Agarum Clathratum Research Articles

Detection of Laminariaceae Species Based on PCR by Family-specific ITS Primers

To analyze nucleotide sequence encoding internal transcribed spacer (ITS) regions specific to the Laminariaceae family, genomic DNA was isolated from six brown algae species distributed along the east coast of Korea. These included three species from the Laminariaceae family (Agarum clathratum Dumortier, Costaria costata [C. Agardh] Saunders, and Saccharina japonica Areschoug) and two species from the Alariaceae family (Undaria pinnatifida [Harvey] Suringer and Ecklonia cava Kjellman), both in the order Laminariales, and one species from the family Sargassaceae in the order Fucales (Sargassum serratifolium). Based on a sequence analysis of ITS-1 and ITS-2 for A. clathratum, C. costata, and E. cava, oligonucleotides were designed from the regions that showed sequence conservation in Laminariaceae. Following polymerase chain reaction using three sets of primers, amplification of ITS-1 and ITS-2 was detected in reactions using genomic DNA isolated from the species belonging to Laminariaceae, but not from the species belonging to the other families. The results indicate that this method can be used for the detection and identification of Laminariaceae species.

해조류의 항산화 활성 및 아세틸콜린에스테라제 저해 활성

This study was conducted to investigate the antioxidant and acetylcholinesterase (AChE) inhibitory activities of extracts from various seaweed. The extracts of Sargassum thunbergii (91.3%), Polysiphonia morrowii (90.7%), Ecklonia cava (89.9%), and Artemisia fukudo (85.9%) showed over 80% high radical scavenging activities at the final concentration of 40 μg/mL. The Artemisia fukudo extract showed the highest inhibition activity of 30.2% on AChE at the final concentration of 10 μg/mL. The extract of Porphyra tenera, Costaria costata, Monostroma nitidum, Ecklonia cava, and Agarum clathratum against AChE at a concentration of 10 μg/mL exhibited inhibition of 26.6%, 25.3%, 23.4%, 21.7%, 20.4% and 19.9%, respectively. The bioautography results showed that the mixtures of structurally diverse compounds were thought to affect AChE inhibitory activity. These results suggest that extracts from seaweed with their high quality components may be effective in the prevention of Alzheimers disease and may be used to develop various functional food products.

Seasonal variation in kelp phlorotannins in relation to grazer abundance and environmental variables in the Alaskan sublittoral zone

Phlorotannins are common metabolites produced in kelps that can have deterrent functions against grazers. The factors dictating seasonal patterns of phlorotannin content in northeastern Pacific kelps are not well understood. This study assessed density and grazing of the gastropod Lacuna vincta on the annual canopy-forming kelp Nereocystis luetkeana and the perennial understory species Agarum clathratum, Saccharina latissima and S. groenlandica in Kachemak Bay, Alaska. In addition, we assessed seasonal patterns of environmental variables as possible drivers of phlorotannin concentrations. Phlorotannins occurred in all species, with overall lowest levels in N. luetkeana, and with different seasonal patterns among the four species. Lacuna vincta was most dense on N. luetkeana thalli in the summer and had highest grazing rates on this low-phlorotannin species. However, correlations between L. vincta density and phlorotannin content of each kelp species were not significant. Except for N. luetkeana, there were no correlations between phlorotannin levels and environmental variables. We suggest that kelp life history traits may be more important for phlorotannin patterns in these kelp species than grazers or environmental drivers.

Population dynamics of a nonindigenous epiphytic bryozoan Membranipora membranacea in the western North Atlantic: effects of kelp substrate

AB Aquatic Biology Contact the journal Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections AB 8:83-94 (2009) - DOI: https://doi.org/10.3354/ab00208 Population dynamics of a nonindigenous epiphytic bryozoan Membranipora membranacea in the western North Atlantic: effects of kelp substrate Megan I. Saunders*, Anna Metaxas Department of Oceanography, Dalhousie University, Halifax, Nova Scotia, B3H 4J1, Canada *Email: msaunders@dal.ca ABSTRACT: In rocky subtidal ecosystems of the western North Atlantic, the nonindigenous epiphytic bryozoan Membranipora membranacea facilitates the introduction of other nonindigenous benthic species by defoliating kelps. Susceptibility to infestation by the bryozoan varies among kelp species, although the causes of this variability are not known. We monitored the percent cover of the bryozoan on Saccharina longicruris, Laminaria digitata, and Agarum clathratum, at 2 to 3 depths within 3 sites over 15 mo in 2005 to 2006. To infer mechanisms of observed differences in cover, we examined patterns of colony settlement and abundance, size-frequency distributions, and the proportion of plants with overwintering bryozoans on the respective kelp species. We also quantified the distributions and abundances of kelps before and after a major defoliation event in the fall of 2006. During the peak in abundance in fall, the highest percent cover of the bryozoan was consistently observed on L. digitata, which was achieved by colonies attaining larger sizes. The lowest cover and abundance were observed on A. clathratum, a pattern that we attributed to lower recruitment. Following an outbreak of the bryozoan in the fall of 2006, defoliation of the kelp bed was due to losses of individuals of S. longicruris, and to a lesser extent, A. clathratum, but not to losses of L. digitata, which increased in abundance at 1 location. Our results suggest that differences in the abundance of this introduced species among its algal hosts arise as a result of both differential settlement and survival. In turn, differential susceptibility among hosts to infestation may result in alteration of the algal community structure. KEY WORDS: Invasive species · Kelp beds · Rocky subtidal ecosystems · Epibiota · Bryozoa · Membranipora membranacea · Western North Atlantic Full text in pdf format PreviousNextCite this article as: Saunders MI, Metaxas A (2009) Population dynamics of a nonindigenous epiphytic bryozoan Membranipora membranacea in the western North Atlantic: effects of kelp substrate. Aquat Biol 8:83-94. https://doi.org/10.3354/ab00208 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in AB Vol. 8, No. 1. Online publication date: December 28, 2009 Print ISSN: 1864-7782; Online ISSN: 1864-7790 Copyright © 2009 Inter-Research.

Fatty acid profiles in the gonads of the sea urchin Strongylocentrotus droebachiensis on natural algal diets

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 373:1-9 (2008) - DOI: https://doi.org/10.3354/meps07746 FEATURE ARTICLE Fatty acid profiles in the gonads of the sea urchin Strongylocentrotus droebachiensis on natural algal diets Jennifer R. Kelly1,*, Robert E. Scheibling1, Sara J. Iverson1, Patrick Gagnon2 1Department of Biology, Dalhousie University, Halifax, Nova Scotia B3H 4J1, Canada 2Ocean Sciences Centre, Memorial University of Newfoundland, St. John’s, Newfoundland and Labrador A1C 5S7, Canada *Email: jennifer.kelly@dal.ca ABSTRACT: We examined fatty acid (FA) compositions of gonads of the green sea urchin Strongylocentrotus droebachiensis collected from a grazing aggregation (front) at the edge of a kelp bed and from barrens dominated by coralline algae, and those of urchins fed single algal diets in the laboratory. We compared these gonad FAs with those of the algal diets, which represented known urchin food sources in rocky subtidal habitats. Gonads of urchins collected from both wild habitats, and of urchins fed kelp Saccharina longicruris in the laboratory, contained more lipid than did urchins fed single diets of barrens macroalgae (Agarum clathratum, coralline red algae or Desmarestia viridis). Substantial biosynthesis of non-methylene interrupted dienes and other FAs by urchins markedly affected their overall FA signatures. Although the FA compositions of gonads of laboratory-fed urchins did not clearly correspond with those of their diets, 3 clusters of urchins were distinguished in multivariate space using multidimensional scaling (MDS): (1) urchins fed single diets of barrens macroalgae in the laboratory; (2) urchins fed S. longicruris in the laboratory or collected from the grazing front; and (3) urchins from the barrens. Characteristics of FA signatures found in urchins from the barrens suggested the occurrence of benthic diatoms in their diet. Our results indicate that, while the FA signatures of urchin gonads are affected by diet and can be used to differentiate feeding groups of urchins in the laboratory and field, significant de novo biosynthesis and/or modification of FAs precludes correspondence of urchin FAs to those of their algal diets. KEY WORDS: Fatty acid · Sea urchin · Strongylocentrotus droebachiensis · Macroalgae · Dietary tracer · Food web Full text in pdf format Information about this Feature Article NextCite this article as: Kelly JR, Scheibling RE, Iverson SJ, Gagnon P (2008) Fatty acid profiles in the gonads of the sea urchin Strongylocentrotus droebachiensis on natural algal diets. Mar Ecol Prog Ser 373:1-9. https://doi.org/10.3354/meps07746 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 373. Online publication date: December 23, 2008 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2008 Inter-Research.

KELP PATCH DYNAMICS IN THE FACE OF INTENSE HERBIVORY: STABILITY OF AGARUM CLATHRATUM (PHAEOPHYTA) STANDS AND ASSOCIATED FLORA ON URCHIN BARRENS1

The brown alga Agarum clathratum (Dumortier) is the only large, perennial, fleshy macrophyte commonly found on urchin‐dominated barrens in the northwestern North Atlantic. We examined the spatial and temporal stability of A. clathratum stands and their impact on algal recruitment in the Mingan Islands, northern Gulf of St. Lawrence. The stands were highly stable in space and time, with only small intersite variations. The percent cover of A. clathratum in 144‐m2 areas increased by 6.5%–11.4% over a 2‐year period, and most changes in abundance occurred at the edge of the stands. The surface area of small (<13 m2) single stands of A. clathratum increased by approximately 1.8%·month−1, although marked increases (>95%) occurred during winter, largely because adjacent stands merged into larger single stands. Mature stands of A. clathratum appear to enhance algal recruitment, as juvenile A. clathratum and the understory red alga Ptilota serrata (Kützing) were orders of magnitude more abundant inside than outside the stands. The experimental removal of the A. clathratum canopy (1‐m2 portions) had no long‐term effect on the abundance of A. clathratum, which within 14 months had recolonized most of the cleared areas. In contrast to juvenile A. clathratum, the abundance of P. serrata rapidly decreased after canopy removal. Our results demonstrate that A. clathratum stands are a stable component of urchin barrens in spite of the heavy grazing that typically occurs there. Maintenance and expansion of A. clathratum stands and associated flora appear to depend on positive interactions with self‐defended adult A. clathratum.

Occurrence of the gametophyte of Agarum clathratum (Laminariales, Phaeophyceae) as an endophyte in Orculifilum denticulatum (Gigartinales, Rhodophyceae)

SUMMARY An endophytic filamentous brown alga, growing in the red alga Orculifilum denticulatum Lindstrom, was collected from the north-east Pacific, near Juneau, Alaska. Within the host tissue, its branched filaments formed a network in the space between the filaments of the host tissues embedded in the host intercellular substances. Cells of the filaments contained many discoid chloroplasts without pyrenoids. Neither microscopic morphological observation nor culturing was sufficient to reveal the specific identity or even the familial affinity of the alga; in contrast, molecular phylogenetic analysis of its rbcL gene and rDNA ITS sequences showed that it was the gametophyte of Agarum clathratum Dumortier (Laminariales). There are few reports of laminarialean gametophytes in nature; this is the first report actually identifying the species of laminarialean gametophyte in a red alga.