Seagrass Enhalus Acoroides Research Articles

Different organs of Enhalus acoroides (Hydrocharitaceae) can serve as specific bioindicators for sediment contaminated with different heavy metals

The tropical seagrass Enhalus acoroides is considered as a potential bioindicator for heavy metals. To date, studies on the accumulation of heavy metals in each specific seagrass organ have been limited. In this study, surface sediment and E. acoroides samples collected at six distinct beds from the coast of Khanh Hoa province, Vietnam, were evaluated for their heavy metal concentrations (Cd, Cu, Pb and Zn) to determine which organs of E. acoroides could be used as bioindicators for heavy metals. The metal concentrations in both the sediment and the seagrass organs were measured using inductively coupled plasma mass spectrometry (ICP-MS). Bio-concentration factor (BCF) and Metal pollution index (MPI) were determined on the seagrass organs, and Pearson's correlation and ANOVA were used for statistical analysis. The results showed that the highest BCF values of Cd and Zn were found in leaves, the highest BCF value of Cu was found in the rhizomes and the highest BCF value of Pb was found in the roots. Generally, MPI was lower in the sediment than in seagrass organs at the same locations. For Cd, Pearson's correlation showed that a significant positive correlation was only observed between sediment and leaves with respect to BCF. A significant positive correlation of BCF for Cu was observed between sediment and rhizome while significant positive correlations of BCF for Cu, Pb and Zn were observed between sediment and roots. Based on the results, it can be concluded that E. acoroides leaves should be used as a bioindicator for Cd and Zn, rhizomes for Cu, and roots for the three metals Cu, Pb and Zn.

Phytochelatin 2 accumulates in roots of the seagrass Enhalus acoroides collected from sediment highly contaminated with lead.

Phytochelatins (PCs), the heavy metal-binding peptides of plants, play a main function in heavy metal detoxification. In this study, Enhalus acoroides samples collected at six distinct seagrass beds from the coast of Khanh Hoa province, Viet Nam, were evaluated for their PCs. The contents of different PCs in each organ including leaf, rhizome, and root were determined by using HPLC analysis. Significant differences of PC2 contents among specific organs and their relation were tested by ANOVA, Tukey test, and Pearson's correlation. The results showed that higher PC2, appearance of PC3 and a strong correlation between PC2 and Pb concentration were found in the root organ collected from a Pb contaminated area. We conclude that high Pb in the sediment induce high PC2 and PC3 production in the root. This first report on in situ detection of PCs of seagrass encourages future investigation on the ability to use seagrass for phytoremediation and as a bioindicator of heavy metals based on PC contents.

Typification of the Indo‐Pacific seagrass Enhalus acoroides (Hydrocharitaceae)

AbstractThe typification of the ecologically important and widely distributed Indo‐Pacific seagrass Enhalus acoroides (≡ Stratiotes acoroides, Hydrocharitaceae) is discussed. An illustration from Rumphius's Herbarium Amboinense is designated as the lectotype.

PCR-RFLP and Sequencing of trnS/trnfM Fragment of Enhalus acoriodes from Sanur Coastal Waters, Bali, Indonesia: A Preliminary Study

This study aimed to evaluate the resolution of PCR-RFLP and sequencing of trnS/trnfM in detecting genetic diversity of seagrass Enhalus acoroides at Sanur Beach, Sindhu Beach and Semawang Beach. This research used six samples E. acoroides from each location. DNA extraction method followed Doyle and Doyle. PCR amplifications were done using primers P672/P673, P674/P675 and ITS4/ITS5 followed by digestion using restriction enzymes EcoRI, PstI, HindIII, BamHI, Rsa, Mva and HinfI. Sequencing analysis used PCR products of primers trnS/trnfM. Testing of DNA sequences of E. acoroides were conducted using BLAST (Basic Local Alignment Search Tool). DNA sequences were further analyzed using MEGA 5.2 software (Molecular Evolutionary Genetic Analysis) to evaluate variations of DNA. The sequence alignments were done using ClustalW software to determine the homology between the DNA sequences. The results showed that 18 samples of E. acoroides from Sanur, Sindhu and Semawang Beach have no polymorphism based on restriction enzyme analyses. Furthermore, sequencing of trnS/trnfM region of 18 samples E. acoroides showed that the sequences were identical.

Cover and Issue Information

New PhytologistVolume 210, Issue 4 p. 1145-1148 Cover and Issue InformationFree Access Cover and Issue Information First published: 09 May 2016 https://doi.org/10.1111/nph.13667AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat Graphical Abstract Cover Legend Air-exposed, desiccating leaf tips of the seagrass Enhalus acoroides in a shallow tropical pool in the Kimberley region of Australia. Courtesy of Ole Pedersen. (Pedersen et al. pp. 1207–1218) Volume210, Issue4June 2016Pages 1145-1148 RelatedInformation

Enhalus acoroides responses to experimental shoot density reductions in Haad Chao Mai National Park, Trang Province, Thailand

AbstractThe effect of self‐shading and competition for light in the seagrass Enhalus acoroides were investigated with a density reduction experiment in Haad Chao Mai National Park, Trang Province, Thailand. The study was carried out in a monospecific meadow with a natural density of 141.0 ± 8.7 shoots·m−2. The intent was to determine the response of E. acoroides beds to loss of shoots and thinning, which often occur during typhoons and severe storm activity. Permanent quadrats were manipulated by clipping the seagrass shoots to 140, 72, 36 and 16 shoots·m−2, to yield natural, 50%, 25% and 10% densities, respectively. Reducing shoot density in E. acoroides increased underwater light intensity below the canopy, generating increased leaf surface area and shoot weight. Seagrass leaf width, growth rate, and number of leaves per shoot also increased with greater light. The extent of flowering varied among treatments with no consistent trend. Our results demonstrate that increasing the available light to E. acoroides produces an increasing leaf size response as self‐shading in the bed is reduced.

Responses of bacterial communities in seagrass sediments to polycyclic aromatic hydrocarbon-induced stress.

The seagrass meadows represent one of the highest productive marine ecosystems, and have the great ecological and economic values. Bacteria play important roles in energy flow, nutrient biogeochemical cycle and organic matter turnover in marine ecosystems. The seagrass meadows are experiencing a world-wide decline, and the pollution is one of the main reasons. Polycyclic aromatic hydrocarbons (PAHs) are thought be the most common. Bacterial communities in the seagrass Enhalus acoroides sediments were analyzed for their responses to PAHs induced stress. Dynamics of the composition and abundance of bacterial communities during the incubation period were explored by polymerase chain reaction denaturing gradient gel electrophoresis (PCR-DGGE) and quantitative PCR assay, respectively. Both the incubation time and the PAHs concentration played significant roles in determining the microbial diversity, as reflected by the detected DGGE bands. Analysis of sequencing results showed that the Gammaproteobacteria were dominant in the seagrass sediments, accounting for 61.29 % of all sequenced bands. As PAHs could be used as carbon source for microbes, the species and diversity of the PAH-added groups (group 1 and 2) presented higher Shannon Wiener index than the group CK, with the group 1 showing the highest values almost through the same incubation stage. Patterns of changes in abundance of the three groups over the experiment time were quite different. The bacterial abundance of the group CK and group 2 decreased sharply from 4.15 × 10(11) and 6.37 × 10(11) to 1.17 × 10(10) and 1.07 × 10(10) copies/g from day 2 to 35, respectively while bacterial abundance of group 1 increased significantly from 1.59 × 10(11) copies/g at day 2 to 8.80 × 10(11) copies/g at day 7, and then dropped from day 14 till the end of the incubation. Statistical analysis (UMPGA and PCA) results suggested that the bacterial community were more likely to be affected by the incubation time than the concentration of the PAHs. This study provided the important information about dynamics of bacterial community under the PAHs stress and revealed the high bacterial diversity in sediments of E. acoroides. Investigation results also indicated that microbial community structure in the seagrass sediment were sensible to the PAHs induced stress, and may be used as potential indicators for the PAHs contamination.

Nitrogen dynamics on Guam as revealed by the seagrass Enhalus acoroides

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 528:117-126 (2015) - DOI: https://doi.org/10.3354/meps11270 Nitrogen dynamics on Guam as revealed by the seagrass Enhalus acoroides K. Pinkerton1, D. M. Baker2, M. R. Cuddy1, L. J. Raymundo3, K. A. Meyer1, K. Kim1,* 1Department of Environmental Science, American University, 4400 Massachusetts Ave NW, Washington, DC 20016, USA 2School of Biological Sciences & Department of Earth Science, University of Hong Kong, Kadoorie Biological Sciences Building, Pokfulam Road, Hong Kong SAR 3University of Guam Marine Laboratory, UOG Station, Mangilao, GU 96923, USA *Corresponding author: kiho@american.edu ABSTRACT: Seagrasses are critical to productive coastal ecosystems but are endangered and poorly studied, especially in the tropical Indo-Pacific. A key local threat is the increasing anthropogenic input of nitrogen (N). We hypothesized that such N eutrophication is occurring on Guam, the largest and most populated of the Northern Mariana Islands. We examined the seagrass Enhalus acoroides over 5 years and applied stable isotope analysis to document N dynamics and impacts. Although δ15N values indicated that sewage-derived N was the dominant source, the δ15N values were unrelated to either seagrass cover or growth rate. Strong relationships between seagrass δ15N values and both distance to the nearest source of N inputs and population density of adjacent municipalities suggest that N inputs are highly localized. Although there was no evidence of a negative impact of sewage-derived N inputs on seagrasses, this study provides a useful reference for evaluating mitigation efforts and for tracking the effect of increasing anthropogenic eutrophication on Guam. KEY WORDS: Seagrasses · Tropical Indo-Pacific · Stable isotope analysis · Eutrophication Full text in pdf format PreviousNextCite this article as: Pinkerton K, Baker DM, Cuddy MR, Raymundo LJ, Meyer KA, Kim K (2015) Nitrogen dynamics on Guam as revealed by the seagrass Enhalus acoroides. Mar Ecol Prog Ser 528:117-126. https://doi.org/10.3354/meps11270 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 528. Online publication date: May 28, 2015 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2015 Inter-Research.

Hyperspectral Reflectance Response of Seagrass (Enhalus acoroides) and Brown Algae (Sargassum sp.) to Nutrient Enrichment at Laboratory Scale

Abstract Suwandana, E.; Kawamura, K.; Sakuno, Y.; Evri, M., and Lesmana, A.H., 2012. Hyperspectral reflectance response of seagrass (Enhalus acoroides) and brown algae (Sargassum sp.) to nutrient enrichment at laboratory scale. Coastal environments are prone to nutrient contamination as a result of excessive use of fertilizers in paddy agriculture on the land. To detect nutrient increases in coastal areas, researchers have used hyperspectral reflectance response to examine some coastal plants, which have proved to be effective as bioindicators. In this study, field hyperspectral technique was evaluated as a tool to detect nutrient concentrations in two coastal plants, i.e., seagrass (Enhalus acoroides) and brown algae (Sargassum sp.), taken from Banten Bay Indonesia, at laboratory scale. Although our initial experiments are still too few in elucidating an accurate relationship of nutrients and spectral signature, we are pleased to communicate that there is scientific evidence that hyperspectral measuremen...

Development of novel microsatellite markers in a tropical seagrass, Enhalus acoroides

Using the dual-suppression polymerase chain reaction technique, 12 novel polymorphic nuclear microsatellite DNA markers were isolated from the tropical seagrass Enhalus acoroides. The isolated markers provided the polymorphisms of 2–13 alleles per locus in 3 populations located in Japan, China, and the Philippines. The values of the expected heterozygosity fell in the following ranges: 0.000–0.693 (Japan), 0.000–0.623 (China), and 0.000–0.765 (Philippines). Compared to the Philippines population (1 monomorphic locus), a relatively higher proportion of the SSR loci did not show polymorphism in the marginal habitats of E. acoroides (5 loci in Japan; 5 loci in China). These markers may be useful for population and conservation genetics of E. acoroides.

Development of microsatellite primers of the largest seagrass, Enhalus acoroides (Hydrocharitaceae)

Microsatellite primers were developed for the seagrass Enhalus acoroides to investigate genetic variation and identify clonal structure. Four polymorphic loci and 32 monomorphic loci were developed in E. acoroides. Two to four alleles per locus were observed at the polymorphic loci across 60 individuals of two E. acoroides populations. The observed and expected heterozygosities within populations ranged from 0.100 to 0.5667 and from 0.0977 to 0.5079, respectively. Our study revealed very low polymorphism in E. acoroides, even at the polymorphic loci. Nevertheless, these primers are a useful tool to study genetic variation, clonal structure, and mating system.

Seed Germination and Seedling Development of the Seagrass Enhalus acoroides (L.f.) Royle in vitro: Effects of Burial Depths and Desiccation Periods

This study provides information on the feasibility of using Enhalus acoroides seeds as source of seedling materials for seagrass restoration effort and to support wider conservation initiatives. Mature seeds of E. acoroides were collected from Tubajon, Laguindingan, Misamis Oriental and were subjected to different laboratory conditions, namely burial depths and desiccation periods, to determine germination rate, seedling growth, and development. Seeds placed just above (control) and half-buried in the sediment fully germinated on the first day, while germination of fully buried seeds was delayed, attaining 93.3% germination on the fourth day. Seeds planted at 5 mm burial depth started germinating on the fifth day with only 56.7% germination success, while seeds buried deeply (15mm) did not germinate. All seeds subjected to desiccation germinated, but higher seedling survival (93.3 - 100%) was observed when seeds were desiccated at shorter periods of up to two hours while the lowest seedling survival (64.8%) was observed after a 12h desiccation period. One-way ANOVA showed significant differences in seedling survival and shoot length (p 0.05). Results have demonstrated that seed germination and the subsequent seedling development were adversely affected by burial depths and desiccation periods. Seedlings at 5mm burial depth and 12h desiccation period exhibited black and white spots, curled and yellowish leaves, stunted growth, and high mortality rates.

Phylogenetic diversity of endophyte assemblages associated with the tropical seagrass Enhalus acoroides in Thailand

Seagrasses are flowering plants inhabiting coastal and marine environments, with a worldwide distribution. They serve as feeding, breeding and nursery grounds for economically important marine organisms including endangered species. The tropical seagrass Enhalus acoroides was collected from Had Khanom-Mu Ko Thale Tai National Park, southern Thailand. The objectives of this study were to investigate for the presence of endophyte assemblages in E. acoroides, as well as to describe the diversity of endophytes based on LSU, ITS1, 2, 5.8S rDNA sequence analyses. Forty-two fungal assemblages were isolated and identified through molecular data. This resulted in a diversity of fungal groups of Ascomycota (98%) and Basidiomycota (2%). Three major Ascomycota classes including the Sordariomycetes (36%), Eurotiomycetes (33%) and Dothideomycetes (24%) were determined. The predominant ascomycete orders were the Hypocreales, followed by the Eurotiales and the Capnodiales, respectively. Additionally one taxon belonged to the Russulales, Basidiomycota and was possibly mycorrhiza. This study confirms that E. acoroides harbors a wide diversity of fungal endophytes, and provides a baseline for further studies on fungal-host plant interactions.

Antifeedant, antibacterial, and antilarval compounds from the South China Sea seagrass Enhalus acoroides

Abstract We investigated chemical constituents and the antifeedant, antibacterial, and antilarval activities of EtOH (ethanol) extracts of the South China Sea seagrass Enhalus acoroides. Eleven pure compounds including four flavonoids and five steroids were obtained. Among these compounds, three flavonoids were antifeedant against second-instar larvae of Spodoptera litura, two flavonoids had antibacterial activity towards several marine bacteria, and one flavonoid showed strong antilarval activity against Bugula neritina larvae. This is the first description of isolation and bioactivity of secondary metabolites from E. acoroides.

Beberapa Aspek Pertumbuhan Lamun Enhalus acoroides (Linn. F) Royle di Pulau Barrang Lompo Makassar

A study has been conducted to investigate some aspects related to seagrass Enhalus acoroides growth in Barrang Lompo Island Makassar by using a modified tagging method. Tagging was applied monthly to 20 seagrass stands for seven months with weekly observations. The results showed that Enhalus acoroides growth had a quadratic pattern and was strongly affected by exposed environmental condition, turbidity, nutrient, and temperature .

Internal variations in nutrient concentrations and the C and N stable isotope ratios in leaves of the seagrass Enhalus acoroides

We analyzed the content of tissue nutrients (carbon, nitrogen, and phosphorus), the C:N:P ratio, the carbon stable isotope ratio ( δ 13 C ) and the nitrogen stable isotope ratio ( δ 15 N ) of leaves of Enhalus acoroides (L. f.) Royle growing in two submerged beds in southwest Thailand. The N and P concentrations and δ 15 N decreased with increasing distance along the leaf. The maximum ranges in one leaf were 1.80–4.05% for N, 2.85–6.64 mg g −1 for P, and 1.28–2.93‰ for δ 15 N . The C:N, C:P, and N:P ratios increased as the distance along the leaf increased. The maximum ranges in one leaf were 12.5–24.3 for C:N, 162–622 for C:P, and 14.0–28.9 for N:P. In contrast, C concentration and δ 13 C fluctuated with distance along the leaf, and the longest leaves from each beds showed similar patterns of fluctuation. The variation of the chemical signature within leaves suggests that special attention is needed to apply these data to the evaluation of nutrient conditions during growth in food-web analyses involving seagrass beds.

Spatio-temporal variation in sexual reproduction of the tropical seagrass Enhalus acoroides (L.f.) Royle in Cape Bolinao, NW Philippines

The Indo-Pacific seagrass Enhalus acoroides (L.f.) Royle can reproduce by vegetative growth as well as sexually, by the production of seeds. To assess the role of environmental conditions in the occurrence of sexual reproduction in this dioecious species, spatio-temporal variation in flowering was investigated in the reef flats off Cape Bolinao, north-western Philippines. Flowering occurred year-round, but the intensity varied temporally and correlated with mean water temperature. Spatially, differences in flowering intensity correlated with available light as affected by turbidity and water depth. Exposure duration of female flowers to air seems to be crucial for pollination and subsequent seed setting, resulting in higher numbers of fruits in shallower sites. Contrary to previous hypotheses, no effect of tidal levels on the release of male flowers was observed. It is suggested that production of gas bubbles in photosynthesis plays a key role. The great discrepancy between observed flowering and the presence of peduncle scars on the rhizomes at the deeper sites suggests that early abortion is common here. The use of these scars to quantify flowering will lead to an overestimation of reproductive effort in deep sites. The rare occurrence of flowering in deep sites supports the contention that light availability is a key factor in successful flowering in E. acoroides. Allocation of biomass and nutrients (N, P) over various plant components suggests that sexual reproduction involves high cost in E. acoroides.

Proximate analysis of the flour and starch from Enhalus acoroides (L.f.) Royle seeds

The seeds of the tropical seagrass Enhalus acoroides were analyzed for their nutritive components to assess their dietary value for humans. Proximate analysis of flour prepared by grinding the dried seeds gave the following results: 9.8% moisture; 8.8% protein; 0.2% fat; 72.4% carbohydrates; 2.4% crude fiber; 6.4% ash; 933 mg/kg calcium; 2392 mg/kg phosphorous; and 2813 mg/kg iron. Correspondingly, proximate analysis of the starch prepared from the flour with a 50% yield, resulted in the following: 11% moisture; 0.8% protein; 0.1% fat; 87.6% carbohydrates; 0.4% crude fiber; 0.5% ash; 320 mg/kg calcium; 210 mg/kg phosphorous and; 220 mg/kg iron. Comparison of the proximate analysis results and the calculated caloric values of the seagrass seed flour and starch showed similarity with those of terrestrial origin.

The influence of seagrass type on the distribution and abundance of postlarval and juvenile tiger prawns ( Penaeus esculentus and P. semisulcatus) in the western Gulf of Carpentaria, Australia

Postlarval and juvenile tiger prawns ( Penaeus esculentus and P. semisulcatus) were sampled by beam trawls in different seagrass communities of the western Gulf of Carpentaria to test the influence of seagrass characteristics on their distribution and abundance. Two sampling regimes were carried out: fortnightly sampling over a 3 month period during the time of peak recruitment to investigate the importance of different seagrass types to tiger prawns; and at one time to investigate the wider geographic patterns of distribution and abundance of tiger prawns. The results from both studies showed that the pattern of distribution and abundance of 1–1.9 mm carapace length (CL) postlarvae differed from those for the 2–2.9 mm CL postlarvae and juvenile tiger prawns (≥3 mm CL). The 1–1.9 mm CL size class consists of individuals that are about to settle and those that have recently settled: this size class was more widely distributed than the larger postlarvae and juveniles and was sometimes found on substrates where no seagrass was present. Larger tiger prawns were found in higher numbers on seagrass beds where the tall, broad-leaved seagrass Enhalus acoroides was the dominant species. Although seagrass biomass was not a consistent linear predictor of juvenile tiger prawn numbers, mean catches of both the 2–2.9 mm CL postlarvae and juvenile P. esculentus were highest when the biomass of seagrass exceeded 100 g m −2. However, these high biomass seagrass beds contribute only 6% to the total extent of seagrasses in the shallow waters (<2.5 m deep) of the Gulf of Carpentaria. Although the numbers of juvenile tiger prawns were lower in the low-biomass seagrass beds, because of their extent, these seagrass beds are the main nurseries for sustaining the production of the valuable Northern Prawn Fishery in Australia.

Production and biomass of the seagrass Enhalus acoroides (L.f.) Royle and its epiphytes

Annual production and biomass of seagrasses and attached epiphytes was determined for Enhalus acoroides (L.f.) Royle from Papua New Guinea. The leaf growth rate, assessed with the marking technique, resulted in a constant rate during the first two months and was subsequently followed by a decrease in leaf growth of 0.37 mm day −1. The leaf growth increased with 1.8 mm day −1 for an increase of 1°C in water temperature. Production of the leaf blades and basal plant parts, was 17.5 and 5.2 mg ADW shoot −1 day −1, respectively. Total annual mean plant biomass (above- and below-ground), amounted to 600 g ADW m −2, of which the largest part (73%) was contributed by the rhizomes. Flowering occurred all year round. The maximum number of inflorescences (male and female) was observed in June. Successful fruit formation occurred predominantly between April and August. A total of 66 algal epiphytic species was identified on leaves of Enhalus acoroides of which the majority (in number and in abundance) was found in the shallower stations. Annual mean biomass of epiphytes varied from 22 to 78 mg ADW shoot −1. The epiphytes contributed 3–17% to the total annual mean above-ground plant biomass. Annual mean production of epiphytes ranged from 38.5–65 mg ADW m −2 day −1. An estimated 2–9% of the total annual mean above-ground plant production was produced by the epiphytic community.