Class Bivalvia Research Articles

Cambrian origin but no early burst in functional disparity for Class Bivalvia.

Both the Cambrian explosion, more than half a billion years ago, and its Ordovician aftermath some 35 Myr later, are often framed as episodes of widespread ecological opportunity, but not all clades originating during this interval showed prolific rises in morphological or functional disparity. In a direct analysis of functional disparity, instead of the more commonly used proxy of morphological disparity, we find that ecological functions of Class Bivalvia arose concordantly with and even lagged behind taxonomic diversification, rather than the early-burst pattern expected for clades originating in supposedly open ecological landscapes. Unlike several other clades originating in the Cambrian explosion, the bivalves' belated acquisition of key anatomical novelties imposed a macroevolutionary lag, and even when those novelties evolved in the Early Ordovician, functional disparity never surpassed taxonomic diversity. Beyond this early period of animal evolution, the founding and subsequent diversification of new major clades and their functions might be expected to follow the pattern of the early bivalves-one where interactions between highly dynamic environmental and biotic landscapes and evolutionary contingencies need not promote prolific functional innovation.

A tale of two paths: The evolution of mitochondrial recombination in bivalves with doubly uniparental inheritance.

In most animals, mitochondrial DNA is strictly maternally inherited and non-recombining. One exception to this pattern is called doubly uniparental inheritance (DUI), a phenomenon involving the independent transmission of female and male mitochondrial genomes. DUI is known only from the molluskan class Bivalvia. The phylogenetic distribution of male-transmitted mitochondrial DNA (M mtDNA) in bivalves is consistent with several evolutionary scenarios, including multiple independent gains, losses, and varying degrees of recombination with female-transmitted mitochondrial DNA (F mtDNA). In this study, we use phylogenetic methods to test M mtDNA origination hypotheses and infer the prevalence of mitochondrial recombination in bivalves with DUI. Phylogenetic modeling using site concordance factors supported a single origin of M mtDNA in bivalves coupled with recombination acting over long evolutionary timescales. Ongoing mitochondrial recombination is present in Mytilida and Venerida, which results in a pattern of concerted evolution of F mtDNA and M mtDNA. Mitochondrial recombination could be favored to offset the deleterious effects of asexual inheritance and maintain mitonuclear compatibility across tissues. Cardiida and Unionida have gone without recent recombination, possibly due to an extension of the COX2 gene in male mitochondrial DNA. The loss of recombination could be connected to the role of M mtDNA in sex determination or sexual development. Our results support that recombination events may occur throughout the mitochondrial genomes of DUI species. Future investigations may reveal more complex patterns of inheritance of recombinants, which could explain the retention of signal for a single origination of M mtDNA in protein-coding genes.

Species Diversity of Bivalves and Gastropods at the Tanjung Rising Coastal, Bangka Belitung Island

Tanjung Rising Coastal, located in Dendang Village, Bangka Belitung Islands, has a large variety of substrates and organisms. One of the types of marine life studied is the Mollusk Phylum including the Bivalve and Gastropod classes. To find out the diversity of Bivalvia and Gastropoda, this study was carried out on Tanjung Rising Coastal, Bangka Belitung Islands. The study was conducted in December 2020-August 2021, using belt transect method with purposive sampling technique. Samples were collected at station 1 with a sandy substrate and station 2 with a muddy substrate. The results of this study found 1,372 individuals from the Bivalvia class consisting of 7 families and 12 species, while from the Gastropod class yielded 2,630 individuals consisting of 5 families and 7 species. The diversity and evenness index at both stations is relatively low which means that there are species that dominate, because both stations have good habitats for the dominating species. In addition, temperature, pH, salinity, depth, and strong currents showed good values for Bivalvia and Gastropoda habitat. In summary, Tanjung Rising Beach is still a good habitat for invertebrate animals, especially Bivalvia and Gastropoda.

Macrofauna Diversity Associated with Mangrove Roots in West Lombok Regency

Mangrove is an ecosystem that has a wealth of macrofauna, which includes plant species and biota associated therein, gastropods and bivalves associated with mangroves as living habitat, shelter, spawning and food supply. The purpose of this study was to determine the diversity of macrofauna associated with mangrove species. This research is a quantitative descriptive research with a survey method. The results showed that the diversity of gastropods and bivalves on the gastropod Cemara beach was 2.05. Bivalvia 1.22. Meanwhile in Bagek Kembar. Gastropods 1.73 and bivalvia 1.32 have relatively low diversity. The results of the analysis using the contingency table at the study site were 8 pairs from the Gastropod class and 4 pairs from the Bivalvia class, these pairs tended to associate at the 5% test level. The macrofauna and mangrove species pairs obtained had a positive association of 6 pairs, namely (Telescopium -Avicennia lanata, Terebralia sulcata -Avicennia lanata, Cerithideacingulata-Rhizophora mucronata, Cerithidea cingulata-Avicennia marina, Cerithideacingulata-Sonneratia caseolaris, Batillaria zonalis -Rhizophora stylosa) whereas in class bivalves there are 4 pairs (Anadara antiquata -Avicennia lanata, Anadara antiquata -Ceriops decandra, Gafrarium pectinatum -Avicennia lanata, Lutraria lutraria-Rhizophora mucronata). This pair of macrofauna with mangrove species shows a close relationship between the two. For future mangrove planting, it can be used as a benchmark by looking at macrofauna and mangrove pairs that are positively associated.

Mangrove Ecosystem Services in Mitigation for Mollusca Communities in Lembar Sheet District, West Lombok Regency

Mangroves have an important role in mitigation and a significant contribution to the wealth of macrofauna. The success of mangrove management has significantly affected the diversity of macrofauna which are associated biota. The research objectives were to investigate the composition of mangroves and mollusc communities, the ecological conditions of the waters, and evidence of mangrove ecosystem services in mitigation. The research data sources are faunal, ecological, and social data. The research method uses purposive sampling and data analysis using descriptive statistics. The results showed that 7 mangrove species were found in the Cemare mangrove area. Avicennia marina, Bruguiera gymnorriza, Ceriops tagal, Rhizophora apiculata, Rhizophora mucronata, Rhizophora stylosa, and Sonnetaria alba. The dominant mangroves were Rhizopora stylosa (201 ind/Ha) and Rhizopora apiculata (146 ind/Ha). Meanwhile, the highest abundance of mollusc species was obtained by Cerithidea cingulate (38.94%) and Nerita undata (29.20%) from the gastropod class, while from the Bivalvia class, Anadara grandis (36.07%) and Anadara granosa (19.67%) were found). The condition of the aquatic environment at the research site is still within the tolerance range required for the growth and development of mollusk species. Furthermore, the majority of respondents know or are aware that mangroves have an ecological function (habitat/habitat for animals), an economic function (a livelihood location), a physical mitigation function (abrasion resistance), a non-physical mitigation function (reducing environmental heat) Good category. These results indicate that efforts need to be made to increase mangrove revegetation, given its significant benefits in mitigation.

Chromosome-level genome assembly of the Pacific geoduck Panopea generosa reveals major inter- and intrachromosomal rearrangements and substantial expansion of the copine gene family.

The Pacific geoduck Panopea generosa (class Bivalvia, order Adapedonta, family Hiatellidae, genus Panopea) is the largest known burrowing bivalve with considerable commercial value. Pacific geoduck and other geoduck clams play important roles in maintaining ecosystem health for their filter feeding habit and coupling pelagic and benthic processes. Here, we report a high-quality chromosome-level genome assembly of P. generosa to characterize its phylogeny and molecular mechanisms of its life strategies. The assembled P. generosa genome consists of 19 chromosomes with a size of 1.47 Gb, a contig N50 length of 1.6 Mb, and a scaffold N50 length of 73.8 Mb. The BUSCO test of the genome assembly showed 93.0% completeness. Constructed chromosome synteny revealed many occurrences of inter- and intrachromosomal rearrangements between P. generosa and Sinonovacula constricta. Of the 35,034 predicted protein-coding genes, 30,700 (87.6%) could be functionally annotated in public databases, indicating the high quality of genome annotation. Comparison of gene copy numbers of gene families among P. generosa and 11 selected species identified 507 rapidly expanded P. generosa gene families that are functionally enriched in immune and gonad development and may be involved in its complex survival strategies. In particular, genes carrying the copine domains underwent additional duplications in P. generosa, which might be important for neuronal development and immune response. The availability of a fully annotated chromosome-level genome provides a valuable dataset for genetic breeding of P. generosa.

Utilization of marine taxa within an artisanal shellcraft sector of the Indo-Pacific region

Sustainable utilization of marine taxa is critical for maximizing social and economic goals of livelihood development within the Indo-Pacific. Yet, despite an increasing importance of shellcraft as a livelihood activity within the Indo-Pacific, information on the taxa utilized within shellcraft sectors remains scant. To address this knowledge gap, our study examined diversity, in terms of composition and quantities, of marine taxa utilized by artisan households and, collectively, within an artisanal shellcraft sector of Papua New Guinea. For each taxon, critical source habitats were identified, and the geographic scale of exploitation established. Critically, presented data revealed 73 taxa, representing at least 77 species, were utilized within the studied sector. Many of the taxa utilized had not previously been linked to shellcraft sectors, demonstrating that a broader composition of taxa is utilized than previously acknowledged. In terms of quantity, annual utilization within the sector was close to 500,000 individuals, the majority being mollusks of either class Gastropoda (83.6%), represented by 37 genera, or class Bivalvia (9.6%), represented by four genera. There was a strong bias towards a particular species, Chrysostoma paradoxum (78.5% of all individuals), as indicated by indices for the diversity utilized (H′ = 1.23; D = 0.38). However, substantial variation was evident in the diversity of taxa utilized among households (n = 36) engaged in shellcraft (H′ = 1.09 ± 0.71; D = 0.43 ± 0.27), with each household utilizing a unique composition of 19.1 ± 10.6 taxa. Source habitats for taxa ranged from pelagic to benthic intertidal and subtidal substrates, with the geographic scale of exploitation extending to 34 discrete locations up to 417 km away. The array of sector, household, and taxon-specific information presented provides a basis for supporting greater sustainability within shellcraft sectors across the Indo-Pacific, which is discussed within a context of informing community-based resource management, further developing marine aquaculture, and strengthening existing governance.

Molluscan Diversity Present in Tawarja River at Peth in Latur District of Maharashtra

Latur district is a part of Maharashtra's Marathwada region in the southern part, which is geographically located in the Deccan plateau between 17°52′ and 18°50′ North and 76°18′ and 79°12′ east. It is typically 631 meters (2,070 feet) above mean sea level on the Balaghat plateau. Manjara is the main river which flows on the Balaghat plateau along with its tributaries: Terna, Tawarja and Gharni. The other three tributaries of Manjara are Manyad, Teru and Lendi which flow on the northern plains. Tawarja originates near Murud in Latur taluka and joins the Manjara river at Shivani on the Latur-Ausa boundary. The study was necessary for evaluating the ecological state of water bodies with the help of freshwater molluscs with studies focusing on variety, distribution, and ecology. Two sampling sites were chosen along the Tawarja River in Peth Village for mollusk collection, and these locations were carefully organized from the river's source to its confluence point following various land use/cover patterns. Throughout the course of the research, a total of 13 taxa were noted from all sample sites. The molluscan community was represented by two classes, namely Bivalvia and Gastropoda, with three species belonging to the former and ten to the latter. Three species and one family—the Unionidae—belong to the class Bivalvia. Gastropoda class had three orders, including Mesogastropoda, three families, and seven species. The study's crucial conclusions, which demonstrated that gastropods outnumbered bivalves, were taken. These species can be utilized as bioindicators of pollution and ecosystem health. The findings of this study might contribute to better molluscan fauna management and conservation in the area.

ANALISIS TIMBAL (Pb) DAN KADMIUM (Cd) PADA KERANG BULUYANG DIPEROLEH DARI PASAR SEI SIKAMBING MEDAN SECARA KUALITATIF

Shellfish (Anadaraantiquata) is one type of shellfish that has the potential to be used as a food source in fulfilling the nutrition of the Indonesian people. Feather clams (Anadaraantiquata) belong to the class Bivalvia which are edible and have economic value. The purpose of this study was to determine the content of lead and cadmium in feather shells. Samples were taken from two fur shell traders at the Sei Sikambing market in Medan using a random sampling method with qualitative testing using disodium sulfide, potassium iodide, potassium chromate, potassium cyanide, and sodium hydroxide reagents, in accordance with work procedures. used in the Medan Regional Health Laboratory. The results showed that of the two samples tested, both samples did not contain lead (Pb) and cadmium (Cd).
 Keywords: Feather shells, lead (Pb), Cadmium (Cd), Qualitative.

Assessment of benthic macroinvertebrates as potential bioindicators of anthropogenic disturbance in southeast Bangladesh coast.

Many human activities can greatly influence and alter the health of aquatic ecosystems. In this regard, the quantitative analysis of macroinvertebrates and their relationships with ecological variables is an effective method in environmental monitoring programs. Here, we used the benthic macroinvertebrate community as bioindicators for assessing anthropogenic impacts on coastal waters in southeast Bangladesh. Sediment samples were collected seasonally from three different sites influenced either by mangrove forests, aquaculture activity or sewage input. The indicator value index (IndVal) analysis revealed 23 species of benthic macroinvertebrates as potential bioindicators namely Enigmonia aenigmatica, Mactra chinensis and Pharella javanica of the class Bivalvia; Tubifex tubifex of the class Clitellata; Lithopoma brevispina, Bullia vittata, Pomacea maculata and Umbonium vestiarium of the class Gastropoda; Gammarus roeselii of the class Malacostraca; and Amphicteis gunneri, Amphitrite ornata, Aricidea simplex, Cirratulus cirratus, Heterospio catalinensis, Hypereteone foliosa, Lopadorrhynchus henseni, Neanthes chingrighattensis, Micronephthys oligobranchia, Nephtys hombergii, Nereis jacksoni, Nereis zonata, Polyodontes maxillosus and Stygocapitella subterranean of the class Polychaeta. Their composition across three sites varied significantly (P<0.05) due to influence of environmental conditions as inferred from redundancy analysis. Polychaeta, Gastropoda and Malacostraca were susceptible to sewage input, while Bivalvia and Clitellata were susceptible to aquaculture effluent. The results of this baseline study suggest that the identified benthic macroinvertebrate species can potentially be used to monitor anthropogenic disturbances in the marine environment.

Mollusk Diversity in Percut Sei Tuan Silvofishery Ponds, North Sumatra, Indonesia

Highlight Research We found 16 species of mollusks with a total of 15 species from the gastropod class and 1 species from the Bivalvia class bivalves in the silvofishery ponds, recording a total of 369 individuals. The density of mollusks in July in pond I was 3.6 ind/m2, while it was 10.66 ind/m2 in pond II. The mollusk diversity index in October after rehabilitation was included in the high diversity category because the value of H' was 1.6 - 3.0. Pond I has a diversity index value of 1.89 and pond II 1.82. The value of C-organic concentration in both ponds ranged from 3.00% to 5.72%, which is the optimum level for mollusk growth. Abstract Silvofishery is a system that combines mangrove and fishery to protect mangrove ecosystems and restore their functions, one of which is as a habitat for macrozoobenthos. Investigate the mollusks and mangrove density. Mollusk sampling was carried out on sub-plots measuring 1 x 1 m² in the mangrove vegetation transect, and mangrove density was measured by counting the number of trees directly on all of the mangrove species at two silvofishery ponds. A total of 16 species of mollusks were found at the observation site, consisting of gastropods and bivalves. The density of mollusks in July was 20 ind/m2 in pond I, while it recorded 9 ind/m2 in pond II. In October, after pond II rehabilitation, the density was inversely proportional to July, and the highest density was found in pond I at 10 ind/m2, while pond II measured 9 ind/m2. After rehabilitation, the index value H’ decreased in pond I and pond II from 2.82 and 2.98 to 2.52 and 2.68, respectively. The mangrove density was 887 ind/ha in pond I and 686 ind/ha in pond II. The substrate in both ponds was clay. Nitrate concentration values ​​in the substrate in both ponds ranged from 0.27% to 0.29%, phosphate recorded a percentage of 0.07–0.09%, and C-organic ranged from 3.00% to 5.72%. The water's physicochemical parameters and the type and content of the substrate were still suitable for mollusk life.

MOLECULAR IDENTIFICATION TOOLS FOR BIVALVES: A REVIEW

The Bivalvia class constitute an important molluscan class that exert its effect on human society an important food component and sentinel organism indicating environmental contamination. Accurate species identification is a prerequisite for management of aquaculture, diversity studies and for human consumption. Presence of different species of bivalves on the global markets for human consumption has given rise to several commercial frauds based on species substitution. Reliable and rapid techniques are required to identify seafood species in different products and thus prevent wilful or unintentional fraudulence. This article reviews the molecular tools used by different researchers in the last two decades. By reviewing virtually all genetic markers used during the last two decades of bivalve molecular research, it is obvious that the best tools for bivalve molecular study are mitochondrial COI and nuclear ITS2.

Case study of the convergent evolution in the color patterns in the freshwater bivalves

The class Bivalvia (phylum Mollusca) is one of the most successful at survival groups of animals with diverse color patterns on their shells, and they are occasionally preserved in the fossil record as residual color patterns. However, the fossil record of the residual color patterns in freshwater bivalves could be traced only to the Miocene, greatly limiting color pattern evolution knowledge. We present the color patterns of the Cretaceous freshwater bivalves belonging to three extinct families of the order Trigoniida (hereinafter the Kitadani Freshwater Bivalves) from Japan, which is the oldest and the second fossil record of freshwater molluscan color patterns. The Kitadani Freshwater Bivalves consists of two types of color patterns: stripes along the growth lines and radial rays tapered toward the umbo, which resemble that of the colored bands of extant freshwater bivalves. This resemblance of the color patterns between the Kitadani Freshwater Bivalves and the extant species indicates that the color patterns of the freshwater bivalves represent the convergent evolution between Trigoniida and Unionida. To explain this convergent evolution, we advocate three conceivable factors: the phylogenetic constraints, monotonous habitats typical of freshwater ecosystems, and the predation pressure by visual predators in freshwater sediments.

Macrobenthic community status at coastal cage aquaculture area in Xuan Dai bay, Phu Yen province, Vietnam

Lobster cage culture started around 1990 in Xuan Dai bay and grew fast in recent years, contributing significantly to the socio-economic development of the region. But the impact on the ecological environment of cage culture operation also needs to consider. This paper points out the status of the macrobenthic community, studied at two stations inside the cage culture area (X1, X2) and one reference station (Xr) in the non-cage culture area. A total of 90 samples with 5 replicate samples per station were collected in six surveys during the dry and rainy seasons from June 2019 to May 2020. These samples were classified and recorded into 80 taxa belonging to 49 families and 5 classes. The class Polychaetes had the most diverse species composition with 53 taxa (66% of the total number of taxa). The crustacean group had 14 taxa (18%) belonging to 13 families; Molluscs had 9 taxa (11%) belonging to 6 families of class Bivalvia. The echinoderms had 4 taxa (5%). Capitella capitata, a species known as an indicator of organic pollution, was recorded in both stations of the culture area but was not present at the reference station. Furthermore, some dominant species presented in the culture stations such as Cossura longocirrata (contributed 43.52% in station X1) and Ceratonereis sp. (contributed 27.57% in station X2). These species are considered opportunistic species that can adapt to disturbed environmental conditions. Significantly, the species of echinoderms group were only recorded in the reference station. The species composition was only about 24% similar to those at the cage culture stations. The species richness index (D) values ranged from 1.50 (X2.6) to 6.82 (Xr.3). The diversity index (H′) varied from 0.88 (X2.4) to 2.98 (Xr.3). The evenness index (J) had the lowest average value at station X2 (J = 0.59 ± 0.20) and the highest value at the reference station Xr (J = 0.78 ± 0.03). The indices D, H′ and J of the macrobenthic community at the reference stations have higher average values compared to those estimated at cage culture stations. These results proved cage culture activities have gradually impacted the benthic fauna, reduced biodiversity, and encouraged the appearance of opportunistic species. Thus, further studies on the macrobenthic community dynamic with ecological criteria are necessary to establish a set of biological indicators to monitor the environmental quality of the coastal aquaculture area.

Morphological characteristics and genetic diversity of the Anadara antiquata distribution in Central Vietnam

Anadara antiquata belongs to the Mollusca phylum, class Bivalvia, distributed in the coastal areas of Vietnam, with high nutritional and economic value. This study focused on the morphological characteristics and genetic diversity of A. antiquata in six regions of central Vietnam (Da Nang, Quang Nam, Phu Yen, Nha Trang, Binh Thuan and Thanh Hoa). The analysis of morphology of A. antiquata had the following results: shell width (SW: 41.45 mm), shell length (SL: 22.54 mm), right shell height (HRV: 29.27 mm), height left sheath (Coach: 28.49 mm), ligament length (LL: 25.74 mm), right trochanteric cavity depth (UHR: 7.90 mm), left trochanteric space depth (UHL: 8, 33 mm), right case symmetry (SRV: 8.58 mm) and left case symmetry (SLV: 8.41 mm). The mean shell volume (SV) and shell cavity volume (DSWT) were 4.45 ml and 11.11 ml, respectively. The average dry peel weight was 11.17 g. Genetic diversity showed that the 8 random primers used to analyze DNA polymorphisms of 41 A. antiquata had 87 amplified polymorphic DNA bands.

Diversity and Spatial Distribution of Freshwater Macro-Invertebrates in Poba Reserve Forest of Assam, India

Seasonal investigation of aquatic macro-invertebrates in the aquatic bodies of Poba reserve forest (PRF) of Assam, India revealed altogether 55 species belonging to 29 families, 13 orders and five classes from three phyla viz., Arthropoda, Annelida and Mollusca. Class Insecta was found to be the dominant taxa represented by six orders and 17 families that comprised 35 species (63.63% of the total species richness). Gastropoda was the second dominant class represented by the families viz., Viviparidae, Ampullaridae, Pachychilidae, Thiaridae and Planorbidae, contributing with 17.24 % to the total 29 families. With two families (6.89%) class Bivalvia was represented by Unionidae and Cyrenidae families. On the contrary, the class Clitellata was comprised of only a single family and represented by the annelid Hirudinaria manillensis. Dytiscidae and Unionidae were found to be the dominant families comprised of seven species each, which contributed 12.72% to the total recorded species richness in the PRF. A spatial distribution pattern of the aquatic macro-invertebrate assemblages was observed during the study period. The highest abundance of macro-invertebrate species was recorded during the post-monsoon season (N=6148) proceeded by reduced abundance during the winter season (N=5101), pre-monsoon (N=4807) and monsoon season (N=4136) respectively. The present study is the first account of the freshwater macro-invertebrates diversity in the PRF which provides a piece of baseline information on the copiousness of different aquatic macro-invertebrate species of the reserve forest.

Evidence of multiple genome duplication events in Mytilus evolution

BackgroundMolluscs remain one significantly under-represented taxa amongst available genomic resources, despite being the second-largest animal phylum and the recent advances in genomes sequencing technologies and genome assembly techniques. With the present work, we want to contribute to the growing efforts by filling this gap, presenting a new high-quality reference genome for Mytilus edulis and investigating the evolutionary history within the Mytilidae family, in relation to other species in the class Bivalvia.ResultsHere we present, for the first time, the discovery of multiple whole genome duplication events in the Mytilidae family and, more generally, in the class Bivalvia. In addition, the calculation of evolution rates for three species of the Mytilinae subfamily sheds new light onto the taxa evolution and highlights key orthologs of interest for the study of Mytilus species divergences.ConclusionsThe reference genome presented here will enable the correct identification of molecular markers for evolutionary, population genetics, and conservation studies. Mytilidae have the capability to become a model shellfish for climate change adaptation using genome-enabled systems biology and multi-disciplinary studies of interactions between abiotic stressors, pathogen attacks, and aquaculture practises.

KONDISI PERAIRAN DAN PENDUGAAN IKAN DI TELUK CILETUH, SUKABUMI JAWA BARAT BERDASARKAN PROFIL NUTRIEN DAN MAKROZOOBENTOS

Ciletuh Bay is a Global Geopark area since 2018 by UNCESCO. Ciletuh Bay is located in the south of Java Island which is directly facing the Indian Ocean, so Ciletuh Bays has unique water characteristics. This research aims to determine the condition of the waters of Ciletuh Bay in terms of physical, chemical, and biological parameters. This research was conducted in the dry season in June 2019 and the rainy season in February 2021. The parameters observed in this study were temperature, salinity, pH, dissolved oxygen, brightness, depth, ammpnia, nitrite, nitrate, phosphate, chlorophyll-a, sediment substrate, and macrozoobenthos. The results showed that the concentration of ammonia, nitrite, and chlorophyll-a had the highest values in the rainy season with values for each parameter of 0,028 mg/L; 1,663 mg/L; dan 2,82 mg/L. meanwhile, the highest concentration of nitrate and phosphate were found in the dry season with each having a value of 0,717 mg/L; dan 0,09 mg/L. The sediment substrate during both seasons is dominated by sand. Macrozoobenthos during the rainy season is dominated by the Gastropod class, while during the dry season it is dominated by the Bivalvia class.

Spatial and temporal variation in the diversity of malacofauna from Aripal stream of Kashmir Himalaya, India

This paper presents the spatial and temporal variation in the diversity of malacofauna in relation to the water chemistry of the Aripal stream of Kashmir Himalaya. A total of 12 species were reported which belong to four families, Lymnaeidae, Physidae, Planorbidae, and Bithyniidae from class Gastropoda, and two families, Cyrenidae and Pisidiidae from class Bivalvia. The family Planorbidae contributed 34% to the total annual molluscan population followed by Lymnaeidae (28%) and Bithyniidae (18%). During the collection, Gyraulus sp., Planorbis sp., and Bithynia tentaculata were prevalent at all sites, with predominance of Bithynia tentaculata. Species richness and abundance were observed maximum at site A3 (down-stream) and minimum at site A1 (up-stream) while in the case of temporal variation, species richness and abundance were maximum in summer and minimum in winter. Shannon-Wiener index, Simpson index, Margalef index, and Pielou evenness index were used to calculate the diversity, dominance, richness, and evenness of molluscan species, respectively. Physico-chemical parameters revealed a non-significant spatial variation (P &gt;0.05) except pH, total hardness, and alkalinity while a significant temporal variation (P &lt;0.05) was observed in the physico-chemical parameters except dissolved oxygen. A significant positive correlation was seen between the molluscan species and total hardness. In the present study, the stone mining, channel morphology of stream, habitat heterogeneity, and physico-chemical parameters were also found to promote the spatial and temporal diversity of malacofauna.

The biodiversity richness of Mollusk species in Lanaga waters, Meureubo Subdistrict, Aceh Barat Regency, Aceh Province

Mollusca are soft-bodied animals that are generally protected by shells, and have a variety of species richness in habitat, especially in Lanaga Waters, Mereubo Subdistrict, Aceh Barat Regency and need to be studied through research. The research objectives were (1) to assess the number of species of each class, and (2) to analyse the level of species richness of each class of molluscs, which are found in Lanaga Waters, Meureubo Sub-district, Aceh Barat district, Aceh Province. The research was carried out from January to March 2021, in Lanaga Waters. The research area was divided into three locations, each location was divided into five stations, and each station was assigned five sampling plots. Data were taken by using the purposive sampling technique. Data analysis of species richness level was analysed by richness formula, and analysis of data about the number of each species in each class was carried out descriptively. The results showed that (1) the species of Molluscs belonging to the Gastropod class were 9 species with a richness index, the Bivalvia class contained 2 species with a species richness index of 0.13 to 0.90 indicating that the level of species richness was low to high, in the Lanaga Waters area. Mereubo Subdistrict, Aceh Barat Regency, Aceh Province.