Volume 49, Issue 1

Since the first collection in 1989 from Mahone Bay (Nova Scotia), the highly invasive green macroalga Codium fragile has been spreading in Atlantic Canada and has become established along the coasts of Nova Scotia, Prince Edward Island and New Brunswick. Considerable morphological variation had been found among thalli from different collection sites. This variation may be caused by the presence of different subspecies, or by phenotypic plasticity of one of the subspecies. Morphometric and molecular investigations were performed on Codium collected from seven sites in Maritime Canada and one from Maine to evaluate these hypotheses. Based on both mucron length and ISSR markers, thalli separated into three groups, suggesting multiple introductions of C. fragile into Canada. A group from the eastern shore of Nova Scotia and the coast of New Brunswick is clearly ssp. tomentosoides that likely originates from the United States. A second group, growing in Malpeque Bay in Prince Edward Island, is possibly an asexual variant of ssp. atlanticum , another invasive subspecies of C. fragile . A third group, found in Caribou Harbour only, is an intermediate in terms of both mucron length and molecular data, suggesting a hybrid of ssp. tomentosoides and ssp. atlanticum . The origin of this intermediate group remains to be established.

Variations in microphytobenthic biomass were investigated in relation to major environmental factors in the Mdloti and Mhlanga temporarily open/closed estuaries (TOCEs), South Africa, from March 2002 to March 2003. Both estuaries receive different volumes of treated sewage waters. This has caused eutrophication and an increase in the frequency of mouth opening, particularly at the Mhlanga. No significant differences were found in microphytobenthic chl a concentrations between the two estuaries. At the Mdloti, microphytobenthic biomass varied considerably, with values ranging from 1.33 to 131 mg chl a m -2 during the open phase, and from 18 to 391 mg chl a m -2 during the closed phase. At the Mhlanga, microphytobenthic biomass ranged from 7.0 to 313 mg chl a m -2 during the open phase, and from 1.7 to 267 mg chl a m -2 during the closed phase. Unlike in the Mdloti, the higher microphytobenthic biomass values at the Mhlanga were not always associated with the closed mouth state. For the duration of the study, the Mdloti functioned as a typical temporarily open/closed system, with prolonged open and closed phases, while the Mhlanga behaved more like a permanently open estuary than a TOCE (it lacked a period of prolonged mouth closure).

Despite numerous recent studies on the Gelidiales, most taxa belonging to this order are still difficult to distinguish when in the vegetative or tetrasporic state. This paper describes in detail the morphological and ontogenetic features of the prostrate system of the order with the aim of validating its diagnostic and taxonomic significance. Observations were made on fresh, liquid preserved and cultured thalli. The morphology of the attachment system and the characteristics of rhizoid ontogeny have proven to be useful diagnostic and taxonomic characters. Species belonging to Gelidium , Pterocladia and Pterocladiella bear true attachment organs consisting of cells of both exogenous and endogenous origin. In the family Gelidiellaceae, in contrast, attachment to the substratum is effected by single independent exogenous rhizoids. The attachment rhizoids of the Gelidiales, both exogenous and endogenous, are of the same cell type, and are the so-called hyphae, historically considered typical of the family Gelidiaceae only. A new subdivision of the Gelidiales into three families is proposed here, with the amendment of both Gelidiellaceae and Gelidiaceae, and the Pterocladiaceae fam. nov.

Variation in the lipid composition of the marine red alga Gracilaria verrucosa at different developmental stages was examined. Shoots, juveniles and mature tetrasporophytes, male and female gametophytes had similar qualitative lipid composition (glycolipids, phospholipids and neutral lipids). However, the ratio of these lipid groups and the content of individual lipid components depended on the developmental stage. Phospholipids were the main lipid group in shoots, due to the highest concentration of phosphatidylcholine. Glycolipids predominated in juvenile thalli as well as in tetrasporophytes, and male and female gametophytes. The content of storage lipids, i.e., triacylglycerols was 2–3 times lower in shoots and young algae compared to mature thalli. Comparison of these results with the literature on G. verrucosa thallus ultrastructure suggests that differences in lipid ratio are related to the formation and the structural alteration of cells or photosynthetic apparatus.

This study focuses on the intra-thallus variation in phlorotannin content and antioxidant activity in temperate brown seaweeds. Two species of Fucales ( Ascophyllum nodosum and Sargassum muticum ) and two species of Laminariales ( Laminaria digitata and L. hyperborea ) were collected from the shoreline of Brittany (France). Both Fucales contained high phenolic levels along their thallus (ca. 5% DW in A. nodosum and 6% DW in S. muticum ). No significant differences were found between vegetative and reproductive parts of A. nodosum . In contrast, intra-thallus and inter-specific variations were observed in phenolic contents of the two species of Laminariales studied. In L. digitata , phenolic content was about 0.2% DW, with a maximum in the holdfast, whereas in L. hyperborea , it averaged about 2.6% DW, with the highest value measured in the basal part of the old blade. In both species, phlorotannin contents were lower in the meristematic region. Intra-thallus variations of the antioxidant activity measured by the DPPH (2,2-diphenyl-1-picrylhydrazyl) method were also detected. Antioxidant activity was correlated to the phenol contents of the different parts of thalli in three species. In L. digitata , no activity was found because of low phenol levels. The observed variations in both the antioxidant activity and the phenol content could result from qualitative features of the phenolic pool.

Volatile compounds from the Black Sea red algae Bangia fuscopurpurea , Gelidium latifolium , Callithamnion granulatum , Ceramium elegans , Laurencia papillosa and Laurencia coronopus were obtained by distillation-extraction and analysed by GC/MS. Different groups of compounds were identified: hydrocarbons, alkylated benzenes, alcohols, phenols, aldehydes, ketones, acids, esters, terpenes, nitrogen- and halogen-containing compounds. The results are compared with some recent data for the composition of the volatile compounds from four previously investigated Black Sea red algae, which are at different evolutionary stages. On the basis of their qualitative and semi-quantitative composition some chemotaxonomic conclusions are proposed. The eventual functions of some of the volatile compounds are briefly discussed.

Carrageenan yield and quality from young and old tissues of Kappaphycus striatum “sacol” green variety were investigated using native and alkali-modified carrageenan extraction procedures. Dried apical (young) and basal (old) segments were pooled to produce 5 g of dried samples of each for carrageenan extraction. Mature tissues yielded greater amounts of carrageenan than young tissues. The latter exhibited higher gel strength, cohesiveness, viscosity properties and lower average-molecular weight than the mature, old tissues. FT-IR and 13 C and 1 H NMR analyses showed that both young and old tissues contained mostly the kappa-type repeating disaccharide sequences of 3-linked β-D-galactopyranose 4-sulfate (G4S) and 4-linked 3,6-anhydro-α-D-galactopyranose (DA). Moreover, the study showed that, as the algal thalli aged, the iota carrageenan (G4S-DA2S) and methlylated (G6M) carrageenan units (these were minor substituents in the major kappa-carrageenan repeating disaccharide unit) decreased in quantity. These differences suggest that the timing of galactan biosynthesis may be related to certain physiological and structural functions during the growth of the alga.

The yield and physicochemical properties of carrageenan from Eucheuma isiforme harvested at the Yucatán coast were investigated. Carrageenan was extracted under different alkali concentrations (0, 1, 3, 5 and 7% KOH) and treatment durations (3, 4 and 5 h). Native carrageenan, extracted without KOH, had the highest yield (∼44.6%) independently of treatment duration. After alkali treatment, carrageenan yield ranged from 35.3 to 31.8%. No significant differences in carrageenan yield were observed between 1 and 3% KOH. Native carrageenan had low viscosity values (39–57.0 cPs), whereas carrageenan extracted with 1% KOH at 3 and 4 h increased in viscosity (160.0–161.3 cPs). Alkali-treated carrageenan formed very weak gels (<50 g cm -2 ) in 1.5% solutions. The chemical analysis and FTIR spectra revealed a preponderantly iota-carrageenan extract. Extractions performed with 1% KOH for 3 h produced carrageenan with suitable properties to be considered as a substitute for traditional iota-carrageenan sources.

Seasonal variation in the biochemical composition and carrageenan content were studied in Eucheuma isiforme from Yucatán, Mexico. Dry weight and carrageenan yield were lowest during the late cold-early dry seasons and highest during the late rain-early cold seasons. Total carbohydrates varied seasonally and were similar to variations in carrageenan yield. The factors responsible for the seasonal variation of biochemical and carrageenan characteristics of E. isiforme from Yucatán are interrelated, and their effects are difficult to separate. Thus our results suggest that biochemical composition can be related to seawater temperature and hence to growth, while incident light and nutrients can influence the carrageenan quantity. Although no direct growth estimation has been made, changes in E. isiforme dry weight suggest that active growth starts from the late cold season throughout the dry season when seawater temperature is optimal. The above coincided with an increase in protein content and a decrease in total carbohydrates linked to reduced carrageenan synthesis. Carrageenan content is higher during the early cold season, coinciding with high nutrient concentrations and reduced light. Carrageenan yield and viscosities in E. isiforme were near levels required for Eucheuma species in industrial applications, suggesting potential commercial/industrial use of this species. These results should be taken into consideration for the management of natural populations as well as for mariculture of this species on the Yucatán coast.

The polysaccharides from an aqueous extract of a Carpopeltis species from the southeastern coast of Madagascar were examined by 13 C NMR spectroscopy. Over 80% of these polysaccharides comprised 3-linked D-galactose units that were non-substituted, 4-sulfated or 4,6-pyruvylated, and these alternated with 4-linked 3,6-anhydro-D-galactose units, some of which may have been 2-sulfated. There were also 4-linked 3,6-anhydro-L-galactose units present, which alternated primarily with 3-linked galactose-2-sulfate units. The natural extract contained 4-linked D-and L-galactose, many, but not all of which, were 6-sulfated and hence anhydrogalactose precursors, and there were minor components containing 2- O -methylanhydrogalactose, 6- O -methylgalactose, xylose, 2- O -methylgalactose, 3/4- O -methylgalactose. This is the first characterization of the galactans from a Carpopeltis species.

This paper describes some bacteria found on mangrove roots and their potential in promoting mangrove seedling growth. Forty-eight bacterial strains were isolated from rhizosphere soil of a mangrove species ( Rhizophora mucronata ). The strains were analyzed for their ability to (a) fix nitrogen, (b) solubilize phosphate, (c) produce ammonia and (d) produce the plant growth hormone (IAA); we also tested the effects of strains on shoot growth of R. mucronata . Two strains which doubled the growth of mangrove seedlings were identified as Azotobacter vinelandii and Bacillus megaterium . This raises the possibility of using the bacterial species to enhance the growth of mangrove seedlings.