1. Evaluation of the rbcL marker for metabarcoding of marine diatoms and inference of population structure of selected generaTimotej Turk Dermastia, Ivano Vascotto, Janja Francé, David Stanković, Patricija Mozetič, 2023, original scientific article Abstract: Diatoms are one of the most important phytoplankton groups in the world’s oceans. There are responsible for up to 40% of the photosynthetic activity in the Ocean, and they play an important role in the silicon and carbon cycles by decoupling carbon from atmospheric interactions through sinking and export. These processes are strongly influenced by the taxonomic composition of diatom assemblages. Traditionally, these have been assessed using microscopy, which in some cases is not reliable or reproducible. Next-generation sequencing enabled us to study diversity in a high-throughput manner and uncover new distribution patterns and diversity. However, phylogenetic markers used for this purpose, such as various 18S rDNA regions, are often insufficient because they cannot distinguish between some taxa. In this work, we demonstrate the performance of the chloroplast-encoded rbcL marker for metabarcoding marine diatoms compared to microscopy and 18S-V9 metabarcoding using a series of monthly samples from the Gulf of Trieste (GoT), northern Adriatic Sea. We demonstrate that rbcL is able to detect more taxa compared to 18S-V9 metabarcoding or microscopy, while the overall structure of the diatom assemblage was comparable to the other two methods with some variations, that were taxon dependent. In total, 6 new genera and 22 new diatom species for the study region were identified. We were able to spot misidentification of genera obtained with microscopy such as Pseudo-nitzschia galaxiae, which was mistaken for Cylindrotheca closterium, as well as genera that were completely overlooked, such as Minidiscus and several genera from the Cymatosiraceae family. Furthermore, on the example of two well-studied genera in the region, namely Chaetoceros and particularly Pseudo-nitzschia, we show how the rbcL method can be used to infer even deeper phylogenetic and ecologically significant differences at the species population level. Despite a very thorough community analysis obtained by rbcL the incompleteness of reference databases was still evident, and we shed light on possible improvements. Our work has further implications for studies dealing with taxa distribution and population structure, as well as carbon and silica flux models and networks.
Keywords: rbcL, metabarcoding, monitoring, diatoms, population genetics, Pseudo-nitzschia, Adriatic
Published in DiRROS: 12.07.2024; Views: 2; Downloads: 0
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2. Fitoplankton, model kompleksnostiIvano Vascotto, Patricija Mozetič, Janja Francé, 2024, professional article Keywords: fitoplankton, biološka raznovrstnost, združbe, periodičnost, okoljski dejavniki, Tržaški zaliv, morska biologija
Published in DiRROS: 09.07.2024; Views: 26; Downloads: 9
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3. PETRI-MED: Advancing satellite-based monitoring for microbial plankton biodiversity in the Mediterranean SeaTinkara Tinta, Janja Francé, Katja Klun, Martin Vodopivec, Neža Orel, Patricija Mozetič, Vesna Flander-Putrle, 2024, published scientific conference contribution abstract Keywords: biodiversity, remote sensing, oceanography
Published in DiRROS: 09.07.2024; Views: 30; Downloads: 12
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4. Okadaic acid as a major problem for the seafood safety (Mytilus galloprovincialis) and the dynamics of toxic phytoplankton in the Slovenian coastal sea (Gulf of Trieste, Adriatic Sea)Urška Henigman, Patricija Mozetič, Janja Francé, Tanja Knific, Stanka Grebenc, Jožica Dolenc, Andrej Kirbiš, Majda Biasizzo, 2024, original scientific article Abstract: This article presents the first results on shellfish toxicity in the Slovenian sea (Gulf of Trieste, Adriatic Sea) since the analytical methods for the detection of biotoxins (PSP, ASP, DSP and other lipophilic toxins) in bivalve molluscs were included in the national monitoring program in 2013. In addition to toxins, the composition and abundance of toxic phytoplankton and general environmental characteristics of the seawater (surface temperature and salinity) were also monitored. During the 2014–2019 study period, only lipophilic toxins were detected (78 positive tests out of 446 runs), of which okadaic acid (OA) predominated in 97% of cases, while dinophysistoxin-2 and yessotoxins only gave a positive result in one sampling event each. The number of samples that did not comply with the EC Regulation for the OA group was 17 or 3.8% of all tests performed, all of which took place from September to November, while a few positive OA tests were also recorded in December, April, and May. This toxicity pattern was consistent with the occurrence pattern of the five most common DSP-producing dinoflagellates, which was supported by the development of warm and thermohaline stratified waters: Dinophysis caudata, D. fortii, D. sacculus, D. tripos and Phalacroma rotundatum. The strong correlation (r = 0.611, p<0.001) between D. fortii, reaching abundances of up to 950 cells L−1, and OA suggests that D. fortii is the main cause of OA production in Slovenian waters. Strong interannual variations in OA and phytoplankton dynamics, exacerbated by the effects of anthropogenic impacts in this coastal ecosystem, reduce the predictability of toxicity events and require continuous and efficient monitoring. Our results also show that the introduction of the LC-MS/MS method for lipophilic toxins has improved the management of aquaculture activities, which was not as accurate based on mouse bioassays.
Keywords: biotoxins, okadaic acid, toxic phytoplankton, LC-MS/MS, toxicity, Adriatic Sea, hydrobiology, marine biology
Published in DiRROS: 19.06.2024; Views: 111; Downloads: 55
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5. Exploring the mesoscale connectivity of phytoplankton periodic assemblages' succession in northern Adriatic pelagic habitatsIvano Vascotto, Fabrizio Bernardi Aubry, Mauro Bastianini, Patricija Mozetič, Stefania Finotto, Janja Francé, 2024, original scientific article Abstract: An appropriate model for phytoplankton distribution patterns is critical for understanding biogeochemical cycles and trophic interactions in the oceans and seas. Because phytoplankton dynamics in coastal waters are more complex due to shallow depth and proximity to land, more accurate models applied to the correct spatial and temporal scales are needed. Our study investigates the role of the atmosphere and hydrosphere in pelagic habitat by modelling phytoplankton assemblages at two Long Term Ecological Research sites in the northern Adriatic Sea using niche-forming environmental variables (wind, temperature, salinity, river discharge, rain, and water column stratification). To study the synchronization between the phytoplankton community and these environmental variables at the two LTER sites, we applied current linear and nonlinear numerical methods for ecological modelling. The aim was to use periodic and/or non-periodic properties of the environmental variables to classify the phytoplankton assemblages at one LTER site (Gulf of Trieste - Slovenia) and then predict them at another LTER site 100 km away (Gulf of Venice - Italy). We found that periodicity played a role in the explanatory and predictive power of the environmental variables and that it was more important than non-periodic events in defining the common structure of the two pelagic habitats. The non-linear classification functions of the neural networks further increased the predictive power of these variables. We observed partial synchronization of communities at the mesoscale and differences between the original and predicted assemblages under similar environmental conditions. We conclude that mesoscale connectivity plays an important role in phytoplankton communities in the northern Adriatic. However, the loss of periodicity of niche-forming variables due to more frequent extreme meteorological and hydrological events could loosen these connections and affect the temporal succession of phytoplankton assemblages.
Keywords: phytoplankton, assemblages, Northern Adriatic, phenology, marine biology, hydrobiology
Published in DiRROS: 16.05.2024; Views: 191; Downloads: 258
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7. Ecological time series and integrative taxonomy unveil seasonality and diversity of the toxic diatom Pseudo-nitzschia H. Peragallo in the northern Adriatic SeaTimotej Turk Dermastia, Federica Cerino, David Stanković, Janja Francé, Andreja Ramšak, Magda Tušek-Žnidarič, Alfred Beran, Vanessa Natali, Marina Cabrini, Patricija Mozetič, 2020, original scientific article Keywords: Pseudo-nitzschia, morphology, phylogeny, seasonality, time series, Adriatic Sea
Published in DiRROS: 18.03.2020; Views: 2924; Downloads: 889
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