Spatial variation in early patterns of algal recruitment in a tropical intertidal community

Spatial variation in the patterns of early algal recruitment in a tropical intertidal shore was tested among different degrees of wave exposure and shore elevation levels. Algal recruitment showed a simple pattern. An ephemeral green alga, Ulva paradoxa was the early colonist that had high coverage and Padina in Vaughaniella stage and Polysiphonia sphaerocarpa were late successional algae that had very low coverage. This might be because Ulva is an opportunist pioneer species that reproduces all the year round with a large numbers of motile gametes and has a fast colonization, while those two species are slower colonizers. The degree of wave exposure and shore elevation level had no significant effect on the percentage covers of three dominant algae. However, the plots cleared at the exposed shore had the lowest percent cover of three algal species and algal species diversity, because the arrival and settlement of new recruits were influenced by wave action and absence of a stable and suitable substrate

ผลของการกินของสัตว์กินพืชและฤดูการของการเปิดพื้นที่ว่างต่อองค์ประกอบชนิดและการเปลี่ยนแปลงแทนที่ของสาหร่าย ณ อุทยานแห่งชาติสิรินาถ จังหวัดภูเก็ต

Thesis (M.Sc., Ecology)--Prince of Songkla University, 200

Growth rate and calcium carbonate accumulation of Halimeda macrolobaDecaisne (Chlorophyta: Halimedaceae) in Thai waters

Halimeda macroloba Decaisne can utilize the CO2 used for carbon fixation in photosynthesis and use bicarbonate as the main carbon source for calcification. Although Halimeda has been recognized as a carbon sink species, the calcium accumulation of Halimeda species in Thai waters remain poorly understood. In this study, the highest density of H. macroloba was 26 thalli/m2 and Halimeda quickly produced 1-2 new segments/thallus/day or 20.1 mg dry weight/thallus/day. Its calcium carbonate accumulation rate was 16.6 mg CaCO3 /thallus/day, or 82.46 % per thallus. In Thailand, however, only three scientific papers of growth rate and CaCO3 accumulation rate of H. macroloba have been found and collected. Of these records, the mean density was 26-104 thalli/m2 . The growth rate of H. macroloba was around 1-2 mg dry weight/day and the CaCO3 accumulation rate varied around 41-91%. Thus, Halimeda has a great potential to decrease the carbon dioxide concentration in the ocean

Water depth outweighs reef condition in shaping non-geniculate coralline algae-associated microbial communities in coral reefs: A case study from Thailand

Red calcified non-geniculate coralline algae (NGCA) provide habitat structures, stabilize reef structures, and foster coral larval settlement and metamorphosis. Moreover, the microbes associated with NGCA are dependent on the NGCA host species and are affected by environmental factors; however, little is known about the influence of reef conditions and depth gradients on the associated microbial communities and NGCA. In this study, we collected NGCA under different reef conditions and depth gradients and characterized the microbial communities using the V3–V4 hypervariable regions of the 16S rRNA gene. Metagenomic analysis revealed 2 domains, 51 phyla, 123 classes, and 210 genera. The NGCA-associated bacterial communities were dominated by Proteobacteria, Bacteroidetes, Chloroflexi, Actinobacteria, and Acidobacteriota. Gammaproteobacteria and Alphaproteobacteria were the most abundant bacterial classes. Differences in microbial diversity and richness were not apparent between reef conditions and depth gradients. However, there was a significant difference in bacterial evenness among the depth gradients. The bacterial abundance associated with NGCA was greater in deep zones than in shallow zones. The shallow zone exhibited a greater relative abundance of all gene functions than the deep zone, indicating differences in the distribution of gene functions. This study showed that the microbial communities associated with red calcified NGCA are diverse, and that the depth gradient affects their abundance and evenness, highlighting the need for further research to understand the functional roles of these microbial communities in coral reef conservation

The effects of herbivore exclusion and nutrient enrichment on growth and reproduction of Halimeda macroloba

ABSTRACT: The questions on how Halimeda macroloba allocates resources to growth and sexual reproduction when encountering herbivores and elevated nutrient concentrations were experimentally examined in the natural subtidal zone and in water tanks. The field experimental design comprised 96 plots (50 × 50 cm 2 ), with and without herbivores, and two nutrient levels. Cages were used to exclude fish herbivores: uncaged plots and fully caged plots; and 2 nutrient levels were manipulated: enriched and ambient levels in order to determine the effect of nutrients. Osmocote slow-release fertilizer was placed in each enriched plot. For the outdoor water tank experiments, mechanical clipping was used to simulate grazing on algae. Nutrient enrichment had a positive effect on the growth and reproduction of H. macroloba both in the field and water tank experiments, and herbivory or simulation of grazing did have a significant effect on the growth of algae in the water tank experiments. H. macroloba produced gametangia within 1-2 weeks after nutrient enrichment, to indicate that enrichment might be the trigger for reproduction of H. macroloba. From the tissue nutrient levels, the C:N, C:P, and N:P (18.9, 639, and 33.7) ratios indicated that the productivity of H. macroloba was phosphorus limited

The Proteome Profile of <i>Halimeda macroloba</i> under Elevated Temperature: A Case Study from Thailand

An elevated sea temperature is considered a key abiotic stressor causing thermal stress to intertidal macroalgae and influencing their populations. Halimeda macroloba is an important CaCO3 producer that contributes to the carbonate budget in marine ecosystems. The population decline of this intertidal algal species could lead to considerable declines in both regional and global carbonate production. However, the impact of increasing temperature on the molecular mechanisms and protein profile of calcified H. macroloba is unclear and remains to be explored. In this study, H. macroloba was exposed to 30 °C and 35 °C for 7 days. The whole protein was then extracted using 0.5% SDS and digested using trypsin before an analysis using LC-MS. The protein profile of H. macroloba was characterized using the MaxQuant program aligned with the UniProt database. A total of 407 proteins were identified, and 12 proteins were found to be significantly upregulated or downregulated in response to the elevated temperature. Cell division protein, protein kinase domain-containing protein, phospholipid transport protein, and small ribosomal subunit protein were the significant proteins identified in our dataset. The proteins associated with cell division, cellular metabolic processes, localization, oxidoreductase activity, and biosynthetic process pathways were overexpressed with a more than 2-fold change at a high temperature. An interaction map generated using STITCH revealed that the significant protein change altered the other proteins related to abiotic stress, producing energy and inducing calcification. This information could be useful in understanding how H. macroloba responds to an elevated sea temperature

DIVERSITY AND COMMUNITY STRUCTURE OF MACROALGAE AT KOH TAEN, HAAD KHANOM-MU KOH TALE TAI, MARINE NATIONAL PARK, NAKHON SI THAMMARAT PROVINCE, THAILAND

The diversity and community structure of macroalgae at Koh Taen, Haad Khanom-Mu Koh Tale Tai, marine National Park, Nakhon Si Thammarat Province, Thailand were investigated from 1st- 5th October 2005 (preliminary survey). Out of a total of 41 species: 15 species each of green and red algae, 9 species of brown algae and 2 species of blue green algae were found. In the area, subsequently four sites were established for monitoring. Quadrat sampling was employed to assess the abundance of macroalgae. In total sixty quadrats were monitored each month from October 2005 to April 2007. We report the variations of diversity and abundance of macroalgae among sites and seasons and speculate about what might cause such variations

Carbon dioxide mitigation potential of seaweed aquaculture beds (SABs)

Seaweed aquaculture beds (SABs) that support the production of seaweed and their diverse products, cover extensive coastal areas, especially in the Asian-Pacific region, and provide many ecosystem services such as nutrient removal and CO2 assimilation. The use of SABs in potential carbon dioxide (CO2) mitigation efforts has been proposed with commercial seaweed production in China, India, Indonesia, Japan, Malaysia, Philippines, Republic of Korea, Thailand, and Vietnam, and is at a nascent stage in Australia and New Zealand. We attempted to consider the total annual potential of SABs to drawdown and fix anthropogenic CO2. In the last decade, seaweed production has increased tremendously in the Asian-Pacific region. In 2014, the total annual production of Asian-Pacific SABs surpassed 2.61 x 10(6) t dw. Total carbon accumulated annually was more than 0.78 x 10(6) t y(-1), equivalent to over 2.87 x 10(6) t CO2 y(-1). By increasing the area available for SABs, biomass production, carbon accumulation, and CO2 drawdown can be enhanced. The conversion of biomass to biofuel can reduce the use of fossil fuels and provide additional mitigation of CO2 emissions. Contributions of seaweeds as carbon donors to other ecosystems could be significant in global carbon sequestration. The ongoing development of SABs would not only ensure that Asian-Pacific countries will remain leaders in the global seaweed industry but may also provide an added dimension of helping to mitigate the problem of excessive CO2 emissions