Corbicula Fluminea Research Articles

Succession of macrozoobenthic communities and its drivers in Meiliang Bay of Lake Taihu during the past 40 years

梅梁湾是太湖北部最大湖湾,也是太湖生态环境问题最严重的区域之一,近年来对太湖治理力度不断加大,然而对其生态状况演变的认识尚不清晰。本文基于长期监测及文献资料,获得1980s以来太湖梅梁湾底栖动物及环境因子数据,分析底栖动物种类组成、优势种、丰度的时空变化,应用非度量多维尺度分析(NMDS)和随机森林(RF)分析群落结构演变及其与环境因子的关系。结果表明,梅梁湾1980-2019年共记录到44属(种)底栖动物,以摇蚊幼虫和软体动物为主,总丰度年际变化显著,40年来底栖群落结构发生显著变化,优势种经历了由较敏感的软体类为主到以耐污寡毛类、摇蚊幼虫等为主的转变。综合NMDS和随机森林分析结果,梅梁湾底栖动物群落演变大致可分为4个阶段:1980s及以前,物种多样性丰富,以河蚬(Corbicula fluminea)等大型软体动物为优势种;1990s-2007年,底栖动物群落快速退化,以耐污种占优;2008-2016年,水生态略有恢复,河蚬等清洁种略有回升;2017-2019年,耐污种优势度和丰度反弹。近40年来梅梁湾底栖动物群落变化主要受底质氮磷、有机质和水体营养盐、蓝藻水华等环境因子变化的影响,此外水生植物演替也是影响底栖动物群落变化的重要因素。;Meiliang Bay is the largest bay in the northern Lake Taihu which has the most serious ecological and environmental problems. In recent years, while the governance of Lake Taihu has been strengthened, the understanding of the succession of its ecological status remains unclear. Based on the long-term monitoring data and historical literature, this study analyzed the temporal and spatial variation of macrozoobenthos composition, the dominant species and density in Meiliang Bay since 1980s. Community succession and its relationship with environmental factors are examined by non-metric multidimensional scale analysis (NMDS) and random forest (RF). The results showed that 44 taxa were recorded in Meiliang Bay from 1980 to 2019, mainly composed of chironomid larvae and molluscs, with substantial interannual changes in total density. The benthic community structure has changed significantly in the past 40 years, with the dominant species have changed from sensitive species dominated by molluscs to pollution tolerant species characterized by oligochaetes and chironomids. Based on the results of NMDS and random forest analyses, the benthic community succession in Meiliang Bay can be roughly divided into four stages. Stage 1 (before 1980s) had Corbicula fluminea and other large molluscs dominated the community characterized by high species diversity. In stage 2 (1990s-2007), the benthic community degenerated rapidly, dominated by pollution-tolerant species. From 2008 to 2016 (stage 3), the ecological condition showed a recovery trend, with the sensitive species increased slightly. Stage 4 from 2017 to 2019, the dominance and density of pollution tolerant species rebounded. The changes of benthic communities in Meiliang Bay in recent 40 years are mainly regulated by sediment nitrogen and phosphorus, organic matter and water column nutrients, followed by aquatic macrophytes degradation.

Seasonal Dynamics in Gross Biochemical Composition of Asiatic Hard Clam, Meretrix meretrix Collected from the West Coast of Cox's Bazar, Bangladesh

The study aimed to evaluate the seasonal dynamics ingross biochemical compositions of Asiatic hard clam (Meretrix meretrix) collectedmonthly from the west coast ofCox's Bazar, Bangladesh fromJuly2018 to June 2019. The proportion of crude protein, crude lipids, carbohydrates, ash, crude fiber and moisture contents of the clam varied from 10.81 to 15.56%, 0.45 to 3.99%, 0.26 to 5.88%, 0.88 to 2.85%, 0.26 to 1.96% and 72.63 to 82.70% respectively on wet weight basis. Biochemical analysis revealed remarkable temporal variations in the percentage of biochemical components of the species. Pearson’s product-moment correlation coefficient indicated that water quality parameters (temperature, salinity and pH) and biochemical compositions of M. meretrix had different levels of correlations among themselves.Protein and fiber contents were moderately positively correlated with pH (r = 0.515 and 0.495 respectively) but moisture content was moderately negatively correlated with pH (r = -0.484). Protein exhibited strongpositive correlation with ash content (r = 0.856) and strong negative correlation with carbohydrates (r = -0.800). Moderate positive correlation was found between protein and lipid (r = 0.596). Protein, lipid, ash and fiber contents had moderate negative correlations with moisture content (r = -0.542, -0.641, -0.503 and -0.423 respectively). Overall, the study revealedthat Asian hard clam is an excellent source of several nutrients and the information furnished could be useful to the fishery managers for harvesting and marketing of M. meretrix in a particular season of the year based on the consumers’ specifications.

Non-native Corbicula fluminea (Müller, 1774) (Bivalvia, Veneroidea) in Central Italy: do the waters pumped by Reclaimed Agencies may have a role in spreading through translocation?

Non-native Corbicula fluminea (Müller, 1774) (Bivalvia, Veneroidea) in Central Italy: do the waters pumped by Reclaimed Agencies may have a role in spreading through translocation?

Benzotriazole UV stabilizer-induced genotoxicity in freshwater benthic clams: A survey on apoptosis, oxidative stress, histopathology and transcriptomics.

Benzotriazole UV stabilizer-329 (UV-329) is frequently detected in various environmental and biological matrices. However, the toxicity effect on freshwater benthos induced by UV-329 has rarely been described. In this study, genotoxicity, apoptosis, oxidative stress, histopathological alterations, siphoning behavior, and bioaccumulation in the gill and digestive gland of Corbicula fluminea exposed to UV-329 at 10, 100, and 1000 μg/L for 21 days were investigated. Toxicity screening using transcriptomics confirmed that UV-329 preferentially stimulated cellular process-related pathways including gap junctions, apoptosis, phagosomes and necroptosis. The transcript levels of a large number of apoptosis genes were significantly upregulated. This apoptosis mechanism was further confirmed by the fact that UV-329 exposure significantly increased the percentage of apoptotic cells, activated caspase-3, -8, and -9, and affected the antioxidant enzyme activities. Following exposure to 1000 μg/L UV-329, significant histological alterations were reflected in the corrosion of cilia, cellular swelling of epithelial cells in the gills, degeneration of digestive tubules, and necrosis of epithelial cells in the digestive glands. These results may aid in elucidating the toxicity mechanism of UV329 in bivalves and evaluating the hazards of UV-329 in benthic ecosystems.

Lead Uptake of the Asian Clam (Corbicula fluminea), Nile Tilapia (Oreochromis niloticus) and its Parasite (Acanthogyrus sp.) in Yambo Lake, Laguna, Philippines

The contamination of heavy metals in the aquatic environment poses a threat due to its persistence and potential accumulation in aquatic life forms. In order to detect such pollution, the use of organisms as bioindicators was explored. This study investigated the use of fish acanthocephalan parasites as bioindicator of lead (Pb) in a semi-pristine Yambo Lake in San Pablo, Laguna, Philippines. Lake water samples, wild Nile tilapias (Oreochromis niloticus), its acanthocephalan parasites (Acanthogyrus sp.), and Asian clams (Corbicula fluminea) were collected and subjected to Pb concentration detection through heavy metal analysis. Higher accumulated mean concentration levels of Pb is recorded in Acanthogyrus sp. (10.13 mg kg-1), followed by the fish host tissues: liver (6.19 mg kg-1), intestine (2.80 mg kg-1), and muscle (0.75 mg kg-1). An established bioindicator, C. fluminea, only accumulated an average of 0.16 mg kg-1 Pb in its soft tissues. The bioaccumulation capacity of Acanthogyrus sp. to the fish host and water samples were 35 times higher than the liver, 190 times the intestine and 211 times than the muscle. Furthermore, the accumulated Pb in the parasite was 3,015 times higher than C. fluminea in lake water. Among all samples analyzed, Acanthogyrus sp. showed the highest accumulation capacity. These findings provide useful information to the bio indicator potential of this parasite, and that local environment authorities can utilize its sensitivity to detect and monitor traces of heavy metals even in less polluted aquatic environments.

Freshwater Clam Extract Attenuates Indomethacin-Induced Gastric Damage In Vitro and In Vivo.

Contemporary pharmacological studies have reported that freshwater clam (Corbicula fluminea) can provide a broad spectrum of bioactivities, including antioxidant, anticancer, antihypertensive, hepatoprotective, and hypocholesterolemic effects. The aim of this study was to evaluate the gastroprotective effects of water extract of freshwater clam (WEC) on indomethacin (IND)-induced gastric mucosal cell damage in vitro and gastric ulcer in vivo. The cell viability of rat gastric mucosa RGM-1 cells was markedly decreased by 0.8 mM of IND treatment, and pre-treated with various concentration of WEC significantly restored IND-induced cell damage in a dose-dependent manner. WEC also significantly attenuated the elevated reactive oxygen species (ROS) levels, inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) expression, and nuclear factor-κB (NF-κB) p65 nuclear translocation induced by IND. In the in vivo study, IND caused severe gastric ulcer in Wistar rats, while WEC pretreatment effectively reduced the ulcer area and edema in the submucosa. We found that WEC significantly restored glutathione (GSH) content in gastric mucosa in a dose-dependent manner (p < 0.05). The reduction of prostaglandin E2 (PGE2) caused by IND was also improved with higher doses of WEC administration. Moreover, the overexpression of COX-2, iNOS, and tumor necrosis factor-α (TNF-α) proteins in gastric mucosa was downregulated by administration of WEC. Consequently, WEC can be used as a potential nutritional supplement to improve NSAIDs-caused gastric mucosal lesions.

Application of DNA Metabarcoding for Identifying the Diet of Asian Clam (Corbicula fluminea, Müller, 1774)

Corbicula has often been reported as one of the most invasive freshwater species in the world. It plays an important role in the food chains of brackish water zones in Korea, where it is predominant. However, detailed information on the Corbicula diet is still lacking. The purpose of this study was to identify the potential prey of Corbicula fluminea in the Seomjin River using a DNA metabarcoding approach, as very little is known about its feeding selectivity in natural conditions. A survey was conducted at two study sites (1 and 2) in the Seomjin River in November 2021. The two sites were selected based on increasing salinity gradient. The dominant operational taxonomic unit in the pseudofeces and gut content of C. fluminea was Microcyclops varicans (Copepoda) and Oncorhynchus mykiss (Fish), respectively. The alpha diversity at site 1 was higher than that at site 2. More diverse potential prey species were identified at the site with low salinity (i.e., site 1). The utilization of this method is strongly recommended for determining specific predator–prey relationships in complex estuarine ecosystem.

Population Parameters of Asiatic Hard Clam, Meretrix meretrix (Bivalvia: Veneridae), in Panguil Bay, Philippines

Asiatic hard clam (Meretrix meretrix) is abundant and artisanally harvested in Panguil Bay, Philippines. Information about its current status through stock assessment is vital to support management measures. In this study, estimation of the population parameters of the clam was done using FiSAT II software from May 2018 to April 2019. A total of 2,760 clams were collected and analyzed. The length-weight relationship showed negative allometric growth. The asymptotic length (L∞) and growth coefficient (K) of the von Bertalanffy growth formula for M. meretrix were estimated at 40.95 mm and 0.71 year-1, respectively. The estimated growth performance index (φ’) was 3.07. The predicted maximum life span (tmax) of the clam was 6.47 years. Recruitment occurred throughout the year except for April and was bimodal. Estimated total mortality (Z) was 3.18 year-1, fishing mortality (F) at 1.96 year-1, natural mortality (M) at 1.22 year-1, and exploitation level (E) was 0.62. High recorded fishing and exploitation rate can indicate that the M. meretrix stock in Panguil Bay experiences overexploitation that demands immediate sustainable management.

Structural characteristics and ameliorative effect of a polysaccharide from Corbicula fluminea industrial distillate against acute liver injury induced by CCl4 in mice

Corbicula fluminea distillate as an important industrial by-product of C. fluminea during steaming process is rich in amino acids, proteins and polysaccharides, showing potential hepatoprotective effect. In this study, a polysaccharide (CFDP) was obtained from C. fluminea distillate by three-phase partitioning combined with (NH4)2SO4 precipitation at a saturation of 60 %. The structural characteristics, antioxidant activity in vitro, and hepatoprotection against mice CCl4-induced acute liver damage of CFDP were studied. Results demonstrated that CFDP was a water-soluble homogenous polysaccharide predominantly comprising glucose (>98 %), with a weight-average molecular weight of 1.4 × 107 Da, and exhibiting potent antioxidant benefits in vitro. CFDP had a backbone of (1 → 4)-α-d-glucopyranosyl (Glcp) and a small amount of (1 → 4, 6)-α-D-Glcp. The branch formed at C-6 comprised by (1→)-α-D-Glcp and (1→)-α-D-N-acetylglucosamine. CFDP possessed excellent hepatoprotective activity against acute liver damage caused by CCl4 in mice, mainly by ameliorating weight reduction and organ injures, alleviating hepatic function and serum lipid metabolism, suppressing oxidative stress and inflammatory responses, as directly verified by histopathological examination. Moreover, CFDP improved gut microbiota by up-regulating the relative abundance of total bacteria and probiotics such as Firmicutes, Bacteroidete, Rumminococcaceae, Lactobacillaceae, accompanied by promoting short chain fatty acid production. Therefore, our findings indicated that CFDP can be developed as a healthy food supplement for the prevention of chemical livery injury.

Batten down the hatches: Opportunities to protect Alaska from biological invasions through watercraft trade and traffic

Invasive species are spreading into northern latitudes and threatening food and water security. Alaska’s aquatic environments support some of the world’s most productive wild salmon fisheries. Yet, the influx of invasive species increases the strain on the ecosystems, cultures, and economies that depend on these fisheries. Especially worrisome is the potential transmission of aquatic invasive species (AIS) such as zebra mussels (Dreissena polymorpha), quagga mussels (Dreissena bugensis), or Asian clams (Corbicula fluminea) through the trade and traffic of recreational watercraft from AIS-infested regions. Since neither invasive mussels nor clams have been found in Alaska waters, there is opportunity to prevent introductions of invasive molluscs and avoid catastrophic impacts to some of the world’s last intact ecosystems. To date little data are available to guide human response to reducing the risk of transmitting freshwater AIS that affect critical natal habitat for Alaska’s salmon fisheries. This study triangulated existing data on watercraft registrations and inspections with key informant interviews to establish a first estimate of introduction rates for watercraft-related AIS. Results show that at least 129 used and motorized watercraft are estimated to enter Alaska annually from dreissenid-infested regions with an estimated 47 reaching Alaska freshwater uninspected. These watercraft are entering Alaska through both land and marine pathways. The study points toward the need for a collaborative response among state, federal, tribal, and local agencies, and watercraft owners to devise effective prevention. Response opportunities include inspections and decontaminations at critical control points, and an increased outreach and education campaign for watercraft users. Policy implications for salmon fisheries are discussed should AIS become established in Alaska. Also, the costs, and the long-term sustainability of a prevention program are discussed.

New insights into the mechanism of ammonia toxicity: Focus on Cactus

The NF-κB signaling pathway is the most critical pathway in innate immunity. IκB (Cactus) is the primary cytoplasmic inhibitor of NF-κB (Dorsal). In this study, we found that ammonia exposure could significantly induce the expression of Cactus, in a dose-dependent manner in different tissues, with the highest expression in the gill of Corbicula fluminea. The expression pattern-related elements (Tube and Dorsal) in the NF-κB signaling pathway were also analyzed, showing significant up-regulation in 48 h. There was an inhibitory effect between up-regulated Cactus and Dorsal in 72 h, which may regulate Dorsal as a negative feedback pathway function to control the expression of pro-inflammatory cytokines (IL-1β, IL-6, and TNF-α). Besides, through molecular docking simulation, we found that the Cactus could be directly activated by NH3, complementing the regulatory mechanism of the Cactus. To further test our hypothesis, the levels of pro-inflammatory cytokines decreased after adding PDTC (the antioxidant of Cactus/IκB), suggesting that PDTC can prevent the degradation of Cactus, inhibit Dorsal translocating into the nucleus, and activate the pro-inflammatory cytokines. This revealed the inhibitory effect of Cactus on activating Dorsal/NF-κB factors in the NF-κB signaling pathway. Thus, we suggested that the Cactus is an essential regulator of ammonia-activated inflammation in C. fluminea, which was reported to be activated only by bacteria and immune stimulators. Our study provides a new perspective on the mechanism of ammonia toxicity in invertebrates.

Effect of Asian clam shells on aquatic fauna in an artificial ditch

Effect of Asian clam shells on aquatic fauna in an artificial ditch

Declines in freshwater mussel density, size and productivity in the River Thames over the past half century.

A pioneering, quantitative study published in Journal of Animal Ecology in 1966 on freshwater mussel populations in the River Thames, UK, continues to be cited extensively as evidence of the major contribution that mussels make to benthic biomass and ecosystem functioning in global river ecosystems. Ecological alteration, as well as declines in freshwater mussel populations elsewhere, suggest that changes to mussel populations in the River Thames are likely to have occurred over the half century since this study. We resurveyed the site reported in Negus (1966) and quantified the changes in mussel population density, species composition, growth patterns and productivity. We found large declines in population density for all unionid species. The duck mussel Anodonta anatina decreased to 1.1% of 1964 density. The painter's mussel Unio pictorum fell to 3.2% of 1964 density. The swollen river mussel Unio tumidus showed statistically nonsignificant declines. In contrast to 1964, in 2020 we found no living specimens of the depressed river mussel Pseudanodonta complanata (classified as Vulnerable by the IUCN Red List) but found new records of the invasive, nonnative zebra mussel Dreissena polymorpha and Asian clam Corbicula fluminea. Additionally, we found strong decreases in size-at-age for all species, which now grow to 65-90% of maximum lengths in 1964. As a result of reduced density and size, estimated annual biomass production fell to 7.5% of 1964 levels. Since mussels can be important to ecosystem functioning, providing key regulating and provisioning services, the declines we found imply substantial degradation of freshwater ecosystem services in the River Thames, one of the UK's largest rivers. Our study also highlights the importance to conservationists and ecologists of updating and validating assumptions and data about wild populations, which in the present era of anthropogenic ecosystem alteration are undergoing significant and rapid changes. Regular population surveys of key species are essential to maintain an accurate picture of ecosystem health and to guide management.

Susceptibility of invasive Asian clams to Chaetogaster limnaei: effect of parasite density and host size on infection dynamics

Susceptibility of invasive Asian clams to Chaetogaster limnaei: effect of parasite density and host size on infection dynamics

Density, morphometric characteristics and distribution pattern of Asiatic hard clam (Meretrix meretrix) in Karang Gading estuary, Deli Serdang District, Indonesia

Abstract. Rimelahas WL, Mulya MB, Barus TA. 2022. Density, morphometric characteristics and distribution pattern of Asiatic hard clam (Meretrix meretrix) in Karang Gading estuary, Deli Serdang District, Indonesia. Biodiversitas 23: 5210-5216. Asiatic hard clam (Meretrix meretrix) has a wide distribution, ranging from mangrove forest areas in the Indo-Pacific to mangrove swamp areas in South America. In Indonesia, clam is found on the island of Sumatra, one of which is in the estuary waters of the Karang Gading Wildlife Sanctuary, Deli Serdang District, North Sumatra, Indonesia. In this area, fishermen are often found catching clams. The catch of clams in addition to its own consumption is also widely sold in traditional markets. The existence of clam capture activities carried out continuously can threaten the sustainability of this commodity in nature. This study aims to find out the density, morphometric characteristics, distribution patterns and the relationship of clam density with aquatic physicochemical. Sampling was carried out in July-August 2021 in the estuary waters of Karang Gading Wildlife Sanctuary Deli Serdang District using a purposive sampling method. Sampling was done by using a clam rake with a radius length of 35 cm. At each station, 5 sampling points were determined and 3 dredgings were carried out at each point which is done 2 times with 30-day intervals at 07.00-11.00 WIB. The results concluded that the highest density of clam is found in station I with a value of 3896 ind/m2, the pattern of growth of the clam at each station is negative allometric, the pattern of the group and uniform clam distribution, and the correlation of physical and chemical factors of the waters with the density of the clam shows that phosphate has a very strong correlation to the density of the clam, while the temperature correlates moderately with the density of the clam.

Distribution and Status of Freshwater Mussels in the Bear Creek Watershed, Mississippi

Bear Creek is a tributary of the Tennessee River in northwestern Alabama and northeastern Mississippi. The watershed supports a diverse freshwater mussel assemblage including several species of conservation concern. We conducted a mussel survey at 55 sites in the Mississippi portions of Bear Creek and its largest tributary, Cedar Creek, during September and October 2020. We found a total of 30 species, of which 25 were represented by live individuals. The invasive Asian Clam, Corbicula fluminea, was widespread in the watershed, but we found no evidence of Zebra Mussel, Dreissena polymorpha. Notable species found live included two federally endangered species, Cumberlandian Combshell, Epioblasma brevidens and Slabside Pearlymussel, Pleuronaia dolabelloides; one federally threatened species, Rabbitsfoot, Theliderma cylindrica; and two state endangered species. In addition, we report the first documented occurrence of the Mountain Creekshell, Villosa vanuxemensis, in Mississippi. Mussel abundance and species richness were low at most sites in the watershed, but the upper portion of Bear Creek had the highest mussel abundance and species richness. We compare our results with previous surveys in the watershed and discuss conservation issues pertinent to the Bear Creek mussel fauna.

Efectos de las actividades antrópicas sobre parámetros metabólicos en un bivalvo invasor y otro nativo en el tramo inferior del río Paraná

The relationship between anthropogenic pollution, geochemistry and natural dynamics of freshwater ecosystems determine the spatial and temporal patterns of water quality. Human activities and the introduction of exotic species are the main causes of the decrease in biological diversity. The introduction and spread of the invasive bivalve Corbicula fluminea endangers the presence of the native bivalve Diplodon delodontus. Through oxidative stress indicators, it is possible to quantify the response of organisms to changes in physical-chemical, natural and/or anthropogenic variables. Therefore, the objective was to interpret the effect of changes in physical-chemical variables, contaminants and/or xenobiotics on the metabolic responses of C. fluminea and D. delodontus on the Paraná de las Palmas river. Randomly, we established a sampling point to collect individuals (60 of invasive and 10 of native bivalve) for the assembly of 10 cages by species and placement site in September 2018. In June and September 2019, five cages of each species were extracted at random. In water, physical-chemical parameters and metals were measured, and in the organs of both species, protein concentration, glycogen, lipid damage, reduced glutathione content, enzymatic activity of catalase and glutathione-S-transferase. In general, the physical-chemical and metal parameters increased significantly from June to September. Metals exceeded freshwater quality guideline levels for the protection of aquatic life. In relation to the changes in these variables, the metabolic parameters differed between organs and species from June to September. The gills and digestive gland of C. fluminea showed higher metabolic responses and faster than D. delodontus. The study of invasive and native species through the measurement of multiple variables is a useful tool to characterize the environment, with application prospects in water quality monitoring and conservation studies.

Impacts of high-hydrostatic pressure on the organoleptic, microbial, and chemical qualities and bacterial community of freshwater clam during storage studied using high-throughput sequencing

This study was to determine the effects of high pressure processing (HPP; 200–600 MPa for 3 min) on the microbial, chemical, and organoleptic properties and the bacterial flora of freshwater clam (Corbicula fluminea) during cold storage. The results indicated that with an increase in pressure, the expanding rate, moisture content, shucking ratio, pH, lightness (L*), and whiteness (W) increased, whereas redness (a*), yellowness (b*), aerobic plate count (APC), psychrotrophic bacteria count (PBC), coliform, and Salmonella spp. decreased. In addition, HPP treatment of >300 MPa on samples significantly retarded the increases in APC, PBC, coliform, Salmonella spp., and total volatile basic nitrogen and a drop in pH during cold storage. Results of organoleptic analysis showed that HPP at 300 and 500 MPa prolonged the shelf life from 6 days (control group) to 9 days and 12 days, respectively. High-throughput sequencing (HTS) revealed that HPP considerably changed the spoilage microflora in samples after 15 days storage and delayed the spoilage process. These results demonstrate that pressurisation at least 300 MPa for 3 min on clam samples were able to reach 100% shucking, inactivate microbial growth, and retard quality loss, while they effectively extended shelf life of freshwater clam during cold storage.

A taxonomic reassessment of native and invasive species ofCorbiculaclams (Bivalvia: Cyrenidae) from the Russian Far East and Korea

AbstractCurrently, the validity of many nominal bivalve species of the genus Corbicula endemic to the Russian Far East and South Korea needs a critical reassessment. In this study, we clarify the taxonomic status of Corbicula species of this area based on a combination of molecular genetic, conchological and anatomical data. According to our results, four Corbicula lineages, corresponding to the nominal species Corbicula japonica, Corbicula elatior, Corbicula leana and Corbicula fluminea, can be delineated in samples collected in the Primorye and Khabarovsk regions of Russia and South Korea. Two species endemic to the Russian Far East (i.e. Corbicula finitima and Corbicula lindholmi) are considered here as junior synonyms of the species C. japonica, which is widely distributed in estuarine habitats around the Japanese Archipelago, Sakhalin Island, southern Kurile Islands, Primorye and Khabarovsk regions, Korean Peninsula and China. Three nominal species described from the Lower Amur basin (Corbicula amurensis, Corbicula nevelskoyi and Corbicula sirotskii) appeared to be synonyms of C. elatior, whose range covers the Korean Peninsula, Primorye and Khabarovsk regions and, perhaps, China. We delineated several colour morphs of C. fluminea and C. japonica. The distinctness between these colour morphs can be attributed to both heritable and environmental factors.

Broadscale distribution, abundance, and habitat associations of the invasive Asian clam (Corbicula fluminea) in the lower Columbia River, USA

AbstractThe Asian clam, Corbicula fluminea, is an invasive freshwater bivalve that has established populations across the globe and is known to have deleterious effects on natural and human systems. Yet, despite being present in the Columbia River (CR) for nearly a century, little is known about this invader's basic biology and ecology in this large river system. Thus, we undertook a field study to assess its (i) broadscale distribution and abundance, and (ii) associations with habitat characteristics in the lower CR. During 2019–2020, C. fluminea were collected from 27 shore‐based stations spanning 481 river kilometers of the lower CR, along with several habitat characteristics (bank slope, temperature, dissolved oxygen, pH, salinity, conductivity, chlorophyll‐a concentration, and sediment composition and % organic matter [OM]). C. fluminea abundance ranged from 0 to 430 ind. m−2. Most sites with abundances &gt;100 ind. m−2 were located downstream of Bonneville Dam, whereas most sites with abundances &lt;100 ind. m−2 were located upstream. Generalized linear models predicting the abundance of C. fluminea indicated significantly positive correlations with water temperature and % sand, and negative correlations with bank slope and sedimentary % OM. We also reviewed the global literature on abundance and habitat associations of C. fluminea and compared this with our own results. Our investigation represents the greatest spatial extent at which C. fluminea has been studied in the CR and our results provide a better understanding of the basic biology and ecology of this global invader, as well as provide natural resource managers with information on habitat conditions favorable for this invasive bivalve within temperate river ecosystems.