Agarum Cribrosum Research Articles

Anti-Allergic Inflammatory Effect of Agarum cribrosum and Its Phlorotannin Component, Trifuhalol A, against the Ovalbumin-Induced Allergic Asthma Model.

Asthma is a chronic inflammatory disease involving structural changes to the respiratory system and severe immune responses mediated by allergic cytokines and pro-inflammatory mediators. Agarum cribrosum (AC) is a kind of seaweed which contains a phlorotannin, trifuhalol A. To evaluate its anti-allergic inflammatory effect against asthma, an ovalbumin inhalation-induced mouse asthma model was used. Histologic observations proved that trifuhalol A is minimizing the lung and tracheal structure changes as well as the infiltration of eosinophils and mast cells against ovalbumin inhalation challenge. From the serum and bronchoalveolar lavage fluid, ovalbumin-specific IgE and Th2-specific cytokines, IL-4, -5, and -13, were reduced with trifuhalol A treatment. In addition, IL-1β, IL-6, and TNF-α concentrations in lung homogenate were also significantly reduced via trifuhalol A treatment. Taken together, trifuhalol A, isolated from AC, was able to protect lung and airways from Th2-specific cytokine release, and IgE mediated allergic inflammation as well as the attenuation of IL-1β, IL-6, and TNF-α in lung, which results in the suppression of eosinophils and the mast cells involved asthmatic pathology.

Antioxidant and Anti-Inflammatory Effects of Agarum cribrosum Extract and Its Fractions in LPS-Induced RAW 264.7 Macrophages

Excessive oxidative stress and chronic inflammation are implicated in the pathogenesis of chronic inflammation diseases. The purpose of this study was to determine whether the antioxidant and anti-inflammatory effects of Busan-grown Agarum cribrosum ethanol extract (ACE) and its organic solvent five fractions are exhibited in lipopolysaccharide (LPS)-stimulated RAW 264.7 macrophages. ACE and its five fractions from ACE evaluated the total antioxidant activity and the effect of pro-inflammatory cytokines and antioxidant genes expression in LPS-induced RAW 264.7 macrophages. ACE and its ethyl acetate (EtOAc) fraction showed a high total phenolic content and total antioxidant capacity by decreasing free radicals scavenging activity. ACE and its EtOAc fraction significantly repressed LPS-induced tumor necrosis factor α and interleukin-1β gene expression. Additionally, ACE and its EtOAc fraction significantly diminished the LPS-stimulated gene expression of inducible nitric oxide synthase and cyclooxygenase 2 genes with a concomitant decrease in their protein levels in the macrophages. The gene expression of NADPH oxidase 2 was significantly abolished by ACE and its EtOAc fraction in LPS-induced macrophages, while other antioxidant genes showed minimal effects. The results suggest that ACE and its EtOAc fraction exert inhibitory effects on LPS-stimulated inflammation and oxidative stress in macrophages accompanied by total antioxidant activity.

Trifuhalol A, a phlorotannin from the brown algae Agarum cribrosum, reduces adipogenesis of human primary adipocytes through Wnt/β-catenin and AMPK-dependent pathways

Trifuhalol A, a fucol-type phlorotannin, was extracted and identified from the brown algae Agarum cribrosum. The total yield and purity of trifuhalol A from A. cribrosum were 0.98% and 86%, respectively. Trifuhalol A at 22 and 44 μM inhibited lipid accumulation in human primary adipocytes. Consistently trifuhalol A suppressed the expression of adipogenesis-related genes, such as proliferator-activated receptor-gamma (PPAR-γ), CCAAT/enhancer-binding protein-alpha (C/EBP-α), fatty acid synthase (FAS), and sterol regulatory element-binding protein-1 (SREBP-1), in a dose-dependent manner. Trifuhalol A increased the level of proteins such as wingless/integrated (Wnt)10b, nuclear-β-catenin, total-β-catenin, phospho-AMP-activated protein kinase (pAMPK), and phospho-liver kinase B1 (pLKB1) as well as the expression of genes such as Wnt10b, Frizzled 1, and low-density lipoprotein receptor-related protein 6 (LRP6). Additionally, trifuhalol A decreased the expression of the glycogen synthase kinase-3beta (GSK3β) gene. These results suggest that trifuhalol A reduces fat accumulation in human adipocytes via the Wnt/β-catenin- and AMPK-dependent pathways.

Anti-Inflammatory Activity of the Phlorotannin Trifuhalol A Using LPS-Stimulated RAW264.7 Cells Through NF-κB and MAPK Main Signaling Pathways

Trifuhalol A, a phlorotannin, was extracted from Agarum cribrosum with ethyl acetate and fractionated using Sephadex LH-20 column chromatography (SF1-SF6). The ethyl acetate fraction (EAF) and SF5-containing trifuhalol A exhibited strong inhibitory activity against hyaluronidase. The anti-inflammatory activity of the phlorotannin, EAF, and SF5 was determined through the inhibition of nitric oxide (NO) production in lipopolysaccharide-stimulated RAW264.7 cells. Furthermore, the inhibition of NO production was validated by confirming the appreciable downregulation of inducible nitric oxide synthase expression. Agarum cribrosum phlorotannin also markedly suppressed the expression of cyclooxygenase-2, interleukin (IL)-1β, IL-6, and tumor necrosis factor-α. In addition, the anti-inflammatory action was verified by examining its effects on proinflammatory signaling pathways. The activation of nuclear factor (NF)-κB and mitogen-activated protein kinases (MAPKs) was attenuated via the inhibition of NF-κB p-65, c-Jun N-terminal kinase, extracellular signal-regulated kinase 1/2, and p38 MAPK phosphorylation. Therefore, trifuhalol A is a potential source for either the prevention or the treatment of inflammation.

Antioxidant and Cosmeceutical Activities of Agarum cribrosum Phlorotannin Extracted by Ultrasound Treatment

An ultrasonic process for the effective extraction of phlorotannins from Agarum cribrosum with high total phlorotannin content (TPC) was optimized using response surface methodology (RSM). Optimal conditions for ultrasound extraction consisted of temperature: 30°C; time: 5.75 h; ratio of solvent to solid: 35 mL/g, where the TPC was 19.59 mg PGE/g. The crude extract was further partitioned using hexane, dichloromethane, ethyl acetate (EtOAc), and water, in that order. The EtOAc fraction with the highest TPC exhibited the strongest radical-scavenging activity against DPPH, ABTS, hydrogen peroxide, and reducing power, which was similar to that of ascorbic acid. Furthermore, the IC50 values of the EtOAc fraction against collagenase, elastase, and tyrosinase inhibitory activity were 29.63, 16.13, and 6.17 μg/mL, respectively, whereas epigallocatechin gallate (EGCG), EGCG, and kojic acid, the counterpart positive controls, were 68.90, 23.34, and 43.29 μg/mL, respectively. The EtOAc fraction was further fractionated using Sephadex LH-20 column chromatography, which yielded two major and four minor subfractions. The structure of the SF5 and SF6 subfractions were further determined through HPLC-DAD-QMS analyses and 1H and 13C NMR, in which only trifuhalol A was identified. The SF5 and SF6 subfractions exhibited significantly higher radical-scavenging activity against DPPH and reducing power than the EtOAc fraction, but no statistically significant differences were detected for ABTS, hydrogen peroxide, collagenase, elastase, and tyrosinase inhibitory activity. Based on the results, we propose that A. cribrosum phlorotannins could be a good source for natural antioxidants and cosmeceutical.

Molecular characterization and immunomodulatory activity of sulfated fucans from Agarum cribrosum

The sulfated-fucans, known as fucoidans, were isolated from Agarum cribrosum and fractionated using ion-exchange chromatography to determine their molecular characteristics and in vitro immunomodulatory activity. The crude and fractionated fucoidans (F1 and F2) consisted mostly of carbohydrates (52.4–56.0%), sulfates (12.7–23.0%) and uronic acid (14.1–21.8%), with a small amount of proteins (3.9–9.3%), and included various levels of fucose (44.0–46.7%), mannose (18.9–26.8%), galactose (16.8–33.0%), xylose (10.7–17.0%) and glucose (3.5–9.5%). The crude and fractionated fucans contained one or two subfractions with average molecular weights (Mw) ranging from 110.1×103 to 2420×103g/mol. The fractionated fucoidan, especially the F1 fraction, strongly stimulated murine macrophages (Raw 264.7 cells), producing a considerable amount of nitric oxide (NO) and inducing expression of inducible NO synthase (iNOS), cyclooxygenase-2 (COX-2) and interleukin-10 (IL-10) transcripts by activation of nuclear factor-kappa B (NF-κB) and mitogen-activated protein kinases (MAPKs) pathways. The maximally immunoenhancing F1 fraction was mainly composed of (1→3)-linked fucose, (1→2)-linked mannose and (1→4)-linked glucuronic acid with sulfates at C-2 or both the C-2 and C-4 positions in (1→2,3)- and (1→2,3,4)-linked fucose residues.

LPS-induced NO inhibition and antioxidant activities of ethanol extracts and their solvent partitioned fractions from four brown seaweeds

The nitric oxide inhibitory (NOI) and antioxidant (ABTS and DPPH radical scavenging effects with reducing power) activities of the ethanol (EtOH) extracts and solvent partitioned fractions from Scytosiphon lomentaria, Chorda filum, Agarum cribrosum, and Desmarestia viridis were investigated, and the correlation between biological activity and total phenolic (TP) and phlorotannin (TPT) content was determined by PCA analysis. The yield of EtOH extracts from four brown seaweeds ranged from 2.6 to 6.6% with the highest yield from D. viridis, and the predominant compounds in their solvent partitioned fractions had medium and/or less polarity. The TP and TPT content of the EtOH extracts were in the ranges of 25.0–44.1 mg GAE/g sample and 0.2–4.6 mg PG/g sample, respectively, which were mostly included in the organic solvent partitioned fractions. Strong NOI activity was observed in the EtOH extracts and their solvent partitioned fractions from D. viridis and C. filum. In addition, the EtOH extract and its solvent partitioned fractions of D. viridis exhibited little cytotoxicity to Raw 264.7 cells. The most potent ABTS and DPPH radical scavenging capacity was shown in the EtOH extracts and their solvent partitioned fractions from S. lomentaria and C. filum, and both also exhibited strong reducing ability. In the PCA analysis the content of TPT had a good correlation with DPPH (r = 0.62), ABTS (r = 0.69) and reducing power (r = 0.65), however, an unfair correlation was observed between the contents of TP and TPT and NOI, suggesting that the phlorotannins might be responsible for the DPPH and ABTS radical scavenging activities.

구멍쇠 미역 에탄올 추출물의 섭취가 비만유도 흰쥐의 지질농도에 미치는 영향

고지방식이로 비만 및 고지혈이 유발된 실험동물에서 체중, 혈중지질, 혈청생화학적 검사 및 장기무게를 측정하여 구멍쇠 미역 추출물 투여로 인한 혈중지질 개선효과와 구멍쇠 미역 추출물의 간과 신장의 기능 및 장기무게에 미치는 영향에 대해 조사하였다. 체중 및 사료이용효율은 고지방식이에 의해 고지방군에서 증가현상을 보였으며, 구멍쇠 미역 추출물 5 %와 10 % 투여군인 HF5S과 HF10S군에서 구멍쇠 미역 추출물 투여로 인한 체중증가량 감소와 식이효율 감소현상을 보였다. 혈청 생화학적 검사에서 고지방식이에 의해 혈중 ALT, AST의 증가가 관찰되었으나 구멍쇠 미역 추출물 투여에 의해 기본식이군과 비슷한 수준으로 유지되는 것을 볼 수 있었다. 혈중 creatinine은 고지방식이 및 구멍쇠 미역 추출물 투여에 영향을 받지 않았으나 g-GT의 경우 구멍쇠미역 추출물을 10 % 첨가하였을 때는 유의적으로 감소하여 기본식이군과 고지방식이군보다 낮아졌다. 혈중지질 변화는 총 콜레스테롤, LDL-콜레스테롤, triglyceride, 동맥경화지수(AI) 모두 고지방식이에 의해 유의적인 증가현상을 보였으며, 구멍쇠 미역추출물 투여한 경우 고지방식이군에 비하여 총콜레스테롤과 LDL-콜레스테롤은 감소하였으나 동맥경화지수는 변화가 없었다. 이상의 실험결과 구멍쇠 미역 추출물은 비만유도 흰쥐에서 체중과 간의 무게 감소와 더불어 혈청의 지질성상의 개선에 긍정적인 영향을 미치는 것으로 나타났다. 이러한 결과는 구멍쇠 미역에 함유된 다량의 식이섬유소와 미네랄 등의 생리활성 물질이 지질대사를 개선시키고 지방 축적을 억제하여 비만, 고지혈증, 이상지혈증의 예방 및 개선 효과를 나타낼 것으로 기대되며 나아가 심혈관계 질환의 예방 및 치료에 긍정적인 효과가 있을 것으로 사료된다. This research was performed to investigate the effect of Agarum cribrosum ethanol extracts on the levels of lipids in the serum of rats fed a high-fat diet for 10 weeks. Experimental groups were divided into basal diet only (BDG), high fat diet control (HFDCG), high-fat diet and 5% Agarum cribrosum ethanol extract powder (HF5S), and high-fat diet and 10% Agarum cribrosum ethanol extract powder(HF10S) groups. The levels of hematological variables were not significantly different among the four groups. Compared with the control group's serum total cholesterol level of 89.14 mg/dL, the levels of the HF5S and HF10S groups were significantly lowered to 77.26 and 75.47 mg/dL, respectively. Compared with the control group's LDL-cholesterol leve of 27.41 mg/dL, the LDL-cholesterol levels of the HF5S and HF10S groups were significantly lowered to 20.64 and 20.17 mg/dL, respectively. Also, compared to the control group's serum triglyceride level of 98.36 mg/dL, the triglyceride levels of the HF5S and HF10S groups were significantly lowered to 87.94 and 87.39 mg/dL, respectively. These results indicate that dietary intake of Agarum cribrosum ethanol extracts might have beneficial effects on obesity by reducing body weight and improving blood lipid profile.

구멍쇠 미역의 변비 완화 효과 및 혈액지방에 미치는 영향

The present study was conducted to evaluate the effects of Agarum cribrosum on weight change and defecation states in rats with constipation induced by loperamide. Food intake and body weight both decreased in the 5% Agarum cribrosum and loperamide-treated group (SD5) and 10% Agarum cribrosum and loperamide-treated group (SD10), whereas fecal water contents increased by 1.6 and 2.1-fold in the SD5 and SD10 groups, respectively. The concentrations of total-cholesterol, HDL-cholesterol and triglyceride in the sera of the SD5 and SD10 groups were lower than those in the control (C) group. However, the biochemical parameters, GOT (glutamic oxaloacetic transaminase), GPT (glutamic pyruvic transaminase), and glucose levels, were not affected by the level of Agarum cribrosum. In addition, the concentrations of total-cholesterol and triglyceride in the livers of the SD5 and SD10 groups were also lower than those in the control group. The results of the present study demonstrated that Agarum cribrosum might ameliorate constipation symptoms, and lower lipid concentrations in the blood and liver.

구멍쇠미역의 식품영양학적 접근 및 생리활성 분석

본 연구는 구멍쇠미역을 대상으로 건강기능성식품의 소재로의 활용을 위한 가능성을 타진하고자 영양성분 분석을 통한 식품영양학적 접근 및 생리활성 기능을 분석하였다. 식품 영양학적 접근에서의 구멍쇠미역의 일반성분은 건량 기준으로 당질 45.4%, 조단백질 15.0%, 조지방 2.3% 및 조회분 33.1%이었고, 구멍쇠미역 100 g의 함유 열량은 262.3 kcal로 분석되었으며, 총 식이섬유소 함량은 34.0%로 나타났다. 또한, 총 18종의 아미노산으로 구성되었으며, 그 함량은 12,402.42 mg이었고, 무기질 중 칼륨의 함유량이 가장 높았고, 그 다음이 칼슘, 나트륨, 마그네슘 순으로 나타나, 알칼리성 재료임을 알 수 있었다. 구멍쇠미역 추출물의 총 페놀 함량 및 총 플라보노이드 함량분석 결과, 각각 <TEX>$34.1{\pm}2.56mg/g$</TEX>과 <TEX>$4.9{\pm}0.26mg/g$</TEX>으로 나타났다. 다양한 항산화 평가 모델(DPPH, FRAP, 환원력, ABTS)을 통하여 구멍쇠미역 추출물의 항산화 활성을 측정한 결과, 구멍쇠미역 추출물의 농도가 증가함에 따라 항산화능이 유의적으로 증가하는 것으로 나타났다. 이상의 결과로부터 구멍쇠미역은 식품으로서의 이용가치가 매우 크며, 구멍쇠미역 추출물은 항산화능이 있음을 확인할 수 있었다. The purpose of this study is to determine the possibility of using Agarum cribrosum as a natural health food source. To accomplish this purpose, the contents of the general and antioxidant activities of Agarum cribrosum were measured. The contents of carbohydrate, crude protein, crude lipid and ash were 45.4%, 15.0%, 2.3% and 33.1%. The calories of Agarum cribrosum were 262.3 kcal and total dietary fiber of Agarum cribrosum was 34.0%. The protein contained a total of 18 different kinds of amino acids. The content of amino acids was 12,402.42 mg/100 g. The K was the largest mineral followed by Ca, Na and Mg, implying that Agarum cribrosum is an alkali material. The antioxidant activity of Agarum cribrosum was assessed by various radical scavenging assays using DPPH (2,2-diphenyl-1-picrylhydrazyl), FRAP (ferric ion reducing antioxidant power), reducing power, and ABTS (2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid)). All antioxidant activity of Agarum cribrosum extract increased the concentration of the dependents. Total phenolic contents of Agarum cribrosum extract were <TEX>$34.1{\pm}2.56mg/g$</TEX>, and total flavonoids contents were estimated at <TEX>$4.9{\pm}0.26mg/g$</TEX>. General nutrients and other antioxidant bioactive materials in Agarum cribrosum were also potential materials for good health food. It is expected that a follow-up study of Agarum cribrosum through developing processed food and evaluation of their functional properties would provide useful information or sources of functional foods.

Oxidative Stress and Antioxidant Activities of Intertidal Macroalgae in Korea

The oxidative stress level and antioxidant activities in two green algae (Ulva pertusa and Ulva linza), two brown algae (Agarum cribrosum and Dictyota dichotoma), and three red algae (Grateloupia lanceolata, Carpopeltis affinis, and Gracilaria verrucosa) collected from intertidal regions of Korea were assessed. In the two green algae, although the total glutathione content was not as high as that of the brown algae, the glutathione pool was extremely reduced, and the glutathione reductase (GRd)/glutathione peroxidase (GPx) activity ratio was high, which apparently plays an important role for protection against oxidative damage, as manifested by low lipid peroxidation. In the brown algae, which exhibited a low lipid peroxidation level that was comparable to the green algal species, the highest glutathione content, together with high GPx activity, appears to be the most important factor in their antioxidant protection. The red algal species exhibited extremely high lipid peroxidation levels. They also contained the lowest and most oxidized glutathione among the species, as well as the lowest GRd activity. In spite of the marked difference in the glutathione content, the significant difference in the activity of γ-glutamylcysteine ligase, the rate limiting enzyme for glutathione synthesis, among the species was not exhibited. Our results suggest that there is a significant difference in the levels of oxidative stress and antioxidant capacity among the algal species, and that the glutathione system, especially the efficiency of glutathione recycling, plays a vital role in antioxidative protection in algal species.

해조류로부터 항고혈압성분의 분리정제

To isolate natural antihypertensive substances from edible seaweeds, we screened for and separated active compounds contained in natural Underia pinnatifida, cultural Underia pinnatifida, Laminaria japonica, Sporophylls and Agarum cribrosum. They were extracted using room temperature water, boiling water, acetone, and methanol in turn or using room temperature water, ether, acetone, methanol and boiling water in order. The in vitro antihypertensive activity was quantified as inhibitory efficacy against angiotensin-Ⅰ converting enzyme (ACE), which is a factor inducing hypertension. For all of the seaweeds tested, the fractions soluble in room temperature water and in boiling water showed the strongest ACE inhibitory effect among the extracted fractions. Conversely, the methanol-extracted fractions for all of the seaweeds tested showed no antihypertensive activity. While the ether and acetone fractions had slight antihypertensive effects. The compounds in the aqueous extracts that had antihypertensive activity were presumed to be polysaccharides, such as fucoidan and alginate.

Detection of deep water benthic macroalgae using image-based classification techniques on multibeam backscatter at Cashes Ledge, Gulf of Maine, USA

Benthic macroalgae form an important part of temperate marine ecosystems, exhibiting a complex three-dimensional character which represents a vital foraging and spawning ground for many juvenile fish species. In this research, image-based techniques for classification of multibeam backscatter are explored for the detection of benthic macroalgae at Cashes Ledge in the Gulf of Maine, USA. Two classifications were performed using QTC-Multiview, differentiated by application of a threshold filter, and macroalgal signatures were independently extracted from the raw sonar datagrams in Matlab. All classifications were validated by comparison with video ground-truth data. The unfiltered classification shows a high degree of complexity in the shallowest areas within the study site; the filtered demonstrates markedly less variation by depth. The unfiltered classification shows a positive agreement with the video ground-truth data; 82.6% of observations recording Laminaria sp., 39.1% of Agarum cribrosum and 100.0% ( n = 3) of mixed macroalgae occur within the same acoustically distinct group of classes. These are discrete from the 8.1% recorded agreement with absences and nulls (>40 m) of macrophytes ( n = 32) from a total of 86 ground-truth locations. The results of the water column data extraction ( WCDE) show similar success, accurately predicting 78.3% of Laminaria sp. and 30.4% of A. cribrosum observations. The unfiltered classes which showed agreement with the ground-truth data were then compared to the WCDE results. Comparison of surface areas reveals the overall percentage agreement is relatively constant with depth (67.0–70.0%), with Kappa coefficient increasing from k = 0.17–0.35 as depth (and surface area) increases. The results have demonstrated that both methods were more effective at detecting the presence of Laminaria sp. (82.6–77.3%) than Agarum cribrosum, (66.6–30.4%), and that the efficiency of prediction decreased with depth. Canopy volume derived from the WCDE analysis was between 1.21 × 10 6 m 3 at <24 m water depth, 1.82 × 10 6 m 3 at <30 m and 2.45 × 10 6 m 3 at <40 m. These results suggest that the presence of benthic macrophytes has a significant capacity to affect image-based classification of acoustic data, and highlights the fact that multibeam backscatter and image-based classification have significant potential for benthic macroalgal research. This is beneficial to help refine segmentations of substrates, adding valuable contextual information about biological characteristics of infaunal and epifaunal benthic communities.

강릉 연안의 해조군락과 유용 해조자원 분포

An intertidal marine benthic algal vegetation and vertical distribution at Kangnung and it’s vicinity, the eastern coast of Korea was investigated to clarify the community structure and vertical distribution by quadrat method. Marine algae identified from the area were 116 species; 15 green, 31 brown and 70 red algae. The dominant species were Ulva pertusa, Codium fragile, Undaria pinnatifida, Dictyota dichotoma, Gelidium amansii, Corallina pilulifera, Carpopeltis affinis, Grateloupia filicina, Pachymeniopsis elliptica and Chondrus ocellatus at study sites. The vertical distribution of intertidal marine algae was divided into three distinct zones. They were characterized by Porphyra tenera at the upper, Enteromorpha spp. and Ulva pertusa at the middle, and Sargassum thunbergii, Hizikia fusiformis and Pachymeniopsis elliptica at the lower zones, respectively. The vertical distribution of subtidal zone algae were characterized by Laminaria spp. at 15m depth and Kjellmaniella crassifolia at 15 to 25 m depths, whereas Agarum cribrosum was dominant at the lower zone than 25 m depth.

Temporal variation in community interfaces: kelp-bed boundary dynamics adjacent to persistent urchin barrens

We examined, over 2 years, factors affecting the temporal stability of the lower limit of kelp beds (Alaria esculenta) at five subtidal sites in the Mingan Islands, northern Gulf of St. Lawrence. The position of the lower limit of the beds varied markedly among sites and over time and was largely controlled by the green sea urchin, Strongylocentrotus droebachiensis, which formed dense (up to 500 individuals m−2) feeding fronts at the lower edge of the beds. These aggregations advanced over the kelp most rapidly during the summer (at rates as high as 2.5 m month−1), and there appeared to be a threshold urchin biomass of ~5 kg m−2 below which the fronts could not substantially reduce the limit of the beds. The fronts consisted mainly of large individuals, whereas smaller urchins predominated in the barrens zone below the kelp beds. At one site, we recorded large seasonal shifts in overall urchin densities, with large increases and decreases during the summer and winter, respectively. An urchin exclusion experiment indicated that algal recruitment in the barrens was two orders of magnitude greater in the absence than in the presence of urchins. The kelp Agarum cribrosum greatly restricted urchin movements, and the greater temporal stability of the kelp bed at one site appeared related to the gradual replacement of Alaria esculenta in the lower kelp bed by a large stand of Agarum cribrosum. We propose that perturbations by abiotic factors (e.g., ice scouring and water motion) trigger important but localized changes in urchin densities that, in turn, largely determine the limits of kelp bed distribution in this region of the Atlantic where urchin barrens are a persistent community state.

Macroalgal canopies: distribution and diversity of associated invertebrates and effects on the recruitment and growth of mussels

We examined the invertebrate assemblages associated with macroalgal canopies in the Mingan Islands (northern Gulf of St. Lawrence, eastern Canada) in the summer and fall of 2001. Invertebrates were sampled in patches or beds of 4 species of macroalgae (Alaria esculenta, Agarum cribrosum, Desmarestia viridis and Ptilota serrata) as well as in adjacent urchin barrens. Multivariate analyses of the invertebrates on the algal fronds, those on the underlying substratum, and the 2g roups together demonstrated differences in invertebrate assemblages among all 5 habitats. A. esculenta sheltered the most distinct invertebrate community due to the domination of the sub- stratum under this alga by the blue mussel Mytilus edulis. Differences among other canopy types were due to differences in invertebrate assemblages both on the algal fronds and on the substratum. A manipulative experiment involving the removal of the canopy of the 2 most abundant macroalgae, A. esculenta and A. cribrosum, was carried out to examine their effects on mussels. Recruitment of mussels onto ceramic tiles varied among treatments and was greatest in the A. esculenta zone with greater, but non-significant, recruitment under the canopy. The growth of mussels from early July to October was higher in the A. cribrosum zone than the A. esculenta zone. However, there was no effect of the algal canopy in either zone. Our study demonstrates that the local diversity and distri- bution of benthic invertebrates is intimately associated with macroalgae, and reinforces the need for detailed sampling and analyses for assessing distributional patterns.

Algal colonization in urchin barrens: defense by association during recruitment of the brown alga Agarum cribrosum

We investigated the process whereby juveniles of the kelp Agarum cribrosum escape grazing by the green sea urchin, Strongylocentrotus droebachiensis, on urchin barrens in the rocky subtidal zone in the Mingan Islands, northern Gulf of St. Lawrence. The highest recruitment of juvenile A. cribrosum occurred under the canopy of the large filamentous phaeophyte Desmarestia viridis, where urchin densities were markedly reduced, compared to the surrounding area. This pattern of distribution appeared to be related to the wave-induced sweeping motion of D. viridis, although currents may modify the back and forth motion of the alga by pushing the canopy towards a specific direction, thereby allowing urchins to invade the non-swept areas. The density of juveniles under D. viridis plants increased with plant size and increasing proximity to the holdfast. Living under D. viridis slightly reduced the growth rate of the A. cribrosum juveniles, but this loss in growth was clearly outweighed by the gain in protection from sea urchin grazing. The time scale over which D. viridis provides protection is in the order of months, as D. viridis is an annual alga that disappears in early autumn. This defensive association of juvenile A. cribrosum with D. viridis is possibly a successional step leading to the formation of mature stands of A. cribrosum.

The Distribution of Nearshore Fishes in Kelp and Eelgrass Communities in Prince William Sound, Alaska: Associations with Vegetation and Physical Habitat Characteristics

The nearshore (less than 20 m depth) demersal fish community in Prince William Sound, Alaska, is dominated by Pacific cod, Gadus macrocephalus, pricklebacks (mostly Arctic shanny Stichaeus punctatus), gunnels (mostly crescent gunnels Pholis laeta), a variety of greenlings (Hexagrammidae) and sculpins (Cottidae). During summer, the spatial distribution of fishes, over scales of 100's of m to 10's of km, varied by habitats characterized by different vegetation types. Juvenile Pacific cod and greenlings were numerically dominant in eelgrass, Zostera marina, beds. Pricklebacks and sculpins were dominant in areas with an understory of the kelps Agarum cribrosum and Laminaria saccharina. Greenlings and sculpins were the most abundant demersal fishes in more exposed sites with a canopy of Nereocystis luetkeana and an understory of L. bongardiana. Measured habitat variables, including vegetation type, slope, vegetation biomass, and substratum type, explained a significant proportion of the variation in the presence or absence of most fishes. The relative importance of different habitat characteristics varied between taxonomic groups of fishes. Vegetation type explained a significant proportion of variation for cod, rockfishes, and ronquils. Juvenile cod were closely associated with eelgrass, while rockfish and ronquils were associated with kelps. Pricklebacks and rockfishes were more frequently observed on steeply sloped shorelines, while ronquils were more often found at sites with higher biomass of vegetation. Within A. cribrosum habitats, more greenlings and sculpins were present at sites where algal biomass was higher. Also, sculpins were more abundant in deeper water and gunnels were more abundant in shallow water within this habitat. These associations may not have been causative. However, evidence suggests that some differences between fish communities in eelgrass and Agarum beds may have been causally related to vegetation characteristics. The possible roles of different vegetation types as refugia from predators or as sources of prey are discussed.

Fatty acids of brown algae from the Russian far east

Twenty species of brown algae belonging to the Chordariales, Ralfsiales, Dictyosiphonales, Scytosiphonales, Desmarestiales, Laminariales and Fucales orders were investigated for their fatty acid composition by capillary gas chromatography. Polyunsaturated fatty acids (PUFAs) with 18 and 20 carbon atoms, palmitic and oleic acids were major components. No correlation between the taxonomic position of the brown algal species and the distribution of these acids was found. Peculiarities of fatty acid composition were shown for members of the Fucaceae only, which contained the highest percentages of 14:0 and 18:1(n–9), the lowest amounts of (n–3) PUFAs and had a C 20 non-methylene interrupted acid. Agarum cribrosum had fatty acid patterns unique for the Phaeophyta. The occurrence of the rare C 16 PUFAs, 18:2(n–4) and a high content of 22:5(n–3) were a characteristic feature of this alga. Fatty acid composition of brown algae depends on different factors and the extent of their influence is species-specific.

Daylength range for circannual rhythmicity in Pterygophora californica (Alariaceae, Phaeophyta) and synchronization of seasonal growth by daylength cycles in several other brown algae

The growth rhythm of the kelp Pterygophora californica Ruprecht could be synchronized to periods of 3 months by daylength cycles of sinusoidal or rectangular shape. Arhythmic, continuous growth was found at 8 and 9 h light per day, while rhythmic and synchronized growth cycles with short resting phases occurred during periodic daylength shifts from 8 upward to 10, 12, 14 or 16 h light per day, or from 16 downward to 12 or 10 h light per day. Cultivation at constant 10, 12, 14 or 16 h light per day permitted free-running growth rhythms. These results suggest that a critical daylength at 8-9 h light per day sets a lower limit to circannual rhythmicity in P. californica and is at the same time used by the alga as a strong Zeitgeber signal for synchronizing the circannual growth rhythm to the natural year. The growth rhythms of Agarum cribrosum (Mertens) Bory, Pleurophycus gardneri Setchell et Saunders, Laminaria saccharina (Linnaeus) Lamouroux, L. bongardiana Postels et Ruprecht (= L. groenlandica Rosenvinge sensu Druehl 1968) and Desmarestia aculeata (Linnaeus) Lamouroux could be synchronized by artificial daylength cycles, but proof of free-running, circannual growth rhythms is still lacking for these species.