J. Robert Waaland

Linnaeus was right all along: Ulva and Enteromorpha are not distinct genera

Ulva, one of the first Linnaean genera, was later circumscribed to consist of green seaweeds with distromatic blades, and Enteromorpha Link was established for tubular forms. Although several lines of evidence suggest that these generic constructs are artificial, Ulva and Enteromorpha have been maintained as separate genera. Our aims were to determine phylogenetic relationships among taxa currently attributed to Ulva, Enteromorpha, Umbraulva Bae et I.K. Lee and the monotypic genus Chloropelta C.E. Tanner, and to make any nomenclatural changes justified by our findings. Analyses of nuclear ribosomal internal transcribed spacer DNA (ITS nrONA) (29 ingroup taxa including the type species of Ulva and Enteromorphat, the chloroplast-encoded rbcL gene (for a subset of taxa) and a combined data set were carried out. All trees had a strongly supported clade consisting of all Ulva, Enteromorpha and Chloropelta species, but Ulva and Enteromorpha were not monophyletic. The recent removal of Vmbraulva olivascens (PJ.L. Dangeard) Bae et I.K. Lee from Ulvu is supported, although the relationship of the segregate genus Umhraulva to Ulvaria requires further investigation. These results, combined with earlier molecular and culture data, provide strong evidence that Ulva, Enteromorpha and Chloropelta are not distinct evolutionary entities and should not be recognized as separate genera. A comparison of traits for surveyed species revealed few synapomorphies. Because Ulva is the oldest name, Enteromorpha and Chloropclta are here reduced to synonymy with Ulva, and new combinations are made where necessary.

MACROALGAL CANDIDATES FOR GENOMICS1

Genomes from over 130 organisms have been either sequenced completely or are currently under investigation. These studies include a wide array of Bacteria, a smaller number of Archaea, model‐system eukaryotes, parasitic protists, and even several microalgae. However, no major effort is underway to acquire a complete nuclear genome sequence from a single macroalga or seaweed despite their crucial contribution to the biodiversity and energy economy of oceans and estuaries. Here we examine various macroalgae as potential candidates for a genome project. A set of criteria is presented, followed by a brief discussion of how well different candidates from the principal macroalgae groups, green, brown, and red algae, meet these criteria. Based on our analyses, we conclude that the red seaweed, Porphyra yezoensis Ueda, should be the leading candidate for a macroalgal genomics initiative. We realize, of course, that others in the phycological community might have a different opinion and that a broad consensus among algal researchers is required to make seaweed genomics a reality; thus the primary intention of this review is to initiate and encourage further discussion as to where the phycological community should focus its genomic efforts.

MOLECULAR ANALYSIS REVEALS CRYPTIC DIVERSITY IN PORPHYRA (RHODOPHYTA)1

The small subunit ribosomal RNA (SSU rRNA) gene was amplified from 15 species of the red alga Porphyra and digested with restriction enzymes to generate data for species identification. The subset of species selected for phylogenetic analysis was P. cuneiforms (Setchell et Hus) Krishnamurthy, P. nereocystis anderson, P. schizophylla Hollenberg et Abbott, P. thuretii Setchell et Dawson and Porphyra 1674. Bangia sp. was used as an out‐group. Restriction sites were mapped and used as characters in parsimony and maximum likelihood analysis. The phylogenetic hypotheses generated were compared statistically to possible alternative phylogenies based on traditional morphological taxonomic characters. The results indicate that the current subgenera in Porphyra do not represent monophyletic groups and that traditional morphological and ecological taxonomic characters alone may not be adequate for definitive species identification and cannot be relied on as an indication of Porphyra have large insertions in the SSU gene that are apparently splicesd from the final SSU rRNA molecule. The possible character, distribution and potential significance of these putative introns are discussed.

Seasonality of eelgrass, epiphyte, and grazer biomass and productivity in subtidal eelgrass meadows subjected to moderate tidal amplitude

Abstract Epiphyte and eelgrass ( Zostera marina L.) biomass and production and herbivorous gastropod ( Lacuna spp.) biomass were measured monthly for two years in a subtidal meadow subjected to moderate tidal amplitude in the San Juan Islands, WA, USA. Major physical and chemical factors (e.g., nutrient concentrations, light, and temperature) were measured concurrently. Eelgrass biomass varied from 72.2 ± 16.5 gdw m −2 in winter to 445.0 ± 78.2 gdw m −2 (mean ± 90% CI) in summer. Eelgrass productivity averaged 1767 gdw m −2 y −1 . Epiphyte biomass varied from 2.1 ± 0.8 gdw m −2 in winter to 202.3 ± 99.9 gdw m −2 in summer. Epiphyte production was 577 gC m −2 in 1990–1991 and 291 gC m −2 during 1991–1992. Light availability was the best predictor of eelgrass biomass and productivity. With the exception of ammonium, availability of water column nutrients was not positively correlated with measures of autotrophic biomass or productivity. Productivity and autotrophic biomass of this subtidal community are similar to literature maxima for intertidal meadows.

CHLOROPLAST STRUCTURE AND PIGMENT COMPOSITION IN THE RED ALGA GRIFFITHSIA PACIFICA: REGULATION BY LIGHT INTENSITY1

The ratio of accessory phycobiliproteins to chlorophyll a is controlled by light intensity in the marine red alga Griffithsia pacifica. The greatest changes in pigment ratios are observed below 300 ft‐c; above 300 ft‐c the response approaches saturation. Ultrastructural examination of chloroplasts of plants grown at different intensities reveals that the number of phycobilisomes per unit of photosynthetic thylakoid changes in direct proportion to the pigment ratios and in inverse proportion to the light intensity.

A molecular systematic study of Ulva (Ulvaceae, Ulvales) from the northeast Pacific

Abstract Species delineation in the genus Ulva is difficult due to a lack of distinguishing morphological characters and the high degree of phenotypic plasticity observed in these algae; thus, species descriptions are necessarily based on a limited set of characters. The present study uses molecular data to test species hypotheses for and explore species diversity in Ulva in the northeast Pacific. Samples of 21 taxa were collected from Valdez, Alaska to San Diego, California, additional Pacific locales outside this region, and Europe. Sequences from ITS nrDNA and the rbcL gene were analysed separately and simultaneously using maximum parsimony to reconstruct phylogeny. Molecular data resolve many of the species recognized by early and more recent treatments, reveal unanticipated potentially conspecific taxa and suggest that certain Ulva species are more widely distributed than may have been recognized previously. At least 12 species of Ulva were found in the northeast Pacific based on the present data: Ulva californica, U. intestinalis, U. lactuca, U. linza, U. lobata, U. pertusa, U. prolifera, U. pseudocurvata, U. rigida, U. stenophylla, U. taeniata and U. tanneri. Other Ulva species previously reported in this region were not encountered during the present study. In addition to providing insights into the systematics of Ulva, this paper indicates areas for additional research for this ubiquitous genus.

Reexamination of the bromophenols in the red alga Rhodomela larix

Abstract A reinvestigation of the red alga Rhodomela larix gave dipotassium 2,3-dibromo-5-hydroxy-benzyl-1′,4-disulfate and 2,3-dibromo-4,5-dihydroxybenzy] methyl ether. Aqueous hydrolysis of the salt yielded 2,3-dibromo-4,5-dihydroxybenzyl alcohol. Simple phenols reported in algae are probably artifacts of the isolation procedure.

Analysis of Cell Elongation in Red Algae by Fluorescent Labelling

SummaryThe mechanism of cell elongation in five red algae, Griffithsia pacifica Kylin, G. tenuis C. Agardh, G. globulifera Harvey, Antithamnion kylinii Gardner, and Callithamnion sp. was studied using Calcofluor White ST as a vital, fluorescent cell-wall stain. In each alga elongation of intercalary shoot cells occurs primarily by the localized addition of new cell-wall material rather than by extension of pre-existing cell wall. Cell extension is localized in narrow bands in the lateral walls of a cell; there may be one or two bands per cell and these may be located at the top or bottom of the lateral wall. The number and location of bands of elongation are constant within a species but vary from species to species. Cell walls of elongating intercalary cells of each of these algae are essentially isotropic, indicating a net random orientation of cell-wall microfibrils.

Conchospore production and seasonal occurrence of some Porphyra species (Bangiales, Rhodophyta) in Washington State

The leafy thalli of species of the marine red algal genus Porphyra grow rapidly but persist for a relatively short time on rocky intertidal or subtidal substrata or as epiphytes on other marine plants. In most species, the large, short-lived leafy thalli alternate with small, presumably perennial, filamentous ‘conchocelis’ plants. Depending on the species of northeastern Pacific Porphyra, photoperiod and temperature are important regulators of conchospore formation and release. Data from laboratory studies of conchospore formation and release in five Washington species of Porphyra (P. abottae, P. nereocystis, P. perforata, P. pseudolanceolata and P. torta) indicate that conchospores are most likely to be released at a time that precedes the appearance of the leafy thalli in the field.

Differences in carrageenan in gametophytes and tetrasporophytes of red algae

Abstract The yield and type of carrageenan in the marine red algae Iridaea cordata , I. heterocarpa , I. lineare , Gigartina exasperata and G. papillata was examined. The yield from the species studied ranged from 52 to 66%. In gametophytes, the carrageenan was 93% κ-carrageenan; in tetrasporophytes, the carrageenan was 95% γ-carrageenan.