Distribution Of Molluscs Research Articles

Repeatable patterns in the distribution of freshwater biodiversity indicators across contrasting landscapes

Abstract Context Freshwater biodiversity is declining at unparalleled rates, but fundamental questions remain over how it is distributed at the spatial scales most relevant for conservation management. Objectives Here, we test the hypothesis that freshwater biodiversity is distributed across standing waterbody types in a pattern that is reproducible across disparate biota and contrasting landscapes, such that conservation efforts can be aligned across landscapes and taxa. Methods We analysed the richness, composition and distribution of macrophytes, molluscs, beetles and odonates from 199 standing waterbodies (lakes, ponds, ditches and canals) nested within UK landscapes with contrasting dominant land use (agricultural, upland and suburban). Results We found a common pattern in the distribution of our biodiversity indicators across waterbody types in all landscapes that was largely repeated across biota; lakes consistently had the highest or equal alpha diversity and supported a greater proportion of the sampled species pool in each landscape (mean = 86%) in comparison to ponds (74%). Landscape-specific waterbody types (ditches and canals) also contributed significantly to the regional species pool (69 and 33% respectively). Each waterbody type contributed uniquely to landscape biodiversity and usually species of conservation concern, rather than simply supporting a subset of ubiquitous species found in lakes. Conclusions Landscape-wide management strategies that encompass multiple habitats and biota should prove advantageous and generalisable. However, our study landscapes suggest that long-term biodiversity conservation should also recognise lakes as a priority for nature recovery, both to minimise further losses and to maintain the largest reservoir of biodiversity.

EFFECT OF SANGZOR RIVER WATER TEMPERATURE, CLARITY AND FLOW RATE ON BIVALVE MOLLUSCS

The article provides information on the factor, clarity and flow rate of the Sangzor River, which influence the distribution of molluscs, in which the temperature, clarity and flow rate of the Sangzor River vary in different parts of the river.

An updated checklist of non-marine molluscs of the western Himalaya

This paper presents the first comprehensive checklist of the non-marine molluscs from the western Himalaya, a region of high biodiversity and endemism. Based on faunistic surveys during 2019-2023 and published records, the paper reports 242 species belonging to 101 genera and 45 families of gastropods and bivalves, of which 168 species are endemic to the region. The paper also provides new distribution records and taxonomic notes for some species. Among the notable findings are the first records of Limax mayae, Oxyloma sp., Odhneripisidium kuiperi, Thiara aspera from India, and Bensonies jamuensis, Euaustenia cassida, Stagnicola sp. from the western Himalaya. The paper presents some species with substitutional illustrations and literature from the region for the past two centuries. Additionally, the paper also discusses the threats that non-marine molluscs face in the western Himalaya and suggests some conservation measures to protect them. The authors hope this paper will serve as a baseline for future studies on the diversity, distribution, ecology, and conservation of non-marine molluscs in the western Himalaya.

Distribution of Commercially Important Edible Mollusc (Bivalvia and Gastropoda) from Six Districts of Terengganu, Malaysia

Terengganu has a large coastal and wetland area where it provides habitat for edible mollusc. The edible molluscs are one of the most important sources of animal protein for the local communities. The distribution of edible molluscs was studied in six districts of the Terengganu coastal waters between August 2020 and March 2022. In each district, samples were purchased from the wet market, fishing villages and roadside outlets every four months interval. A total of 1,043 individuals was observed and 23 species of edible molluscs were recorded from six districts of Terengganu representing 11 families. Bivalves were found to be dominated by 14 species from seven families. The family Cyrenidae (bivalve) was widespread in five districts where Geloina expansa, was recorded in almost all districts. Meanwhile, for gastropods, nine species from four families were found where Ellobiidae (gastropod) was dominant and the most common gastropod species was Faunus ater, which was found in four locations in Terengganu. These species have great commercial value in Terengganu districts as they are sought extensively as food by the locals and also represent one of their sources of financial survival, especially for those living near to coastal areas. This baseline study could serve as a future indicator for the sustainable management of fisheries resources and for further ecological studies.

Spatial Distribution, Size and Age Composition of Population of <i>Mya japonica</i> Jay, 1857 (Bivalvia: Myidae) in Peter the Great Bay, Sea of Japan

In July–August 2022, the spatial distribution and the composition of local aggregations of the bivalve mollusc Mya japonica Jay, 1857 in the Vostok Bay (Peter the Great Bay of the Sea of Japan) were studied. M. japonica occurred almost throughout the entire bay in a wide range of depths from 0 to 22 m at water temperatures from –1.9 to 25°С and salinity from 0 to 34‰. M. japonica was the most abundant in the shallow areas of the bays, closed from the direct wave impact, where, at a depth of up to 4–5 m, the density of the mollusc reached 27 ind./m2, and the biomass was almost 4 kg/m2, which averaged 56% of the total macrozoobenthos biomass. With increasing depth and moving from the dead-end of the bay to the open sea, the abundance of M. japo-nica decreased by one or two orders of magnitude. Local settlements differed significantly in size and age composition, size-frequency distribution of molluscs, indicating the nature of the replenishment of the benthic population with juveniles, as well as the proportion of commercial size individuals, which ranged from 37 to 98%. The reasons for the revealed features of the distribution and structure of the population of M. japonica are discussed.

Abundance, Distribution, and Diversity of Freshwater Snail and Prevalences of Their Infection by Cercaria of Fasciola gigantica and Schistosoma spp at Mayo-Vreck River, Far North Region of Cameroon.

Malacological and parasitological studies were conducted from April 2020 to March 2021 to determine the abundance and distribution of molluscs and cercariae of Schistosoma spp and Fasciola gigantica. Collected molluscs are exposed to strong light to induce cercarial release. Mollusc densities were higher at station 1 (Gamak) than in station 8 (Patakai), with Bellamya unicolor and Biomphalaria pfeifferi more abundant and Bulinus truncatus, B. tropicus, and B. globosus less abundant. The overall prevalence of cercariae (19.87%) is higher in station 3 (Yaye orchard), station 9 (Gougni), station 4 (Madiogo), station 5 (Madiogo pasture), and station 6 (Ziam 3). It varies significantly between 15.76% in station 8 and 25.77% in station 3, between 8.48% in B. truncatus and 25.53% in B. globosus, and between 19.27% for cercariae of Schistosoma spp and 21.60% for those of F. gigantica. Cercarial emissions in L. natalensis and B. pfeifferi were higher in hot and cold dry seasons; on the other hand, cercarial emissions in B. globosus were higher in hot dry seasons (31.48%) and rainy seasons (23.38%). Emissions of cercariae from S. haematobium are related to areas of human activity and defecation, while those of F. gigantica in L. natalensis, Schistosoma haematobium in B. tropicus, and S. mansoni in B. pfeifferi are related to grazing areas. Mayo-Vreck is a site that favors the endemicity of fascioliasis and human schistosomiasis.

Species composition and distribution of mollusca on dead coral from Central to North Vietnam

A study on Mollusks’ species composition and distribution on dead coral from Quang Ngai to Cat Ba was conducted during the field survey between Vietnam and Russia on the AKADEMIC OPARIN RC vessel in 2021 at 39 reef stations in 14 study areas. By comparative morphology method, the authors have identified 135 taxa of Mollusca belonging to 48 families, 4 classes on coral reefs. The species composition of Mollusca was slightly different between study areas.

Factors Influencing the Distribution of Freshwater Mollusks in the Lakes of the Pyrenees: Implications in a Shifting Climate Scenario

Climate warming is expected to drive an upward altitudinal shift of species distributions in mountain areas. In this study, we consider how environmental variables constrain the distribution of freshwater mollusks across elevations based on an extensive survey of the entire Pyrenean range. Results show that several altitude-related variables are significantly relevant for the distribution of all mollusks (i.e., temperature, sediment organic content). Others respond more precisely to some variables: fine substrate proportion increases the probability of finding Pisidium sensu lato (mostly Euglesa species), and the latter, the macrophyte presence, and Ampullaceana balthica. Despite the low acid-neutralizing capacity in many of the lakes, only the distribution of A. balthica was significantly constrained by this factor, independent from elevation. The results confirm a likely altitudinal expansion of the distributions of all species, particularly toward lakes with a summer surface temperature increasing above 12 °C. The pace of change is expected to differ among species according to different nonlinear thresholds in thermal response, which temperature value increases from Pisidium s.l. to Ampullaceana to Ancylus, and the taxon-specific sensitivity to substrates and chemical conditions.

DIVERSITY AND IMPACT OF SEASONAL VARIATION IN THE DISTRIBUTION OF MOLLUSCS IN MANAPADU COASTAL AREA, THOOTHUKUDI DISTRICT, TAMIL NADU, INDIA

Molluscs are economically and ecologically important components of aquatic ecosystems. In addition to supporting valuable aquaculture and wild-harvest industries, their populations determine the structure of benthic communities, cycling nutrients and they serve as prey resources for higher trophic levels. This study aims at identifying the diversity of Molluscs in the coastal area of Manapadu, Thoothukudi District, Tamil Nadu. The result of the study shows that a total of 61 species of molluscs belonging to 35 families were identified. Maximum numbers of species were identified during the post-monsoon season. Minimum species were identified during the summer season. ANOVA was carried out to test the level of significance. Significant results were observed only during the monsoon season. Biodiversity indices were calculated in which maximum species diversity of Shannon(H) Weiner index was noted as 4.107ng during the monsoon season, and minimum species diversity was recorded as 4.037 ng during the post-monsoon season. Alpha index and Margalf’s index were also used in the study which showed varied diversity throughout different seasons. The study shows that molluscan species fluctuated seasonally throughout the year. Suggestions to update the checklist and distribution of Molluscs from the Manapadu region located on the southeast coast of India were presented in this study.

Diversity and distribution of molluscs (Gastropoda and Bivalvia) in the seagrass beds at Pulau Gazumbo, Penang, Malaysia

Diversity and distribution of molluscs (Gastropoda and Bivalvia) in the seagrass beds at Pulau Gazumbo, Penang, Malaysia

Identification of Mollusc Remains (Bivalve and Gastropod) from Archaeological Sites in Semporna, Sabah.

This paper discusses the identification of mollusc (bivalve and gastropod) remains from three archaeological sites in Semporna, Sabah, namely Bukit Tengkorak, Melanta Tutup and Bukit Kamiri, dated to the prehistoric period, from 3,000 to 800 years ago. Samples of mollusc remains used in this study were obtained from a series of archaeological excavations conducted at these three sites by the Centre for Global Archaeological Research, Universiti Sains Malaysia (CGAR, USM), Penang in collaboration with the Sabah Museum Department (SMD) from 1994 to 2007. In total, 90 taxa of molluscan species, of which 30 are bivalves and 60 are gastropods, had been identified. Out of 90, there were 55 taxa identified to the species level, of which 18 are bivalves and 37 are gastropods. They consisted mainly of marine species with small numbers of freshwater, brackish and terrestrial species. This study had provided new data and insights into the distribution and exploitation of molluscs by ancient human societies in different environments in Semporna, which will be useful not only for malacological research in the tropics but also for future biological and environmental studies in Sabah, Malaysia as well as for the Southeast Asian and Pacific regions.

Diversity and distribution of bivalve molluscs in the Central Cantabrian Sea and the Avilés Canyons System (Bay of Biscay)

Bivalve molluscs is one of the dominant benthic groups in soft-sediment communities off the Atlantic Ocean, including the European margin and the Bay of Biscay. The current knowledge of deep-sea Euro-Atlantic bivalves and their distribution is still far from comprehensive and has been the scope of several recent publications. We examined the collected bivalve samples from two oceanographic campaigns (COCACE and BIOCANT) carried out in the central Bay of Biscay, including the Avilés Canyons System (ACS), a Site of Community Importance within the Natura 2000 Network. Bivalve specimens were collected from the continental shelf, slope and bathyal zones, ranging in deep from 25 to 4700 m. This is the first study focused on bivalve diversity from the Cantabrian Sea that covers such a wide bathymetric range. Eighty-four live taxa in 36 families were identified; Cetomya neaeroides is reported for the first time in the area. We provide photographs showing the shell diagnostic features of all recorded species. The conducted Multivariate Analysis showed three species assemblages: i) samples from shallow waters (continental shelf); ii) intermediate depths (shelf and upper slope) and iii) deep water (slope and abyssal plain). Depth was the main structuring factor that influenced the distribution of the recorded species and the higher species richness was found on the continental shelf. The feeding strategy and the substrate preference appeared as not significant factors in the zonation patterns of the studied bivalves.

MULTIVARIATE ANALYSIS SHOWING IMPACT OF DIFFERENT ENVIRONMENTAL FACTORS ON SPECIES RICHNESS AND SPECIES DENSITY OF FRESHWATER MOLLUSC COMMUNITIES INHABITING WATERS OF NORTH-WEST HIMALAYAS

Freshwater molluscs face extreme threat due to anthropogenic stress which is reflected in their changing population structure over time. The extent of this phenomenon needs to be monitored and proper management of freshwater ecosystem should be done. In the present communication, an approach was undertaken to study the effect of ten different physical and chemical factors affecting mollusc density and mollusc richness in both lentic and lotic water bodies of North-West Himalayas. A total of 10 species of gastropods and 3 species of bivalves were recorded. Bivalves remained absent from both lentic bodies while gastropods dominated in both lotic waters in terms of taxa richness. On subjecting physical and chemical parameters to a multivariate analysis, 7 out of 10 factors were found significant after univariate Analysis of Variance (p<0.05). Principal component analysis showed that all the study stations varied in terms of physical and chemical conditions in different seasons. Canonical correspondence analysis revealed that dissolved oxygen, depth, alkalinity, Calcium ions and Chloride ions were the variables that significantly associated with the distribution of molluscs. The regression analysis revealed that the concentration of chloride ions was the common factor that was negatively related to both taxa richness and taxa density.

Distribution of soft-bottom benthic molluscs in the Gulf of Oran (Western Algeria)

A total of 46 samples were taken in the softbottom of the Gulf of Oran, in order to study the nature of the sediments and the spatial distribution of the mollusc communities. As a result of sampling in the study area, at depth range (30 m -106 m), a total of 29 species were identified, included in two classes: Gastropoda and Bivalvia. The use of multi-variate statistical analyzes, as well as particle size analysis, made it possible to identify the main mollusc communities. Six mollusc communities were defined from faunistic and sedimentologic affinities. The malacological fauna of the Gulf of Oran is dominated by Saccella commutata (33.33%), Limatula subauriculata (20.83%) and Nucula sulcata (20.83%). The main ecological stocks are mixicole and coastal detritus species. The malacofauna of the Gulf of Oran is scarce and less diversified due to the nature of the soft bottoms (sand and gravel) and the absence of terrigenous inputs.

The distribution of offshore benthic molluscs provides new insight into South Africa's marine biogeography

South African marine biogeography has received a great deal of attention in the past. However, offshore biogeographic breaks are based on abiotic variables or specialist opinion rather than data-driven approaches. Here we investigate biogeographic breaks based on the distribution of offshore marine benthic molluscs collected during the Natal Museum Dredging Programme (1981–1997) along the coast of South Africa, between the South East Atlantic and South West Indian Oceans. Spatially constrained (depth, latitude and longitude) cluster analyses were applied to three resemblance measures; the Jaccard coefficient, popular in biogeographic studies, and gamma+ and theta+ coefficients, where taxonomic relatedness is considered when comparing sites. We used these resemblances to 1) find the most consistent biogeographic breaks and 2) compare the results of different measures to better understand the patterns and possible processes involved in the biogeographical classification. Although there were differences in the overall results from the three resemblance measures, they produced comparable findings at depths shallower than 80 m. Our data-driven approach indicated that the biogeographic break between the warm-temperate and sub-tropical assemblages was 140 km north of the current inshore break. The break between the sub-tropical and tropical mollusc assemblages agreed more closely with the present Ecoregions. Compared to Jaccard, where relatedness is not considered, gamma+ and theta+ results revealed a more substantial depth effect, and samples collected in the same depth range were more closely related and shared a more recent evolutionary history than geographically close samples from different depths. Furthermore, assemblages found deeper than ∼80 m demonstrated greater diversity in terms of relatedness, an essential consideration in marine spatial planning and consequent designation of protected areas. This study reveals the importance of including in-situ data and interspecies relationships in future marine spatial planning to ensure that these evolutionary rich animal communities are considered adequately.

Влияние абиотических факторов на распространенность и плотность видов семейств Unionidae, Pisididae, Euglesidae и Corbiculidae в высокогорных районах прибрежной зоны Кашкадарьи

As a result of the study, it has been identified that the water temperature in the Kashkadarya River is 18–24 °C, the water clarity is 0.51–0.62 m and the water flow rate is 0.72–0.84 m/sec. The species of bivalve mollusks Sinanodonta gibba, S. orbicularis, S. puerorum, Colletopterum cyreum sogdianum, Corbicula cor, C. fluminalis, C. purpurea, Corbiculina tibetensis, C. ferghanensis are widespread in the region. The abiotic factors discussed in the paper play an important role in the distribution of mollusks. There are 13 species of bivalve mollusks in the mountainous region, which is the head part of the river, 9 species in the middle part of the hill region of the river and 6 species in the lower desert region.

Распространение раковинных брюхоногих моллюсков в открытых частях Баренцева моря: предварительный анализ

Species composition and distribution of shell-bearing gastropods in the Barents Sea has been described only for coastal regions. We used material from 247 stations (530 samples) remoted from the coast. In some cases, the distribution of mollusks depended on the type of substrate, and in others, only geographic location was revealed. The latter is probably due to hydrological factors or the presence of historically formed faunal complexes. The use of different approaches to the removal of uninformative samples during analysis gives similar results.

Diversity and distribution of freshwater molluscan fauna in reservoirs and headwater streams of the Kala Oya river basin in Sri Lanka

In this study, the variation of aquatic molluscan diversity concerning seasonal water level fluctuations (WLF) and sediment texture was investigated in some perennial irrigation reservoirs and the associated head headwater streams in the Kala Oya river basin in Sri Lanka. Altogether 11,752 molluscan specimens belonging to 10 gastropod taxa (96.6%) and 2 bivalve taxa (3.4%) were identified. Of these, 11,282 specimens (96.0%) were from reservoir sampling sites and the remainder 470 (4.0%) was from the associated headwater streams. Of the gastropods, the individuals of the genus Melanoides showed the highest distribution index (DI) of 0.75 followed by Bellamya (DI = 0.63) and Thiara (DI = 0.60). The DI of the gastropod molluscs showed a significant positive relationship with their shell size (p < 0.05). Although molluscan diversity and taxa richness were comparatively lower in headwater streams than in reservoir sampling sites, Viviparidae (Bellamya; 0.06±0.03), Bithyniidae (Bithynia; 0.21±0.07) and Thiaridae (Thiara; 4.8±1.9 and Melanoides; 1.1±0.8) showed higher relative abundance (expressed as individuals per dm3) in the headwater streams. The reservoir water level fluctuation showed a significant negative relationship with molluscan taxa richness (p < 0.05), but not with the Shannon-Weaver diversity index (p = 0.073). The distribution of molluscs was also found to be related to the sediment texture where the most abundant gastropod genera Bellamia, Bithynia, and Thiara were widely distributed in sandy substrates in reservoirs and associated streams in the Kala Oya river basin.

A systematic review of flukes (Trematoda) of domestic goose (Anser anser dom.)

Trematodes are one of the most numerous and widespread groups of parasitic invertebrates among helminths, characterized by a complex life cycle. As the final host, digenetic flukes parasitize vertebrates, including domestic waterfowl. Infection of hosts with parasitic digenetic worms causes huge economic damage to poultry. But trematode fauna of domestic geese are presented mainly only for individual regions. Despite the fact that there is already a systematic review of tapeworms and acanthocephala of domestic birds – geese and ducks, there are, unfortunately, no review articles on the taxonomy of digenetic flukes for geese (Anser anser dom.). Taking into account the relevance of the topic, based on our own and extensive literature data, we set the task to determine the general species composition of digenetic flukes (Trematoda), parasitizing in domestic geese which have been recorded in the world until 2020. Each Trematoda species is provided with the following data: scientific name, authority and year, first, second intermediate, auxiliary and final hosts, site in the host body, collecting localities and geographic distribution, and literature sources. Currently it is established that there are 149 species of helminths parasitising domestic geese. The taxonomic composition of the class Trematoda registered in domestic geese consists of 2 classes, 14 families, 30 genera and 65 species. Of all the species of trematodes parasitizing in domestic geese, 44 species have been recorded in Europe, 26 species in Asia, 6 species in North America, 1 species in South America, 1 species in Africa and 2 species in Oceania. Three species are registered in domestic geese (Echinoparyphium recurvatum, Echinostoma revolutum, Prosthogonimus ovatus) are cosmopolitan parasites. The biggest species diversity is characterized by the families Echinostomatidae (17 species) and Notocotylidae (12 species). There are 11 species of digenetic flukes recorded in domestic geese Cyclocoelum mutabile, Echinostoma grande, E. paraulum, E. revolutum, E. robustum, Hypoderaeum conoideum, Paryphostomum novum, P. pentalobum, Catatropis verrucosa, Notocotylus attenuatus, N. parviovatus) on the territory of Azerbaijan. Four of them (Echinostoma revolutum, Hypoderaeum conoideum, Paryphostomum novum, Notocotylus attenuatus) were also noted in the course of our helminthological studies. The trematode Cyclocoelum mutabile was recorded in domestic ducks only in Azerbaijan. Most species of trematodes were found in the north-eastern part (total 9 species) and southern part (total 5 species) of Azerbaijan. This is due to the widespread distribution of molluscs – intermediate hosts of digenetic flukes, in these regions. Eighteen species of digenetic flukes parasitize both birds and mammals (Rodentia, Carnivora, Lagomorpha, Artiodactyla). And eleven species of trematodes are of medical importance, registered in humans.

MIOCENE NERITIC BENTHIC FORAMINIFERAL COMMUNITY DYNAMICS, CALVERT CLIFFS, MARYLAND, USA: SPECIES POOL, PATTERNS AND PROCESSES

ABSTRACTThe presence/absence and abundance of benthic foraminifera in successive discrete beds (Shattuck “zones”) of the Miocene Calvert and Choptank formations, exposed at the Calvert Cliffs, Maryland, USA, allows for investigation of community dynamics over space and time. The stratigraphic distribution of benthic foraminifera is documented and interpreted in the context of sea-level change, sequence stratigraphy, and the previously published distribution of mollusks. Neritic benthic foraminiferal communities of four sea-level cycles over ∼4 million years of the middle Miocene, encompassing the Miocene Climatic Optimum and the succeeding middle Miocene Climate Transition, are dominated by the same abundant species. They differ in the varying abundance of common species that occur throughout most of the studied section and in the different rare species that appear and disappear. Transgressive systems tracts (TSTs) have higher species diversity than highstand systems tracts (HSTs) but much lower density of specimens. In contrast to some previous research, all beds in the studied section are interpreted as being from the inner part of a broad, low gradient shelf and were deposited at water depths of less than ∼50 m. It is suggested that species are recruited from a regional species pool of propagules throughout the duration of TSTs. Recruitment is curtailed during highstands leading to lower diversity in the HSTs.