological significance, observational data on jellyfish abundance and distribution remain scarce, particularly in open waters, as large majority of in situ data are coastal.
Remote sensing offers a promising avenue, but its application is limited. Airplane and unmanned aerial vehicle (UAV) observations provide valuable insights but cover small spatial areas. Current satellite-borne instruments lack the spatial and spectral resolution to directly detect jellyfish. To address this, we utilized laboratory data on jellyfish decay and nutrient release to inform a recently coupled physical-biogeochemical model (CROCO-BFM). The model simulates spatiotemporal phytoplankton response to jellyfish bloom decay, producing sea surface Chlorophyll a (Chl-a) patterns indicative of mass mortality events.
We then analyzed CMEMS (Copernicus Marine Service) multi-satellite daily L3 Chl-a maps (1 km horizontal resolution) using principal component analysis to detect localized Chl-a anomalies. Comparing these anomalies with model predictions and in situ observations allowed us to identify potential matches with jellyfish blooms in the northern Adriatic Sea. This approach highlights the potential of indirect satellite-based methods to track jellyfish bloom dynamics and their ecological impacts on marine ecosystems.
How to cite: Vodopivec, M., Šneberger, N., Faganeli-Pucer, J., and Tinta, T.: Searching for jellyfish from space, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-3032, https://doi.org/10.5194/egusphere-egu25-3032, 2025.
The event-based vision sensors (EVS) are biology-inspired devices designed to capture the detailed movement of objects and are applied as the “eyes” of machines such as factory automation robots. Compared to conventional frame-based image sensors as employed in video cameras, EVS has an extremely fast motion capture equivalent to 10,000-fps even with standard optical settings and additionally has high dynamic ranges for brightness and also lower consumption of memory and energy.
Here, we developed 22 characteristic features for analysing the motions of aquatic particles from the raw data of the EVS and deployed the EVS system in both natural environments and laboratory aquariums to test its applicability to filming and analysing plankton behaviour.
In the session, we will present the results of behavioral analyses of jellyfish and plankton conducted using the EVS in the laboratory, as well as experimental findings from direct observations of biological and non-biological particles, such as plankton, larvae, and sinking aggregates, using the EVS enclosed in a pressure-resistant container.
How to cite: Takatsuka, S., Miyamoto, N., Sato, H., Azumi, H., Hayashi, Y., and Kawagucci, S.: Ocean particle measurement technology using the Event-based Vision Sensor (EVS), EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-3421, https://doi.org/10.5194/egusphere-egu25-3421, 2025.
Jellyfish are considered important predators that play a key role in the organic matter cycling when they occur in blooms. Although their diet can vary spatially and temporally and be species-specific, mesozooplankton are generally recognised as important prey for various macrojellyfish. We present data from a long-term study (1974-2019) comparing the mesozooplankton biomass and blooms of four regularly occurring Scyphozoa species (Aurelia solida, Cotylorhiza tuberculata, Pelagia noctiluca, Rhizostoma pulmo) in the northern Adriatic, and since 2016, also of the invasive Ctenophora Mnemiopsis leidyi. The results showed large inter-annual variations in zooplankton biomass: annual dry mass geomean varied between 9.9 mg/m3 in 2016 and 49.9 mg/m3 in 1992, with 73% of the results below 20 mg/m3, while zooplankton carbon levels ranged between 0.2 and 22.7 mg/m3. In the period 1974-2019, there were years without massive jellyfish blooms and years in which several species occurred "en masse" in different seasons and/or together: A. solida in winter-spring, C. tuberculata in summer, R. pulmo in autumn-winter-spring and M. leidyi in summer-autumn. The Kruskal–Wallis test (p=0.0016) and Dunn's post-hoc multiple pairwise comparison test revealed significant differences in zooplankton biomass between years without blooms or single-species blooms of short duration and those with multi-species blooms with a cumulative duration of > 1 month.
How to cite: Malej, J., Kogovšek, T., Vodopivec, M., Malej, M., and Malej, A.: Macrojellyfish blooms and mesozooplankton biomass: long-term study in the Gulf of Trieste (Adriatic Sea), EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-4991, https://doi.org/10.5194/egusphere-egu25-4991, 2025.
Marine mesozooplankton gather planktonic animals between 0.2 and 20 mm. They are one of the most studied zooplankton size classes and are essential in marine food webs and biogeochemical cycles. In most ocean biogeochemical models, zooplankton are generally represented as size classes, with micro- (<0.2 mm) and meso-zooplankton, overlooking the rest of the functional diversity of marine zooplankton. Yet, studies have shown the key role this diversity can play in ecosystem dynamics. This argues for the need to develop a more precise representation of zooplankton functional diversity by explicitly taking into account additional functional traits, i.e. individual characteristics of organisms that impact their fitness. Among these functional traits, feeding strategy is a poorly studied but key trait that relates to energy intake, predation risk, energetic losses and mate finding.
In this study, we implemented several feeding strategies of mesozooplankton in the ocean biogeochemical model PISCES. Three typical mesozooplankton functional types (PFTs) were considered: cruisers (active swimming feeding on suspension particles), ambushers (passive, relying on a sit-and-wait strategy) and flux-feeders (passively feeding on particle flux). Instead of a classic suspension-feeding (cruisers and ambushers), flux-feeders favor feeding on rapidly sinking particles that would otherwise be transported at depth, directly acting on carbon transfer from the euphotic zone to the mesopelagic.
Simulations have been performed using the NEMO-PISCES model at global scale. Our results highlight the distinct global, regional and vertical distributions of the different groups, with suspension feeders being dominant in the surface layers and flux-feeders being more abundant below the euphotic layer. The different contributions to biogeochemical fluxes is also presented, in particular flux-feeders play a major role in the global carbon cycle, directly impacting the carbon export to deep waters. This work contributes to better understanding the ecology of mesozooplankton at global scale and the role of different feeding strategies in the oceans. Thus, our findings offer new insights on the link between plankton diversity and marine ecosystem functioning and emphasize the necessity for a better integration of mesozooplankton trophic strategies within global biogeochemical models.
How to cite: di Matteo, L., Ayata, S.-D., and Aumont, O.: Trait-based modeling of marine mesozooplankton feeding strategies at the global-scale, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-8035, https://doi.org/10.5194/egusphere-egu25-8035, 2025.
Gelatinous zooplankton ("jellies") have been hypothesized to be the missing link in balancing the current carbon budget mismatch in the "biological carbon pump." During and just after jellyfish bloom events, large amounts of carbon are produced and exported from the euphotic zone via "jelly falls" of dead carcasses and excreted mucous. Due to the patchy nature of these processes, in addition to optical survey tools, a biochemical marker-type approach is needed to provide data integrated over time. Environmental DNA has been found to persist in sediments for time periods greater than one year. The V9 region of the 18S ribosomal DNA gene is one of the most common sequences used for eDNA surveys of whole communities but, currently, GenBank contains fewer than 25 of these sequences from marine jellyfish, with most of these sequences belonging to the Scyphozoan order Coronatae. We report here on our progress in greatly increasing this number, as well as identifying other genes and gene regions that could be exploited for eDNA studies of jellyfishes, particularly for the 16S and COI mitochondrial genes.
How to cite: Lindsay, D., Montenegro, J., Questel, J., Hosia, A., Soto-Angel, J.-J., Martell, L., Jamieson, A., Hopcroft, R., and Collins, A.: Species-specific primer development for identifying the major jellyfish contributors to DNA in the sediments, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-14191, https://doi.org/10.5194/egusphere-egu25-14191, 2025.
Jellies play a fundamental role in the oceans, inhabiting the whole ecosystem from the surface down through the midwater (twilight zone, 50-1000m, and the bathypelagic, 1000-4000m). Recent best estimates suggest that gelatinous zooplankton account for 30% of total plankton biovolume. However, these estimates are most likely a drastic underestimate. A barrier to quantifying the role of jellies in biogeochemical cycles are the currently used sampling techniques. There is a pressing need to accurately quantify the contribution of jellies to biovolume, which is the prerequisite to quantifying their role in biogeochemical cycles. We have been developing platform-agnostic, quantitative imaging systems tailored to enable surveys of jellies from ephyrae size to adult medusae. We have also been developing software pipelines to rapidly process the collected data, with a human-in-the-loop approach for quality control, leveraging recent AI developments to quantify jelly abundances, sizes, biovolumes and diversity.
Currently, the imaging systems we have been developing are centred on colour stereo and shadowgraph-based imaging systems. Colour stereo camera systems can provide size and diversity data on larger animals. Shadowgraphs, on the other hand, can image small plankton and mucoidal/marine snow particles in detail. Since shadowgraphs use collimated light and the recorded images have a generally uniform background, it is easy to detect and quantify particles. Furthermore, internal structures of targets such as jellyfish and mucus can be observed. By using a range of different lenses on shadowgraph systems it becomes possible to simultaneously survey multiple size classes of jellyfishes. We will introduce the hardware prototypes and data processing pipeline as applied to surveys using ROVs and CTD rosettes in deep-sea environments with clear, oceanic water and in the turbid, coastal waters of the Gulf of Thailand from locally-hired fishing vessels and from wharfs.
How to cite: Sangekar, M., Miyake, H., Srinui, K., Giering, S., and Lindsay, D.: Quantitative, multi-scalar in-situ imaging of jellyfishes and jelly-derived particles, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-14359, https://doi.org/10.5194/egusphere-egu25-14359, 2025.
The study of jellyfish blooms, which comprise large amounts of individuals that spread over broad areas, is a multi-scale scientific endeavor. Focusing on seasonal blooms of the scyphozoan jellyfish Rhopilema nomadica in the eastern Mediterranean, we show how integration of remote sensing observations from multiple platforms enables a broad perspective on jellyfish blooms, providng new insights over a wide range of spatial and temporal scales - from the behavior of individuals to the spatial characteristics and biogeochemical importance of the bloom as a whole.
At the smallest scale, jellyfish swimming behavior is characterized through Lagranian tracking the trajectories of multiple adjacent individuals as appear in videos taken by drones hovering over the bloom. Results from this analysis show aggregated jellyfish exhibit distinct directional swimming behavior, which is oriented away from the coast and against the direction of surface gravity waves.
At the regional scale, time varying spatial characteristics of the jellyfish bloom are extracted from aerial images taken from light airplanes. Based on the images we estimate the biomass of the jellyfish comprising the bloom, and characterize the way it is distributed along the coast.
Finally, based on comparison with consecutive satellite images of surface chlorophyll concentrations, which is used as a tracer to transport by the currents, we link the displacement of the jellyfish swarm to fine scale (~1-100 km) circulation patterns.
This research sheds new light on the characteristics of Rhopilema nomadica blooms in the eastern Mediterranean, and emphasises the advantages of incorporating multi-platform remote sensing observations in regional studies of jellyfish blooms worldwide.
How to cite: Lehahn, Y., Berman, H., Malul, D., Lapidot, O., Gray, P., Solodoch, A., Barak, N., Shavit, U., Guy-Haim, T., Lotan, T., Boss, E., Mizrahi, G., and Sher, D.: Characterization of jellyfish movement, distribution patterns and biogeochemical importance using multi-platform remote sensing observations, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-17861, https://doi.org/10.5194/egusphere-egu25-17861, 2025.
Jellyfish blooms occur resulting from redistribution/aggregation events or peaks in population growth. Such blooms can affect ecosystem structure and stability due to the role of jellyfish as top predators of fish larvae and eggs and as competitors of fish preying on the same zooplankton resources. The factors leading to bloom formation have received considerable attention in the past while the factors causing blooms to collapse are less studied so far. However, a better understanding on bloom dynamics is crucial to allow estimates on vertical carbon transport, turnover and flux processes.
In this study, the helmet jellyfish Periphylla periphylla served as a model organism representing a species that causes mass occurrences in several Norwegian fjords thus stimulating debates on potential regime shifts, changes in ecosystem stability and socioeconomic implications.
Here, we used 15-years of trawl data (2006-2015; 2018-2021) complemented with state-of-the art imaging approaches using a remotely operated vehicle (ROV) to study the boom and bust population dynamics of P. periphylla in different areas and seasons in Trondheimsfjorden, Norway. The successful bloom formation of P. periphylla could be attributed to its longevity, dispersal, population connectivity, holoplanktonic life cycle and the lack of natural predators while parasites were identified as potential bloom-controllers thus eventually causing blooms to collapse. The described patterns in jellyfish population dynamics can have substantial effects on the marine carbon cycle by enhancing carbon sequestrations and a subsequent vertical transport to deeper layers of the ocean.
How to cite: Aberle-Malzahn, N., Bakken, T., Martell, L., Volpe, C., Østensen, M.-A., De La Torre, P. R., Skarpnes, A., Svensen, E., and Majaneva, S.: Boom and bust population dynamics of the helmet jellyfish Periphylla periphylla: Implications on carbon fluxes in marine ecosystems, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-18325, https://doi.org/10.5194/egusphere-egu25-18325, 2025.
Posters virtual: Wed, 30 Apr, 14:00–15:45 | vPoster spot 4
EGU25-14703 | Posters virtual | VPS18
Development of an underwater eDNA sampler and its potential application in jellyfish eDNA detectionWed, 30 Apr, 14:00–15:45 (CEST) | vP4.11
We have previously developed a 12-sample environmental DNA (eDNA) sampler designed for use in the marine surface. The sampler can collect and store eDNA samples on filter cartridges according to scheduled sequences. Communicating via mobile phone networks also makes it possible to collect samples on demand. For the underwater eDNA sample-return missions, we have designed and developed a compact eDNA sampler with an oil-filled (pressure-balanced) configuration, enabling its deployment at various depths. Field trials for the underwater eDNA sampler were performed using underwater platforms such as deep-sea landers. Here, we introduce the newly developed compact eDNA sampler and discuss its potential applications in mid- to deep-ocean layers, focusing on eDNA sample-return missions targeting jellyfish and other marine species.
How to cite: Fukuba, T. and Lindsay, D.: Development of an underwater eDNA sampler and its potential application in jellyfish eDNA detection, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-14703, https://doi.org/10.5194/egusphere-egu25-14703, 2025.
