Presence, abundance and bacterivory of the mixotrophic algae Pseudopedinella (Dictyochophyceae) in freshwater environments

Gerea, Marina; Saad, Juan Francisco; Izaguirre, Irina; Queimaliños, Claudia; Gasol, Josep M.; Unrein, Fernando

doi:10.3354/ame01780

Cited by 19 publications

(24 citation statements)

References 74 publications

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“…Species of the following genera were characterised as mixotrophs: Cryptomonas, Dinobryon, Gymnodinium, Peridinium, Pseudopedinella and Uroglena (Gerea et al, 2016;Sanders, 1991;Tranvik, Porter, & Sieburth, 1989). As an indicator for discriminating between N and P limitation, we used the DIN:TP ratio, which has been identified as the best predictor for phytoplankton nutrient For assessing changes in community composition, species were grouped into chlorophytes, chrysophytes, cryptophytes, cyanobacteria, dinoflagellates and diatoms.…”

Section: Data Preparation and Statistical Analysismentioning

confidence: 99%

Mechanisms preventing a decrease in phytoplankton biomass after phosphorus reductions in a German drinking water reservoir—results from more than 50 years of observation

et al. 2018

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To counteract the severe consequences of eutrophication on water quality and ecosystem health, nutrient inputs have been reduced in many lakes and reservoirs during the last decades. Contrary to expectations, in some lakes phytoplankton biomass did not decrease in response to oligotrophication (nutrient reduction). The underlying mechanisms preventing a decrease in biomass in these lakes are the subject of ongoing discussion. We used a hitherto unpublished long‐term data set ranging from 1961 until 2016 from a German drinking water reservoir (Rappbode Reservoir) to investigate the underlying mechanisms preventing a decrease in biomass. Total phosphorus (TP) concentrations in the Rappbode Reservoir dropped abruptly in 1990 from 0.163 to 0.027 mg/L within three consecutive years, as a result of banning phosphate‐containing detergents. Despite substantial reductions in TP, total annual phytoplankton biomass did not decline in the long‐run, and therefore, the yield of total phytoplankton biomass per unit phosphorus largely increased. Regression analysis revealed a positive association between the yield and potentially phagotrophic mixotrophs (R2 = .465, p < .001). We infer that by ingesting bacteria, mixotrophic species were capable of exploiting additional P sources that are not accessible to obligate autotrophic phytoplankton, eventually preventing a decrease in algal biomass after TP reductions. Long‐term epilimnetic phosphorus concentrations during the winter mixing period decreased to a greater degree than summer phosphorus concentrations. Apparently, TP losses over the season were less intense. Spring diatom biomass also markedly decreased after oligotrophication. In fact, spring diatom biomass was positively related to the TP loss over the season suggesting diatoms play an important role in P reduction. However, this intraannual P processing was not the primary factor when focusing on the average yearly yield, which remained to be fully explained by mixotrophs. Our study demonstrates this ecosystem's ability to compensate for changes in resource availability through changes in phytoplankton community composition and functional strategies. We conclude that an increase in mixotrophy and the ability to make bacterial phosphorus available for phytoplankters were the main factors that allowed the phytoplankton community of the Rappbode Reservoir to adapt to lower nutrient levels without a loss in total biomass.

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Section: Data Preparation and Statistical Analysismentioning

confidence: 99%

Mechanisms preventing a decrease in phytoplankton biomass after phosphorus reductions in a German drinking water reservoir—results from more than 50 years of observation

et al. 2018

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“…, Eckford‐Soper and Daugbjerg , Gerea et al. ). After numerous systematic revisions throughout the twentieth and twenty‐first centuries, the class Dictyochophyceae has been divided into four orders: Dictyochales, Florenciellales, Pedinellales, and Rhizochromulinales (Chang et al.…”

mentioning

confidence: 99%

“…Throughout history, Dictyochophyceae has not been a common research target, possibly due to their low abundance in environmental samples (Gerea et al. ). In recent years, scientific interest in this group has been developing, and the data obtained during the TARA Oceans expedition show that Dictyochophyceae is quite abundant and diverse in global oceans (de Vargas et al.…”

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confidence: 99%

“…Like many other groups of photosynthetic stramenopiles, the Dictyochophyceae exhibits a vast variety of lifestyles, inhabiting both marine and freshwaters as planktonic photosynthetic autotrophs, mixotrophs, and non-photosynthetic bacterivores (Sekiguchi et al 2002, Eckford-Soper and Daugbjerg 2016, Gerea et al 2016. After numerous systematic revisions throughout the twentieth and twenty-first centuries, the class Dictyochophyceae has been divided into four orders: Dictyochales, Florenciellales, Pedinellales, and Rhizochromulinales (Chang et al 2017).…”

mentioning

confidence: 99%

“…After numerous systematic revisions throughout the twentieth and twenty-first centuries, the class Dictyochophyceae has been divided into four orders: Dictyochales, Florenciellales, Pedinellales, and Rhizochromulinales (Chang et al 2017). Throughout history, Dictyochophyceae has not been a common research target, possibly due to their low abundance in environmental samples (Gerea et al 2016). In recent years, scientific interest in this group has been developing, and the data obtained during the TARA Oceans expedition show that Dictyochophyceae is quite abundant and diverse in global oceans (de Vargas et al 2015, Carradec et al 2018, possibly being important planktonic primary producers.…”

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confidence: 99%

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Dictyochophyceae Plastid Genomes Reveal Unusual Variability in Their Organization

Han

Maciszewski

Graf

et al. 2019

Journal of Phycology

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Dictyochophyceae (silicoflagellates) are unicellular freshwater and marine algae (Heterokontophyta, stramenopiles). Despite their abundance in global oceans and potential ecological significance, discovered in recent years, neither nuclear nor organellar genomes of representatives of this group were sequenced until now. Here, we present the first complete plastid genome sequences of Dictyochophyceae, obtained from four species: Dictyocha speculum, Rhizochromulina marina, Florenciella parvula and Pseudopedinella elastica. Despite their comparable size and genetic content, these four plastid genomes exhibit variability in their organization: plastid genomes of F. parvula and P. elastica possess conventional quadripartite structure with a pair of inverted repeats, R. marina instead possesses two direct repeats with the same orientation and D. speculum possesses no repeats at all. We also observed a number of unusual traits in the plastid genome of D. speculum, including expansion of the intergenic regions, presence of an intron in the otherwise non‐intron‐bearing psaA gene, and an additional copy of the large subunit of RuBisCO gene (rbcL), the last of which has never been observed in any plastid genome. We conclude that despite noticeable gene content similarities between the plastid genomes of Dictyochophyceae and their relatives (pelagophytes, diatoms), the number of distinctive features observed in this lineage strongly suggests that additional taxa require further investigation.

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Fluorescently labeled prey surrogates in combination with fluorescence‐activated cell sorting successfully discriminate actively feeding mixotrophs in a lake water sample

Florenza,

Divne,

Bertilsson

2024

Limnology & Oceanography

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Mixotrophic protists are capable of acting both as primary producers and primary consumers at the base of the aquatic food web, thus constituting key organisms in ecosystems where they are abundant. However, their identity, abundance, ecological dynamics, and biogeochemical impact in aquatic ecosystems remain understudied in comparison to classically demarcated autotrophs or heterotrophs. In this study, we make use of fluorescently labeled prey and fluorescence‐activated cell sorting to taxonomically identify actively‐feeding individual mixotrophic flagellates from lake water. Replicated experiments were carried out to assess the performance of three different fluorescently labeled prey types and a fluorescent dye targeting food vacuoles. In the experiments, water from an oligotrophic lake was exposed independently to each type of reporter and cells were individually sorted based on fluorescent signals for predation and chlorophyll a. A total of 927 individual single cells were successfully recovered, with all fluorescent reporters exhibiting high sensitivity for putative mixotrophic taxa: overall, 87% of the occurrences could be assigned to dictyochophytes, 9% to chrysophytes, and 3% to dinoflagellates. As a result, we were able to detect cryptic diversity within pedinellid algae and report a Prorocentrum‐like freshwater occurrence. We argue that this procedure can be a valuable tool to uncover relevant and unexpected active mixotrophic species in a wider range of aquatic environments, and could easily be coupled to other techniques to describe the finer details of the trophic status of aquatic microbial communities.

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Presence, abundance and bacterivory of the mixotrophic algae Pseudopedinella (Dictyochophyceae) in freshwater environments

Cited by 19 publications

References 74 publications

Mechanisms preventing a decrease in phytoplankton biomass after phosphorus reductions in a German drinking water reservoir—results from more than 50 years of observation

Mechanisms preventing a decrease in phytoplankton biomass after phosphorus reductions in a German drinking water reservoir—results from more than 50 years of observation

Dictyochophyceae Plastid Genomes Reveal Unusual Variability in Their Organization

Fluorescently labeled prey surrogates in combination with fluorescence‐activated cell sorting successfully discriminate actively feeding mixotrophs in a lake water sample

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