Clam Corbicula Research Articles

Impact of habitat engineering by invasive Corbicula clams on native European unionid mussels

Biological invasions cause biodiversity erosion on a global scale. Invasive species spreading beyond their natural range compete with native fauna for food and space, push native species to suboptimal habitats, impairing their behaviour and thus limiting their occurrence. Freshwater ecosystems are especially vulnerable to biological invasions and their ecological and economic impacts. The invasive Asian clams (Corbicula spp.), due to their opportunistic life style, can occur at densities of thousands ind. m−2. They act as ecosystem engineers transforming bottom substrata through accumulation of shells. Our goal was to determine the effect of substratum modification by living Corbicula and their shells on substratum choice and behaviour of Unio tumidus and Anodonta anatina, two European freshwater mussel species of the highly imperilled Unionidae family. We assessed their substratum selection in pairwise choice tests (pure sand vs. sand modified by living Corbicula or their shells, sand modified by shells vs. living Corbicula). Next, we tested locomotion and burrowing of unionids on pure substratum and substrata modified by Corbicula. Unionids avoided sand modified by living Corbicula and their empty shells, not distinguishing between these two types of substratum modification. In the presence of Corbicula, their burrowing was shallower or it took them longer to obtain the same depth as in the pure sand. Additionally, on sand modified by Corbicula shells, we observed a locomotion increase (U. tumidus) or slowing down (A. anatina). Our research showed a novel mechanism of negative impact of Corbicula on unionids, consisting in pushing them away from their optimal habitats. This may contribute to their habitat loss and future declines in invaded ecosystems.

Opening the black box of the invasion of Corbicula clams (Bivalvia, Corbiculidae) in South America: a genetic and morphological evaluation

Opening the black box of the invasion of Corbicula clams (Bivalvia, Corbiculidae) in South America: a genetic and morphological evaluation

Genetic and Morphological Characterization of the Invasive Corbicula Lineages in European Russia

Despite the full attention of malacologists to the study of Corbicula clams, stimulated mainly due to their high invasive potential and unique breeding system, studies based on an integrative taxonomic approach to identify various invasive lineages of this genus in European Russia are still limited. Our fieldwork was conducted in the Don, Volga, and Caspian Sea basins. In total, four distinct morphotypes belonging to the European forms R, Rlc, S, and “Int” of Corbicula clams were distinguished. According to our molecular genetic data, two Corbicula lineages, relevant to the nominal species Corbicula fluminea and C. fluminalis, can be defined. We observed a discrepancy between mtDNA haplotypes and morphological features for all individuals that were sampled from the Don and Kura Rivers. Identified mismatch may be due to the androgenetic reproduction of Corbicula that leads to cytonuclear inconsistencies. The 28S rRNA polymorphism in C. fluminea and C. fluminalis from studied localities was recorded. This occurrence is perhaps due to hybridization events between forms R, S, and Rlc. The biogeographic origins of Corbicula invasive lineages are discussed. Corbicula fluminalis (FW17, form S) has been detected for first time in the native range, namely in Azerbaijan, Tajikistan, Turkey, and Myanmar. We assume that the invasion of C. fluminalis into reservoirs and watercourses of the Caspian Sea basin (Republic of Dagestan and Stavropol Krai of Russia) was from Western Asia and Transcaucasia, and the introduction of C. fluminea to the Don and Volga River basins was from unspecified European countries.

Differences in substratum preferences and behaviour within the invasive Corbicula species complex

Abstract Clams from the Corbicula species complex of Asian origin are invasive all over the world, currently extending their distribution to waters of the natural thermal regime in Central European areas. Features linking the clams to their habitats in newly invaded areas have not been fully examined. These include substratum preferences and mobility, which may be key to determining potential niche overlap with native bivalves and gaining a better knowledge of their potential active dispersal and impact. Therefore, our aim was to determine the substratum preferences, horizontal locomotion and burrowing behaviour of three Corbicula morphospecies from Poland, Central Europe: two populations of undetermined Corbicula sp. from an artificially heated habitat and water of the natural thermal regime (cold water), as well as Corbicula leana, and Corbicula fluminea (from artificially heated and cold water, respectively). To determine the preferred substratum range, we used pairwise choice tests with a range of muddy, sandy, and gravelly substrata, as well as zebra mussel shells. Then, we conducted behavioural observations (locomotion and burrowing) by CCTV cameras on substrata found as preferred and non‐preferred by clams. All morphospecies preferred fine‐grained over coarser substrata. C. fluminea from cold water had the widest range of substratum preferences. By contrast, C. leana from artificially heated water and Corbicula sp. from cold water showed the narrowest substratum preferences and spent the longest time deeply burrowed. The longest duration of burrowing activity was noted on non‐preferred coarser substrata, which may indicate difficulties in burrowing. On non‐preferred coarse substrata, C. fluminea (cold water) crawled more than the other morphospecies. Our results show that sediment preferences and behaviour (burrowing and locomotion) differ among various Corbicula morphospecies in Europe, probably also varying their invasive potential. This knowledge is important for determining the overlap of habitat preferences of non‐native Corbicula clams with native bivalves, which is critical for determining potential competition strength, impact, and/or displacement. Our results also indicate that habitats with fine sediments could be more threatened by Corbicula invasions.

Infection of Corbicula clams by trematode cercariae in Myanmar

A few studies on parasites associated with Corbicula clams are currently available. Here, we report on the first DNA-based and histological identification of cercariae of the trematode Prosorhynchoides sp. (Digenea: Bucephalidae) in C. fluminea and C. leana from Myanmar. The cercariae of Prosorhynchoides sp. were discovered in the foot tissue of these clams. The mean body length of cercaria is 132.7 ± 10.0 µm, while the mean tail stem length is 26.1±1.4 µm.

Temperature drives reproductive activity in a rare trioecy population of Corbicula clams

Temperature drives reproductive activity in a rare trioecy population of Corbicula clams

Spectroscopic studies for identifying the chemical states of the periostracum of the Corbicula species in Lake Biwa

Corbicula clam shells consist of thin periostracum and calcareous layers made of calcium carbonate (CaCO3). Depending on habitat conditions, the shell exhibits various colorations, such as yellow, brown, and black. The chemical state of the periostracum of the Corbicula species in Lake Biwa was studied by X-ray absorption fine structure (XAFS) and Raman scattering spectroscopies. Fe K-edge X-ray absorption near edge structure (XANES) revealed that the Fe3+ intensity increases as the color of the shell changes from yellow to black. Raman spectra suggested that quinone-based polymers cover the yellow shell, and the black shell is further covered by dihydroxyphenylalanine (DOPA) rings of amino acid derivatives. From Fe K-edge extended X-ray absorption fine structure (EXAFS), it was found that Fe3+ in the periostracum was surrounded by five to six oxygen atoms with an average Fe-O ligand distance of 2.0 Å. Accordingly, a tris-DOPA-Fe3+ complex is formed, which is responsible for the periostracum’s black color.

Associations of mayfly larvae with Corbicula clams

Abstract Currently, the parasitic and endosymbiontic fauna of Corbicula clams remain poorly studied throughout their range. Here, using samples from the Mekong basin, we describe two Symbiocloeon species new to science: Symbiocloeon corbiculinus sp. nov. and Symbiocloeon laoensis sp. nov. Our results and a review of available published data indicate that freshwater bivalve-associated mayflies are narrow host specialists, being associated with one or a few closely related species of freshwater bivalves. The bivalve-associated mayfly larvae have several specific morphological traits compared with free-living species, which include a reduction of integument chitinization and a significant reduction of the surface structures on segments. An increase in area of the respiratory surface of larval tergalia was also recorded. The possible positive and negative effects of mayflies on the clam hosts are discussed. This study is an example of the many possible hidden associations between aquatic species that remain to be described.

Salinity appears to be the main factor shaping spatial COI diversity of Corbicula lineages within the Chinese Yangtze River Basin

AbstractAimTo date, few studies have examined the phylogenetics of Corbicula clams in their native range and the environmental parameters influencing their distribution, although this could provide great insights into the biological adaptation and invasion dynamics of Corbicula clams. We sought to identify the genetic lineages of native Corbicula clams and elucidate the environmental factors shaping the distributions of identified lineages.LocationChina, mainly the Yangtze River Basin.MethodsThe alignment comprised 558 COI sequences including samples from China and 222 COI sequences from published studies. This dataset was used to generate phylogenetic trees and compare population diversity. We used dbRDA method to assess the relationship between these COI data and environmental factors measured to identify the important factors affecting Corbicula's distribution.ResultsThe COI phylogenetic tree delineated the monophyly of 3 major COI clades and 77 distinct COI haplotypes in the Yangtze River Basin. The invasive lineage C/S (FW17) was not identified in our sampling in China, while invasive lineages A/R (FW5 = Hap6), B (FW1 = Hap17) and Rlc (FW4 = Hap43) were identified, abundant and widely distributed in the middle and lower reaches of Yangtze River. Focusing on populations from Yangtze River Basin, both the COI haplotype and nucleotide diversity in the lakes along the Yangtze River increased with longitude, except for the river mouth population. The AMOVA tests showed significant differentiation between the middle and lower reaches of the Yangtze River and among populations. The dbRDA results suggested that the parameter chloride explained most of the spatial COI haplotype distribution variation in the Yangtze River Basin, with the three invasive lineages tolerating broad fluctuations of salinity (chloride levels ranging from 4 to 60 mg/L).ConclusionsThe Corbicula COI haplotypes found within the Yangtze River Basin had distinct distribution preferences, with the invasive androgenetic lineages being the most abundant and widely distributed. Genetic diversity was higher in this native region than in invaded areas in Europe and America, while it decreased with increasing distance from the river mouth. Salinity appeared to be the main environmental factor shaping the COI haplotype distribution of Corbicula lineages within their native range.

Substantial genetic mixing among sexual and androgenetic lineages within the clam genus Corbicula

“Occasional” sexuality occurs when a species combines clonal reproduction and genetic mixing. This strategy is predicted to combine the advantages of both asexuality and sexuality, but its actual consequences on the genetic diversity and species longevity are poorly understood. Androgenesis, a reproductive mode in which the offspring inherits its entire nuclear genome from the father, is often reported as a strictly clonal reproductive mode. Androgenesis is the predominant reproductive mode within the hermaphroditic, invasive lineages of the mollusk genus Corbicula. Their ability to reproduce clonally through androgenesis has been determinant in their invasive success, having colonized during the 20th century American and European freshwater systems, where they became notorious invaders with a widespread, global distribution. However, in androgenetic Corbicula clams, occasional genetic mixing between distinct lineages has also been observed when the sperm of one lineage fertilizes the oocyte of another one. Because of these occasional introgressions, the genetic relationships between Corbicula species remained unclear, and the biogeographic origins of the invasive androgenetic lineages have been challenging to identify. To address these issues, we analyzed the patterns of allele sharing for several nuclear and mitochondrial molecular markers among Corbicula individuals collected across both the native and invasive range. Our results show the occurrence of an allelic pool encompassing all Corbicula freshwater species worldwide, including sexual and androgenetic ones, which highlights the substantial genetic mixing within this genus. However, the differences in allele sharing patterns between invasive lineages, and the low diversity within each lineage, suggest recent, distinct biogeographic origins of invasive Corbicula androgenetic lineages. Finally, the polyploidy, high heterozygosity, and hybrid phenotypes and genotypes found in our study probably originated from hybridization events following egg parasitism between distinct Corbicula lineages. This extensive cross-lineage mixing found in Corbicula may generate nuclear diversity in an otherwise asexually reproducing species.

Reproductive Mode of Corbicula tobae (Martens, 1900): Brooding and Larval Morphology in Lake Toba (Indonesia)

Currently, the reproductive mode of the Indonesian endemic species Corbicula tobae from Lake Toba is yet to be investigated. In this study, we describe, for the first time, the reproductive mode of this endemic species based on a series of topotype specimens, combining anatomical and histological data. According to our data, C. tobae is a dioecious species, incubating D-shaped larvae in the inner demibranchs and having monoflagellate sperm. The head of the C. tobae spermatozoon differs from those of other Indonesian species of Corbicula by having the smallest length. A histological investigation of C. tobae gills revealed that the inner demibranch has larger interlamellar spaces compared with the outer demibranches. Our study highlights several specific reproductive traits may have evolved in narrowly endemic Corbicula clams within their native ranges.

Diffusive methane burst during a blue tide, wind-driven event in a meromictic lake

Strong stratification has formed in Lake Abashiri, a typical meromictic lake in Hokkaido, in the subarctic zone in Japan. When the anoxic water of the lower layer is upwelled to the surface by a strong wind, fish and corbicula clams die due to a lack of dissolved oxygen. This event is called as blue tide. It was observed that the dissolved methane in the lake decreased more than 100 t after the blue tide which occurred in 2008. This is the discovery of the phenomenon that a large quantity of methane diffuses to the atmosphere caused by upwelling of anoxic water which contains dissolved methane. We named the event as “methane burst”. It is also the first report that the wind-driven upwelling is reproduced using a numerical analysis code and the methane burst is analyzed. During this blue tide, the methane flux was approximately 170 times greater than usual.

West-to-East Heavy Metal Transport in Bottom Sediments Affecting the Toxicity Indices of Asiatic Clam (Corbicula Fluminea) in Laguna De Bay, Philippines

West-to-East Heavy Metal Transport in Bottom Sediments Affecting the Toxicity Indices of Asiatic Clam (Corbicula Fluminea) in Laguna De Bay, Philippines

Dissecting the chromosome-level genome of the Asian Clam (Corbicula fluminea)

The Asian Clam (Corbicula fluminea) is a valuable commercial and medicinal bivalve, which is widely distributed in East and Southeast Asia. As a natural nutrient source, the clam is rich in protein, amino acids, and microelements. The genome of C. fluminea has not yet been characterized; therefore, genome-assisted breeding and improvements cannot yet be implemented. In this work, we present a de novo chromosome-scale genome assembly of C. fluminea using PacBio and Hi-C sequencing technologies. The assembled genome comprised 4728 contigs, with a contig N50 of 521.06 Kb, and 1,215 scaffolds with a scaffold N50 of 70.62 Mb. More than 1.51 Gb (99.17%) of genomic sequences were anchored to 18 chromosomes, of which 1.40 Gb (92.81%) of genomic sequences were ordered and oriented. The genome contains 38,841 coding genes, 32,591 (83.91%) of which were annotated in at least one functional database. Compared with related species, C. fluminea had 851 expanded gene families and 191 contracted gene families. The phylogenetic tree showed that C. fluminea diverged from Ruditapes philippinarum, ~ 228.89 million years ago (Mya), and the genomes of C. fluminea and R. philippinarum shared 244 syntenic blocks. Additionally, we identified 2 MITF members and 99 NLRP members in C. fluminea genome. The high-quality and chromosomal Asian Clam genome will be a valuable resource for a range of development and breeding studies of C. fluminea in future research.

Comparison between mouse bioassay and HILIC-MS/MS for quantification of paralytic shellfish toxin in Japanese basket clams and mussels caught off coastal Osaka Bay in Japan

ABSTRACT The content and composition of paralytic shellfish toxins (PSTs) in Japanese basket clam (Corbicula japonica) and mussels (Mytilus galloprovincialis) from Osaka Bay, Japan, were investigated using a mouse bioassay (MBA) and hydrophilic interaction liquid chromatography-tandem mass spectrometry (HILIC-MS/MS), and the association between toxicity values of MBA and HILIC-MS/MS was verified based on research data. The overall toxicity in Japanese basket clam was lower than that in the mussel. The PSTs of Japanese basket clam and mussel consisted mainly of C1, C2, and gonyautoxins 1–4 (GTX1–4) taking toxins compositional differences as mol%. When multiplying the content of different toxins by the toxic equivalent factor (TEF), C2 and GTX1–4 accounted for more than 90% of total toxicity (MU TEF/g) based on the MU TEF score converted by TEF for the two species. The total content of C2 and GTX1–4 converted to toxicity was significantly correlated with the toxicity determined by MBA for the two species (r 2 > 0.983). This study provides a suitable and ethical monitoring method to investigate toxicity in bivalves contaminated with A. tamarense by analysis of only predominant toxins, along with reducing use of MBA.

Reproduction of the Androgenetic Population of the Asian Corbicula Clam (Bivalvia: Cyrenidae) in the Northern Dvina River Basin, Russia

The Corbicula clam is one of the most successful invaders of aquatic ecosystems and has invaded all continents except Antarctica. The natural dispersion of Corbicula seems to be limited by low winter temperatures that fall below the lower lethal temperatures (0 to +2 °C). However, Corbicula can be found in colder regions, taking refuge in waters heated by thermal power plants. The purpose of this investigation was to study the gonadal histology, reproductive cycle, and the seasonal changes of shell size structure of the Corbicula clam populations in the warm water discharge of the Arkhangelsk thermal power plant (Northwest Russia). Samples were collected monthly from January 2017 to December 2018 and processed using traditional histological and morphological techniques. The number of reproductive periods varied from year to year. It was established that the Corbicula clam has a continuous reproduction period which may be adaptive in unstable environmental conditions. This reproductive strategy is probably aimed at increasing the reproductive success of the population. Our data expand the understanding of reproductive features of the Corbicula clam in harsh environmental conditions. These results could be applied to control, monitoring, and management measures.

Laboratory and field studies on the use of artificial mussels as a monitoring tool of platinum exposure in the freshwater environment

BackgroundThe artificial mussel (AM) is a passive sampling device that was originally developed for monitoring metal concentrations in the marine environment, but is also increasingly used in freshwater environments. The AM consists of a non-permeable Perspex tube, which is closed on both sides with a semi-permeable membrane. The space in between contains Chelex-100 beads, which bind metals. The AM allows the determination of the dissolved, bioaccessible metal fraction in water bodies without killing organisms, as well as environments with unfavorable conditions for living bioindicators. In the present study, the use of the AM was adapted for the monitoring of platinum (Pt) in a freshwater ecosystem.ResultsThe elution of Pt from the Chelex-100 beads was optimized. Two modifications to the original method for the use of AMs are recommended, i.e., washing and separation of the beads through centrifugation and elution with a mixture of 4.5 mL HNO3 and 0.5 mL HCl for approximately 2–3 h to ensure the release of all Pt bound to the beads. Additionally, the uptake kinetics of the AM were determined under laboratory conditions over a wide exposure concentration range (0.1–1000 µg/L) showing highly correlated Pt accumulation in the AMs with the aqueous exposure concentration. For the tested Pt exposure concentrations of 0.1, 1, 10, and 100 µg/L, the Pt concentrations in the AMs increased during the exposure period of 6 weeks. At the highest exposure concentration of 1000 µg/L, the increase stagnated after 3 weeks. To validate the AM in the field, the Pt accumulation of the AM was assessed together with that of freshwater clams (Corbicula fluminalis africana), muscle and liver tissue of the three fish species sharptooth catfish (Clarias gariepinus), common carp (Cyprinus carpio) and Mozambique tilapia (Oreochromis mossambicus), as well as water hyacinths (Eichhornia crassipes) at two sampling sites in the Pt mining area of South Africa.ConclusionResults from the present study showed that the AM is a promising tool to monitor Pt concentrations in the freshwater environment at contaminated sites.

Long-term impacts of nutrient control, climate change, and invasive clams on phytoplankton and cyanobacteria biomass in a large temperate river

Recent studies suggest that climate change, with warmer water temperatures and lower and longer low flows, may enhance harmful planktic cyanobacterial growth in lakes and large rivers. Concomitantly, controlling nutrient loadings has proven effective in reducing phytoplankton biomass especially in North America and Western Europe. In addition, the impact of invasive benthic filter-feeder species such as Corbicula on phytoplankton has largely been overlooked in large rivers, leading to even more uncertainty in predicting future trajectories in river water quality.To investigate how nutrient control, climate change and invasion of benthic filter-feeders may affect phytoplankton biomass and composition, we assembled a large database on the entire water course of the River Loire (France) over three decades (1991–2019). We focus on cyanobacteria to provide an in-depth analysis of the 30-year trend and insights on future possible trajectories. Since 1991, total phytoplankton and cyanobacteria biomasses have decreased 10-fold despite warmer water temperature (+0.23 °C·decade−1) and lower summer flow (−0.25 L·s−1·km−2·decade−1). In the long-term, the contribution of planktic cyanobacteria to total biomass was on average 2.8%. The main factors driving total phytoplankton and cyanobacteria biomasses were total phosphorus (4-fold decrease), the abundance of Corbicula clams (from absence before 1998 to 250–1250 individuals·m−2 after 2010), the duration of summer low flows and the intensity of summer heatwaves. The River Loire constitutes an example in Europe of how nutrient control can be an efficient mitigation strategy, counteracting already visible effects of climate change on the thermal regime and flow pattern of the river. This may hold true under future conditions, but further work is needed to account for the climate trajectory, land and water use scenarios, the risk of enhanced benthic biofilm and macrophyte proliferation, together with the spread of invasive filter-feeding bivalves.

STATUS OF FRESHWATER MUSSELS (UNIONIDAE) OF THE RÍO CONCHOS BASIN, CHIHUAHUA, MEXICO

Before this study, researchers had not systematically surveyed the Rio Conchos, a tributary of the Rio Grande located in northern Mexico, for freshwater mussels. The Texas hornshell, Popenaias popeii, an endangered species under the United States Endangered Species Act, occurs in the main stem of the Rio Grande near its confluence with the Rio Conchos. The Texas hornshell's proximity to the Rio Conchos prompted us to survey to determine whether P. popeii also occurs within the Conchos basin. Additionally, previous researchers described the Conchos disk, Disconaias conchos, from the Rio Conchos but, to date, no one has reported live individuals of this species. The goal of this study was to determine the status of mussels within the Rio Conchos basin and to provide a baseline for future monitoring efforts. We qualitatively surveyed 11 sites within the Rio Conchos basin in May 2018. In total, we found two live individuals of the paper pondshell, Utterbackia imbecillis, at one site in the Rio San Pedro, a tributary of the Conchos River, and as shells of recently live individuals at two sites in the Rio Conchos. We found D. conchos as relict shells only at three sites, two in the Rio Conchos and one in a tributary of the river at Coyame. The lack of live or fresh-dead material suggests that D. conchos is extinct. We also found live individuals of nonnative Asian clams (Corbicula spp.) at 10 sites. Sand and gravel mining, high organic pollution, and inadequate instream flows were evident throughout the basin and might explain the general absence of mussels.

Chemical State Analysis of the Periostracum in the Corbicula Clam Hatched in Lake Biwa

The periostracum of corbicula clams is a unique outermost organic layer secreted from the inner surface of the outer mantle. It records the environmental history of corbicula clams which inhabited Lake Biwa. Two types of corbicula clams, yellowish and blackish shells, were studied with X-ray fluorescence element mapping and S, Fe and Mn K-edge X-ray absorption fine structure (XAFS) spectroscopy. It was revealed that the blackish shells grow in the more reducing environment than the yellowish ones. Main constituent of the periostracum is protein-based material, such as cysteine and methionine. The blackish shells contain much higher amount of Fe and Mn impurities. Fe was accumulated as FeOOH along the growth lines. Sulfur exists exclusively as organic molecules with the functional groups of thiol (-SH), which is oxidized to form disulfide (-SS-) by exposure to the oxidizing environment.