Journal Of Phycology[JOURNAL]
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200 papers
The YEATS domain containing protein PyYEATS functions as a histone acetylation reader in the red seaweed Pyropia yezoensis.
Pang Y, Tang F, Pozas J … +9 more , Barrero-Gil J, Piñeiro M, Jarillo JA, Mao X, Zhang X, Cao X, Zhang Z, Mao Y, Wang D
J Phycol · 2025 Jun · PMID 40465095 · Publisher ↗
Pyropia yezoensis, a key economic marine crop in Asia, serves as a model for red seaweed research. Previously, we determined that histone acetylation plays essential roles in the response to abiotic stresses and the form...
Pyropia yezoensis, a key economic marine crop in Asia, serves as a model for red seaweed research. Previously, we determined that histone acetylation plays essential roles in the response to abiotic stresses and the formation of asexual spores in P. yezoensis. However, the reader proteins of acetylated histones remain to be identified. In this study, we characterized the gene encoding a YEATS domain-containing protein (PyYEATS) in P. yezoensis. The PyYEATS protein, mainly localized in nuclei with a small amount in cytosolic fractions in thalli, harbored a classic YEATS domain followed by a coiled-coil domain at the C-terminal. This locus exhibited conservation in domain structure compared with its homologs in other red algae and showed a closer relationship to animal GAS41 counterparts than plant YAFs. In vitro assays showed that the PyYEATS protein preferentially binds H3K14ac, H3K18ac, and H4K5ac and that the F105, W124, and F127 residues in the YEATS domain are essential for its affinity to these histone acetylation sites. Y2H and GST-pulldown approaches revealed an interaction of PyYEATS with S-adenosyl-L-homocysteine hydrolase (SAHase), eukaryotic translation initiation factor 3 (eIF3), and actin, among others, suggesting possible extra-transcriptional functions for PyYEATS. Finally, we observed that the transcript levels of this gene significantly increased after wounding in P. yezoensis thalli, pointing out a potential role in the P. yezoensis stress response. Our findings provide important insights into the evolution of chromatin readers of histone acetylation in red seaweeds and help to shed light on the biological function exerted by PyYEATS in this species.
Revisiting the species problem in Northeast Pacific ribbon kelp lineages (genus Alaria): Lessons learned using whole genome data.
Bringloe TT, Grant WS, Zaparenkov D … +6 more , Starko S, Fort A, Inaba M, Sulpice R, Saunders GW, Verbruggen H
J Phycol · 2025 Aug · PMID 40454788 · Full text
The transition from interbreeding populations to species continues to represent difficult terrain for phylogenetic investigations. Genotyping entire genomes holds promise for enhancing insights into the process of specia...
The transition from interbreeding populations to species continues to represent difficult terrain for phylogenetic investigations. Genotyping entire genomes holds promise for enhancing insights into the process of speciation and evolutionary relationships among recently speciated taxa. Northeast Pacific ribbon kelp was once recognized as four species before they were folded into Alaria marginata based on DNA barcodes, although several lineages continue to be recognized. We used whole genome sequencing to determine whether these lineages represente species. Whole genomes of 69 individuals from five genetically distinctive lineages in the Gulf of Alaska (United States) and Salish Sea (Canada) were analyzed, along with 63 genomes from three other species of Alaria. Our analysis of >3.4 million single nucleotide polymorphisms reaffirmed that organellar and nuclear phylogenetic signals are incongruent in Alaria, producing different topologies among five organellar and six nuclear A. marginata lineages. Lineages appeared to be reproductively isolated, as evidenced by strong clustering and lack of recent admixture across nuclear genomes. Genetic divergence between A. marginata lineages also exceeded intra-lineage divergence, proxied by A. esculenta populations, but fell short of distances observed across other species of Alaria. Despite the genomic data supporting predictions of the biological and genetic species concepts, we encountered inherent limitations in declaring species status. While our work shifts taxonomic conversations toward a genome-scale framework that provides a more comprehensive picture of divergence and connectivity, our work also highlights that philosophical challenges inherent to defining species persist and that integrative approaches continue to be necessary in the genomic era.
No dewfall or frost in the Antarctic Dry Valley summers: Comment on Büdel et al. (2008).
Kidron GJ, Beysens D, McKay CP
J Phycol · 2025 Aug · PMID 40454751 · Publisher ↗
Microbial communities within porous rocks in the upper elevations of the McMurdo Dry Valleys of Antarctica are an interesting analog for life on Mars. The primary source of moisture for this community is summer snowmelt...
Microbial communities within porous rocks in the upper elevations of the McMurdo Dry Valleys of Antarctica are an interesting analog for life on Mars. The primary source of moisture for this community is summer snowmelt adsorbed by the porous stone. Büdel et al. (2008) suggested that dewfall/frost may be an alternative and frequent source of water, implying that in comparison to other prokaryotic communities in which the apparent use of dew by prokaryotes was challenged (cyanobacterial soil biocrusts and lithic cyanobacteria in the Negev), this community stands out as one that presumably utilize dew/frost. By assuming the utilization of a frequent source of water, the authors concluded that this community cannot be regarded as inhabiting the "edge of life" as often suggested. Nevertheless, over almost 50 years of investigation of these systems, this is the only report of dew/frost in the summer. We believe that this report is in error due to faulty temperature measurements of the rock surface and miscalculation or misuse of the condensation theory.
Investigation of coastal benthic diatom communities using the rbcL marker with nanopore sequencing in urban marine environments.
Kaleli A, Ozbayram EG, Zengin Z … +1 more , Akcaalan R
J Phycol · 2025 Aug · PMID 40448515 · Publisher ↗
Marine benthic diatoms are one of the most important groups in coastal primary production and photosynthesis, and the number of molecular studies revealing diatom biodiversity is increasing. In this study, we investigate...
Marine benthic diatoms are one of the most important groups in coastal primary production and photosynthesis, and the number of molecular studies revealing diatom biodiversity is increasing. In this study, we investigated diatom composition using environmental DNA metabarcoding based on the rbcL gene using MinION (Oxford Nanopore) at 11 sampling sites along the Istanbul coasts of the Sea of Marmara in 2023. We identified 261 species belonging to 121 genera, and among them, Nitzschia (19.6%; 24 species) and Navicula (17.1%; 21 species) were the most abundant genera, followed by Licmophora (6.9%) and Nanofrustulum (6.1%). At the species level, the highest number of reads was assigned to Nitzschia inconspicua, Navicula perminuta, and Nanofrustulum shiloi. Redundancy analysis (RDA) showed that pH was the major driving factor related to taxon abundance at the genera and species levels. Metabarcoding results revealed the presence of new taxa for the Sea of Marmara such as Minutocellus, Pierrecomperia, Perideraion, Rhoikoneis, Sternimirus, and Synedropsis, which had not been formerly detected by traditional monitoring methods. Since there are few studies on marine diatom monitoring using rbcL gene markers, our results could support the use of this marker to reveal the diversity of marine benthic diatoms from urban coasts.
The Great Barrier Reef, a center for Pelagophyceae (Heterokontophyta) diversity, including a new genus and seven new species.
Wetherbee R, van de Meene A, Hossen R … +2 more , Andersen RA, Verbruggen H
J Phycol · 2025 Jun · PMID 40434376 · Full text
The pelagophytes are a morphologically diverse class of marine heterokont algae defined by deoxyribonucleic acid (DNA) gene sequences, the presence of a multilayered, perforated theca (PT), and the novel role of the Golg...
The pelagophytes are a morphologically diverse class of marine heterokont algae defined by deoxyribonucleic acid (DNA) gene sequences, the presence of a multilayered, perforated theca (PT), and the novel role of the Golgi apparatus in the formation and secretion of the PT, as well as materials for the synthesis of the outer extracellular layers (e.g., cell walls and mucilage). We established clonal cultures of sand-dwelling pelagophytes collected from intertidal and subtidal locations at Heron Island on the Great Barrier Reef (GBR), Australia, and established phylogenetic trees based on nuclear 18S rDNA and plastid rbcL, psaA, psaB, psbA, and psbC gene sequences that led to the discovery of seven new species and several interesting range extensions. The new genus and species, Revolvomonas australis, is sister to Pituiglomerulus and Chrysocystis in the Chrysocystaceae (Sarcinochrysidales, Pelagophyceae). Additional new species are Sarcinochrysis kraftii, Sa. guiryi, Arachnochrysis pilardiaziae, A. cassiotisii, Sungminbooa capricornica, and Su. tropica; also identified and cultured from the GBR were Sa. marina, Aureoumbra geitleri, Chrysoreinhardia giraudii, Chrysocystis fragilisi, and the planktonic Pelagomonas calceolata. Revolvomonas was studied in detail and has several unusual features for sand-dwelling pelagophytes. In just three short collecting trips to Heron Island, we were able to isolate and identify over 40% of the pelagophyte genera discovered to date. This study substantiates the diverse nature of pelagophytes and suggests tropical reef sand may be a center for pelagophyte diversity.
Abiotic stress destabilizes the bacterial community of sugar kelp, Saccharina latissima (Phaeophyceae).
Schenk S, Wardrop CG, Parfrey LW
J Phycol · 2025 Aug · PMID 40432552 · Full text
As climate change progresses, the intensity and variability of freshwater outflow into the ocean are predicted to increase. The resulting increase in low-salinity events, paired with other abiotic stressors (including in...
As climate change progresses, the intensity and variability of freshwater outflow into the ocean are predicted to increase. The resulting increase in low-salinity events, paired with other abiotic stressors (including increasing temperatures), will be a source of stress for the kelp Saccharina latissima (Saccharina hereafter) and potentially Saccharina-associated bacteria. Bacteria influence host health and can facilitate or hinder host survival and acclimation to stressful abiotic conditions. Therefore, understanding how bacterial communities change under abiotic stress is critical for understanding how abiotic stress will affect kelp physiology. We investigated the effect of abiotic stress on Saccharina and associated bacteria by surveying the bacterial community associated with Saccharina across naturally occurring salinity and temperature gradients, coupled with salinity manipulation experiments. Overall, Saccharina harbored a stable core bacterial community, which decreased in relative abundance under abiotic stress. In the field, both salinity and temperature shaped the bacterial community, with temperature having higher explanatory power most of the time. In the lab, we confirmed that the patterns observed in the field could be replicated by manipulating salinity alone. Decreased relative abundance of core bacteria and increased community dissimilarity in low-salinity in the lab suggest that low-salinity alone can induce a stress response, detectable in the bacterial community of Saccharina.
A systematic review of marine macroalgal degradation: Toward a better understanding of macroalgal carbon sequestration potential.
Kennedy JR, Blain CO
J Phycol · 2025 Jun · PMID 40423688 · Full text
Although macroalgae are gaining recognition for their potential role in marine carbon sequestration, critical knowledge gaps related to the fate of macroalgal carbon limit our capacity to quantify rates of macroalgal car...
Although macroalgae are gaining recognition for their potential role in marine carbon sequestration, critical knowledge gaps related to the fate of macroalgal carbon limit our capacity to quantify rates of macroalgal carbon sequestration. Understanding the degradation dynamics of macroalgal-derived biomaterials-including tissue/wrack, particulate organic matter/carbon (POM/POC), and dissolved organic carbon (DOC)-as well as the environmental drivers of decomposition are critical for assessing the longevity of macroalgal carbon and the potential storage capacity of macroalgae. Thus, a systematic literature review of macroalgal degradation studies was conducted to compile data, estimate the relative recalcitrance (i.e., relative stability) of macroalgal biomaterials, and elucidate key drivers of macroalgal decomposition dynamics. We found that macroalgal decay trajectories are highly variable and not always best described by the often-cited exponential decay models. Our analysis demonstrated that temperature was a notable driver of decomposition, with higher temperatures eliciting faster rates of decomposition. Furthermore, we found that brown algae had significantly higher proportions of recalcitrant biomaterials when compared to red algae. The impact of other factors, including biomaterial type, degradation environment, and tissue carbon and nitrogen content on macroalgal degradation, is variable across contexts, warranting further study. These results help to provide a foundation from which to plan and assess future studies on macroalgal degradation, which will improve our understanding of how macroalgae contribute to marine carbon cycles, trophic subsidies, and, potentially, marine carbon sequestration.
Taxonomy of the genus Poterioochromonas (Chrysophyceae) based on morphological and molecular evidence.
Jeong M, Kim JI, Shin W
J Phycol · 2025 Jun · PMID 40418188 · Full text
The genus Poterioochromonas is characterized by spherical cells having two unequal flagella, a greenish, yellow-brown plastid, and a hemispherical cup-shaped lorica with a long, narrow stalk and a foot anchoring to the s...
The genus Poterioochromonas is characterized by spherical cells having two unequal flagella, a greenish, yellow-brown plastid, and a hemispherical cup-shaped lorica with a long, narrow stalk and a foot anchoring to the substrate. In this genus, the only three mixotrophic species having plastids have been reported up to date: P. malhamensis, P. nutans, and P. stipitata. However, we observed heterotrophic Poterioochromonas species that had lost their plastids, and we successfully cultured them. To understand the taxonomy of Poterioochromonas species, we performed a molecular phylogenetic analysis and observed their morphological features using light and scanning electron microscopes. For the phylogenetic analysis, we used a combined dataset from five gene sequences: the nuclear small subunit (SSU) rRNA gene, the large subunit (LSU) rRNA gene, the internal transcribed spacer region (ITS rRNA region 1-5.8S-ITS2), the plastid LSU rRNA gene, and the rbcL gene. The molecular phylogeny of the genus Poterioochromonas was divided into two major clades: mixotrophic and heterotrophic lineages. The mixotrophic clade comprised three species including two new species-P. andersenii sp. nov. and P. longicaulis sp. nov.-characterized by a colonial lifestyle and the long stalk of the lorica. The heterotrophic clade included the four new species-P. amplexa sp. nov., P. communis sp. nov., P. similis sp. nov., and P. sinechrysos sp. nov.-that had lost their plastids. The species P. amplexa produced a very distinctive stomatocyst, which features a true complex collar. Here, we report six new species of Poterioochromonas that exhibit mixotrophy and heterotrophy, showing that the phylogenetic tree is distinctly divided according to nutritional modes.
Monoicy, dioicy, and genetic structure in three species of Sheathia (Batrachospermales, Rhodophyta).
Shainker-Connelly SJ, Stoeckel S, Vis ML … +1 more , Krueger-Hadfield SA
J Phycol · 2025 Aug · PMID 40418119 · Full text
Sexual systems (i.e., separate vs. combined sexes) vary widely among eukaryotes and influence the evolution of reproductive systems, which shape genetic structure and evolutionary trajectories. In diploid-dominant angios...
Sexual systems (i.e., separate vs. combined sexes) vary widely among eukaryotes and influence the evolution of reproductive systems, which shape genetic structure and evolutionary trajectories. In diploid-dominant angiosperms, combined (i.e., hermaphroditism) and separate sexes are expected to correlate with selfing and outcrossing, respectively. When sex is determined in the haploid phase, selfing is possible even when there are separate sexes. The freshwater red macroalgal genus Sheathia (Batrachospermales) displays sexual system variation within and among populations, but no prior data exist on the reproductive systems of these populations. We developed 16 polymorphic microsatellite loci to characterize the reproductive system and genetic structure of three Sheathia species. We observed cross-amplification of loci across the three targeted species, suggesting these markers may be useful in other Sheathia spp. We observed variation in monoicy (i.e., hermaphroditism) versus dioicy (i.e., separate sexes) in each species, including S. americana, which was previously believed to be obligately dioicous. Our data suggest that S. americana and S. involuta display more variation in their prevailing reproductive modes as compared to S. grandis. Generally, dioicy resulted in greater diversity in contrast to monoicy. We observed strong population structure that is likely driven by uniparental reproduction and limited dispersal; however, there is limited population connectivity that may be facilitated by long-distance dispersal events. Overall, these data contribute to our knowledge of the relationship between the sexual system, reproductive system, and population genetic structure in haploid-diploid taxa, thereby informing a broader understanding of the evolution of sex.
Green gold rush in the Baltic Sea: Investigating sea lettuce's performance by distribution mapping of valuable compounds in a fluctuating environment.
Steinhagen S, Schrofner-Brunner E, Schrofner-Brunner B … +2 more , Larsson K, Undeland I
J Phycol · 2025 Jun · PMID 40396569 · Full text
The growing prominence of Ulva in aquaculture is driven by its adaptability, rapid growth, nutritional advantages, and diverse biochemical composition. These green macroalgae have gained increasing attention for cultivat...
The growing prominence of Ulva in aquaculture is driven by its adaptability, rapid growth, nutritional advantages, and diverse biochemical composition. These green macroalgae have gained increasing attention for cultivation in lower salinity areas, expanding aquaculture beyond traditional euhaline environments. Our study investigated the distribution of economically valuable compounds in the most prominent Ulva crop species of the wider Baltic Sea region. We included 249 populations across the full Atlantic-Baltic Sea transect (>3000 km) and took into account prevailing fluctuating abiotic factors like salinity and nutrient regimes during the vegetation peak season. We revealed an overall trend of increasing crude protein content with increasing salinity in species with occurrence along the whole Atlantic-Baltic Sea transect (U. intestinalis: slope = 0.29; U. linza: slope = 0.09) and those only present in higher salinity regions (U. compressa: slope = 0.36; U. fenestrata: slope = 0.18) and confirmed an increase of pigments with increasing nitrogen tissue levels for most species (U. compressa: r = 0.43; U. fenestrata: r = 0.01; U. intestinalis: r = 0.13; U. linza: r = 0.21). With this mapping of the resource availability of valuable compounds in natural Ulva biomass of the Baltic Sea region, we have contributed to the understanding of the potential of Ulva species as key players in sustainable aquaculture practices evolving in the Baltic Sea region. Further, we have underscored the necessity of habitat-dependent crop selection and the importance of horticulture methodology for establishing Ulva as a viable future crop in the wider Baltic Sea.
Selecting functional traits that capture trade-offs for intertidal macroalgae provides a roadmap for future studies.
Smith LL, Grier SR, Fong P
J Phycol · 2025 Aug · PMID 40353831 · Publisher ↗
Increased impacts from anthropogenic stressors are motivating the search for novel tools and approaches to understand ecosystem shifts and community change. Although trait-based approaches have provided powerful tools fo...
Increased impacts from anthropogenic stressors are motivating the search for novel tools and approaches to understand ecosystem shifts and community change. Although trait-based approaches have provided powerful tools for many taxa, the functional ecology of marine macroalgae remains rooted in functional group models from the 1980s. Thus, we sought a core set of macroalgal traits to capture the diversity of ecological strategies that maintain ecological functions in a changing ocean. We first measured and analyzed a large number of functional traits to capture ecological strategies, and then used quantitative methods and examined the literature to select six core traits that captured the same strategies. We chose rocky intertidal sites, as they compress large shifts in environmental drivers into a small spatial scale, and chose seven morphologically diverse species collected across habitats and seasons. Permutational multivariate analyses of variance that included either 16 or six traits both determined significant differences across traits among species, with nearly equal explanatory power. In both data sets (16 vs. six traits), we discovered a resource acquisition trade-off along an axis of variation that maximizes either thallus height to facilitate resource acquisition by preemptive capture or relative surface area to increase uptake efficiency when lower resource supplies are available. Being taller, however, requires strength to resist disturbance (drag), whereas individuals with more surface area are shorter and weaker. Thus, we posit only six core traits are needed to capture ecological strategies for intertidal macroalgae in this rocky intertidal system, streamlining future research. Our results provide a roadmap for selecting traits that can rapidly advance exploration of trait-based ecology in other macroalgal-dominated ecosystems, providing a strong foundation to continue developing trait-based ecology for macroalgae across systems.
Assessment of the spatial distribution of Chondria tumulosa, a nuisance macroalga at Manawai in Papahānaumokuākea Marine National Monument using high-resolution satellite imagery.
Beyer L, Miura T, Fraiola K … +5 more , Spalding HL, Williams TM, Martinez J, Kosaki RK, Lopes KH
J Phycol · 2025 Jun · PMID 40353826 · Full text
In 2019, a red macroalgal species, Chondria tumulosa, was discovered overgrowing native coral and algal species and changing the benthic communities of Manawai (Pearl and Hermes Atoll) in Papahānaumokuākea Marine Nationa...
In 2019, a red macroalgal species, Chondria tumulosa, was discovered overgrowing native coral and algal species and changing the benthic communities of Manawai (Pearl and Hermes Atoll) in Papahānaumokuākea Marine National Monument (PMNM). The main objective of this study was to assess the spatial distribution of C. tumulosa across the forereef and backreef of Manawai using satellite remote sensing. WorldView-2 and -3 commercial high-resolution satellite images were obtained for a 12-year period from 2010 to 2021, from which, time-series animations were created. Previous studies reported that C. tumulosa appeared as distinctively dark features in satellite imagery with the first evidence of C. tumulosa in 2015. Thus, the animations were visually inspected to identify dark patches that became visible around the time of discovery and persisted in subsequent years. Field survey data of C. tumulosa cover collected in 2019-2021 were used to gain confidence in the identification of dark patches. Using those dark features as a reference and a support vector machine, the latest high-resolution satellite images from the 12-year period were classified into a map of distinctive dark patches suspected to be C. tumulosa with an average overall accuracy of 78%. Accuracy assessments of the classification results of C. tumulosa based on field survey data collected in 2019-2021 resulted in an overall accuracy of 79%. This study leverages the use of remote sensing to map a newly discovered alga in a remote area in the hopes of providing managers with a methodology to further monitor the species for long-term management.
Recruitment of intertidal kelps Hedophyllum sessile and Alaria marginata (Laminariales) to articulated and crustose coralline algal species.
Burns R, Twist BA, Martone PT
J Phycol · 2025 Jun · PMID 40326705 · Full text
Kelps and coralline algae are important primary producers and habitat-builders in rocky intertidal ecosystems. On wave-exposed shores along the west coast of North America, Hedophyllum sessile and Alaria marginata are tw...
Kelps and coralline algae are important primary producers and habitat-builders in rocky intertidal ecosystems. On wave-exposed shores along the west coast of North America, Hedophyllum sessile and Alaria marginata are two dominant kelp species with juveniles that often occur at a higher density on articulated corallines than other available substrates. Little is known of the mechanisms underlying this interaction. One hypothesized mechanism is that articulated coralline algae enhance kelp spore settlement and germination. This study tested this hypothesis by releasing spores from H. sessile and A. marginata onto multiple genetically identified articulated and crustose coralline species, as well as bare rock, then observing subsequent sporophyte densities. Kelp recruitment was generally higher on articulated corallines than on crustose corallines, although there was variation across coralline species. There was no significant difference between recruitment on bare rock and on articulated corallines, and recruitment was higher on bleached Corallina vancouveriensis than on live C. vancouveriensis, suggesting that this articulated coralline actively inhibits rather than promotes intertidal kelp settlement. Thus, other mechanisms, such as protection from herbivory or wave action, likely explain observed distributions of kelp recruits. This research contributes to understanding how the fine-scale distribution of kelps is linked to that of corallines.
Isolation and characterization of a spore development mutant in Pyropia yezoensis (Rhodophyta) induced via insertional mutagenesis.
Izumi H, Nakai Y, Uji T … +4 more , Nagaosa K, Fukuda S, Mizuta H, Saga N
J Phycol · 2025 Aug · PMID 40323712 · Full text
Mechanistic elucidation of spore development is essential for understanding reproductive strategies and improving seaweed cultivation. In this study, we isolated a mutant with spore development defects in Pyropia yezoens...
Mechanistic elucidation of spore development is essential for understanding reproductive strategies and improving seaweed cultivation. In this study, we isolated a mutant with spore development defects in Pyropia yezoensis (Rhodophyta) from among genetic transformants generated via insertional mutagenesis. We characterized the mutant phenotype and identified the genomic region containing the mutation. The mutant produced spores (archeospores, zygotospores, and conchospores) at every relevant stage of the life history. No evident differences were observed in the appearance of the released spores at any stage under light microscopy between the wild-type and mutant strains; however, the mutant exhibited a trend of reduced spore release compared with the wild-type. Additionally, the archeospores released by the mutant remained round after being released from the sporangium, failed to adhere to the substratum, did not germinate, and showed no cell wall development after 4 days of standard culture, in contrast to the wild-type. Similar results were observed for the zygotospores and conchospores. These findings indicate that the main characteristic of this mutant was poor spore release, and the released spores failed to germinate. Whole-genome sequencing revealed the introduction of exogenous DNA into the nuclear genome of the mutant and suggested the presence of duplications, deletion, and inversion in the mutant genome. Notably, a deletion of approximately 13 kb was detected in the mutant genome flanking the insertion, and this region contained a plant homeodomain, suggesting that homeodomain-containing proteins may regulate spore development in P. yezoensis.
Strong genetic differentiation and low genetic diversity in a habitat-forming fucoid seaweed (Cystophora racemosa) across 850 km of its range.
Edgeloe JM, Starko S, Pessarrodona A … +4 more , Coleman MA, Batley J, Wernberg T, Wood GV
J Phycol · 2025 Jun · PMID 40318169 · Full text
Temperate seaweed forests are among the most productive and widespread habitats in coastal waters. However, they are under threat from climate change and other anthropogenic stressors. To effectively conserve and manage...
Temperate seaweed forests are among the most productive and widespread habitats in coastal waters. However, they are under threat from climate change and other anthropogenic stressors. To effectively conserve and manage these ecosystems under these rising pressures, an understanding of the genetic diversity and structure of habitat-forming seaweeds will be necessary. Australia's Great Southern Reef, a global hotspot of endemic diversity, is home to one of the world's most speciose habitat-forming seaweed genera, Cystophora (order Fucales). Despite severe declines in some species, genomic data on this genus remain limited. We used a reduced representation genomic approach (DaRTSeq) to investigate the genetic diversity and structure of Cystophora racemosa, a dominant canopy-forming species, across ~850 km of its range. Our sequencing captured 4741 high-quality single nucleotide polymorphisms (SNPs), and we distinguished neutral loci from those under natural selection (i.e., outlier loci). We identified strong population structure and high genetic differentiation for both neutral (mean F = 0.404) and outlier loci (mean F = 0.901). Across populations, genetic diversity was low (neutral: mean H = 0.046; outlier: H = 0.042), with high inferred inbreeding (neutral loci mean F = 0.531) and no evidence of isolation-by-distance. Several SNPs (n = 70) were observed to be putatively adaptive, with most (97%) correlated with annual maximum sea surface temperature (SST, °C), indicating local adaptation to this key ocean variable. Our results show that C. racemosa populations have low genetic diversity and high differentiation, both of which may increase the vulnerability of this important foundation species to global change.
What is Fragilaria koensabbei and does it matter what it is called? (Meta)barcoding and the science of taxonomy.
Williams DM
J Phycol · 2025 Jun · PMID 40318160 · Full text
Commentary is provided on the use of barcoding and metabarcoding in diatom studies and its broader relevance to the principles of taxonomy. The claims that taxonomy, however it is performed, is time-consuming and that it...
Commentary is provided on the use of barcoding and metabarcoding in diatom studies and its broader relevance to the principles of taxonomy. The claims that taxonomy, however it is performed, is time-consuming and that it requires extensive expertise, due to a constantly evolving taxonomy, are questioned as good, even useful, criteria by which to judge a science.
Intraspecific diversity in Raphidiopsis raciborskii: A key to its invasive success.
Willis A
J Phycol · 2025 Apr · PMID 40308159 · Publisher ↗
Abstract loading — click title to view on PubMed.
Restoring coastal resilience: The role of macroalgal forests in oxygen production and pH regulation.
Carlot J
J Phycol · 2025 Apr · PMID 40308156 · Publisher ↗
Abstract loading — click title to view on PubMed.
The role of microbiota in kelp gametophyte development and resilience to thermal stress.
Veenhof RJ, McGrath AH, Champion C … +3 more , Dworjanyn SA, Marzinelli EM, Coleman MA
J Phycol · 2025 Jun · PMID 40299544 · Full text
Ocean warming is driving profound changes in the ecology of marine habitat formers such as kelps, with negative implications for the biodiversity and ecosystem services they support. Thermal stress can disturb associated...
Ocean warming is driving profound changes in the ecology of marine habitat formers such as kelps, with negative implications for the biodiversity and ecosystem services they support. Thermal stress can disturb associated microbiota that are essential to the healthy functioning of kelp, but little is known about how this process influences early-life stages. Because kelps have a biphasic life cycle, thermal stress dynamics of adult sporophyte microbiota may not reflect those of the free-living haploid gametophyte. We investigated the role of microbial disruption under thermal stress on gametophytes of the kelp Ecklonia radiata and compared sporophyte and gametophyte microbiota. The microbiota of gametophytes changed significantly when the microbiome was disrupted and under increased temperature (26°C), in which putative generalist bacterial taxa proliferated and bacterial families associated with nitrogen fixation decreased. Concurrently, the survival of gametophytes decreased to <10%, and surviving gametophytes did not become fertile when the microbiome was disrupted. The length of gametophytes decreased under both microbial disruption and thermal stress. Taken together, this suggests that the associated microbiota of Ecklonia gametophytes is important for their survival, fertility, and response to warming. Gametophyte and parental sporophyte microbiota were also distinct from the water column but not each other, suggesting vertical transmission of microbiota from one life stage to the next. This study furthers our understanding of the role of microbiota in gametophyte stress tolerance as well as the acquisition of microbiota, which may prove vital in protecting and increasing the stress resilience of these foundation species.
Fluvioralfsia iberica gen. et sp. nov., Fluvioralfsiaceae fam. nov.: The first freshwater member of the Ralfsiales (Phaeophyceae), collected from streams in Spain.
Mellado-Díaz A, Moreno JL, Verdugo-Althöfer M … +2 more , Wehr JD, Saunders GW
J Phycol · 2025 Jun · PMID 40299519 · Publisher ↗
A novel brown alga inhabiting freshwater streams in Spain is described herein as Fluvioralfsia iberica gen. et sp. nov. Phylogenetic analyses establish it as a novel lineage within the Ralfsiales, Fluvioralfsiaceae fam....
A novel brown alga inhabiting freshwater streams in Spain is described herein as Fluvioralfsia iberica gen. et sp. nov. Phylogenetic analyses establish it as a novel lineage within the Ralfsiales, Fluvioralfsiaceae fam. nov. It is an epilithic crust, typically orbicular with a radial growth pattern, formed by dichotomous fan-like branching of filaments. Crusts show a bilateral symmetry with horizontal medial filaments that bend upward and downward to form circular or semilunar protrusions in concentric bands that overlap at different levels. Older crusts are easily seen with the naked eye, becoming greater than 50 cm in diameter and 1 cm thickness and can cover a high percentage of the stream bottom in optimal habitats. Differentiating characters from other families of Ralfsiales include the absence of phaeophycean hairs and plurangia and, most notably, the unangia originating intercalarily from lower cells of paraphyses. Most populations were located in first- to third-order calcareous streams and rivers, at altitudes of 14-870 m.a.s.l., in the mountainous Cantabrian coast, northern Spain, and one river in southeast Spain. Sites were entirely nonmarine, 2-118 km from the sea, with median conductance of 219 μS · cm (range 112-859) in well-oxygenated, oligo-mesotrophic waters and moderate to high current velocities. As freshwater brown algae are a species-poor group, Fluvioralfsia iberica represents an important addition to the global freshwater algal flora and raises additional questions about the origins of phaeophytes in fresh waters.
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