Journal Of Phycology[JOURNAL]
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200 papers
Bioluminescence of the heterotrophic dinoflagellate Polykrikos kofoidii Chatton 1914 (Dinophyceae).
Latz MI, Deheyn DD, Sprecher BN
J Phycol · 2026 Apr · PMID 41914493 · Full text
Heterotrophic dinoflagellates are important predators of phytoplankton, and many species produce bioluminescence, which is thought to serve as an antipredator function. The present study investigated the bioluminescence...
Heterotrophic dinoflagellates are important predators of phytoplankton, and many species produce bioluminescence, which is thought to serve as an antipredator function. The present study investigated the bioluminescence of the heterotrophic dinoflagellate Polykrikos kofoidii, an important predator of toxic and bloom-forming dinoflagellates. Its flashes were slow and dim compared to those of other dinoflagellates but with a similar spectral emission. Based on hyperspectral and laser confocal microscopy, autofluorescence consistent with that of luciferin was distributed throughout the cell, with only a few punctate sources typical of scintillons from other luminescent dinoflagellates. Polykrikos kofoidii consumed whole prey, which initially remained intact with measurable autofluorescence of chlorophyll, if plastid-containing, and luciferin, if luminescent. Polykrikos kofoidii encoded a luciferase gene with three conserved catalytic domains with an N-terminal region that appeared to contain a luciferin-binding protein-like motif. In three of the nine publicly available P. kofoidii transcriptomes, a luciferin-binding protein with homology to Noctiluca scintillans hybrid luciferase-luciferin binding domain was detected. The slow and dim flashes of P. kofoidii resulted in a bioluminescence signature that was distinct from other luminescent dinoflagellates, whereas the diffuse cellular distribution of luciferin fluorescence was unlike the punctate scintillon emission observed in previously studied luminescent dinoflagellates. This suggests that the cellular regulation of luciferin in P. kofoidii may differ from that of other dinoflagellates.
Increased prey choice is associated with higher kleptoplastidic reliance in Mesodinium ciliates.
L'Etoile-Goga A, Moeller HV
J Phycol · 2026 Apr · PMID 41914476 · Full text
Kleptoplastidic organisms display varying levels of reliance on stolen plastids, with some lineages evolving complex strategies for plastid (and other organelle) integration into metabolism. More complex methods of plast...
Kleptoplastidic organisms display varying levels of reliance on stolen plastids, with some lineages evolving complex strategies for plastid (and other organelle) integration into metabolism. More complex methods of plastid integration typically coincide with greater prey specialization, but it remains unclear whether or how kleptoplastidic lineages preferentially obtain organelles from compatible prey types. Here, we used the Mesodinium genus of ciliates, which span a gradient of reliance on kleptoplasty, to test for prey specialization during ingestion. We used two Mesodinum species: a highly kleptoplastidic species, M. rubrum, and a more mixotrophic species, M. chamaeleon. We conducted a series of experiments offering Mesodinium two different cryptophyte prey species simultaneously. Mesodinium and cryptophyte prey populations were measured across six different prey combinations. We observed that M. rubrum showed greater prey selectivity than M. chamaeleon at the time of ingestion. Despite this greater selectivity, M. rubrum was still unable to completely select for compatible prey types during feeding. Growth of M. rubrum was not affected by prey type over the course of this study, while limited effects on the growth of M. chamaeleon were seen. Preferential feeding by M. rubrum suggests the presence of a prey identification system that is not present in M. chamaeleon, consistent with our hypothesis that prey selectivity increases with increased reliance on kleptoplasty.
Unveiling the phylogenetic position of the type species of the syndinean genus Amoebophrya and broad divergence of the A. ceratii complex.
Kim S, Yoo J, Coats DW
J Phycol · 2026 Apr · PMID 41910218 · Full text
The syndinean genus Amoebophrya comprises endoparasitic dinoflagellates that infect various marine protists. Since the description of the type species, A. sticholonchae, a parasite of the radiolarian Sticholonche zanclea...
The syndinean genus Amoebophrya comprises endoparasitic dinoflagellates that infect various marine protists. Since the description of the type species, A. sticholonchae, a parasite of the radiolarian Sticholonche zanclea, an additional six Amoebophrya species have been formally described. Over the past 2 decades, intensive high-throughput environmental sequencing has discovered widespread and extensive diversity of novel marine alveolate group II (MALV II), generally considered the Amoebophryidae. Of the large number of uncultured environmental sequences, only several clades of MALV II are associated with a few sequences representing the Amoebophrya ceratii complex (ACC) infecting free-living dinoflagellates. In this study, we examined developmental traits and molecular signatures of A. sticholonchae and nine members of the ACC infecting diverse dinoflagellates from Korean coastal waters. Molecular phylogeny inferred from 18S rRNA gene sequences revealed that A. sticholonchae clustered with radiolarian-associated sequences, forming a basal lineage to the ACC, which comprised eight distinct clades (ACC1-8). Developmental traits were phylogenetically structured. Of the eight clades, ACC1-4 infected host nuclei and lacked temporary polyploidy, except that cytoplasmic infection occurred in Karlodinium veneficum cells containing multiple parasites; ACC5 and ACC8 exhibited cytoplasmic infection with temporary polyploidy, except for Prorocentrum micans, showing a similar frequency of cytoplasmic and nuclear infections, and ACC6-7 showed nuclear infection accompanied by temporary polyploidy. In contrast, A. sticholonchae uniquely combined cytoplasmic infection with the absence of temporary polyploidy. Although complex, these results suggest that phylogenetic divergence of the ACC group is generally consistent with developmental stage-specific characteristics, which is potentially useful in future taxonomic classification of this diverse lineage.
Temporal stability and spatial patterns of genetic diversity in populations of the climate-vulnerable fucoid Scytothalia dorycarpa.
Edgeloe JM, Coleman MA, Wood GV … +4 more , Starko S, Nimbs MJ, Batley J, Wernberg T
J Phycol · 2026 Apr · PMID 41873649 · Full text
Climate change is driving the loss of genetic diversity, potentially limiting species' capacity to adapt to environmental change. Detecting changes in genetic diversity requires replicated temporal data, which is lacking...
Climate change is driving the loss of genetic diversity, potentially limiting species' capacity to adapt to environmental change. Detecting changes in genetic diversity requires replicated temporal data, which is lacking for most species. Here, we combined contemporary and historical specimens of the climate-vulnerable fucoid Scytothalia dorycarpa to assess genetic diversity across ~2700 km of its geographic range. We analyzed four conserved organellar markers (rbcL, CO1, cox3, and trnW-1) using newly collected specimens and herbarium material to reconstruct past diversity. Scytothalia dorycarpa is endemic to Australia and has experienced climate-mediated declines over recent decades. We found stability in haplotype diversity over the 16-year sampling period, as well as across additional historical herbarium collections (1800s, 1883, 1960). We identified several common contemporary and historical haplotypes across the sampled range, but diversity patterns varied between markers. Nonetheless, consistent trends emerged for certain populations, with high, unique haplotype diversity consistently present across all markers and timepoints in the Cape Naturaliste-Leeuwin region (Western Australia). Notably, both contemporary and historical (now extinct) warm-edge populations had unique haplotypes that were absent elsewhere in the sampled range. These results demonstrate strong temporal stability in S. dorycarpa genetic diversity, with limited haplotype turnover, highlighting the resilience of sampled populations. The presence of unique haplotypes in specific populations underscores their role as reservoirs of evolutionary potential. By documenting long-term stability alongside localized diversity losses, this study provides a critical baseline for understanding the processes shaping genetic variation in S. dorycarpa and predicting its responses to future climate change.
Adapting the growth-form concept to geniculate coralline algae (Corallinales, Rhodophyta).
Schwoerbel J, Brodie J, Calderon MS … +16 more , Diaz-Pulido G, Gabrielson PW, Kato A, Le Gall L, Maneveldt GW, Maridakis C, Martone PT, Moro I, Mrowicki RJ, Nelson WA, Peña V, Rindi F, Rousseau F, Schils T, Tâmega FTS, Trentin R
J Phycol · 2026 Apr · PMID 41860761 · Full text
Geniculate coralline algae (Corallinales, Rhodophyta) are a diverse group of calcifying macroalgae, loosely united by flexible upright axes formed by alternating calcified (intergenicula) and uncalcified segments (genicu...
Geniculate coralline algae (Corallinales, Rhodophyta) are a diverse group of calcifying macroalgae, loosely united by flexible upright axes formed by alternating calcified (intergenicula) and uncalcified segments (genicula), a trait that has independently arisen several times. To standardize terminology, the concept of growth forms (i.e., the external gross morphology of a specimen) was developed previously for non-geniculate (without joints) corallines, but no such efforts have been undertaken for geniculate corallines. Here, we adapted the growth--form concept to geniculate corallines. We propose that, based on their branching pattern and two- or three-dimensional branch arrangement, geniculate corallines can be grouped into seven growth forms: unbranched (unbranched uprights), feather-like (complanate, pinnate branching), fan-like (complanate, dichotomous branching), irregular (complanate or multiplanar without a clear branching pattern), whorled (multiplanar, verticillate branching), arbuscular (multiplanar, dichotomous branching), and plumose (multiplanar, pinnate branching). We have provided a dichotomous key to assign specimens to different growth forms and discussed examples of each of these growth forms as well as the concept of intergrades between them. Additionally, we have provided a glossary of terms used in the growthform definitions and for intergenicular morphology. These tools will be a helpful resource for ecologists, taxonomists, beachcombers, and anyone interested in these comparatively little-studied but diverse macroalgae.
DNA sequencing of type material of Polyopes constrictus and Dermocorynus occidentalis (Halymeniales, Rhodophyta) supports Polyopes capensis sp. nov. and Polyopes occidentalis (Hollenberg) comb. nov.
Hughey JR, Leliaert F, De Clerck O … +1 more , Gabrielson PW
J Phycol · 2026 Apr · PMID 41860760 · Publisher ↗
Characterized by its expansive crust, short upright blades, and reproductive structures characteristic of Halymeniaceae, the northeast Pacific species Dermocorynus occidentalis was originally classified in that genus wit...
Characterized by its expansive crust, short upright blades, and reproductive structures characteristic of Halymeniaceae, the northeast Pacific species Dermocorynus occidentalis was originally classified in that genus with the morphologically similar generitype, D. montagnei. To determine if the generic placement of D. occidentalis was correct, four short rbcL gene amplicons from one of two syntype specimens of D. occidentalis, Hollenberg #650, were sequenced yielding 722 base pairs. The sequenced specimen is herein designated as the lectotype of D. occidentalis. A phylogenetic analysis of this and other rbcL gene sequences of selected Halymeniales, which included the generitype species of Dermocorynus, D. montagnei, fully resolved D. occidentalis in a clade with nine Polyopes spp. This clade included a complete rbcL gene sequence obtained from one of the specimens on the lectotype sheet of Fucus constrictus, the basionym of P. constrictus, the generitype of Polyopes from Australia. We also present the complete mitochondrial and plastid genomes obtained from the P. constrictus lectotype. These results support the transfer of D. occidentalis to Polyopes as P. occidentalis (Hollenberg) comb. nov. In addition, specimens identified as P. constrictus from South Africa were resolved in a clade well separated from the Australian P. constrictus. Consequently, we describe the South African specimens as Polyopes capensis sp. nov.
A clonal legacy? Reproductive mode variation in hard- and soft-bottom Gracilaria vermiculophylla populations.
Oetterer AP, Stoeckel S, Ryan WH … +1 more , Krueger-Hadfield SA
J Phycol · 2026 Apr · PMID 41852119 · Full text
The invasion of the red macroalga Gracilaria vermiculophylla provided an opportunity to investigate the influence of benthic habitats on the reproductive mode, population structure, and colonization dynamics in haploid-d...
The invasion of the red macroalga Gracilaria vermiculophylla provided an opportunity to investigate the influence of benthic habitats on the reproductive mode, population structure, and colonization dynamics in haploid-diploid life cycles. In hard-bottom habitats, we observed gametophytes and tetrasporophytes fixed by holdfasts to hard substrata, whereas in soft-bottom habitats, we observed free-living tetrasporophytes either drifting or anchored by tube-building polychaetes. We collected thalli from hard- and soft-bottom habitats along the Eastern Shore of Virginia and Maryland to investigate the role of substrate on life cycle and reproductive mode dynamics. We determined the phase and sex using observable reproductive structures and a sex-linked polymerase chain reaction (PCR) assay, followed by genotyping all thalli using nine microsatellite loci. Sexual reproduction prevailed in hard-bottom sites, whereas clonal (asexual) reproduction dominated soft-bottom sites, also accompanied by tetrasporophytic dominance. There was site-specific variation in selfing and clonal rates that were supported by observations of physiological stress and local extirpation, such as at Ape Hole Creek and Fowling Point, respectively. We observed evidence of isolation by distance and the structuring of genetic diversity by habitat type, then by site, and, finally, by year. Although broad patterns have been described across the extant range, we clarified population genetic patterns in hard- versus soft-bottom habitats with patterns not confounded by the invasion history comparing native and non-native thalli. These results have implications for the ongoing spread of this alga and contribute to our understanding of the population genetics of partially clonal taxa.
Host, substrate, and vertical position variations in microalgal communities on mangrove pneumatophores.
Lai KK, Li F, Tam NF … +6 more , Chen L, Xu SJ, Zhou H, Lam KL, Wong ES, Lee FW
J Phycol · 2026 Apr · PMID 41852080 · Publisher ↗
Mangrove pneumatophores provide unique habitats for algal assemblages, but previous research has mainly focused on macroalgae rather than microalgae. The variations among plant species and substrates on pneumatophores ha...
Mangrove pneumatophores provide unique habitats for algal assemblages, but previous research has mainly focused on macroalgae rather than microalgae. The variations among plant species and substrates on pneumatophores have also seldom been studied. The present study aimed to compare epiphytic microalgal communities on two substrates (adhered soil and pneumatophore itself) and two vertical segments (upper and lower) of pneumatophores in three mangrove species. Epiphytic microalgae varied between substrates and segments, with higher abundances in adhered soil than on pneumatophore itself and higher species richness on the lower than on the upper segment along a pneumatophore. The distribution of microalgal species differed between segments, with Ankistrodesmus spiralis exclusively observed on the upper segment of pneumatophore itself, although Oscillatoria was generally the most abundant genus in all microhabitats. On both substrates and segments, the diversity of microalgae in Sonneratia caseolaris was higher than that in Avicennia marina and S. apetala, with enriched Nitzschia sigma in S. caseolaris but Hydrosera sp. in A. marina. Water content and salinity were the most critical physicochemical factors affecting the overall microalgal community in adhered soil and on pneumatophore itself, respectively. An increase in salinity in adhered soil enhanced microalgal diversity and favored the growth of Nitzschia in both substrates. These results reveal that pneumatophores provide diverse microhabitats for epiphytic microalgae to colonize, with significant variations in compositions between substrates, vertical positions, and mangrove plant species, whereas the key environmental factors shaping the microalgal community were substrate specific.
Population and herbarium genomics provide a comprehensive framework for a revision of Microcoleus (Cyanobacteria).
Skoupý S, Stanojković A, Johansen JR … +5 more , Casamatta DA, McGovern C, Jungblut AD, Fastner J, Dvořák P
J Phycol · 2026 Apr · PMID 41848198 · Full text
Microcoleus is a cosmopolitan, filamentous cyanobacterium and a key component of biological soil crusts-complex microbial communities essential for primary production in diverse terrestrial environments. Here, we perform...
Microcoleus is a cosmopolitan, filamentous cyanobacterium and a key component of biological soil crusts-complex microbial communities essential for primary production in diverse terrestrial environments. Here, we performed a taxonomic revision of several species of Microcoleus based on a large population genomic dataset. The dataset was based on a Microcoleus speciation continuum characterized by variable levels of gene flow between the species. The putative species ranged from cryptic to distinctly morphologically defined lineages. We identify the type herbarium specimen and obtained a genome for the type species M. vaginatus and herein describe 10 novel species of Microcoleus. We provide epitypifications for the previously described species M. vaginatus and M. attenuatus. This research contributes to a more comprehensive understanding of terrestrial cyanobacterial biodiversity and cryptic species in cyanobacteria. It highlights the need for an extensive genomic and phenotypic dataset in the taxonomy of Cyanobacteria.
Influence of prey concentration, light intensity, and temperature on the growth and ingestion of the mixotrophic dinoflagellate Pyrophacus horologium, a predator of the harmful species Heterocapsa niei.
Seong MJ, Yun KW, Son HS … +2 more , Lee SM, Kim MC
J Phycol · 2026 Apr · PMID 41837726 · Full text
Pyrophacus horologium belongs to the family Pyrocystaceae and was recently identified as a mixotrophic dinoflagellate capable of feeding on other dinoflagellates. In this study, the growth and feeding responses of P. hor...
Pyrophacus horologium belongs to the family Pyrocystaceae and was recently identified as a mixotrophic dinoflagellate capable of feeding on other dinoflagellates. In this study, the growth and feeding responses of P. horologium were investigated under various environmental conditions by providing Heterocapsa niei, its preferred prey. The mixotrophic growth rate was measured in a feed concentration range of approximately 350 to 35,000 cells · mL, reaching saturation at approximately 8343 cells · mL. In the temperature experiment conducted under mixotrophic conditions (10-35°C at 90 μmol photons · m · s), positive growth was observed between 15 and 32°C, with the maximum mixotrophic growth rate of 0.48 · day recorded at 30°C (at 90 μmol photons · m · s). In the light intensity experiment conducted under mixotrophic conditions (0-348 μmol photons · m · s at 30°C), positive growth was observed between 24 and 170 μmol photons · m · s, with the maximum mixotrophic growth rate of 0.38 · day at 120 μmol photons · m · s (at 30°C). The maximum ingestion rates observed were 30.2 cells · predator · day (at 28°C and 90 μmol photons · m · s) and 28.5 cells · predator · day (at 30°C and 120 μmol photons · m · s). The result indicate that growth rates were significantly affected by temperature and light intensity. Collectively, these results provide insights into the environmental adaptability of P. horologium and its potential ecological implications, enhancing our understanding of mixotrophic dinoflagellates that graze on the harmful species H. niei.
Polyketides and fatty acids: Decoding the polyketide and fatty acid synthases evolution in Amphidinium carterae (Dinophyceae).
Mendoza-Flores A, Galindo-Sánchez CE, Mejía-Ruíz P … +1 more , Sánchez-Saavedra MDP
J Phycol · 2026 Apr · PMID 41830311 · Publisher ↗
Amphidinium carterae is a harmful bloom-forming dinoflagellate, a key source of polyketide metabolites-such as amphidinolides, amphidinols and amphidinins-and a producer of fatty acids. The biosynthesis of these compound...
Amphidinium carterae is a harmful bloom-forming dinoflagellate, a key source of polyketide metabolites-such as amphidinolides, amphidinols and amphidinins-and a producer of fatty acids. The biosynthesis of these compounds is mediated by polyketide synthases (PKSs) and fatty acid synthases (FASs). This study aimed to identify PKS and FAS genes present in the transcriptome of A. carterae and to understand the biosynthesis of polyketides and fatty acids, as well as the evolution of these secondary metabolites. A total of 24 transcripts encoding single-domain KS and seven multi-domain PKS transcripts were identified, including one with three KS domains and another comprising nine modules, the largest PKS reported in dinoflagellates to date. Phylogenetic analyses revealed a distinct clade separating single-domain and multi-domain PKSs in dinoflagellates, all of which resembled a type I PKSs. The modular architecture observed in A. carterae was like other dinoflagellates, suggesting a conserved domain structure likely shaped by gene duplication events. Seven transcripts were related to FASs; each transcript encoded an individual type II FAS, with a subcellular localization in the plastid. Gene duplication events appear to be a critical factor in the evolution of dinoflagellate PKSs. Furthermore, the similarity in multi-domain PKS architecture across different dinoflagellate species indicates that polyketide biosynthesis shares a common evolutionary origin within this group.
Light stress regulates pigment concentrations, growth, and gene expression in hatchery-cultivated Kappaphycus alvarezii (Solieriaceae, Rhodophyta).
Tabonda-Nabor AM, Crisostomo BA, Armaos A … +4 more , Schweizer G, Lluisma AO, Roleda MY, Fahrenkrug SC
J Phycol · 2026 Apr · PMID 41830304 · Publisher ↗
Kappaphycus alvarezii is a commercially valuable red seaweed cultivated for biomass and phycocolloid production. Enhancing its productivity, stress tolerance, and phycocolloid yield requires genetic diversification and o...
Kappaphycus alvarezii is a commercially valuable red seaweed cultivated for biomass and phycocolloid production. Enhancing its productivity, stress tolerance, and phycocolloid yield requires genetic diversification and optimized cultivation techniques. This study investigated the effects of different light intensities on growth, pigment composition, and gene expression in wild K. alvarezii to inform hatchery cultivation strategies. Eight wild-type strains were clonally cultivated under low, medium (control), and high light conditions for 28 days. High light resulted in the highest daily growth rate (6.03% ± 1.86%), whereas phycoerythrin (PE) levels were significantly higher under low light conditions. Gene expression analysis revealed that high light upregulated antioxidant-related genes (e.g., carotenoid-associated genes) and genes involved in DNA synthesis and repair, while repressing photosynthesis-related genes, likely as a protective response against oxidative stress. Low light reduced the expression of light-harvesting-related genes and intensified the expression of polysaccharide-degradation genes, potentially compromising carrageenan biosynthesis. Notably, the lectin KAA protein was highly induced under low light, suggesting a potential protective role against mannose-dependent pathogens. These results highlight the acclimative mechanisms of K. alvarezii under light stress and provide insights into metabolic regulation and energy allocation. Understanding these responses can help inform seaweed farmers about optimal cultivation depth and light exposure to maximize growth and enhance carrageenan yield, thereby contributing to sustainable aquaculture practices. Furthermore, transcriptome profiling identified key genes associated with carrageenan biosynthesis; together with the identification of light-regulated processes, these results provide candidate molecular targets for future genotype-based improvement and cultivation strategies aimed at enhancing carrageenan production.
An updated classification of growth forms in non-geniculate coralline algae (Corallinophycidae, Rhodophyta).
Maneveldt GW, Brodie J, Calderon MS … +16 more , Diaz-Pulido G, Gabrielson PW, Kato A, Le Gall L, Maridakis C, Martone PT, Moro I, Mrowicki RJ, Nelson WA, Peña V, Rindi F, Rousseau F, Schils T, Schwoerbel J, Tâmega FTS, Trentin R
J Phycol · 2026 Apr · PMID 41817374 · Full text
The current challenge of defining growth forms in the non-geniculate coralline red algae was addressed. Since the 19th century, those who have worked on this large and globally distributed group of algae have tried to su...
The current challenge of defining growth forms in the non-geniculate coralline red algae was addressed. Since the 19th century, those who have worked on this large and globally distributed group of algae have tried to summarize and systematically describe their growth forms. This effort resulted in a plethora of terms, which could sometimes be confusing, overlapping, and difficult to apply in the field. We reviewed the past literature to provide a coherent key to the non-geniculate coralline growth forms, incorporating the latest observations. Our revision expands the 10 currently recognized growth forms (unconsolidated, encrusting, warty, lumpy, fruticose, discoid, layered, foliose, ribbon-like, and arborescent) by redefining some of them, by reintroducing the columnar growth form, and by adding two new growth forms-convoluted and imbricate-to include recently documented specimens. This updated and refined tool better encompasses the diverse external morphologies of non-geniculate corallines. The goal was to facilitate taxonomic descriptions and to support ecological studies of non-geniculate corallines given the extreme difficulty of identifying species using only external characters.
Phytoplankton community structure in a subtropical river revealed by DNA metabarcoding, with a focus on cell-cyst coupling of Unruhdinium spp. (Dinophyceae).
Zheng Q, Wu Y, Gu H
J Phycol · 2026 Apr · PMID 41817372 · Publisher ↗
The subtropical Jiulongjiang River serves as a crucial water supply, yet it has been plagued by frequent blooms of the dinoflagellate genus Unruhdinium. To investigate the diversity and spatiotemporal dynamics of Unruhdi...
The subtropical Jiulongjiang River serves as a crucial water supply, yet it has been plagued by frequent blooms of the dinoflagellate genus Unruhdinium. To investigate the diversity and spatiotemporal dynamics of Unruhdinium species, we conducted seasonal sampling in Xipi Reservoir and large-scale sampling across the Beixi Creek of Jiulongjiang River from 2020 to 2021. Our cyst germination experiments revealed the cyst-theca relationships of U. minimum and U. kevei, along with the identification of two undescribed species. Unruhdinium minimum resembles Peridiniopsis kulczynskii in terms of cell size and plate pattern and probably is a junior synonym. Utilizing DNA metabarcoding to target the large subunit ribosomal RNA gene (LSU rDNA D1-D2) in both water and sediment samples, we detected seven species of Unruhdinium, with U. minimum, U. kevei, and U. penardii var. robusta emerging as the most dominant. Notably, U. minimum exhibited a preference for warm waters, while U. penardii var. robusta thrived in colder conditions. In contrast, U. kevei was predominantly observed in the spring. The alleviation of eutrophication and elevated nitrogen/phosphorus ratios may account for the decline of Unruhdinium blooms in the Jiulongjiang River since 2011. Our results enhance the possibility of dinoflagellate dynamics in freshwater systems and inform future conservation efforts in the subtropical rivers.
Comparative analysis of canonical and noncanonical rhodopsins in Amphidinium carterae and Karlodinium veneficum.
Wira J, Judd M, Baldino A … +2 more , Bachvaroff T, Place AR
J Phycol · 2026 Apr · PMID 41795203 · Publisher ↗
Rhodopsins are ancient and versatile light-sensitive proteins, widely distributed across microbial life. In dinoflagellates, however, their diversity and function remain poorly understood, owing to the lineage's extreme...
Rhodopsins are ancient and versatile light-sensitive proteins, widely distributed across microbial life. In dinoflagellates, however, their diversity and function remain poorly understood, owing to the lineage's extreme genomic divergence. Here, we surveyed the rhodopsin complements of two dinoflagellates, Amphidinium carterae and Karlodinium veneficum, using iterative profile-based searches, structural modeling, and motif-guided annotation. From the two species, 18 and 10 putative rhodopsin sequences were identified, respectively, with highly conserved retinal binding residues and a pocket. Of these sequences, several belonged to canonical families, including a finding of a heliorhodopsin in dinoflagellates. However, the majority were highly divergent sequences bearing noncanonical motifs and extensive accessory domains. The predicted ion-pumping capacities for both species were divergent based on helix C functional motifs, with K. veneficum rhodopsins maintaining canonical ion-pumping capacity, whereas A. carterae rhodopsins showed no functional similarity with canonical ion pumps. These results suggest functional innovation beyond ion-pumping, potentially toward signaling or light-dependent enzymatic activity in these two species.
Correction to 'Assessment of rhodolith-forming species diversity in British Columbia uncovers novel cryptic diversity in the genera Boreolithothamnion and Rhodolithia gen. nov. (Florideophyceae, Rhodophyta) and the occurrence of hybrid rhodoliths'.
J Phycol · 2026 Jun · PMID 41792992 · Publisher ↗
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Novel means for producing better-performing infertile kelp could herald a sea change in breeding opportunities for global seaweed farming.
Lindell S
J Phycol · 2026 Feb · PMID 41782233 · Publisher ↗
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Contrasting patterns of population structure in two habitat-forming kelp species in southeastern Australia.
Ryder FJ, Pearman WS, Layton C … +4 more , Parvizi E, Johnson C, Bellgrove A, Fraser CI
J Phycol · 2026 Apr · PMID 41773508 · Full text
The distribution and connectivity of species around the globe are changing at a rapid pace. Increasing sea temperatures are a driving factor of changes in temperate macroalgal distributions. Southeast Australia is consid...
The distribution and connectivity of species around the globe are changing at a rapid pace. Increasing sea temperatures are a driving factor of changes in temperate macroalgal distributions. Southeast Australia is considered a global ocean-warming hotspot, where macroalgal populations are predicted to decline significantly by 2100. We used genotyping by sequencing and Lagrangian particle modeling to compare the genetic population structure and connectivity of two habitat-forming macroalgae, Macrocystis pyrifera and Durvillaea potatorum, in southeastern Australia. Both species showed regional population structures, although this was greatest in D. potatorum, as which populations showed greater dissimilarity than in M. pyrifera. Particle modeling suggested that self-recruitment and connectivity among populations were highest in northeast Tasmania for both species, with particles often stranding along the nearby coast. Intriguingly, the southernmost M. pyrifera population in Tasmania shared more recent ancestry with a mainland Australia population. Although uncommon, simulations indicated that it is possible for rafts of M. pyrifera from mainland Australia to reach far-southern Tasmania. Hindcast simulations indicated those rafts are likely to come from mainland Australia via the Zeehan Current and along the western Tasmanian coast; unsampled western Tasmanian populations might therefore also share close ancestry with western mainland populations. With genetically distinct populations and low connectivity among areas, southeastern Australian kelp populations are vulnerable to losses of genetic diversity. This study provides insights into contemporary population structure and connectivity processes in two kelp species that form important habitats for biodiversity and fisheries on the Great Southern Reef and which are both undergoing range contractions with rapid environmental change.
Narrow thermal range restricts fertilization and early growth in the habitat-forming seaweed Durvillaea potatorum (Phaeophyceae)-Implications for aquaculture and climate resilience.
Yap VHS, Visch W, Hurd CL … +1 more , Wright JT
J Phycol · 2026 Apr · PMID 41773502 · Full text
The southern bull kelp Durvillaea potatorum is a key habitat-forming macroalga in southeastern Australia and has been identified as a species of interest for sustainable seaweed aquaculture. However, the species is threa...
The southern bull kelp Durvillaea potatorum is a key habitat-forming macroalga in southeastern Australia and has been identified as a species of interest for sustainable seaweed aquaculture. However, the species is threatened by rising ocean temperatures and other anthropogenic factors. Assessing the thermal limits across different life stages of D. potatorum is therefore crucial for understanding its response to warming and optimizing future aquaculture practices. Using a full two-factorial design, we tested the effects of a wide range of temperatures (~3.5-30.0°C) and two light regimes (zero/low light: 0/~40, and high light: ~120 μmol photons · m · s) on the reproductive and early life stages of D. potatorum from Eaglehawk Neck, Tasmania. Gamete release, fertilization, and early growth after 15 min, 24 h, and 7 days, respectively, were assessed. Thermal performance curves revealed that fertilization was the most thermally sensitive stage, exhibiting the lowest thermal optimum (T = ~12.85°C), and narrowest thermal breadth (T = ~2.5°C) independent of light conditions. Temperature and light had little to no effects on egg and sperm release, whereas early germling growth exhibited thermal optima of 16.33 and 14.50°C under low and high light treatments, respectively. These results indicate that fertilization conditions need to be closely monitored during the hatchery phase of aquaculture. In addition, natural D. potatorum populations may become increasingly susceptible to ocean warming due to impaired fertilization, potentially leading to demographic shifts and range contractions toward cooler waters.
Cold comfort for change: Stream mats as biological indicators of ecosystem processes in the McMurdo Dry Valleys, Antarctica.
Kohler TJ, Hawes I, Howkins A … +3 more , Zeglin LH, Gooseff MN, McKnight DM
J Phycol · 2026 Apr · PMID 41761901 · Full text
Glacier-fed streams (GFSs) make ideal systems for studying climate-related changes. Some of the best-studied GFSs are found in the McMurdo Dry Valleys (MDVs) of Antarctica, one of the Earth's coldest and driest deserts....
Glacier-fed streams (GFSs) make ideal systems for studying climate-related changes. Some of the best-studied GFSs are found in the McMurdo Dry Valleys (MDVs) of Antarctica, one of the Earth's coldest and driest deserts. Despite their harsh and isolated nature, MDV GFSs represent an oasis of life in a landscape visually devoid of it, with biomass dominated by photosynthetic microorganisms (including chlorophytes, cyanobacteria, and diatoms) and manifesting as benthic "mats." Mats form the basis of MDV GFS ecosystems, drive biogeochemical cycles, and harbor high proportions of the regional biodiversity. Furthermore, the biomass and composition of these mats respond to environmental fluctuations, making them ideal bioindicators for ecological monitoring. In this review, we have (1) distinguished the three major photosynthetic mat types by their taxonomic structure, habitat use, and elemental composition; (2) demonstrated how mat type distribution, coverage, and biomass are dictated by a combination of geomorphology, suspended sediment loads, and hydrology, among other factors; (3) introduced MDV diatoms as model organisms for investigating mat community assembly; and (4) speculated on how the biomass, community structure, and functional process rates of different mat types will change in a warmer and more connected world. Synthesizing this information, we suggest future opportunities for research, with the most promising avenues centering upon questions, methodologies, and scales that would have been inconceivable for the Heroic Age explorers that discovered them, ranging from studies of gene expression to cataloging changes in mat abundance by satellite.
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