The Allocation of Some Pelagic Larvae of Bivalve Mollusks in the Western Part of Chukchi Sea

Collected in September-October 2016 in the 48th cruise of SRS “Academician Oparin” the plankton samples with the assistance of Norpac net with the cell of 150 μm in the horizon 15-0 m have shown the plenty of pelagic larvae of bivalve mollusk in Chukchi Sea. Its biggest quantity was found in the period from the 22nd of September until the 1st of October. The most yield area was situated on the opposite side of the Bering Strait and the second maximum of larvae quantity was found on the Herald’s bank. Most valuable factors influencing the territorial allocation of the researched larvae are the water surface temperature and the water depth.

Differences in Trace Element Content between Non-Indigenous Farmed and Invasive Bivalve Mollusks of the South African Coast

contents of 23 trace elements (Sc, V, Cr, Mn, Fe, Co, Zn, As, Se, Br, Rb, Sr, Mo, Ag, Sb, I, Ba, La, Ce, Sm, Eu, Hf, Ta) were quantitatively determined in soft tissues and shells of mass non-indigenous bivalve mussels—farmed Pacific oysters (Crassostrea gigas) and farmed and wild invasive Mediterranean mussels (Mytilus galloprovincialis) at the Atlantic coast of South Africa. The study revealed that the contents of the majority of elements in the soft tissues of both species were higher than those in the shells. The tissues of wild invasive Mediterranean mussels contain higher levels of a range of trace elements comparing to farmed mussels. The tissues of Pacific oysters contain much higher levels of almost all elements studied compared to the tissues of Mediterranean mussels. Higher content of zinc in the mussels and oysters from Saldanha Bay may evidence anthropogenic pollution of the bay’s ecosystem by this metal, which necessitates continued monitoring of levels of potentially toxic metals. Both alien species, and especially Pacific oysters, may serve as reliable biomonitors for trace elements in marine ecosystems. Both species are rich in essential elements and provide nutritionally-valuable seafoods.

Commercially Important Marine Mollusks for Human Consumption in Acapulco,Mexico

Acapulco, offers for international tourism a variety of mollusks that are delightful to the palate and a source of economic revenue for its residents;however there are no studies on the species consumed. Furthermore, data from the State agencies responsible for registration of these products are unclear. This work is aimed to develop an inventory of Gastropoda, Bivalvia and Polyplacophora marketed as food, to gain knowledge on the species native to Acapulco and the introduced ones. The places that sell shellfish were interviewed from 2008 to 2011 in order to determine the geographical origin of their products being offered. We identified 42 species: 15 species of gastropods are captured locally and three are introduced. On Bivalvia, seven species are caught locally and 16 are introduced. There are Bivalvia species caught locally;however, their capture is now unaffordable. It is likely that this situation is due to overfishing and/or the transmission of diseases or parasites caused by the introduction of foreign living organisms to Acapulco. Within the list of species caught locally, there are some listed as of subject protection;all of these organisms are exploited in Acapulco without control. The wealth of marine mollusks for human consumption in Acapulco is very high. The capture does not satisfy local market demand and the amount of introduced species is very high. It is necessary to make a diagnostic analysis of mollusk fishing industry in the state of Guerrero, also implement a management program, including the sanitary measures and control of introduced species, as they arrive alive and stay alive in the waters of Acapulco. A significant number of native species that have aquaculture potential should be studied for commercial culture practice as well as to conduct studies on their biology on those species that are considered over-exploited and allow recovery of the species in its habitat.

Mollusks of the Rocky Intertidal Zone at Three Sites in Oaxaca,Mexico

The community of mollusks at three rocky intertidal zone in Oaxaca, Mexico was analyzed. Two samplings per site were conducted. At each sampling the inspected area was 10 m2. The sampling unit was 1 m2. 5862 specimens were examined. 68 mollusks species were identified. The families better represented in species richness were: FISSURELLIDAE, MURICIDAE, LOTIIDAE, MYTILIDAE, CHAMIDAE, ISCHNOCHITONIDAE y CHITONIDAE. The species that had the greatest density were Lottia discors, Siphonaria palmata, Lottia acutapex, Chormoytilus palliopunctatus, Brachidontes adamsianus, Chton articulatus e Ischnochiton muscarius. The species with the widest distribution represent 11.76%. With irregular distribution was found in 58.82% of the species. The gastropod Crucibulummonticulus, the bivalve C. palliopunctatus and the polyplacophoran C. articulatus had the greatest size. The value of diversity index was H’ = 4.29 bits/ind. and J’ = 0.72. The mollusks community in the rocky intertidal zone study sites is characterized by small size, because they rarely exceed seventy millimeters. The values of H’ and J’ indicate that the mollusk community in the study area has a high diversity and high uniformity, corresponding to mature and stable communities in a tropical region.

Findings on three endocommensal scuticociliates(Protista,Ciliophora)from freshwater mollusks,including their morphology and molecular phylogeny with descriptions of two new species

Species of the ciliate genera Myxophyllum and Conchophthirus are found as endocommensals of terrestrial and freshwater mollusks,respectively.So far,there have been few studies of these genera and morphological data for most members are often incomplete.In the present work,two new species,Myxophyllum weishanense sp.nov.and Conchophthirus paracurtus sp.nov.,and a known species,Conchophthirus lamellidens,were isolated from hosts in Lake Weishan Wetland,China.Taxonomic studies indicate that M.weishanense sp.nov.can be recognized mainly by the combination of about 60 somatic kineties on both ventral and dorsal sides and the presence of caudal cilia.Conchophthirus paracurtus sp.nov.differs from congeners in its body shape and size,having a glabrous area on the posterior right side,and having fewer somatic kineties.In addition,differences in their ITS2(Internally Transcribed Spacer 2)secondary structures support the discrimination of the two new species from their highly similar congeners.An improved diagnosis for the poorly known species,C.lamel-lidens is also provided.Phylogenetic analyses reveal that members of the genus Myxophyllum belong to a fully supported clade that is sister to a large,poorly supported clade consisting of Hemispeiridae,Ancistridae,and several lineages of the nonmonophyletic Cyclidiidae.The Myxophyllum clade also includes Protophyra ovicola JQ956552,a possible misidenti-fication.Sequences of the two new Conchophthirus species cluster with other congeners in a fully supported clade that is unrelated to either the‘typical’thigmotrichs or to pleuronematids,thus conflicting with the traditional classification,and may represent an orphan scuticociliate lineage.

Distribution of methylsiloxanes in benthic mollusks from the Chinese Bohai Sea

Methylsiloxanes are a class of silicone compounds that have been widely used in various industrial processes and personal care products for several decades. This study investigated the spatial distribution of three cyclic methylsiloxanes(D4–D6) and twelve linear methylsiloxanes(L5–L16) in mollusks collected from seven cities along the Bohai Sea. D4–D6(df = 71%–81%) and L8–L16(df = 32%–40%) were frequently detectable in the mollusk samples, while L5–L7 were not found in any mollusk samples. Cyclic methylsiloxanes(D4–D6) were found in mollusks with the mean concentrations of 15.7 ± 12.3 ng/g ww for D4,24.6 ± 15.8 ng/g ww for D5 and 34.0 ± 23.0 ng/g ww for D6. Among the seven sampling cities, the cyclic methylsiloxanes were predominant in mollusks, with the total cyclic methylsiloxanes(sum of D4–D6, ∑ CMS) accounting for 74.2%–80.7% of the total methylsiloxanes. ∑ CMS along the coastline demonstrated a clear gradient, with the highest concentrations in mollusks at the sampling sites located in the western part of the Bohai Sea and the lowest concentrations in mollusks from cities located in the eastern part of the Bohai Sea. The biota-sediment accumulation factors for cyclic methylsiloxanes(D4–D6) and linear methylsiloxanes(L8–L16) were estimated as 0.42 ± 0.06–0.53 ± 0.06 and0.13 ± 0.03–0.19 ± 0.05, respectively.

Microstructural Dependence of Friction and Wear Behavior in Biological Shells

As an essential renewable mineral resource,mollusk shells can be used as handicrafts,building materials,adsor-bents,etc.However,there are few reports on the wear resistance of their structures.The Vicker’s hardness and friction,and wear resistance of different microstructures in mollusk shells were comparatively studied in the pre-sent work.The hardness of prismatic structures is lower than that of cross-lamellar and nacreous structures.How-ever,the experimental results of sliding tests indicate that the prismatic structure exhibits the best anti-wear ability compared with foliated,crossed-lamellar,and nacreous structures.The anti-wear and hardness do not present a positive correlation,as the wear resistance properties of different microstructures in mollusk shells are governed jointly by organic matrix,structural arrangement,and basic building block actions.The present researchfindings are expected to provide fundamental insight into the design of renewable bionic materials with high wear resistance.

Reclassification of Oligodon ningshaanensis Yuan, 1983(Ophidia:Colubridae) into a New Genus, Stichophanes gen. nov. with Description on Its Malacophagous Behavior

The complete mitochondrial cytb gene and the partial nuclear c-mos gene of Oligodon ningshaanensis Yuan, 1983 were sequenced and used for reconstructing the phylogenetic relationship of this taxon amongst alethinophidian snakes. Its strong affinity to the New World subfamily Dipsadinae and the Old World species Thermophis baileyi was inferred. Hemipenial morphology found by authors conflicts with the original description and its similarity with those of the dipsadid snakes is in accordance with our molecular results. Feeding tests show that O. ningshaanensis is a malacophagous predator, which is another matchless character for this species. This behavior is described and compared with other known slug- and snail-feeding snakes. The discovery of the particular position of our subject indicates that erecting a new genus is necessary accommodate this unique species.

Marine Species Introduced on the French Channel-Atlantic Coasts: A Review of Main Biological Invasions and Impacts

The impacts of anthropogenisation modify permanently the distribution patterns of brackish and marine species. Globalization leads to a rapid increase of the numbers of introduced species anywhere in the world. Biological invasions often result in significant losses in the economic value, biological diversity and function of invaded ecosystems. This review presents the main pathways of introduction of non-indigenous species and the main benthic taxonomic groups being established and/or invasive along the French Channel-Atlantic coasts. A focus is put on main invasive marine species in the intertidal and subtidal zones of Brittany (France), among macroalgae (Sargassum muticum, Grateloupia turuturu, Undaria pinnatifida, Codium fragile and Gracilaria vermiculophylla), halophytes (Spartina alterniflora) and benthic invertebrates (Mollusks: Crepidula fornicata, Crassostrea gigas and Venerupis philippinarum). The species biology, introduction vectors, reproductive and dispersal capacities are considered, together with proliferation patterns along the Channel-Atlantic coasts. The ecological impacts of these species on the environment are also described, as well as the European regulations existing to limit alien species introduction and some examples of struggle against the invaders including eradication trials and biomass valorization. Last, the on-going impacts of global changes on alien species invasiveness along the Channel-Atlantic coasts are discussed.

Occurrence and Distribution of Marsh Clam, <em>Polymesoda</em>spp. in Marudu Bay, Sabah, Malaysia

Marudu Bay is part of the Tun Mustapha Marine Park, the largest marine protected area within the Malaysian region of the Coral Triangle Initiative. The bay is known for its diversed fisheries resources including bivalves. Although some of these bivalve species are commercially important, their occurrence, distribution and stock status in the bay are not well documented. Hence, the current study was conducted to determine the occurrence, distribution and the stock status of marsh clam, Polymerasoda spp. in the mangrove swamp situated at the southernmost of the Marudu Bay. Samplings were carried out at the mangrove swamps which covered an area of 500 sequare meter per sampling site. Two marsh clams species, Polymesoda erosa and P. expansa were found to inhabit the sampling sites. In general, juvenile marsh clams were noticed to dominate the seaward mangrove swamp, whereas the high tidal regions were dominated by adults. The current study also suggested a link in the distribution and the morphometric measurements of the marsh clams with the sediment grain size.

Campanian Climatic Change:Isotopic Evidence from Far East,North America,North Atlantic and Western Europe

Paleoclimatic settings have been reconstructed for the Campanian using original oxygenisotopic analyses of well-preserved molluskan and foraminifera shells from Russian Far East, Hokkaido, USA, Belgium and some DSDP holes （95, 98, 102, 390A, and 392A） in North Atlantic. Early Early Campanian climatic optimum has been recognized from data on high bottom shelf water paleotemperatures in middle latitudes of both the western circum-Pacific （to 24.2℃） and the eastern circum-Pacific （to 26.4℃） areas and high bottom shallow water paleotemperatures in high latitudes of the Koryak Upland （22.4-25.5℃）, which agrees with the data on the Campanian Barykovskaya flora in high latitudes （Golovneva and Herman, 1998） and Jonker flora and its equivalents in middle latitudes. Judging from the data on comparatively high bottom shallow water paleotemperature values in high latitudes, South Alaska （19.4℃） and the Koryak Upland （22.4-25.5℃）, we also expect Latest Campauian temperature maximum, which has not been confirmed, however, for low and middle latitudes by neither of isotopic nor paleobotanic data now. Main dimatic tendency during the Campanian （with the exception of Latest Campanian） has been learned from isotopic composition of Campanian aragonitic ammonoid shells from the Hokkaido-South Sakhalin （Krilyon） marine basin. In contrary to Huber＇s et al. （2002） assumption, we expect warm greenhouse conditions during the most part of the Campanian.

New Early Cambrian Maikhanellids(Mollusca) from Zhangjiagou Section, South Shaanxi, China

A new maikhanellid genus, Totornatus gen. nov., from the Lower Cambrian(Fortunian Stage) of Zhangjiagou section at Xixiang County, southern Shaanxi Province, South China, is based on a new taxon T. strigatus gen. et sp. nov. Although showing similar morphology with a cap-shaped shell and an oval aperture to other members of the family, the new species differs from previous maikhanellids in its smooth apex. The apical field consists of dense, small, round or oval granules, which gradually merge to bigger, elongated, scale-like protrusions toward the apertural margin. On this basis, we establish Totornatus strigatus, which shows a transverse groove in two-ninths of its shell. This result enriches the diversity of the earliest mollusks and maikhanellids.

Rudists(Bivalvia) from a Cretaceous Platform in Northern Egypt: Taxonomy and Paleobiogeography

New well-preserved rudist materials come from the Barremian–Turonian marine formations in the Yelleg, Minsherah, Maaza, and Raghawi sections in North Sinai, northern Egypt. There, 17 discovered rudist species belonging to 13 genera and seven taxonomic families are described in detail as follows: Eoradiolites plicatus(Conrad), Eoradiolites liratus(Conrad), Praeradiolites ponsianus(d'Archiac), Archaeoradiolites sp., Bournonia africana Douvillé, Bournonia fourtaui Douville, Biradiolites lombricalis(d'Orbigny), Biradiolites zumoffeni Douville, Radiolites lewyi lewyi Parnes, Radiolites sauvagesi(d'Hombres-Firmas), Durania arnaudi(Choffat), Toucasia carinata(Matheron), Toucasia sp., Neocaprina raghawiensis Steuber and Bachmann, Sellaea sp., Ichthyosarcolites sp. and Horoiopleura sp.. The Cenomanian deposits in the northern Eastern desert of Egypt only contain E. liratus. The domination of the Cenomanian rudist species in North Sinai, however, is attributed to changes in the platform, which passes mainly from carbonate in the north to siliciclastics in the south. The presence of Horiopleura sp. in the late Barremian-early Aptian deposits is documented for the first time, which suggests the expansion of taxa of the genus Horiopleura Douville to North Sinai during this interval. The age of the rudist species is documented from the late Barremian-Turonian formations, with their geographic distribution in the Mediterranean region considered..

Behavioral and Physiological Responses of Sea Slug (Onchidium reevesii) to Low-Frequency Noise

A large amount of marine noise pollution from coastal industrial construction and the water transportation industry affects the growth and development of marine life,which is a big issue threatening marine organisms.However,most studies have focused on vertebrates,such as marine mammals and fishes,and little is known about the effects of noise on invertebrates.Therefore,the impacts of low-frequency noise(100,300,and 500 Hz)on behavioral and physiological responsesof the sea slug(Onchidium reevesii)were investigated.Under laboratory conditions,sea slugs were stimulated with low-frequency noise at 100,300,and 500 Hz for 1 h.Then,hemolymph enzyme activities(glucose,albumin,triglycerides,superoxide dismutase,catalase,and malondialdehyde)were measured,and mRNA expression of the hsp70 gene was detected in hemolymph and the nervous system by quantitative realtime polymerase chain reaction(qRT-PCR)analysis,while expression of the hsp70 protein was analyzed by immunohistochemistry.The results demonstrated that sea slugs were away from the stimulus source under the influence of low-frequency noise compared to the control group.Enzyme activities,as well as hsp70 gene mRNA and protein expression levels,were significantly higher in the noiseexposed groups than those in the control group.Overall,these changes indicate that low-frequency noise caused oxidative stress in sea slugs in vivo,and the oxidative damage gradually increased when the noise frequency was increased from 100 to 500 Hz.

Changes in Mangrove Epifaunal Assemblages Caused by Forest Logging during Hunting of the Neotropical Cormorant (<i>Phalacrocorax brasilianus</i>) on the Colombian Pacific Coast

Although the importance of mangroves is clearly recognized around the world, these ecosystems are being strongly altered by the logging of their forests for multiple purposes. The Colombian Pacific coast is not an exception to this situation, and apart from the traditional logging of wood, the hunting of the Neotropical Cormorant or Pato-cuervo (Phalacrocorax brasilianus), an activity largely unknown but widespread in the region, is also causing the logging of great extensions of mangroves. The aim of this research was to determine if the assemblages of mollusks and crustaceans of these mangroves are being affected by the hunting of the cormorant. To answer this question, quantitative samplings were realized in four transects in logged and unlogged mangrove areas on the southwestern coast of the Colombian Pacific and diversity, equitability and dominance of macrofaunal assemblages of mangroves were calculated. The data show that although significant differences between diversity indices were not found, there were important differences in equitability (total J’: 0.55 in T1, 0.77 in T2, 0.46 in T3 and 0.65 in T4), specific dominance, and composition of species (T1: 11 species, T2: 13, T3: 9 and T4: 11) between logged and unlogged areas. Based on these results, although forest structure and interstitial salinity were different among transects, we conclude that the present practice of exploitation of the Neotropical Cormorant is affecting the epifaunal populations of mangroves, causing changes in the composition and dominance of species.

Macrofossil Assemblages in the Ryazanian Stage (Lower Cretaceous) of the Stratotype Region

The stratotype region of the Ryazanian stage is located in the Oka River Basin near Ryazan, Central Russia. Since ammonites are very well studied here, we investigated other groups of macrofossils. We report a large number of bivalve genera: Arctica, Astarte, Buchia, Camptonectes, Chlamys, Ctenostreon, Entolium, Gomomya, Gresslya, Hartwellia, Lima, Meleagrinella, Modiolus, Oxytoma, and Pleuromya. The belemnites are represented by two cylindroteuthidid genera, Acroteuthis and Liobelus. In addition, brachiopods (Rhynchonellidae and Terebratulidae) and unidentifiable gastropod fragments have been revealed. The highest taxonomic diversity of macrofauna is observed in the Surites spasskensis ammonite Zone.

Mollusk Species Richness on the Rocky Shores of the State of Guerrero, Mexico, as Affected by Rains and Their Geographical Distribution

Natural processes in ecosystems shows significant variations in species richness with regular cycles that can be altered by natural or anthropogenic activities;the present research was in order to understand on some of these variations. The objectives were: 1) determine the species richness of rocky intertidal mollusks;2) track their geographical distribution at State level;and 3) determine the changes in species richness as a result of rainfall on an annual cycle. For these purposes it was sampled in March, June, September and December 2005, the sampled area was 20 m2for each collecting site;the sampling unit was a PVC rectangle frame one by two meter per side. The mollusks found within the sampling units were collected, identified and counted. The species distribution was analyzed by sites and regions, considered species richness per season, and the distributional patterns by rainy season historical records. A total of 62 mollusks species were found, its richness associated with substrate stability and wave intensity on each site, Gastropods had the highest species richness. When analyzing the regional distribution and sites, it was found a pattern of species richness roughly constant in the proportion of species with wide distribution (generalists) versus those of restricted spatial representation (specialists). Gastropods had the highest number of species with restricted spatial representation. Seasonal rainfall differences did not quantitatively altered on the overall the species of mollusks in the rocky intertidal sampled zone however, in the analysis per Class, Gastropoda indicated changes in species richness influenced by rainfall, which were not observed in Bivalvia and Polyplacophora, suggesting that those changes might depend on adaptive processes or the lack of adaptation of gastropod species to the characteristics of the rocky intertidal habitat.

Effects of dietary vitamin A on antioxidant responses of abalone Haliotis discus hannai Ino

A 240 d growth experiment was conducted in a re-circulated water system to investigate the effects of dietary vitamin A on growth and antioxidant responses of abalone Haliotis discus hannai Ino. Triplicate groups of juvenile abalone [ initial mass was （0.96±0. 02） g, shell length was （17.70±0.06） mm] were fed to satiation one of three send-purified diets containing 0, 1×10^3, 1×10^6 IU vitamin A per kilogram diet, respectively. Results showed that the daily increment in shell length （DISL） of abalone in the treatment with 1 × 10^3 IU vitamin A per kilogram diet was significantly higher than that with 0 or 1 × 10^6 IU vitamin A per kilogram supplementation （P 〈 0.05）. Vitamin A deficiency （0 IU/kg） significantly elevated the activities of superoxide dismutase （SOD）, glutathione peroxidase （GPX） and glutathione reductase （GR） in the viscera of abalone （P 〈 0.05）. In muscle, the effects of vitamin A deficiency on SOD and GPX activities were the same as those in viscera, however, the activity of GR significantly decreased （P 〈 0.05）. Vitamin A deficiency significantly decreased the ratio of CAT to SOD （eatalase/superoxide dismutase） in viscera （P 〈 0.05）. Nevertheless, it significantly decreased the ratio of GR to GPX in muscle （P 〈 0.05）. Compared with the supplement of 1 x 103 IU vitamin A per kilogram, excessive vitamin A （ 1 × 106 IU/kg） had no significant effects on the activities of CAT, SOD and glutathione-S-transferase （GST） （P 〉 0.05）, but significantly elevated GPX and GR activities in viscera （P 〈 0. 05）. In muscle, the activities of CAT, SOD, GPX, GST and GR were significantly decreased by the excessive dietary vitamin A supplement （P 〈 0.05）. Compared with the supplement of 1×10^3 IU vitamin A per kilogram, vitamin A-excessive had no significant effect on the value of ratio of CAT to SOD either in viscera or in muscle （ P 〉0.05 ）. The ratio of GR to GPX was significantly decreased in viscera, but significantly elevated in muscle in the vitamin A-excessive group （P 〈 0.05 ）. In conclusion, optimum supplement of vitamin A （ 1 × 103 IU/kg） was beneficial for abalone to maintain maximum growth and antioxidant system. Hypoor hyper-vitaminosis A would decrease growth and the efficiency of scavenging reactive oxygen species （ROS） of abalone.

The transcription of iodothyronine deiodinase genes is regulated by thyroid hormone receptor in the Pacific oyster Crassostrea gigas

Thyroid hormones (THs) are indispensable for each phyla in Chordata, while their functions in the non-chordate invertebrates are indistinct. Studies on the TH system in non-chordate invertebrates are important for understanding the evolution of TH system and may be applied in aquaculture or biofouling control at the same time. Iodothyronine deiodinases are keys to studying the TH system, as they are critical enzymes in maintaining TH homeostasis by catalyzing the initiation and termination of the effects of thyroid hormone in vertebrates. Here, we report the primary physiological effects of T4, the outer ring deiodinase activity, and a similar transcription regulation of two oyster deiodinases by TH receptor (CgTR) in an invertebrate, Pacific oyster Crassostrea gigas. L-thyroxine (T4) may have an important physiological function in the oyster, suggested by the growth retardation effect of excessive T4 in umbo larvae stage. The outer ring deiodinase activity transforming T4 to T3 (3, 3', 5-triiodothyronine) was then detected in the Pacific oyster in vivo, which may be conducted by two oyster deiodinases (CgDx and CgDy). Transcription regulation of CgTR onto these two deiodinase genes was also verified by electrophoretic mobility shift assay and dual luciferase reporter assay in mammalian cells. These results contribute to a better understanding of the evolution of the TH system.

Taxonomical and Biogeochemical Investigation of Elements in Holocene Mollusk Shells in the South and Southwestern Marmara Basin,Turkey

Concentrations of some heavy metals and trace elements such as Cr, Ga, Ni, Zn, Mo, Cu, Pb, Yb, Y, Nb, Ti, Sr, Ba, Mn, Sc, Co, V, Zr, Fe, Al, W, Se, Bi, Sb, As, Cd in recent mollusk shells and factors affecting their distribution and deposits collected from various depths in the southern and southwestern parts of the Marmara Sea are investigated. The distribution of the elements in the shells is categorized into four groups. Of these, concentrations of 12 elements （As, Bi, Cd, Co, Ga, Mo, Nb, Sb, Se, Sc, W and Yb） are below zero [（0.053-0.79）×10^-6]; concentrations of seven elements （Cr, Ni, Pb, V, Y, Zr and Cu） are （1.0-6.0）×10^-6; concentrations of four elements （Ti, Mn, Ba and Zn） are 10- 20×10^-6; and concentrations of five elements （Si, Al, Fe, Mg and Sr） are （47.44-268.11）×10^-6. The taxonomic characteristics of the 29 elements were studied separately in mollusk shells such as Chamalea gallina （Linn6）, Pitar rudis （Poli）, Nassarius reticulatus （Linn6）, Venerupis senescens （Coocconi）, Mytilus galloprovincialis （Lamarck）, Mytilaster lineatus （Gemelin in Linne） and Chlamys glabra. It was found that, in mollusk taxonomy, the elements have unique values. In other words, element concentrations in various mollusk shells depend mainly on the taxonomic characteristics of mollusks. In various bionomic environments different element distributions of the same species are attributed to the different geochemical characters of the each environment. Data obtained in this study indicate that the organisms are the most active and deterministic factors of the environment.