“…In our study, we found highest relative abundances of this dinoflagellate in the western Baltic Sea with salinities above the horohalinicum and only very low relative abundances in the eastern Baltic Proper (eastern Arkona, Bornhom and Gotland Basins). This agrees with the adaptation of P. minimum to salinities above 10 psu salt, but with a capability for short‐term physiological adaptation to the critical salinity zone (Skarlato et al ., ), which raises the question whether salinity changes expected under climate change may in the future repress this non‐indigenous species again.…”
Summary
Remane's Artenminimum at the horohalinicum is a fundamental concept in ecology to describe and explain the distribution of organisms along salinity gradients. However, a recent metadata analysis challenged this concept for protists, proposing a species maximum in brackish waters. Due to data bias, this literature‐based investigation was highly discussed. Reliable data verifying or rejecting the species minimum for protists in brackish waters were critically lacking. Here, we sampled a pronounced salinity gradient along a west–east transect in the Baltic Sea and analysed protistan plankton communities using high‐throughput eDNA metabarcoding. A strong salinity barrier at the upper limit of the horohalinicum and 10 psu appeared to select for significant shifts in protistan community structures, with dinoflagellates being dominant at lower salinities, and dictyochophytes and diatoms being keyplayers at higher salinities. Also in vertical water column gradients in deeper basins (Kiel Bight, Arkona and Bornholm Basin) appeared salinity as significant environmental determinant influencing alpha‐ and beta‐diversity patterns. Importantly, alpha‐diversity indices revealed species maxima in brackish waters, that is, indeed contrasting Remane's Artenminimum concept. Statistical analyses confirmed salinity as the major driving force for protistan community structuring with high significance. This suggests that macrobiota and microbial eukaryotes follow fundamentally different rules regarding diversity patterns in the transition zone from freshwater to marine waters.
“…In our study, we found highest relative abundances of this dinoflagellate in the western Baltic Sea with salinities above the horohalinicum and only very low relative abundances in the eastern Baltic Proper (eastern Arkona, Bornhom and Gotland Basins). This agrees with the adaptation of P. minimum to salinities above 10 psu salt, but with a capability for short‐term physiological adaptation to the critical salinity zone (Skarlato et al ., ), which raises the question whether salinity changes expected under climate change may in the future repress this non‐indigenous species again.…”
Summary
Remane's Artenminimum at the horohalinicum is a fundamental concept in ecology to describe and explain the distribution of organisms along salinity gradients. However, a recent metadata analysis challenged this concept for protists, proposing a species maximum in brackish waters. Due to data bias, this literature‐based investigation was highly discussed. Reliable data verifying or rejecting the species minimum for protists in brackish waters were critically lacking. Here, we sampled a pronounced salinity gradient along a west–east transect in the Baltic Sea and analysed protistan plankton communities using high‐throughput eDNA metabarcoding. A strong salinity barrier at the upper limit of the horohalinicum and 10 psu appeared to select for significant shifts in protistan community structures, with dinoflagellates being dominant at lower salinities, and dictyochophytes and diatoms being keyplayers at higher salinities. Also in vertical water column gradients in deeper basins (Kiel Bight, Arkona and Bornholm Basin) appeared salinity as significant environmental determinant influencing alpha‐ and beta‐diversity patterns. Importantly, alpha‐diversity indices revealed species maxima in brackish waters, that is, indeed contrasting Remane's Artenminimum concept. Statistical analyses confirmed salinity as the major driving force for protistan community structuring with high significance. This suggests that macrobiota and microbial eukaryotes follow fundamentally different rules regarding diversity patterns in the transition zone from freshwater to marine waters.
“…Specifically, as shown recently in the laboratory experiments with P. minimum, high viability of dinoflagellate cells in brackish waters with nonoptimal salinity may be explained (at least in part) by speed up of their metabolic activity under stress (Skarlato et al, 2017). This cellular response may be considered as an effective mechanism which allows the bloom-forming dinoflagellates to dominate in hash environment for the extended periods of time (Skarlato and Telesh, 2017). In particular, the recently demonstrated invasion success of P. minimum in the Baltic Sea (Telesh et al, 2016) was assumed to be largely due to diverse feeding strategies and high intra-population variability of cellular responses to external stress (Matantseva et al, 2016b).…”
Section: Discussionmentioning
confidence: 58%
“…Specifically, as shown recently in the laboratory experiments with P. minimum, high viability of dinoflagellate cells in brackish waters with nonoptimal salinity may be explained (at least in part) by speed up of their metabolic activity under stress (Skarlato et al, 2017). This cellular response may be considered as an effective mechanism which allows the bloom-forming dinoflagellates to dominate in hash environment for the extended periods of time (Skarlato and Telesh, 2017).…”
Section: Discussionmentioning
confidence: 83%
“…Moreover, some dinoflagellate species are successful invaders to new marine environments, and consequences of those invasions often alter ecosystems' structure, functions and biodiversity paradigms (Telesh, 2016;Skarlato and Telesh, 2017). One of the brightest examples is the potentially toxic, mixotrophic, bloom-forming planktonic dinoflagellate Prorocentrum minimum (Pavillard) Schiller, or Prorocentrum cordatum (Ostenfeld) Dodge according to priority rule, and its invasion history in the Baltic Sea.…”
Section: Introductionmentioning
confidence: 99%
“…Within two decades after this invasion, P. minimum had outcompeted its congeners from the complex of dominant dinoflagellate species (Telesh et al, 2016). However, fine mechanisms behind the competitive advantages and pronounced adaptive potential of dinoflagellates are not fully understood (Skarlato et al, 2017).…”
Dinoflagellates are an important group of unicellular eukaryotes widespread in aquatic ecosystems. Many dinoflagellates are mixotrophic, toxic or potentially toxic, highly competitive and invasive, while molecular mechanisms that underpin their success in natural communities remain enigmatic. Due to peculiar features of dinoflagellate genome, little is known about the structure and expression of genes in these organisms. We analyzed the transcriptome databases of the dinoflagellate Prorocentrum minimum in order to identify the sequences of urea transporter (dur3) and nitrate transporter (nrt2.1) genes. Taking into account prospective exon-intron organization of dinoflagellate genome we suggested two variants of choosing the primer positions. We designed six primer pairs for amplification of the urea transporter gene fragments and three-for amplification of the nitrate transporter gene fragments. As a result of PCR, fragments of target genes were obtained. Alignment of amplicons with database transcriptome sequences showed that those sequences were identical. Primers developed in this study can be further used for examination of P. minimum gene expression by RT-qPCR. This approach would provide a better understanding of the influence of various nitrogen sources on physiological characteristics of these protists responsible for their effective adaptations to fluctuating environment.
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