Akinetes (spores) of the green, filamentous alga Pithophora oedogonia (Montagne) Wittrock were more copper resistant than filamentous cells, tolerating copper concentrations as high as 4 μg·ml-1 (16 μg·ml-1 copper sulfate pentahydrate). The localization of copper in viable and nonviable cells was conducted using cell fractionation and cytochemical/ultrastructural methods. In copper-exposed viable akinetes, copper was bound primarily to the outer layers of the cell wall. In nonviable cells, copper was found randomly distributed throughout the cytoplasmic and vacuolar regions. No evidence for compartmentation of copper as vacuolar or intranuclear deposits was demonstrated. Copper uptake into the cell wall was associated with release of equimolar amounts of calcium, magnesium, and zinc. When viable copper-treated akinetes were allowed to recover in copper-free medium, the copper was gradually released from the cell wall, presumably to the culture medium. A portion of the copper also appeared to be redistributed to new cell wall material during the akinete germination process. The differential tolerance of P. oedogonia akinetes to copper in comparison to filamentous cells appears to be due to a combination of factors that include cell surface/volume ratios, metabolic activity, and cell wall copper-binding components.

The present paper investigates standing stock variations of Halimeda opuntia on a sandstone reef of the South-west Atlantic Ocean, in order to better understand the role of this seaweed as a CaCO3 producer. The study was conducted over two 3-month periods, using photo quadrats to analyse the coverage area, and destructive sampling to quantify area-specific biomass and CaCO3 percentage. The alga occupied 2.4% of the substrate (4464 m2), growing as clumps with an average biomass of 1.59 kg m−2, resulting in a standing stock of 7097.8 kg of alga. This standing stock varied with environmental conditions, particularly wind speed. Assuming an exponential model for these variations, H. opuntia produced at least 13,050.14 kg (54.37 g m−2 day−1) of carbonate sediments. There was a positive correlation between changes in standing stock and coverage, but not with area-specific biomass. This suggests that net algal growth results in the occupation of new spaces, with minimal increases in height or segment density. Therefore monitoring coverage should complement traditional individual-based methods for estimating Halimeda growth and production. Combined, these approaches should result in more accurate models of the role of this alga on marine carbonate budgets.

A revision of the check-list of the red (Rhodophyta), green (Chlorophyta) and brown (Ochrophyta, Phaeophyceae) seaweeds of Britain has been compiled and revealed 644 taxa, mostly at species level but including infraspecific taxa: 348 reds, 110 greens and 186 browns. There were 30 additions to the list, notably five newly described species and five new non-native additions. In addition to the check-list, an updated list of non-native species was compiled based on a stringent review of the available evidence. We have listed 31 non-native species (~5% of the flora), although the numbers may be considerably higher and probably include species that are effectively naturalized and perceived to be part of the indigenous flora. The check-list is discussed in relation to the impact of molecular techniques on the identification, taxonomy and phylogeny of species, and points to the need for a comprehensive, in-depth study on the identity and relationships of the seaweeds of Britain.

Nephroselmis pyriformis (N. Carter) Ettl is reported for the first time from the north-eastern Mediterranean Sea coast. The species was isolated from the samples collected on 21 September 2013. The morphology of live cells is described based on light microscopy. Photographic and video images of the species are also presented.

A total of 34 marine algae are reported for the first time based on historical herbarium collections from the marine shores of Tonga in the central South Pacific Ocean: eight Rhodophyta and 26 Chlorophyta. One species of Rhodophyta, i.e. Trichogloea requienii, and four species of Chlorophyta, i.e. Caulerpa plumulifera, Codium extricatum, Udotea glaucescens and Valoniopsis pachynema, represent the first records from central Polynesia. The red alga Titanophora pikeana has only been previously reported in this region from the adjacent western Melanesian islands of Fiji and the isolated Hawaiian Islands to the north. The other 28 algal species are widely distributed marine species around tropical and subtropical islands in the Pacific Ocean.

In two lichen species, Hypogymnia physodes and Lecanora conizaeoides, often used as model organisms for pollution-sensitive and pollution-tolerant epiphytic lichens, respectively, the hypothesis was tested that the toxitolerance of the Trebouxia photobiont limits the tolerance of the entire lichen symbiosis. Being lecanoralean-trebouxioid associations, H. physodes and L. conizaeoides represent the most common type of lichens. Photobionts of both lichen species deriving from microhabitats with varying supply of S and heavy metals were identified using nuclear ITS nrDNA sequencing. The photobiont of L. conizaeoides was identified as T. simplex, whereas the photobiont of H. physodes belongs to an undescribed Trebouxia species, related to T. jamesii subsp. angustilobata and provisionally named as T. hypogymniae Hauck & Friedl ined. Since T. hypogymniae ined. is also known from Lecidea silacea, which is characteristic of rock and slag with high heavy metal content, a high sensitivity of this alga to pollutants is unlikely to be a key factor for the relatively low toxitolerance of H. physodes. Furthermore, the photobiont cannot be crucial for the extremely high toxitolerance of L. conizaeoides, as T. simplex is also known from pollution-sensitive lichens of the fruticose genus Pseudevernia. These findings suggest that the photobiont is not generally a key factor determining pollution sensitivity in the most common type of lichen symbiosis. The high specificity for T. simplex in L. conizaeoides in existing populations of L. conizaeoides suggest that already established thalli could be a source of photobiont cells for re-lichenization.

Major pigment patterns of 18 chlorophyceae, 7 charales, 4 euglenophyta, and 2 dinophyta isolated from freshwater ecosystems, were investigated by means of HPLC. In this study, quantitative results are presented, too, which are capable for phytoplankton quantification techniques based on pigment patterns. Chlorophyceae revealed a pattern similar to that of higher plants, but in some strains, loroxanthin as well as α-carotene were present. In charophytes, except for vegetative specimens of Chara tomentosa, γ-carotene was detected in antheridia only. Among investigated freshwater euglenophytes diadinoxanthin was the major carotenoid, with neoxanthin and ß-carotene present in minor amounts. Besides chlorophylls-a and -c, dinophytes contained high quantities of peridinin, whereas fucoxanthin was absent. An unknown component eluting just before violaxanthin showed a spectrum reminding of peridinin.

The taxonomy of Vitreochlamys species (Volvocales, Chlorophyta) was studied with light and electron microscopy; DNA sequence data were obtained for nine strains from various localities in Japan, the Czech Republic, Slovak Republic and Germany. The strains could be delineated clearly into six species – V. fluviatilis (Stein) Batko, V. gloeocystiformis (Dill) Nakazawa, comb. nov., V. ordinata (Skuja) Nakazawa, comb. nov., V. nekrassovii (Korshikov) Nakazawa, comb. nov., V. aulata (Pascher) Batko, and V. pinguis Nakazawa, sp. nov. – on the basis of differences in cell and protoplast shape, numbers of contractile vacuoles and pyrenoids, form and position of the stigma, location of the nucleus, degree of longitudinal striations on the chloroplast surface, and ultrastructure of the pyrenoid and stigma. Although V. pinguis and V. aulata share common chloroplast morphology, including stigma and pyrenoid ultrastructure, these two species can be distinguished clearly by cell shape, the number of contractile vacuoles and location of the nucleus. In addition, phylogenetic sequence data of the rbcL (large subunit of Rubisco, ribulose-1,5-bisphosphate carboxylase/oxygenase) gene from all of the Vitreochlamys strains strongly suggest that V. pinguis from Japan is robustly separated from the clade composed of four strains of V. aulata from the Czech Republic, Slovak Republic and Japan. The sequence data also showed that Vitreochlamys is composed of three clades, which are largely consistent with the ultrastructural features of the stigma and pyrenoids.

The chemical composition, biosynthesis and ultrastructural organization of the cell wall of cultures of Koliella antarctica (Klebsormidiales, Chlorophyta), a green microalga obtained from samples of sea water taken near the Italian Station of Terra Nova (Ross Sea) during the austral summer 1989–1990, have been studied. Purified cell walls of the microalga were sequentially treated with chemicals which, in higher plants, solubilize matrix polysaccharides (pectins and hemicelluloses) and leave an insoluble residue considered to be α-cellulose. CDTA plus Na2CO3- and KOH-solubilized polysaccharides were made up of glucosyl residues (more than 90 mol%), as well as some minor sugars (mannose and rhamnose). Linkage analysis and enzymic hydrolysis of the matrix polysaccharides indicated the presence of β-1,4-linked glucans with minor amounts of other uncharacterized polysaccharides. The insoluble residue was composed of a small amount of crystalline α-cellulose associated with mannan or glucomannan chains. The biosynthesis of cell wall polysaccharides was studied by incubating the microalgae in the presence of D-[U-14C]glucose or myo-[U-14C]inositol. The radioactive glycosyl residues incorporated into the polysaccharides solubilized from purified cell walls of the cultured microalga corresponded to those detected in the chemical analysis of the cell wall. The myo-inositol oxidation pathway was demonstrated to be functional in the microalga. Cell wall ultrastructural observations showed a loose network of cellulose microfibrils in an extended matrix.

Several macroalgae from the Swedish West Coast (11 green, 5 red and 11 brown algal species) and two Ulva spp. from the Mediterranean were tested for mechanisms of HCO3− utilization. In all except one (Palmaria palmata), photosynthesis supported by inorganic carbon (Ci) at pH 8.7 was rapidly and substantially (>50%) inhibited by acetazolamide (AZ), an inhibitor of extracellular carbonic anhydrase activity. This suggests that extracellular dehydration followed by uptake of the CO2 formed is an important component of the HCO3− utilization mechanism(s) of these algae. In representatives of most of the green algal genera, e.g. Enteromorpha, Ulva, Chaetomorpha and Monostroma, a specific inhibitor response could be induced. This response, a sensitivity to the anion exchange inhibitor 4,4′-diisothiocyanatostilbene-2,2′-disulphonate (DIDS) in the presence of AZ, is characteristic of an additional mechanism of HCO3− utilization, a direct import of HCO3− across the plasma membrane, which has been previously described only for some Ulva spp. and Enteromorpha intestinalis. The DIDS sensitivity could be induced in several ways, all involving a potential shortage of the supply of CO2 for photosynthesis: through photosynthesis at high pH, through growth in strong light and nutrient-rich seawater, or through photosynthesis in the presence of AZ. Induction of photosynthesis at high pH (which is a specific feature of green macroalgae) was not always accompanied by a development of this specific DIDS sensitivity; it occurred in Chaetomorpha melagonium but not in C. linum. For Ulva lactuca cultivated in natural seawater (in continuous moderate irradiance), induction of DIDS sensitivity by high pH treatment was successful all year round, except during a period in late August. The results thus suggest that green macroalgae capable of developing photosynthesis at high pH are also capable of developing a DIDS-sensitive mechanism for HCO3− uptake, but that some additional conditions (other than low CO2 availability) must be fulfilled. The ability to dehydrate extracellular HCO3− still remained after induction of the direct HCO3− uptake, and the two mechanisms for HCO3− utilization may operate independently of one another. In fact the response to DIDS was more pronounced after the addition of AZ. The possibility that the results are related to a plasticity of the HCO3−-utilizing mechanisms of green macroalgae is discussed. Neither red nor brown macroalgae showed any sensitivity to DIDS in the presence of AZ.

Ulva armoricana sp. nov. is described from the coast of Brittany, France, using the taxonomic criteria established by Bliding, Koeman and van den Hoek for the European species of Ulva. Morphological evidence strongly suggests that Ulva armoricana is conspecific with the free-living Ulva populations responsible for the ‘green tide’ phenomenon that occurs at some eutrophicated sites in North Brittany. Blades of U. armoricana are variable in shape, fragile, easily torn, and 30–55 μm thick in middle and apical regions; they differ from those of U. olivascens by their pale green colour and from those of Ulva lactuca, U. rotundata, U. gigantea, U. pseudocurvata and U. curvata by their crumpled texture that creates an irregular light-reflecting surface, and by the presence of tooth-like protuberances at the margin of the blade. U. armoricana differs from U. scandinavica in having longitudinal ribs containing closely packed bundles of rhizoids, except in the youngest thalli. U. armoricana can be discriminated from U. rigida by the polygonal (never rounded) cells in the mid-thallus region, and quadrangular cells arranged in small longitudinal rows in rapidly growing parts. Pyrenoid number, 1–2 (3–4), overlaps with that of other species, and shape of non-rhizoidal cells of the basal region in transverse sections, either oval or with tapered ends, appears not to be a good taxonomic character. Herbarium data indicate that the species has been collected in northern France since at least 1869, but was previously unrecognized.

Plasmodesmata in photosynthetic eukaryotes are found in all embryophytes, in many members of the Chlorophyta, and in the Phaeophyceae. The Phaeophyceae and the Chlorophyta clearly developed cell walls and multicellularity independently, so that (in the absence of lateral gene transfer) plasmodesmata evolved independently in these groups. The minimum number of independent origins of plasmodesmata in the Chlorophyta based on molecular phylogenies is two (Chlorophyceae sensu lato, Charophyceae sensu lato). Other intercellular connections in members of the Chlorophyta (Ctenocladus, Smithsoniella, Volvox) are structurally very different from true plasmodesmata. Recently published taxonomies of the Chlorophyta have five classes (Chlorophyceae, Oedegoniophyceae, Trentepohliophyceae, Klebsormidiophyceae and Charophyceae sensu stricto) with plasmodesmata out of a total of thirteen. However, it is by no means clear that these classes all acquired plasmodesmata independently.

Enteromorpha intestinalis grows along the Swedish west coast in rockpools which are isolated from the open seawater for long time periods and where, therefore, the inorganic carbon content is low and the pH is high during the day. In order to investigate how E. intestinalis could grow under such apparently CO2-constraining conditions, we measured its photosynthetic responses to inorganic carbon in the presence of an inhibitor of external/surface-bound carbonic anhydrase (acetazolamide) as well as an inhibitor of HCO−3 transport via anion exchange (4,4′-diisothiocyanatostilbene-2,2′-disulfonate). The results show that both HCO−3 dehydration via surface-bound carbonic anhydrase and HCO−3 transport via a 4,4′-diisothiocyanatostilbene-2,2′-disulfonate-sensitive mechanism were present in E. intestinalis, but only HCO−3 uptake via the putative transporter was operative in rockpool water during most of the photic period (pH > 9·4, inorganic carbon < 0·45 mol m−3 and CO2 < 0·05 mmol m−3). The advantage of such a mechanism, rather than extracellular HCO−3 dehydration, is discussed with regard to photosynthesis of marine macroalgae under in situ conditions conducive to high pH values adjacent to the thalli.

The past decade has seen substantial breakthroughs in understanding the biochemistry, molecular biology and regulation of nitrate reductases (NR) in higher plants and green algae. In contrast, although there has been considerable interest in using various measurements of NR to provide ecophysiological information, comparable knowledge of NR is largely lacking in algal groups other than chlorophytes. Applying information about NR from chlorophytes and higher plants to other algae may be difficult. There is evidence that non-chlorophyte forms of NR are diverse and distinct in terms of biochemical characteristics and regulatory features. Key areas to be pursued in non-chlorophyte algae include the identification and adoption of model organisms for NR research in different algal groups; the creation of selected and engineered mutants; the purification, biochemical characterization and production of antibodies to different algal forms of NR; the identification of NR genes; and the undertaking of coordinated research on nitrate uptake proteins and other enzymes in pathways of nitrate assimilation.

3050 dead molluscan shells and fragments of calcareous algae were collected from 104 benthic stations at depths from 2 to 160 m in the Firth of Clyde, the Firth of Lorne and on the Orkney shelf, British Isles. The following micro-algal borings were recognised and are described: (i) Rhodophyta: Conchocelis, (ii) Chlorophyta: Ostreobium quekettii, Eugomontia sacculata, Phaeophila sp. and (iii) Cyanophyta: Plectonema terebrans, Hyella spp.

These endolithic algae are bathymetrically zoned. Eugomontia, Phaeophila and the cyanophytes characterize the upper part of the photic zone (2–20 m). Shallow sheltered environments are typified by a high density of algal borings, most of them aligned perpendicular to shell surfaces. The lower photic zone is characterized by Ostreobium and Conchocelis whose borings are parallel to shell surfaces. The photic limit is about 40 m for the open Orkney shelf (59°N), and about 22 m for the partly enclosed firths (56°N).

The Orkney population is dominated by two chlorophyte taxa: rhodophytes and cyanophytes are absent. This may be due to higher tidal energy conditions.