Phylogenetic and functional diversity of Chrysophyceae in inland waters

Abstract

Chrysophyceae are a diverse group of planktonic protists widely distributed in freshwater. They encompass a variety of orders, whereby heterotrophy has evolved independently in several phylogenetic lineages. Therefore, closely related taxa evolved that developed different feeding strategies (photo-, mixo-, heterotrophy). In high-throughput sequencing studies, the Chrysophyceae were usually addressed as a group rather than split in individual phylogenetic orders. Also because of the close relationship of the distinct nutritional strategies, no functional statements were made about nutritional patterns. Based on an extensive phylogenetic tree and phylogenetic placement, we link OTU diversity of Chrysophyceae from 218 freshwater lakes with phylogenetic affiliations. This provides information on the relative importance of lineages affiliated with different nutrition modes. Our study demonstrates that Chrysophyceae are one of the most common groups in freshwaters. We found Chrysophyceae in 213 out of 218 sample sites across Europe and in several sites they belong to the most commonly retrieved taxa. Ochromonadales and a Chrysosacca-Apoikiida clade (including Apoikiida, Chrysosaccales, Chrysastrella) are the most widespread Chrysophyceae groups and show a high degree of OTU diversity. Most detected and assignable OTUs were affiliated with mixotrophic Chrysophyceae. Niche width differs only slightly between members of different clades and between the different trophic modes. We found several OTUs within the Ochromonadales, Synurales, and Chrysosacca-Apoikiida clade, that show a wide distribution and large tolerance ranges concerning ecophysiological factors.

Hibberdia magna (Chrysophyceae): a promising freshwater fucoxanthin and polyunsaturated fatty acid producer

“…When considering FX as a single high-value component of H. magna biomass the following strategies can be considered for the further enhancement of FX productivity: (1) Employing a continuous or semi-batch cultivation mode to utilize the peak of maximal productivity; (2) Media optimization because the sufficiency of nitrogen plays an important role in FX accumulation in microalgae [ 9 ]; (3) Adjusting the photoperiod [ 37 ] or light spectra [ 52 ]; (4) Utilizing mixotrophic growth as the tested strain should be able to take an organic substrate, according to its phylogenetic position [ 53 ]. From above mentioned we have experimentally proved that the light spectrum effects on H. magna FX content, with blue light providing the highest FX content per DW, and purple light providing the highest FX volumetric productivity (Additional file 1 : Fig.…”

Effects of finfish farms on pelagic protist communities in a semi-closed stratified embayment

“…For example, Findlay et al (2009) detected increased abundance of chrysophytes associated with high levels of N and P in a lake heavily stocked with rainbow trout, and Gyrodinium species have been observed to thrive in estuaries with high nutrient inputs from anthropogenic sources such as aquaculture (Wang et al 2017). Chrysophytes and Gyrodinium species have also more generally been associated to humic content and nutrient enrichment (Li, Stoecker & Coats 2000; Pålsson & Granéli 2004) and used as biological indicators to detect environmental changes (Bellinger & Sigee 2015; Bock et al 2022; Gauthier et al 2021; Gökçe 2016; Siver 1995; Xu et al 2010). The abundance of chrysophytes and Gyrodinium species could be related to the presence of humic matter and nutrients concentrations due to riverine and fish farms inputs in the Harbour.…”

“…Chrysophytes and Gyrodinium species have also more generally been associated to humic content and nutrient enrichment (Li, Stoecker & Coats 2000;Pålsson & Granéli 2004) and used as biological indicators to detect environmental changes (Bellinger & Sigee 2015;Bock et al 2022;Gauthier et al 2021;Gökçe 2016;Siver 1995;Xu et al 2010). The abundance of chrysophytes and Gyrodinium species could be related to the presence of humic matter and nutrients concentrations due to riverine and fish farms inputs in the Harbour.…”

Contemporary issues, current best practice and ways forward in soil protist ecology

“…Yet, many taxonomic clades contain both phototrophic and heterotrophic taxa that often cannot be differentiated based on amplicon sequencing data. In soil chrysophyceae, and especially in Ochromonadales, the photosynthetic function has been lost many times independently among closely related lineages (Bock et al, 2022). Furthermore, in soil, most phototrophic protists also consume other organisms or organic molecules.…”