Comparative Study on Morphological, Biochemical and Distribution Pattern of Villorita Cyprinoides and Meretrix Casta Bivalve Shells in Vembanad Estuary, Kerala, India.

Comparative Study on Morphological, Biochemical and Distribution Pattern of Villorita Cyprinoides and Meretrix Casta Bivalve Shells in Vembanad Estuary, Kerala, India. | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Comparative Study on Morphological, Biochemical and Distribution Pattern of Villorita Cyprinoides and Meretrix Casta Bivalve Shells in Vembanad Estuary, Kerala, India. ANJU MARIA JOSEPH, Dr. M.SURESH GANDHI This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-3984275/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract Estuaries are among the most commercially significant ecosystems on the earth, and they provide different habitats for numerous bivalve species. Clams are one of the most widely distributed and used aquatic bivalves, providing much more protein-rich food than mussels and oysters. Vembanad estuary is one of the richest clam fisheries coastal wetland in Kerala. The current study focused to compare the morphology and biochemistry of Villorita cyprinoides and Meretrix casta shells in Vembanad estuary. It also attempts to understand the variations in clam distribution caused by salinity fluctuations and sediment texture. According to the morphological and morphometric analysis, medium size shells were found in greater abundance in both species. A total of 306 nos of Villorita cyprinoides shells and 169 nos of Meretrix casta shells were obtained from the ten sample locations of Vembanad estuary. The density of Villorita cyprinoides (192 nos) shells is high in the southern part, and Meretrix casta (108 nos) shells are abundant in the northern portion of Vembanad estuary. Villorita cyprinoides has a negative linear correlation with salinity, as indicated by R 2 of 0.96. Meretrix casta , on the other hand, exhibits a positive correlation with salinity, with 0.94 linear coefficient. Villorita cyprinoides is more prevalent in clayey and silty sediments, while Meretrix casta is more common in sandy sediments. According to XRF analysis, calcium is the major oxide, with 39.47% and 38.72% elemental concentration in both species Villorita cyprinoides and Meretrix casta respectively. All other oxides were found only in trace amount. Biochemical Research Methods Bivalves Vembanad estuary Villorita cyprinoides Meretrix casta XRF Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Introduction Estuaries are among the most commercially important environments on the planet, and they provide a variety of habitats for various bivalve species ( Costanza et al., 1997 ). The living forms of bivalves are entirely aquatic, with the highest abundance in both seawater and freshwater (estuarine or backwater). The animals in this class have lived since the Cambrian period and continue to Present day. Bivalves are also known as Pelecypods or Lamellibranchiata, are the second largest class of mollusca. Linnaeus ( 1758 ) was the first to give this group the name "bivalvia". Bivalvia consist of two valves (shells) that are normally identical, equal in size, but mostly inequilateral. Valves are located laterally on either side of the animal and are held together by a strong muscle. Because the right and left valves are identical, the shell displays bilateral symmetry by passing the symmetry plane parallel to the ventral margin of the shell (Senthil2019). Many environmental factors, including latitude (Beukema and Meehan 1985 ), depth and type of bottom (Wieet al., 2020), tidal level (Tran et al., 2020 ), sediment type (Kanaya et al., 2005 ), and burrowing behaviour (Knaust2015), are known to influence shell morphology, size, shape and selective proportions of bivalve species. The hard calcareous shells are the result of a mineralization process that is physiologically and genetically designed by the species. The shells consist diverse types of CaCO 3 such as aragonite, calcite etc. Aragonite is found in prismatic, nacreous, crossed lamellar, complex crossed lamellar, and homogenous structures. Calcite is commonly found in prismatic or foliated structures (Adarsh and Senthil2018). For bivalves, growth increments or rings in shells are used to record the time. Because development rate of animals are mostly determined by environmental factors, alterations in skeleton biochemistry provide a dependable archive of environmental variables encountered by species (Olsson and Kennish 1975 ). Shells are thus exploited as biological archives for paleo-environmental and paleo-climatic conditions. Additionally,the nutritional value of edible molluscs can be estimated using biochemical composition (Celik et al., 2014 ). All the biochemical conditions of shells are influenced by various factors like salinity, sediment composition, temperature, water flow, larval transport and chemical pollutants (Mckeon et al., 2015 ; Galtsoff1947; Korringa and Postma1957). Clams, scallops, mussels, oysters, and shipworms are among the most common bivalve species. Among them clams are one of the most widely distributed and used aquatic molluscs, offering significantly more protein-rich food than mussels and oysters (Arun 2015 ). Clams are economically significant as both a food and an industrial raw material. Barter, tools, decorations, pottery, cement, lime industries, chemicals, fertilizers, and flux material in iron and steel, ferro-alloy, and other metallurgical industries are all made from clam shells. (Ajonina et al.,2005). Aside from these, the shells are employed in biomedical applications such as artificial dental root implantations, orthopedic applications in bone restoration, and so on. Some bivalves are utilized in the treatment of diseases such as anemia, hypertension, labour pain, and constipation. (Ademoluet al., 2015 ). India has abundant clam resources along its coastline, including inshore seas, bays, backwaters, and estuaries (Mohite and Mohite 2012 ). Clams are a commercially important molluscan fishery resource in India, fished for their meat and shell. Clam shells occur extensively along the East Coast of India and in a few places along the West Coast of India. Clam shells occur in a few Indian states such as Kerala, Tamil Nadu, Goa, Maharashtra, Gujarat,Odisha, Group of Andaman and Nicobar Islands(Narasimham1991).Vembanad and Ashtamudi lakes in Kerala arethe richest clam-producing sites in India. Clam and finfish fisheries are the main source of income for coastal communities near the lake (Sathiadhasand Hassan2004). Most of the annual production of Villorita cyprinoides (black clams), about 25,000 t, comes from Vembanad Lake ( Suja and Mohamed 2014). The black clam grows to a length of 30 mm by the end of its first year, and an additional 11 mm during its second year (Laxmilatha 2005). The black clam reaches sexual maturity at a length of 11 to 15 mm.The construction of the Thanneermukkom Bund across the Vembanad lake, has had a significant impact on the reproduction pattern of various clams especially Villorita cyprinoides (Arun2009). The other clams harvested in the lake are the Meretrix casta (grey clam), Paphia malabarica (yellow clam), Etroplus suratensis (Pearlspot) and Sunetta scripta (Kurup1983). Vembanad Lake also includes huge sub-fossil clam shell deposits that are harvested for commercial purposes (Kripa et al., 2004 ).The shells can also be found beneath some of the regions that surround the lake, such as rice paddy farms. This demonstrates that the lands were previously part of the lake but were covered by sediments (Rasalam and Sebastian, 1976 ). Apart from the previous studies, the current study focused on morphological and biochemical comparisons between Villorita cyprinoides and Meretrix casta shells in Vembanad estuary. It also aims to comprehend variations in clam distribution caused by salinity fluctuations and sediment texture. Study area Vembanad is the largest estuarine system and most productive life-supporting coastal wetland in Kerala. Vembanad was designated as the second-largest Ramsar site on India's southwest coast in November 2002 because to its high biodiversity and ecological worth. The area spreads over Kottayam, Alappuzha and Ernakulam districts in Kerala, between Latitude 09°25′30″–10°10′30″N and Longitude 76°21′00″–76°31′30″E. It lies parallel to the coastline with a maximum length of 96.5km and covers an area more than 2033.02 km 2 . The estuary opens into Arabian Sea at Cochin bar mouth andseparated into northern and southern portion by Thanneermukkom Bund- a manmade barrier to prevent the seeping of saline water by the tidal action. The southern portion has fresh water, while the northern section possesses brackish water. The rivers which discharge fresh water into theestuarine system are Periyar and Muvattupuzha on the north and Manimala, Meenachil, Pamba and Achenkovil on the south. Figure.1. Location map of the study area Methodology • Sample collection and pre-treatment The clams were collected from 10 locations along northern and southern part of the Vembanad estuary using van-Veen grab sampler during the month of October 2023. Bivalve shells in sediment samples were sieved onboard, numbered, and washed with water (Aswathy and Parvathi 2018 ). The sediments and shells were then carefully placed in separate clean plastic bags for further investigation. The sampling locations were geographically determined in the field using the Global Positioning System (GPS). • Identification of the bivalve species The major bivalve species found in the Vembanad estuary include Villorita cyprinoides (black clam), Meretrix casta (grey clam), Paphia malabarica (yellow clam), and Sunetta scripta (Ouseph and Jayalakshmi 2023).The collected bivalves were identified based on their exterior and interior shell morphological traits. The observed characteristics were the shell's shape and outline, sculpture, exterior colour, umbo, hinge ligament, internal colour, pallial line, pallial sinus, adductor muscle scars, and dentition.The morphological features of Villorita cyprinoides were studied in detail using the characteristics mentioned by Gray, (1825); Jijina et al., ( 2023 ). Meretrix casta shells were identified in accordance with Gmelin, ( 1791 ); Hamli ( 2015 ). • Measurement of the morphometric parameters The length, height, and width measurements are the morphometric parameters of a bivalve shell (Ambarwatiet al., 2021 ). Digital calliper was used to measure the morphometry of the collected shells. Shell Length - The maximum distance from the anterior to the posterior end of the bivalve shell. It provides insights into the overall size and growth of each specimen. Shell Height- The maximum distance from the dorsal to the ventral side of the bivalve shell. It indicates the vertical dimension and shape of the shell Shell Width - The maximum distance between the valves when they are closed was considered as height. Shell size- After the morphometric analysis, the collected specimens wassorted on the basis of their size such as big, medium and small. The Villorita cyprinoides shell above 3.5 cm is considered a big shell. If the height of the shell ranges between 2.5 and 3.5 cm, it is considered medium size shell, whereas the shell with a height less than 2.5 cm is considered a small shell. The Meretrix Casta shell with 1.5 cm height is considered as medium size and the shells with height higher or lesser than 1.5 cm is considered as big or small shell respectively.The size of all the shells were counted separately and recorded for distribution study. • Sample preparation and analytical studies Following the morphological examination, the shells were immersed in clean water for one night before being cleaned with a hand brush. After that, the valves were immersed in a 2.5% sodium hypochlorite (NaClO) solution for 7 minutes to remove organic contaminants. They were cleaned with deionized water and dried in the sun for a day. (Giordano 2022).The dried shells were crushed and ground into a fine powder using agate mortars. The powdered samples were sieved using a 230-mesh sieve, and 20g powder was extracted for analytical studies. (Senthil 2019 ). XRF (X-ray fluorescence) analytical techniques were used to determine the biochemical properties and elemental composition of collected bivalve shells. • Water salinity and Sediment texture analysis Salinity of water was measured insitu using Hanna instrument- HI98319 Digital Salinity Tester. The salinity measurement unit displayed on parts per thousand (ppt). Each surface sediment sample is completely dried in a hot air oven to eliminate the moisture content. A suitable quantity (weight determined) of each sample is then treated with 0.025 N sodium hexametaphosphate (Calgon) solution in order to facilitate deflocculating. The sample thus disaggregated is washed through a 230 ASTM sieve (mesh opening = 0.063 mm) until clear water passes through, taking care that the washings do not exceed 1000 ml. The portion of the sample retained on the sieve is dried and weighed for obtaining the weight of the sand fraction. The fine fraction (silt and clay) in the washings is analysed by the pipette method in accordance with the procedure adopted by Krumbein and Pettijohn ( 1938 ). Results Morphology Based on taxonomic characterization (Souji 2018 ), 21 landmarks were identified in the bivalve (clam) shells.The identified morphological features of Villorita cyprinoides and Meretrix casta shells were illustrated in Fig. 2. Taxonomic hierarchy of both bivalves were describe in Table 1. Figure 2.The identified morphological features of Villorita cyprinoides and Meretrix casta shells. (1) Left valve, 2) Right valve, 3) Escutcheon, 4) Lunule, 5) Ligament, 6) Umbo, 7) concentric growth lines, 8) Beak, 9) Cardinal Tooth, 10) Lateral Tooth, 11) Socket, 12) Hinge plate, 13) Posterior Adductor Muscle, 14) Anterior Adductor Muscle, 15) Pallial sinus, 16) Pallial line, 17) Commisure, 18) Dorsal margin, 19) Ventral margin, 20) Posterior margin, 21) Anterior margin). Shell description of Villorita cyprinoides shells: Moderately large, thick, ovately triangular, inflating oblique shell, swelled in the umbonal and central regions. Shell is scultured with concentric growth lines and ridges. The valves are inequilateral and have bilateral symmetry. Scars on the adductor muscles and the pallial line are visible. Pallial sinus: thin and rounded at the bottom. When the clams are alive, the shells are black; when they are buried, they turn white. Shell description of Meretrix casta shells: Shell is thick, moderately large, equivalve, and smooth. The umbo is prominently anterior, as are the beaks; the outer shell surface is pale yellowish grey, with a brown sticky periostracum; the inner shell surface is white, with a posterior dark purple ray; the shells are grey when the clams are alive, but turn white after burial. Scars from the adductor muscles and the pallial line are visible. Pallial sinuses are small and rounded at the bottom. Hinges and teeth are strong, and the umbones are inflated. Morphometric Parameters Length, Height and Width of all the collected samples from Vembanad estuary were measured. After taking morphometric data of all collected specimens, their maximum, minimum and mean values were displayed using a bar-diagram (Figure. 3a,b,c). Shell length The maximum length of Villorita cyprinoides and Meretrix casta shells in Vembanad estuary is 41 cm and 25 cm respectively. The minimum length of Villorita cyprinoides is 10 cm and Meretrix casta shell is 8 cm. The mean shell length of collected Villorita cyprinoides is 32 cm and Meretrix casta shell is 20 cm. Figure 3 (a). Variation in Length of Villorita cyprinoides and Meretrix casta shells in Vembanad estuary. Shell height The mean shell height of collected Villorita cyprinoides is 38 cm and Meretrix casta shell is 17 cm. The maximum and minimum height of Villorita cyprinoides are 9 cm and 40 cm respectively. Meretrix casta shells shows 20 cm maximum height and 8 cm minimum height. Figure 3 (b). Variation in Height of Villorita cyprinoides and Meretrix casta shells in Vembanad estuary. Shell width: Villorita cyprinoides shows minimum 10 cm and maximum 38 cm width. The mean width of collected Villorita cyprinoides shell is 29 cm. Meretrix casta shells shows 18 cm maximum width and 10 cm minimum width with the mean width of 16 cm. Figure 3 (c). Variation in Width of Villorita cyprinoides and Meretrix casta shells in Vembanad estuary. Shell size The size distribution of Villorita cyprinoides and Meretrix casta shells in the Vembanad estuary is depicted in Fig. 3(d). In both species medium size shells were found in more numbers. Medium sized 134 Villorita cyprinoides and 71 Meretrix casta shell were collected from the samples. Small size Meretrix casta shells (55) are found more number than large sized shells (43). On the other hand big size Villorita cyprinoides (101) are more abundant than small size shells (71). Figure. 4a and b shows the.size variation of clam shells in Vembanad estuary. Figure 3 (D). Size wise distribution of Villorita cyprinoides and Meretrix casta shells in Vembanad estuary. Figure 4(a).Size variation of Villorita cyprinoides shells Figure 4(b).Size variation of Meretrix casta shells Clam shells distribution. The distribution of bivalves is determined by hydrodynamic variables, sediment types, and depth of substrates (Whetstone 2005). Sediment features influence the number and form of clams, whereas salinity influences the physiological and productive properties of clams (Cao 2022). A total of 306 nos of Villorita cyprinoides shells and 169 nos of Meretrix casta shells were obtained from the ten sample locations of Vembanad estuary. The location no.10 shows the highest record of 73 Villorita cyprinoides shells, and location no.1, records the highest numbers of 29 Meretrix casta shells. Villorita cyprinoides shells were absent in location no.2 and Meretrix casta shells are very less (2) in location no.9. The density of Villorita cyprinoides shells are high in the southern portion (192) and Meretrix casta shells in the northern portion(108) (Fig. 5) . The population of Villorita cyprinoides in northern region is about 18 nos and Meretrix casta in southern region is about 9 nos. 96 Villorita cyprinoides shells and 52 Meretrix casta shells were obtained from the central portion of the estuary. Salinity and clam shell distribution Salinity is a key component that determines the distribution and population of clams(Ouseph and Jayalakshmi 2023). The northern portion of the estuary has higher salinity (22.1–22.2 ppt) than the southern region due to the fresh water flux from main rivers contributes significantly to the low salinity (1.3–2.4 ppt) of the southern section (Fig. 5) . According to the current study, the population of Villorita cyprinoides is higher in the estuary's southern fresh water section than in its brackish region. Meretrix casta , on the other hand, is more prevalent in the northern brackish area. Villorita Cyprinoides exhibits a negative linear relationship with salinity, as measured by R 2 of 0.96. While Meretrix casta has a favorable connection with salinity (0.94 R 2 ) (Figure.6). Figure 5. Salinity and Clam shell distribution Figure 6. Correlation between Salinity and Clam shell distribution in Vembanad estuary Sediment texture and clam shell distribution According to Kripa and Salih (1999), clam density is greatest in clayey, sandy, or muddy estuary substratum. Based on the current study, majority of the clams live in estuary zones with clayey and sandy substratum. The northern half of the estuary is dominated by sand, whereas the southern portion is dominated by clay and silt (Fig. 7 ). Villorita cyprinoides is more common in clayey and silty sediments, but Meretrix casta is more common in sandy sediment. Figure 7. Sand ,silt, clay ratio in Vembanad estuary Biochemistry Oxides XRF was used to evaluate the distribution of oxide in the shells of Villorita cyprinoides and Meretrix casta in the study area. Table 2 shows the XRF measurement findings. The results show that the CaO concentration is higher in both clam species. Villorita cyprinoides accounts for approximately 55.22% of the total, whereas Meretrix casta accounts for approximately 54.18%. All other oxides were found in low concentrations and contribute roughly 2.01 and 2.89 in the shells of Villorita cyprinoides and Meretrix casta , respectively. Figure 8 is a pie diagram describing the primary oxides of shells in the study area. Figure 8. Major oxides in Villorita cyprinoides and Meretrix casta shells in the Vembanad estuary. Loss on ignition (LOI) LOI includes gases, contaminants such as inorganic materials, water and others. These contaminants are frequently found in organic shells. LOI is approximately 42.1% in Villorita cyprinoides and 42.9% in Meretrix casta shell. Elements The elemental content (wt.%) of Villorita cyprinoides and Meretrix casta shells in the Vembanad estuary (Table 2) shows that Ca is particularly abundant in both species when compared to other elements. All other reported elements in shells are merely on a reported level and have no relevance. Villorita cyprinoides has a Ca concentration of 39.47%, while Meretrix casta has a Ca concentration of roughly 38.72%. Conclusion The current study demonstrates that the distribution patterns of Villorita cyprinoides and Meretrix casta in the Vembanad estuary have a strong link with the salinity of the water and the texture of the sediments. Villorita cyprinoides lives in the upper and middle sections of the estuary, where salinity is low, but Meretrix casta lives near the bar mouth, where salinity is high. This indicates, Villorita cyprinoides has a negative linear correlation with salinity, while Meretrix casta has a positive correlation with salinity. Not only salinity, but also sediment texture, influence the distribution and density of clam shells in Vembanad estuary. Villorita cyprinoides is found in clayey and silty sediments, whereas Meretrix casta is found in sandy areas.When compared to the whole clam population, the density of Villorita cyprinoides shells is greater than that of Meretrix casta shells. Furthermore, medium-sized shells were found to be more abundant in both species. According to XRF study, calcium is the most abundant oxide in both and all other oxides were only discovered in trace amounts. The ca elemental concentrations in Villorita cyprinoides and Meretrix casta were 39.47% and 38.72%, respectively. This analysis can be used to evaluate the changes in quantity and quality of clam shells in the Vembanad estuary accordance with the salinity and textural changes of sediments. Declarations Acknowledgement The authors are sincerely thank our Head of Department, Department of Geology, University of Madras for providing lab facilities to carry out this work. 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Present status of clam fisheries of India. Jour. of the Mar. Biol. Ass. of India, 33(1&2), 76-88. Rasalam, E. J. & Sebastian. (1976). Thelimeshell fisheries of the Vembanad lake, Kerala. J. Mar Biol. Ass. India, 18(2), 323-355. Sathiadhas, R., & Hassan, F. (2004). Empowerment of women involved in clam fisheries of Kerala-a case study. Ind. Jour. of Soc. Research, 46(1), 39-48. Senthil Kumar, G.R. (2019). Biochemical, biomineral and microstructural properties of the present day bivalves from the Thoothukudi coast, Tamil Nadu, India. Int. Res. J. Earth Sci., 7(3), 1-9. Souji S. (2018) Molluscan fauna of southeast coast of India with special references to Bivalvia.PhD thesis. University of Kerala, 168. Suja, N & Mohamed, K S. (2012).The black clam, Villorita cyprinoides , fishery in the State of Kerala, India. Marine Fisheries Review, 72 (3), 48-61. Tran, D., Perrigault, M., Ciret, P., & Payton, L. (2020). Bivalve mollusc circadian clock genes can run at tidal frequency. Proceedings of the Royal Society B, 287(1918), 2440. Wei, C. L., Chen, M., Wicksten, M. K., & Rowe, G. T. (2020).Macrofauna bivalve diversity from the deep northern Gulf of Mexico. Ecological Research, 35 (2), 343-361. Whetstone, J. M., Sturmer, L. N., & Oesterling, M. J. (2005).Biology and culture of the hard clam. Southern Regional Aquaculture Center, 433, 1-6. Tables Table 1: Taxonomic hierarchy of Villorita Cyprinoides and Meretrix Casta . Kingdom Animalia Phylum Mollusca Class Bivalvia Subclass Autobranchia Infraclass Heteroconchia Subterclass Euheterodonta Superorder Imparidentia Order Venerida Superfamily Cyrenoidea Veneroidea Family Cyrenidae Veneridae Genus Villorita Meretrix Species Villorita cyprinoides Meretrix casta (Mollusca Base (2024): World Register of Marine Species) Table 2:Major oxides and element concentrations in Villorita cyprinoides and Meretrix casta shells of the study area. Oxides Formula Villorita cyprinoides (m/m% ) Meretrix casta (m/m% ) Element Villorita cyprinoides (Weight %) Meretrix casta (Weight %) Calcium oxide CaO 55.22 54.18 Ca 39.47 38.72 Aluminium oxide Al2O 3 0.21 0.07 Al 0.11 0.04 Iron oxide Fe2O 3 0.23 0.14 Fe 0.16 0.10 Silicon oxide SiO 2 0.43 0.21 Si 0.20 0.10 Magnesium oxide MgO 0.39 1.21 Mg 0.24 0.73 Sodium oxide Na 2 O 0.42 0.24 Na 0.31 0.18 Potassium oxide K 2 O 0.12 0.001 K 0.10 0.00 Strontium oxide SrO 0.21 1.02 Sr 0.18 0.86 Loss on ignition LOI 42.1 42.9 Additional Declarations The authors declare no competing interests. Cite Share Download PDF Status: Posted Version 1 posted You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-3984275","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":274631215,"identity":"32149da1-0943-49ac-850a-ceed8b278963","order_by":0,"name":"ANJU MARIA JOSEPH","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA50lEQVRIiWNgGAWjYHCCBBDBw8DDxvgAxOAjRQuzAYjBRrxlPGxsEiCaoBb+2Q3PpG7U3JPh7zmWVvk1x06GjYH54aMbeLRI3DmQJp1zrJhH4mzbsduy25KBDmMzNs7BZ82NBKAWtgQehvPsbbcltzEDtfCwSePTIg/W8i+BRx6opVhyWz1hLQYgLbltCTwGQIcxftx2mLAWwxsJyda5fQk8hmeOJUszbjsODGsCfpG7kZN4O+dbgr3cmTTDjz+3Vdvzszc/fIzX+ww8CXAmMw+YxKscBNgPwJmMPwiqHgWjYBSMgpEIAPtIQ76/70veAAAAAElFTkSuQmCC","orcid":"","institution":"University of Madras","correspondingAuthor":true,"submittingAuthor":false,"prefix":"","firstName":"ANJU","middleName":"MARIA","lastName":"JOSEPH","suffix":""},{"id":274631216,"identity":"bcaf836d-c9ef-4c70-aba9-15428fb121b2","order_by":1,"name":"Dr. M.SURESH GANDHI","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA8UlEQVRIiWNgGAWjYPCCAyDCjCGhAkgxMzeQouUMSAsjKVoY20A0AS26/WfMPnz4c8euf3bztgcP59VG87cDtfyo2IZTi9mNHOOZM9ueJc+4c6zcIHHb8dwZhxkbGHvO3MajhceYmbfhcDLDjRwzicRtx3IbgFqYGdvwaDl/xpj5z5/DyfJgLXOO5c4nqOVAjjEzA9thOwOwloaa3A0EtdxIK2bsbTucYHgjrUwi4diB3I1ALQfx+uX84c0MP/4ctpe7kbxN8kdNXe6884cPPvhRgVsLDCQ2QOjDYPIAQfVAYA+l64hRPApGwSgYBSMMAACmNGPUzO6MMgAAAABJRU5ErkJggg==","orcid":"https://orcid.org/0000-0002-0428-9804","institution":"University of Madras","correspondingAuthor":true,"submittingAuthor":false,"prefix":"Dr.","firstName":"M.SURESH","middleName":"","lastName":"GANDHI","suffix":""}],"badges":[],"createdAt":"2024-02-24 07:41:14","currentVersionCode":1,"declarations":{"humanSubjects":false,"vertebrateSubjects":true,"conflictsOfInterestStatement":false,"humanSubjectEthicalGuidelines":false,"humanSubjectConsent":false,"humanSubjectClinicalTrial":false,"humanSubjectCaseReport":false,"vertebrateSubjectEthicalGuidelines":true,"coiExplicitlySet":false},"doi":"10.21203/rs.3.rs-3984275/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-3984275/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":51686716,"identity":"fc9b2118-23fc-4e15-95c3-8deb06b12f7c","added_by":"auto","created_at":"2024-02-27 08:41:34","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":97917,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eLocation map of the study area\u003c/strong\u003e\u003c/p\u003e","description":"","filename":"Fig.1.Locationmapofthestudyarea.png","url":"https://assets-eu.researchsquare.com/files/rs-3984275/v1/b87df63da23d15d7f7823699.png"},{"id":51686718,"identity":"38c68514-529e-4051-8ba0-1dd705cecc69","added_by":"auto","created_at":"2024-02-27 08:41:34","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":199258,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eThe identified morphological features of \u003c/strong\u003e\u003cem\u003e\u003cstrong\u003eVillorita cyprinoides \u003c/strong\u003e\u003c/em\u003e\u003cstrong\u003eand \u003c/strong\u003e\u003cem\u003e\u003cstrong\u003eMeretrix casta\u003c/strong\u003e\u003c/em\u003e\u003cstrong\u003eshells.\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cem\u003e(1) Left valve, 2) Right valve, 3) Escutcheon, 4) Lunule, 5) Ligament, 6) Umbo, 7) concentric growth lines, 8) Beak, 9) Cardinal Tooth, 10) Lateral Tooth, 11) Socket, 12) Hinge plate, 13) Posterior Adductor Muscle, 14) Anterior Adductor Muscle, 15) Pallial sinus, 16) Pallial line, 17) Commisure, 18) Dorsal margin, 19) Ventral margin, 20) Posterior margin, 21) Anterior margin).\u003c/em\u003e\u003c/p\u003e","description":"","filename":"Fig.2.TheidentifiedmorphologicalfeaturesofVilloritacyprinoidesandMeretrixcastashells..png","url":"https://assets-eu.researchsquare.com/files/rs-3984275/v1/7f82b6b2144c35afd45d28f9.png"},{"id":51686717,"identity":"e1984e57-4bc2-431e-8f20-40f8e98abc8d","added_by":"auto","created_at":"2024-02-27 08:41:34","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":132416,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003e(a). Variation in Length of \u003c/strong\u003e\u003cem\u003e\u003cstrong\u003eVillorita cyprinoides\u003c/strong\u003e\u003c/em\u003e\u003cstrong\u003e and \u003c/strong\u003e\u003cem\u003e\u003cstrong\u003eMeretrix casta \u003c/strong\u003e\u003c/em\u003e\u003cstrong\u003eshells in Vembanad estuary.\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e(b). Variation in Height of \u003c/strong\u003e\u003cem\u003e\u003cstrong\u003eVillorita cyprinoides\u003c/strong\u003e\u003c/em\u003e\u003cstrong\u003e and \u003c/strong\u003e\u003cem\u003e\u003cstrong\u003eMeretrix casta\u003c/strong\u003e\u003c/em\u003e\u003cstrong\u003e shells in Vembanad estuary.\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e(c). Variation in Width of \u003c/strong\u003e\u003cem\u003e\u003cstrong\u003eVillorita cyprinoides\u003c/strong\u003e\u003c/em\u003e\u003cstrong\u003e and \u003c/strong\u003e\u003cem\u003e\u003cstrong\u003eMeretrix casta\u003c/strong\u003e\u003c/em\u003e\u003cstrong\u003e shells in Vembanad estuary.\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e(D). Size wise distribution of \u003c/strong\u003e\u003cem\u003e\u003cstrong\u003eVillorita cyprinoides\u003c/strong\u003e\u003c/em\u003e\u003cstrong\u003e and \u003c/strong\u003e\u003cem\u003e\u003cstrong\u003eMeretrix casta \u003c/strong\u003e\u003c/em\u003e\u003cstrong\u003eshells in Vembanad estuary.\u003c/strong\u003e\u003c/p\u003e","description":"","filename":"3.png","url":"https://assets-eu.researchsquare.com/files/rs-3984275/v1/5c94377d1068dbb88559c73b.png"},{"id":51686723,"identity":"bcd45678-863c-4d33-8baa-f01f6ebb60e0","added_by":"auto","created_at":"2024-02-27 08:41:34","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":1623369,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003e(a).Size variation of Villorita cyprinoides shells\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e(b).Size variation of Meretrix casta shells\u003c/strong\u003e\u003c/p\u003e","description":"","filename":"4.png","url":"https://assets-eu.researchsquare.com/files/rs-3984275/v1/2caeea4dd0063cab753dc0aa.png"},{"id":51686721,"identity":"f5b234ce-d3e3-4984-b29f-3f959fa3ea8e","added_by":"auto","created_at":"2024-02-27 08:41:34","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":343697,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eSalinity and Clam shell distribution\u003c/strong\u003e\u003c/p\u003e","description":"","filename":"Fig.5.SalinityandClamshelldistribution.png","url":"https://assets-eu.researchsquare.com/files/rs-3984275/v1/e50249b4702fcb6ca4e2ea76.png"},{"id":51686722,"identity":"d25d26b1-35d2-47a4-9235-159548c70504","added_by":"auto","created_at":"2024-02-27 08:41:34","extension":"png","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":70327,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eCorrelation between Salinity and Clam shell distribution in Vembanad estuary\u003c/strong\u003e\u003c/p\u003e","description":"","filename":"Fig.6.CorrelationbetweenSalinityandClamshelldistributioninVembanadestuary..png","url":"https://assets-eu.researchsquare.com/files/rs-3984275/v1/83059d6195ceda7370e5d331.png"},{"id":51686900,"identity":"bd5ba489-bf6f-4e68-b68e-8911f93a5c5b","added_by":"auto","created_at":"2024-02-27 08:49:34","extension":"png","order_by":7,"title":"Figure 7","display":"","copyAsset":false,"role":"figure","size":106738,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eSand ,silt, clay ratio in Vembanad estuary\u003c/strong\u003e\u003c/p\u003e","description":"","filename":"Fig.7.Sandsiltclayratio.png","url":"https://assets-eu.researchsquare.com/files/rs-3984275/v1/2ece33cc2c713af083d049ba.png"},{"id":51686719,"identity":"56cb9ba9-d90f-4692-8b1d-0829c9476897","added_by":"auto","created_at":"2024-02-27 08:41:34","extension":"png","order_by":8,"title":"Figure 8","display":"","copyAsset":false,"role":"figure","size":71391,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eMajor oxides in \u003c/strong\u003e\u003cem\u003e\u003cstrong\u003eVillorita cyprinoides\u003c/strong\u003e\u003c/em\u003e\u003cstrong\u003e and \u003c/strong\u003e\u003cem\u003e\u003cstrong\u003eMeretrix casta\u003c/strong\u003e\u003c/em\u003e\u003cstrong\u003eshells in the Vembanad estuary.\u003c/strong\u003e\u003c/p\u003e","description":"","filename":"Fig.8.MajoroxidesinVilloritacyprinoidesandMeretrixcastashellsintheVembanadestuary..png","url":"https://assets-eu.researchsquare.com/files/rs-3984275/v1/dc16427e238552c84050f8de.png"},{"id":51688161,"identity":"0e2e8b78-ba0a-4ea0-9b1d-f7c02d899ae3","added_by":"auto","created_at":"2024-02-27 08:57:40","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":3426686,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-3984275/v1/57d4556a-6fea-405f-abfb-bc5aa5d1ea33.pdf"}],"financialInterests":"The authors declare no competing interests.","formattedTitle":"\u003cp\u003e\u003cstrong\u003eComparative Study on Morphological, Biochemical and Distribution Pattern of Villorita Cyprinoides and Meretrix Casta Bivalve Shells in Vembanad Estuary, Kerala, India.\u003c/strong\u003e\u003c/p\u003e","fulltext":[{"header":"Introduction","content":"\u003cp\u003eEstuaries are among the most commercially important environments on the planet, and they provide a variety of habitats for various bivalve species \u003cb\u003e(\u003c/b\u003eCostanza et al., \u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e1997\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eThe living forms of bivalves are entirely aquatic, with the highest abundance in both seawater and freshwater (estuarine or backwater). The animals in this class have lived since the Cambrian period and continue to Present day. Bivalves are also known as Pelecypods or Lamellibranchiata, are the second largest class of mollusca. Linnaeus (\u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e1758\u003c/span\u003e) was the first to give this group the name \"bivalvia\". Bivalvia consist of two valves (shells) that are normally identical, equal in size, but mostly inequilateral. Valves are located laterally on either side of the animal and are held together by a strong muscle. Because the right and left valves are identical, the shell displays bilateral symmetry by passing the symmetry plane parallel to the ventral margin of the shell (Senthil2019). Many environmental factors, including latitude (Beukema and Meehan \u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e1985\u003c/span\u003e), depth and type of bottom (Wieet al., 2020), tidal level (Tran et al., \u003cspan citationid=\"CR38\" class=\"CitationRef\"\u003e2020\u003c/span\u003e), sediment type (Kanaya et al., \u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e2005\u003c/span\u003e), and burrowing behaviour (Knaust2015), are known to influence shell morphology, size, shape and selective proportions of bivalve species. The hard calcareous shells are the result of a mineralization process that is physiologically and genetically designed by the species. The shells consist diverse types of CaCO\u003csub\u003e3\u003c/sub\u003e such as aragonite, calcite etc. Aragonite is found in prismatic, nacreous, crossed lamellar, complex crossed lamellar, and homogenous structures. Calcite is commonly found in prismatic or foliated structures (Adarsh and Senthil2018). For bivalves, growth increments or rings in shells are used to record the time. Because development rate of animals are mostly determined by environmental factors, alterations in skeleton biochemistry provide a dependable archive of environmental variables encountered by species (Olsson and Kennish \u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e1975\u003c/span\u003e). Shells are thus exploited as biological archives for paleo-environmental and paleo-climatic conditions. Additionally,the nutritional value of edible molluscs can be estimated using biochemical composition (Celik et al., \u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e2014\u003c/span\u003e). All the biochemical conditions of shells are influenced by various factors like salinity, sediment composition, temperature, water flow, larval transport and chemical pollutants (Mckeon et al., \u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e2015\u003c/span\u003e; Galtsoff1947; Korringa and Postma1957).\u003c/p\u003e \u003cp\u003eClams, scallops, mussels, oysters, and shipworms are among the most common bivalve species. Among them clams are one of the most widely distributed and used aquatic molluscs, offering significantly more protein-rich food than mussels and oysters (Arun \u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e2015\u003c/span\u003e\u003cb\u003e).\u003c/b\u003e Clams are economically significant as both a food and an industrial raw material. Barter, tools, decorations, pottery, cement, lime industries, chemicals, fertilizers, and flux material in iron and steel, ferro-alloy, and other metallurgical industries are all made from clam shells. (Ajonina et al.,2005). Aside from these, the shells are employed in biomedical applications such as artificial dental root implantations, orthopedic applications in bone restoration, and so on. Some bivalves are utilized in the treatment of diseases such as anemia, hypertension, labour pain, and constipation. (Ademoluet al., \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2015\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eIndia has abundant clam resources along its coastline, including inshore seas, bays, backwaters, and estuaries (Mohite and Mohite \u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e2012\u003c/span\u003e). Clams are a commercially important molluscan fishery resource in India, fished for their meat and shell. Clam shells occur extensively along the East Coast of India and in a few places along the West Coast of India. Clam shells occur in a few Indian states such as Kerala, Tamil Nadu, Goa, Maharashtra, Gujarat,Odisha, Group of Andaman and Nicobar Islands(Narasimham1991).Vembanad and Ashtamudi lakes in Kerala arethe richest clam-producing sites in India. Clam and finfish fisheries are the main source of income for coastal communities near the lake (Sathiadhasand Hassan2004). Most of the annual production of \u003cem\u003eVillorita cyprinoides\u003c/em\u003e (black clams), about 25,000 t, comes from Vembanad Lake \u003cb\u003e(\u003c/b\u003eSuja and Mohamed 2014). The black clam grows to a length of 30 mm by the end of its first year, and an additional 11 mm during its second year (Laxmilatha 2005). The black clam reaches sexual maturity at a length of 11 to 15 mm.The construction of the Thanneermukkom Bund across the Vembanad lake, has had a significant impact on the reproduction pattern of various clams especially \u003cem\u003eVillorita cyprinoides\u003c/em\u003e (Arun2009). The other clams harvested in the lake are the \u003cem\u003eMeretrix casta\u003c/em\u003e (grey clam), \u003cem\u003ePaphia malabarica\u003c/em\u003e (yellow clam), \u003cem\u003eEtroplus suratensis\u003c/em\u003e (Pearlspot) and \u003cem\u003eSunetta scripta\u003c/em\u003e (Kurup1983). Vembanad Lake also includes huge sub-fossil clam shell deposits that are harvested for commercial purposes (Kripa et al., \u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e2004\u003c/span\u003e).The shells can also be found beneath some of the regions that surround the lake, such as rice paddy farms. This demonstrates that the lands were previously part of the lake but were covered by sediments (Rasalam and Sebastian, \u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e1976\u003c/span\u003e). Apart from the previous studies, the current study focused on morphological and biochemical comparisons between \u003cem\u003eVillorita cyprinoides\u003c/em\u003e and \u003cem\u003eMeretrix casta\u003c/em\u003e shells in Vembanad estuary. It also aims to comprehend variations in clam distribution caused by salinity fluctuations and sediment texture.\u003c/p\u003e\n\u003ch3\u003eStudy area\u003c/h3\u003e\n\u003cp\u003eVembanad is the largest estuarine system and most productive life-supporting coastal wetland in Kerala. Vembanad was designated as the second-largest Ramsar site on India's southwest coast in November 2002 because to its high biodiversity and ecological worth. The area spreads over Kottayam, Alappuzha and Ernakulam districts in Kerala, between Latitude 09\u0026deg;25\u0026prime;30\u0026Prime;\u0026ndash;10\u0026deg;10\u0026prime;30\u0026Prime;N and Longitude 76\u0026deg;21\u0026prime;00\u0026Prime;\u0026ndash;76\u0026deg;31\u0026prime;30\u0026Prime;E. It lies parallel to the coastline with a maximum length of 96.5km and covers an area more than 2033.02 km\u003csup\u003e2\u003c/sup\u003e. The estuary opens into Arabian Sea at Cochin bar mouth andseparated into northern and southern portion by Thanneermukkom Bund- a manmade barrier to prevent the seeping of saline water by the tidal action. The southern portion has fresh water, while the northern section possesses brackish water. The rivers which discharge fresh water into theestuarine system are Periyar and Muvattupuzha on the north and Manimala, Meenachil, Pamba and Achenkovil on the south.\u003c/p\u003e \u003cp\u003e \u003cb\u003eFigure.1. Location map of the study area\u003c/b\u003e \u003c/p\u003e"},{"header":"Methodology","content":"\u003cdiv id=\"Sec4\" class=\"Section2\"\u003e \u003ch2\u003e\u0026bull; Sample collection and pre-treatment\u003c/h2\u003e \u003cp\u003eThe clams were collected from 10 locations along northern and southern part of the Vembanad estuary using van-Veen grab sampler during the month of October 2023. Bivalve shells in sediment samples were sieved onboard, numbered, and washed with water (Aswathy and Parvathi \u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e2018\u003c/span\u003e). The sediments and shells were then carefully placed in separate clean plastic bags for further investigation. The sampling locations were geographically determined in the field using the Global Positioning System (GPS).\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec5\" class=\"Section2\"\u003e \u003ch2\u003e\u0026bull; Identification of the bivalve species\u003c/h2\u003e \u003cp\u003eThe major bivalve species found in the Vembanad estuary include \u003cem\u003eVillorita cyprinoides\u003c/em\u003e (black clam), \u003cem\u003eMeretrix casta\u003c/em\u003e (grey clam), \u003cem\u003ePaphia malabarica\u003c/em\u003e (yellow clam), and \u003cem\u003eSunetta scripta\u003c/em\u003e (Ouseph and Jayalakshmi 2023).The collected bivalves were identified based on their exterior and interior shell morphological traits. The observed characteristics were the shell's shape and outline, sculpture, exterior colour, umbo, hinge ligament, internal colour, pallial line, pallial sinus, adductor muscle scars, and dentition.The morphological features of \u003cem\u003eVillorita cyprinoides\u003c/em\u003e were studied in detail using the characteristics mentioned by Gray, (1825); Jijina et al., (\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e2023\u003c/span\u003e). \u003cem\u003eMeretrix casta\u003c/em\u003e shells were identified in accordance with Gmelin, (\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e1791\u003c/span\u003e); Hamli (\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e2015\u003c/span\u003e).\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec6\" class=\"Section2\"\u003e \u003ch2\u003e\u0026bull; Measurement of the morphometric parameters\u003c/h2\u003e \u003cp\u003eThe length, height, and width measurements are the morphometric parameters of a bivalve shell (Ambarwatiet al., \u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e2021\u003c/span\u003e). Digital calliper was used to measure the morphometry of the collected shells.\u003c/p\u003e \u003cp\u003e \u003cb\u003eShell Length\u003c/b\u003e- The maximum distance from the anterior to the posterior end of the bivalve shell. It provides insights into the overall size and growth of each specimen.\u003c/p\u003e \u003cp\u003e \u003cb\u003eShell Height-\u003c/b\u003e The maximum distance from the dorsal to the ventral side of the bivalve shell. It indicates the vertical dimension and shape of the shell\u003c/p\u003e \u003cp\u003e \u003cb\u003eShell Width\u003c/b\u003e- The maximum distance between the valves when they are closed was considered as height.\u003c/p\u003e \u003cp\u003e \u003cb\u003eShell size-\u003c/b\u003e After the morphometric analysis, the collected specimens wassorted on the basis of their size such as big, medium and small. The \u003cem\u003eVillorita cyprinoides\u003c/em\u003e shell above 3.5 cm is considered a big shell. If the height of the shell ranges between 2.5 and 3.5 cm, it is considered medium size shell, whereas the shell with a height less than 2.5 cm is considered a small shell. The \u003cem\u003eMeretrix Casta\u003c/em\u003e shell with 1.5 cm height is considered as medium size and the shells with height higher or lesser than 1.5 cm is considered as big or small shell respectively.The size of all the shells were counted separately and recorded for distribution study.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec7\" class=\"Section2\"\u003e \u003ch2\u003e\u0026bull; Sample preparation and analytical studies\u003c/h2\u003e \u003cp\u003eFollowing the morphological examination, the shells were immersed in clean water for one night before being cleaned with a hand brush. After that, the valves were immersed in a 2.5% sodium hypochlorite (NaClO) solution for 7 minutes to remove organic contaminants. They were cleaned with deionized water and dried in the sun for a day. (Giordano 2022).The dried shells were crushed and ground into a fine powder using agate mortars. The powdered samples were sieved using a 230-mesh sieve, and 20g powder was extracted for analytical studies. (Senthil 2019\u003cem\u003e).\u003c/em\u003e XRF (X-ray fluorescence) analytical techniques were used to determine the biochemical properties and elemental composition of collected bivalve shells.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec8\" class=\"Section2\"\u003e \u003ch2\u003e\u0026bull; Water salinity and Sediment texture analysis\u003c/h2\u003e \u003cp\u003eSalinity of water was measured insitu using Hanna instrument- HI98319 Digital Salinity Tester. The salinity measurement unit displayed on parts per thousand (ppt).\u003c/p\u003e \u003cp\u003eEach surface sediment sample is completely dried in a hot air oven to eliminate the moisture content. A suitable quantity (weight determined) of each sample is then treated with 0.025 N sodium hexametaphosphate (Calgon) solution in order to facilitate deflocculating. The sample thus disaggregated is washed through a 230 ASTM sieve (mesh opening\u0026thinsp;=\u0026thinsp;0.063 mm) until clear water passes through, taking care that the washings do not exceed 1000 ml. The portion of the sample retained on the sieve is dried and weighed for obtaining the weight of the sand fraction. The fine fraction (silt and clay) in the washings is analysed by the pipette method in accordance with the procedure adopted by Krumbein and Pettijohn (\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e1938\u003c/span\u003e).\u003c/p\u003e \u003c/div\u003e"},{"header":"Results","content":"\u003cp\u003e \u003cul\u003e \u003cli\u003e \u003cp\u003eMorphology\u003c/p\u003e \u003c/li\u003e \u003c/ul\u003e \u003c/p\u003e \u003cp\u003eBased on taxonomic characterization (Souji \u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e2018\u003c/span\u003e), 21 landmarks were identified in the bivalve (clam) shells.The identified morphological features of \u003cem\u003eVillorita cyprinoides\u003c/em\u003e and \u003cem\u003eMeretrix casta\u003c/em\u003e shells were illustrated in \u003cb\u003eFig.\u0026nbsp;2.\u003c/b\u003e Taxonomic hierarchy of both bivalves were describe in \u003cb\u003eTable\u0026nbsp;1.\u003c/b\u003e\u003c/p\u003e \u003cp\u003e \u003cb\u003eFigure\u0026nbsp;2.The identified morphological features of\u003c/b\u003e \u003cb\u003eVillorita cyprinoides\u003c/b\u003e \u003cb\u003eand\u003c/b\u003e \u003cb\u003eMeretrix casta\u003c/b\u003e \u003cb\u003eshells.\u003c/b\u003e\u003c/p\u003e \u003cp\u003e \u003cem\u003e(1) Left valve, 2) Right valve, 3) Escutcheon, 4) Lunule, 5) Ligament, 6) Umbo, 7) concentric growth lines, 8) Beak, 9) Cardinal Tooth, 10) Lateral Tooth, 11) Socket, 12) Hinge plate, 13) Posterior Adductor Muscle, 14) Anterior Adductor Muscle, 15) Pallial sinus, 16) Pallial line, 17) Commisure, 18) Dorsal margin, 19) Ventral margin, 20) Posterior margin, 21) Anterior margin).\u003c/em\u003e \u003c/p\u003e \u003cp\u003e \u003cem\u003eShell description of Villorita cyprinoides\u003c/em\u003e shells: Moderately large, thick, ovately triangular, inflating oblique shell, swelled in the umbonal and central regions. Shell is scultured with concentric growth lines and ridges. The valves are inequilateral and have bilateral symmetry. Scars on the adductor muscles and the pallial line are visible. Pallial sinus: thin and rounded at the bottom. When the clams are alive, the shells are black; when they are buried, they turn white.\u003c/p\u003e \u003cp\u003e \u003cem\u003eShell description of Meretrix casta\u003c/em\u003e shells: Shell is thick, moderately large, equivalve, and smooth. The umbo is prominently anterior, as are the beaks; the outer shell surface is pale yellowish grey, with a brown sticky periostracum; the inner shell surface is white, with a posterior dark purple ray; the shells are grey when the clams are alive, but turn white after burial. Scars from the adductor muscles and the pallial line are visible. Pallial sinuses are small and rounded at the bottom. Hinges and teeth are strong, and the umbones are inflated.\u003c/p\u003e \u003cp\u003e \u003cul\u003e \u003cli\u003e \u003cp\u003eMorphometric Parameters\u003c/p\u003e \u003c/li\u003e \u003c/ul\u003e \u003c/p\u003e \u003cp\u003eLength, Height and Width of all the collected samples from Vembanad estuary were measured. After taking morphometric data of all collected specimens, their maximum, minimum and mean values were displayed using a bar-diagram \u003cb\u003e(Figure. 3a,b,c).\u003c/b\u003e\u003c/p\u003e \u003cp\u003e \u003cstrong\u003eShell length\u003c/strong\u003e \u003cp\u003eThe maximum length of \u003cem\u003eVillorita cyprinoides\u003c/em\u003e and \u003cem\u003eMeretrix casta\u003c/em\u003e shells in Vembanad estuary is 41 cm and 25 cm respectively. The minimum length of \u003cem\u003eVillorita cyprinoides\u003c/em\u003e is 10 cm and Meretrix casta shell is 8 cm. The mean shell length of collected \u003cem\u003eVillorita cyprinoides\u003c/em\u003e is 32 cm and \u003cem\u003eMeretrix casta\u003c/em\u003e shell is 20 cm.\u003c/p\u003e \u003c/p\u003e \u003cp\u003e \u003cb\u003eFigure\u0026nbsp;3 (a). Variation in Length of\u003c/b\u003e \u003cb\u003eVillorita cyprinoides\u003c/b\u003e \u003cb\u003eand\u003c/b\u003e \u003cb\u003eMeretrix casta\u003c/b\u003e \u003cb\u003eshells in Vembanad estuary.\u003c/b\u003e\u003c/p\u003e \u003cp\u003e \u003cstrong\u003eShell height\u003c/strong\u003e \u003cp\u003eThe mean shell height of collected \u003cem\u003eVillorita cyprinoides\u003c/em\u003e is 38 cm and \u003cem\u003eMeretrix casta\u003c/em\u003e shell is 17 cm. The maximum and minimum height of \u003cem\u003eVillorita cyprinoides\u003c/em\u003e are 9 cm and 40 cm respectively. \u003cem\u003eMeretrix casta\u003c/em\u003e shells shows 20 cm maximum height and 8 cm minimum height.\u003c/p\u003e \u003c/p\u003e \u003cp\u003e \u003cb\u003eFigure\u0026nbsp;3 (b). Variation in Height of\u003c/b\u003e \u003cb\u003eVillorita cyprinoides\u003c/b\u003e \u003cb\u003eand\u003c/b\u003e \u003cb\u003eMeretrix casta\u003c/b\u003e \u003cb\u003eshells in Vembanad estuary.\u003c/b\u003e\u003c/p\u003e \u003cp\u003e \u003cem\u003eShell width: Villorita cyprinoides\u003c/em\u003e shows minimum 10 cm and maximum 38 cm width. The mean width of collected \u003cem\u003eVillorita cyprinoides\u003c/em\u003e shell is 29 cm. \u003cem\u003eMeretrix casta\u003c/em\u003e shells shows 18 cm maximum width and 10 cm minimum width with the mean width of 16 cm.\u003c/p\u003e \u003cp\u003e \u003cb\u003eFigure\u0026nbsp;3 (c). Variation in Width of\u003c/b\u003e \u003cb\u003eVillorita cyprinoides\u003c/b\u003e \u003cb\u003eand\u003c/b\u003e \u003cb\u003eMeretrix casta\u003c/b\u003e \u003cb\u003eshells in Vembanad estuary.\u003c/b\u003e\u003c/p\u003e \u003cp\u003e \u003cstrong\u003eShell size\u003c/strong\u003e \u003cp\u003eThe size distribution of \u003cem\u003eVillorita cyprinoides\u003c/em\u003e and \u003cem\u003eMeretrix casta\u003c/em\u003e shells in the Vembanad estuary is depicted in Fig.\u0026nbsp;3(d). In both species medium size shells were found in more numbers. Medium sized 134 \u003cem\u003eVillorita cyprinoides\u003c/em\u003e and 71 Meretrix casta shell were collected from the samples. Small size \u003cem\u003eMeretrix casta\u003c/em\u003e shells (55) are found more number than large sized shells (43). On the other hand big size \u003cem\u003eVillorita cyprinoides\u003c/em\u003e (101) are more abundant than small size shells (71).\u003cb\u003eFigure. 4a and b\u003c/b\u003e shows the.size variation of clam shells in Vembanad estuary.\u003c/p\u003e \u003c/p\u003e \u003cp\u003e \u003cb\u003eFigure\u0026nbsp;3 (D). Size wise distribution of\u003c/b\u003e \u003cb\u003eVillorita cyprinoides\u003c/b\u003e \u003cb\u003eand\u003c/b\u003e \u003cb\u003eMeretrix casta\u003c/b\u003e \u003cb\u003eshells in Vembanad estuary.\u003c/b\u003e\u003c/p\u003e \u003cp\u003e \u003cb\u003eFigure\u0026nbsp;4(a).Size variation of Villorita cyprinoides shells\u003c/b\u003e \u003c/p\u003e \u003cp\u003e \u003cb\u003eFigure\u0026nbsp;4(b).Size variation of Meretrix casta shells\u003c/b\u003e \u003c/p\u003e \u003cp\u003e \u003cul\u003e \u003cli\u003e \u003cp\u003eClam shells distribution.\u003c/p\u003e \u003c/li\u003e \u003c/ul\u003e \u003c/p\u003e \u003cp\u003eThe distribution of bivalves is determined by hydrodynamic variables, sediment types, and depth of substrates (Whetstone 2005). Sediment features influence the number and form of clams, whereas salinity influences the physiological and productive properties of clams (Cao 2022). A total of 306 nos of \u003cem\u003eVillorita cyprinoides\u003c/em\u003e shells and 169 nos of \u003cem\u003eMeretrix casta\u003c/em\u003e shells were obtained from the ten sample locations of Vembanad estuary. The location no.10 shows the highest record of 73 \u003cem\u003eVillorita cyprinoides\u003c/em\u003e shells, and location no.1, records the highest numbers of 29 \u003cem\u003eMeretrix casta\u003c/em\u003e shells. \u003cem\u003eVillorita cyprinoides\u003c/em\u003e shells were absent in location no.2 and \u003cem\u003eMeretrix casta\u003c/em\u003e shells are very less (2) in location no.9. The density of \u003cem\u003eVillorita cyprinoides\u003c/em\u003e shells are high in the southern portion (192) and \u003cem\u003eMeretrix casta\u003c/em\u003e shells in the northern portion(108) \u003cb\u003e(Fig.\u0026nbsp;5)\u003c/b\u003e. The population of \u003cem\u003eVillorita cyprinoides\u003c/em\u003e in northern region is about 18 nos and \u003cem\u003eMeretrix casta\u003c/em\u003e in southern region is about 9 nos. 96 \u003cem\u003eVillorita cyprinoides\u003c/em\u003e shells and 52 \u003cem\u003eMeretrix casta\u003c/em\u003e shells were obtained from the central portion of the estuary.\u003c/p\u003e \u003cp\u003e \u003cul\u003e \u003cli\u003e \u003cp\u003eSalinity and clam shell distribution\u003c/p\u003e \u003c/li\u003e \u003c/ul\u003e \u003c/p\u003e \u003cp\u003eSalinity is a key component that determines the distribution and population of clams(Ouseph and Jayalakshmi 2023). The northern portion of the estuary has higher salinity (22.1\u0026ndash;22.2 ppt) than the southern region due to the fresh water flux from main rivers contributes significantly to the low salinity (1.3\u0026ndash;2.4 ppt) of the southern section \u003cb\u003e(Fig.\u0026nbsp;5)\u003c/b\u003e. According to the current study, the population of \u003cem\u003eVillorita cyprinoides\u003c/em\u003e is higher in the estuary's southern fresh water section than in its brackish region. \u003cem\u003eMeretrix casta\u003c/em\u003e, on the other hand, is more prevalent in the northern brackish area. Villorita Cyprinoides exhibits a negative linear relationship with salinity, as measured by R\u003csup\u003e2\u003c/sup\u003e of 0.96. While \u003cem\u003eMeretrix casta\u003c/em\u003e has a favorable connection with salinity (0.94 R\u003csup\u003e2\u003c/sup\u003e) \u003cb\u003e(Figure.6).\u003c/b\u003e\u003c/p\u003e \u003cp\u003e \u003cb\u003eFigure\u0026nbsp;5. Salinity and Clam shell distribution\u003c/b\u003e \u003c/p\u003e \u003cp\u003e \u003cb\u003eFigure\u0026nbsp;6. Correlation between Salinity and Clam shell distribution in Vembanad estuary\u003c/b\u003e \u003c/p\u003e \u003cp\u003e \u003cul\u003e \u003cli\u003e \u003cp\u003eSediment texture and clam shell distribution\u003c/p\u003e \u003c/li\u003e \u003c/ul\u003e \u003c/p\u003e \u003cp\u003eAccording to Kripa and Salih (1999), clam density is greatest in clayey, sandy, or muddy estuary substratum. Based on the current study, majority of the clams live in estuary zones with clayey and sandy substratum. The northern half of the estuary is dominated by sand, whereas the southern portion is dominated by clay and silt (Fig.\u0026nbsp;7\u003cb\u003e).\u003c/b\u003e \u003cem\u003eVillorita cyprinoides\u003c/em\u003e is more common in clayey and silty sediments, but \u003cem\u003eMeretrix casta\u003c/em\u003e is more common in sandy sediment.\u003c/p\u003e \u003cp\u003e \u003cb\u003eFigure\u0026nbsp;7. Sand ,silt, clay ratio in Vembanad estuary\u003c/b\u003e \u003c/p\u003e \u003cp\u003e \u003cul\u003e \u003cli\u003e \u003cp\u003eBiochemistry\u003c/p\u003e \u003c/li\u003e \u003c/ul\u003e \u003c/p\u003e \u003cp\u003e \u003cstrong\u003eOxides\u003c/strong\u003e \u003cp\u003eXRF was used to evaluate the distribution of oxide in the shells of \u003cem\u003eVillorita cyprinoides\u003c/em\u003e and \u003cem\u003eMeretrix casta\u003c/em\u003e in the study area. Table\u0026nbsp;2 shows the XRF measurement findings. The results show that the CaO concentration is higher in both clam species. \u003cem\u003eVillorita cyprinoides\u003c/em\u003e accounts for approximately 55.22% of the total, whereas \u003cem\u003eMeretrix casta\u003c/em\u003e accounts for approximately 54.18%. All other oxides were found in low concentrations and contribute roughly 2.01 and 2.89 in the shells of \u003cem\u003eVillorita cyprinoides\u003c/em\u003e and \u003cem\u003eMeretrix casta\u003c/em\u003e, respectively. Figure\u0026nbsp;8 is a pie diagram describing the primary oxides of shells in the study area.\u003c/p\u003e \u003c/p\u003e \u003cp\u003e \u003cb\u003eFigure\u0026nbsp;8. Major oxides in\u003c/b\u003e \u003cb\u003eVillorita cyprinoides\u003c/b\u003e \u003cb\u003eand\u003c/b\u003e \u003cb\u003eMeretrix casta\u003c/b\u003e \u003cb\u003eshells in the Vembanad estuary.\u003c/b\u003e\u003c/p\u003e \u003cp\u003e \u003cstrong\u003eLoss on ignition (LOI)\u003c/strong\u003e \u003cp\u003eLOI includes gases, contaminants such as inorganic materials, water and others. These contaminants are frequently found in organic shells. LOI is approximately 42.1% in \u003cem\u003eVillorita cyprinoides\u003c/em\u003e and 42.9% in \u003cem\u003eMeretrix casta\u003c/em\u003e shell.\u003c/p\u003e \u003c/p\u003e \u003cp\u003e \u003cstrong\u003eElements\u003c/strong\u003e \u003cp\u003eThe elemental content (wt.%) of Villorita cyprinoides and Meretrix casta shells in the Vembanad estuary (Table\u0026nbsp;2) shows that Ca is particularly abundant in both species when compared to other elements. All other reported elements in shells are merely on a reported level and have no relevance. \u003cem\u003eVillorita cyprinoides\u003c/em\u003e has a Ca concentration of 39.47%, while \u003cem\u003eMeretrix casta\u003c/em\u003e has a Ca concentration of roughly 38.72%.\u003c/p\u003e \u003c/p\u003e"},{"header":"Conclusion","content":"\u003cp\u003eThe current study demonstrates that the distribution patterns of \u003cem\u003eVillorita cyprinoides\u003c/em\u003e and \u003cem\u003eMeretrix casta\u003c/em\u003e in the Vembanad estuary have a strong link with the salinity of the water and the texture of the sediments. \u003cem\u003eVillorita cyprinoides\u003c/em\u003e lives in the upper and middle sections of the estuary, where salinity is low, but \u003cem\u003eMeretrix casta\u003c/em\u003e lives near the bar mouth, where salinity is high. This indicates,\u003cem\u003eVillorita cyprinoides\u003c/em\u003e has a negative linear correlation with salinity, while \u003cem\u003eMeretrix casta\u003c/em\u003e has a positive correlation with salinity. Not only salinity, but also sediment texture, influence the distribution and density of clam shells in Vembanad estuary. \u003cem\u003eVillorita cyprinoides\u003c/em\u003e is found in clayey and silty sediments, whereas \u003cem\u003eMeretrix casta\u003c/em\u003e is found in sandy areas.When compared to the whole clam population, the density of \u003cem\u003eVillorita cyprinoides\u003c/em\u003e shells is greater than that of \u003cem\u003eMeretrix casta\u003c/em\u003e shells. Furthermore, medium-sized shells were found to be more abundant in both species. According to XRF study, calcium is the most abundant oxide in both and all other oxides were only discovered in trace amounts. The ca elemental concentrations in \u003cem\u003eVillorita cyprinoides\u003c/em\u003e and \u003cem\u003eMeretrix casta\u003c/em\u003e were 39.47% and 38.72%, respectively. This analysis can be used to evaluate the changes in quantity and quality of clam shells in the Vembanad estuary accordance with the salinity and textural changes of sediments.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eAcknowledgement\u003c/strong\u003e\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eThe authors are sincerely thank our Head of Department, Department of Geology, University of Madras for providing lab facilities to carry out this work. The authors also thankful to the anonymous referees for correct the manuscript.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConflict of Interest\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThere will be no conflict of Interest for the authors. \u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthor’s contribution\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFirst author AMJ\u0026nbsp;\u003c/strong\u003e- \u0026nbsp;sample collection, Sediment and geochemical analysis, manuscript drafting;\u003cstrong\u003e\u0026nbsp;Second author MSG-\u0026nbsp;\u003c/strong\u003especies identification, Interpretation and data analysis\u003cstrong\u003e.\u003c/strong\u003e\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n \u003cli\u003eAdarsh, A. S., \u0026amp; Senthil Kumar, G. R. (2018).Chemical, mineralogical and microstructural properties of Villorita cyprinoides (bivalvia) shells of Vembanad lake, Kerala, India. 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(1791).Systema Naturae per Regna Tria Naturae, Secundum Classes, Ordines, Genera, Species, cum Characteribus, Differentiis, Synonymis, locis 1(6): 3021-3909.\u003c/li\u003e\n \u003cli\u003eGray, J.E. (1825). A synopsis of the genera of cirripedes arranged in natural families, with a description of some new species. \u003cem\u003eAnnals of Philosophy.\u003c/em\u003e 10: 97-107.\u003c/li\u003e\n \u003cli\u003eHamli, H. (2015). Habitat, morphology, population genetics and reproductive biology of hard clam (bivalvia: Veneridae) from two locations in Sarawak. Doctoral thesis, University Putra Malaysia.\u0026nbsp;85.\u003c/li\u003e\n \u003cli\u003eJijina, K., Anand, P. P., Neethu, C. B., \u0026amp; ShibuVardhanan, Y. (2023).Species. 24(73), 1001.\u003c/li\u003e\n \u003cli\u003eKanaya, G., Nobata, E., Toya, T., \u0026amp; Kikuchi, E. (2005).Effects of different feeding habits of three bivalve species on sediment characteristics and benthic diatom abundance. Marine Ecology Progress Series, 299, 67-78.\u0026nbsp;\u003c/li\u003e\n \u003cli\u003eKennish, M. J., \u0026amp; Olsson, R. K. (1975).Effects of thermal discharges on the microstructural growth of Mercenariamercenaria. Environmental Geology, 1, 41-64.\u003c/li\u003e\n \u003cli\u003eKnaust, D. (2015). Siphonichnidae (new ichnofamily) attributed to the burrowing activity of bivalves: Ichnotaxonomy, behaviour and palaeoenvironmental implications. Earth-Science Reviews, 150, 497-519.\u003c/li\u003e\n \u003cli\u003eKorringa, P., \u0026amp; Postma, H. (1957).Investigations into the fertility of the Gulf of Naples and adjacent salt water lakes, with special reference to shellfish cultivation. Pubbl.staz. zool. Napoli, 29, 229-284.\u003c/li\u003e\n \u003cli\u003eKripa, V., \u0026amp; Mohammed Salih, K. Y. (1999). Growth and reproduction of the rock oyster Saccostreacucullata (Born) in Ashtamudi lake Kerala.\u0026nbsp;The Fourth Indian Fisheries Forum, 24(28), 371-372.\u003c/li\u003e\n \u003cli\u003eKripa, V., Velayudhan, T. S., Joseph, S., Alloycious, P. S., Joseph, M., Radhakrishnan, P., \u0026amp; Jenni, B. (2004). Clam fisheries of Vembanad Lake, Kerala with observations on the socio economic conditions of the clam fisheries. Marine Fisheries Information Service, Technical and Extension Series, 179, 14-16.\u003c/li\u003e\n \u003cli\u003eKrumbein and Pettijohn.(1938). Manual of Sedimentary Petrography, Appliton Century Crofts Inc, New York, 166.\u003c/li\u003e\n \u003cli\u003eKurup, B. M. and Samuel, C. T. (1983). Systematic and distribution of fishes of the family Leiognathidae (Pisces) of the Vembanad lake, Kerala, S. India. Rec. Zool. Surv. India, 80, 387-411.\u003c/li\u003e\n \u003cli\u003eLaxmilatha, P., Velayudhan, T. S., Kripa, V., Jenni, B., \u0026amp; Alloycious, P. S. (2005). Biology of the black clam, \u003cem\u003eVillorita cyprinoides\u003c/em\u003e (Gray) in the backwaters of Vembanad Lake. Indian Journal of Fisheries, 52(3), 361-366.\u003c/li\u003e\n \u003cli\u003eLinnaeus C. (1758). Systemanatur\u0026aelig; per regna trianatur\u0026aelig;, secundum classes, ordines, genera, species, cum characteribus, differentiis, synonymis, locis. Tomus I. Editiodecima, reformata, 1(4), 824.\u003c/li\u003e\n \u003cli\u003eMcKeon CS, Tunberg BG, Johnston CA, \u0026nbsp;\u0026amp; Barshis DJ. (2015). Ecological drivers and habitat associations of estuarine bivalves.PeerJ, 3,\u0026nbsp;1348.\u003c/li\u003e\n \u003cli\u003eMohite, S.A. \u0026amp; Mohite, A.S.(2012). Resource analysis of Venerid clams along the south-west coast of Maharashtra. Asian J. Animal Sci, 7(1), 27-35.\u0026nbsp;\u003c/li\u003e\n \u003cli\u003eMollusca Base eds. (2024). Mollusca Base. Accessed at https://www.molluscabase.org on 2024-01-14.\u003c/li\u003e\n \u003cli\u003eNarasimham K.A. (1991). Present status of clam fisheries of India. Jour. of the Mar. Biol. Ass. of India, 33(1\u0026amp;2), 76-88.\u003c/li\u003e\n \u003cli\u003eRasalam, E. J. \u0026amp; Sebastian. (1976). Thelimeshell fisheries of the Vembanad lake, Kerala. J. Mar Biol. Ass. India, 18(2), 323-355.\u003c/li\u003e\n \u003cli\u003eSathiadhas, R., \u0026amp; Hassan, F. (2004). Empowerment of women involved in clam fisheries of Kerala-a case study. Ind. Jour. of Soc. Research, 46(1), 39-48.\u003c/li\u003e\n \u003cli\u003eSenthil Kumar, G.R. (2019). Biochemical, biomineral and microstructural properties of the present day bivalves from the Thoothukudi coast, Tamil Nadu, India. Int. Res. J. Earth Sci., 7(3), 1-9.\u003c/li\u003e\n \u003cli\u003eSouji S. (2018) Molluscan fauna of southeast coast of India with special references to Bivalvia.PhD thesis. University of Kerala, 168.\u003c/li\u003e\n \u003cli\u003eSuja, N \u0026amp; Mohamed, K S. (2012).The black clam, \u003cem\u003eVillorita cyprinoides\u003c/em\u003e, fishery in the State of Kerala, India. Marine Fisheries Review, 72 (3), 48-61.\u0026nbsp;\u003c/li\u003e\n \u003cli\u003eTran, D., Perrigault, M., Ciret, P., \u0026amp; Payton, L. (2020). Bivalve mollusc circadian clock genes can run at tidal frequency. Proceedings of the Royal Society B, 287(1918), 2440.\u003c/li\u003e\n \u003cli\u003eWei, C. L., Chen, M., Wicksten, M. K., \u0026amp; Rowe, G. T. (2020).Macrofauna bivalve diversity from the deep northern Gulf of Mexico. Ecological Research, \u003cem\u003e35\u003c/em\u003e(2), 343-361.\u003c/li\u003e\n \u003cli\u003eWhetstone, J. M., Sturmer, L. N., \u0026amp; Oesterling, M. J. (2005).Biology and culture of the hard clam. Southern Regional Aquaculture Center, 433, 1-6.\u003c/li\u003e\n\u003c/ol\u003e"},{"header":"Tables","content":"\u003cp\u003e\u003cstrong\u003eTable 1: Taxonomic hierarchy of \u003cem\u003eVillorita Cyprinoides\u003c/em\u003e and \u003cem\u003eMeretrix Casta\u003c/em\u003e.\u003c/strong\u003e\u003c/p\u003e\n\u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\" width=\"352\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd width=\"25.28409090909091%\" valign=\"bottom\"\u003e\n \u003cp\u003e\u0026nbsp;Kingdom\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"74.7159090909091%\" colspan=\"2\" valign=\"bottom\"\u003e\n \u003cp\u003eAnimalia\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"25.28409090909091%\" valign=\"bottom\"\u003e\n \u003cp\u003e\u0026nbsp;Phylum\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"74.7159090909091%\" colspan=\"2\" valign=\"bottom\"\u003e\n \u003cp\u003eMollusca\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"25.28409090909091%\" valign=\"bottom\"\u003e\n \u003cp\u003eClass\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"74.7159090909091%\" colspan=\"2\" valign=\"bottom\"\u003e\n \u003cp\u003eBivalvia\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"25.28409090909091%\" valign=\"bottom\"\u003e\n \u003cp\u003eSubclass\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"74.7159090909091%\" colspan=\"2\" valign=\"bottom\"\u003e\n \u003cp\u003eAutobranchia\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"25.28409090909091%\" valign=\"bottom\"\u003e\n \u003cp\u003eInfraclass\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"74.7159090909091%\" colspan=\"2\" valign=\"bottom\"\u003e\n \u003cp\u003eHeteroconchia\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"25.28409090909091%\" valign=\"bottom\"\u003e\n \u003cp\u003eSubterclass\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"74.7159090909091%\" colspan=\"2\" valign=\"bottom\"\u003e\n \u003cp\u003eEuheterodonta\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"25.28409090909091%\" valign=\"bottom\"\u003e\n \u003cp\u003eSuperorder\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"74.7159090909091%\" colspan=\"2\" valign=\"bottom\"\u003e\n \u003cp\u003eImparidentia\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"25.28409090909091%\" valign=\"bottom\"\u003e\n \u003cp\u003eOrder\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"74.7159090909091%\" colspan=\"2\" valign=\"bottom\"\u003e\n \u003cp\u003eVenerida\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"25.356125356125357%\" valign=\"bottom\"\u003e\n \u003cp\u003eSuperfamily\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"43.58974358974359%\" valign=\"bottom\"\u003e\n \u003cp\u003eCyrenoidea\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"31.054131054131055%\" valign=\"bottom\"\u003e\n \u003cp\u003eVeneroidea\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"25.356125356125357%\" valign=\"bottom\"\u003e\n \u003cp\u003eFamily\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"43.58974358974359%\" valign=\"bottom\"\u003e\n \u003cp\u003eCyrenidae\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"31.054131054131055%\" valign=\"bottom\"\u003e\n \u003cp\u003eVeneridae\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"25.356125356125357%\" valign=\"bottom\"\u003e\n \u003cp\u003eGenus\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"43.58974358974359%\" valign=\"bottom\"\u003e\n \u003cp\u003eVillorita\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"31.054131054131055%\" valign=\"bottom\"\u003e\n \u003cp\u003eMeretrix\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"25.356125356125357%\" valign=\"bottom\"\u003e\n \u003cp\u003eSpecies\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"43.58974358974359%\" valign=\"bottom\"\u003e\n \u003cp\u003e\u003cem\u003eVillorita cyprinoides\u0026nbsp;\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"31.054131054131055%\" valign=\"bottom\"\u003e\n \u003cp\u003e\u003cem\u003eMeretrix casta\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003e(Mollusca Base (2024): World Register of Marine Species)\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eTable 2:Major oxides and element concentrations in \u003cem\u003eVillorita cyprinoides\u003c/em\u003e and \u003cem\u003eMeretrix casta\u0026nbsp;\u003c/em\u003eshells of the study area.\u003c/strong\u003e\u003c/p\u003e\n\u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\" width=\"767\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd width=\"14.732724902216427%\"\u003e\n \u003cp\u003e\u003cstrong\u003eOxides\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"9.908735332464145%\"\u003e\n \u003cp\u003e\u003cstrong\u003e\u0026nbsp;Formula\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"18.513689700130378%\"\u003e\n \u003cp\u003e\u003cstrong\u003e\u003cem\u003eVillorita cyprinoides\u003c/em\u003e\u003c/strong\u003e\u003cstrong\u003e\u0026nbsp; (m/m% )\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"15.123859191655802%\"\u003e\n \u003cp\u003e\u003cstrong\u003e\u003cem\u003eMeretrix casta\u003c/em\u003e\u003c/strong\u003e\u003cstrong\u003e\u0026nbsp;(m/m% )\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"9.517601043024772%\"\u003e\n \u003cp\u003e\u003cstrong\u003eElement\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"18.513689700130378%\"\u003e\n \u003cp\u003e\u003cstrong\u003e\u003cem\u003eVillorita cyprinoides\u003c/em\u003e\u003c/strong\u003e\u003cstrong\u003e\u0026nbsp;(Weight %)\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"13.689700130378096%\"\u003e\n \u003cp\u003e\u003cstrong\u003e\u003cem\u003eMeretrix casta\u003c/em\u003e\u003c/strong\u003e\u003cstrong\u003e\u0026nbsp;(Weight %)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"14.732724902216427%\"\u003e\n \u003cp\u003eCalcium oxide\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"9.908735332464145%\"\u003e\n \u003cp\u003eCaO\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"18.513689700130378%\"\u003e\n \u003cp\u003e55.22\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"15.123859191655802%\"\u003e\n \u003cp\u003e54.18\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"9.517601043024772%\"\u003e\n \u003cp\u003eCa\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"18.513689700130378%\"\u003e\n \u003cp\u003e39.47\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"13.689700130378096%\"\u003e\n \u003cp\u003e38.72\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"14.732724902216427%\"\u003e\n \u003cp\u003eAluminium oxide\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"9.908735332464145%\"\u003e\n \u003cp\u003eAl2O\u003csub\u003e3\u003c/sub\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"18.513689700130378%\"\u003e\n \u003cp\u003e0.21\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"15.123859191655802%\"\u003e\n \u003cp\u003e0.07\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"9.517601043024772%\"\u003e\n \u003cp\u003eAl\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"18.513689700130378%\"\u003e\n \u003cp\u003e0.11\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"13.689700130378096%\"\u003e\n \u003cp\u003e0.04\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"14.732724902216427%\"\u003e\n \u003cp\u003eIron oxide\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"9.908735332464145%\"\u003e\n \u003cp\u003eFe2O\u003csub\u003e3\u003c/sub\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"18.513689700130378%\"\u003e\n \u003cp\u003e0.23\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"15.123859191655802%\"\u003e\n \u003cp\u003e0.14\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"9.517601043024772%\"\u003e\n \u003cp\u003eFe\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"18.513689700130378%\"\u003e\n \u003cp\u003e0.16\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"13.689700130378096%\"\u003e\n \u003cp\u003e0.10\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"14.732724902216427%\"\u003e\n \u003cp\u003eSilicon oxide\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"9.908735332464145%\"\u003e\n \u003cp\u003eSiO\u003csub\u003e2\u003c/sub\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"18.513689700130378%\"\u003e\n \u003cp\u003e0.43\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"15.123859191655802%\"\u003e\n \u003cp\u003e0.21\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"9.517601043024772%\"\u003e\n \u003cp\u003eSi\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"18.513689700130378%\"\u003e\n \u003cp\u003e0.20\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"13.689700130378096%\"\u003e\n \u003cp\u003e0.10\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"14.732724902216427%\"\u003e\n \u003cp\u003eMagnesium oxide\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"9.908735332464145%\"\u003e\n \u003cp\u003eMgO\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"18.513689700130378%\"\u003e\n \u003cp\u003e0.39\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"15.123859191655802%\"\u003e\n \u003cp\u003e1.21\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"9.517601043024772%\"\u003e\n \u003cp\u003eMg\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"18.513689700130378%\"\u003e\n \u003cp\u003e0.24\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"13.689700130378096%\"\u003e\n \u003cp\u003e0.73\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"14.732724902216427%\"\u003e\n \u003cp\u003eSodium oxide\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"9.908735332464145%\"\u003e\n \u003cp\u003eNa\u003csub\u003e2\u003c/sub\u003eO\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"18.513689700130378%\"\u003e\n \u003cp\u003e0.42\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"15.123859191655802%\"\u003e\n \u003cp\u003e0.24\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"9.517601043024772%\"\u003e\n \u003cp\u003eNa\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"18.513689700130378%\"\u003e\n \u003cp\u003e0.31\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"13.689700130378096%\"\u003e\n \u003cp\u003e0.18\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"14.732724902216427%\"\u003e\n \u003cp\u003ePotassium oxide\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"9.908735332464145%\"\u003e\n \u003cp\u003eK\u003csub\u003e2\u003c/sub\u003eO\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"18.513689700130378%\"\u003e\n \u003cp\u003e0.12\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"15.123859191655802%\"\u003e\n \u003cp\u003e0.001\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"9.517601043024772%\"\u003e\n \u003cp\u003eK\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"18.513689700130378%\"\u003e\n \u003cp\u003e0.10\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"13.689700130378096%\"\u003e\n \u003cp\u003e0.00\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"14.732724902216427%\"\u003e\n \u003cp\u003eStrontium oxide\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"9.908735332464145%\"\u003e\n \u003cp\u003eSrO\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"18.513689700130378%\"\u003e\n \u003cp\u003e0.21\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"15.123859191655802%\"\u003e\n \u003cp\u003e1.02\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"9.517601043024772%\"\u003e\n \u003cp\u003eSr\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"18.513689700130378%\"\u003e\n \u003cp\u003e0.18\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"13.689700130378096%\"\u003e\n \u003cp\u003e0.86\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"14.732724902216427%\"\u003e\n \u003cp\u003eLoss on ignition\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"9.908735332464145%\"\u003e\n \u003cp\u003eLOI\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"18.513689700130378%\"\u003e\n \u003cp\u003e42.1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"15.123859191655802%\"\u003e\n \u003cp\u003e42.9\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"9.517601043024772%\"\u003e\u003cbr\u003e\u003c/td\u003e\n \u003ctd width=\"18.513689700130378%\"\u003e\u003cbr\u003e\u003c/td\u003e\n \u003ctd width=\"13.689700130378096%\"\u003e\u003cbr\u003e\u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":true,"hideJournal":true,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"Bivalves, Vembanad estuary,Villorita cyprinoides, Meretrix casta, XRF","lastPublishedDoi":"10.21203/rs.3.rs-3984275/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-3984275/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eEstuaries are among the most commercially significant ecosystems on the earth, and they provide different habitats for numerous bivalve species. Clams are one of the most widely distributed and used aquatic bivalves, providing much more protein-rich food than mussels and oysters. Vembanad estuary is one of the richest clam fisheries coastal wetland in Kerala. The current study focused to compare the morphology and biochemistry of \u003cem\u003eVillorita cyprinoides\u003c/em\u003e and \u003cem\u003eMeretrix casta\u003c/em\u003e shells in Vembanad estuary. It also attempts to understand the variations in clam distribution caused by salinity fluctuations and sediment texture. According to the morphological and morphometric analysis, medium size shells were found in greater abundance in both species. A total of 306 nos of \u003cem\u003eVillorita cyprinoides\u003c/em\u003e shells and 169 nos of\u0026nbsp; \u003cem\u003eMeretrix casta\u003c/em\u003e shells were obtained from the ten sample locations of Vembanad estuary. The density of \u003cem\u003eVillorita cyprinoides\u003c/em\u003e (192 nos) shells is\u0026nbsp;high in the southern part, and \u003cem\u003eMeretrix casta\u003c/em\u003e (108 nos) shells are abundant in the northern portion of Vembanad estuary. \u003cem\u003eVillorita cyprinoides\u003c/em\u003e has a negative linear correlation with salinity, as indicated by R\u003csup\u003e2\u003c/sup\u003e of 0.96. \u003cem\u003eMeretrix casta\u003c/em\u003e, on the other hand, exhibits a positive correlation with salinity, with 0.94 linear coefficient. \u003cem\u003eVillorita cyprinoides\u003c/em\u003e is more prevalent in clayey and silty sediments, while \u003cem\u003eMeretrix casta\u003c/em\u003e is more common in sandy sediments. According to XRF analysis, calcium is the major oxide, with 39.47% and 38.72% elemental concentration in both species \u003cem\u003eVillorita cyprinoides\u003c/em\u003e and \u003cem\u003eMeretrix casta\u003c/em\u003e respectively. All other oxides were found only in trace amount.\u003c/p\u003e","manuscriptTitle":"Comparative Study on Morphological, Biochemical and Distribution Pattern of Villorita Cyprinoides and Meretrix Casta Bivalve Shells in Vembanad Estuary, Kerala, India.","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2024-02-27 08:41:30","doi":"10.21203/rs.3.rs-3984275/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"8bdfb2d9-1072-408f-b037-89522874427c","owner":[],"postedDate":"February 27th, 2024","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[{"id":28993807,"name":"Biochemical Research Methods"}],"tags":[],"updatedAt":"2024-02-27T08:41:30+00:00","versionOfRecord":[],"versionCreatedAt":"2024-02-27 08:41:30","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-3984275","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-3984275","identity":"rs-3984275","version":["v1"]},"buildId":"7rjqhiLT3MXkJMwkYKINL","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}