Publications
To get to know, to discover, to publish—this is the destiny of a scientist.— François Arago
Successful acclimation of marine diatoms Chaetoceros curvisetus/ pseudocurvisetus to climate change
A new pubblication came out in Limnology and Oceanography by Vrana et al. in 2022 about acclimation of marine diatoms to climate change.
Abstract: Two main parameters that structure the marine ecosystem by affecting species distribution, abundance, community structure, timing of major life cycle events, and trophic state of the ecosystem are temperature and nutrient availability. Faced with climate change, eukaryotic plankton cope at multiple levels through physiological accommodation, adaptive evolution, shift in time and/or space of habitat, and/or community responses. Thirty‐two years of our phytoplankton research indicate that Chaetoceros curvisetus/pseudocurvisetus adjust to climate change more successfully than the majority of the accompanying phytoplankton taxa in the mesotrophic part of the NW Adriatic Sea, the Mediterranean. While the abundance of the entire accompanying phytoplankton community has decreased significantly since 2003 (the period of the northern Adriatic warming and oligotrophication) compared to the previous period (1986–2003), the abundance of C. curvisetus/pseudocurvisetus remained unchanged, while its contribution to the community increased significantly. Accommodation strategies include a change in the timing of high abundance and blooms in the surface layer and successful blooming in the deeper layers during warm months. Apart from the observed in situ accommodation, physiological acclimation to warming may involve changes in photosynthesis, respiration, growth, and cell biochemistry. Here, we conducted laboratory experiments with C. pseudocurvisetus to investigate how warming affects its biochemical response through the fatty acid remodeling of phospholipid classes. Long‐term field observations and short‐term laboratory experiments suggest that marine diatoms C. curvisetus/pseudocurvisetus are potential global winners with the ability to acclimate/adapt to climate change.
Characterisation and toxicological activity of three different Pseudo-nitzschia species from the northern Adriatic Sea (Croatia)
Diatoms of the genus Pseudo-nitzschia are cosmopolitans spread in seas and oceans worldwide, with more than 50 described species, dozens of which have been confirmed to produce domoic acid (DA). Here, we characterized and investigated the toxicological activity of secondary metabolites excreted into the growth media of different Pseudo-nitzschia species sampled at various locations in the northern Adriatic Sea (Croatia) using human blood cells under in vitro conditions. The results revealed that three investigated species of the genus Pseudo-nitzschia were capable of producing DA indicating their toxic potential. Moreover, toxicological data suggested all three Pseudo-nitzschia species can excrete toxic secondary metabolites into the surrounding media in addition to the intracellular pools of DA, raising concerns regarding their toxicity and environmental impact. In addition, all three Pseudo-nitzchia species triggered oxidative stress, one of the mechanisms of action likely responsible for the DNA damage observed in human blood cells. In line with the above stated, our results are of great interest to environmental toxicologists, the public and policy makers, especially in light of today's climate change, which favours harmful algal blooms and the growth of DA producers with a presumed negative impact on the public health of coastal residents.
Morpho‑physiological adaptations of Leptocylindrus aporus and L. hargravesii to phosphate limitation in the northern Adriatic
Focus of this study is on two Leptocylindrus species, Leptocylindrus aporus (F.W. French & Hargraves) D. Nanjappa & A. Zingone 2013 and Leptocylindrus hargravesii D. Nanjappa & A. Zingone 2013. Species belonging to Leptocylindrus genus are frequently observed and have high abundances and also high contributions to the microphytoplankton community in this area. We focused on their morphological and physiological responses to phosphate limitation in situ and also performed in vitro experiments. In this study we report data on species specifc growth rates under phosphorus (P) deplete and P rich conditions, localization and characteristics of alkaline phosphate activity, phosphate uptake rates as well as their morphological diferences in P deplete versus P rich conditions. Our in vitro experiments showed that both Leptocylindrus species morphologically reacted similarly to phosphorus depletion and showed signifcantly elongated pervalvar axis in P depleted conditions if compared to P rich conditions. Also average chain lengths increased when in P depleted conditions. Two previously mentioned adaptations indicate their tendency to increase cellular surface areas available for alkaline phosphatase. Chlorophyll fuorescence of both species signifcantly decreased in P depleted medium. Although both species morphologically reacted similarly, our experiment demonstrated signifcant diferences in physiological reactions to P depleted conditions
Physiological adaptations of
Chaetoceros danicus to phosphate limited
environmental conditions
Chaetoceros danicus Cleve, a planktonic marine diatom species from the Phaeoceros subgenus, is usually a single celled organism, but can also form short chains of two or three cells Distributed worldwide, with low aboundances rarely dominating diatom community Cells are composed of cell body and setae that originate on body margins Numerous plastids are located in the central body and in the setae. We observed morphological changes of C danicus grown in P limited medium Setae of cells in P limited medium became
significantly thicker and longer than setae of those in F/ 2 medium ..(Fig 5 Growth rates were higher in F/ 2 medium, compared to P limited medium ..(Fig 3 Differences were observed in cellular AP activity, with growing activity in P
limited medium, while in the F/ 2 medium activity remained
low ..
Barcoding 130 diatom cultures for the 130 years anniversary
Introduction
On May 10th 1891, 130 years ago, the current Center for Marine Research, Ruder Boskovic Institute (CMR-IRB), was founded as a marine station of the Berlin Zoo and Aquarium (Zoologischer Garten und Aquarium KG, Berlin, Germany) under the name “Station des Berliner Aquariums, Rovigno d’Istria” and was situated on the coast of the northern Adriatic Sea in Rovinj, Croatia. During its long-time history of marine research, phytoplankton diversity has been continuously in the scientific focus of the CMR-IRB. Diatoms as the most abundant phytoplankton group in the Northern Adriatic (NA) are composed of around 500 recorded species3. In the CMR-RBI, traditional methods based on light-microscopy were commonly used for the diatom species identification. Following recent trends, CMR-RBI successfully applied new, molecular methods that enable fast and reliable species identification through DNA barcoding. DNA barcode is an universally accepted short DNA sequence, usually around 700 bp, used for identification of species1, diatoms included2. To mark the CMR-IRB 130th anniversary, our barcoding project included barcoding of 130 single-cell diatom cultures from the CMR-IRB culture collection and phylogeny based taxonomic assignment with the aim of building species diverse and sequences reliable diatom barcodes database of the NA.