Journal Of Phycology[JOURNAL]
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200 papers
Morphological and molecular approach uncovers hidden cryptic diversity within Polysiphonia sertularioides species complex (Rhodomelaceae, Rhodophyta).
de Brito JOF, Verbruggen H, Cassano V … +1 more , Díaz-Tapia P
J Phycol · 2025 Dec · PMID 41137605 · Publisher ↗
The use of a combination of molecular and morphological data in biodiversity assessments is increasing the knowledge of turf-forming seaweeds, showing that cryptic diversity appears to be widespread. Polysiphonia sertula...
The use of a combination of molecular and morphological data in biodiversity assessments is increasing the knowledge of turf-forming seaweeds, showing that cryptic diversity appears to be widespread. Polysiphonia sertularioides is a turf-forming filamentous alga with a presumed global distribution based on morphological identifications. Published molecular data, however, suggest that it represents a species complex with at least four lineages. To investigate the extent of the P. sertularioides complex and species distribution, we analyzed molecular and morphological data from 75 specimens from Australia, Brazil, Europe, and South Africa. The rbcL gene sequences were used for phylogenetic inference and species delimitation using Generalized Mixed Yule Coalescent, Poisson Tree Processes, and Assemble Species by Automatic Partitioning methods. Our analyses revealed that the P. sertularioides complex comprises 14-21 species, with 10 of the species recovered in all analyses. The species were recovered in two main, highly supported clades, one composed of European (Mediterranean and Macaronesian) species and the other composed of species from Australia, Brazil, Europe, Panama, and South Africa. Statistical analyses of a morphometric dataset of nine characters revealed that the species represents a morphological continuum, and although species from different regions were distinct, species from a region were morphologically indistinguishable. Most of the recovered species were restricted to a biogeographical region, rarely spanning different continents, with 10 endemic species. Our results revealed a case of true cryptic diversity in the P. sertularioides complex, highlighting the need for studies of small-sized algae (<5 cm).
Identifying putative calcification and decalcification genes in the geniculate coralline alga, Calliarthron tuberculosum.
Jourdain E, Martone PT
J Phycol · 2025 Dec · PMID 41128363 · Full text
Coralline algae form highly calcified thalli, creating key substrate that promotes biodiversity in nearshore marine environments. Although calcification and decalcification are critical for coralline growth and ecologica...
Coralline algae form highly calcified thalli, creating key substrate that promotes biodiversity in nearshore marine environments. Although calcification and decalcification are critical for coralline growth and ecological function, their underlying mechanisms are not fully understood. We capitalized on the unique morphology of articulated coralline algae, assembling tissue-specific transcriptomes for calcified (intergenicular), uncalcified (genicular), and actively decalcifying (young genicular) tissues in the coralline alga Calliarthron tuberculosum and compared gene expression to identify putative calcification and decalcification genes. We captured the greatest differences in gene expression between calcified and uncalcified tissue, with 17.7% (5238 genes) of the genes in the transcriptome differentially expressed, the majority of which (10.9%) were upregulated in calcified tissue. There were also significant differences between decalcifying and uncalcified tissue, with 14.3% (4420 genes) of the genes in the transcriptome differentially expressed. We used functional gene annotation to identify 18 putative calcification genes and 10 putative decalcification genes. Results showed calcium-binding proteins, a vacuolar calcium transporter, and a calcium ATPase may be important for transporting calcium ions during calcification, whereas a proton ATPase may be important for maintaining pH homeostasis in calcified tissue. Additional genes for hydrogen ion transport were highly expressed in uncalcified tissues, including a sodium/hydrogen exchanger and hydrogen pump, which may be important for accumulating hydrogen ions to maintain uncalcified tissues. Differential expression of carbonic anhydrases and aquaporins indicated potential mechanisms for dissolved inorganic carbon transport in calcified and uncalcified tissues. This study has created valuable molecular resources for coralline algae and lent new insights on mechanistic details surrounding calcification and decalcification.
Globally coordinated research investigates the impacts of marine carbon dioxide removal on phytoplankton communities.
Ringham M
J Phycol · 2025 Oct · PMID 41127916 · Publisher ↗
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The hidden toxicity of Pseudanabaena: A notable leap in cyanobacterial research.
Pereira L
J Phycol · 2025 Oct · PMID 41127908 · Publisher ↗
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Introgression and intermixing in North Pacific Alaria.
Terpis KX, Lane CE
J Phycol · 2025 Oct · PMID 41127905 · Publisher ↗
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A taxonomic sudoku: Resolving the long-standing puzzle of Japanese Dictyoteae (Dictyotales, Phaeophyceae) with new records and biogeographic insights.
Vieira C, Akita S, Suzuki M … +5 more , Terada R, Hanyuda T, Shimada S, Uwai S, Kawai H
J Phycol · 2025 Oct · PMID 41070990 · Full text
Japanese Dictyoteae have been documented since 1838, with a historical checklist of 21 names recorded prior to 1990. Persistent misidentifications-particularly of species originally described from Europe and the Americas...
Japanese Dictyoteae have been documented since 1838, with a historical checklist of 21 names recorded prior to 1990. Persistent misidentifications-particularly of species originally described from Europe and the Americas-have complicated the taxonomy of the group in Japan. We reevaluated historical records and revised the national checklist for Canistrocarpus, Dictyota, Dilophus, and Rugulopteryx using integrated morpho-genetic analyses. Broad sampling from Hokkaido to Okinawa, including Japanese type localities, together with sequence data from type localities of species described elsewhere but reported in Japan, corrected persistent taxonomic ambiguities. The long-standing misapplication of the Asian D. dichotoma as D. spathulata was resolved. The revised checklist recognizes 19 species: 17 Dictyota, Canistrocarpus cervicornis, and Rugulopteryx okamurae. Species richness peaks in Kyushu with 15 species, whereas only D. spathulata extends to Hokkaido. Eight taxa appear native to the Northwest Pacific, including D. coriacea, D. haenyeosa, D. spathulata, D. spinulosa, D. sumbisoria, D. taewakia, Dictyota churaumia sp. nov., and R. okamurae. Twelve taxa exhibit broad, transoceanic distributions. We describe Dictyota churaumia sp. nov. and formally report nine species from Japan for the first time: Dictyota acutiloba, D. ceylanica, D. haenyeosa, D. humifusa, D. liturata, D. pfaffii, D. sandvicensis, D. sumbisoria, and D. taewakia. By integrating molecular data with morphological analyses, we resolved major taxonomic misidentifications and implemented the necessary taxonomic treatments (synonymies and typifications) to provide an updated taxonomic framework for the Dictyoteae flora of Japan. The presence of unique morphologies in historical herbarium specimens, coupled with unexplored regions of Japan, indicates a potential for additional, unidentified species.
A phylogenetic investigation of the genus Spyridia (Callithamniaceae, Rhodophyta) in Bermuda uncovers four new species.
Schneider CW, Saunders GW
J Phycol · 2025 Dec · PMID 41060305 · Publisher ↗
In a molecular-assisted alpha taxonomic study of the genus Spyridia in Bermuda, several new species were discovered in a complex previously recognized as the two species S. aculeata and S. filamentosa in the islands. Kno...
In a molecular-assisted alpha taxonomic study of the genus Spyridia in Bermuda, several new species were discovered in a complex previously recognized as the two species S. aculeata and S. filamentosa in the islands. Known in Bermuda since 1857, S. aculeata is genetically confirmed for all isolates bearing uncinate spines on their determinate branches, thus including all specimens that had in the past been identified as S. complanata and S. hypnoides. The most abundant species in the flora is S. consimilis sp. nov. found subtidally around the islands and historically thought to be S. filamentosa, a species with which it is morphologically cryptic. The other three new genetically distinct species are also non-uncinate: S. bernatowiczii, S. rhizoidea, and S. struanii. Spyridia bernatowiczii would have likely been also identified as S. filamentosa in the past and is genetically and morphologically distinct from S. consimilis. The remaining two species are smaller, forming cushions or tufts in intertidal and shallow subtidal habitats.
Phylogenetic relationships among seven freshwater red algal genera in the Batrachospermaceae (Batrachospermales, Rhodophyta) using complete chloroplast genome data.
Crowell RM, Karol KG, Vis ML
J Phycol · 2025 Dec · PMID 41051011 · Full text
Systematics studies within the freshwater red algal order Batrachospermales have used only one to a few genes to infer evolutionary relationships. The phylogenetic trees presented in these studies recovered monophyletic...
Systematics studies within the freshwater red algal order Batrachospermales have used only one to a few genes to infer evolutionary relationships. The phylogenetic trees presented in these studies recovered monophyletic genera with strong support, but the relationships among genera were often not well supported. Chloroplast genome sequencing may provide the necessary data to obtain a fully resolved, strongly supported phylogeny. In order to test the efficacy of this approach, we focused on a subclade of seven genera and sequenced chloroplast genomes from 10 species. Utilizing new and previously published data, a phylogeny was constructed from 132 chloroplast-encoded genes. The relationships among all seven genera had strong statistical support. The phylogeny and gross morphology of genera showed concordance. Lemanea and Paralemanea with tube-like pseudoparenchymatous gametophytes formed a clade, and five genera-Batrachospermum, Lympha, Sirodotia, Tuomeya, and Volatus-with beaded gametophytes formed a second clade. Within the clade of five genera, Batrachospermum with pedicellate carposporophytes was sister to the other three genera with axial carposporophytes and Sirodotia with prostrate carposporophytes along the axis. The results highlight the potential for chloroplast genome data to clarify evolutionary relationships in the Batrachospermales, offering a promising approach for future studies aimed at understanding the broader evolutionary history of this group.
Boreolithothamnion acuminatum sp. nov., B. homoglobosum sp. nov., B. jejuensis sp. nov., and B. japonium comb. nov. (Hapalidiales, Rhodophyta) from Korea: Expanding diversity and biogeographic range in the Northwest Pacific region.
Jeong SY, Won BY, Fredericq S … +1 more , Cho TO
J Phycol · 2025 Dec · PMID 41039959 · Full text
The non-geniculate coralline genus Boreolithothamnion currently includes eight species with a Northern Hemisphere distribution. To date, only a few studies have focused on the systematics of Boreolithothamnion species. H...
The non-geniculate coralline genus Boreolithothamnion currently includes eight species with a Northern Hemisphere distribution. To date, only a few studies have focused on the systematics of Boreolithothamnion species. Here, we performed morphological and phylogenetic analyses, based on rbcL, psbA, and SSU rRNA gene datasets, on Boreolithothamnion from Korea as well as DNA-sequenced type material representing nine names. The analyses supported the proposal of three new species of Boreolithothamnion from Korea: B. acuminatum sp. nov., B. homoglobosum sp. nov., and B. jejuensis sp. nov. Boreolithothamnion acuminatum is distinguished by its encrusting to warty growth form, acuminate to cylindrical protuberances, and raised to low-domed tetra/bisporangial conceptacles having bordered pore canals with three to four roof cells. Boreolithothamnion homoglobosum is characterized by a fruticose or unattached rhodolith and simple to bifurcated protuberances. Boreolithothamnion jejuensis is distinguished by an encrusting to undulate or knobby growth form with unbranched protuberances. Phylogenetic analysis of the holotype of Lithothamnion japonicum (TRH C16-3267) based on the psbA gene strongly supported its transfer to the genus Boreolithothamnion, B. japonicum comb. nov. Eight other type specimens of Lithothamnion were also observed to cluster within the Boreolithothamnion clade and were resolved with previously accepted species. This study expands the biogeographical range of Boreolithothamnion in the Northwest Pacific.
Species-environment relationships of coastal diatoms from the Sept-Îles region, Gulf of St-Lawrence (Québec, Canada).
Arseneault E, Saulnier-Talbot É
J Phycol · 2025 Dec · PMID 41020742 · Full text
As climate change is having increasingly visible impacts on coastal regions, it is urgent to better understand its effects on the state of ecosystems and the services they provide. To assess the direction and magnitude o...
As climate change is having increasingly visible impacts on coastal regions, it is urgent to better understand its effects on the state of ecosystems and the services they provide. To assess the direction and magnitude of change in the high-use waters of the Sept-Îles region in the Gulf of St-Lawrence, we sampled 35 sites along the coast and explored the relationship between surface diatom assemblages and 21 environmental variables. Temperature (14.62%), Secchi depth (12.97%), dissolved silica (6.91%), and magnesium (6.23%) were determined to be significant and independent variables explaining variation in diatom distribution, together explaining 28.6% of the assemblage variance. Temperature and Secchi depth met the λ/λ > 0.5 criterion, but only temperature was selected to develop a transfer function, as these two variables were strongly correlated. A diatom-based temperature transfer function was then developed using weighted-averaging partial least squares (WAPLS; 3; r = 0.59, RMSEP = 0.45°C), based on a training set of 32 sites and 55 benthic taxa. However, the model exhibited sensitivity to spatial autocorrelation and may have been influenced by secondary and unmeasured variables. Despite these limitations, the model provides valuable insight into the spatial variability of diatom assemblages and offers potential for paleoenvironmental reconstructions. For optimal inferences, the model should be applied within the studied area. This study contributes to understanding how coastal diatom assemblages respond to environmental gradients and highlights the importance of diatom-based monitoring to assess ongoing ecological changes in aquatic environments.
An undescribed species within the Gymnodinium sensu stricto group found responsible for an exceptional bloom in the Southern Ocean.
Mascioni M, Cusick A, Sanchez-Puerta MV … +5 more , Johnson C, Zheng H, Reynolds RA, Allen AE, Almandoz GO
J Phycol · 2025 Dec · PMID 41014142 · Publisher ↗
Naked dinoflagellates are a regular component of the Antarctic phytoplankton but remain poorly studied. In December 2016, the first massive bloom (9.5 × 10 cells · L) of small (~15 μm) naked dinoflagellates was recorded...
Naked dinoflagellates are a regular component of the Antarctic phytoplankton but remain poorly studied. In December 2016, the first massive bloom (9.5 × 10 cells · L) of small (~15 μm) naked dinoflagellates was recorded in the western Antarctic Peninsula. To identify these organisms, we performed Illumina next-generation sequencing analysis on field samples to obtain genetic information (SSU rDNA 18SV9 and 16SV4-V5). In addition, we performed polymerase chain reaction (PCR) amplification and Sanger sequencing using dinoflagellate-specific primers (LSU rDNA D1-D3 and ITS/5.8S), as well as traditional light and scanning electron microscopy observations. Phylogenetic analyses revealed that these organisms belonged to the Gymnodinium sensu stricto group and may represent an undescribed species. These analyses also indicated that the observed organisms were closely related to the species Gymnodinium dorsalisulcum, G. impudicum, Barrufeta bravensis, and B. resplendens, as well as to the genera Lepidodinium and Wangodinium. This work has provided the LSU rDNA gene sequence from an Antarctic species belonging to the Gymnodinium sensu stricto group along with a description of the observed morphology of these Antarctic blooming dinoflagellates. We compared the 18S V9 amplicon sequence variant (ASV) that dominated the bloom with global databases and observed that it is widely distributed in the Antarctic Peninsula as well as in the global ocean. This study highlights the need for further efforts to identify and describe the diversity of naked dinoflagellates in Antarctic waters.
Auxospore fine structure and development in the surirelloid diatom Campylodiscus cf. neofastuosus (Bacillariophyta).
Idei M, Mann DG, Watanabe T … +1 more , Sato S
J Phycol · 2025 Oct · PMID 41002163 · Publisher ↗
The development of the auxospore is reported in the surirelloid diatom Campylodiscus cf. neofastuosus. As in most pennate diatoms, growth of the auxospore is accompanied and constrained by the formation of a transverse p...
The development of the auxospore is reported in the surirelloid diatom Campylodiscus cf. neofastuosus. As in most pennate diatoms, growth of the auxospore is accompanied and constrained by the formation of a transverse perizonium composed of finely structured bands, which are added one after another as the auxospore expands. However, unlike in most pennate diatoms, in which the transverse perizonium develops bidirectionally from a hoop-like or shortly cylindrical primary band formed around the equator of the zygote, in C. cf. neofastuosus, development is unidirectional, outward from a heart-shaped cap at one end of the auxospore. Limited evidence from other surirelloid diatoms suggests that unidirectional perizonium development may be typical of the group. This developmental pattern correlates with the profound symmetry shifts that have occurred during the evolution of the circumferential raphe system of Surirellaceae and may have a common origin with these, despite the difference in life-cycle stage. The longitudinal perizonium of Campylodiscus also exhibits differences from the arrangement typical of most raphid diatoms, since it comprises three concentrically organized bands, including a unique, heavily silicified secondary band, which runs around the whole circumference of the wide primary band. In this and some other Surirellaceae, the longitudinal perizonium seems to play an important role in the morphogenesis of the initial cells by controlling the shape of the protoplast during a contraction before the formation of the initial epivalve. Small extra perizonial elements, unlike any reported previously in raphid diatoms, were detected beneath the suture formed by the ends of the transverse perizonial bands.
Influence of trace metal additions on the longevity of algal blooms across a productivity gradient.
Gladfelter MF, Bela IG, Wilson AE
J Phycol · 2025 Dec · PMID 40994305 · Full text
Phytoplankton require specific nutrients in varying quantities for growth, defense, and proper cell functioning. When macronutrients are present in excess, trace metals can exhibit co-limitation on phytoplankton. This ex...
Phytoplankton require specific nutrients in varying quantities for growth, defense, and proper cell functioning. When macronutrients are present in excess, trace metals can exhibit co-limitation on phytoplankton. This experiment aimed to understand how ambient nutrient concentrations impact phytoplankton community persistence (i.e., bloom longevity). To examine potential interactions, three ponds of escalating trophic states were selected. Pond water was transferred into sealed, clear, floating plastic containers inside a floating frame within each pond. The containers were treated with a full factorial design of additions of nitrogen, phosphorus, and/or a mixture of trace metals. In the oligotrophic pond, the containers treated with nitrogen, phosphorus, and trace metals had 39% more phytoplankton than those treated with just nitrogen and phosphorus, by the end of the experiment. In the mesotrophic pond, the containers treated with nitrogen and trace elements had 14% more phytoplankton than those with nitrogen alone, by the conclusion of the experiment. In the eutrophic pond, no combinations of added nutrients affected algal growth when compared to the control treatment. These results show that the addition of trace metals along with nitrogen and phosphorus allowed phytoplankton to resist the effects of nutrient starvation when compared with treatments that only provided nitrogen and phosphorus. These results indicate the utility of trace metals for sustaining rather than limiting algal growth.
Systematics and taxonomy of Codium (Bryopsidales, Chlorophyta) in the Hawaiian Islands: Description of six new species.
Sherwood AR, Allsopp KR, Alvarado EA … +5 more , Kosaki RK, Paiano MO, Rentsch P, Spalding HL, Wade RM
J Phycol · 2025 Dec · PMID 40994301 · Publisher ↗
The well-known Bryopsidalean genus Codium has a worldwide distribution and contains almost 150 species, with cryptic diversity confusing the actual number. In the Hawaiian Islands, 15 species have been previously recorde...
The well-known Bryopsidalean genus Codium has a worldwide distribution and contains almost 150 species, with cryptic diversity confusing the actual number. In the Hawaiian Islands, 15 species have been previously recorded, with several of these described in the past several decades, largely from specimens collected from mesophotic coral ecosystems. We assessed the diversity of Codium in Hawai'i from both shallow and mesophotic habitats by employing DNA barcoding and phylogenetic analyses of partial rbcL and tufA gen plastid markers and morphological characterization. DNA sequence analyses supported 18 species of Hawaiian Codium (eight of which are considered endemic), which is a 20% increase in recognized species richness for this genus in Hawai'i. Ten previously reported species were confirmed or provisionally confirmed, six new species have been described (C. pikoii sp. nov., C. upohoae sp. nov., C. hakakaupilii sp. nov., C. kanepohihiae sp. nov., C. torulosum sp. nov., and C. iolekaae sp. nov.), and two new records have been reported (C. "geppiorium4" and C. taylorii). Twenty-eight percent of Hawaiian Codium clades were mesophotic only, and 22% were shallow only, while 50% of clades were known from both shallow and mesophotic depths. Recent emphasis on the systematics of Hawaiian mesophotic algae has sufficiently increased specimen numbers from this habitat to allow a more complete assessment of the genus in this location, making it one of the most thoroughly collected and studied marine algal genera from Hawai'i and an excellent model for future examination of both horizontal (i.e., spatial) and vertical (i.e., depth) distributional trends.
Short-term resilience, long-term costs: Reduced growth and increased erosion in the kelp Ecklonia radiata (phylum Ochrophyta) following repeated marine heatwaves.
Wynn OJ, Britton D, Beardall J … +5 more , Iha C, Nardelli A, Raven JA, Bridle A, Hurd CL
J Phycol · 2025 Oct · PMID 40994297 · Full text
Marine heatwaves (MHWs) have increased in frequency by 34% since 1990 and are projected to rise further with global ocean change, posing significant risks to marine ecosystems. Kelps (order Laminariales) provide essentia...
Marine heatwaves (MHWs) have increased in frequency by 34% since 1990 and are projected to rise further with global ocean change, posing significant risks to marine ecosystems. Kelps (order Laminariales) provide essential habitats and play key ecological roles, but they are increasingly threatened by MHWs. Tasmania, SE Australia, is a global warming hotspot, but the impacts of recurrent MHWs on the physiological performance of the ecologically dominant kelp Ecklonia radiata remain poorly understood. To address this, we investigated how the frequency of MHWs influenced the physiological and biochemical performance of E. radiata, both during and after MHWs, to evaluate immediate responses and recovery potential. In laboratory experiments, juvenile sporophytes were exposed to three experimental treatments: no-MHW, a single 6-day MHW, and double 6-day MHWs followed by 7-day recovery periods. Ecklonia radiata sporophytes were resilient to the single 6-day MHW, but double MHWs negatively impacted recovery, with reduced growth rates and increased tissue erosion. Although photosynthetic rates remained unaffected, changes in pigment ratios and increased antioxidant activity indicated a mitigation of physiological stress. We propose that energy may be diverted from growth toward repair processes and the maintenance of essential functions. These findings suggest there was cumulative stress caused by repeated MHWs, leading to progressive physiological decline. More frequent MHW events may hinder E. radiata's recovery capacity, with potential ecosystem implications, considering its key ecological role.
Bull kelp (Durvillaea amatheiae) in southeastern Australia has compromised adaptive capacity to future ocean warming.
Nimbs MJ, Davis TR, Coleman MA
J Phycol · 2025 Oct · PMID 40990839 · Full text
Temperate Australian kelp forests are highly vulnerable to range contractions because of ongoing ocean warming and extremes. The current mainland distribution of the bull kelp Durvillaea amatheiae is confined to the far...
Temperate Australian kelp forests are highly vulnerable to range contractions because of ongoing ocean warming and extremes. The current mainland distribution of the bull kelp Durvillaea amatheiae is confined to the far southeastern corner of the continent where warming is occurring two to four times faster than the global average. Extant populations will, thus, require sufficient genetic adaptive capacity to survive these extremes. We examined neutral and adaptive genomic diversity to assess the adaptive capacity and selective pressure on these range edge populations. We have revealed that prevailing ocean currents and dispersal-restrictive life-history traits have resulted in isolated, inbred populations across the southeastern range, particularly at the northern edge. Temperature-related candidate loci exhibited signatures of selection along thermal gradients, with many of these alleles fixed across the species range, suggesting little remaining adaptive capacity, particularly among the warmest populations. Combined, these elements suggest D. amatheiae may be susceptible to range contractions in the face of ongoing climate change.
Polyculture of marine algae: Best combination for biomass, biochemical, and biodiesel properties.
Vahdat S, Noori F, Van Stappen G … +1 more , Agh N
J Phycol · 2025 Oct · PMID 40981282 · Publisher ↗
Overyielding in polyculture systems suggests a potential for greater productivity than that observed in monocultures. Optimized algal polyculture combinations can significantly enhance biomass production and yield valuab...
Overyielding in polyculture systems suggests a potential for greater productivity than that observed in monocultures. Optimized algal polyculture combinations can significantly enhance biomass production and yield valuable biochemicals. The study tested seven different treatments of Nannochloropsis oculata, Chlorella sp., and Dunaliella tertiolecta in different ratios T1: (1:1:1), T2: (1:1:2), T3: (1:2:1), T4: (2:1:1), T5: (1:2:2), T6: (2:2:1), and T7: (2:1:2), respectively, under different photoperiods to assess the best combination for biomass, biochemical, and biodiesel properties. The results showed that under a 12:12 h light:dark photoperiod, T7 had the highest lipid and protein contents. There were also higher degrees of unsaturation in treatments 3, 6, and 7, whereas treatments 1, 2, and 4 had higher values for low carbon fuel standard and cold filter plugging point. Under a 16:8 h photoperiod, T3 had the highest total number of cells, T1 had the highest lipid level, and T3 had the highest protein level. Treatments 2 and 3 had significantly higher iodine values than the others, whereas T3 and T6 had higher cetane numbers. The results indicate that the highest protein and lipid levels were obtained in T3 under a 16:8 h photoperiod, whereas T1 had its highest protein and lipid levels during a 12:12 h photoperiod. Additionally, the highest biomass and mono-unsaturated fatty acids were observed in T3 under a 16:8 h photoperiod, and there were no significant differences in saponification values between treatments. Based on these findings, we recommend conducting algal polyculture with T3 (1:2:1) under a 16:8 h light:dark photoperiod to achieve optimal biomass production, higher protein, lipid, and mono-unsaturated fatty acid levels.
The effects of iron limitation on the small chlorophyte Micromonas from the Northeast Pacific Ocean.
Meyer MG, White VJ, Torano O … +3 more , Hannoush H, Lankford M, Marchetti A
J Phycol · 2025 Oct · PMID 40938256 · Publisher ↗
Small eukaryotic phytoplankton can account for a considerable amount of biomass and primary production in high nutrient, low chlorophyll (HNLC) regions of the ocean where iron limitation is pronounced. However, the physi...
Small eukaryotic phytoplankton can account for a considerable amount of biomass and primary production in high nutrient, low chlorophyll (HNLC) regions of the ocean where iron limitation is pronounced. However, the physiological and metabolic strategies these cells invoke to cope under low iron conditions and the extent to which they are responsible for new production (i.e., the fraction of primary production supported by nutrients from outside of the euphotic zone) are unclear. Here, we examined how a representative picoeukaryote-the chlorophyte Micromonas sp., recently isolated from the iron-limited subarctic Northeast Pacific Ocean-responded to iron limitation when grown on nitrate as a nitrogen source. Iron-limited Micromonas exhibited reductions in growth rate, cell volume, and elemental quotas along with a restructuring of cellular metabolism. Gene expression and metabolic pathway analyses showed evidence of strategies to mitigate iron limitation with constitutive expression of genes related to nitrogen uptake and utilization. Additionally, cellular carbon and nitrogen quotas were 20-70 fmol C · cell and 3.3-20 fmol N · cell, respectively, as a function of iron status. Based on the measured cellular quotas, we have estimated that representative picoeukaryotes (<2 μm), such as Micromonas, in HNLC Northeast Pacific waters can account for a significant proportion of new production, supporting the need for a reconsideration of the role small eukaryotic phytoplankton play in the global carbon cycle.
Four novel taxa of cyanobacteria from a unique thermal cave habitat in Vromoner Canyon, Albania.
Pokorný J, Vondrášková A, Wipplingerová M … +1 more , Kaštovský J
J Phycol · 2025 Oct · PMID 40937890 · Full text
Thermal and cave habitats on nearly all continents have been a substantial source of new cyanobacterial genotypes and morphotypes that expanded with the dawn of the era of molecular phylogenetics. In this study, we inves...
Thermal and cave habitats on nearly all continents have been a substantial source of new cyanobacterial genotypes and morphotypes that expanded with the dawn of the era of molecular phylogenetics. In this study, we investigated the cyanobacterial flora of an extreme habitat of recently discovered caves with sulfur-rich thermal springs, using the polyphasic approach. The methods included cultivation, light and transmission electron microscopy, and molecular methods, including those that can be employed on samples that are not unialgal. Here, we present data on morphological and ultrastructural characteristics, 16S rRNA gene and 16S-23S internal transcribed spacer (ITS) rRNA region sequences, and folding structures. We identified one new trichal genus Xomosiella with the type species X. audyi forming a distinctly isolated clade and three new species in Loriellopsis, Mastigocladus, and Pegethrix. Apart from genetic distance, Xomosiella is distinguished from Limnothrix by its high trichome motility and benthic habitat, with granules likely composed of cyanophycin rather than aerotopes. The coccal cyanobacterium initially identified as "Cyanosarcina" sp. has been proposed as a new species, Loriellopsis vromonerensis, although its classification is complicated by morphological plasticity and phylogenetic uncertainties. The erection of Mastigocladus boudae was supported by a significant genetic divergence and distinct morphological characteristics. A description of a newly revealed cryptic species, Pegethrix sulphurea, has been provided. These results advance our knowledge of the diversity of cyanobacteria in extreme and understudied environments, which could enrich our understanding of microbial adaptability.
Finding Euastropsis Lagerheim (Chlorophyceae): Insights into morphological and genome evolution in the green algal family Hydrodictyaceae.
McManus HA, Karol KG, Lenarczyk J
J Phycol · 2025 Oct · PMID 40906357 · Publisher ↗
Recent phylogenetic studies of the family Hydrodictyaceae (Sphaeropleales, Chlorophyceae) included all but one of the genera, Euastropsis, which was excluded due to a lack of living material. A 2017 discovery of E. richt...
Recent phylogenetic studies of the family Hydrodictyaceae (Sphaeropleales, Chlorophyceae) included all but one of the genera, Euastropsis, which was excluded due to a lack of living material. A 2017 discovery of E. richteri in Lake Kocie, Poland, provided an opportunity to study the morphology, ultrastructure, plastome architecture, and phylogenetic placement of this monotypic genus. The overall morphology fit the original description, being two-celled with some variations in size and number of daughter coenobia. The plastome (GenBank accession PQ469705) architecture and gene content of E. richteri are characteristic of Hydrodictyaceae. Phylogenetic analyses placed E. richteri as a sister lineage to morphologically similar Stauridium tetras. These new data add to our understanding of evolutionary trends in the Hydrodictyaceae, whose members exhibit specific colonial morphology varying in size, shape, and complexity.
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