cometadata/datacite-titles-descriptions-related-identifiers huggingface dataset:
DOI: 10.6084/m9.figshare.12320099
title: Spatio-temporal variability and association of diatom-dinoflagellate assemblages of <i>Acanthophora, Hypnea</i> and <i>Gracilaria</i> (Rhodophyta)

description: Epiphytic microalgae can significantly affect the host seaweed either by complementing, or competing for, resources. Here, epiphytic diatom and dinoflagellate species assemblages on the macroalgae <i>Acanthophora spicifera, Hypnea pannosa</i> and <i>Gracilaria salicornia</i> collected during the north-east (February), inter- (April) and south-west (June) monsoons in 2015 along the coast of Lucero, Pangasinan, North-western Philippines were examined and characterized. Results showed that diatom–dinoflagellate assemblages strongly clustered by season rather than by geographic location. Within season, a minor clustering by macroalgal forms, rather than host species identity, was also observed, which could be associated with the differences in the complexity and texture of the upright and prostrate seaweeds. Examination of the ‘thallisphere’ using confocal laser scanning microscopy further revealed the close proximity of some of the ‘resident’ epiphytic species to the cortical cells of the host, causing deformities and implying more complex interactions. Our results suggest that epiphytic community assemblages were influenced by both the environmental conditions associated with seasonal variation and the microhabitats in the surface of the different algal forms.
DOI: 10.6084/m9.figshare.12320099.v1
title: Spatio-temporal variability and association of diatom-dinoflagellate assemblages of <i>Acanthophora, Hypnea</i> and <i>Gracilaria</i> (Rhodophyta)

description: Epiphytic microalgae can significantly affect the host seaweed either by complementing, or competing for, resources. Here, epiphytic diatom and dinoflagellate species assemblages on the macroalgae <i>Acanthophora spicifera, Hypnea pannosa</i> and <i>Gracilaria salicornia</i> collected during the north-east (February), inter- (April) and south-west (June) monsoons in 2015 along the coast of Lucero, Pangasinan, North-western Philippines were examined and characterized. Results showed that diatom–dinoflagellate assemblages strongly clustered by season rather than by geographic location. Within season, a minor clustering by macroalgal forms, rather than host species identity, was also observed, which could be associated with the differences in the complexity and texture of the upright and prostrate seaweeds. Examination of the ‘thallisphere’ using confocal laser scanning microscopy further revealed the close proximity of some of the ‘resident’ epiphytic species to the cortical cells of the host, causing deformities and implying more complex interactions. Our results suggest that epiphytic community assemblages were influenced by both the environmental conditions associated with seasonal variation and the microhabitats in the surface of the different algal forms.
DOI: 10.6084/m9.figshare.9206234
title: The diatom <i>Chaetoceros socialis</i>: spore formation and preservation

description: Planktonic diatoms thrive in the water column, and several species can transform into resting stages – spores or resting cells – that sink to the bottom of the sea. Resting stages are generally produced when environmental conditions are not optimal for growth and can remain viable in sediments for a long time. We tested different aspects related to the formation of spores in <i>Chaetoceros socialis</i>, one of the dominant diatoms in the Gulf of Naples (Mediterranean Sea, Italy). Observations in time lapse and confocal laser scanning microscopy allowed illustration of the formation of endogenous spores, in which valve deposition is accompanied by an acytokinetic nuclear division. The complete transition from vegetative cell to spore takes about 8–10 h and, if exposed to the light, spores can germinate again after a few days. The depletion of nitrogen source in the culture medium induced the formation of spores, with very similar dynamics among different sympatric strains; extremely high percentages of spores (up to &gt;95%) were produced after 4–5 days. Once formed, spores can remain viable for up to nine months, and anoxic conditions favour their preservation. Identical dynamics of spore formation were detected in freshly established cultures and in cultures produced by the germination of spores kept dormant for different lengths of time. Our results suggest that spores of <i>C. socialis</i> can, in principle, rapidly shift between vegetative cells and resting stages that may explain the success of this species in coastal water. Our results also demonstrate that storage of resting spores may represent an alternative to cryopreservation.
DOI: 10.6084/m9.figshare.9206234.v2
title: The diatom <i>Chaetoceros socialis</i>: spore formation and preservation

description: Planktonic diatoms thrive in the water column, and several species can transform into resting stages – spores or resting cells – that sink to the bottom of the sea. Resting stages are generally produced when environmental conditions are not optimal for growth and can remain viable in sediments for a long time. We tested different aspects related to the formation of spores in <i>Chaetoceros socialis</i>, one of the dominant diatoms in the Gulf of Naples (Mediterranean Sea, Italy). Observations in time lapse and confocal laser scanning microscopy allowed illustration of the formation of endogenous spores, in which valve deposition is accompanied by an acytokinetic nuclear division. The complete transition from vegetative cell to spore takes about 8–10 h and, if exposed to the light, spores can germinate again after a few days. The depletion of nitrogen source in the culture medium induced the formation of spores, with very similar dynamics among different sympatric strains; extremely high percentages of spores (up to &gt;95%) were produced after 4–5 days. Once formed, spores can remain viable for up to nine months, and anoxic conditions favour their preservation. Identical dynamics of spore formation were detected in freshly established cultures and in cultures produced by the germination of spores kept dormant for different lengths of time. Our results suggest that spores of <i>C. socialis</i> can, in principle, rapidly shift between vegetative cells and resting stages that may explain the success of this species in coastal water. Our results also demonstrate that storage of resting spores may represent an alternative to cryopreservation.
DOI: 10.6084/m9.figshare.9976055
title: Reassessment of the genus <i>Lophurella</i> (Rhodomelaceae, Rhodophyta) from Australia and New Zealand reveals four cryptic species

description: Cryptic diversity is common in the red algae and is often discovered when comparing specimens from distant locations or different morphotypes of species with high phenotypic plasticity. The genus <i>Lophurella</i> includes seven species from the cold-temperate coasts of the southern hemisphere. <i>L. periclados</i> is the only species reported from Australia where two morphotypes were identified in relation to levels of wave exposure. In New Zealand, three species of <i>Lophurella</i> have been reported – the endemic <i>L. caespitosa</i> (type locality Parimahu, North Island of New Zealand), <i>L. hookeriana</i> (type locality Cape Horn, South America) and <i>L. periclados</i>. We reassessed species diversity of <i>Lophurella</i> in Australia and New Zealand with the aim of determining (1) whether New Zealand and South American specimens of <i>L. hookeriana</i> actually represent a single species, and (2) if the morphotypes of <i>L. periclados</i> mask cryptic diversity. We studied <i>rbc</i>L sequences and morphological features of 36 specimens identified as <i>L. periclados</i>, one specimen of <i>L. caespitosa</i>, and five samples of <i>L. hookeriana</i>, three from New Zealand and two from Cape Horn. Molecular analyses revealed that <i>L. hookeriana</i> from New Zealand and South America are distinct species and the new species <i>L. pauciramulosa</i> is described from New Zealand. <i>L. periclados</i> is a complex involving four species and we propose three new species, <i>L. mutabilis, L. nigra</i> and <i>L. tasmanica</i>. Cryptic diversity in <i>L. periclados</i> did not align with the previously defined ecotypes and several species were often found at the same site. <i>L. periclados, L. nigra</i> and <i>L. tasmanica</i> can be distinguished by morphological characters. Conversely, <i>L. mutabilis</i> has high morphological plasticity, with characters that overlap with <i>L. periclados</i> and <i>L. nigra</i>, and can only be distinguished by DNA sequences.
DOI: 10.6084/m9.figshare.11940471
title: Boom-bust of <i>Sargassum muticum</i> in northern Spain: 30 years of invasion

description: The brown seaweed <i>Sargassum muticum</i> is one of the best-studied invasive marine species, although most studies are short-term and focus on the expansion phase of invasion. Here I report 30 years of observations of the invasion of the north coast of Spain by <i>S. muticum</i> at regional (400 km coastline) and local scales (at the site where the invasion was first detected). At the local scale, this long-term series reveals a ‘boom-bust’ process where the expansion (‘boom’) phase lasted 12 years and the decline (‘bust’) was completed in 8 years. This cycle is supported by evidence at the regional scale. The impact of <i>S. muticum</i> on the recipient assemblages was only moderate during the initial ‘boom’ phase of the invasion and negligible afterwards. In conclusion, 30 years after its first observation in the region, <i>Sargassum muticum</i> can be considered an addition to the algal flora rather than a threat to the native assemblages.
DOI: 10.6084/m9.figshare.9206234.v1
title: The diatom <i>Chaetoceros socialis</i>: spore formation and preservation

description: Planktonic diatoms thrive in the water column, and several species can transform into resting stages – spores or resting cells – that sink to the bottom of the sea. Resting stages are generally produced when environmental conditions are not optimal for growth and can remain viable in sediments for a long time. We tested different aspects related to the formation of spores in <i>Chaetoceros socialis</i>, one of the dominant diatoms in the Gulf of Naples (Mediterranean Sea, Italy). Observations in time lapse and confocal laser scanning microscopy allowed illustration of the formation of endogenous spores, in which valve deposition is accompanied by an acytokinetic nuclear division. The complete transition from vegetative cell to spore takes about 8–10 h and, if exposed to the light, spores can germinate again after a few days. The depletion of nitrogen source in the culture medium induced the formation of spores, with very similar dynamics among different sympatric strains; extremely high percentages of spores (up to &gt;95%) were produced after 4–5 days. Once formed, spores can remain viable for up to nine months, and anoxic conditions favour their preservation. Identical dynamics of spore formation were detected in freshly established cultures and in cultures produced by the germination of spores kept dormant for different lengths of time. Our results suggest that spores of <i>C. socialis</i> can, in principle, rapidly shift between vegetative cells and resting stages that may explain the success of this species in coastal water. Our results also demonstrate that storage of resting spores may represent an alternative to cryopreservation.
DOI: 10.6084/m9.figshare.9959723.v1
title: One hundred years later, resurrection of <i>Tydemania gardineri</i> A. Gepp & E. Gepp (Udoteaceae, Chlorophyta) based on molecular and morphological data

description: Weber-van Bosse is a genus belonging to the family Udoteaceae (Bryopsidales, Chlorophyta) and currently thought to be monospecific throughout its distribution range in the Indo-Pacific. We tested the assumption that <i>Tydemania</i> is a single species using species delimitation methods, morphological observations and phylogenetic reconstructions of large datasets. Our molecular and morphological data recovered two distinct groups, which we argue are the type species <i>T. expeditionis</i> Weber-van Bosse and <i>T. gardineri</i> A. Gepp & E. Gepp. The latter is currently considered a synonym of the former and we resurrect this name from synonymy. <i>T. gardineri</i> is distinguished morphologically from <i>T. expeditionis</i> by the complete absence of glomeruli, whereas <i>T. expeditionis</i> can have glomeruli and flabella, glomeruli alone, or flabella alone. The two species can also be distinguished by the shape and length of the stalks at the base of the flabellum, the diameter of the main axis and of the flabella siphons at the apices. In addition, they have different geographic distributions, with <i>T. gardineri</i> restricted to the Western Indian Ocean, and <i>T. expeditionis</i> extending from the Red Sea, throughout the Indian Ocean and into the West Pacific, including the Coral Triangle, the Philippines and Japan. From our dataset and literature search, we hypothesize that its south-western distribution limit is in northern Madagascar. Finally, we confirm the synonymization of <i>T. mabahithae</i> with <i>T. expeditionis</i> based on specimens from the type locality of the former and the lack of flabella in several other specimens of <i>T. expeditionis.</i>
DOI: 10.6084/m9.figshare.9976055.v1
title: Reassessment of the genus <i>Lophurella</i> (Rhodomelaceae, Rhodophyta) from Australia and New Zealand reveals four cryptic species

description: Cryptic diversity is common in the red algae and is often discovered when comparing specimens from distant locations or different morphotypes of species with high phenotypic plasticity. The genus <i>Lophurella</i> includes seven species from the cold-temperate coasts of the southern hemisphere. <i>L. periclados</i> is the only species reported from Australia where two morphotypes were identified in relation to levels of wave exposure. In New Zealand, three species of <i>Lophurella</i> have been reported – the endemic <i>L. caespitosa</i> (type locality Parimahu, North Island of New Zealand), <i>L. hookeriana</i> (type locality Cape Horn, South America) and <i>L. periclados</i>. We reassessed species diversity of <i>Lophurella</i> in Australia and New Zealand with the aim of determining (1) whether New Zealand and South American specimens of <i>L. hookeriana</i> actually represent a single species, and (2) if the morphotypes of <i>L. periclados</i> mask cryptic diversity. We studied <i>rbc</i>L sequences and morphological features of 36 specimens identified as <i>L. periclados</i>, one specimen of <i>L. caespitosa</i>, and five samples of <i>L. hookeriana</i>, three from New Zealand and two from Cape Horn. Molecular analyses revealed that <i>L. hookeriana</i> from New Zealand and South America are distinct species and the new species <i>L. pauciramulosa</i> is described from New Zealand. <i>L. periclados</i> is a complex involving four species and we propose three new species, <i>L. mutabilis, L. nigra</i> and <i>L. tasmanica</i>. Cryptic diversity in <i>L. periclados</i> did not align with the previously defined ecotypes and several species were often found at the same site. <i>L. periclados, L. nigra</i> and <i>L. tasmanica</i> can be distinguished by morphological characters. Conversely, <i>L. mutabilis</i> has high morphological plasticity, with characters that overlap with <i>L. periclados</i> and <i>L. nigra</i>, and can only be distinguished by DNA sequences.
DOI: 10.6084/m9.figshare.9959723
title: One hundred years later, resurrection of <i>Tydemania gardineri</i> A. Gepp & E. Gepp (Udoteaceae, Chlorophyta) based on molecular and morphological data

description: Weber-van Bosse is a genus belonging to the family Udoteaceae (Bryopsidales, Chlorophyta) and currently thought to be monospecific throughout its distribution range in the Indo-Pacific. We tested the assumption that <i>Tydemania</i> is a single species using species delimitation methods, morphological observations and phylogenetic reconstructions of large datasets. Our molecular and morphological data recovered two distinct groups, which we argue are the type species <i>T. expeditionis</i> Weber-van Bosse and <i>T. gardineri</i> A. Gepp & E. Gepp. The latter is currently considered a synonym of the former and we resurrect this name from synonymy. <i>T. gardineri</i> is distinguished morphologically from <i>T. expeditionis</i> by the complete absence of glomeruli, whereas <i>T. expeditionis</i> can have glomeruli and flabella, glomeruli alone, or flabella alone. The two species can also be distinguished by the shape and length of the stalks at the base of the flabellum, the diameter of the main axis and of the flabella siphons at the apices. In addition, they have different geographic distributions, with <i>T. gardineri</i> restricted to the Western Indian Ocean, and <i>T. expeditionis</i> extending from the Red Sea, throughout the Indian Ocean and into the West Pacific, including the Coral Triangle, the Philippines and Japan. From our dataset and literature search, we hypothesize that its south-western distribution limit is in northern Madagascar. Finally, we confirm the synonymization of <i>T. mabahithae</i> with <i>T. expeditionis</i> based on specimens from the type locality of the former and the lack of flabella in several other specimens of <i>T. expeditionis.</i>
DOI: 10.6084/m9.figshare.12403130
title: DNA metabarcoding analysis of macroalgal seed banks on shell surface of the limpet <i>Niveotectura pallida</i>

description: In macroalgal restoration on urchin barren coasts, understanding the variability in microscopic stages of canopy-forming macroalgae such as kelps and fucoids is critical to reduce restoration effort (i.e. sea urchin removal). In the present study, we used epilithic macroalgae present on the limpet <i>Niveotectura pallida</i> to determine the macroalgal seed bank along a depth gradient of habitats (surf, turf, barren and sandy zones). We collected a total of 46 limpets in two seasons (summer: August and winter: December) and from four zones at Sashiga-hama on the north-east coast of northern Honshu, Japan. The attached organisms on the limpet shells were brushed off and identified using a plastid-encoded <i>rbc</i>L gene and high throughput sequencing (HTS) based DNA metabarcoding. The original data set consisted of 432 macroalgal and 224 microalgal operational taxonomic units (OTUs). For macroalgae, 37, 190 and 205 OTUs were assigned to Ulvophyceae, Phaeophyceae and Rhodophyta, respectively. For canopy-forming macroalgal OTUs, Agaraceae, Alariaceae, Lessoniaceae, Laminariaceae and Sargassaceae were detected. In summer, the OTU was significantly richest in the sandy zone (77.0 ± 15.2 OTUs), but the difference among zones was less conspicuous in winter, ranging from 52.8 ± 16.4 to 64.3 ± 13.2 OTUs. The Shannon–Wiener diversity index showed similar patterns. The laminarialean and sargassacean OTUs were significantly the richest in the sandy zone during summer (<i>p</i> &lt; 0.001). In light of these results, macroalgal restoration (i.e. through sea urchin removal) should be initiated in summer and the sandy zone should be preferentially targeted.
DOI: 10.6084/m9.figshare.12403130.v1
title: DNA metabarcoding analysis of macroalgal seed banks on shell surface of the limpet <i>Niveotectura pallida</i>

description: In macroalgal restoration on urchin barren coasts, understanding the variability in microscopic stages of canopy-forming macroalgae such as kelps and fucoids is critical to reduce restoration effort (i.e. sea urchin removal). In the present study, we used epilithic macroalgae present on the limpet <i>Niveotectura pallida</i> to determine the macroalgal seed bank along a depth gradient of habitats (surf, turf, barren and sandy zones). We collected a total of 46 limpets in two seasons (summer: August and winter: December) and from four zones at Sashiga-hama on the north-east coast of northern Honshu, Japan. The attached organisms on the limpet shells were brushed off and identified using a plastid-encoded <i>rbc</i>L gene and high throughput sequencing (HTS) based DNA metabarcoding. The original data set consisted of 432 macroalgal and 224 microalgal operational taxonomic units (OTUs). For macroalgae, 37, 190 and 205 OTUs were assigned to Ulvophyceae, Phaeophyceae and Rhodophyta, respectively. For canopy-forming macroalgal OTUs, Agaraceae, Alariaceae, Lessoniaceae, Laminariaceae and Sargassaceae were detected. In summer, the OTU was significantly richest in the sandy zone (77.0 ± 15.2 OTUs), but the difference among zones was less conspicuous in winter, ranging from 52.8 ± 16.4 to 64.3 ± 13.2 OTUs. The Shannon–Wiener diversity index showed similar patterns. The laminarialean and sargassacean OTUs were significantly the richest in the sandy zone during summer (<i>p</i> &lt; 0.001). In light of these results, macroalgal restoration (i.e. through sea urchin removal) should be initiated in summer and the sandy zone should be preferentially targeted.
DOI: 10.6084/m9.figshare.12320111
title: Closely related dinoflagellate species in vastly different habitats – an example of a marine–freshwater transition

description: Phytoplankton are present in a large variety of aquatic environments, ranging from small freshwater ponds to the oceans. Typically, freshwater and marine species are not closely related, indicating an ancient divergence and that salinity poses a strong dispersal barrier. Here we reveal a common recent origin of two dinoflagellates that are well adapted to different habitats. <i>Gymnodinium baicalense</i> inhabits the geologically old freshwater Lake Baikal, which is located in the middle of the Eurasian continent. <i>Gymnodinium corollarium</i>, on the other hand, is a brackish water species from the Baltic Sea. Both species form blooms under ice during the spring. We generated 10 DNA sequences from these species. The partial 28S rRNA gene from <i>G. baicalense</i> and the partial 18S rRNA gene and internal transcribed spacer-2 (ITS2) from <i>G. corollarium</i> were sequenced for the first time. A more detailed description of <i>G. baicalense</i>, which was previously known only from light microscopy observations, is also provided. In the laboratory we demonstrated that <i>G. baicalense</i> is strictly adapted to fresh water, while <i>G. corollarium</i> had a wide salinity tolerance. However, the two species have almost identical morphology, identical SSU rRNA gene sequences, and only small differences in the LSU rRNA gene and ITS2. We infer a common ancestor, which was a species from the Arctic region with a tolerance to a range of salinities. Our data support the scenario that the under-ice phytoplankton community in Lake Baikal has been formed recently, even though the lake is the oldest in the world.