Wendy A. Nelson

Calcified macroalgae – critical to coastal ecosystems and vulnerable to change: a review

Calcified macroalgae are distributed in marine habitats from polar to tropical latitudes and from intertidal shores to the deepest reaches of the euphotic zone. These algae play critical ecological roles including being key to a range of invertebrate recruitment processes, functioning as autogenic ecosystem engineers through provision of three-dimensional habitat structure, as well as contributing critical structural strength in coral reef ecosystems. Calcified macroalgae contribute significantly to the deposition of carbonates in coastal environments. These organisms are vulnerable to human-induced changes resulting from land and coastal development, such as altered patterns of sedimentation, nutrient enrichment through sewage and agricultural run-off, and are affected by coastal dredging and aquaculture. The consequences of increasing sea surface temperatures and fundamental changes in the carbon chemistry of seawater due to CO2 emissions from anthropogenic activities will have serious impacts on calcifying macroalgae. It is not yet understood how interactions between a range of variables acting at local and global scales will influence the viability of calcifying macroalgae and associated ecosystems. Research is urgently needed on all aspects of the taxonomy, biology and functional ecology of calcifying macroalgae. Without an understanding of the species present, measurement of change and understanding species-specific responses will not be possible.

A NEW LOOK AT AN ANCIENT ORDER: GENERIC REVISION OF THE BANGIALES (RHODOPHYTA)†

The red algal order Bangiales has been revised as a result of detailed regional studies and the development of expert local knowledge of Bangiales floras, followed by collaborative global analyses based on wide taxon sampling and molecular analyses. Combined analyses of the nuclear SSU rRNA gene and the plastid RUBISCO LSU (rbcL) gene for 157 Bangiales taxa have been conducted. Fifteen genera of Bangiales, seven filamentous and eight foliose, are recognized. This classification includes five newly described and two resurrected genera. This revision constitutes a major change in understanding relationships and evolution in this order. The genus Porphyra is now restricted to five described species and a number of undescribed species. Other foliose taxa previously placed in Porphyra are now recognized to belong to the genera Boreophyllum gen. nov., Clymene gen. nov., Fuscifolium gen. nov., Lysithea gen. nov., Miuraea gen. nov., Pyropia, and Wildemania. Four of the seven filamentous genera recognized in our analyses already have generic names (Bangia, Dione, Minerva, and Pseudobangia), and are all currently monotypic. The unnamed filamentous genera are clearly composed of multiple species, and few of these species have names. Further research is required: the genus to which the marine taxon Bangia fuscopurpurea belongs is not known, and there are also a large number of species previously described as Porphyra for which nuclear SSU ribosomal RNA (nrSSU) or rbcL sequence data should be obtained so that they can be assigned to the appropriate genus.

A NEW LOOK AT AN ANCIENT ORDER: GENERIC REVISION OF THE BANGIALES (RHODOPHYTA)(1).

The red algal order Bangiales has been revised as a result of detailed regional studies and the development of expert local knowledge of Bangiales floras, followed by collaborative global analyses based on wide taxon sampling and molecular analyses. Combined analyses of the nuclear SSU rRNA gene and the plastid RUBISCO LSU (rbcL) gene for 157 Bangiales taxa have been conducted. Fifteen genera of Bangiales, seven filamentous and eight foliose, are recognized. This classification includes five newly described and two resurrected genera. This revision constitutes a major change in understanding relationships and evolution in this order. The genus Porphyra is now restricted to five described species and a number of undescribed species. Other foliose taxa previously placed in Porphyra are now recognized to belong to the genera Boreophyllum gen. nov., Clymene gen. nov., Fuscifolium gen. nov., Lysithea gen. nov., Miuraea gen. nov., Pyropia, and Wildemania. Four of the seven filamentous genera recognized in our analyses already have generic names (Bangia, Dione, Minerva, and Pseudobangia), and are all currently monotypic. The unnamed filamentous genera are clearly composed of multiple species, and few of these species have names. Further research is required: the genus to which the marine taxon Bangia fuscopurpurea belongs is not known, and there are also a large number of species previously described as Porphyra for which nuclear SSU ribosomal RNA (nrSSU) or rbcL sequence data should be obtained so that they can be assigned to the appropriate genus.

Genetic diversity in Undaria pinnatifida (Laminariales, Phaeophyceae) deduced from mitochondria genes – origins and succession of introduced populations

S. Uwai, W. Nelson, K. Neill, W.D. Wang, L.E. Aguilar-Rosas, S.M. Boo, T. Kitayama and H. Kawai. 2006. Genetic diversity in Undaria pinnatifida (Laminariales, Phaeophyceae) deduced from mitochondria genes – origins and succession of introduced populations. Phycologia 45: 687–695. DOI: 10.2216/05-66.1 To elucidate the genetic diversity of the brown alga Undaria pinnatifida in native and introduced populations worldwide, and to discuss the transoceanic introduction processes, we investigated the haplotype divergence of the mitochondrial loci of the coding region of cox3 and noncoding region between tatC and tLeu genes. In its native range (Japan, Korea and China), we found 27 haplotypes, which were classified into 4 genetic and biogeographical groups: (1) Northern Japan type, distributed in Hokkaido and Pacific northern Honshu; (2) Continental type, found in Korea and China; (3) Pacific central Japan type; and (4) Sea of Japan type. Among the introduced populations, European and Mexican populations agreed with the Northern Japan type. In Australia, the Tasmanian population agreed with the Sea of Japan type, whereas the Victorian population was of the Continental type. Very high diversities were found in New Zealand: 10 haplotypes were found (including 2 only in old herbarium specimens), including both the Northern Japan type and the Continental type. The haplotype found in California agreed with a component of the Central Japan type collected at Kanagawa Prefecture. The samples from Argentina agreed with the Continental type. The alignment of the European populations with the Northern Japan type is consistent with the notion that the Undaria in Europe was first introduced with oyster spat. It is speculated that Californian and Mexican populations were recently introduced by shipping vectors. There have been many introduction events to New Zealand since the late 1980s, and the dominant haplotypes in the local populations appear to have changed over time. Introduction to Argentina/Australia (Victoria) could have resulted from secondary introductions from New Zealand populations, because transport within the same latitudinal range is considered to be easier than transport by shipping across the equator. Within Japan, the occurrence of both the Continental and the Northern Japan types in the Osaka Bay area is considered to be the result of recent intentional introduction for fisheries purposes.

Utility of psbA and nSSU for phylogenetic reconstruction in the Corallinales based on New Zealand taxa

A number of molecular studies of the Corallinales, a calcified order of the red algae, have used the conservative nSSU gene to investigate relationships within the order. However interspecific variation at this locus is low for closely related species, limiting resolution of recently diverged groups. In this study, we obtained psbA sequence data from specimens of the order from New Zealand that had been identified according to current taxonomic criteria. We compared phylogenetic analyses based on psbA with those based on nSSU for the same dataset, and also analysed nSSU sequences of the New Zealand material with nSSU sequences of Corallinales taxa from other parts of the world. Our study shows that psbA has considerable potential as a marker for this group, being easily amplified and considerably more variable than nSSU. Combined analyses using both markers provide significant support for relationships at both distal and terminal nodes of the analysis. Our analysis supports the monophyly of all three families currently defined in Corallinales: the Sporolithaceae, Hapalidiaceae and Corallinaceae, and indicates cryptic speciation in Mesophyllum and Spongites.

Phylogenetic relationships and generic concepts in the red order Bangiales: challenges ahead

Wendy A. Nelson, Tracy J. Farr and Judy E.S. Broom. 2006. Phylogenetic relationships and generic concepts in the red order Bengiales: challenges ahead. Phycologia 45: 249–259. DOI: 10.2216/05-26.1 Over the past decade molecular sequence data and phylogenetic analyses have provided strong evidence that the order Bangiales is monophyletic, but that Porphyra and Bangia as currently understood are not. Previous research on the Bangiales has focused primarily on taxa from the North Pacific and North Atlantic. Recent exploration of Bangiales diversity in other regions, particularly the southern hemisphere, has revealed deep divergences in the order in phylogenetic analyses employing the slowly evolving 18S rRNA gene. The presence of high diversity in New Zealand raises the prospect that the southern hemisphere, and particularly eastern Gondwana, is not only a centre of diversity but a centre of origin for the Bangiales. Although the need for new generic concepts within this order is clear, it is our conclusion that approaches to revising the Bangiales based solely on regional approaches will not succeed: the completion of a modern and robust taxonomic revision of this order requires a global collaborative effort. Enhanced taxon sampling and verifiable application of names, based on vouchered specimens, will be essential for this to be achieved. The determination of phylogenetic relationships in the Bangiales has implications for the qua.gification of biodiversity. The number of taxa in the evolutionarily diverse Bangiales has been significantly underestimated, and the diversity in this group has been obscured by the recognition of only two genera. Based on the analyses completed to date, in a revised Bangiales there will be at least 10 genera, 5 of which are currently recognised (Bangia, Dione, Minerva, Pseudobangia and Porphyra), as well as further genera yet to be circumscribed. The majority of species currently placed in Porphyra, including species of commercial value, will not remain in Porphyra sensu stricto.

Ulva, Umbraulva and Gemina: genetic survey of New Zealand taxa reveals diversity and introduced species

The genetic diversity of the green algal genus Ulva sensu lato in the New Zealand region was surveyed, examining rbcL sequences of 581 samples from a wide geographical range. Twenty-four genetically distinct taxa were discovered in New Zealand waters, belonging to three genera–Ulva (19 species), Umbraulva (four species) and Gemina (one species). Of the 19 species of Ulva reported here, 13 could be identified to the species level based on morphological and genetic data. The remaining six species cannot currently be assigned to known species groups due to a lack of close homology with sequences in GenBank. These species may include undescribed endemic taxa, recognised taxa for which rbcL sequences are not yet available, or may represent cryptogenic species. The genus Umbraulva is recorded for the first time for the New Zealand region and for the Southern Hemisphere. Of the four species distinguished, one is considered to be introduced to the region and the other three are undescribed indigenous taxa. Subantarctic samples provide the first evidence of the genus Gemina since its description in 1952: sequence data confirmed that Gemina is distinct from Ulva and Umbraulva. A number of the species identified in this study can be distinguished through a combination of growth form, morphological, ecological and distributional characters. However there remain considerable problems in distinguishing a number of other species by morphological characters alone. Based on information such as distribution in New Zealand (percentage of samples occurring in highly modified environments and/or areas with frequent vessel traffic), as well as the genetic similarity of New Zealand samples to material from overseas, we have concluded that at least five species have been introduced to the New Zealand region: Ulva armoricana, U. californica, U. flexuosa, U. lactuca and Umbraulva olivascens.

Phylogenetic diversity in South African Porphyra (Bangiales, Rhodophyta) determined by nuclear SSU sequence analyses

Specimens of Porphyra were collected at 10 sites along the western, southern and eastern Cape coasts of South Africa during late January to early February 2001. Sequence data from the variable V9 region of the nuclear small subunit rDNA (nSSU) locus were determined for 45 specimens. These data identified 11 distinct entities each with unique V9 sequences. Phylogenetic analyses incorporating sequences of Porphyra and Bangia from throughout the world revealed that eight of the entities examined in this study form a monophyletic group, apparently endemic to the southern African region. The other three entities exhibited no close phylogenetic relationship either with each other or with the other South African taxa. This survey indicates that the southern African coast is a repository of greater taxonomic diversity for this genus than has been previously reported.

Relationships of the Porphyra (Bangiales, Rhodophyta) flora of the Falkland Islands: a molecular survey using rbcL and nSSU sequence data

The phylogenetic relationships of Porphyra collected from the Falkland Islands have been examined using molecular data from two loci, the plastid rbcL gene and the nuclear nSSU gene, in conjunction with morphological observations. Nine species have been distinguished, belonging to four distinct lineages within the Bangiales, differing from one another by 16–137 substitutions in the rbcL gene. One species is closely related to P. amplissima, a north Atlantic taxon, three are resolved in a clade that includes several species from New Zealand, Australia and South Africa, as well as P. umbilicalis, whereas four others are more closely related to Southern Ocean species, including P. cinnamomea, P. virididentata and several as yet unnamed taxa from New Zealand, Australia and South Africa. Three species, one of which we identify as P. columbina, appear to be widely distributed in the Southern Ocean, with representatives on the Falkland Islands and on islands of the Australian and New Zealand subantarctic.

Invasive marine red alga introduced to New Zealand waters: First record of Grateloupia turuturu (Halymeniaceae, Rhodophyta)

Abstract The red alga Grateloupia turuturu is recorded from New Zealand waters for the first time. This species, native to Japan, is considered to be invasive in western Europe, North America, and Tasmania. The occurrence of G. turuturu is confirmed by molecular analysis of chloroplast‐encoded rbcL and mitochondrial cox2–3 spacer sequences as well as the vegetative and reproductive anatomy of both tetrasporophyte and gametophyte specimens.