Cystoseira Myrica Research Articles

Potential of green/brown algae for monitoring of metal(loid)s pollution in the coastal seawater and sediments of the Persian Gulf: ecological and health risk assessment.

The current investigation evaluates metal (loid)s biomonitoring using algae as well as the metal(loid) pollution of seawaters and sediments in the northern part along the Persian Gulf. Algae, seawater, and sediment samples were collected from four coastal areas with different land applications. The concentration of Ni, V, As, and Cd in abiotic samples (seawater and sediment) and four species of algae (Enteromorpha intestinalis, Rhizoclonium riparium, Cystoseira myrica, and Sargassum boveanum) was measured using an ICP-AES device. Concentrations of potentially toxic elements in seawater, sediments, and algae species followed the trend of "Ni˃V˃As˃Cd." The area of Asaloyeh (with the highest industrial activity) and the Dayyer area (with the lowest industrial activity) provided the highest and lowest amounts of metal(loid)s pollution, respectively. The average concentrations of V and As in four algae species significantly differed for all sampled areas. Obtaining the bio-concentration factor (BCF) > 1 for seawater and < 1 for sediment indicated that the studied algae have the ability to efficiently concentrate metal(loid)s from seawater and the limited accumulation of metals in sediments. According to the Nemerow pollution index, the order of metal(loid)s pollution for the studied areas estimated as Asaloyeh>Ganaveh>Bushehr>Dayyer. Algae species of C. myrica and E. intestinalis can often serve as suitable biological tools for monitoring seawater and sediment quality.

Molecular Identification, Characterization and Antioxidant Activities of Some Bacteria Associated with Algae in the Red Sea of Jeddah.

Algae-associated bacteria produce secondary metabolites that have a great biological impact. The aim of this study was isolation, identification and evaluation the antioxidant activities of the associated bacteria of seven algae, Padina pavonica, Dictyota dichotoma, Cystoseira myrica, Halimeda opuntia, Ulva lactuca, Digenea simplex and Jania sp. The bacteria were isolated, characterized and identified. Identification was carried out using 16S rRNA gene sequencing. The identified bacteria were belonging to 6 families, Alteromonadaceae, Bacillaceae, Lactobacillaceae, Pseudomonadaceae, Rhodobacteraceae and Vibrionaceae and 9 genera. The identified bacteria were belonging to genera, Alteromonas, Bacillus, Lysinibacillus Vibrio, Lactobacillus, Paracoccus, Leisingera, Pseudomonas and Pseudovibrio. The antioxidant activities of the bacterial ethyl acetate extracts was examined by scavenging DPPH (2,2-diphenyl-1-picrylhydrazyl) and FRAP (Ferric Reducing Antioxidant Power) methods. Out of the 17 isolated bacteria, Lactobacillus plantarum showed 95.7% free radical scavenging with EC50 = 17.7 μg mL-1, which is nearly similar to the positive control (Butylated Hydroxytoluene, BHT). The FRAP value of Lactobacillus extract was 2.00 mM ferric equivalent/mg of the extract. Phytochemical analysis of the bacterial extract revealed the presence of some secondary metabolites such as steroids, saponins, tannins, flavonoids, anthocyanin and betacyanin in all tested extracts. The Red Sea algal associated bacteria have a great antioxidant potential that can be used in pharmaceutical industries.

Anti-microbial and Anti-diabetic Activity of Six Seaweeds Collected from the Red Sea, Egypt

Marine algae are a well-known source of active compounds with many biological activities. Many studieshad point to the anti-microbial and anti-diabetic activity of seaweeds. Egyptian shores are rich withseaweeds, yet studies concerning their biological activity are inadequate. In the present work, the 80%methanolic extract of six seaweeds (Actinotrichia fragilis, Cystoseira myrica, Hormophysa cuneiformis,Laurencia papillosa, Sargassum cinereum, and Turbinaria turbinate) were tested for their antimicrobialactivity using disc diffusion method and anti-diabetic activity using the Inhibition of α-glucosidasemethod. The six species were collected from Hurghada, Red Sea, Egypt during late December, 2012. Theresults should that the algal extracts were effective against both Gram-positive and Gram-negative bacteriawhen used at 2000μg/disc concentration. On Candida albicuns, both low and high concentrations showedactivity. For anti-diabetic activity, H. cuneiformis was the most active species that reached to 53%inhibition of α-glucosidase at the highest concentration (1000 μg/ml) with IC50 676.9 μg/ml. Inconclusion, the tested seaweeds possess a good anti-microbial and anti-diabetic activity, especially thespecies Hormophysa cuneiformis.

Anti-microbial and Anti-diabetic Activity of Six Seaweeds Collected from the Red Sea, Egypt

Marine algae are a well-known source of active compounds with many biological activities. Many studieshad point to the anti-microbial and anti-diabetic activity of seaweeds. Egyptian shores are rich withseaweeds, yet studies concerning their biological activity are inadequate. In the present work, the 80%methanolic extract of six seaweeds (Actinotrichia fragilis, Cystoseira myrica, Hormophysa cuneiformis,Laurencia papillosa, Sargassum cinereum, and Turbinaria turbinate) were tested for their antimicrobialactivity using disc diffusion method and anti-diabetic activity using the Inhibition of α-glucosidasemethod. The six species were collected from Hurghada, Red Sea, Egypt during late December, 2012. Theresults should that the algal extracts were effective against both Gram-positive and Gram-negative bacteriawhen used at 2000μg/disc concentration. On Candida albicuns, both low and high concentrations showedactivity. For anti-diabetic activity, H. cuneiformis was the most active species that reached to 53%inhibition of α-glucosidase at the highest concentration (1000 μg/ml) with IC50 676.9 μg/ml. Inconclusion, the tested seaweeds possess a good anti-microbial and anti-diabetic activity, especially thespecies Hormophysa cuneiformis.

Extraction of Sulphated Polysaccharides (SPs) from Different Species of Marine Macroalgae and Studying their Role as Natural Anticoagulant

Marine algae are the most important source of non-animal sulphated polysaccharides which possess important pharmacological activities such as anticoagulant, antioxidant, anti-inflammatory, antiviral, antibacterial agents. Therefore, marine algae derived sulphated polysaccharides have great potential to be further developed as medicinal products. Marine macroalgae were collected seasonally for one year (September 2013 to August 2014) from the intertidal zone of site I: Ras El-Adabiya whichlocated on the western shore of Suez Bay and site II: Ras Sedr which located north–east of the Gulf of Suez. The purpose of this study was to extract sulphated polysaccharides from marine macroalgae (Ulva lactuca, Codium dwarkense, Hypnea cornuta, Hormophysa triquetra, Sargassum denticulatum and Cystoseira myrica) by two different methods (hot and cold water extracts) and chemical analysis also done ( protein content, total sugar , sulphate content , sulfer and nitrogen and uronic acid). The results of thephysico-chemical parameters for sea water samples showed that temp ranged between 15-30 °C, pH 7.8-8.7, salinity 38-42 ‰ , DO 6-7 mg/L, NO3 0.021-4.6 mg/L,NO2 0.004 -0.032 mg/L, NH4 0.019-0.3mg/L and PO4 0.005-0.015 mg/L. The potential of use sulphated polysaccharides as natural anticoagulant was tested by the activated partial thromboplastin time (APTT) and the prothrombin time (PT) tests. The results showed that higher blood anticoagulant activity of SPs is proportional to the carbohydrate and sulphate contents and inversely proportional to the protein and uronic acid contents. So, The significant highest value of prothrombin time was 26.50±0.10 sec at conc. of 20% SPs cold extract from the brown alga Hormophysa triquetra, while the lowest value was 1.13±0.06 sec at conc. of 5% SPs hot extract of the red alga Hypnea cornuta. Also, the results indicated that the highest value of activated partial thromboplastintime 42.20±0.10 sec was recorded atconc. of 20% SPs cold extract from the brown alga Hormophysa triquetra, On the other hand, the lowest value 5.63±0.25 sec was recorded at conc. of 5% SPs hot extract from the red alga Hypnea cornuta .

Antiviral Activities and Phytochemical Constituents of Egyptian Marine Seaweeds (Cystoseira Myrica (S.G. Gmelin) C. Agardh and Ulva Lactuca Linnaeus) Aqueous Extract

Background: some natural and synthetic compounds can prevent, suppress, or reverse the progression of virus infection. Natural products have proven to be the most effective in terms of their ability to act as an antiviral. In the present study, the antiviral potentiality of the bioactive compounds derived from aqueous extract of two Egyptian marine seaweed species (Cystoseiramyrica and Ulva lactuca)were assessed on different viruses. Materials and methods:these two species were collected from Hurghada at the Red Sea and Al-Agami area in Alexandria Mediterranean Sea, Egypt.The assay of cytotoxicity and antiviral activity by MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenlytetrezolium bromide] and by neutralization methods were conducted. Results:these two species have a bioactive compound affected hepatitis A virus (HAV-H10), Coxsackie B4 virus,herpes simplex virus types-1 (HSV-1) and type2 (HSV-2), grow and cytopathic effect (CPE) in Vero cells.

Nematicidal properties of some algal aqueous extracts against root-knot nematode, Meloidogyne incognita in vitro

The effectiveness of aqueous extracts derived from nine algal species atdifferent concentrations on egg hatching and mortality of Meloidogyne incognita(Kofoid and White) Chitwood juveniles after various exposure times weredetermined in vitro. Results indicated that Enteromorpha flexuosa at theconcentration of 80% was the best treatment for suppressing the egg hatching withvalue of 2 % after 5 days of exposure, followed by Dilsea carnosa extract (3%) andCodium fragile (4%) at the same concentration and exposure time. Likewise,application of C. fragile, D. carnosa , E. flexuosa and Cystoseira myrica extracts atthe concentrations of 80 and 60% were highly toxic to the nematodes, killing morethan 90 % of nematode larva after 72 hours of exposure while the others gave quitelow mortalities. The characteristic appearances in shape of the nematodes killed byC. fragile, D. carnosa , C. myrica, E. flexuosa and Sargassum muticum wassigmoid (Σ-shape) with some curved shape; whereas, the nematodes killed by otheralgal species mostly followed straight or bent shapes. The present study proved thatfour species of algae C. fragile, D. carnosa, C. myrica and E. flexuosa could beused for the bio-control of root-knot nematodes.

Biological activity and chemical constituents of red and brown algae from the persian gulf.

Different solvent extracts of a red algae, Hypnea flagelliformis, and two brown algae, Cystoseira myrica and Sargassum boveanum, which were collected from the Persian Gulf coast were subjected to different bioassays, including: 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical scavenging assay, antibacterial and antifungal activity by thin layer chromatography (TLC)-bioautography, agar disc diffusion (ADD) and nutrient-broth micro-dilution (NBMD) bioassays. The water extracts were found to have the most antioxidant activity. The antibacterial minimum inhibitory concentrations (MIC) of the active extracts were determined for the susceptible organisms, Staphylococcus aurous and Bacillus subtilis, using NBMD bioassays. The active substances were identified as free fatty acids (FFA), by using gas chromatography-mass spectrometry (GC-MS). After derivatization to their methyl esters, their concentrations were measured by using GC- lame ionization detection (GC-FID). In addition to the fatty acids, fucosterol, cholesterol and 22-dehydroxychlosterol were detected as the major sterols in S. boveanum extract using GC-MS analyses.

Diketopiperazine derivatives from Enterobacter cloacae isolated from the Red Sea alga Cystoseira myrica

AimThis study is an attempt to explore the biological activities of isolated endophytic bacteria from marine sources that were coded A1, A2, and A3 (Padina pavonica), A4 (Cystoseira myrica), A5 (Acanthophora dendroides), and A6 (Sargassum sabrepandum). The bacteria coded C1, C2, and C3 were isolated from the soft coral Nephthea mollis and S1 and S2 were isolates from the sponge Hymedesmia spp. The primary aim of the study was the identification of active compounds.Materials and methodsThe bioactive compounds were extracted using ethyl acetate from nutrient broth media; biological activities of the extracted metabolites and 16S rDNA identification of the most promising isolate were studied. The eight major fractions of the extract showed different composition patterns when identified by liquid chromatography/mass spectrometry analyses.Results and conclusionAgar diffusion assay showed inhibitory activities of A4 extracts against the growth of most pathogenic microorganisms. Identification using PCR 16S rDNA and electrophoresis confirmed 98% identity to the Enterobacter cloacae strain GH1 (ac: JF261136.1). Eight compounds out of fifteen in the extract were identified as diketopiperazine derivatives. The maximum growth of E. cloacae was obtained at 30°C, pH 7, with the addition of maltose and KI to the media. The free radical scavenging activity exhibited good antioxidant activity (72.19%, IC 50 = 1.266 mg/ml) on using 2.0 mg/ml of the crude extract. The extract showed a high antiviral activity towards Newcastle disease virus and avian influenza virus A(H5N1).

Inhibition of the development of pathogenic fungi by extracts of some marine algae from the red sea of Jeddah, Saudi Arabia

In this study, the predominant marine algae were collected from three different sites in the coastal area of Al-Kumrah at south of the Red sea of Jeddah, during summer and autumn 2009. The different marine algae belonged to Chlorophyta ( Enteromorpha prolifera and Ulva reticulata ), Phaeophyta ( Cystoseira myrica , Padina pavonica , Sargassum portieriatum and Turbinaria triquetra ) and Rhodophyta ( Gracilaria multipartita ). Algal extraction was achieved successively by using petroleum ether, diethyl ether, ethyl acetate and methanol. The algae extracts were tested in vitro for antifungal activity against Aspergillus flavus , Aspergillus fumigatus , Aspergillus niger and the yeast Candida albican s, by using agar-well diffusion method. The crude extracts of the tested algae revealed differences in their bioactivities. The maximum growth inhibition for fungi was recorded in ethyl acetate extract of T. triquetra against C. albicans (30 mm), methanol extract of E. prolifera (29 mm) and ethyl acetate extract of Padina pavonica (28 mm) against A. fumigatus . The results clarified that Chlorophyta and Phaeophyta exhibited the highest biological activity against the tested fungi, whereas the lowest was achieved in Rhodophyta. The minimal inhibitory concentrations (MICs) of the crude extracts of the tested algae ranged from 0.5 to 3.0 μg/ml. The results confirmed the potential of seaweed extracts as a natural source of antimicrobial compounds. The antifungal activity of different extracts of marine algae which belongs to Chlorophyta, Phaeophyta and Rhodophyta were examined against A. flavus , A. fumigatus , A. niger and the yeast C. albicans . The algae belonging to Chlorophyta and Phaeophyta exhibited the highest inhibitory effect against the test pathogenic fungi. The different extracts showed different activities against fungi. The antimicrobial activity depended on both algal species and the efficiency of solvents in the extraction of bioactive substances. Keywords: Green algae, brown algae, red algae, solvent extracts, antifungal activity, minimal inhibitory concentrations (MICs)

DNA SEQUENCE DATA DEMONSTRATE THE POLYPHYLY OF THE GENUS CYSTOSEIRA AND OTHER SARGASSACEAE GENERA (PHAEOPHYCEAE)1

Phylogenetic relationships in the Sargassaceae were explored using three DNA markers, and the monophyly of its genera was challenged. Nineteen out of 24 currently recognized genera were sampled, representing 63 species. The variable mt23S‐tRNA Val intergenic spacer could only be aligned within genera and could not be used to infer intergeneric relationships. The partial mt23S was also useful to delineate genera and was alignable at the family level but provided few informative characters. Analysis of mt23S DNA sequences together with chloroplast‐encoded psbA sequences resulted in a better resolved phylogeny. Hormophysa was the first genus to branch off within the Sargassaceae, followed by Myriodesma; then the three genera Caulocystis, Carpoglossum, and Scaberia in unresolved order; and then Acrocarpia. The other taxa studied here were divided over three major clades, but there was no branch support for the monophyly of two of these. The genera Bifurcaria, Cystoseira, Halidrys, and Sargassum appeared polyphyletic. The following taxonomic changes are proposed: a new genus Brassicophycus for Bifurcaria brassicaeformis (Kützing) E. S. Barton; reinstatement of the genus Sargassopsis for Sargassum decurrens (R. Brown ex Turner) C. Agardh; reinstatement of the genus Sirophysalis for Indo‐Pacific Cystoseira trinodis (Forsskål) C. Agardh; reinstatement of the genus Polycladia for the western Indian Ocean species Cystoseira indica (Thivy et Doshi) Mairh, Cystoseira myrica (S. G. Gmelin) C. Agardh, and Acystis heinii Schiffner; and reinstatement of the genus Stephanocystis for the North Pacific Cystoseira species and Halidrys dioica N. L. Gardner. The European Cystoseira species should be split into three genera, but no name changes are proposed yet, because diagnostic characters were found only for the clade including the type species. Some evolutionary trends could be discerned from the mt23S + psbA phylogeny.

Antibacterial Activity of Extracts from Selected Marine Algae in Bahrain

In this study, the bioactivity of some algal extracts were evaluated in vitro against different bacterial strains. Five commonly occurring benthic algae, namely Cystoseira myrica, Digenea simplex, Hormophysa triquetra, Sargassum cervicorne and Sarconema filiforme, were collected from Bahrain’s coastline in July 2007. A total of six chemical extracts were derived from those algal species, four of which were prepared by Soxhlet (petroleum ether, chloroform, ethyl acetate, methanol), aqueous and crude methanol. Their bioactivity was assessed against four testing bacterial strains using the agar well diffusion assay and expressed as the diameter of inhibition zone (mm). Results revealed that the petroleum ether extract of D. simplex exhibited the highest inhibition zone (24.3 mm) against Pseudomonas aeruginosa while the aqueous extract of C. myrica exhibited the lowest inhibition zone (13.3 mm) against Staphylococcus aureus. The Soxhlet extracts of all the algal species were biologically active only against P. aeruginosa. The aqueous extracts showed an inhibitory activity against S. aureus only. The crude methanolic extract was biologically broadly active on a wide range of tested bacteria, P. aeruginosa, Escherichia coli and Bacillus subtilis. The bacterium P. aeruginosa was the most susceptible microbe whereas S. aureus was the most resistant. On the average, The gram-negative bacteria tested were more sensitive than the gram-positive bacteria towards the extracts of the algal species used. The algal species that belong to the red algae class Rhodophyceae were more biologically active than algal species that belong to the brown algae class Phaeophyceae.

Cytotoxic activity of some marine brown algae against cancer cell lines.

The aim of this study was to investigate the in vitro cytotoxic activity of total extract of MeOH (70%) and partition fractions of hexan, chloroform (CHCL3), ethylacetate (EtOAc) and MeOH-H2O of brown algae species (Sargassum swartzii, Cystoseira myrica, Colpomenia sinuosa) found in the Persian Gulf against in different cell lines including HT-29, Caco-2, T47D, MDA-MB468 and NIH 3T3 cell lines by MTT and AnnexinV-PI assay. The hexan fraction of S. swartzii and C. myrica showed selective cytotoxicity against proliferation of Caco-2 cells (IC50 < 100 μg/ml) T47D cell line (IC50<100 μg/ml), respectively. S. swartzii and C. myrica were also observed for increasing apoptosis in Caco-2 and T47D cells. Total extract and fractions of C. sinuosa did not show any significant cytotoxicity against the studied cell lines. MDA-MB468 cells were more sensitive to C. myrica than was T47D (IC50 99.9 ± 8.11 vs. 56.50' ± 0.88). This reflects an estrogen receptor independent mechanism for cytotoxicity of the extract. The IC50 of the hexan fraction of C. myrica on T47D parent cells was lower than it was on T47D-TR cells (IC50 99.9 ± 8.11 vs. 143.15 ± 7.80). This finding suggests a role for the MDR-1 in the development of possible future tolerance to the extract.

Cytotoxic activity of some marine brown algae against cancer cell lines

The aim of this study was to investigate the in vitro cytotoxic activity of total extract of MeOH (70%) and partition fractions of hexan, chloroform (CHCL3), ethylacetate (EtOAc) and MeOH-H2O of brown algae species (Sargassum swartzii, Cystoseira myrica, Colpomenia sinuosa) found in the Persian Gulf against in different cell lines including HT-29, Caco-2, T47D, MDA-MB468 and NIH 3T3 cell lines by MTT and AnnexinV-PI assay. The hexan fraction of S. swartzii and C. myrica showed selective cytotoxicity against proliferation of Caco-2 cells (IC50 < 100 μg/ml) T47D cell line (IC50<100 μg/ml), respectively. S. swartzii and C. myrica were also observed for increasing apoptosis in Caco-2 and T47D cells. Total extract and fractions of C. sinuosa did not show any significant cytotoxicity against the studied cell lines. MDA-MB468 cells were more sensitive to C. myrica than was T47D (IC50 99.9 ± 8.11 vs. 56.50' ± 0.88). This reflects an estrogen receptor independent mechanism for cytotoxicity of the extract. The IC50 of the hexan fraction of C. myrica on T47D parent cells was lower than it was on T47D-TR cells (IC50 99.9 ± 8.11 vs. 143.15 ± 7.80). This finding suggests a role for the MDR-1 in the development of possible future tolerance to the extract.

3-Keto-22-epi-28-nor-cathasterone, a brassinosteroid-related metabolite from Cystoseira myrica

Bioassay-guided purification of an ethanolic extract of Cystoseira myrica against HEPG-2 (liver) and HCT116 (colon) human cancer cell lines led to the isolation of 3-keto-22-epi-28-nor-cathasterone, 1 and cholest-4-ene-3,6-dione, 2. This finding allowed us to report for the first time that a brassinosteroid-related metabolite occurs in seaweed. These compounds showed activity in the range of 12.38–1.16 μM with selective activity of compound 2 to liver cancer cell lines.

Biosorption of Copper(II) from Aqueous Solutions by Brown Macroalga Cystoseira myrica Biomass

Abstract Nowadays, heavy metals pollution of water resources represents an important environmental problem due to thier toxic and carcinogenic effects and accumulation throughout the food chain. In...

English

The hot water extract of a brown marine alga,&nbsp;Cystoseira myrica,&nbsp;from the Persian Gulf was evaluated as an antiviral compound against KOS strain of HSV-1 in cell culture.&nbsp;The extract exhibited antiviral activity against herpes simplex virus type 1 (HSV-1) not only during absorption of virus to the cells, but also on post attachment stages of virus replication.&nbsp;The water extract of&nbsp;C. myrica&nbsp;was sterilized by filtration and autoclaving, respectively. The IC50&nbsp;for filtered extract was 99 &micro;g/ml and the IC50&nbsp;for autoclaved extract was 125 &micro;g/ml.&nbsp;Based on resulted selectivity index (SI) values of the extracts, which were 33.4 and 28.2 for filtered and autoclaved extracts, respectively, we found that the antiviral compound(s) in the water extract&nbsp;of&nbsp;C. myrica&nbsp;to be heat stable.&nbsp;Also, the SI values for inhibition of the post attachment stages of HSV-1 replication were 23.1 and 21.7 for filtered and autoclaved extracts, respectively.&nbsp;The IC50&nbsp;in this phase of study were 143 and 162 &micro;g/ml for filtered and autoclaved extracts, respectively.&nbsp;Therefore,&nbsp;C. myrica&nbsp;could be a good candidate as a natural source for anti-HSV-1 compound(s) isolation. &nbsp; Key words:&nbsp;Cystoseira myrica, HSV-1, antiviral, Persian Gulf.

Distribution of Seagrasses and Common Seaweeds Around Nampula Province (Northern Mozambique) with Emphasis on Moçambique Island

The diversity and distribution of seagrasses and common seaweeds in Nampula province was studied. The field work took place between January and April 2002. 11 seagrasses and 53 common seaweed species were identified at Mocambique Island. From all studied sites, Fernao Veloso and Mocambique were the most diverse in seagrasses whereas Relanzapo and Ilha-dos-Sete-Paus in seaweeds. Seagrasses and seaweeds were mapped in Mocambique Island and grouped in nine community types namely: Thalassia hemprichii/ Halodule wrightii, Thalassia hemprichii/ macroalgae, Sargassum spp. / Cystoseira spp, Nanozostera capensis/Cymodocea rotundata/ Halodule wrightii, Cymodocea rotundata, Thalassodendron ciliatum/ Macroalgae, Thalassodendron ciliatum/Syringodium isoetifolium, Thalassodendron ciliatum , and Syringodium isoetifolium . All the above communities covered up to 70% of the total intertidal area, with Thalassia hemprichii /macroalgae being the largest community in Mocambique Island. Common species such as Thalassodendron ciliatum, Syringodium isoetifolium , and Sargassum spp. occur mainly in sublittoral fringe; while Thalassia hemprichii, Cystoseira myrica Laurencia papillosa at midlittoral and Enteromorpha and some Ulva sp. close to the shoreline. The present study contributes to fill up the lack of information regarding the community ecology of seagrass and seaweed in the Nampula province. Keywords : Seagrass, seaweed, diversity and distribution, Northern Mozambique, Western Indian West Indian Ocean Journal of Marine Science Vol. 4 (2) 2005: pp. 175-184

Heavy metal concentrations in marine green, brown, and red seaweeds from coastal waters of Yemen, the Gulf of Aden

The purpose of this study was to investigate the concentration levels of heavy metals in different species of the main three marine algal divisions from the Gulf of Aden coastal waters, Yemen. The divisions included Chlorophyta—green plants (Halimeda tuna, Rhizoclonium kochiamum, Caldophora koiei, Enteromorpha compressa, and Caulerpa racemosa species), Phaeophyta—brown seaweeds (Padina boryana, Turbinaria elatensis, Sargassum binderi, Cystoseira myrica, and Sargassum boveanum species), and Rhodophyta—red seaweeds (Hypnea cornuta, Champia parvula, Galaxaura marginate, Laurencia paniculata, Gracilaria foliifere, and species). The heavy metals, which included cadmium (Cd), cobalt (Co), copper (Cu), chromium (Cr), Iron (Fe), manganese (Mn), nickel (Ni), lead (Pb), zinc (Zn), and vanadium (V) were measured by Atomic Absorption Spectrophotometer (AAs). The concentrations of heavy metals in all algal species are in the order of Fe >> Cu > Mn > Cr > Zn > Ni > Pb > Cd > V > Co. The results also showed that the uptake of heavy metals by different marine algal divisions was in the order of Chlorophyta > Phaeophyta > Rhodophyta. These heavy metals were several order of magnitude higher than the concentrations of the same metals in seawater. This indicates that marine alga progressively uptake heavy metals from seawater.

INDUCTION AND REDUCTION OF ANTI‐HERBIVORE DEFENSES IN BROWN AND RED MACROALGAE OFF THE KENYAN COAST1

Herbivory is particularly intense in tropical benthic communities, suggesting preference of constitutive, rather than inducible, anti‐herbivory defense. The objective of the study was to examine whether anti‐herbivore defenses in the red alga Hypnea pannosa J. Agardh and the brown algae Sargassum asperifolium Hering and G. Martens ex J. Agardh and Cystoseira myrica (S.G. Gmelin) C. Agardh could be induced and subsequently reduced in response to grazing by the amphipod Cymadusa filosa Savigny. During a 14‐day treatment phase, algae were exposed to amphipod grazing or were left ungrazed (control). Subsequently, one subset of algae was used in feeding assays, whereas another was cultivated for additional 14 days without consumers (recovery phase). At the end of each phase, bioassays were conducted to detect defensive traits in terms of differences in consumption rates of grazed and control pieces of live algae and agar‐based food containing nonpolar algal extracts. Consumption of grazed live S. asperifolium and H. pannosa specimens was lower than of control algae. Furthermore, nonpolar extracts of grazed S. asperifolium and C. myrica were less preferred than those from control algae. Defensive responses were exclusively detected after the treatment phase, although strong preference of ungrazed H. pannosa and C. myrica over grazed conspecifics continued throughout the recovery phase. These findings suggest that phenotypic plasticity in anti‐herbivory defense of marine macroalgae 1) might be more common than previously shown, 2) could be switched on and off within 2 weeks, and 3) can be found in nonpolar algal extracts.