Hematological evaluation of fish is essential to the assessment of their physiological status. Th... more Hematological evaluation of fish is essential to the assessment of their physiological status. This study describes the morphometric analysis and comparison of blood cell characteristics in Zanarchopterus sp., Gerres filamentosus Cuvier, 1829 and Leiognathus decorus (De Vis, 1884). The species were collected at two locations off the coast of Trang Province, Thailand. A comparative hematological evaluation was made to assess the effects of environmental conditions on the blood of the fish. Ten individuals of each species were collected from a seagrass bed at Libong Island, where human activities are increasing, and from a secluded sandy beach. Their blood samples were analysed using the blood smear technique. Erythrocytes of all the studied fishes were either elliptical or oval. The morphometric data from both locations showed that erythrocytes were of similar size, except for those of Zanarchopterus sp. Fish from both stations showed several types of leukocytes, including neutrophil...
Background: The reproductive histology in the decapods have been widely documented; however, this... more Background: The reproductive histology in the decapods have been widely documented; however, this information has never been reported in Emerita taiwanesis, one of profitable species for aquaculture business in Southeast Asia. Material and Methods: The gametogenic maturation and embryonic development of sand crabs E. taiwanesis with carapace widths of 4-5 cm (n = 20 for each sex) from Sangchan Beach, Thailand were examined by histological techniques and light microscopy. Results: The gonadal structure was located underneath the carapace at dorsal area of the body. Under histological techniques, the ovarian maturation was observed to be enclosed with a thin layer of ovarian wall. The different phases of developing oocytes could be classified into five stages: 1) Oc1 (previtellogenic stage), 2) Oc2 (early vitellogenic stages), 3) Oc3 (late vitellogenic stage), Oc4 (mature oocyte) and Oc5 (atretic oocyte). The spermatogenic maturation occurred at the same time as female ovarian maturation. The spermatogenic stage was clearly divided into five stages: spermatogonia, primary spermatocytes, secondary spermatocytes, spermatids, and spermatozoa. Additionally, different timing of its embryonic development was observed, and the embryos could be categorized into three major stages: 1) early development (cleavage, blastula, and gastrula), 2) early organogenesis (post-gastrula) and 3) late organogenesis. Conclusion: In this study, histological observation of oogenesis and spermatogenesis as well as embryogenesis of sand crab E. taiwanesis highlights the conserved pattern of gametogenic maturation among decapod, which can lead to understanding of the reproductive cycle, physiology, and aquaculture strategies of this economically important crustacean in the Gulf of Thailand.
This work investigates the ontogenetic development of the main digestive enzymes and elemental co... more This work investigates the ontogenetic development of the main digestive enzymes and elemental composition of sesarmid crab Episesarma singaporense. All observed digestive enzyme activity changed significantly with the developmental stages. The lowest pepsin-specific activity appeared in fertilized eggs (FE), then increased dramatically and maintained level during the zoeal stages, and decreased significantly in megalopa and crab I. The highest activity of trypsin and chymotrypsin were observed in FE and crab I, and the trend was increasing with age during zoeal stages. Amylase-specific activity remained about constant from FE until zoea II, dramatically increased from zoea III to zoea IV, and then decreased in the megalopal stage of newly hatched crabs. The lowest lipase-specific activity was in FE and zoea I, but increased dramatically and was maintained during zoea II to zoea IV. Significantly decreased activity was observed in megalopa relative to the maximum value in zoea III, and then the activity was regained in crab I stage. These changes were also associated with elemental composition in terms of carbon (C), hydrogen (H), nitrogen (N) and the C:N ratio. Overall findings from the current study inform about the physiological adaptations during early development, and could support the design of feeding regimens for larviculture of this species.
The health status of the zebra-snout seahorse, Hippocampus barbouri in captivity has been require... more The health status of the zebra-snout seahorse, Hippocampus barbouri in captivity has been required for approval for aquaculture. In this study, we investigated the histopathological appearance of three vital organs including gill, kidney and liver in captive H. barbouri during its juvenile and adult stages, by using histological techniques. In juveniles from stage 14-days (100% prevalence) towards stage 30-days adults (100% prevalence), the gills exhibited intraepithelial edema and necrosis while hepatic tissue showed evidence of intracytoplasmic vacuoles. In addition, histological alteration to renal tissues was observed the degeneration of renal tubules, the presence of melanomacrophage, and the infection of trematode parasites. The parasites were found in stage 30-days adult fish in the kidney (33.3 % prevalence). Taken together, this study highlights the issue of health in captive rearing of H. barbouri, in particular histopathological alterations in gill, liver and kidney tissu...
Hematological evaluation of fish is essential to the assessment of their physiological status. Th... more Hematological evaluation of fish is essential to the assessment of their physiological status. This study describes the morphometric analysis and comparison of blood cell characteristics in Zanarchopterus sp., Gerres filamentosus Cuvier, 1829 and Leiognathus decorus (De Vis, 1884). The species were collected at two locations off the coast of Trang Province, Thailand. A comparative hematological evaluation was made to assess the effects of environmental conditions on the blood of the fish. Ten individuals of each species were collected from a seagrass bed at Libong Island, where human activities are increasing, and from a secluded sandy beach. Their blood samples were analysed using the blood smear technique. Erythrocytes of all the studied fishes were either elliptical or oval. The morphometric data from both locations showed that erythrocytes were of similar size, except for those of Zanarchopterus sp. Fish from both stations showed several types of leukocytes, including neutrophil...
Background: The reproductive histology in the decapods have been widely documented; however, this... more Background: The reproductive histology in the decapods have been widely documented; however, this information has never been reported in Emerita taiwanesis, one of profitable species for aquaculture business in Southeast Asia. Material and Methods: The gametogenic maturation and embryonic development of sand crabs E. taiwanesis with carapace widths of 4-5 cm (n = 20 for each sex) from Sangchan Beach, Thailand were examined by histological techniques and light microscopy. Results: The gonadal structure was located underneath the carapace at dorsal area of the body. Under histological techniques, the ovarian maturation was observed to be enclosed with a thin layer of ovarian wall. The different phases of developing oocytes could be classified into five stages: 1) Oc1 (previtellogenic stage), 2) Oc2 (early vitellogenic stages), 3) Oc3 (late vitellogenic stage), Oc4 (mature oocyte) and Oc5 (atretic oocyte). The spermatogenic maturation occurred at the same time as female ovarian maturation. The spermatogenic stage was clearly divided into five stages: spermatogonia, primary spermatocytes, secondary spermatocytes, spermatids, and spermatozoa. Additionally, different timing of its embryonic development was observed, and the embryos could be categorized into three major stages: 1) early development (cleavage, blastula, and gastrula), 2) early organogenesis (post-gastrula) and 3) late organogenesis. Conclusion: In this study, histological observation of oogenesis and spermatogenesis as well as embryogenesis of sand crab E. taiwanesis highlights the conserved pattern of gametogenic maturation among decapod, which can lead to understanding of the reproductive cycle, physiology, and aquaculture strategies of this economically important crustacean in the Gulf of Thailand.
This work investigates the ontogenetic development of the main digestive enzymes and elemental co... more This work investigates the ontogenetic development of the main digestive enzymes and elemental composition of sesarmid crab Episesarma singaporense. All observed digestive enzyme activity changed significantly with the developmental stages. The lowest pepsin-specific activity appeared in fertilized eggs (FE), then increased dramatically and maintained level during the zoeal stages, and decreased significantly in megalopa and crab I. The highest activity of trypsin and chymotrypsin were observed in FE and crab I, and the trend was increasing with age during zoeal stages. Amylase-specific activity remained about constant from FE until zoea II, dramatically increased from zoea III to zoea IV, and then decreased in the megalopal stage of newly hatched crabs. The lowest lipase-specific activity was in FE and zoea I, but increased dramatically and was maintained during zoea II to zoea IV. Significantly decreased activity was observed in megalopa relative to the maximum value in zoea III, and then the activity was regained in crab I stage. These changes were also associated with elemental composition in terms of carbon (C), hydrogen (H), nitrogen (N) and the C:N ratio. Overall findings from the current study inform about the physiological adaptations during early development, and could support the design of feeding regimens for larviculture of this species.
The health status of the zebra-snout seahorse, Hippocampus barbouri in captivity has been require... more The health status of the zebra-snout seahorse, Hippocampus barbouri in captivity has been required for approval for aquaculture. In this study, we investigated the histopathological appearance of three vital organs including gill, kidney and liver in captive H. barbouri during its juvenile and adult stages, by using histological techniques. In juveniles from stage 14-days (100% prevalence) towards stage 30-days adults (100% prevalence), the gills exhibited intraepithelial edema and necrosis while hepatic tissue showed evidence of intracytoplasmic vacuoles. In addition, histological alteration to renal tissues was observed the degeneration of renal tubules, the presence of melanomacrophage, and the infection of trematode parasites. The parasites were found in stage 30-days adult fish in the kidney (33.3 % prevalence). Taken together, this study highlights the issue of health in captive rearing of H. barbouri, in particular histopathological alterations in gill, liver and kidney tissu...
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