Ecological studies on the community of drifting seaweeds in the south-eastern coastal waters of Izu Peninsula, central Japan. II: Seasonal changes in plants showing maximum stipe length in drifting seaweed communities

The authors examined seasonal patterns in 20 sargas‐saceous species (maximum stipe length of ≥45 cm) from 902 patches of drifting seaweeds in the southeastern coastal waters of the Izu Peninsula, central Japan, between spring and autumn, 1991–1993. The first analysis, dealing with plants occurring for three consecutive years, examined the top three ranked species determined from monthly pooled means of frequency of appearance in these 3 years. The second analysis examined not only the top‐ranked species in monthly means in each year, but also the continuity of appearance of species among years. The third analysis was made from dendrogram analysis based on monthly samples from each year. The first and second analyses revealed three seasonally discernible changes. From April to June, dominance shifted from Sargassum horneri (Turner) C. Agardh to Sargassum yamamotoi Yoshida with a stable transition; in July, S. yamamotoi, Sargassum macrocarpum C. Agardh, Sargassum crispi‐folium Yamada and Sargassum piluliferum (Turner) C. Agardh appeared consistently in an unstable domination with low frequency of appearance by Sargassum nipponicum Yendo, Sargassum fulvellum (Turner) C. Agardh, S. macrocarpum or S. crispifolium; in August to October, there was a stable shift from S. macrocarpum to Sargassum micracanthum (Kützing) Endlicher and Sargassum ringgoldianum Harvey. In the third analysis, monthly samples from each year were divided into four groups, characterized using the top five ranks. This characterization indicated that the top‐ranked species shifted from S. horneri to S. yamamotoi, to S. macrocarpum and to S. micracanthum with the change of seasons. Because of an overlap in the characteristic species in these three analyses, seven species (S. horneri, S. micracanthum, S. yamamotoi, S. macrocarpum, S. ringgoldianum, S. nipponicum and S. crispifolium) were regarded as dominant species. Results are compared to our previous study and it is suggested that the similarity in the pattern of plant community during seasonal changes over the period from April to June and in July resulted from both stable and unstable changes, respectively, but discrepancies in the pattern of plant community during seasonal change from August to October were the result of differences in the frequency of appearance of S. ringgoldianum and S. macrocarpum in August 1991. These results indicated that the seasonal changes of dominant species in the plant community from April to October in this study area were periodic except in July.     

Assessment of the seaweed-seagrass resource of Mararison Island,Culasi, Antique,Philippines*

A bimonthly sampling of the seaweed-seagrass resource of Mararison Island, Culasi Antique, was undertaken over 1 year to assess the species composition, similarity of taxa, and biomass (dry weight [d.w.] g m^?2) at seven localities. A total of 45 species was identified: 17 Chlorophyta, seven Phaeophyta, 15 Rhodophyta, one Cyanophyta and five seagrasses. Except for some Rhodophyta and Syringodium isoetifolium (Ascherson) Dandy, the occurrence of species between stations was not significantly different; however, differences in biomass between sampling time (month) were significant. Identical taxa between stations were determined. The highest (40) and lowest (22) number of species collected were in May and July, respectively. The species were most abundant from March to May (dry months) and sparse from July to September (wet months). The most abundant species were: Sargassum polycystum C. Agardh (399 g m^?2) (Phaeophyta), Dictyosphaeria cav-ernosa (Forsskat) Borgesen (43.1 g m^?2) (Chlorophyta), Acanthopeitis japonica Okamura (97.2 gm^?2) (Rhodophyta) and Thalassia hemprichii (Ehrenberg) Ascherson (1370 g m^?2; seagrass). The Phaeophyta were abundant in March, and the Chlorophyta and Rhodophyta in May, while the seagrasses were abundant in September. Some species occurred only during the dry months: two Phaeophyta, nine Chlorophyta and five Rhodophyta. All the seagrasses were found year-round. Almost all of the seaweeds (39/45) were found associated with seagrass. The number of seaweeds in Mararison Island was higher than for seagrasses but the total biomass of the latter was much higher than the combined biomass of the seaweeds.     

EVALUATION OF RECOVERABLE FUNCTIONAL LIPID COMPONENTS OF SEVERAL BROWN SEAWEEDS (PHAEOPHYTA) FROM JAPAN WITH SPECIAL REFERENCE TO FUCOXANTHIN AND FUCOSTEROL CONTENTS1

Fucoxanthin (Fx) and fucosterol (Fs) are characteristic lipid components of brown seaweeds that afford several health benefits to humans. This article describes the quantitative evaluation of lipids of 15 species of brown seaweeds with specific reference to Fx, Fs, and functional long‐chain omega‐6/omega‐3 polyunsaturated fatty acids (PUFAs). In addition, fatty‐acid composition of selected species was also accomplished in the study. Major omega‐3 PUFAs in the brown seaweeds analyzed were α‐linolenic acid (18:3n‐3), octadecatetraenoic acid (18:4n‐3), arachidonic acid (20:4n‐6), and eicosapentaenoic acid (20:5n‐3). Both Fx (mg · g^?1 dry weight [dwt]) and Fs (mg · g^?1 dwt) were determined to be relatively abundant in Sargassum horneri (Turner) C. Agardh (Fx, 3.7 ± 1.6; Fs, 13.4 ± 4.4) and Cystoseira hakodatensis (Yendo) Fensholt (Fx, 2.4 ± 0.9; Fs, 8.9 ± 2.0), as compared with other brown seaweed species. Studies related to seasonal variation in Fx, Fs, and total lipids of six brown algae [S. horneri, C. hakodatensis, Sargassum fusiforme (Harv.) Setch., Sargassum thunbergii (Mertens ex Roth) Kuntze, Analipus japonicus (Harv.) M. J. Wynne, and Melanosiphon intestinalis (D. A. Saunders) M. J. Wynne] indicated that these functional lipid components reached maximum during the period between January and March. The functional lipid components present in these seaweeds have the potential for application as nutraceuticals and novel functional ingredients after their recovery.     

Abundance of drifting seaweeds in eastern East China Sea

Drifting seaweeds play important ecological roles in offshore waters. Recently, large amounts of drifting seaweed rafts were found in the eastern East China Sea between the continental shelf and the oceanic front of the Kuroshio Current. However, so far there have been no quantitative reports about this particular area. Two research cruises were organized to survey abundance and standing crop of drifting seaweeds in eastern East China Sea in May 2002 and March 2004, using visual census and net sampling of drifting seaweeds. Visual census data were composed of drifting seaweed raft diameter, perpendicular distance from the transect (navigation course of the research vessel) to the raft, and positions. Using these data, we calculated the “effective stripe width” using the DISTANCE software. Drifting seaweed abundance (composed exclusively of Sargassum horneri) in waters located between the continental shelf peripheral area and the Kuroshio oceanic front was estimated to be higher than in any other area within eastern East China Sea in March and May. Abundance means in May 2002 and March 2004 were 6.14 and 29.05 rafts km⁻², respectively, while standing crop reached 126.81 and 20.35 kg km⁻² (wet weight). Mean diameter and drifting seaweed rafts in May 2002 were significantly greater than in March 2004, reflecting seasonal growth of Sargassum horneri.     

Sargassum boreale sp. nov. (Fucales, Phaeophyceae) from Hokkaido, Japan

A new species, Sargassum boreale Yoshida et Horiguchi is described. It belongs to the subgenus Bactrophycus section Teretia, with cylindrical receptacles and is distinct from Sargassum confusum C. Agardh, S. pallidum (Turner) C. Agardh and Sargassum microceratium (Turner) C. Agardh in having a rather elongated stem with smooth surface and distantly issuing main branches, with narrow leaves. The distinction between S. boreale and these species is also revealed by a difference in internal transcribed spacer 2 (ITS‐2) sequences. In addition to the base substitutions, the existence of a large gap in S. boreale distinguishes this species from others. Sargassum boreale is distributed around Hokkaido and Saghalien to 50°N latitude. A key to the species of section Teretia is provided.     

Taxonomy and distribution of Sargassum (Phaeophyceae) in the Gulf of Thailand

Ten species of Sargassum (Sargassaceae, Phaeophyceae) were found along the Gulf of Thailand. Morphological characteristics of Sargassum baccularia (Mertens) C.A. Agardh, S. binderi Sonder, S. cinereum J.G. Agardh, S.crassifolium J.G. Agardh, S. longifructum Tseng et Lu, S. oligocystum Montagne, S. polycystum C.A. Agardh, S. siliquosum J.G. Agardh, S. swartzii (Turner) C.A. Agardh and one unidentified species were examined and are described in detail. The most common species were S. polycystum distributed widely in almost all the study sites, S. crassifolium restricted to Prachuap Khirikhan Province, S. longifructum restricted to Chumphon Province, S. siliquosum restricted to Surat Thani Province and one unidentified species restricted to Songkhla Province. Three species (S. cinereum, S. longifructum and S. swartzii) are new records for the algal flora of Thailand. Five species (S. baccularia, S. cinereum, S. longifructum, S. polycystum and the unidentified species) belong to the section Zygocarpicae (J.G. Agardh) Setchell.     

Long-Term Biomonitoring of Heavy Metal Pollution of Ussuri Bay,Sea of Japan

Russian Journal of Marine Biology - The concentrations of Fe, Mn, Cu, Zn, Pb, Cd, and Ni were studied in the brown algae Sargassum miyabei Yendo and S. pallidum (Turner) C. Agardh collected in...     

LONG‐TERM CHANGES IN THE STRUCTURE OF INTERTIDAL ASSEMBLAGES AFTER INVASION BY SARGASSUM MUTICUM (PHAEOPHYTA)1

The macroalgal assemblages at the low intertidal zone were studied at three localities on the north coast of Spain between 1977 and 2002. Two of these localities were invaded at the end of the 1980s by the brown seaweed Sargassum muticum (Yendo) Fensholt (Phaeophyta, Sargassaceae), whereas the third locality remained free of the invader. In 2002, distinct algal assemblages were noticed in invaded and noninvaded localities. No major changes were detected in the noninvaded locality. Apart from the obvious presence of S. muticum, the changes observed in the invaded localities included a significant reduction in abundance of the previous dominant species (the red alga Gelidium spinosum (S. G. Gmelin) P. C. Silva) as well as an increased number of species and diversity, increased primary productivity, and variations in the seasonal abundance patterns of some species. We speculate that the arrival of S. muticum had a negative effect on the dominant native G. spinosum, probably related to competition for light. This resulted in indirect positive effects on other species of the assemblage (such as Bifurcaria bifurcata R. Ross). Other small epiphytic opportunistic species might also have been benefited from the presence of S. muticum, because the invader has a rich associated epiphytic assemblage.     

Antitumor activity of marine algae

Powdered tissue from 46 species of air-dried marine algae (four green, 21 brown and 21 red algae) were screened for antitumor activity. Significant activity against Ehrlich carcinoma was found in the brown algae Scytosiphon lomentaria (69.8% inhibition), Lessonia nigrescens (60.0%), Laminaria japonica (57.6%), Sargassum ringgoldianum (46.5%), the red algae Porphyra yezoensis (53.2%) and Eucheuma gelatinae (52.1%) and the green alga Enteromorpha prolifera (51.7%). Five brown and four red algae showed appreciable antitumor activity against Meth-A fibrosarcoma. To identify specific molecules with antitumor activity, 15 kinds of polysaccharide preparations of seaweed origin and 24 kinds of lipid fractions extracted from various seaweeds were tested. Appreciable inhibition of Ehrlich carcinoma was found for fucoidan preparations from Undaria pinnatifida and Sargassum ringgoldianum, for carrageenans and for porphyran. Several glycolipid and phospholipid fractions from brown and red algae were effective against Meth-A fibrosarcoma.     

Influence of drying treatment on three Sargassum species

The effects were investigated of two different drying treatments (oven- andfreeze-drying) on the proximate composition, amino acid profile and somephysico-chemical properties of three subtropical brown seaweeds, Sargassum hemiphyllum, S. henslowianum and S. patens. Therewere significant differences (p < 0.05, two-way ANOVA,Tukey-HSD) in the ash, crude lipid and moisture contents of the threespecies treated by the two drying methods. The amount of total aminoacids in the oven-dried seaweed samples was significantly (p <0.05, two-way ANOVA, Tukey-HSD) lower than that of the freeze-driedones. However, there were no significant differences on the amount oftotal essential amino acids and individual amino acid between the oven- andfreeze-dried brown seaweeds. Physico-chemical properties includingswelling, water holding and oil holding capacity of the freeze-dried Sargassum species were significantly (p < 0.05, two-wayANOVA, Tukey-HSD) higher than those of the oven-dried seaweedsamples. This indicated that freeze-dried seaweeds had greater potential tobe used as food ingredients in formulated food products than oven-driedones.     

Ecological studies ofSargassum thunbergii (Mertens) O. Kuntze in Maizuru Bay,Japan Sea

Sargassum thunbergii growing on the sheltered coast of Maizuru Bay, which faces the Japan Sea, has been ecologically studied. The alga is perennial, its basal part (holdfast and stem) persisting even after its primary laterals have decayed. The alga forms a conspicuous zone especially in the summer. In the winter the plant is small and its growth is very slow. After that, with the rising of both temperature and tidal levels the alga grows progressively both in length and weight, and also forms numerous lateral branches. In summer (July to August) when the tidal levels are high (+21 cm to +43 cm), the alga is always submerged. At this time, the water temperature reaches the highest in the year (27–29 C), and the alga attains its maximum length and weight. Simultaneously, maturation occurs, and soon afterwards its primary laterals rapidly decay away, while young primary laterals beging to grow. Formae ofSargassum thunbergii (f.typicum, f.latifolia, f.nipponicum and f.swartzianum), which were established by Yendo (1907) and by Okamura (1923) are also discussed in terms of their ecology.     

New species, observations, and a list of new records of brown algae (Phaeophyceae) from the Hawaiian Islands

Two new species of brown algae (Phaeophyceae), Padina moffittiana Abbott et Huisman, sp. nov. and Cutleria irregularis Abbott et Huisman, sp. nov., are described from the Hawaiian Islands (between 19°04′N, 155°35′W and 28°25′N, 178°20′W). In addition, the new combination Cutleria canariensis is proposed for Aglaozonia canariensis. New observations are presented on Nereia intricata Yamada, a species described 67 years ago and known only from its type specimen. New records of a further 14 species are given for the Hawaiian Islands. These 17 taxa bring the total number of species of brown algae recorded for the Hawaiian Islands to 55, an increase of 28%. Of the 15 new records, two are recent ‘accidental’ introductions: Dictyota flabellata (Collins) Setchell et Gardner and Sargassum muticum (Yendo) Fensholt from California. Six records are notable because of their great distances from previously known collections: Nereia intricata Yamada from the Ryukyu Is., Japan; Discosporangium mesarthrocarpum (Meneghini) Hauck, from the Adriatic, Mediterranean, warm Atlantic and southern Australia; Distromium flabellatum Womersley, Spatoglossum macrodontum J. Agardh, and Sporochnus moorei Harvey, from Australia; Desmarestia ligulata (Lightfoot) Lamouroux from temperate and colder waters in the Pacific and Atlantic. A comparison with some Japanese species of Padina confirms that Padina japonica Yamada should be subsumed with Padina sanctae‐crucis Børgesen, as proposed earlier.     

Antioxidant activities and phenolics content of eight species of seaweeds from north Borneo

The antioxidant activity of eight edible species of Malaysian North Borneo seaweeds obtained from Sabah waters (Kudat, Tanjung Aru and Semporna) consisting of three red seaweeds (Eucheuma cottonii, E. spinosum and Halymenia durvillaei), two green seaweeds (Caulerpa lentillifera and C. racemosa) and three brown seaweeds (Dictyota dichotoma, Sargassum polycystum and Padina sp.) were determined. Methanol and diethyl ether were used as extraction solvent. The antioxidant activities were determined by two methods, TEAC (trolox equivalent antioxidant capacity) and FRAP (ferric reducing antioxidant power) assays. The total phenolic content of the extract was determined according to the Folin–Ciocalteu method and results were expressed as phloroglucinol equivalents. The methanolic extracts of green seaweeds, C. lentillifera and C. racemosa, and the brown seaweed, S. polycystum showed better radical-scavenging and reducing power ability, and higher phenolic content than the other seaweeds. The TEAC and FRAP assays showed positive and significantly high correlation (R ² = 0.89). There was a strong correlation (R ² = 0.96) between the reducing power and the total phenolic content of the seaweeds methanolic dry extracts. These seaweeds could be potential rich sources of natural antioxidants.     

Unique distribution of epiphytic Neosiphonia harveyi (Rhodomelaceae,Rhodophyta) along sargassacean hosts

Although epiphytism is generally heaviest on older portions of the host thallus and both variation and abundance of epiphytes decrease with proximity to meristematic apices, Neosiphonia harveyi (Bailey) Kim, Choi, Guiry and Saunders was frequently found on upper parts of sargassacean hosts. This study compared density, thallus length and fertility of epiphytic N. harveyi among different regions of Sargassum patens C. Agardh thalli to reveal a unique distribution pattern of this epiphyte. The majority of epiphytic N. harveyi was observed on the upper part of host thalli and was seldom seen near the basal part. Over a 3‐month period, mean epiphyte density was greater on host apices while thallus length and fertility were greater on subapical portions of host thalli, suggesting the colonization by this epiphyte near the apical part of the host. Distribution patterns of this epiphyte were similar among S. patens growing at different depths. Apical portions of S. patens appear to be more suitable substrata for N. harveyi settlement and colonization compared with other portions of the host thallus, regardless of depth.     

Volatile halocarbon emissions by three tropical brown seaweeds under different irradiances

The emission rates of eight volatile halogenated compounds by three tropical brown seaweed species collected from Cape Rachado, west coast Peninsular Malaysia, under different irradiances have been determined. A purge-and-trap sample preparation system with a gas chromatograph and mass-selective detector was used to measure a suite of halocarbons released by Sargassum binderi Sonder ex J. Agardh, Padina australis Hauck, and Turbinaria conoides (J. Agardh) Kützing. All species are widely distributed in Peninsular Malaysia, with S. binderi a dominant seaweed species at our survey site. Release of few halocarbons was found to be influenced by irradiance. Correlations were also observed between emission of certain halocarbons with photosynthetic activity, especially bromo-and iodinated compounds (0.6?<?r?<0.9; p?<?0.01) suggesting that environmental factors such as light can affect the release of these volatile halogenated compounds by the seaweeds into the atmosphere. Compared with temperate and polar brown seaweeds, tropical species, such as T. conoides, may emit higher levels of bromoform, CHBr₃, and other halocarbons. It is therefore important to investigate the contribution of tropical seaweeds towards the local atmospheric composition of halocarbons.     

Ecological aspects of Sargassum muticum (Fucales,Phaeophyta) in Baja California,Mexico: reproductive phenology and epiphytes

The reproductive phenology and epiphytic macroalgae of Sargassum muticum were studied through an annual cycle (September 1987 to November 1988) at two sites on the northwestern coast of Baja California, Mexico, which were subjected to different degrees of wave exposure. Sargassum muticum is a brown alga of Japanese origin, now considered a permanent member of the marine flora of Baja California. A similar reproductive development was observed at both sites, with a maximum percentage of reproductive plants from May to July (spring–summer) and minimum from December to March (winter). Reproductive plants were found throughout the year. A total of 48 species of epiphytes were identified and seasonal variation in their diversity was observed. The greatest diversity was found at the more protected site.     

Testing systematic concepts of Sargassum (Fucales, Phaeophyceae) using portions of the rbcLS operon

The taxonomic and phylogenetic concepts within the Sargassum C. Agardh (Sargassaceae) species complex were evaluated through molecular phylogenetic analyses using portions of the chloroplast encoded rbcLS Operon. According to more conservative sequences (rbcL), Turbinaria (Turner) J. Agardh is a close and well‐supported sister lineage to the Sargassum species complex and an appropriate external outgroup for analyses of subgenera and subsections within Sargassum. Both rbcL and more rapidly evolving rbcLS spacer sequences indicated that the East Asiatic genus Myagropsis (Mertens et Turner) Fensholt, along with Sargassum sinicola Setchell et Gardner, represent the closest lineage to Sargassum and form appropriate internal outgroups. The rbcLS spacer region supported three of four subgeneric designations by J. Agardh and sectional levels within the subgenus Sargassum. However, some aspects of Agardh's system were not supported: many of the subsectional ranks or the phyletic concepts; Phyllotrichia was not monophyletic as a subgenus, and its species were also not the most ancestral of Sargassum; and subgenus Sargassum was not the most derived subgenus within the genus. This modern phylogeny suggests a deep evolutionary history for subgenus Sargassum with rapid speciation in closely related subsections and series, and a sister relationship between subgenera Arthrophycus and Bactrophycus.     

Influence of drying treatment on three Sargassum species 2. Protein extractability, in vitro protein digestibility and amino acid profile of protein concentrates

The effects of different drying treatments (oven- andfreeze-drying) on protein extractability of three subtropical brownseaweeds, Sargassum hemiphyllum, S. henslowianum and S. patens, as well as in vitro protein digestibility and amino acid profileof their protein concentrates (PCs) were investigated. When comparedwith freeze-drying, oven-drying not only improved significantly (p <0.05, two-way ANOVA, Tukey-HSD) the protein extractability of thethree Sargassum species but also the protein quality (in vitroprotein digestibility) of their PCs. Therefore, oven-drying was found to bemore suitable for protein extraction of brown seaweeds. The relationshipsbetween the protein extractability and total phenolic content in seaweedsand between in vitro protein digestibility and total phenolic contentin PCs were also discussed.     

Use of RAPD in differentiation of selected species of <Emphasis Type="Italic">Sargassum</Emphasis> (Sargassaceae,Phaeophyta)

Sargassum C. Agardh is one of the most common but little understood genera of Phaeophyta in Malaysia. The difficulty in species delineation is due to morphological plasticity. A combination of morphology and random amplified polymorphic DNA (RAPD) studies of selected Sargassum species was carried out to have a better understanding of the taxonomy. Primer OPA13 was found to be good for discriminating between Sargassum species. Sargassum binderi was shown to be different from S. oligocystum (S_D>0.5 = 14.11%), indicating the importance of the vesicle and receptacle in species differentiation. S. baccularia was clearly separated out from S. polycystum and S. stolonifolium using primer OPA13. RAPD analysis showed that the presence of the stolon is an important character for separating S. baccularia (no stolon) from S. polycystum (stolon) and S. stolonifolium (stolon). Presented at the 6th Meeting of the Asian Pacific Society of Applied Phycology, Manila, Philippines.