1. Jellyfish mucus-derived organic matter as a source of labile nutrients for the ambient microbial communityNathan Hubot, Sarah L.C. Giering, Neža Orel, Katja Klun, Gerhard J. Herndl, Felix Hohaus, Cathy H. Lucas, Tinkara Tinta, 2026, izvirni znanstveni članek Povzetek: Jellyfish are increasingly recognized as a significant contributor to marine organic matter (OM) on a global scale, with implications for ecosystem dynamics. While the role of jellyfish detritus in microbial nutrient cycling has been explored, the contribution of OM released by live jellyfish—primarily as mucus (hereinafter referred to as mucusassociated OM, or MAOM)—remains understudied. This study investigates the release of organic and inorganic nutrients through MAOM from live jellyfish and their effects on ambient microbial communities in the northern Adriatic Sea using a series of leaching and short-term microcosm experiments. Our results show that per gram of MAOM dry weight from the jellyfish Aurelia spp, approximatively 2 µmol of phosphate, 4 µmol of dissolved inorganic nitrogen, 18 µmol dissolved organic nitrogen, 134 µmol of dissolved organic carbon and 15 µmol of dissolved free amino acids can be released in the ambient seawater in 24 h. Almost half of the OM is released as dissolved OM (DOM), of which a substantial part is low molecular weight (<1 kDa) molecules. During the first 20 h, the DOM fraction of MAOM was rapidly consumed by the ambient microbial community without a corresponding increase in biomass, likely due to nitrogen limitation. In the subsequent 22 h, microbial growth accelerated to 0.19 ± 0.03 h−1 until phosphate became limiting, leading to a sharp decline in microbial production. Our metagenomics analysis revealed that the MAOM-degrading microbial community, dominated by Gammaproteobacteria opportunistic copiotrophs, exhibited increased functional capacity for nutrient assimilation and OM degradation, particularly in the transport and metabolism of amino acids (particularly glycine and taurine) and phosphorus. These traits mirror those found in detritus-degrading microbial communities, suggesting that jellyfish blooms promote the emergence of specialized microbial consortia with shared metabolic capabilities. Taken together, our findings highlight that live jellyfish, through the release of OM, play an active and previously underappreciated role in shaping ambient microbial community dynamics and nutrient fluxes in marine systems affected by jellyfish blooms.
Ključne besede: jellyfish, bacteria, biogeochemistry, metagenome
Objavljeno v DiRROS: 02.03.2026; Ogledov: 480; Prenosov: 48
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2. Data of monitoring the Oplotnica River silicate catchment (Slovenia) using stable carbon and nitrogen isotopesTjaša Kadunc, Stojan Žigon, Daniel Žlindra, Urša Vilhar, Jennifer McIntosh, 22, zaključena znanstvena zbirka raziskovalnih podatkov Povzetek: Herein, we present a dataset of the geochemical and isotopic characteristics of water collected from September 2012 to June 2014 to evaluate biogeochemical processes within the Oplotnica River silicate catchments. Additionally, we collected soil samples at Javorski creek to characterize the soil profiles using stable isotopes of carbon and nitrogen. Discharge and temperature data for the Oplotnica River at the Perovec gauging station were gathered from the Slovenian environment agency. Temperature at both Javorski and Lukanjski creeks was measured on-site, while pH and conductivity were measured in the lab with Metrohm pH low ionic strength glass electrode and Pt1000 electroconductivity electrode, connected to Metrohm 712 Conductometer. Cations (Na+, K+, Ca2+, Mg2+, Mn2+, NH4+) were analyzed with Metrohm Metrosep C4-150/4.0 column without suppression and anions (NO3-, NO32-, SO42-, Cl-, PO43-) with Metrohm Metrosep A Supp 5-150/4.0 column with chemical suppression. Both connected in Metrohm Ion Chromatography modular system. Total alkalinity was measured with double-end point titration (pH=4.5, 4.2) measuring pH with Metrohm pH low ionic strength glass electrode and titrating with 0.01 M HCl controlled by Metrohm 702 SM Titrino titrator. Dissolved organic carbon (DOC) was measured with TOC analyser Shimadzu TOC-5000A as a difference between dissolved total carbon (DTC) and dissolved inorganic carbon (DIC). Thermodynamic modeling was performed with the PHREEQC speciation program to evaluate pCO2 and the saturation state of calcite and dolomite. The major solute composition of the analyzed surface water was as follows: Na+Ca2+Mg2+K+ and HCO3-SO42-Cl-NO3-. In surface water the δ13CDIC ranged from -26.1‰ to -1.4‰, and the 13CPOC from -28.2 to -22.3‰, and 15N from -2.2 to 2.6‰ (measured only in September 2012). 13Corg. ranged from -28.3 to -24.9‰, while 15N ranged from -4.9 to 5.4‰ at three soil profiles (up to a depth of 70 cm) at Tratice I, II and III locations at Javorski creek. Characteristic plants within catchment area have 13C in the range from -31.2 to -29.2‰ and 15N in the range from -8.0 to -5.5‰. Data were collected through field and laboratory analyses. These data were used to calculate saturation indices, partial pressure of CO2 (SIcalcite, SIdolomite, pCO2), and to perform a mass balance calculation of carbon to determine the processes that contribute most to the isotopic composition of dissolved inorganic carbon (δ13CDIC). Furthermore, bicarbonate weathering intensity was calculated within the catchment area. The main conclusions are that the saturation index of calcite (SIcalcite) ranges from -6.1 to -1.9, and the saturation index of dolomite (SIdolomite) ranges from -12.7 to -4.2. The bicarbonate weathering intensity is 10.4 mmol/km²·s, which is typical for silicate catchments.
Ključne besede: isotope Geochemistry, biogeochemistry
Objavljeno v DiRROS: 21.01.2026; Ogledov: 227; Prenosov: 108
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3. Chemical composition and egg production capacity throughout bloom development of ctenophore Mnemiopsis leidyi in the northern Adriatic SeaKevin Rečnik, Katja Klun, Lovrenc Lipej, Alenka Malej, Tinkara Tinta, 2024, izvirni znanstveni članek Povzetek: 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 communities vital to marine biogeochemical cycles. The invasive ctenophores
Mnemiopsis leidyi has formed massive blooms in the northern Adriatic Sea since
2016. However, the variability in the chemical composition and egg production of
blooming populations, as well as the role of environmental factors in governing this
variability, remains largely unknown. Our analysis of biometry, chemical composition,
and fecundity of M. leidyi sampled in the Gulf of Trieste in 2021 revealed stable carbon
and nitrogen content throughout bloom development, with no significant correlation
with seawater temperature, salinity, oxygen, and chlorophyll a concentration. Although
the studied population exhibited homogeneity in terms of biometry and chemical
composition, the number of produced eggs varied substantially, showing no clear
correlation with environmental variables and being somewhat lower than previously
reported for the study area and other Mediterranean areas. We observed a positive
correlation between the wet weight of individuals and the percentage of hatched eggs,
as well as a significant positive correlation between the percentage of hatched eggs
and ambient seawater temperature. Additionally, we noted that the speed of hatching
decreased with decreasing seawater temperature in autumn, corresponding to the end
of M. leidyi bloom.
Ključne besede: ctenophore, biogeochemistry, egg production capacity, invasive species, chemical composition, marine ecology
Objavljeno v DiRROS: 29.08.2024; Ogledov: 1192; Prenosov: 1113
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4. Bacterial degradation of ctenophore Mnemiopsis leidyi organic matterEduard Fadeev, Jennifer H. Hennenfeind, Chie Amano, Zihao Zhao, Katja Klun, Gerhard J. Herndl, Tinkara Tinta, 2024, izvirni znanstveni članek Povzetek: Blooms of gelatinous zooplankton, an important source of protein-rich biomass in coastal waters, often collapse rapidly, releasing large amounts of labile detrital organic matter (OM) into the surrounding water. Although these blooms have the potential to cause major perturbations in the marine ecosystem, their effects on the microbial community and hence on the biogeochemical cycles have yet to be elucidated. We conducted microcosm experiments simulating the scenario experienced by coastal bacterial communities after the decay of a ctenophore (Mnemiopsis leidyi) bloom in the northern Adriatic Sea. Within 24 h, a rapid response of bacterial communities to the M. leidyi OM was observed, characterized by elevated bacterial biomass production and respiration rates. However, compared to our previous microcosm study of jellyfish (Aurelia aurita s.l.), M. leidyi OM degradation was characterized by significantly lower bacterial growth efficiency, meaning that the carbon stored in the OM was mostly respired. Combined metagenomic and metaproteomic analysis indicated that the degradation activity was mainly performed by Pseudoalteromonas, producing a large amount of proteolytic extracellular enzymes and exhibiting high metabolic activity. Interestingly, the reconstructed metagenome-assembled genome (MAG) of Pseudoalteromonas phenolica was almost identical (average nucleotide identity >99%) to the MAG previously reconstructed in our A. aurita microcosm study, despite the fundamental genetic and biochemical differences of the two gelatinous zooplankton species. Taken together, our data suggest that blooms of different gelatinous zooplankton are likely triggering a consistent response from natural bacterial communities, with specific bacterial lineages driving the remineralization of the gelatinous OM.
Ključne besede: jellyfish, proteases, bacterioplankton, ocean biogeochemistry
Objavljeno v DiRROS: 16.05.2024; Ogledov: 1425; Prenosov: 867
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