ISSN : 1225-3480
Shellfish production on the west coast Korea has been declined for the past two decades, and the parasite infection is considered to be one of the causes responsible for the decline of Manila clam Ruditapes philippinarum. In this study, we first investigated the pathologic condition of Manila clams and the Pacific oysters Crassostrea gigas in Garorim Bay on the west coast, where Manila clams and the Pacific oysters are co-cultured. Histology and Ray’s fluid thioglycollate medium assay (RFTM) revealed that most of Manila clams are infected by protozoan parasite Perkinsus olseni (98.0-100.0% prevalence). In contrast, none of the Pacific oysters diagnosed by the histology showed P. olseni in their tissue. The mean infection intensity of P. olseni in Manila clams was high, ranging from 0.796 (Ohiji-ri) to 2.058 (Dangsan-ri) × 106 cells/g wet tissue weight. In histology, metacercaria of Parvatrema duboisi was identified from the mantle tissue of Manila clam. Ancistrocoma-like ciliates (ALCs) were found from the digestive tubules of the oysters, with the prevalence ranging from 10.0 to 13.0 %. Rickettsia-like organisms (RLOs) were commonly identified from the epithelial cells of the digestive tubule of the Pacific oysters and Manila clams, with a prevalence ranging from 0.0 to 10.0% in Manila clams and 6.7 to 10.0% in the oysters. The mean condition index (CI) of Manila clams from Ohji-ri was significantly lower than CI of clams at Dangsan-ri tidal flat (ANOVA, P < 0.05). The mean digestive gland atrophy (DGA) of clams at Ohji-ri was significantly higher than the DGA of clams at Dangsan-ri (ANOVA, P < 0.05). The mean infection intensity of P. olseni in the host clams from Dangsan-ri was significantly higher than the clams in Ohji-ri (ANOVA, P < 0.05). The observed spatial variation in the CI and DGA was believed to be linked to a spatial change in the available food in the environment, although more investigations must be carried out to validate this hypothesis.
Beninger, P.G., Lucas, A. (1984) Seasonal variations in condition, reproductive activity and gross biochemical composition of two species of adult clam reared in a common habitat: Tapes decussatus L. (Jeffreys), and Tapes philippinarum (Adame & Reeve). Journal of experimental Marine Biology and Ecology, 79: 19-37.
Chang, T., Jung, B.-K., Shin, H., Hong, S., Lee, J., Kim, D.-G., Patarwut, L., Sohn, W.-M., Chai, J.-Y. (2020)Morphological and molecular confirmation of Parvatrema duboisi metacercariae in the Manila clam Ruditapes philippinarum from Gochang-gun, Korea. Korean Journal of Parasitology, 58: 87-91.
Choi, K.-S., Wilson, E.A., Lewis, D.H., Powell, E.N., Ray, S.M. (1989) The energetic cost of Perkinsus marinus parasitism in oysters: Quantification of the thioglycollate method. Journal of Shellfish Research, 8: 125-131.
Ellis, M.S., Barber, R.D., Hillman, R.E., Powell, E.N. (1998) Histopathology analysis. NOAA Technical Memorandum NOS ORCA, 130: 198-215.
Kang, D.-H., Chu, F-L.E., Yang, H.-S., Lee, C.-H., Koh, H.-B., Choi, K.-S. (2010) Growth, reproductive condition, and digestive tubule atrophy of Pacific oyster Crassostrea gigas in Gamakman Bay off the southern coast of Korea. Journal of Shellfish Research, 29: 839-845.
Kang, H.-S., Yang, H.-S., Reece, K.S., Cho, Y.-G., Lee, H.-M., Kim, C.-W., Choi, K.-S. (2017) Survey on Perkinsus species in Manila clam Ruditapes philippinarum in Korean waters using speciesspecific PCR. Fish Pathology, 52: 202-205.
Kang, H.-S., Itoh, N., Limpanont, Y., Lee, H.-M., Whang, I., Choi, K.-S. (2019) A novel paramyxean parasite, Marteilia tapetis sp. nov. (Cercozoa) infecting the digestive gland of Manila clam Ruditapes philippinarum from the southeast coast of Korea. Journal of Invertebrate Pathology, 163: 86-93.
Le, T.C., Kang, H.-S., Hong, H.-K., Park, K.-J., Choi, K.-S. (2015) First report of Urosporidium sp., a haplosporidian hyperparasite infecting digenean trematode Parvatrema duboisi in Manila clam, Ruditapes phlippinarum on the west coast of Korea. Journal of Invertebrate Pathology, 130: 141-146.
Limpanont, Y. (2010) Histopathological and biological survey on marine bivalve parasites in Korean waters (Ph.D thesis). Jeju National University, Korea, pp. 173.
Limpanont, Y., Kang, H.-S., Hong, H.-K., Jeung, H.-D., Kim, B.-K., Le, T.C., Kim, Y.-O., Choi, K.-S. (2013)Molecular and histological identification of Marteilioides infection in Suminoe oyster Crassostrea ariakensis, Manila clam Ruditapes philippinarum and Pacific oyster Crassostrea gigas on the south coast of Korea. Journal of Invertebrate Pathology, 114: 277-284.
Mondol, M.R., Keshavmurthy, S., Lee, H.-J., Hong, H.-K., Park, H.-S., Park, S.-R., Kang, C.-K., Choi, K.-S. (2015) Recovery of wild Pacific oysters, Crassostrea gigas in terms of reproduction and gametogenesis two-years after the Hebei Spirit oil spill accident off the west coast of Korea. Continental Shelf Research, 111: 333-341.
Mondol, M.R., Kim, C.-W., Kim, B.-K., Kang, C.-K., Choi, K.-S. (2012) Early growth and reproduction of hatchery-produced Pacific oyster Crassostrea gigas in Gamakman Bay off the southern coast of Korea. Fisheries Science, 78: 1285-1292.
Nam, K.-W., Jeung, H.-D., Song, J.-H., Park, K.-H., Choi, K.-S., Park, K.-I. (2018) High parasite burden increases the surfacing and mortality of the Manila clam (Ruditapes philippinarum) in intertidal sandy mudflats on the west coast of Korea during hot summer. Parasites & Vectors, 11: 1-7.
Ngo, T.T.T., Choi, K.-S. (2004) Seasonal changes of Perkinsus and Cercaria infections in the Manila clam Ruditapes philippinarum from Jeju, Korea. Aquaculture, 239: 57-68.
Park, K.-I., Choi, K.-S. (2004) Application of enzyme-linked immunosorbent assay for studying of reproduction in the Manila clam Ruditapes philippinarum (Mollusca: Bivalvia) Ⅰ. Quantifying eggs. Aquaculture, 241: 667-687.
Park, K.-I., Figueras, A., Choi, K.-S. (2006) Application of enzyme-linked immunosorbent assay (ELISA) for the study of reproduction in the Manila clam Ruditapes philippinarum (Mollusca: Bivalvia): Ⅱ. Impacts of Perkinsus olseni on clam reproduction. Aquaculture, 251: 182-191.
Park, K.-I., Park, J.-K., Lee, J., Choi, K.-S. (2005) Use of molecular markers for species identification of Korean Perkinsus sp. isolated from Manila clams Ruditapes philippinarum. Diseases of Aquatic Organisms, 66: 255-263.
Park, K.-J., Yang, H.-S., Jeung, H.-D., Choi, K.-S. (2013)Pathologic condition of the stranded Manila clam Ruditapes philippinarum by storm-originated sediment erosion in spring 2007 in Incheon Bay off the west coast of Korea. The Korean Journal of Malacology, 29: 147-154.
Park, K.-J., Kim, S.-K., Kang, D.-Y., Song, J.-H. (2015)Oil spill of Hebei spirit and change of Manila clam, Ruditapes philippinarum beds in the west coast of Korea. The Korean Journal of Malacology, 31:213-220.
Ray, S.M. (1966) A review of the culture method for detecting Dermocystidium marinum with suggested modifications and precautions. Proceedings of the National Shellfisheries Association, 54: 55-69.
Sohn, W.-M, Na, B.-K., Cho, S.-H., Lee, W.-J. (2017)Prevalence and density of digenetic trematode metacercariae in clams and oysters from western coastal regions of the Republic of Korea. The Korean Journal of Parasitology, 55: 399-408.
Umeda, K., Shimokawa J., Yoshinaga, T. (2013) Effects of temperature and salinity on the in vitro proliferation of trophozoites and the development of zoosporangia in Perkinsus olseni and P. honshuensis, both infecting Manila clam. Fish Pathology, 48:13-16.
Waki, T., Takahashi, M., Eki, T., Hiasa, M., Umeda, K., Karakawa, N., Yoshinaga, T. (2018) Impact of Perkinsus olseni infection on a wild population of Manila clam Ruditapes philippinarum in Ariake Bay, Japan. Journal of Invertebrate Pathology, 153:134-144.
Waki, T., Yoshinaga, T. (2015) Suppressive effects of low salinity and low temperature on in-vivo propagation of the protozoan Perkinsus olseni in Manila clam. Fish Pathology, 50: 16-22.
Yang, H.-S., Park, K.-I., Donaghy, L., Adhya, M., Choi, K.-S. (2012) Temporal variation of Perkinsus olseni infection intensity in the Manila clam Ruditapes philippinarum in Gomso Bay, off the west coast of Korea. Journal of Shellfish Research, 31: 685-690.
