Molluscan Fauna Research Articles

Paleoenvironmental Evolution and Sea Level Change in Saronikos Gulf (Aegean Sea, Greece): Evidence from the Piraeus Coastal Plain and Elefsis Bay Sedimentary Records

Thorough faunal (benthic foraminifera, ostracods, molluscs) and palynomorph analyses as well as magnetic susceptibility measurements performed on the Piraeus coastal plain sedimentary sequences have shed light on the paleoenvironmental evolution of the area since ca. 9000 cal BP. Benthic and palynomorph assemblages along with magnetic susceptibility suggest a typical lagoonal environment with significant freshwater inputs at the eastern part of the plain after 8700 cal BP. Between 7500 and 5400 cal BP, microfaunal assemblages, mollusc fauna and magnetic susceptibility suggest a shallow marine paleoenvironment, with Piraeus forming a tied island in the center of the bay. Since ca. 4800 cal BP a closed oligohaline lagoon is evidenced in the western part of the Piraeus plain further developed to a marsh after 2800 cal BP, while a coastal environment associated with the fluvio-deltaic system of Kifissos and Korydallos Rivers is continually developing to the west. Signs of cultivation and grazing activities in the area are evidenced since the Early Bronze Age, culminating during the Classical Period. A comparison with a well-dated marine record, recovered from the nearby shallow Elefsis Bay, provides a reasonable estimation of ~5 mm/yr for the absolute sea level rise rate in the inner Saronikos Gulf during the Mid-Holocene.

Short-Term Assessment on the Species Composition of Marine Molluscan Fauna in Dharmadam Island, Kannur District, Kerala

Short-Term Assessment on the Species Composition of Marine Molluscan Fauna in Dharmadam Island, Kannur District, Kerala

Freshwater molluscs of the Zrmanja and Krupa Rivers (Croatia) – the role of these rivers as a refuge of threatened and endemic species

The Balkan region is inhabited by hundreds of endemic species of freshwater molluscs but the information on their distribution, as well as that on the distribution of more common and widespread species, is still insufficient; most areas have no complete inventories of their mollusc faunas. The Zrmanja is one of the largest rivers in the Adriatic part of Croatia. Its freshwater molluscs were studied in the last decade, resulting in a substantial body of distributional data. The main objective of this study was to summarise and analyse the recent distributional information on its freshwater molluscs, with special reference to endemic or threatened species. In total 33 freshwater mollusc species were found in the Zrmanja River and its tributaries at 73 sites. The middle section of the Zrmanja River and its largest tributary, the Krupa River, were the richest studied parts. Dalmatinella fluviatilis Radoman, Tanousia zrmanjae (Brusina) and Islamia zermanica Radoman, endemic to the Zrmanja catchment area, were found in the middle and lower sections of the river. Their occurrence is scattered and limited in area; T. zrmanjae is probably on the verge of extinction. The occurrence of the endemic Belgrandiella kusceri (Wagner), Hadziella sketi Bole and Kerkia sp. in springs or underground waters and an abundant population of Unio elongatulus C. Pfeiffer in the Zrmanja and Krupa Rivers is also noteworthy. The area can be regarded as an important part of the Balkan region, one of world’s hotspots of global biodiversity. Although it is protected, there are still anthropogenic factors that are negatively affecting or may affect the mollusc assemblages.

First record of Tomostele musaecola (Morelet, 1860) (Gastropoda: Eupulmonata: Streptaxidae) from the Dominican Republic and its current distribution in the Western Hemisphere

The presence of alien mollusc species in an ecosystem has a negative impact on the endemic mollusc fauna and can result in economic losses. The West African land snail Tomostele musaecola (Morelet) was previously recorded from numerous localities in the Western Hemisphere. In this paper, we provide a new locality of this malacophagous snail in the Dominican Republic. The species is recorded from an urban park named Parque Ecológico Las Caobas in the province of San Cristóbal. In order to update the current distribution of T. musaecola in the Americas we examined the literature and the online database of the Invertebrate Zoology Collection of the Florida Museum of Natural History (FLMNH); when available, citizen science data were also used. A map is provided to illustrate the current distribution of the species in the Americas. The total number of records in the Western Hemisphere is 51, and 26 of them are part of this review. More studies are needed on the interaction of this species with the native land snails. Trade and planting of ornamental species in urban parks facilitate the establishment and expansion of alien molluscs.

THE SPREAD OF SHEEP FLUKES ON THE ECOLOGICALY DIFFERENT TYPES OF PASTURES IN THE DAGESTAN LOWLAND

The trematodeses (fascioliasis, dicrocoeliosis, paramphistomatosis) are widespread helminthes of sheep. Animals are infected with pathogens of these helminthes on pastures and near water sources. It is established that these trematodoses are common among sheep with different intensity on ecologically different types of pastures of the Dagestan lowland. So, fascioliasis is recorded among sheep on wet lowland with many waterholes, as well as on steppe ecosystems with irrigation and near permanently functioning artesian wells with wetlands with developed freshwater malacofauna. Paramphistomatosis occur in habitats with permanent water sources with the fauna of freshwater mollusks of the family Planorbidae. Dictyocaulosis among sheep is observed in the dry steppe territories with an abundance of land mollusks and ants. Sheep were infected with fascioles in the Dagestan lowlands with an invasion extensity (IE) of 10.0–26.6%, with an invasion intensity (II) of 5–216 copies, with paramphistomum and calicoforum 3.0–15.8% and 4–140 copies, with dicrocelium 18,0–76,6% and 120–2670 copies, respectively. Mixed infestations of trematodoses, strongylatoses, and larval teniidoses are recorded in the interfluve area of Sulak, Terek, Talovka, and Kuma, as well as near the Arakum, Lower Terek, and Shirokolsky reservoirs.

Systematic descriptions and seasonal variations of mollusc in Chandigarh (U.T., India) and its surrounding freshwater bodies

The present study is the first attempt to study the taxonomy and diversity of molluscan fauna from freshwater bodies of Chandigarh (U.T.) and Ghaggar River flowing on its southeast border. A total of 24 molluscan species (17 gastropods, 3 bivalves and 4 land snails) were collected from the selected sites. Physa acuta was found showing ubiquitous occurrence along with its maximum abundance in all water bodies followed by Melanoides tuberculata. Less biodiversity and the presence of tolerant species indicated that majority of the water bodies under study are under a great threat of degradation. The results of this study will contribute to the knowledge of the regional malacofauna along with identification of the sites facing natural and human interferences.

Identification of the gastropod snails and shells collected from Ain El-Sokhna region, Red Sea, Egypt

The Red Sea is known for its unique coral reef topography that harbors many marine species making the Red Sea a biodiversity hot spot. The molluscan fauna of the Red Sea has been extensively studied for its ecology, biology and economic importance. In the present study, numerous live specimens and gastropod shells were collected from Ain El-Sokhna area on the western shore of the Red Sea’s Gulf of Suez. Samplings were done during June-October, 2020. The collected species were identified based on published keys for the identification of Red Sea molluscs. A total of 24 gastropod species belonging to 12 families were identified. Among these, the highest abundant species was Thais savignyi (Muricidae) followed by Cellana rota (Nacellidea). Some other species were rarely abundant such as Conomurex fasciatus (Strombidae), the reef-eating snail, Drupella cornus (Muricidae), Nassarius fenistratus, N. castus (Nassariidae), and Polinices pecelephanti (Naticidae). The present findings demonstrate high molluscan biodiversity at Ain El-Sokhna region of the Red Sea and set the platform for further studies and assessments of biological and biomedical importance of identified molluscs species either as intermediate hosts for parasites or sources for bioactive compounds.

Richness, abundance and spatial heterogeneity of gastropods and bivalves in coral ecosystems across the Mexican Tropical Pacific

ABSTRACT The diversity of gastropods and bivalves, total mollusc richness and total mollusc abundance were analysed for three substrates (coral, rock and sand) in the coral and reef ecosystems of the Mexican Tropical Pacific (MTP). Up to 3,828 individuals (70% gastropods and 30% bivalves), belonging to 209 species (146 gastropods and 63 bivalves), were identified; this is one of the most diverse molluscan faunas (2.77 species/m2) associated with reef systems in the MTP. Evaluation of the sampling effort demonstrated that 80% of gastropod species and 93% of bivalve species inhabiting the reef system were recovered. The highest abundance occurred in the coral substrate (1,939 individuals), while the highest species richness was found on the rock substrate (131 species). The analysis showed that the greatest spatial variation in total mollusc, gastropod and bivalve diversity occurred among different substrates within individual localities, with minor differences among assemblages with increasing spatial scale reflecting the relative homogeneity of the molluscan fauna in the study area. While the gastropods Conus nux, Steironepion piperatum and Muricopsis zeteki accounted for differences among different regions, and Vermicularia pellucida eburnea and Bostrycapulus aculeatus accounted for differences among states, the abundances of M. zeteki, B. aculeatus and V. pellucida eburnea were related to differences in diversity at the scale of individual localities. Among bivalves, Leiosolenus aristatus, L. plumula and Gastrochaena ovata accounted for differences between regions, states and localities, respectively. Overall, the study shows that species composition is influenced by both the substrate and the geographical location of assemblages. This indicates that conservation strategies should address preserving habitat heterogeneity at local scales in the study area.

Plži Obory Hvězda, Petřína a Vyšehradu v Praze [Gastropods of the Hvězda Game Reserve, Petřín and Vyšehrad in Prague

Mollusc fauna of three protected areas in the capital of the Czech Republic, Prague, was revised after 25 years (Hvězda Game Reserve, Petřín) or studied for the first time (Vyšehrad). In total, 56 molluscs species were found and the survival of endangered species Vertigo angustior and Nesovitrea petronella in the Hvězda Game Reserve was verified. Generally, some sensitive species in well-preserved localities are being replaced by weed species, including non-indigenous ones such as the invasive Arion vulgaris, and the southern element Monacha cartusiana. On the other hand, some woodland species such as Arianta arbustorum, Urticicola umbrosus, Eucobresia diaphana, Arion silvaticus and Lehmannia marginata apparently spread in Prague.

PONTO-CASPIAN AND MEDITERRANEAN FAUNAL AND FLORAL RECORDS OF UPPER PLEISTOCENE-HOLOCENE SEDIMENTS FROM THE İZMİT GULF (MARMARA SEA, TURKEY)

İzmit Gulf is located between Kocaeli and Armutlu peninsulas at east of Marmara Sea and the interaction area of North Anatolian Fault Zone (NAFZ) and Marmara Graben systems. In this study, the faunal and floral contents (ostracod, foraminifer, mollusc and diatom) of the samples belonging to seven drilling cores were studied and obtained the radiocarbon and optically stimulated luminescence (OSL) age data in order to establish on the Black Sea – Marmara Sea - Mediterranean water connections and palaeoenvironmental changes. The sediments in this study are Late Pleistocene-Holocene aged and only cover the Marine Isotope Stages MIS-5 (interglacial), MIS-3 (an interstadial period between MIS-4 and MIS-2 glacial epochs) and MIS-1. The determination of ostracod and mollusc fauna of the Mediterranean and Ponto-Caspian origin provide important clues to water exchange between the Mediterranean and the Black Sea. Although some Mediterranean originated ostracods occur sporadically with low abundance, absence of foraminiferal fauna and existence of Ponto-Caspian ostracods together with fresh water and cosmopolitan diatom flora indicate that the area strongly interacted with the Black Sea waters during MIS-5. The faunal and floral characteristics of the sediments deposited during MIS-3, clearly denote that the Izmit Gulf was connected with the Black Sea and the Mediterranean Sea at the beginning of MIS-3 (ca. 52.0 - 40.0 ky BP) and the shallow shelf areas were frequently affected by both the Black Sea discharge and Mediterranean input. A thick Holocene sedimentary sequence recovered from the southern Hersek Burnu drilling cores reflects the environmental changes after the latest Black-Mediterranean seas connection. The studied ostracod and mollusc assemblages are mainly characterized by the Mediterranean originated species with a few relict Ponto-Caspian fauna. Also, the benthic foraminiferal assemblages are dominated by normal marine and euryhaline species, reflecting the salinity fluctuations in the Holocene interval.

Analysis of the adventitious fauna of terrestrial molluscs in the centre of the Russian Plain

The terrestrial mollusc fauna of the central part of the Russian Plain has been analysed with respect to its species composition and the proportion of adventitious species. The classification of adventitious species follows that accepted in Russia. Considerable changes in the fauna took place in the period 2016–2020. Helix lucorum Linnaeus and Cornu aspersum (O. F. Müller) were added to the terrestrial malacofauna of the area. Within the last four years, Arion vulgaris Moquin-Tandon colonised anthropogenic habitats and its spread continues. Krynickillus melanocephalus Kaleniczenko, Arianta arbustorum (Linnaeus), and Helix pomatia Linnaeus are now firmly established in natural ecosystems. Populations of A. vulgaris, K. melanocephalus, and A. arbustorum have become so abundant that now they cause significant damage to agricultural crops. In both natural and anthropogenic habitats K. melanocephalus and A. arbustorum displace Succinea putris (Linnaeus), Deroceras laeve (O. F. Müller), D. sturanyi (Simroth), D. invadens Reise, Hutchinson, Schunack et Schlitt, 2011, D. agreste (Linnaeus), D. reticulatum (O. F. Müller), Fruticicola fruticum (O. F. Müller) and Euomphalia strigella (Draparnaud). Interactions between invasive species are discussed. The proportion of alien species in several European countries and in Central Asia is compared.

Gigantic scaphopods (Mollusca) from the Permian Akasaka Limestone, central Japan

AbstractPaleozoic scaphopods are among the most poorly known mollusks because of their featureless tubular shell morphology and fragmentary preservation. An apical orifice at the posterior end of a conch is a diagnostic character of Scaphopoda that distinguishes them from other groups of animals that produce similar calcareous tubes, but this structure is rarely preserved. A rich molluscan fauna from the Permian Akasaka Limestone in central Japan includes scaphopod shells, and past studies have reported four species, all of which were based on fragmentary specimens. This study recognizes six species in the Akasaka Limestone mainly on the basis of museum/institution collections, and a new genus (Minodentalium) and three species (Prodentalium onoi,M.hayasakai, andM.okumurai) are described, two known species (P.akasakensisandP.neornatum) are redescribed in more detail, and one species (Prodentaliumsp.) is described under open nomenclature. The following eight known species are allocated to the new genusMinodentalium:Plagioglypta furcataWaterhouse, 1980;Pl.girtyiKnight, 1940;Pl.subannulataEaston, 1962;Dentalium ingensDe Koninck, 1843;D. meekianumGeinitz, 1866;Pl.prosseriMorningstar, 1922;Dentalium priscumMünster in Goldfuss, 1842; andD.herculeumDe Koninck, 1863. All the species, except forM.hayasakai, are gigantic, reaching 200 mm or more in length. The species richness is the greatest known from a single locality/formation worldwide.UUID:http://zoobank.org/35405b9d-3ba7-40bf-87c5-3f2b550b1a6d

Diversity and distribution of molluscan fauna of Asthamudi estuary, Kerala, India

The survey of molluscan fauna of Ashtamudi estuary of the southwest coast of India recorded the presence of 119 species classified under 3 classes (Polyplacophora, Gastropoda and Bivalvia), 57 families and 96 genera. The species diversity was dominated by the Gastropoda (69 species), followed by the Bivalvia (49 species) and the Polyplacophora (1 species). The report includes four species recorded for the first time from India: Desmaulus edgarianus (Melvill, 1898), Pilosabia trigona (Gmelin, 1791), Nassarius javanus (Schepman, 1891) and Jorunna labialis (Eliot, 1908). The true diversity of the mangrove region was as good as that of a community with 31.380 (= 31) equally common species; the respective values for the bar mouth and lake regions were 15.516 and 8.997, respectively, indicating that the molluscan species assemblage of the mangrove was the most diverse and of the lake, the least. True β-diversity across this gradient registered 1.792, which means that though there were three communities, they were equivalent to only 1.792 (= 2) effective communities, i.e., the three actual communities were as different from each other as 2 with equal weights and no species in common.

New Middle Cambrian molluscs from the Láncara Formation of the Cantabrian Mountains (north-western Spain)

An abundant and highly diverse fauna is characteristic for the nodular limestones of the upper member of the Láncara Formation. It consists of echinoderms, trilobites, brachiopods, molluscs, sponge- and chancelloriid remains, and other small shelly fossils. Whereas the trilobites of the Láncara Formation are well investigated, information on other faunal groups is clearly underrepresented. In this paper the Middle Cambrian helcionelloid molluscs and hyoliths of the upper member of the Láncara Formation from four sections are described for the first time. The mollusc fauna shows clear affinities to Siberia, South Australia, Greenland, and China. The following taxa were described: Protowenella lancaraensis new species, Mackinnonia cf. rostrata (Zhou & Xiao, 1984), Pelagiella subangulata (Tate, 1892), Conotheca sp., and Microcornus sp.

Terrestrial gastropods of Humaitá Forest Reserve, southwestern Brazilian Amazon

The molluscan fauna of southwestern Brazilian Amazonia is poorly known due to the lack of focused collection areas in the region since the early 20th century. The present study provides an inventory of the terrestrial gastropods from a forest fragment in the eastern Acre state, Brazil: the Humaitá Forest Reserve (“Reserva Florestal Humaitá”). Live specimens and empty shells were collected between August 2018 and January 2019. A total of 20 species were identified, distributed in 11 families. Most (13) of these species were recorded in Acre for the first time. Furthermore, we confirm the occurrence of Systrophia helicycloides (d’Orbigny, 1835) in Brazil, reiterate the synonymy of Plekocheilus pentadinus (d’Orbigny, 1835) with P. floccosus (Spix in Wagner, 1827), and synonymize Solaropsis peruviana Haas, 1951 with S. juruana Ihering, 1905.

Сучасний стан та особливості таксономічної структури трематод прісноводних молюсків Українського Полісся

The paper presents results on the analysis of the taxonomic structure of the trematode fauna of the Ukrainian Polissia. It was found that the trematode fauna of freshwater molluscs in the Ukrainian Polissia is represented by 62 species. We supplemented the species composition of larvae of trematodes in the region with 23 species, 13 of which were first recorded in Ukraine. The results showed that the number of trematode species the definitive hosts of which are fishes have decreased. According to the obtained data, the most abundant trematode species of freshwater molluscs in the Ukrainian Polissia are those of the families Echinostomatidae, Plagiorchiidae, Diplostomidae, and Notocotylidae. The combined analysis of literature and original data revealed that in the basis of the regional trematode fauna of molluscs are species of the families Echinostomatidae (13 species) and Plagiorchiidae (10 species), which make up almost one-third of the total number of trematode larvae detected. A quite large portion of larvae belong to species of the families Notocotylidae (8 species), Strigeidae (7 species), Diplostomidae (5 species), and Haematolechidae (5 species). Most families (Diplodiscidae, Opisthorchiidae, Leucochloridiomorphidae, Prostogonimidae, Cathaemasiidae, Cyclocoelidae, Prohemistomatidae, and others) are represented only by 1–2 species. In freshwater molluscs of the studied region, we have found only 38 % of trematode species recorded in definitive hosts. Species found in vertebrate animals of the region potentially can also occur in intermediate hosts, but most of these species parasitize in birds that could be infected in other areas. When comparing the taxonomic structure of the trematode fauna of the Polissia with other well-studied regions of Ukraine (Northern Pryazovia and Crimea), some specifics were noted between them. In particular, it was found that the most abundant trematode species in the region as well as in the whole of Ukraine are those of the families Echinostomatidae, Plagiorchiidae, Diplostomidae, Notocotylidae, and Strigeidae. The obtained data allow considering that the trematode fauna of freshwater gastropods of the Ukrainian Polissia is an integral part of the Central European fauna of trematodes.

Dynamic of Mangrove Associated Molluscs in Anthropized Areas of the Cameroon Coastline

Due to unabated anthropogenic exploitations, mangrove forests globally are constantly under pressure and degradation, which may result in the reduction of ecosystem functioning and biodiversity. Molluscan fauna, which is one of the main macroinvertebrates that play a major ecological role in nutrient dynamics in mangroves, are sensitive to the changes in their habitat. This survey aims to assess the impact of anthropogenic activities on the diversity of molluscs’ communities in the mangrove forest. Anthropogenic disturbances within 20 sampling sites were valued at six mangrove stands and patched scoring the degree of influence according to vegetation, structure, waste and trampling. Molluscs were caught by hand and counted within 1 × 1 m2 plots placed at three points distant of 50 m established using a straight line transect of 100 m. Upon the 20 sites investigated, five were slightly disturbed, eight moderately disturbed and seven sites were highly disturbed. The mean abundance of molluscs decreased from slightly disturbed areas (172.25 ± 73.09 Ind·m−2) to highly disturbed areas (100.57 ± 62.84 Ind·m−2). Highly disturbed areas have shown lower species richness (R = 1.09 ± 0.15) and diversity (H’ = 2.30 ± 0.31). Human activities in the mangrove forest could particularly have effects on the diversity of molluscs, however, feature potential conservation measures have to be in harmony with the needs of the local population.

Influence of abiotic factors on biodiversity of the populations of bivalve molluscs of the Lower Zarafshan reservoirs

The length of the reservoir area on the banks of the Zarafshan River and the presence of all biotopes inhabited by molluscs of the Unionidae and Corbisulidae families have made the basin a comfortable aquatic ecosystem for molluscs. The influence of rivers and fisheries on the formation of the fauna of bivalve molluscs in reservoirs is significant. We found that 10 species and 2 subspecies of bivalve molluscs were distributed in the Kuymazor reservoir and 8 species and 2 subspecies of bivalve molluscs in Shurkul. Reservoirs of Sinanodonta species are shown for the first time by us. These molluscs belong to the ecological groups like peloreophilic, rheophilic and pelolimnophilic. In the water reservoirs of Uzbekistan, the spread of bivalve molluscs by groups has common features. In all water reservoirs, an ecological group called peloreophil prevails, but the species belonging to the ecological group atre different in different water bodies. Such species of pedloelphils as Sinanodonta gibba, S. orbicularis, Corbiculina tibetensis and C. ferghanensis are predominantly found in rivers, fish farms, and water reservoirs. The most common species in the canals are Corbiculina tibetensis and C. ferghanensis. The next frequent occurrence in water reservoirs is the ecological group of rheophiles.

Malacofauna of lotic environments in the Northeast and Brazilian semiarid region: current knowledge and new records.

Despite the great diversity, economic and environmental importance of limnic mollusks, the group is still little investigated in the Brazilian semiarid region, especially in the state of Piauí. Thus, this work aims to gather information on the diversity of limnic mollusks in the Brazilian Northeast and the semiarid region, including new records for the state of Piauí, northeastern Brazil. For this, collections in the urban perimeter of the Itaim and Guaribas Rivers, municipalities of Itainópolis, and Picos, respectively, between October 2017 and September 2019. Besides, a literature review was conducted on studies of malacofauna in the Northeast and the Brazilian semiarid region. A total of 11 species from the classes Gastropoda and Bivalvia were collected on the rivers of Piauí, being the first record of Uncancylus concentricus for the Northeast region. For lotic environments in the state of Piauí, Drepanotrema schubarti, Pomacea canaliculata, Pisidium dorbignyi and Stenophysa marmorata were registered for the first time. Then, it was possible to verify that the Northeast of Brazil has 71 species registered, of which 34 occur in the semiarid. The diversity of species surveyed and the first record of the occurrence of several of them for the semiarid region demonstrate the importance of expanding studies involving this group to other areas. The present study is the first to gather and increase the information available on the fauna of limnic mollusks for the Northeast and Brazilian semiarid regions. The information gathered here may contribute to future research and to the species conservation and the environments they occupy, especially considering the presence of non- native and vector species.

Bivalve mollusk fauna and ecological groups of Unionidae and Corbiculidae families in natural and artificial reservoirs of Uzbekistan

The length of the rivers in Uzbekistan and the presence of all the biotopes in the mollusks have made they a favourable reservoir for the mollusks. However, it should be noted that all species in the rivers differ in their density. Rivers and fishery farms play a great role in formation of bivalve mollusks fauna in the canals. It was studied the fishery farms of the Syrdarya River and its surroundings have a major effect on the fauna of the Mirzachul and South Mirzachul canals; the Zarafshan River’s effect on spreading of bivalve mollusks in the Dargom and Eskiankhor canals; the Amudarya River and its surrounding areas influence of fishery farms on the fauna of the Amu-Bukhara, Kizketgan and Karshi main canals. Colletopterum family breeds in the water studied, do not show any superiority in natural or artificial reservoirs compared to other breeds. Three species of these family are included in the Red Book of the Republic of Uzbekistan (C.baсtrianum, C. cyreum sogdianum, C. kokandicum). C. Bactrianum can be found only in rivers in the middle Zarafshan and Amudarya, in the Syrdarya river (Syrdarya Region only), in the reservoir and in the fishery farms only in Chelak, and the canals only in the Tuyatortar and Mirzachul canals.