Conversion of Calcified Algae (Halimeda sp) and Hard Coral (Porites sp) to Hydroxyapatite

Calcium phosphate materials can be produced using a number of wet methods that are based on hydrothermal or co-precipitation methods that might use acidic or basic chemical environments. In our previously published works, we have investigated calcium phosphates such as monetite, hydroxyapatite, and whitlockite which were successfully produced by mechano-chemical methods and/or hydrothermal treatments from a range of marine shells and corals which were obtained from the Great Barrier Reef. The aim of the current work was to analyze and compare the mechanisms of conversion of one hard coral species and one calcified algae species from the Great Barrier Reef

ความแปรผันตามฤดูกาลของการกระจายตัว ความหนาแน่น และช่วงชีวิตของสาหร่าย Halimeda macroloba Decaisne บริเวณอ่าวตังเข็น จังหวัดภูเก็ต

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

Calcification in Three Common Calcified Algae from Phuket, Thailand: Potential Relevance on Seawater Carbonate Chemistry and Link to Photosynthetic Process

Calcifying macroalgae contribute significantly to the structure and function of tropical marine ecosystems. Their calcification and photosynthetic processes are not well understood despite their critical role in marine carbon cycles and high vulnerability to environmental changes. This study aims to provide a better understanding of the macroalgal calcification process, focusing on its relevance concerning seawater carbonate chemistry and its relationship to photosynthesis in three dominant calcified macroalgae in Thailand, Padina boryana, Halimeda macroloba and Halimeda opuntia. Morphological and microstructural attributes of the three macroalgae were analyzed and subsequently linked to their calcification rates and responses to inhibition of photosynthesis. In the first experiment, seawater pH, total alkalinity and total dissolved inorganic carbon were measured after incubation of the macroalgae in the light and after equilibration of the seawater with air. Estimations of carbon uptake into photosynthesis and calcification and carbon release into air were obtained thereafter. Our results provide evidence that calcification of the three calcified macroalgae is a potential source of CO2, where calcification by H. opuntia and H. macroloba leads to a greater release of CO2 per biomass weight than P. boryana. Nevertheless, this capacity is expected to vary on a diurnal basis, as the second experiment indicates that calcification is highly coupled to photosynthetic activity. Lower pH as a result of inhibited photosynthesis under darkness imposes more negative effects on H. opuntia and H. macroloba than on P. boryana, implying that they are more sensitive to acidification. These effects were worsened when photosynthesis was inhibited by 3-(3,4-dichlorophenyl)-1,1-dimethylurea, highlighting the significance of photosynthetic electron transport-dependent processes. Our findings suggest that estimations of the amount of carbon stored in the vegetated marine ecosystems should account for macroalgal calcification as a potential carbon source while considering diurnal variations in photosynthesis and seawater pH in a natural setting

Photosynthetic Responses of Freshwater Macrophytes to the Daily Light Cycle in Songkhla Lagoon

Macrophytes play an important role in the freshwater ecosystem. However, human activities and climate change are currently affecting aquatic lakes and species in various ways. The heterogeneity of macrophyte ecophysiology might lead to different responses to changing environments. To understand the photosynthetic responses of freshwater macrophytes to changes in light, six freshwater macrophyte species from Songkhla Lagoon were investigated. The results showed that there was a diurnal response of photosynthetic activities in all species. The Fv/Fm and ∆F/Fm′ of all species decreased at midday (9 a.m.–3 p.m.) then recovered at 6 p.m. close to the 6 a.m. level. As well as alpha, the positive relation between alpha and light showed the adaptation of plants. The saturating irradiance (Ik) revealed that plants from different light regimes showed different responses to light and temperature changes. To maintain a positive carbon balance and cope with light and temperature conditions, macrophytes had strategies such as modifying light harvesting capacity and light use. This study provides a better understanding of the vulnerability of each species to environmental changes and photosynthetic responses that enable species from different light regime to adapt to changing light environments

Contribution of Community-Managed Sal-Based Forest in Climate Change Adaptation and Mitigation: A Case from Nepal

Forests are viable tools in combating the impacts of climate change, as they are capable of sequestering atmospheric carbon and storing it in different pools. This study aimed to examine the carbon sequestration potential of community-managed Shorea robusta (Sal) forest and assess the practices that have the potential to reduce adverse climate change impacts, thereby improving the livelihoods of forest-based communities. For this, we obtained forest inventory-derived carbon data from 11 sample plots of Shorea robusta (Sal) forest, analyzed them using allometric equations, and estimated the carbon storage and climate change mitigation potential of these forests, while focus group discussions and desk review of secondary information were employed to investigate the adaptation potential. The results show that the estimated biomass density of the selected forest is 352.46 ± 63.79 t/ha, whereas the carbon stock density is 165.66 ± 29.98 t/ha and the CO2 equivalent is 598.07 ± 110.48 t/ha. The study further revealed that community forest management, as a successful model of participatory forest management and community forest user group (CFUG) as a resourceful local institution, has been playing an important role in the diversification of livelihoods and income opportunities, social cohesion and thus climate change adaptation through collective actions. The adaptation and mitigation of climate change impacts have been prioritized in the operational plans of the CFUGs. Through the promotion and prioritization of alternative energy, agroforestry and enhanced livelihood options, the CFUGs are committed to the sustainable management of forest resources and to enhancing the livelihoods of local communities. This study indicates the relevance of community forests as a priority institution for the implementation of Local Adaptation Plans for Action (LAPA) and support National Adaptation Program of Action (NAPA) to combat climatic impacts, providing important information for planners and policy makers in Nepal and elsewhere

Seawater carbonate chemistry, calcification rate, oxygen production, maximum quantum yield, symbiont density, chlorophyll concentration and crystal width of Halimeda macroloba, Halimeda cylindracea and Marginopora vertebralis during experiments, 2011

The effects of elevated CO2 and temperature on photosynthesis and calcification in the calcifying algae Halimeda macroloba and Halimeda cylindracea and the symbiont-bearing benthic foraminifera Marginopora vertebralis were investigated through exposure to a combination of four temperatures (28°C, 30°C, 32°C, and 34°C) and four CO2 levels (39, 61, 101, and 203 Pa; pH 8.1, 7.9, 7.7, and 7.4, respectively). Elevated CO2 caused a profound decline in photosynthetic efficiency (FV : FM), calcification, and growth in all species. After five weeks at 34°C under all CO2 levels, all species died. Chlorophyll (Chl) a and b concentration in Halimeda spp. significantly decreased in 203 Pa, 32°C and 34°C treatments, but Chl a and Chl c2 concentration in M. vertebralis was not affected by temperature alone, with significant declines in the 61, 101, and 203 Pa treatments at 28°C. Significant decreases in FV : FM in all species were found after 5 weeks of exposure to elevated CO2 (203 Pa in all temperature treatments) and temperature (32°C and 34°C in all pH treatments). The rate of oxygen production declined at 61, 101, and 203 Pa in all temperature treatments for all species. The elevated CO2 and temperature treatments greatly reduced calcification (growth and crystal size) in M. vertebralis and, to a lesser extent, in Halimeda spp. These findings indicate that 32°C and 101 Pa CO2, are the upper limits for survival of these species on Heron Island reef, and we conclude that these species will be highly vulnerable to the predicted future climate change scenarios of elevated temperature and ocean acidification

Diversity and distribution of seaweed at Khanom-Mu Ko Thale Tai National Park, Nakhon Si Thammarat Province, Thailand

Diversity and distribution of seaweeds at Khanom-Mu Ko Thale Tai National Park, Nakhon Si Thammarat Province,Thailand were carried out between October 2005 and May 2008 at five islets, Ko Taen, Ko Mut Sum, Ko Rab, Ko Wang Nai,and Ko Wang Nok. A total of 60 species were identified including 23 species of Chlorophyta, 19 species of Phaeophyceae inthe Chromophyta, 16 species of Rhodophyta, and 2 species of Cyanobacteria. Of these, eight species are believed to be newrecords for the Thai marine flora. The number of species varied from site to site. Ko Tan had the highest diversity with 49species and KoWang Nok had the lowest diversity with 22 species. This study provides a more complete species list forfurther comparative studies between the Gulf of Thailand and the Andaman Sea. We have intensively reviewed the seaweedliterature of Thailand, which was very limited. However, recent work on population and community structure have increasedfrom 2005, which helps providing a baseline for future, more complex ecological studies, as well as for coastal managementand for the exploration of the seaweed’s economic potential

Warmer more acidic conditions cause decreased productivity and calcification in subtropical coral reef sediment-dwelling calcifiers

The effects of elevated CO2 and temperature on photosynthesis and calcification in the calcifying algae Halimeda macroloba and Halimeda cylindracea and the symbiont-bearing benthic foraminifera Marginopora vertebralis were investigated through exposure to a combination of four temperatures (28°C, 30°C, 32°C, and 34°C) and four CO2 levels (39, 61, 101, and 203 Pa; pH 8.1, 7.9, 7.7, and 7.4, respectively). Elevated CO2 caused a profound decline in photosynthetic efficiency (FV : FM), calcification, and growth in all species. After five weeks at 34°C under all CO2 levels, all species died. Chlorophyll (Chl) a and b concentration in Halimeda spp. significantly decreased in 203 Pa, 32°C and 34°C treatments, but Chl a and Chl c2 concentration in M. vertebralis was not affected by temperature alone, with significant declines in the 61, 101, and 203 Pa treatments at 28°C. Significant decreases in FV : FM in all species were found after 5 weeks of exposure to elevated CO2 (203 Pa in all temperature treatments) and temperature (32°C and 34°C in all pH treatments). The rate of oxygen production declined at 61, 101, and 203 Pa in all temperature treatments for all species. The elevated CO2 and temperature treatments greatly reduced calcification (growth and crystal size) in M. vertebralis and, to a lesser extent, in Halimeda spp. These findings indicate that 32°C and 101 Pa CO2, are the upper limits for survival of these species on Heron Island reef, and we conclude that these species will be highly vulnerable to the predicted future climate change scenarios of elevated temperature and ocean acidification

Synergistic Effect of Elevated Temperature and Light Stresses on Physiology of <i>Pocillopora acuta</i> from Different Environments

Increasing levels of greenhouse gases lead to ocean warming, which affects a range of marine organisms. Corals live in a narrow temperature range and become stressed when the temperatures change. Bleaching occurs when the temperature exceeds the coral’s threshold, and can be severe when this is combined with other stressors such as light. In order to understand how temperature and light affect corals in their physiological responses and photosynthetic performance, Pocillopora acuta from Maiton Island (MT) and Panwa Cape (PW), representing different environments, were investigated. The results show that light and temperature had by regime different effects on Symbiodiniaceae photosynthesis and the coral growth rate. There was a synergistic effect of elevated temperature and light on photosynthesis, as observed in the photochemical efficiency and pigment contents, suggesting photo-damage. A higher growth rate in Panwa corals was observed in control, and while elevated temperature reduced coral growth. Elevated temperature affected the Panwa coral less, suggesting that corals from this regime might be able to recover when the temperature returns to normal. This information is important for predicting the coral responses to elevated temperature especially in the summer, as regards the possibility of coral bleaching

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