Marsh Clam Research Articles

Removal of Phosphorus from Water onto Marsh Clam Shell to Predict Contour for Removal Efficiency and Mass of Adsorbent

Anthropogenic activities have resulted in considerable water quality degradation in water sources due to a common problem of the excessive nutrient content (phosphorus) in receiving water, resulting in eutrophication. Even though various wastewater treatment methods have been applied, focusing on phosphorus removal through biological, physical, and chemical treatment, there is still a need to identify the eco-friendly method using the adsorption process and verify the theoretical and experimental data via kinetic and isotherm models. Hence, this study investigates phosphorus removal efficiency from water onto raw marsh clam shells and verifies the experimental and theoretical data with kinetic and isotherm studies. The variable of this study used different masses (2, 4, 6, 8, 10 g) of adsorbents with particle sizes from 1.18 mm to 2.36 mm to remove phosphorus from an aqueous solution (5 mg/L). The physicalchemical properties of adsorbents were examined using X-ray diffraction (XRD), scanning electron microscopy (SEM), Energy Dispersive X-ray Fluorescence (EDXRF), and Fourier Transform Infrared Spectroscopy (FTIR) to support the experimental data and identify the possibility of phosphorus adsorption. The batch experiment data obtained were verified using the kinetic (pseudo-first-order and pseudo-second-order) and isotherm (Langmuir and Freundlich) models. The experiments showed that the best contact time for all masses was 1440 min and the best adsorbent dose was 10 g with 78.0%removal. By comparing the two adsorption isotherm models, the study finds that the adsorption isotherm fits the Langmuir isotherm model with a correlation coefficient, R<sup>2</sup> of 0.9006. The novel use of adsorbent marsh clam shell as a potential adsorbent in the application of future water treatment technologies.

Experimental investigations on sustainable mortar containing recycled seashell powder as cement partial replacement

Creating sustainable mortar containing recycled seashells is an innovative approach that can contribute to environmental conservation and reduce waste. The use of seashells as a partial replacement for traditional raw materials in mortar can have several benefits, including conservation of natural resources, waste reduction, and improved material properties. The current study uses Marsh Clam seashells after crushing the cleaned seashells into powder. Heated ( up to 600C°) and unheated seashells were considered in the experimental investigation. In both batches, a seashell powder (heated and unheated) was replaced with OPC cement in proportions of 6, 9 and 12% in the mixing process. XRD, SEM, EDS and mechanical tests were employed to determine the crystal structure and to provide a comprehensive understanding of the physical, chemical, and structural characteristics of the substance. The study concluded that the calcium carbonate (CaCO3) that is nature chemical form of seashells was turned to calcium oxide (CaO) during the heating process and the resulted product was highly reactive with water, improved microstructural properties of the concrete. It also promotes better particle packing, reduce porosity, and create a denser, more uniform concrete matrix and enhancing the overall performance of the material.

Effect of Various Sizes of Calcined Marsh Clam Shell on Phosphate Removal from Aqueous Solution

Phosphorus is one of essential elements for sustaining life largely through phosphate, a compound containing the phosphate ion, PO43−. However, excessive phosphorus concentrations will cause eutrophication and this condition is considered as an environmental issue. The phosphorus sources are commonly from human activities; for instance, detergents, fertilisers, and industries. Although various adsorption techniques have been applied to remove phosphorus in water, the effect of different particle sizes of calcined marsh clam shells on phosphate removal has not been fully investigated, along with its adsorption kinetics and isotherms. This study investigates phosphate removal from synthetic solution onto calcined marsh clam shells (CMCs) with 5 different particle sizes: 0.075–0.15, 0.15–0.30, 0.30–0.60, 0.60–1.18, and 1.18–2.36 mm. The batch experiment used 2 g of adsorbent and synthetic potassium dihydrogen phosphate (KH2PO4) solution. The adsorbent size of 0.075 to 0.15 mm showed the highest removal (100%) efficiency due to high adsorption rate. The experimental data were further analysed using kinetics and isotherm models; the data fitted well with pseudo-second-order kinetic model (R2 = 0.9986) and Freundlich isotherm model (R2 = 0.8404). The potential of marsh clam shells as an adsorbent for phosphate removal in water is significant for future applications in wastewater treatment technology.

Responses of purple mud crab (Scylla tranquebarica) to various saccharide solutions and the saccharide-coated pelleted feeds

Mud crabs (Scylla spp.) are economically important portunid species for aquaculture in many countries across the Indo-Pacific region. However, there is still no commercial species-specific formulated feed available for mud crabs, and mud crabs generally reject pelleted feed and the commercial formulated feeds available for other farmed aquatic species. Therefore, diets attractability and palatability are important criteria to develop formulated feed for mud crabs. To identify the suitable chemoattractant for attracting mud crabs to the feed, and also feeding stimulant to promote feed ingestion in mud crabs, the present study examined the S. tranquebarica appetitive response towards the solutions of various saccharides (galactose, glucose, sucrose, maltose, fructose, mannose) at 1.0 M, 0.1 M, and 0.01 M in Experiment I, and also its feeding response towards the pelleted feeds, coated with the selected highly stimulative saccharides (galactose, glucose, sucrose or fructose) in Experiment II. In Experiment I, all saccharides tested were stimulative to the S. tranquebarica. At 1.0 M, galactose, glucose, and sucrose were the most stimulative saccharides, although they were not as stimulative as the marsh clam extract (positive control). The stimulative effects of galactose and glucose were not significantly reduced when they were tested at 0.1 M. In Experiment II, the pelleted feeds coated with the selected saccharides at 0.1 M were more attractive (higher mean score) to the S. tranquebarica than the control feed (without saccharide coating), but only the mean scores of galactose and sucrose were significantly higher than that of the control feed. Nevertheless, no true ingestion on any of the pelleted feeds was observed, presumably due to the non-ideal dietary inclusion method used. Based on these results, it was concluded that all the saccharides tested were potent chemoattractants to the S. tranquebarica. However, additional study is needed to further confirm that these saccharides are also feeding stimulants to the mud crab. Additional research is also required to refine the formulation and application method of these saccharides as a practical chemoattractant or feeding stimulant in the farming of Scylla mud crabs.

Analysis of Heavy Metal (Hg, Pb, Ni) Content in Marsh Clam, Polymesoda expansa Collected from Butuan Bay, Philippines

Butuan Bay is an amalgamation of resources and wastes, with the Agusan River as its main river source. Multiple industrial operations near the area make it susceptible to pollution, thereby affecting the aquatic organisms and the people who depend on the bay for food and livelihood. Thus, the main objective of the study was to determine the Mercury (Hg), Lead (Pb), and Nickel (Ni) concentration in the flesh of Marsh clam (Polymesoda expansa) in different mangroves wetlands across Butuan Bay. Heavy metal concentration was assessed using cold vapor atomic absorption spectroscopy for Hg and Atomic Absorption Spectrophotometry for Pb and Ni. The results revealed that Hg and Pb concentrations were below the detection limits (BDL), while Ni concentrations were within the tolerable limits established for bivalves. Human health risk via the consumption of P. expansa was calculated using the estimated daily intake (EDI) and Target Quotient Hazard (THQ). Results show that the EDI of Ni exceeded the oral reference dose, but its THQ was below the standard THQ value. In conclusion, the consumption of P. expansa does not pose any adverse health effects on human health. Still, further investigation and monitoring of the mangrove ecosystems are encouraged to secure the environment's health and the communities that depend on it.

Removal of Phosphate from Synthetic Wastewater by Using Marsh Clam (Polymesoda expansa) Shell as an Adsorbent

Phosphate pollution is becoming a serious problem worldwide. It leads to increased algae growth, resulting in eutrophication, which affects the water bodies’ quality, the lives of aquatic organisms, and the daily routines of humankind. Previous research has proven effective chemical precipitation for phosphate removal, but the cost is high and may generate waste material. Thus, this study proposed the marsh clam (Polymesoda expansa) shell as an absorbent due to its abundant availability, low cost, and high absorption capacity of phosphorus. This study was conducted to investigate the removal efficiency of phosphate using raw marsh clamshells. In this study, the concentration of aqueous solution using KH2PO4 was fixed to 10 mg/L of PO43− as the initial concentration. The 2 g of mass absorbent (0.075mm, 0.15mm, 0.30 mm, 0.60 mm, 1.18 mm, 2.36 mm) mixed with 100mL of KH2PO4 solution in the conical flask in a certain time interval. The orbital shaker was used for mixing the KH2PO4 solution with the adsorbent. Moreover, HACH DR 6000 Spectrophotometer is then used to determine phosphate concentration for initial and final results. The results were verified using kinetic and isotherm models, where kinetic models used Pseudo First Order (PFO) and Pseudo Second Order (PSO). The isotherm model used the Freundlich and Langmuir models. The optimum performance of the batch experiment showed by the PSO model had the highest correlation coefficient (R2 = 0.9965) and the lowest Fe value of 0.086. This study showed that marsh clamshells could remove PO43− effectively for 1.18–2.36 mm size with the highest removal efficiency of 73%. The removal of phosphate from domestic wastewater can be an alternative wastewater treatment in tertiary treatment in the field of the wastewater treatment plant.

The Lokan (Marsh Clam) Festival and the Rungus Ethnic Group Participant in Community-Based Aquaculture Program, North Borneo, Malaysia

The Lokan (Marsh Clam) Festival and the Rungus Ethnic Group Participant in Community-Based Aquaculture Program, North Borneo, Malaysia

Heavy Metals in Marsh Clam (Polymesoda expansa) as Bioindicators for Pollution in Industrial and Sand Mining Area of Kelantan River Basin, Malaysia

Industrial and sand mining activities have severely degraded the water quality of the Kelantan River, as well as the river ecosystem. However, there have been inadequate studies on the effect of industrial and sand mining on organisms in the Kelantan River. Therefore, this study assessed the concentrations of Pb, Cd, Zn and Cu in the bivalves of genus (Polymesoda expansa) marsh clams from the Kelantan River tributaries, namely the Geting River and the Semarak River, which are located near to an industrial and a sand mining area, respectively. More than 50 marsh clams were collected at these sites. Heavy metals in marsh clams were extracted using aqua regia methods and analyzed using a Flame Atomic Absorption Spectrometer (FAAS). The mean concentrations of Pb, Cd, Zn and Cu at the Semarak River were 4.61, 2.16, 194 and 6.20 mg/kg, respectively. Accordingly, the concentrations at the Geting River were 4.43, 2.50, 196 and 7.90 mg/kg, respectively. The pattern of metal concentrations within the whole tissue of marsh clams from the Geting River and the Semarak River were in the following order: Zn > Cu > Pb > Cd (concentration in mg/kg). The mean concentration of selected metals (Zn, Cd, Pb) in the studied samples exceeded the permissible limit set by the Malaysia Food Safety and Food Regulation 1985, the Food and Agricultural Organization, the World Health Organization, the Ministry of Health Thailand, and the Food and Drug Administration of United States (USFDA). Therefore, continuous monitoring of these bioindicators is essential to minimize the increasing health risk for aquatic life, as well as in food sources for human consumption, in the Kelantan River Basin. HIGHLIGHTS Heavy metals in Marsh Clam (Polymesoda expansa) tissues shows higher concentration in the small and medium sizes compare to big size The concentration of heavy metals (Zn, Cd and Pb) in Marsh Clam (Polymesoda expansa) tissues have exceeded the permissible limit set by Food and Drug Administration of United States (USFDA) and Malaysia Food Safety and Food Regulation Monitoring of heavy metals in aquatic organisms especially near to industrial and sand mining areas should be conducted regularly to reduce the risk to human health GRAPHICAL ABSTRACT

The North Borneo Iranun’s community’s ethnomedicine knowledge on marsh clam (Geloina expansa)

Abstract. Hamdan DDM, Shah JMD, Gumpulan F, Foo J, Lukman KA. 2020. The North Borneo Iranun’s community’s ethnomedicine knowledge on marsh clam (Geloina expansa). Asian J Ethnobiol 21: 30-38. North Borneo is rich with natural resources that have boundless potentials for pharmaceutical product discovery that can lead to socio-economic development in rural areas as suppliers. Even though rich with cultural heritage and comprises of hundred sub-ethnic groups, detail documentation of ethnomedicinal knowledge in North Borneo from different ethnic groups is still limited and could disappear in no time. The ethnomedicinal knowledge of marsh clam (Geloina expansa) use in the Iranun community (respondents no.=28) living in Kampung Rampayan Ulu, Kota Belud in North Borneo were investigated and the concentration of iron, zinc and copper in different parts of marsh clam tissues were determined. In postnatal care of the Iranun community, many believe that marsh clam soup help boost nursing mother milk supply. Marsh clam is rich with micronutrients of iron followed by zinc and copper. The mantle organ has a higher iron concentration than other tissues. The traditional knowledge to heal blood clotting and bruises is topical application of marsh clam mantle organs onto the wound areas. Although participants have ethnomedicinal knowledge on marsh clam, they have poor knowledge of the nutritional benefits of this clam. Lifelong learning of the benefit of marsh clam is necessary from local health care.

The vascular flora of Coastal Indian clam shell middens in South Carolina, U.S.A.

The vascular plant species of Native American clam shell middens were sampled during the 2009–2013 growing seasons. The 15 middens selected in this study include Sewee midden north of Charleston, 6 at Hobcaw Barony in North Inlet-Winyah Bay Natural Research Preserve in North Inlet, and a cluster of 8 middens at Murrells Inlet, South Carolina. The vascular flora consists of 129 species within 114 genera in 48 families. The Poaceae (30 species), Asteraceae (12 species), and Fabaceae (12 species) are the largest families. Sporobolus (5 species) and Cyperus (3 species) are the largest genera in the flora. Species diversity was highest at the Sewee midden, and at the large Allston House midden on private property at Murrells Inlet. All middens in this study border on, or are islands within, salt marshes. Soil salinity and tidal flooding influence the distribution of salt marsh vascular plant species at South Carolina tidal marsh clam shell middens.

Occurrence and Distribution of Marsh Clam, <em>Polymesoda</em> spp. in Marudu Bay, Sabah, Malaysia

Marudu Bay is part of the Tun Mustapha Marine Park, the largest marine protected area within the Malaysian region of the Coral Triangle Initiative. The bay is known for its diversed fisheries resources including bivalves. Although some of these bivalve species are commercially important, their occurrence, distribution and stock status in the bay are not well documented. Hence, the current study was conducted to determine the occurrence, distribution and the stock status of marsh clam, Polymerasoda spp. in the mangrove swamp situated at the southernmost of the Marudu Bay. Samplings were carried out at the mangrove swamps which covered an area of 500 sequare meter per sampling site. Two marsh clams species, Polymesoda erosa and P. expansa were found to inhabit the sampling sites. In general, juvenile marsh clams were noticed to dominate the seaward mangrove swamp, whereas the high tidal regions were dominated by adults. The current study also suggested a link in the distribution and the morphometric measurements of the marsh clams with the sediment grain size.

Heavy metals in marsh clam (Polymesoda expansa) and green mussel (Perna viridis) along the northwest coast of Sabah, Malaysia

Bivalves are known for their ability to accumulate contaminants such as heavy metals. This allows them to be widely used as bioindicator in monitoring of heavy metals in the marine environment. This study was conducted to determine the levels of heavy metals, namely Copper (Cu), Chromium (Cr), Nickel (Ni), Lead (Pb), Arsenic (As), Zinc (Zn) and Manganese (Mn) in marsh clams (Polymesoda expansa) and green mussels (Perna viridis) along the northwest coast of Sabah (Marudu Bay, Ambong Bay, and Mengkabong). The results showed that As (5.1 to 12.8 μg/g) and Mn (33.5 to 116.0 μg/g) concentrations in both marsh clams and green mussels collected from all the sampling stations along the northwest coast of Sabah were much higher than the permissible limit set by the Ministry of Health Malaysia and FAO/ WHO. Similarly, concentration of Zn (265.8 to 535.9 μg/g) in marsh clams from all the sampling areas and that of Cr (53.9 μg/g) in green mussel collected from Marudu Bay were also much higher than the permissible limits. The data also suggested that marsh clams accumulated higher Pb and Zn, whereas green mussels tend to contain higher concentrations of Cr, Cu and Ni. Since bivalves are an important protein source for the local population, a regular monitoring of all edible bivalve species should be conducted so that consumers can be advised about the toxicological and health risks due to consumption of bivalves.

Determination of selected metallic elements in marsh clam, Polymesoda expansa, collected from Tanjung Lumpur Mangrove Forest, Kuantan, Pahang

Presence of metallic elements in organisms is one of the important topics in environmental pollution, toxicology and food safety. It has been extensively studied because of the impact of these elements on the ecosystem and health of the seafood consumers. This study provides information on the concentration of some essential metals (copper, Cu; zinc, Zn) and non-essential metals (cadmium, Cd; lead, Pb) in the commonly consumed marsh clam, Polymesoda expansa, sampled randomly from Tanjung Lumpur mangrove forest, Kuantan, Pahang. It also focuses on the human health risk assessment in terms of toxicity of these metallic elements. Closed acid digestion method was used to digest the samples and Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES) was used to measure the metal contents in the samples. The mean concentration of each metal in the tissues was recorded on a dry weight basis. The average values were: Cu, 15.5 μg/g.; Zn, 296 μg/g ; Pb, 2.31 μg/g and Cd, 1.04 μg/g . These values are within the permissible limits set by Malaysian Food Regulation (1985) and the World Health Organization (1982). The pollution load index (PLI) value of 2.94 indicates that there is no serious metal pollution in this study area. The correlation coefficient matrix between four metallic elements shows positive value, suggesting that the selected metals may have originated from the same source and accumulated in the clam tissue. A positive correlation was noted between the size of the clam and concentrations of Cd, Zn and Cu whereas it was negative for Pb. The present finding shows that the marsh clams from Tanjung Lumpur are safe for human consumption. However, a proper and continuous assessment should be done in order to monitor any changes in the contents of metallic elements since Tanjung Lumpur is near the Kuantan city center and the mining activities at the upstream area might at some stage cause metal pollution.

낙동강 하구 을숙도 갯벌에 서식하는 일본재첩의 분포

낙동강 하구 을숙도 갯벌에 서식하는 일본재첩의 분포

Health Risk Assessment Due to Heavy Metals Exposure via Consumption of Bivalves Harvested from Marudu Bay, Malaysia

Concern over health risk from consumption of bivalves originating from Marudu Bay is escalating due to the rapid agricultural development surrounding the bay. This has motivated us to estimate the health risk index (HRI) of heavy metals from four commercially important and highly exploited bivalve species which are abundant in the bay. Samples (n = 30) of green mussel (Perna viridis), Asiatic hard clam (Meretrix meretrix), Pacific oyster (Crassosstrea gigas) and marsh clam (Polymesoda expans) were acquired from fishermen in Kg. Teritipan, Marudu Bay. These bivalves were analyzed for heavy metals content using the Inductively Couples Plasma-Optical Emission Spectroscopy (ICP-OES). The study found that the mean contents of Arsenic (As) and Manganese (Mn) in all analyzed bivalves exceeded the permissible limits as well as copper (Cu), lead (Pb) and zinc (Zn) in Pacific oyster, and Zn in marsh clam. It was also noticed that consumption of different bivalve species may bring about health risk from different metals as indicated by varied Total Hazard Index (THI) values. Consumption of the four bivalves was noticed to promote high health risk from As intoxication. Although metal pollution index (MPI) analysis revealed that the bivalves from the bay are currently not seriously impacted by heavy metal pollution, vigorous efforts should be taken to preserve the natural condition of the bay for years to come. There are several ways to minimize health issues from bivalve consumption which include keeping the bivalve natural habitat away from heavy metals pollution by strictly enforcing environmental laws and policies, establishing zones for bivalve fisheries, monitoring heavy metals concentration in bivalve on a regular basis and making depuration process a compulsory requirement in every seafood restaurant throughout the country.

Properties of Concrete Containing Ground Waste Cockle and Clam Seashells

Seashells from marine by-product are potentially used in concrete as partial replacement of cement or fine aggregates substitute. The shells generally have high calcium content (CaO) which can improve the concrete physical and mechanical properties. In this research, two types of shells, namely cockle/blood clam (Anadara granosa) and marsh clam (Polymesoda expansa) were burnt and ground as powders to be used as the cement replacement. The shells were ground and replaced the cement at 4% by weight. Specimens were prepared from three different mixtures, i.e. Ordinary Portland Cement (OPC) as a control mix, concrete contains ground marsh clam (OPC Clam) and blood clam concrete (OPC Cockle). Setting time, density, compressive strength, tensile strength of the concrete mixtures were determined for each mixture. Test results indicate that the replacement of cement using different type of shells could yield to different concrete performance. Setting time, density, compressive and tensile strength of the OPC Cockle concrete are considerable lower than the OPC concrete up to 91 days. However, the OPC Clam concrete performed faster setting, higher density, higher compressive and tensile strength than the OPC concrete. Therefore, the CaO content of different type of seashells has the possibility of influencing the physical properties and strength development of concrete.

Clamming Up: An Ethnoarchaeological Study of a Costa Rican Artisanal Clam Fishery

ABSTRACTA vibrant artisanal fishery of the brackish water marsh clam (Polymesoda acuta) is located in the lower Río Tempisque, Costa Rica. Fishermen harvest clams from shoals according to tidal and lunar cycles. They take most clams directly to riverside processing stations to be cooked and sold as salted meat, although some cooked clams are dried, and others sold live. Processing activities result in the formation of shellmounds that share significant similarities and some differences with ancient marsh clam shellmounds of coastal Chiapas, Mexico. In this study, procurement and processing activities are described and quantified, revealing the substantial amount of labor and skill involved in the modern fishery. Implications for archaeological preservation and predictions from optimal foraging theory are evaluated.

Sclerochronological Measures of Seasonality at a Late Woodland Mound on the Mississippi Gulf Coast

Seasonality of site occupation has been an important issue in the archaeology of precolumbian coastal populations in the U.S. Southeast. Sclerochronological oxygen isotope measurements to estimate season of capture were performed on marsh clam (Rangia cuneata) and oyster (Crassostrea virginica) shells from a Late Woodland platform mound in coastal Mississippi. This study is the first oxygen isotope analysis of archaeological Rangia cuneata. The results of the study, supported by vertebrate faunal and plant seasonal indicators and depositional circumstances, indicate that mound trash deposits were generated by short-term activities during the spring and summer months. Factors that could reduce the precision of the seasonal estimates are identified.

Sclerochronological Measures of Seasonality at a Late Woodland Mound on the Mississippi Gulf Coast

Abstract Seasonality of site occupation has been an important issue in the archaeology of precolumbian coastal populations in the U.S. Southeast. Sclerochronological oxygen isotope measurements to estimate season of capture were performed on marsh clam (Rangia cuneata) and oyster (Crassostrea virginica) shells from a Late Woodland platform mound in coastal Mississippi. This study is the first oxygen isotope analysis of archaeological Rangia cuneata. The results of the study, supported by vertebrate faunal and plant seasonal indicators and depositional circumstances, indicate that mound trash deposits were generated by short-term activities during the spring and summer months. Factors that could reduce the precision of the seasonal estimates are identified.

북한강 엷은재첩, Corbicula papyracea (Heude) 의 번식생태

북한강에 서식하고 있는 엷은재첩의 산란생태를 파악하기 위하여, 생식소 발달단계에 따른 생식주기, 군성숙도, 난경의 월별변화를 조사하였다. 각장에 대한 각고, 각폭, 전중, 육중간 의 상대성장식에서 상관계수 (<TEX>$R^2$</TEX>) 는 0.921-0.984로 높은 상관관계를 나타내었다. 엷은재첩은 기수재첩 보다는 소형종이었으며, 동시자웅동체로서 체내에서 수정되어 아가미 보육낭에서 부화되어 체외로 방출하는 난태생종이었다. 월별 비만도는 0.14-0.21 범위로 동계인 12월-2월에 낮은 값을 보이다가 2월부터 서서히 높아지기 시작하여 5월에 0.21로 정점을 보였다. 월별 육중량비는 25.9-38.7%로 비만도의 월별 변화와 같은 경향을 나타내었다. 비만도와 육중량비의 정점이 생식세포의 최성숙기와 1-2개월 차이가 있었다. 생식소의 조직상, 비만도 및 생식세포의 월별 변화를 종합하면 북한강산 엷은재첩 생식년주기는 분열증식기(12-2월), 성장기(2-5월), 성숙기(6-8월), 완숙 및 발생기(8-11월), 회복기(11-12월) 로 구분되어 하계산란종이었다. 군성숙 각장은 12.6 mm 였으며, 16 mm 이상의 개체는 모두 성숙하여 아가미에 보육낭을 형성하였다. Gonadal development and maturation mechanism were studied on the freshwater marsh clam Corbicula papyracea (Heude), which is the endangered species in Korea. The specimens were collected in the rearing ponds and waterway of NFRDI in Gapyeong-gun, Gyeonggi-do from January to December 2004, and then investigated by condition factor, relative growth, gonadal development phases and gonad histological characters based on 30-50 individuals every month. Comparing with the freshwater marsh clam, C. papyracea is small, light olive brown shell and violet interior. The hermaphrodite individuals of C. papyracea take an internal fertilization and fertilized eggs are stored in the foster-sack in the gills, then the hatched juveniles are released outside after an ovoviviparous process. The average water temperature of inhabit area was in range of <TEX>$1.8-27.0^{\circ}C$</TEX> and usually took great effects on the gonad maturation of C. papyracea. The condition factor ranged from 0.14 to 0.21 throughout the year, which was the lowest during winter season (December-February), and gradually increased to the highest value of 0.21 in May. The ratio of meat weight to total weight was 25.9-38.7%, indicating the similar trend with condition factor. The highest values of condition factor and the ratio of meat weight appeared 1-2 months later than gonadosomatic index reached the peak value, it was probably because that the ovoviviparous eggs would spend a long period before hatching from the foster-sack in the gills. To synthesize the characters of meat weight, condition factor and gonad development by histological study, reproductive cycle of C. papyracea could be divided into five successive stages: multiplicative stage (December to February), growing stage (February to May), mature stage (June to August), spawning stage (August to November), recovery stage (November to December). The smallest shell length of matured C. papyracea was 12.6 mm, and individuals, larger than 16 mm, was formed the nursery in the gills.