Band 52, Heft 3

No abstract available

The long-term impacts of declining water quality from coastal development on macro-algal communities can be devastating, but are rarely known because of lack of baseline studies. This study examines the effect of increased sediment and reduced water quality over 35 years in an Australian temperate coastal embayment. The algal assemblage on Crawfish Rock in northern Western Port was surveyed in 1967–1971 and in 2002–2006. During the 1980s, water quality declined following large-scale seagrass loss. In 1971, the Rock had a rich algal flora with 138 recorded species, including 97 species of Rhodophyta. The biomass and cover of canopy and understorey species were measured at sites of strong and slight current on a depth gradient. In 1971, fucoid or laminarian canopy species were dominant from ∼1–8 m depth, and an algal understorey extended from the intertidal zone to 12–13 m depth. In 2002–2006 the canopy species extended to only 3 m depth and the algal understorey to ∼4 m depth, and 66% of the algal species had disappeared, although a few additional species were present. Persistent, sediment-tolerant species included several phaeophycean canopy species, some chlorophytes ( Caulerpa spp.) and a few rhodophytes.

Erythroglossum lusitanicum was originally described from sterile and tetrasporophytic material. The apical organization and the sexual structures have considerable relevance for classification of Delesseriaceae, and these are described here for the first time in this species. The range of morphological variability in some species of the genus Erythroglossum in Atlantic Europe has been broadened, requiring a revision of the taxonomic identity of E. lusitanicum . Reproductive characters observed in E. lusitanicum include: 1) procarps scattered over the blade surface and composed of a supporting cell bearing two 4-celled carpogonial branches and a single group of sterile cells; 2) carposporangia formed in chains; and 3) spermatangial sori consisting of two layers of spermatangial mother cells bearing spermatangia. These features, together with the Phycodrys -type apical organization, are in accordance with those described for the genus Erythroglossum . The main taxonomic features of E. lusitanicum that distinguish it from congeners in Atlantic Europe are thallus growth that occurs in each blade by means of a single apical cell located in the tip, and its turf forming habit.

In this study, 10 new records of subtidal Rhodophyta are given for the Atlantic coast of the Iberian Peninsula. Most of these species of benthic marine algae are characteristic of temperate regions. Two were known previously only for the Mediterranean Sea ( Gelidium bipectinatum and Gloiocladia microspora ), and their distribution into the Atlantic Ocean has been enlarged in this study. The northern distribution limits in the Atlantic Ocean of six other species ( Nemastoma dichotomum , Predaea ollivieri , Predaea pusilla , Platoma cyclocolpa , Sebdenia dichotoma , and Sebdenia rodrigueziana ) and the southern distribution limit of another species ( Schmitzia neapolitana ) have been expanded. Description, habitats, and distributions of the species are also given.

Eleven species of benthic marine algae from deep and shallow habitats are newly reported for Puerto Rico. These include rhodophytes: Hypneocolax stellaris, Predaea laciniosa, Botryocladia monoica, B. papenfussiana, Rhododictyon bermudense, Hypoglossum caloglossoides; heterokonts : Chrysocystis fragilis, Dictyota friabilis, D. hamifera; and chlorophytes : Boergesenia forbesii, Derbesia osterhoutii. The Puerto Rican collections of Predaea laciniosa, Boergesenia forbesi and Chrysocystis fragilis are new records for the Atlantic Ocean.

The marine red alga Lomentaria benahoarensis sp. nov. from the Canary Islands is described. Plants grow epiphytically on Corallina elongata forming turfs of creeping axes attached by lateral discoid holdfasts and erect axes up to 12 mm high. Erect axes are terete to slightly compressed, 200–300(–1000) μm broad, radially branched up to three orders, with laterals progressively thinner, constricted only at the bases of terminal axes. The cortex is three-layered with the outermost cortical cells arranged in a near-continuous surface layer. Medullary filaments form a loose network of narrow elongate cells, which bear secretory cells. Gametophytes are dioecious with spermatangia formed in continuous spermatangial sori; cystocarps are urceolate and ostiolate. Tetrasporangia are subspherical and formed in depressed rounded sori in slightly swollen regions in the middle of fertile terminal axes. The new species has no single unique feature, but differs from the other Lomentaria species by a distinctive combination of attributes. Closest related species to Lomentaria benahoarensis appear to be L. corallicola , L. gracillima , L. monochlamydea , L. orcadensis , L. rawitscheri , and L. tenerrima . Although all these species have a diminutive, decumbent habit and lack regular constrictions in axes, the number of cortical cell layers and the arrangement of outer cortical cells distinguish them.

The original description of Halymenia actinophysa was based on few thalli and limited characteristics. Moreover, later descriptions seem to have included more than one species; the confusion of identity was exacerbated by the lack of carposporangial material. From 1995 to 2006, extensive collections of this species were made at several locations (including the type locality) in the southwestern part of the Gulf of California. The study focused on gametangial material. Our aim was to analyze the morphology and anatomy of this species (based on vegetative and reproductive features) to better understand species discrimination. Halymenia actinophysa is a foliose alga with orbiculate to elliptical ruffled blades and a gelatinous, membranous, slippery frond texture. In transverse section, the blade has a thickness of 150–300 μm, a cortex with one or two rounded or elongated cells and an internal layer with elongated, stellate cells connected to the anticlinal filaments of the medulla. Reproductive anatomy is in agreement with the modern concept of the genus and supports the concept that earlier descriptions comprised a mixture of species. The present study strongly suggests the need for a formal review of the genus Halymenia in the Gulf of California to delimit the species and to relate them to other genera of the same family.

In the absence of type specimens, a lectotype of Antithamnion nipponicum is selected here from the original illustrations of the protologue. The lectotype is in agreement with the original description and shows characters that allow unequivocal identification with an undated Yamada specimen from a syntype locality. The latter specimen is selected here as epitype. It is concluded that Antithamnion nipponicum is a heterotypic synonym of Antithamnion pectinatum , and that the correct name of the species currently passing under the name A. nipponicum should be Antithamnion hubbsii .

The extraction of metabolites of industrial interest from seaweed tissue is difficult due to the presence of anionic polysaccharides in the cell walls. We studied enzymatic digestion of Grateloupia turuturu (Rhodophyta) to facilitate extraction of the desired metabolites from this seaweed. Four polysaccharidases (Onozuka R-10 cellulase, agarase, κ- and ι-carrageenases) were used alone and in combination. We studied the efficiency of the enzymatic process in degrading the seaweed thallus; we also investigated the effect of the enzymatic treatment on solubilization of R-phycoerythrin and reducing sugars. The best degradation conditions for Grateloupia thalli were obtained with cellulase alone (0.48 U ml -1 ), or with a combination of cellulase/κ-carrageenase. However, only the combination cellulase (0.08 U ml -1 )/κ-carrageenase (0.01 U ml -1 ), or the individual enzymes [agarase or ι-carrageenase at low concentration (0.55 U ml -1 and 2.5×10 -3  U ml -1 )] improved solubilization of R-phycoerythrin compared to the control conditions. The simultaneous use of polysaccharidases enabled solubilization of a large quantity of reducing sugars (40 mg glu g -1 dw). Therefore, this condition appears suitable for the production of oligosaccharides. This result also confirms indirectly the presence of agar, cellulose, κ- and ι-carrageenans in the cell wall of Grateloupia turuturu .

We assessed the antioxidant activity of crude extracts from 24 rhodophyte species from Brittany coasts using three complementary methods (2,2-diphenyl-1-picryhydrazyl, reducing activity, and β-carotene-linoleic acid system). We also examined phenolic contents. Cytotoxic activities were determined with three different cancer cell lines. Four species ( Aglaothamnion pseudobyssoides , Furcellaria fastigiata , Polysiphonia lanosa , and Heterosiphonia plumosa ) had high antioxidant activity and high phenolic content. The extract from Brongniartella byssoides had the highest antioxidant potential, which was also found to be equivalent to the antioxidant activities of some commercial antioxidants. In the β-carotene system, extracts from Porphyra leucosticta and Porphyra purpurea had some specific antioxidant activity. Furthermore, Asparagopsis armata , B. byssoides and H. plumosa extracts had strong cytotoxic activities against Daudi and Jurkat cells.

With the aim of solubilizing R-phycoerythrin from Grateloupia turuturu , we tested the efficiency of two extraction solutions (distilled water and phosphate buffer) on fresh and freeze-dried seaweeds. Three different methods enabling a partial purification of this pigment were also tested: ammonium sulfate precipitation, separation in aqueous two-phase systems, and ultrafiltration. The best extraction and partial purification conditions for R-phycoerythrin were observed from freeze-dried algae after application of the precipitation procedure (80% ammonium sulfate). This latter protocol appears to be efficient for separating R-phycoerythrin without denaturation from most proteins and other components (such as sugars) that limit the purification of phycobiliproteins.

No abstract available