BackgroundThe Indo-Pacific region has the largest number of seagrass species worldwide and this region is considered as the origin of the Hydrocharitaceae. Halophila ovalis and its closely-related species belonging to the Hydrocharitaceae are well-known as a complex taxonomic challenge mainly due to their high morphological plasticity. The relationship of genetic differentiation and geographic barriers of H. ovalis radiation was not much studied in this region. Are there misidentifications between H. ovalis and its closely related species? Does any taxonomic uncertainty among different populations of H. ovalis persist? Is there any genetic differentiation among populations in the Western Pacific and the Eastern Indian Ocean, which are separated by the Thai-Malay peninsula? Genetic markers can be used to characterize and identify individuals or species and will be used to answer these questions.ResultsPhylogenetic analyses of the nuclear ribosomal internal transcribed spacer region based on materials collected from 17 populations in the Western Pacific and the Eastern Indian Ocean showed that some specimens identified as H. ovalis belonged to the H. major clade, also supported by morphological data. Evolutionary divergence between the two clades is between 0.033 and 0.038, much higher than the evolutionary divergence among H. ovalis populations. Eight haplotypes were found; none of the haplotypes from the Western Pacific is found in India and vice versa. Analysis of genetic diversity based on microsatellite analysis revealed that the genetic diversity in the Western Pacific is higher than in the Eastern Indian Ocean. The unrooted neighbor-joining tree among 14 populations from the Western Pacific and the Eastern Indian Ocean showed six groups. The Mantel test results revealed a significant correlation between genetic and geographic distances among populations. Results from band-based and allele frequency-based approaches from Amplified Fragment Length Polymorphism showed that all samples collected from both sides of the Thai-Malay peninsula were clustered into two clades: Gulf of Thailand and Andaman Sea.ConclusionsOur study documented the new records of H. major for Malaysia and Myanmar. The study also revealed that the Thai-Malay peninsula is a geographic barrier between H. ovalis populations in the Western Pacific and the Eastern Indian Ocean.

Eucheuma striatum Schmilz was transplanted from the Philippines into the subtropical waters of Tosa Bay, Shikoku Island, Japan. The yearly Variation in temperature of the seawater at the culture site was 10.2 to 31.2 °C, turbidity was 0.1 to 3.7 ppm, and salinity was 31.17%o to 33.86%o. Plants were grown using a monoline method at a depth of ca l .0 m below the water surface. Plants could be grown from May to October, when the seawater temperature ranged from 20.9 to 31.2°C, with a growth rate of 1.4 to 5.9% day" 1 . The most favourable growth period was from August to October. Maximum biomass production, ca 9100% over the initial weight, was obtained after 5.5 months in October. Plants grown at a depth of 2.25 to 3.5 m did not have a significantly different growth rate from the plants grown nearer the surface (0.25 to 2.0 m). Plants produced cystocarps releasing many carpospores in October at temperatures of 21.1 to 24.8 °C.In the laboratory, plants were grown in artificial seawater made from synthetic sea salt 'Jamarin' U and enriched with a fertilizer (Norimax) under ranges of salinity, temperature, Illumination and photoperiod. Maximum growth, äs well äs fruiting, occurred in culture at 24 °C, 6 k lux Illumination, 12: 12h L/D cycle and culture media of 35.11%o salinity.

Polysiphonia subtilissima Montagne collected from Setse and Kyaikkhami coastal areas was carried out. The carpospores of P. subtilissima germinated at 25˚C under the photoperiod of 8L:16D and 30˚C under the photoperiod of 16L:8D, showing the early stages of cell divisions and development of thalli in culture. In the carpospores germination of P. subtilissima, primary rhizoid developed from lower cell after second cell division during 2days in culture. After 15days, the pericentral cells cut off and formed as polysiphonous structure in the young filamentous sprout with a total length of up to 1200µm. The carpospore germination pattern of P. subtilissima Montage of laboratory experiment was briefly discussed. Citation: San J, Soe-Htun U. Spore germination on Polysiphonia subtilissima Montagne from Setse and Kyaikkhami coastal areas, Thanlwin river mouth, Myanmar. Citation: San J, Soe-Htun U. Spore germination on Polysiphonia subtilissima Montagne from Setse and Kyaikkhami coastal areas, Thanlwin river mouth, Myanmar.

Seagrass surveys were conducted at 9 study sites, in the southern Rakhine Coastal Region, to assess the species diversity, percent cover and extent of seagrasses for the better understanding of the current status and suitability of seagrass meadows for MPA designation. Among 9 study sites, except for Ma Gyi and Pho Htaung, the remaining 7 sites such as Tharthanar Dauk, Ngwe Saung, Wet Thay, Baw Di, Chan Pyin, Yay Myet Taung and Gyaing Kauk were newly recorded sites in the present surveys. There are two types of seagrass habitats: 1) intertidal habitats, mainly in shallow rock-pools at Baw Di and Yay Myet Taung; and 2) predominantly subtidal habitats at the remaining study sites. In the present surveys, a total of 10 species of seagrasses, namely Syringodiumisoetifolium, Cymodoceaserrulata, C. rotundata, Haloduleuninervis, H. pinifolia, Enhalusacoroides, Thalassiahemprichii, Halophilabeccarii, H. decipiensand H. major had been recorded. Among these, only one, Halophilabeccarii is was listed as Vulnerable on the IUCN RedList, while all other species were listed as Least Concern. Halophilabeccarii was only recorded at Pho Htaung. Halodulepinifolia was the most commonly observed species which was found in the remaining eight study sites. Pho Htaung, with the highest number of species (10 species) and coverage (66.9%), and as the only site to contain the Vulnerable Halophilabeccarii, should be assigned to a Marine Protected Area (MPA), as well as along with Ma Gyi and Chan Pyin given their high species diversity and coverage.

A total of 261species of marine benthic algae under 121genera,comprising 72 taxa belonging to 26 genera of Chlorophyta, 45 taxa belonging to 18 genera of Phaeophyta and 144 taxa belonging to 77 genera of Rhodophyta growing along the Tanintharyi Coastal Zone, Deltaic Coastal Zone and Rakhine Coastal Zone, were recorded. In general, diversity ratios of seaweeds occur in 3 Coastal Zones is 3:1:4 between the Tanintharyi Coastal Zone (146 taxa), Deltaic Coastal Zone (53 taxa) and Rakhine Coastal Zone (224 taxa).Among these, 89 species of marine benthic algae, including 25 taxa of green, 9 taxa of brown and 55 taxa of red algae, were newly recorded from Myanmar waters. The latitudinal distribution of marine benthic algae along the Myanmar Coastal Zones reveals 25 species of marine benthic algae which uniquely occur in low lattitute in the Tanintharyi Coastal Zone and 111 species which exclusively predominate in high lattitutein the Rakhine Coastal Zone. Monostroma, Ulva, Caulerpa and Codium of Chlorophyta, Dictyota, Spatoglossum, Hormophysa, Turbinaria and Sargassum of Phaeophyta and Phycocalidia, Dermonema, Gelidiella, Halymenia, Solieria, Hypnea, Gracilaria,Gracilariopsis, Hydopuntia, Catenella and Acanthophora of Rhodophyta could be considered as of dependable natural resources of Myanmar to produce the sea-vegetables and phycocolloids. Mariculture of some economically important marine red algae such as Gracilaria spp., Hydopuntia spp., Catenella spp. And Kappaphycus alvarezii was described. Current status and prospects of phycocolloid industries producing alginate, agar-agar and carrageenansfrom raw materials of seaweeds of Myanmar were discussed. Checklist, distribution and conservation of marine benthic algae were briefly presented.