Pichan Sawangwong

Optimization of diet and culture environment for larvae and juvenile freshwater pearl mussels, Hyriopsis (Limnoscapha) myersiana Lea, 1856

Summary Culture of the freshwater pearl mussel, Hyriopsis (Limnoscapha) myersiana, was carried out in three consecutive steps: (1) culture of glochidia larvae in artificial media, (2) rearing the early juveniles (0–120 days old) in a nursery, and (3) rearing the juveniles (120–360 days old) in an earthen pond. The percentage survival of glochidia in standard tissue culture medium (M199) supplemented with common carp plasma was 95±2.5. All surviving larvae (100%) transformed to juveniles, the duration of transformation being 8 days. The early juveniles (0–60 days old) were fed with a mixture of four selected phytoplankton species (Chlorella sp., Kirchneriella incurvata, Navicula sp. and Coccomyxa sp.). The survival rate of juveniles was 8±0.2%. The average length of these juveniles increased from 0.13±0.01 mm to 1.41±0.16 mm and the average height from 0.16±0.01 mm to 0.98±0.09 mm. Subsequently, 60–120-day juveniles were fed with one of the same four phytoplankton species or a combination of the four. Feeding the juveniles with K. incurvata resulted in the highest survival rate (65±8.32%), with an average length of 3.46±0.04 mm and an average height of 1.94±0.04 mm. Finally, the 120–360-day juveniles were cultured in an earthen pond. There were progressive changes in average weight (0.0037±0.002 g to 11.24±5.02 g), length (3.48±0.39 mm to 54.08±6.21 mm), height (1.97±0.24 mm to 25.09±2.48 mm) and width (0.98±0.06 mm to 12.28±3.21 mm) from 120 to 360 days. The average growth rates per day of these parameters were 0.0497±0.01 g, 0.2414±0.15 mm, 0.0975±0.08 mm and 0.0493±0.03 mm, respectively. H. (L.) myersiana juveniles developed the complete structural composition of the adult by 160 days, and at 360 days, gametogenesis was complete.

Organic and inorganic compound variations in haemolymph, epidermal tissue and cuticle over the molt cycle in Scylla serrata (Decapoda)

Analysis of organic and inorganic compounds in haemolymph, epidermal tissue and cuticle, allowed the correlation of their content variation during the molt cycle in Scylla serrata (Decapoda). The extrusion of carbohydrate, chitin, H(2)O- and NaOH-soluble proteins of the epidermal tissue from D2 stage on suggested an early formation of the organic fraction in the new cuticle. The additional secretion of HCl-soluble protein, glycosaminoglycans, calcium, phosphorus and sulfur in D2-D3 stages suggests mineral nucleation shortly before or at ecdysis. This is consistent with the dominant content of proteins and chitin associated with peaks of carbohydrates and GAG-sulfur groups detected in the cuticle immediately after ecdysis. Furthermore, the maximal phosphorus content at this moment suggests calcium, magnesium and manganese phosphate deposits. After an intense accumulation of calcium, chitin and sharp decrease of protein from A to B stages, a constant rate of their deposition in intermolt and dissolution in premolt occurred. The variations concerning proteins, carbohydrates, glycosaminoglycans, calcium, magnesium and sulfur in the haemolymph, before and after ecdysis, suggest a transitory phenomenon for calcium binding and releasing. Other major elements such as, sodium, potassium and chloride may function as osmotic regulators in the haemolymph and in epidermal compartments. The copper profile presented an indicator role for variations of osmolality over the molt cycle.

Seasonal Variations in Inorganic Nutrient Budgets of the Bangpakong Estuary, Thailand

Seasonal variations in freshwater, salt, dissolved inorganic phosphorus (DIP) and dissolved inorganic nitrogen (DIN) in the Bangpakong estuary, Thailand were investigated by employing the database obtained in the National Research Council of Thailand (NRCT)-Japan Society for the Promotion of Science (JSPS) cooperative project from 1994 to 1997. The results showed that variation in interaction between coastal sea and river discharge played an important role in controlling the characteristics of the water in the estuary. Residence time of fresh water was short in wet season and dry season, but it was long in the transition period from season to season. DIP and DIN load depended on river discharge, while high peak concentrations were related to loading and the long residence time in the transition period between dry and wet seasons. A strong eutrophic condition could possibly occur when the concentration of DIP and DIN were high during the onset of the wet season from April to July. The annual average of inorganic nutrient budgets indicated that the Bangpakong estuary is the internal source of 38.2 tons/month DIP and the internal sink of 4.9 tons/month DIN.

Morphological development of the juvenile through to the adult in the freshwater pearl mussel, Hyriopsis (Limnoscapha) myersiana, under artificial culture

Summary The morphological development of the freshwater mussel, Hyriopsis (Limnoscapha) myersiana (Lea, 1856), was observed using light and scanning electron microscopes, from the newly transformed (0 days old) juvenile to the onset of the adult stage (360 days old). As in the glochidium, the early juvenile has a semi-oval and equivalve shell with an equilateral valve. After day 1 the shell develops a larger anterior than posterior region until day 40, after which the posterior region grows larger than the anterior region. The form of the juvenile at 260-day-old resembles that of a fully grown adult. The shell microstructure of 0–20-day-old juveniles shows two differentiated layers, the periostracum and the prismatic layer. By day 30 the prismatic layer lies under a clear columnar structure that has formed a third layer, the nacreous layer. The mantle develops incurrent and excurrent siphons when juveniles are 60 days old. The development of juvenile gills initiates from a pair of gill bars at 0 days old, and formation of the inner demibranch starts from 10 days old and the outer demibranch from 90 days old. From this stage, numerous cilia form the latero-frontal cirri of the inner demibranchs. Additionally, longitudinal and transversal interfilamentous junctions of the inner and outer demibranchs begin to develop when juveniles are 200 and 240 days old and are complete at 230 and 260 days of age, respectively. Interlamellar septa join the inner surface of descending and ascending gill filaments to form water chambers when juveniles are 250 and 280 days old, respectively, and the development of inner and outer demibranchs is complete.

Further Halotyrosine Derivatives from the Marine Sponge Suberea aff. praetensa

Reexamination of the marine sponge Suberea aff. praetensa, (Row) from the Gulf of Thailand furnished in addition to bromotyrosine derivatives found previously 5-bromo- and 5- chlorocavernicolin, cavernicolins 1 and 2, two other brominated tyrosine metabolites, a known bisoxazolidone and a new unusual rearranged tyrosine metabolite subereatensin. Several of the metabolites exhibited significant inhibitory effects against five human cancer cell lines.

Model of Environmental Problems Priority Arising from the Use of Environmental and Natural Resources in Construction Material Sectors of Thailand

The factors used to calculate the Forward Linkage, Backward Linkage and Real Benefit are the Total Environmental Costs. The highest total environmental cost was Iron and Steel that needs to be resolved immediately because it uses natural resources over the carrying capacity, higher environmental cost than standard, and contributes low real benefit. Iron and Steel, secondary steel products and non-residential building construction need to be monitored closely because they are able to link to other production sectors more than other production sectors, and they have high environmental cost. To design the sustainable development strategy of the country, therefore, need to use the information in this research to support the decision.

137Cs Adsorption and Desorption on Marine Sediments from the Upper Gulf of Thailand

Sediments play an important role on fate in the diffusion of radionuclide in aquatic systems. In this study, the investigation of the adsorption/desorption kinetic of 137Cs in two different characteristic of marine sediment samples (organic matter, CEC, and clay content). Batch experiment was carried out from the Upper of Gulf Thailand. The results have shown that there is a significant percentage of 137Cs is adsorbed in both marine sediments during the first 48 hour that increased adsorption percentage to 82 and 86% and after that become to stable. On the other hand, the desorption of 137Cs was found both marine sediment were desorbed less than 10 % and become to stable desorption after 24 hours. Among different marine sediments (St.1 and St.21), the Kd value (distribution coefficients) of 137Cs was different which Kd of sediment from station 1 more than station 21(342.9 and 247.5 L/kg respectively). Differences in the characteristics of marine sediments affect to different the Kd value.