• The Korean Journal of Malacology
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• v.31 no.1
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• pp.49-59
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• 2015

Eight species of the family Bithyniidae, Bithynia striatula, B. tentaculata, B. siamensis, B. leachi, B. kiusiuensis, B. misella, Bithynia sp. from Nepal, and Gabbia australis were studied for comparison of the radula structure by scanning electron microscope. Radular ribbons of B. siamensis and B. leachi had 60-70 rows, and the other species had 40-50 rows. Teeth of all species studied had symmetrical structure, i.e. a total of seven teeth (one central tooth, and one lateral and two pairs of marginal teeth on each side) in each row were observed. The basic tooth formula of eight bithyniids was 2:1:1:1:2. Numbers and shapes of cusps were slightly differ from individuals or species. The mesocone of the central tooth of B. striatula, B. tentaculata, B. siamensis and Bithynia sp. differed from those of the other species observed.

• The Korean Journal of Malacology
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• v.10 no.1
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• pp.19-26
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• 1994

Eight species of the family Bithyniidae, Bithynia tentaculata, B. leachi, B. siaminsis, B manchourica, B misella, B. kiusiuensis, Gabbia australis and a Bithynia wp. collected from Nepal, were studied for their relationship between species. Total 20 characters were employed for the principal component analysis(PCA) and taxonomic distance. G. misella and B. kiusiuensis were closely related and similar to G. australis. B. manchourica, B. tentaculata and B. siamensis relatively closed group, and taxonomic distance of B. leachi was far from the other species.

• The Korean Journal of Malacology
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• v.21 no.2 s.34
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• pp.133-145
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• 2005

Eight species of bithyniids, Bithynia leachi, B. tentaculata, B. siamensis, B. misella, B. kiusiuensis, B. striatula, Bithynia sp. from Nepal and Gabbia australis were collected from 1957 to 1988. The samples were relaxed with pentobarbital and fixed with 70% ethyl alcohol. There was no significant difference in internal structure of soft body, except the male reproductive system. The alimentary canal of the bithyniids consisted of mouth, buccal mass, esophagus, stomach, intestine, rectum and anus. The heart consisted of an auricle and a ventricle, located at left side of the stomach in the visceral hump. The ctenidium comprised 40-70 subtriangular lamellae. Eight ganglia were located around upper esophagus. The female reproductive system comprised ovary, oviduct, spermaaheca, and albumin gland. The male reproductive system was composed of testis, seminal vesicle, prostate gland, vas deferens, penial duct, and penis in order. Male was distinguished externally from the female by a bifid penis.

• Korean Journal of Environmental Biology
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• v.23 no.2 s.58
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• pp.106-113
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• 2005

This study was conducted to examine the community structure of macrobenthos on Angel tidal flat in Jinhae, south coast of Korea. Monthly samples were conducted at eight sites from March 1998 to February 1999. A total of 110 species were sampled with a mean density of 322ind. $m^{-2}$ and biomass of 98.4 wwt g $m^{-2}$. Of these species, there were 44 species of polychaetes $(40.0\%)$, 41 species of crustaceans $(37.3\%)$ and 16 species of molluscs $(14.5\%)$. The major density dominant species were a gastropod Batilaria cumingi (52ind. $m^{-2}$) and five polychaetes Ceratonereis erythraeensis (38ind. $m^{-2}$), Cirriformia tentaculata (32ind. $m^{-2}$), Capitella capitata (23ind. $m^{-2}$), Sigambra tentaculata (23ind. $m^{-2}$), Glycera chirori (17ind. $m^{-2}$). Cluster and MDS analysis showed that the study sites could be divided into two tidal elevation groups. According to the spatial distribution of dominant species and SIMPER analysis, the two groups were characterized by Sigambra tentaculata - Chaetozone setosa in upper species group and Ceratonereis erythraeensis-Cirriformia tentaculata-Capitella capitata in lower species group.

• The Korean Journal of Malacology
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• v.1 no.1
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• pp.24-50
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• 1985

Five different populations of Parafossarulus manchouricus (Chongpyung, Chinju and Kunsan, Korea; and Japan and Taiwan), a population of Bitbynia (Gabbia) misella (Gongju, Korea) and two different populations of Bithynta tentaculata (Michigan, U.S.A. and Bodensee, Germany) were compared in regard to eff-laying characteristics, morphology, chromosome cytology, natural infections of parasites and ecology of habitats. A satisfactory culture method was devised for laboratory rearing of the snails. Tropical fish food (Terra SML) and powdered green leaves (Ceralife) were used as the main food sources for the snails. Benthic diatoms such as Navicula and Gomphonema from the periphyton were also essential for satisfactory growth, especially for the baby snails. The aquaria were stabilized with small stones from a local stream. Young P. manchouricus snails grew to adult size in about 54 days after hatching. They laid eggs 150-156 days after hatching. The whole cycle (birth to egg-laying) took approximately 5 months. The three species of bithyniid snails are iteroparous and lay eggs once a year. There were no major morphological differences in the shells of genera or subgenera studied here. They did exhibit the following rather minor differences. The shell of Parafossarulus has spirally raised ridges, and its apex is usually eroded; the other two genera lack these characteristics. The shell of B. (Gabbia) misella is small, nor exceeding 7.5 mm in length, while the shells of the other two species are larger, being more than 10 mm in length. Scanning electron microscopy (SEM) of the protoconch of P. manchouricus reveals nearly smooth sculpture with small, low, spiral wrinkles. This sculpture is quite different from that of the Hydrobiidae, a family to which the bithyniids are frequently assigned. Scanning electron microscopy of the radulae of the three bithyniid species showed that their radular morphologies are very similar, but there are some small differences, which may be species-specific. There were some statistical differences in shell heights between the Korean and the other populations of P. manchouricus, and between this species and the other two bithyniids as well. The shell differences between the several populations of Korean P. manchouricus may be related to environment. Edtails of the chromosome cycle of these bithyniid snails are similar to those reported for other snails. No specific differences were observed in the chromosome cycle between the various species and populations of snails employed in this study. Reporred for the first time in molluscs are two darkly stained "nucleolar organizers" during pachyterne stages of meiosis. Two different chromosome numbers were observed in the three bithyniid species: n=17 in B. tentaculata and P. manchouricus, and n=18 in B. (G.) misella. no sex chromosomes or supernumerary chromosomes were seen. There were no morphological differences in karyotypes of three Korean strains of P. manchouricus. The infection rates of cercariae of Clonorchis sinensis in Chinju and Kunsan strains of P. manchouricus were 0.14% and 1.25%, respectively. However, Clonorchis cercariae were found in Chongpyung strain of P. manchouriceu and Gongju strain of B. (G.) misella. The habitats of P. manchouricus around Jinyang Lake were relatively clean without any heavy pollution of aquatic microorganisms and organic materials during the period of this study. The levels of dissolved oxygen (D.O.) and biochemical oxygen demand (B.O.D.) of the water specimens sampled from the study areas ranged from 6.0 to 9.6 ppm and from 0.4 to 1.6 ppm, respectively. Eight metalic constituents from the water samples were also assayed, and all metalic ions detercted were remarkably low below the legal criteria. However, calcium ion in the water samples from the habitats of P. manchouricus was considerably higher than others.

• The Korean Journal of Malacology
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• v.5 no.1
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• pp.42-56
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• 1989

Shells and operculums of eight species of Bithyniidae, Bithynia leachi, B. tentaculata, B. siamensis, B. misella, B. kiusiuensis, Gabbia australis, B. manchourica and a Bithynia sp. collected from Nepal, were observed, There is no morphological difference between korean populations of B. misella and a Japanese popualtion of B. kiusiuensis. And the shells of these species were simialr to the other Bithynia species rather than Australian Gabbia. The coordinate of the starting point of nuclear spire of operculum(SPN)was species specific and this value had very limited range within a species. The result suggested that Korean and Japanese populations of B. misella and B. kiusiuensis are synonym and the coordinate of SPN will be a useful character in sytematics of operculated snails.

• Ocean and Polar Research
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• v.42 no.3
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• pp.233-247
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• 2020

This study was carried out at 5 sites 11 times over two years to identify the variation of benthic environments and benthic polychaetous community and analyze the benthic healthiness in Dangdong Bay, a small semi-enclosed inner bay of Jinhae Bay. The temperature of bottom water showed the typical temporal fluctuation of a temperate zone and was in the range of 5.94 ~ 23.94℃. The salinity did not change significantly during the study period and was in the range of 32.93 ~ 35.72 psu. The concentration of dissolved oxygen of bottom water fluctuated a great deal and was in the range of 0.31 ~ 10.20 mg/L. The lowest DO value was recorded in July 2015, as 0.31±0.04 mg/L corresponding to the hypoxic water mass. The hypoxic water mass was formed continuously at some sites also in July and August 2016. The mean grain size was in the range of 7.57 ~ 9.81Ø and the average was 8.89±0.20Ø. The surface sediments were mainly composed of fine sediment (mud) above 85%. The mean of TOC was 3.09±0.22% and LOI was 13.30±0.47%, showing very high levels in Korean coastal waters. The concentration of AVS was in the range of 0.33 ~ 1.28 mgS/g-dry. The high values of organic contents and AVS indicated that there had been the serious organic enrichment in Dangdong Bay. The number of species and the density of the benthic polychaetous community in Dangdong Bay were in the range of 2 ~ 38 species and 2 ~ 2,185 ind./㎡ during the study period. The number of species and density were highly sustained in winter and spring, and then decreased gradually with the formation of a hypoxic water mass in summer, and the lowest number of species and density were recorded in autumn. In September and November 2015, the dead zone expanded to almost the whole study area. Dominant polychaetous species were Capitella capitata, Lumbrineris longifolia, Paraprionospio patiens and Sigambra tentaculata, each known as opportunistic species and potential organic pollutant indicator species. In particular, Paraprionospio patiens showed a very high population density of 2,019 ind./㎡ in December 2016. Polychaetous communities at each sampling time were classified into 4 temporal groups according to dominant species in each period by cluster analysis and nMDS. 'Period Group AI' was formed in winter and spring of 2015, dominated by Capitella capitata, 'Period AII' in summer dominated by Lumbrineris longifolia, 'Period B' in autumn with no fauna in the dead zone, and particularly 'Period C' in winter of 2016 dominated by Paraprionospio patiens. As a result of analysis of benthic healthiness, the study area was estimated to be in a Fair~Very Poor condition by AMBI and in a Poor~Very Poor condition by BPI during the study period. Both AMBI and BPI showed that the study area was in a Very Poor condition in September and November 2015, and when the dead zone occurred. In Dongdong Bay, the fact that the formation of a hypoxic water mass occurred in summer and a dead zone in autumn were confirmed. In addition, the dominance of opportunistic and organic pollutant indicator species was also observed clearly. The benthic healthiness indexes such as AMBI and BPI showed that organic enrichment was serious in Dangdong Bay.