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Sample records for chiton granosus frembly

  1. The shallow-water chitons (Mollusca, Polyplacophora of Caldera, Region of Atacama, northern Chile

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    Juan Francisco Araya

    2015-03-01

    Full Text Available The Molluscan species of the northern littoral of Chile have been sparsely studied. This work reviews for the first time the diversity of polyplacophoran molluscs around the port of Caldera, in the Region of Atacama (26°45’49”S; 70°45’17”W to 27°20’23”S; 70°56’46”W, northern Chile. Eleven species were found in this study: Acanthopleura echinata (Barnes, 1824; Callistochiton pulchellus (Gray, 1828; Calloplax vivipara (Plate, 1899, Chaetopleura peruviana (Lamarck, 1819; Chiton cumingsii Frembly, 1827; Chiton granosus Frembly, 1827; Chiton magnificus Deshayes, 1827; Enoplochiton niger (Barnes, 1824, Radsia barnesii (Gray, 1828, Tonicia atrata (G. B. Sowerby II, 1840 and Tonicia chilensis (Frembly, 1827. All of the species occurring in the area have distributions in the southeastern Pacific Ocean, from Ecuador to central Chile, and three of them are species endemic to the Chilean coasts (Calloplax vivipara, Radsia barnesii, and Tonicia atrata. This diversity of species is comparable to that of better surveyed faunas of central and southern Chile or Patagonia. Of the eleven species recorded, the geographic distribution records for Callistochiton pulchellus, Radsia barnesii and Tonicia atrata are extended, and Calloplax vivipara is found alive again after 40 years, filling a gap in its known distribution. Illustrations of living specimens in their habitat, distribution records and a taxonomic key for all the studied taxa are also provided.

  2. The male of Megacormus granosus (Gervais, 1844) with comments on its hemispermatophore (Scorpiones, Euscorpiidae)

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    Edmundo González-Santillán; Fernando Alvarez Padilla

    2015-01-01

    Abstract The male of Megacormus granosus is described for the first time and the female redescribed. A homology scheme proposed recently is applied to hemispermatophore structures. The specimens were collected in an oak forest from Pico de Orizaba Volcano at an average altitude of 2340 m. All adult males were collected by pitfall traps, whereas all adult females and both sex immatures were collected using Berlese funnels, suggesting that males are comparatively more mobile within the leaf lit...

  3. The male of Megacormus granosus (Gervais, 1844 with comments on its hemispermatophore (Scorpiones, Euscorpiidae

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    Edmundo González-Santillán

    2015-05-01

    Full Text Available The male of Megacormus granosus is described for the first time and the female redescribed. A homology scheme proposed recently is applied to hemispermatophore structures. The specimens were collected in an oak forest from Pico de Orizaba Volcano at an average altitude of 2340 m. All adult males were collected by pitfall traps, whereas all adult females and both sex immatures were collected using Berlese funnels, suggesting that males are comparatively more mobile within the leaf litter layer, probably due to mating season.

  4. Lorentz Spengler's descriptions of chitons (Mollusca: Polyplacophora)

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    Kaas, P.; Knudsen, J.

    1992-01-01

    The present paper deals with an important Danish paper on the Polyplacophora, published in 1797 by Lorentz Spengler: Udförlig Beskrivelse over det mangeskallede Konkylie-Slaegt, af Linnaeus kaldet Chiton; med endeel nye Arter og Varieteter. -Skrivter af Naturhistorie-Selskabet, 4e Bind, Ie Hefte, VI

  5. Magnetic Anisotropy in the Radula of Chiton

    Institute of Scientific and Technical Information of China (English)

    ZHAO Jian-Gao; QIAN Xia; LIU Wei; LIU Chuan-lin; ZHAN Wen-Shan

    2000-01-01

    Radular teeth of chitons were studied by using magnetic torque-meter and transmission electron microscopy (TEM). The magnetic torque curves give clear evidence of presence of strong uni-axial magnetic anisotropy. The easy axis is along the length direction of tongue-like radula. The TEM pattern shows that long chip-like magnetite nano-scaled particles packed in the radular teeth with both uni-axial shape anisotropy and magneto-crystalline anisotropy.

  6. Magnetic Anisotropy in the Radula of Chiton

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    Zhao, Jian-Gao; Qian, Xia; Liu, Wei; Liu, Chuan-Lin; Zhan, Wen-Shan

    2000-07-01

    Radular teeth of chitons were studied by using magnetic torque-meter and transmission electron microscopy (TEM). The magnetic torque curves give clear evidence of presence of strong uni-axial magnetic anisotropy. The easy axis is along the length direction of tongue-like radula. The TEM pattern shows that long chip-like magnetite nano-scaled particles packed in the radular teeth with both uni-axial shape anisotropy and magneto-crystalline anisotropy.

  7. Upper Cambrian chitons (Mollusca, polyplacophora) from Missouri, USA

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    Pojeta, J.; Vendrasco, M.J.; Darrough, G.

    2010-01-01

    Numerous new specimens reveal a greater presence of chitons in Upper Cambrian rocks than previously suspected. Evidence is presented showing that the chiton esthete sensory system is present in all chiton species in this study at the very beginning of the known polyplacophoran fossil record. The stratigraphic occurrences and paleobiogeography of Late Cambrian chitons are documented. The 14 previously-named families of Cambrian and Ordovician chitons are reviewed and analyzed. Aulochitonidae n. fam. is defined, based on Aulochiton n. gen.; A. sannerae n. sp. is also defined. The long misunderstood family Preacanthochitonidae and its type genus Preacanthochiton Bergenhayn, 1960, are placed in synonymy with Mattheviidae and Chelodes Davidson & King, 1874, respectively; Eochelodes Marek, 1962, also is placed in synonymy with Chelodes, and Elongata Stinchcomb & Darrough, 1995, is placed in synonymy with Hemithecella Ulrich & Bridge, 1941. At the species level, H. elongata Stinchcomb & Darrough, 1995, and Elongata perplexa Stinchcomb & Darrough, 1995, are placed in synonymy with H. eminensis Stinchcomb & Darrough, 1995. The Ordovician species H. abrupta Stinchcomb & Darrough, 1995, is transferred to the genus Chelodes as C. abrupta (Stinchcomb & Darrough, 1995). The Ordovician species Preacanthochiton baueri Hoare & Pojeta, 2006, is transferred to the genus Helminthochiton as H. ? baueri (Hoare & Pojeta, 2006). The Ordovician species H. marginatus Hoare & Pojeta, 2006, is transferred to the genus Litochiton as L. marginatus (Hoare & Pojeta, 2006). Matthevia walcotti Runnegar, Pojeta, Taylor, & Collins, 1979, is treated as a synonym of Hemithecella expansa Ulrich & Bridge, 1941. In addition, other multivalved Cambrian mollusks are discussed; within this group, Dycheiidae n. fam. is defined, as well as Paradycheia dorisae n. gen. and n. sp. Cladistic analysis indicates a close relationship among the genera here assigned to the Mattheviidae, and between Echinochiton Pojeta

  8. Chitons (Mollusca: Polyplacophora) procured by the CANCAP I-VII expeditions, 1976-86

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    Kaas, P.

    1991-01-01

    The 327 specimens of chitons captured during six out of seven CANCAP Expeditions have been examined. They belong to 26 species, including two recently described ones: Ischnochiton (Stenosemus) substriatus Kaas & Van Belle, 1990 and Ischnochiton (Ischnochiton nicklesi Kaas & Van Belle, 1990. Callistochiton pachylasmae (Di Monterosato, 1878) has been found off the coast of Morocco.

  9. Chitons (Mollusca: Polyplacophora) procured by the CANCAP I-VII expeditions, 1976-86

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    Kaas, P.

    1991-01-01

    The 327 specimens of chitons captured during six out of seven CANCAP Expeditions have been examined. They belong to 26 species, including two recently described ones: Ischnochiton (Stenosemus) substriatus Kaas & Van Belle, 1990 and Ischnochiton (Ischnochiton nicklesi Kaas & Van Belle, 1990. Callisto

  10. Proteomic analysis from the mineralized radular teeth of the giant Pacific chiton, Cryptochiton stelleri (Mollusca).

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    Nemoto, Michiko; Wang, Qianqian; Li, Dongsheng; Pan, Songqin; Matsunaga, Tadashi; Kisailus, David

    2012-09-01

    The biomineralized radular teeth of chitons are known to consist of iron-based magnetic crystals, associated with the maximum hardness and stiffness of any biomineral. Based on our transmission electron microscopy analysis of partially mineralized teeth, we suggest that the organic matrix within the teeth controls the iron oxide nucleation. Thus, we used Nano-LC-MS to perform a proteomic analysis of the organic matrix in radular teeth of the chiton Cryptochiton stelleri in order to identify the proteins involved in the biomineralization process. Since the genome sequence of C. stelleri is not available, cross-species similarity searching and de novo peptide sequencing were used to screen the proteins. Our results indicate that several proteins were dominant in the mineralized part of the radular teeth, amongst which, myoglobin and a highly acidic peptide were identified as possibly involved in the biomineralization process.

  11. Polyplacophora (Mollusca) from the San Diego Formation: A remarkable assemblage of fossil chitons from the Pliocene of southern Califoria

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    Vendrasco, Michael J.; Eernisse, Douglas J.; Powell, Charles L.; Fernandez, Christine Z.

    2012-01-01

    A rich chiton assemblage consisting of more than 15,000 valves (shell plates) was collected by George P. Kanakoff (1897–1973) from Pliocene exposures of the San Diego Formation just north of the U.S./Mexican border. The assemblage includes 16 extant species, three extinct species (Callistochiton sphaerae n. sp., Lepidozona kanakoffi n. sp., and Amicula solivaga n. sp.), and three indeterminate species. The collection is dominated by the genus Callistochiton and also includes the genera Leptochiton, Oldroydia, Lepidozona, Stenoplax, Amicula, Mopalia, Placiphorella, Tonicella, Dendrochiton, and Nuttallina. This assemblage expands the known stratigraphic and paleogeographic ranges of many chiton genera and species and provides information about an apparent late Cenozoic diversification of chitons along the Pacific Coast of North America. Chitons appear to have diversified in the northeastern Pacific from the middle Miocene to Pleistocene, driven in part by regional increases in productivity and environmental heterogeneity during that time. The chitons are interpreted to have been deposited at inner-neritic depths (,25 m) in the mouth of a bay or in a continental shelf environment, and the annual temperature range and seasonality are inferred to have been similar to those that occur off the nearby San Diego coast today. However, the fossil assemblages also include a mixture of taxa that today range only to the north or to the south. The large sample sizes of chiton valves allow rigorous analysis of the ratio of valve types, revealing a divergence from the expected pattern. This divergence is even greater on average than what occurs in assemblages of chiton valves in Holocene sediments, revealing that

  12. Nano-magnetic material in the radula teeth of chiton Acan-thochiton rubrolinestus Lischke

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    In this note, relationships among the components, structure distribution and easy magnetization direction, structure of magnetic domain of nano-magnetic material in the major mature lateral radula teeth of chiton A.rubrolinestus Lischke are probed by using the high resolution transmission electron microscope (HRTEM), the scanning electron microscope (SEM), the magnetic force microscope (MFM) and the super-conducting quantum interference device (SQUID) magnetometer from the point of view of magnetism to provide a basis for comprehending biologic function of the magnetic radula.``

  13. A preliminary study of iron isotope fractionation in marine invertebrates (chitons, Mollusca) in near-shore environments

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    Emmanuel, S.; Schuessler, J. A.; Vinther, J.; Matthews, A.; von Blanckenburg, F.

    2014-10-01

    Chitons (Mollusca) are marine invertebrates that produce radulae (teeth or rasping tongues) containing high concentrations of biomineralized magnetite and other iron-bearing minerals. As Fe isotope signatures are influenced by redox processes and biological fractionation, Fe isotopes in chiton radulae might be expected to provide an effective tracer of ambient oceanic conditions and biogeochemical cycling. Here, in a pilot study to measure Fe isotopes in marine invertebrates, we examine Fe isotopes in modern marine chiton radulae collected from different locations in the Atlantic and Pacific oceans to assess the range of isotopic values, and to test whether or not the isotopic signatures reflect seawater values. Values of δ56Fe (relative to IRMM-014) in chiton teeth range from -1.90 to 0.00 ‰ (±0.05‰ (2σ) uncertainty in δ56Fe), probably reflecting a combination of geographical control and biological fractionation processes. Comparison with published local surface seawater Fe isotope data shows a consistent negative offset of chiton teeth Fe isotope compositions relative to seawater. Strikingly, two different species from the same locality in the North Pacific (Puget Sound, Washington, USA) have distinct isotopic signatures. Tonicella lineata, which feeds on red algae in the sublittoral zone, has a mean δ56Fe of -0.65 ± 0.26‰ (2σ, 3 specimens), while Mopalia muscosa, which feeds on both green and red algae in the eulittoral zone, shows lighter isotopic values with a mean δ56Fe of -1.47 ± 0.98‰ (2σ, 5 specimens). Three possible pathways are proposed to account for the different isotopic signatures: (i) physiologically controlled processes within the chitons that lead to species-dependent fractionation; (ii) diet-controlled variability due to different Fe isotope fractionation in the red and green algal food sources; and (iii) environmentally controlled fractionation that causes variation in the isotopic signatures of bioavailable Fe in the different

  14. Analysis of an ultra hard magnetic biomineral in chiton radular teeth

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    James C. Weaver

    2010-01-01

    Full Text Available Recent analyses of the ultrastructural and mechanical properties of mineralized biological materials have demonstrated some common architectural features that can help explain their observed damage tolerance. Nature has accomplished this feat through the precise control of anisotropic crystal nucleation and growth processes in conjunction with nanoscale control over the self-assembly of spatially distinct organic and inorganic phases, resulting in effective inhibition of crack propagation through these materials. One such example is found in the hyper-mineralized and abrasion resistant radular teeth of the chitons, a group of herbivorous marine mollusks who have the surprising capacity to erode away the rocky substrates on which they graze1–4. Through the use of modern microscopy and nanomechanical characterization techniques, we describe the architectural and mechanical properties of the radular teeth from Cryptochiton stelleri. Chiton teeth are shown to exhibit the largest hardness and stiffness of any biominerals reported to date, being notably as much as three-fold harder than human enamel and the calcium carbonate-based shells of mollusks. We explain how the unique multi-phasic design of these materials contributes not only to their functionality, but also highlights some interesting design principles that might be applied to the fabrication of synthetic composites.

  15. Fine structure and immunocytochemistry of a new chemosensory system in the Chiton larva (Mollusca: Polyplacophora)

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    Haszprunar, Gerhard; Friedrich, Stefan; Wanninger, Andreas;

    2002-01-01

    Combined electron microscopy and immunocytochemistry of the larvae of several polyplacophoran species (Chiton olivaceus, Lepidochitona aff. corrugata, Mopalia muscosa) revealed a sensory system new to science, a so-called "ampullary system." The cells of the "ampullary system" are arranged in four...... symmetrically situated pairs lying dorsolaterally and ventrolaterally in the pretrochal part of the trochophore-like larva and they send axons into the cerebral commissure. They are lost at metamorphosis. The fine structure of these cells strongly resembles that of so-called "ampullary cells" known from various...... sensory organs of other molluscs, such as the apical complex of gastropod and bivalve larvae, osphradia of vetigastropods, and olfactory organs of cephalopods, and nuchal organs of certain polychaetes. The ampullary cells and their nerves are densely stained by anti-FMRF-amide fluorescence dyes, whereas...

  16. Fine structure of the mineralized teeth of the chiton Acanthopleura echinata (Mollusca: Polyplacophora).

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    Wealthall, Rosamund J; Brooker, Lesley R; Macey, David J; Griffin, Brendan J

    2005-08-01

    The major lateral teeth of the chiton Acanthopleura echinata are composite structures composed of three distinct mineral zones: a posterior layer of magnetite; a thin band of lepidocrocite just anterior to this; and apatite throughout the core and anterior regions of the cusp. Biomineralization in these teeth is a matrix-mediated process, in which the minerals are deposited around fibers, with the different biominerals described as occupying architecturally discrete compartments. In this study, a range of scanning electron microscopes was utilized to undertake a detailed in situ investigation of the fine structure of the major lateral teeth. The arrangement of the organic and biomineral components of the tooth is similar throughout the three zones, having no discrete borders between them, and with crystallites of each mineral phase extending into the adjacent mineral zone. Along the posterior surface of the tooth, the organic fibers are arranged in a series of fine parallel lines, but just within the periphery their appearance takes on a "fish scale"-like pattern, reflective of the cross section of a series of units that are overlaid, and offset from each other, in adjacent rows. The units are approximately 2 microm wide and 0.6 microm thick and comprise biomineral plates separated by organic fibers. Two types of subunits make up each "fish scale": one is elongate and curved and forms a trough, in which the other, rod-like unit, is nestled. Adjacent rod and trough units are aligned into large sheets that define the fracture plane of the tooth. The alignment of the plates of rod-trough units is complex and exhibits extreme spatial variation within the tooth cusp. Close to the posterior surface the plates are essentially horizontal and lie in a lateromedial plane, while anteriorly they are almost vertical and lie in the posteroanterior plane. An understanding of the fine structure of the mineralized teeth of chitons, and of the relationship between the organic and

  17. Diversidad de diatomeas en la dieta in situ de Chiton virgulatus (Mollusca: Polyplacophora) de Baja California Sur, México

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    David A. Siqueiros Beltrones; Uri Argumedo Hernández

    2012-01-01

    En Bahía de La Paz, Baja California Sur, se han registrado quince especies de quitones pero, en general, se descono- cen sus aspectos ecológicos básicos. Son principalmente herbívoros y observaciones preliminares sugieren que las diatomeas forman parte esencial de su alimentación por lo que el objetivo de este estudio fue determinar la diversidad de especies de diatomeas que son consumidas por Chiton virgulatus Sowerby, 1840 y si exhiben algún tipo de prefe- rencia alimentaria. Para ello se r...

  18. Middle Miocene chitons (Polyplacophora from the Slovak part of the Vienna Basin and the Danube Basin (Central Paratethys

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    Ruman Andrej

    2015-12-01

    Full Text Available We describe species-rich chiton assemblages from the Middle Miocene of the Slovak part of the Vienna Basin and the Danube Basin (Central Paratethys. They were found at five localities, including Devínska Nová Ves brickyard, Devínska Nová Ves-Útočnica, Rohožník clay pit, Kúty-45 borehole and Dubová. Thirteen species belong to eight genera from the families Leptochitonidae, Hanleyidae, Callochitonidae, Chitonidae, Tonicellidae and Acanthochitonidae. They occur predominantly in redeposited, moderately-sorted rhodolith-rich or well-sorted bioclastic layers of the Late Badenian age, and belong to lineages that presently inhabit warm-temperate and tropical regions.

  19. Shallow and deep-sea chitons of the genus Leptochiton Gray, 1847 (Mollusca: Polyplacophora: Lepidopleurida) from Peruvian and Chilean waters.

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    Sirenko, Boris

    2015-10-22

    The Southeast region off Chile and Peru has yielded a very rich diverse fauna of basal chitons of the genus Leptochiton. The present contribution is based on the study of 1055 specimens of chitons. Thirteen leptochitonid species are reported of which seven species are new, namely Leptochiton lascrusesi n. sp., L. linseae n. sp., L. longibranchiae n. sp., L. peruvianus n. sp., L. macleani n. sp., L. sigwartae n. sp., and L. mutschkeae n. sp. Five species were found on the shelf, but only one of those is limited to this zone. The other eight species live in bathyal or abyssal depths. Thus, 12 of 13 species were found deeper than 200 m. The genus Leptochiton originated in the late Palaeozoic in shallow waters. It probably shifted to deep-waters because of competition by more advanced genera of chitons. The leptochitonid fauna of the Peru-Chile Trench turned out to be rich. Five species were studied from this trench system. Two of them-L. longibranchiae n. sp. and L. peruvianus n. sp.-are characterized by an unusually high number of gills and an accordingly wider distribution in the mantle cavity, reaching in an anterior direction to valves V and III. This morphological peculiarity is unusual for Lepidopleurida and resembles the conditions found in the order Chitonida.

  20. Emergence, development, and maturity of the gonad of two species of chitons "sea cockroach" (Mollusca: Polyplacophora through the early life stages.

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    Omar Hernando Avila-Poveda

    Full Text Available This study describes and recognises, using histological and microscopical examinations on a morphometrical basis, several gonad traits through the early life stages of Chiton articulatus and C. albolineatus. Gonadal ontogenesis, gonad development stages, sexual differentiation, onset of the first sexual maturity, and growth sequences or "early life stages" were determined. In addition, allometry between lengths and body weight pooled for both sexes per each chiton were calculated using equation Y = aX(b . A total of 125 chitons (4≤TL≤40 mm, in total length "TL" were used. All allometric relations showed a strong positive correlation (r, close to 1, with b-values above three, indicating an isometric growth. Gonadal ontogenesis and gonad development stages were categorised into three periods ("Pw" without gonad, "Pe" gonad emergence, and "Pf" gonadal sac formed and four stages ("S0" gametocytogenesis, "S1" gametogenesis, "S2" mature, and "S3" spawning, respectively. Compound digital images were attained for each process. Periods and stages are overlapped among them and between species, with the following overall confidence intervals in TL: Pw 6.13-14.32 mm, Pe 10.32-16.93 mm, Pf 12.99-25.01 mm, S0 16.08-24.34 mm (females and 19.51-26.60 mm (males, S1 27.15-35.63 mm (females and 23.45-32.27 mm (males, S2 24.48-40.24 mm (females and 25.45-32.87 mm (males. Sexual differentiation (in S0 of both chitons occurs first as a female then as a male; although, males reach the onset of the first sexual maturity earlier than females, thus for C. articulatus males at 17 mm and females at 32 mm, and for C. albolineatus males at 23.5 mm and females at 28 mm, all in TL. Four early life stages (i.e., subjuvenile, juvenile, subadult, and adult are described and proposed to distinguish growth sequences. Our results may be useful to diverse disciplines, from developmental biology to fisheries management.

  1. Estructura poblacional de Chiton articulatus en las islas Pájaros y Venados de la bahía de Mazatlán, Sinaloa, México Population structure of Chiton articulatus from Pájaros and Venados islands of Mazatlán Bay, Sinaloa, Mexico

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    Luis Miguel Flores-Campaña

    2007-10-01

    Full Text Available El propósito del presente trabajo fue contribuir al conocimiento biológico y pesquero de Chiton articulatus, especie que se captura artesanalmente en las costas de Mazatlán, Sinaloa. Se realizaron recolectas bimestrales en la zona intermareal de las islas Pájaros y Venados, de febrero a diciembre de 2000, durante las mareas más bajas. Las recolectas se realizaron en 4 sitios distintos, 2 en la zona protegida frente a la bahía Mazatlán y 2 en la zona expuesta de ambas islas; los ejemplares se trasladaron al laboratorio para su identificación y registro de dimensiones corporales con un vernier (±0.1 mm y una balanza (± 0.001g. Se analizaron 1 236 organismos, su longitud total (Lt osciló entre 11.2 y 86.8 mm, su altura (Al fue de 2.0 a 48.1 mm, su anchura (An varió de 7.1 mm a 48.1 mm y su peso total (Pt entre 0.1 y 53.8 g. La mayor parte de la población se distribuyó entre los 31 y 64 mm, con una moda de 41.1 mm y media de 45.6±8.5 mm de Lt. En la zona expuesta de isla Pájaros se presentaron mayores tallas, mientras que las menores se encontraron en la zona protegida de isla Venados; esta diferencia puede explicarse tanto por el grado de exposición al oleaje como por la presión de pesca, que se relaciona con la dificultad de acceso en cada zona. Las relaciones biométricas entre las tallas fueron de tipo lineal {An=0.5423(Lt+2.7594, Al=0.2316(Lt-0.4576 y Al=0.3807(An-0.3832} y entre talla y peso fueron de tipo potencial {Pt=0.0001(Lt2.8404, Pt=0.0005(An2.8807 y Pt=0.0329(Al2.3236}; los valores de la pendiente (b de las relaciones entre la talla y el peso fueron cercanos a 3, por lo cual se considera que su crecimiento es de tipo isométrico. La relación entre el Pt y el peso del pie (Pp fue {Pt=4.8778(Pp+1.0933}. La proporción que se aprovecha de cada individuo es casi del 17 % de su Pt. La captura de C. articulatus es una actividad de subsistencia que diversos grupos realizan de manera temporal o complementaria de otras

  2. Trophic ecology of the chiton Acanthopleura echinata on Chilean rocky shores Ecología trófica del chitón Acanthopleura echinata en costas rocosas de Chile

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    PATRICIO A CAMUS

    2012-03-01

    Full Text Available Polyplacophorans are common herbivores on rocky shores, but basic aspects of their ecology remain scarcely studied and their role within communities could be more complex than previously considered. Such is the case of Acanthopleura echinata (Barnes, one of the largest and most conspicuous chitons in the world, and at the same time, one of the least known intertidal species in the southeastern Pacific. To improve the basic ecological knowledge of this potentially important intertidal consumer, we studied the diet of A. echinata and its variation among sites of varying levels of coastal upwelling spread over 1000 km along the coast of northern Chile. A seasonal evaluation of diet, body size distribution and density at sites expected to vary in overall nutrient loadings, benthic algal productivity and sea surface temperature, allowed us to examine plasticity in Acantholeura diet and body size. Overall, A. echinata consumed 85 items of algae (64.7 %, mainly fleshy and calcified encrusting thalli and invertebrates (35.3 %, mainly barnacles. Diet was always dominated by encrusting corallines, although the proportion of algae increased with body size suggesting an ontogenetic variation in feeding habits. Although the number and occurrence frequency of dietary items varied significantly in time and space, there were no consistent seasonal patterns and the dominant items in the diet remained the same at all places. The density of A. echinata showed no significant spatial variation, but its body size and diet breadth correlated positively among sites and both tended to increase with latitude. Our results show that A. echinata is a generalist, polyphagous consumer with a high potential for affecting the space-occupancy dynamics in the intertidal system, and also that among site variation in diet bears no simple relationship with variation in sea surface temperature and upwelling intensity.Los poliplacóforos son herbívoros comunes en costas rocosas, pero

  3. Interspecific competition for shelters in territorial and gregarious intertidal grazers: consequences for individual behaviour.

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    Aguilera, Moisés A; Navarrete, Sergio A

    2012-01-01

    Experiments have shown that interspecific interactions within consumer guilds can alter patterns of distribution, abundance and size of species. Plastic behavioural responses can be modulated by agonistic interactions. In many cases, consumers compete for space and shelters, and these interactions change the manner in which they exploit food. This study investigates the consequences of competition in the spatial and temporal organization of behaviour of intertidal grazers, which share algal resources and the use of rock crevices while resting, but exhibit different body sizes, spatial behaviour and foraging modes. We evaluate interaction strength between small gregarious Siphonaria lessoni and the larger territorial keyhole limpet Fissurella crassa and between S. lessoni and the medium-size gregarious chiton Chiton granosus. Using field manipulations and artificial arenas in the laboratory, we tested whether the use of crevices, micro-spatial distribution and activity are modified by the density of conspecifics and the presence of heterospecifics. Our results show that small-scale spatial segregation observed in the field between S. lessoni and C. granosus result from species-specific differences in habitat use. In turn, we found evidence that spatial segregation between F. crassa and S. lessoni results from highly asymmetric interference competition in the use of shelters. The presence of F. crassa reduced the use of crevices and growth rates of S. lessoni. Effects on growth rates are assumed to result from exposure to harsh environmental conditions rather than food limitation. Thus, neither gregarious behaviour nor differences in activity were sufficient to prevent competition with the larger grazer. Our study illustrates the importance of competition for shelters, which results in behavioural changes of the smaller-sized species, and how these plastic responses can translate into differences in growth rates. Use of shelters can thus be modulated by environmental

  4. Interspecific competition for shelters in territorial and gregarious intertidal grazers: consequences for individual behaviour.

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    Moisés A Aguilera

    Full Text Available Experiments have shown that interspecific interactions within consumer guilds can alter patterns of distribution, abundance and size of species. Plastic behavioural responses can be modulated by agonistic interactions. In many cases, consumers compete for space and shelters, and these interactions change the manner in which they exploit food. This study investigates the consequences of competition in the spatial and temporal organization of behaviour of intertidal grazers, which share algal resources and the use of rock crevices while resting, but exhibit different body sizes, spatial behaviour and foraging modes. We evaluate interaction strength between small gregarious Siphonaria lessoni and the larger territorial keyhole limpet Fissurella crassa and between S. lessoni and the medium-size gregarious chiton Chiton granosus. Using field manipulations and artificial arenas in the laboratory, we tested whether the use of crevices, micro-spatial distribution and activity are modified by the density of conspecifics and the presence of heterospecifics. Our results show that small-scale spatial segregation observed in the field between S. lessoni and C. granosus result from species-specific differences in habitat use. In turn, we found evidence that spatial segregation between F. crassa and S. lessoni results from highly asymmetric interference competition in the use of shelters. The presence of F. crassa reduced the use of crevices and growth rates of S. lessoni. Effects on growth rates are assumed to result from exposure to harsh environmental conditions rather than food limitation. Thus, neither gregarious behaviour nor differences in activity were sufficient to prevent competition with the larger grazer. Our study illustrates the importance of competition for shelters, which results in behavioural changes of the smaller-sized species, and how these plastic responses can translate into differences in growth rates. Use of shelters can thus be

  5. Consumption and digestion of animal food by rocky intertidal herbivores: an evaluation of digestive flexibility and omnivory in three grazing species Consumo y digestión de alimento animal por herbívoros del intermareal rocoso: evaluación de flexibilidad digestiva y omnivoría en tres especies de pastoreadores

    Directory of Open Access Journals (Sweden)

    Patricio A Camus

    2009-01-01

    Full Text Available The ingestion of invertebrates by herbivores on rocky intertidal shores is traditionally considered a casual phenomenon. However, a recent study of 29 species in northern Chile shows that animal consumption is widespread, consistent, and important, suggesting that some of these herbivores may actually be omnivores. Therefore, we examined the capability of three common Chilean herbivores (the key-hole limpets Fissurella limbata and Fissurella pida and the polyplacophoran Chiton granosus to digest animal food. For each species, we conducted no-choice feeding experiments using artificial foods based on either algal or animal tissue from one of their frequent prey (Ulva rigida, Perumytilus purpuratus. After the feeding trials, we evaluated the total proteolytic activity (availability of free amino acids in the digestive contents of the species studied and, as a reference, we evaluated this activity in animals obtained directly from the field. We found that all three species were able to eat animal food, and this consumption was not significantly different from that of algal food, suggesting that both foods were not only edible but at least similarly palatable. In addition, we detected comparable levels of proteolytic activity under the three feeding conditions for the three species. No statistical differences were found for C. granosus, but activity was significantly higher with animal food in F. limbata and with algal food in F. pida. Our data show the high digestive flexibility of these species, suggesting their ability for adaptive modulation and the possibility that they are true omnivorous consumers. We discuss the implications of these results for our current view of the structure of rocky intertidal food webs.La ingestión de invertebrados por herbívoros de costas intermareales rocosas se considera tradi-cionalmente un fenómeno casual. Sin embargo, un estudio reciente en 29 especies del norte de Chile muestra que el consumo animal es

  6. First record of a chiton from the Palaeocene of Denmark (Polyplacophora: Leptochitonidae) and its phylogenetic affinities

    DEFF Research Database (Denmark)

    Sigwart, Julia D.; Andersen, Søren Bo; Schnetler, K. Ingemann

    2007-01-01

    Den første rapport om en skallus fra Fakse Kalkbrud, i løs koralkalk fra Mellem Danien. Det er samtidig opstillingen af en ny art, Leptochiton faksensis. En cladistisk analyse udføres med flere end 100 recente og fossile arter af ordenen Lepidopleurida. Palæoøkologisk udsiger denne arts forekomst...

  7. New records for the shallow-water chiton fauna (Mollusca, Polyplacophora of the Azores (NE Atlantic

    Directory of Open Access Journals (Sweden)

    Sérgio Ávila

    2013-06-01

    Full Text Available Published records, original data from recent field work on all of the islands of the Azores (NE Atlantic, and a revision of the entire mollusc collection deposited in the Department of Biology of the University of the Azores (DBUA were used to compile a checklist of the shallow-water Polyplacophora of the Azores. Lepidochitona cf. canariensis and Tonicella rubra are reported for the first time for this archipelago, increasing the recorded Azorean fauna to seven species.

  8. Moluscos Poliplacóforos del litoral atlántico del sur de la Península Ibérica

    Directory of Open Access Journals (Sweden)

    Carmona Zalvide, M. P.

    2000-12-01

    Full Text Available In this paper, an updated check-list of the polyplacophoran species from Sagres (Portugal to Strait of Gibraltar is present. Twenty taxa are recorded in this area: Lepidopleurus cajetanus, Leptochiton cancellatus, Leptochiton algesirensis, Leptochiton scabridus, Callochiton septemvalvis, Callochiton euplaeae, Lepidochitona cinerea, Lepidochitona corrugata, Lepidochitona canariensis, Lepidochitona monterosatoi, Lepidochitona kaasi, Lepidochitona severianoi, Chaetopleura angulata, Ischnochiton rissoi, Chiton olivaceus, Chiton corallinus, Chiton phaesolinus, Acanthochitona fascicularis and Acanthochitona crinita. From these species, Lepidochitona canariensis, L simrothi, Callochiton septemvalvis and Lepidochitona monterosatoi amplify their geographical distribution to Southern Atlantic coast of southern Iberian Peninsula.

    Se aporta el catálogo de los Moluscos Poliplacóforos de las costas atlánticas del sur de la Península Ibérica, desde Sagres (Portugal hasta Gibraltar. Se cita un total de 20 taxones (Lepidopleurus cajetanus, Leptochiton cancellatus, Leptochiton algesirensis, Leptochiton scabridus, Callochiton septemvalvis, Callochiton euplaeae, Lepidochitona cinerea, Lepidochitona corrugata, Lepidochitona canariensis, Lepidochitona monterosatoi, Lepidochitona kaasi, Lepidochitona severianoi, Chaetopleura angulata, Ischnochiton rissoi, Chiton olivaceus, Chiton corallinus, Chiton phaesolinus, Acanthochitona fascicularis y Acanthochitona crinita todos ellos pertenecientes al dominio litoral. La captura de Lepidochitona canariensis y L. simrothi en aguas atlánticas ibéricas constituye la primera cita para el suratlántico ibérico. A su vez se amplía la distribución a esta zona de Callochiton septemvalvis y de Lepidochitona monterosatoi.

  9. Iron isotope fractionation in marine invertebrates in near shore environments

    Science.gov (United States)

    Emmanuel, S.; Schuessler, J. A.; Vinther, J.; Matthews, A.; von Blanckenburg, F.

    2014-04-01

    Chitons (Mollusca) are marine invertebrates that produce radula (teeth or rasping tongue) containing high concentrations of biomineralized magnetite and other iron bearing minerals. As Fe isotope signatures are influenced by redox processes and biological fractionation, Fe isotopes in chiton radula might be expected to provide an effective tracer of ambient oceanic conditions and biogeochemical cycling. Here, in a pilot study to measure Fe isotopes in marine invertebrates, we examine Fe isotopes in modern marine chiton radula collected from different locations in the Atlantic and Pacific oceans to assess the range of isotopic values, and to test whether or not the isotopic signatures reflect seawater values. Furthermore, by comparing two species that have very different feeding habits but collected from the same location, we infer a possible link between diet and Fe isotopic signatures. Values of δ56Fe (relative to IRMM-014) in chiton teeth range from -1.90 to 0.00‰ (±0.05‰ (2σ) uncertainty in δ56Fe), probably reflecting a combination of geographical control and biological fractionation processes. Comparison with published local surface seawater Fe isotope data shows a consistent negative offset of chiton teeth Fe isotope compositions relative to seawater. Strikingly, two different species from the same locality in the North Pacific (Puget Sound, Washington, USA) have distinct isotopic signatures. Tonicella lineata, which feeds on red algae, has a mean δ56Fe of -0.65 ± 0.26‰ (2σ, 3 specimens), while Mopalia muscosa, which feeds primarily on green algae, shows lighter isotopic values with a mean δ56Fe of -1.47 ± 0.98‰ (2σ, 5 specimens). Although chitons are not simple recorders of the ambient seawater Fe isotopic signature, these preliminary results suggest that Fe isotopes provide information concerning Fe biogeochemical cycling in near shore environments, and might be used to probe sources of Fe in the diets of different organisms.

  10. Is the Schwabe Organ a Retained Larval Eye? Anatomical and Behavioural Studies of a Novel Sense Organ in Adult Leptochiton asellus (Mollusca, Polyplacophora) Indicate Links to Larval Photoreceptors.

    Science.gov (United States)

    Sumner-Rooney, Lauren H; Sigwart, Julia D

    2015-01-01

    The discovery of a sensory organ, the Schwabe organ, was recently reported as a unifying feature of chitons in the order Lepidopleurida. It is a patch of pigmented tissue located on the roof of the pallial cavity, beneath the velum on either side of the mouth. The epithelium is densely innervated and contains two types of potential sensory cells. As the function of the Schwabe organ remains unknown, we have taken a cross-disciplinary approach, using anatomical, histological and behavioural techniques to understand it. In general, the pigmentation that characterises this sensory structure gradually fades after death; however, one particular concentrated pigment dot persists. This dot is positionally homologous to the larval eye in chiton trochophores, found in the same neuroanatomical location, and furthermore the metamorphic migration of the larval eye is ventral in species known to possess Schwabe organs. Here we report the presence of a discrete subsurface epithelial structure in the region of the Schwabe organ in Leptochiton asellus that histologically resembles the chiton larval eye. Behavioural experiments demonstrate that Leptochiton asellus with intact Schwabe organs actively avoid an upwelling light source, while Leptochiton asellus with surgically ablated Schwabe organs and a control species lacking the organ (members of the other extant order, Chitonida) do not (Kruskal-Wallis, H = 24.82, df = 3, p organ represents the adult expression of the chiton larval eye, being retained and elaborated in adult lepidopleurans.

  11. Radular teeth as models for the improvement of industrial cutting devices

    NARCIS (Netherlands)

    van der Wal, P; Giesen, HJ; Videler, JJ

    2000-01-01

    Limpets (Gastropoda) and chitons (Polyplacophora) feed on epi- and endolithic organisms by means of the radula, a specialized feeding apparatus located in the mouth cavity. The radula owes most of its abrasive capability to the presence of numerous mineralized teeth. Here we report on the shape, int

  12. Ichnotaxa for bite traces of thetrapods : A new area of research or a total waste of time?

    DEFF Research Database (Denmark)

    Jacobsen, Aase Roland; Bromley, Richard Granville

    as a whole, as in Gnathichnus for echinoid bioerosion and Radulichnus for chiton and gastropod bioerosion, it is our conviction that tetrapod biting trace fossil nomenclature generally should be based on the damage caused by single teeth. Where several teeth have left traces as a group, this may...

  13. Is the Schwabe Organ a Retained Larval Eye? Anatomical and Behavioural Studies of a Novel Sense Organ in Adult Leptochiton asellus (Mollusca, Polyplacophora Indicate Links to Larval Photoreceptors.

    Directory of Open Access Journals (Sweden)

    Lauren H Sumner-Rooney

    Full Text Available The discovery of a sensory organ, the Schwabe organ, was recently reported as a unifying feature of chitons in the order Lepidopleurida. It is a patch of pigmented tissue located on the roof of the pallial cavity, beneath the velum on either side of the mouth. The epithelium is densely innervated and contains two types of potential sensory cells. As the function of the Schwabe organ remains unknown, we have taken a cross-disciplinary approach, using anatomical, histological and behavioural techniques to understand it. In general, the pigmentation that characterises this sensory structure gradually fades after death; however, one particular concentrated pigment dot persists. This dot is positionally homologous to the larval eye in chiton trochophores, found in the same neuroanatomical location, and furthermore the metamorphic migration of the larval eye is ventral in species known to possess Schwabe organs. Here we report the presence of a discrete subsurface epithelial structure in the region of the Schwabe organ in Leptochiton asellus that histologically resembles the chiton larval eye. Behavioural experiments demonstrate that Leptochiton asellus with intact Schwabe organs actively avoid an upwelling light source, while Leptochiton asellus with surgically ablated Schwabe organs and a control species lacking the organ (members of the other extant order, Chitonida do not (Kruskal-Wallis, H = 24.82, df = 3, p < 0.0001. We propose that the Schwabe organ represents the adult expression of the chiton larval eye, being retained and elaborated in adult lepidopleurans.

  14. Two newly recognized species of Hemidactylus (Squamata, Gekkonidae) from the Arabian Peninsula and Sinai, Egypt.

    Science.gov (United States)

    Smíd, Jiří; Moravec, Jiří; Kratochvíl, Lukáš; Gvoždík, Václav; Nasher, Abdul Karim; Busais, Salem M; Wilms, Thomas; Shobrak, Mohammed Y; Carranza, Salvador

    2013-01-01

    A recent molecular phylogeny of the Arid clade of the genus Hemidactylus revealed that the recently described H. saba and two unnamed Hemidactylus species from Sinai, Saudi Arabia and Yemen form a well-supported monophyletic group within the Arabian radiation of the genus. The name 'Hemidactylus saba species group' is suggested for this clade. According to the results of morphological comparisons and the molecular analyses using two mitochondrial (12S and cytb) and four nuclear (cmos, mc1r, rag1, rag2) genes, the name Hemidactylus granosus Heyden, 1827 is resurrected from the synonymy of H. turcicus for the Sinai and Saudi Arabian species. The third species of this group from Yemen is described formally as a new species H. ulii sp. n. The phylogenetic relationships of the members of 'Hemidactylus saba species group' are evaluated and the distribution and ecology of individual species are discussed.

  15. Responses of the molluscan fauna to environmental variations in a Halodule wrightii Ascherson ecosystem from Northeastern Brazil

    OpenAIRE

    BARROS,KCRISHNA V.S.; Rocha-Barreira,Cristina A

    2013-01-01

    ABSTRACT This study observed the spatial and temporal distributions of molluscs in a Halodule wrightii meadow, verifying if they respond satisfactorily to seasonal changes in this seagrass ecosystem. Twenty-four species were identified. Chitons were rare, bivalves had greater number of species (11), followed by gastropods (9) which were also the most abundant class (73%). All classes were more abundant in the belowground. The most common species was Tricolia affinis, especially in aboveground...

  16. Procurement of a Nanoindenter for Structure-Function Analyses of Biologically Inspired High Performance Composite Materials

    Science.gov (United States)

    2012-01-13

    Zavattieri (Purdue University), Dr. Ali Miserez (Nanyang University), Dr. Dimitri Deheyn (Scripps, UCSD), Dr. Masa Rao (UCR). Finally, through the...Chitons. The fourth project, to be performed in collaboration with Professor Masa Rao at UCR, would investigate micro-and nano-mechanical properties...Miserez (Nanyang University), Dr. Dimitri Deheyn (Scripps, UCSD), Dr. Masa Rao (UCR). Finally, through the procurement of this instrument, the data we

  17. Competing mechanisms in the wear resistance behavior of biomineralized rod-like microstructures

    Science.gov (United States)

    Escobar de Obaldia, Enrique; Herrera, Steven; Grunenfelder, Lessa Kay; Kisailus, David; Zavattieri, Pablo

    2016-11-01

    The remarkable mechanical properties observed in biological composite materials relative to those of their individual constituents distinguish them from common engineering materials. Some naturally occurring high-performance ceramics, like the external veneer of the Chiton (Cryptochiton stelleri) tooth, have been shown to have superior hardness and impressive abrasion resistance properties. The mechanical performance of the chiton tooth has been attributed to a hierarchical arrangement of nanostructured magnetite rods surrounded with organic material. While nanoindentation tests provide useful information about the overall performance of this biological composite, understanding the key microstructural features and energy dissipation mechanisms at small scales remains a challenging task. We present a combined experimental/numerical approach to elucidate the role of material deformation in the rods, debonding at the rod interfaces and the influence of energy dissipation mechanisms on the ability of the microstructure to distribute damage under extreme loading conditions. We employ a 3D finite element-based micromechanical model to simulate the nanoindentation tests performed in geological magnetite and cross-sections of the chiton tooth. This proposed model is capable of capturing the inelastic deformation of the rods and the failure of their interfaces, while damage, fracture and fragmentation of the mineralized rods is assessed using a probabilistic function. Our results show that these natural materials achieve their abrasion resistant properties by controlling the interface strength between rods, alleviating the tensile stress on the rods near the indentation tip and therefore decreasing the probability of catastrophic failure without significantly sacrificing resistance to penetration. The understanding of these competing energy dissipating mechanisms provides a path to the prediction of new combination of materials. In turns, these results suggest certain

  18. Concentraciones traza de metales en especies marinas de la bahía de Huarmey, Ancash, Perú

    Directory of Open Access Journals (Sweden)

    María E. Jacinto

    2013-04-01

    Full Text Available Se determinaron las concentraciones traza de cadmio, cobre, plomo y zinc, en músculos y vísceras del caracol (Stramonita T. chocolata, el cangrejo peludo (Cancer setosus, la cabrilla (Paralabrax humeralis, el chorito (Semimytilus algosus, la lapa (Fissurella sp. y el chitón (Chiton spp., indeterminado; colectados en octubre 2001 en la bahía de Huarmey, Ancash, Perú. Los órganos seleccionados fueron liofi lizados y sometidos a digestión ácida según método CEM USA 1994 y analizados por espectrofotometría de absorción atómica. Las menores concentraciones de cadmio (0,63 μg/g, cobre (1,87 μg/g y zinc (1,70 μg/g, se encontraron en el músculo de P. humeralis; mientras que valores máximos de zinc (24,16 μg/g se observaron en vísceras del T. chocolata y de cobre (28,0 μg/g en músculo de Chiton spp. Las concentraciones halladas estuvieron dentro de los límites internacionales establecidos por algunos países (Nauen, 1983.

  19. Pamphagidae (Orthoptera: Caelifera) of North Africa: key to genera and the annotated check-list of species.

    Science.gov (United States)

    Massa, Bruno

    2013-01-01

    At least 95 species of Pamphagidae belonging to 17 genera are known in North Africa. Taxonomic status is fairly known, with some exception, mainly due to scarcity of available specimens of some genera in museums and collections. In this paper, the author proposes a new key to genera and reports the annotated list of all the known species, based on specimens examined in different European museums. Concerning the subfamily Thrinchinae, he proposes to consider only the following species of the genus Tmethis: T. cisti, T. harterti new status, T. maroccanus and T. pulchripennis. He also considers Neotmethis bidentatus synonym of T. harterti, and the three newly described species of the genus Tuarega as synonyms of T. insignis. In addition, he proposes to remove Batrachotettix elephas from the synonyms of T. insignis, because its description consents to establish that it belongs to a South African Porthetinae, not to a Thrinchinae. With regard to the subfamily Pamphaginae, the author recognizes the presence in North Africa of three tribes, until now containing 90 species: Finotiini, Pamphagini and Euryparyphini; Amigus is definitively considered a valid genus within the tribe Pamphagini, with the only species A. nigroadspersus. Additionally, he proposes a new key to species of the genus Paracinipe. He considers Paracinipe theryi as a valid species; previously it has been listed as subspecies of P. dolichocera. He also establishes that Acinipe calabra of Italy is the same taxon living in North Africa. Further, he describes Euryparyphes rungsi new species from Middle Atlas, and Paraeumigus lopezi new species from West Morocco, and synonymizes Eunapiodes granosus rungsi with E. atlantis. Finally, he reports biometric data of the genera Tmethis, Paracinipe, Paraeumigus and Eunapiodes.

  20. Overview of the amorphous precursor phase strategy in biomineralization

    Institute of Scientific and Technical Information of China (English)

    Steve WEINER; Julia MAHAMID; Yael POLITI; Yurong MA; Lia ADDADI

    2009-01-01

    It was assumed for a long time that organisms produce minerals directly from a saturated solution. A few exceptions were known,including the well documented mineralized teeth of the chiton. In 1997 it was demon-stratedthat sea urchin larvae form their calcitic spicules by first depositing a highly unstable mineral phase called amorphous cualcium carbonate.This other phgyla has since been shown to be used by anlmals from other phyla and for both aragonita and calcite Recent evidence shows that vertebrate bone mineral may also be formed via a precursor phase of amorphous calcium carbonate. This strategy thus appears to be widespread The challenge now is to understand the mechanisms by which these unstable phases are initially formed,how they are temporarily stabilized and how they are destabilized and trans form into a crystalline mature product.

  1. Application of the X-ray analyses on bioaccumulation and biomineralization for the specific elements

    Energy Technology Data Exchange (ETDEWEB)

    Numako, Chiya [Tokushima Univ., Faculty of Integrated Arts and Sciences, Tokushima (Japan)

    2003-03-01

    Specific accumulation of the elements by biological activity has a large influence on a material recycling on the earth. Some non-distractive characterizations by X-ray spectroscopy, XRF and/or XAFS measurements with synchrotron radiation have been applied to some solid state specimens which accumulate heavy metals at high concentration in order to elucidate its mechanism or purpose of the phenomena for each marine creature. It has been known that a few bivalves including giant clams stock kidney granules that accumulate Mn and Zn specifically. The results of two-dimensional elemental analyses by EPMA indicate zoning structures of the concentration of Mn, Zn and Mg negative correlation between Mg and (Mn + Zn) inside of a granule. Fluorescence XAFS analyses for Mn and Zn in the kidney granules, held at BL-7C, PF, KEK, shows that Mn and Zn exist as divalent cations in amorphous calcium phosphate matrix. It is considered that Mn and Zn have got a detoxication by substitution for Mg into amorphous calcium phosphate with flexible crystal structure. The teeth of chiton, which accumulate magnetite as a major substance of the teeth, have been also studied by SR-XRF and micro XAFS technique with microbeam focused in 6 {mu}m {phi} from undulator at SPring-8, BL-39XU. In the early stage of the teeth formation, abrupt accumulation of Fe into a feeding plane of a tooth, while the concentration of Ca has been remained equally at the back of a tooth. Micro-XAFS measurement for Fe in the teeth indicates that a major material of the feeding plane is magnetite while trivalent iron compounds appears along the junction zone of the tooth and a base membrane. There is a complex scheme in the tooth formation of chiton, which is available to create some kinds of iron species and allocates those into different positions in a tooth. (author)

  2. From grazing marks to collapsed cliffs - intertidal bioerosion on all scales

    Science.gov (United States)

    Kázmér, Miklós; Taboroši, Danko; Hsieh, Meng-Long; Shafeea Leman, Mohd; Aziz Ali, Che; Roslan Mohamed, Kamal; Choowong, Montri

    2014-05-01

    Rocky shores - particularly in limestone areas of tropical, subtropical, and some temperate regions - are subject to intense bioerosion. Detailed field studies along the Gulf of Siam and the Andaman coast of Thailand, Langkawi Islands of Malaysia, southern Java and Bali in Indonesia, Palau Islands, and Okinawa revealed the presence of rich populations of bioeroding organisms in the intertidal zone. Molluscs capable of damaging rock (the chiton Acanthopleura, limpets, and whelks) leave grazing traces as they feed on bacterial and algal biofilms and chasmolithic and endolithic microorganisms. Boring sponges (Entobia), bivalves (Gastrochaenolites and others), boring sipunculid worms (Caulostrepsis), and sea urchins (Echinometra) drill deeper to hide from predators beneath the rock surface. Individually, members of these taxa leave marks ranging from sub-millimetre to the metre scale, but collectively, their erosion creates marine notches, several-metres-deep features extending between low and high tide marks. When cliffs overhanging these notches collapse, landscape-scale scars are left behind. The various bioeroders display a clear vertical zonation between low and high tide. These are dictated by environmental stress, food availability, competition, and predation. Typical inhabitants of present-day zones include - from top to bottom - littorinid snails, patellid limpets, chitons, boring bivalves, and boring sea urchins. Each organism leaves a characteristic mark in the bedrock. Trace fossils found in the 'wrong place' - either too high or too low compared to the present-day occurrence of the animals - suggest changes in relative sea level. Similarly, sea level changes are suggested by the presence of compound markings produced through overprinting by organisms that live in different ecological zones. Preservation and obliteration of traces depends on the rates of sea level change and coastal denudation. Morphology of bioerosional markings and their vertical zonation

  3. Magnetite Biomineralization: Fifty years of progress, from beach-combing to the SQUID microscope

    Science.gov (United States)

    Kirschvink, J. L.; Dixson, A. D.; Raub, T.

    2012-12-01

    Magnetite biomineralization was first discovered 50 years ago as a hardening agent in the teeth of the Polyplacophoran molluscs (chitons) by the late Prof. Heinz A. Lowenstam of Caltech, when he noticed unusual erosional effects produced by their grazing in the intertidal zones of Palau (Lowenstam, 1962). Since then, biogenic magnetite has been detected in a broad range of organisms, including magnetotactic bacteria, protists, insects, fish, amphibians, reptiles, birds, and mammals including humans. In many species, the role of ferromagnetic material as a neurophysiological transducer is demonstrated clearly through the effects of pulse-remagnetization on behavior. A brief (1 uS), properly configured magnetic discharge from a rectified LC circuit, tailored to exceed the coercivity of the magnetite, will often abolish a magnetic behavioral response, or in some cases make the organism go the wrong way. This is a unique ferromagnetic effect. The genes controlling magnetite biomineralization are well characterized in several species of bacteria, and the ability of some of these bacterial genes to initiate magnetite precipitation in mammalian cell lines argues for a common descent, probably via a magnetotactic mitochondrial ancestor. Previous studies in fish reported the presence of single-domain magnetite crystals in cells near projections of the trigeminal nerve, co-located in the olfactory epithelium. Although the cells are rare, the recent development of a spinning magnetic field technique allows easy identification and isolation of these cells for individual study (Eder et al., 2012). The cells are surprisingly magnetic, with moments hundreds of times larger than typical magnetotactic bacteria. Subsequent efforts to identify the anatomical seat of magnetoreceptors have focused on the same locations in new organisms, excluding other areas. Using SQUID moment magnetometry and SQUID scanning microscopy, we report here the unexpected presence of biogenic magnetite in

  4. Responses of the molluscan fauna to environmental variations in a Halodule wrightii Ascherson ecosystem from Northeastern Brazil

    Directory of Open Access Journals (Sweden)

    KCRISHNA V.S. BARROS

    2013-10-01

    Full Text Available ABSTRACT This study observed the spatial and temporal distributions of molluscs in a Halodule wrightii meadow, verifying if they respond satisfactorily to seasonal changes in this seagrass ecosystem. Twenty-four species were identified. Chitons were rare, bivalves had greater number of species (11, followed by gastropods (9 which were also the most abundant class (73%. All classes were more abundant in the belowground. The most common species was Tricolia affinis, especially in aboveground. The occurrence of some species in both strata or out of the expected stratum may have been influenced by shallow layer of the sediment considered in this study, hydrodynamic, and low biomass of the studied meadow. According to univariate and multivariate analyses, despite of molluscan descriptors had been related to variables associated with rainfall, the seagrasses had an important role on the seasonal and vertical variations of the molluscan fauna. The biomass of the epiphyte Hypnea musciformis was correlated to temporal variations of the species from aboveground, indicating its secondary role for this community. The molluscs were sensible to environmental variations, and also reflected seasonal changes of the seagrass, showing that damages on these meadows reflect even at lower levels of the marine food web.

  5. Responses of the molluscan fauna to environmental variations in a Halodule wrightii Ascherson ecosystem from Northeastern Brazil.

    Science.gov (United States)

    Barros, Kcrishna V S; Rocha-Barreira, Cristina A

    2013-01-01

    This study observed the spatial and temporal distributions of molluscs in a Halodule wrightii meadow, verifying if they respond satisfactorily to seasonal changes in this seagrass ecosystem. Twenty-four species were identified. Chitons were rare, bivalves had greater number of species (11), followed by gastropods (9) which were also the most abundant class (73%). All classes were more abundant in the belowground. The most common species was Tricolia affinis, especially in aboveground. The occurrence of some species in both strata or out of the expected stratum may have been influenced by shallow layer of the sediment considered in this study, hydrodynamic, and low biomass of the studied meadow. According to univariate and multivariate analyses, despite of molluscan descriptors had been related to variables associated with rainfall, the seagrasses had an important role on the seasonal and vertical variations of the molluscan fauna. The biomass of the epiphyte Hypnea musciformis was correlated to temporal variations of the species from aboveground, indicating its secondary role for this community. The molluscs were sensible to environmental variations, and also reflected seasonal changes of the seagrass, showing that damages on these meadows reflect even at lower levels of the marine food web.

  6. The continuing debate on deep molluscan phylogeny: evidence for Serialia (Mollusca, Monoplacophora + Polyplacophora).

    Science.gov (United States)

    Stöger, I; Sigwart, J D; Kano, Y; Knebelsberger, T; Marshall, B A; Schwabe, E; Schrödl, M

    2013-01-01

    Molluscs are a diverse animal phylum with a formidable fossil record. Although there is little doubt about the monophyly of the eight extant classes, relationships between these groups are controversial. We analysed a comprehensive multilocus molecular data set for molluscs, the first to include multiple species from all classes, including five monoplacophorans in both extant families. Our analyses of five markers resolve two major clades: the first includes gastropods and bivalves sister to Serialia (monoplacophorans and chitons), and the second comprises scaphopods sister to aplacophorans and cephalopods. Traditional groupings such as Testaria, Aculifera, and Conchifera are rejected by our data with significant Approximately Unbiased (AU) test values. A new molecular clock indicates that molluscs had a terminal Precambrian origin with rapid divergence of all eight extant classes in the Cambrian. The recovery of Serialia as a derived, Late Cambrian clade is potentially in line with the stratigraphic chronology of morphologically heterogeneous early mollusc fossils. Serialia is in conflict with traditional molluscan classifications and recent phylogenomic data. Yet our hypothesis, as others from molecular data, implies frequent molluscan shell and body transformations by heterochronic shifts in development and multiple convergent adaptations, leading to the variable shells and body plans in extant lineages.

  7. Mollusks: how are they arranged in the rocky intertidal zone?

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    Débora R. A. Veras

    2013-06-01

    Full Text Available Mollusks occupy different kinds of environments, including the intertidal zone. The present study investigated the spatial distribution of mollusks on beach rocks of the intertidal zone of Pacheco Beach in the state of Ceará, Brazil. Sampling occurred from August 2006 to September 2007. Across two transects, six samples of 0.25 m² were collected monthly in gaps of 30 m (0 m, 30 m, 60 m, 90 m, 120 m and 150 m. The mollusks were counted in field, and samples of sediment and algae were taken for further analysis. A total of 74,515 individuals were found and classified into 67 species, 52 genera and 39 families. Gastropods were predominant, corresponding to 73.1% of the species, followed by bivalves (22.4% and chitons (4.5%. Caecum ryssotitum de Folin, 1867 was the most abundant taxon, representing 68.8% of total specimen findings. In general, species were mostly found in Middle Littoral zone (samples 60 m and 90 m, suggesting that the greater number of microenvironments available in this area may contribute to establishment and survival.

  8. 18S ribosomal DNA sequences provide insight into the phylogeny of patellogastropod limpets (Mollusca: Gastropoda).

    Science.gov (United States)

    Yoon, Sook Hee; Kim, Won

    2007-02-28

    To investigate the phylogeny of Patellogastropoda, the complete 18S rDNA sequences of nine patellogastropod limpets Cymbula canescens (Gmelin, 1791), Helcion dunkeri (Krauss, 1848), Patella rustica Linnaeus, 1758, Cellana toreuma (Reeve, 1855), Cellana nigrolineata (Reeve, 1854), Nacella magellanica Gmelin, 1791, Nipponacmea concinna (Lischke, 1870), Niveotectura pallida (Gould, 1859), and Lottia dorsuosa Gould, 1859 were determined. These sequences were then analyzed along with the published 18S rDNA sequences of 35 gastropods, one bivalve, and one chiton species. Phylogenetic trees were constructed by maximum parsimony, maximum likelihood, and Bayesian inference. The results of our 18S rDNA sequence analysis strongly support the monophyly of Patellogastropoda and the existence of three subgroups. Of these, two subgroups, the Patelloidea and Acmaeoidea, are closely related, with branching patterns that can be summarized as [(Cymbula + Helcion) + Patella] and [(Nipponacmea + Lottia) + Niveotectura]. The remaining subgroup, Nacelloidea, emerges as basal and paraphyletic, while its genus Cellana is monophyletic. Our analysis also indicates that the Patellogastropoda have a sister relationship with the order Cocculiniformia within the Gastropoda.

  9. Common mechanics of mode switching in locomotion of limbless and legged animals.

    Science.gov (United States)

    Kuroda, Shigeru; Kunita, Itsuki; Tanaka, Yoshimi; Ishiguro, Akio; Kobayashi, Ryo; Nakagaki, Toshiyuki

    2014-06-06

    Crawling using muscular waves is observed in many species, including planaria, leeches, nemertea, aplysia, snails, chitons, earthworms and maggots. Contraction or extension waves propagate along the antero-posterior axis of the body as the crawler pushes the ground substratum backward. However, the observation that locomotory waves can be directed forward or backward has attracted much attention over the past hundred years. Legged organisms such as centipedes and millipedes exhibit parallel phenomena; leg tips form density waves that propagate backward or forward. Mechanical considerations reveal that leg-density waves play a similar role to locomotory waves in limbless species, and that locomotory waves are used by a mechanism common to both legged and limbless species to achieve crawling. Here, we report that both mode switching of the wave direction and friction control were achieved when backward motion was induced in the laboratory. We show that the many variations of switching in different animals can essentially be classified in two types according to mechanical considerations. We propose that during their evolution, limbless crawlers first moved in a manner similar to walking before legs were obtained. Therefore, legged crawlers might have learned the mechanical mode of movement involved in walking long before obtaining legs.

  10. Patterns of Mass Mortality among Rocky Shore Invertebrates across 100 km of Northeastern Pacific Coastline.

    Science.gov (United States)

    Jurgens, Laura J; Rogers-Bennett, Laura; Raimondi, Peter T; Schiebelhut, Lauren M; Dawson, Michael N; Grosberg, Richard K; Gaylord, Brian

    2015-01-01

    Mass mortalities in natural populations, particularly those that leave few survivors over large spatial areas, may cause long-term ecological perturbations. Yet mass mortalities may remain undocumented or poorly described due to challenges in responding rapidly to unforeseen events, scarcity of baseline data, and difficulties in quantifying rare or patchily distributed species, especially in remote or marine systems. Better chronicling the geographic pattern and intensity of mass mortalities is especially critical in the face of global changes predicted to alter regional disturbance regimes. Here, we couple replicated post-mortality surveys with preceding long-term surveys and historical data to describe a rapid and severe mass mortality of rocky shore invertebrates along the north-central California coast of the northeastern Pacific Ocean. In late August 2011, formerly abundant intertidal populations of the purple sea urchin (Strongylocentrotus purpuratus, a well-known ecosystem engineer), and the predatory six-armed sea star (Leptasterias sp.) were functionally extirpated from ~100 km of coastline. Other invertebrates, including the gumboot chiton (Cryptochiton stelleri) the ochre sea star (Pisaster ochraceus), and subtidal populations of purple sea urchins also exhibited elevated mortality. The pattern and extent of mortality suggest the potential for long-term population, community, and ecosystem consequences, recovery from which may depend on the different dispersal abilities of the affected species.

  11. Acute toxicities of crude oils and oil-dispersant mixtures to Red sea fishes and invertebrates

    Energy Technology Data Exchange (ETDEWEB)

    Eisler, R.

    1975-11-01

    Crude oil from fields in the Persian Gulf and in the Sinai plus a chemical oil dispersant were tested, using static bioassay procedures, for toxicity to adults or juveniles of ten marine species: Heteroxenia fuscescens, a soft coral; Nerita forskali and Drupa granulata, gastropod molluscs; Mytilus variabilis, a mussel; Acanthopleura haddoni, a chiton (mollusc); Echinometra mathaei, sea urchin; Calcinus latens, a hermit crab; Palaemon pacificus, a shrimp; Parupeneus barberinus, goatfish; and Siganus rivulatus, rabbitfish. Concentrations fatal to 50 percent of individual test species in 168 hours, LC-50 (168 h), ranged from 0.74 to more than 30.0 ml/liter for Persian Gulf crude, from 14.5 to more than 30.0 ml/liter for Sinai crude, and from 0.006 to 0.064 ml/liter for the dispersant. In general, fishes and crustaceans were the most sensitive groups assayed and molluscs the most resistant. LC-50 (168 h) values for oil-dispersant mixtures of 10 parts oil to 1 part dispersant (v/v) for selected species ranged from 0.047 to 0.152 ml/liter which appears to reflect the biocidal properties of the dispersant. Some individuals that survived immersion in high concentrations of the test compounds for 168 h were adversely affected during treatment and afterwards.

  12. Positive and negative effects of mesograzers on early-colonizing species in an intertidal rocky-shore community.

    Science.gov (United States)

    Tejada-Martinez, Daniela; López, Daniela N; Bonta, César C; Sepúlveda, Roger D; Valdivia, Nelson

    2016-08-01

    The ecological consequences of human-driven overexploitation and loss of keystone consumers are still unclear. In intertidal rocky shores over the world, the decrease of keystone macrograzers has resulted in an increase in the dominance of herbivores with smaller body (i.e., "mesograzers"), which could potentially alter community assembly and structure. Here, we experimentally tested whether mesograzers affect the structure of rocky intertidal communities during the period of early colonization after the occurrence of a disturbance. A manipulative field experiment was conducted to exclude mesograzers (i.e., juvenile chitons, small snails, amphipods, and juvenile limpets) from experimental areas in an ecosystem characterized by the overexploitation of keystone macrograzers and predators. The results of multivariate analyses suggest that mesograzers had significant effects on intertidal community structure through negative and positive effects on species abundances. Mesograzers had negative effects on filamentous algae, but positive effects on opportunistic foliose algae and barnacles. Probably, mesograzers indirectly favored the colonization of barnacles and foliose algae by removing preemptive competitors, as previously shown for other meso- and macrograzer species. These results strongly support the idea that small herbivores exert a firm controlling effect on the assembly process of natural communities. Therefore, changes in functional roles of top-down controllers might have significant implications for the structure of intertidal communities.

  13. Patterns of Mass Mortality among Rocky Shore Invertebrates across 100 km of Northeastern Pacific Coastline.

    Directory of Open Access Journals (Sweden)

    Laura J Jurgens

    Full Text Available Mass mortalities in natural populations, particularly those that leave few survivors over large spatial areas, may cause long-term ecological perturbations. Yet mass mortalities may remain undocumented or poorly described due to challenges in responding rapidly to unforeseen events, scarcity of baseline data, and difficulties in quantifying rare or patchily distributed species, especially in remote or marine systems. Better chronicling the geographic pattern and intensity of mass mortalities is especially critical in the face of global changes predicted to alter regional disturbance regimes. Here, we couple replicated post-mortality surveys with preceding long-term surveys and historical data to describe a rapid and severe mass mortality of rocky shore invertebrates along the north-central California coast of the northeastern Pacific Ocean. In late August 2011, formerly abundant intertidal populations of the purple sea urchin (Strongylocentrotus purpuratus, a well-known ecosystem engineer, and the predatory six-armed sea star (Leptasterias sp. were functionally extirpated from ~100 km of coastline. Other invertebrates, including the gumboot chiton (Cryptochiton stelleri the ochre sea star (Pisaster ochraceus, and subtidal populations of purple sea urchins also exhibited elevated mortality. The pattern and extent of mortality suggest the potential for long-term population, community, and ecosystem consequences, recovery from which may depend on the different dispersal abilities of the affected species.

  14. Polyplacophora (Mollusca from reef ecosystems and associations with macroalgae on the Coast of Alagoas, Northeastern Brazil

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    Monica Dorigo Correia

    2015-08-01

    Full Text Available ABSTRACT Brazilian marine molluscs, especially Gastropoda and Bivalvia, are relatively well studied. However, information on the class Polyplacophora is more scarce, particularly on reef-dwelling forms. This study aimed to qualitatively and quantitatively analyze aspects of polyplacophorans from reef ecosystems and their associations with macroalgae on the coast of Maceió (state of Alagoas, Brazilian Northeast. The study area included five coral reefs at Ipioca, Ponta do Prego, Ponta do Meirim, Riacho Doce and Ponta Verde, as well as two sandstone reefs, located in Guaxuma and Sereia. The samples were obtained by snorkelling along the intertidal and subtidal reef zones to a depth of up to five meters during low tides, between 2009 and 2011. In addition, the chitons associated with three macroalgae of the Ponta Verde coral reef were studied based on collections made over 12 years (from the summer of 1998 to the winter of 2009. Three replicates with an area of 25 cm2 were collected from each of the following species of macroalgal phytals: Amphiroa fragilissima (Rhodophyta, Caulerpa racemosa (Chlorophyta and Dictyota cervicornis (Phaeophyta. A total of 715 individuals (110 juveniles and 605 adults were identified, including Acanthochitona terezae Guerra, 1983, Ischnochiton striolatus (Gray, 1828 and Ischnoplax pectinata (Sowerby II, 1840. Acanthochitona terezae was found for the first time in the area. Ischnochiton striolatus was the most abundant species in the reef ecosystem and in association with macroalgae. The greatest number of individuals of all three polyplacophorans identified (adults and juveniles was found on the phytal A. fragilissima.

  15. The macroalgal carbonate factory at a cool-to-warm temperate marine transition, Southern Australia

    Science.gov (United States)

    James, Noel P.; Reid, Catherine M.; Bone, Yvonne; Levings, Andrew; Malcolm, Isabelle

    2013-06-01

    The shallow neritic seafloor to depths of ~ 30 m along the coast of southwestern Victoria Australia, is the site of rocky reefs on volcanic and aeolianite bathymetric highs. The region, located near the warm- to cool-temperate environmental transition, is a site of prolific macroalgae (kelp) growth. Kelps are most prolific and diverse in high-energy, open-ocean environments whereas broad-leafed seagrasses, at their cold-water eastern limit, are restricted to local protected embayments. The seagrasses are reduced to one species of Amphibolis whereas the kelps are diverse and include the large intertidal bull kelp (Durvillaea), not present in warmer waters. The macroalgal forest extends from the intertidal to ~ 30 mwd (metres water depth) as a series of distinct biomes; 1) the Peritidal, 2) the Phaeophyte Forest (0-17 mwd), 3) the Rhodophyte Thicket (17-15 mwd), and 4) the Invertebrate Coppice (> 25 mwd). The Phaeophyte Forest is partitioned into a Durvillaea zone (0-2 mwd), a Phyllospora zone (2-10 mwd) and an Ecklonia zone (10-17mwd). The two major habitats within each biome comprise 1) an upward facing illuminated surface that supports a macroalgal canopy over an understorey of coralline algae and herbivorous gastropods, and 2) a separate, cryptic, shaded habitat dominated by a diverse community of filter-feeding invertebrates. These communities produce two different sediments; 1) geniculate and encrusting corallines and diverse gastropods from the upper surface, and 2) bryozoans, molluscs, barnacles, chitons, serpulids, and benthic foraminifers from the shaded, cryptic habitats. These particles are blended together with the latter becoming proportionally more abundant with increasing depth. Results of this study, when integrated with recent investigations in warm-temperate (South Australia) and cool-temperate (New Zealand) environments now define carbonate sedimentology of the macroalgal reef depositional system in this part of the northern Southern Ocean.

  16. Benthic food web structure in the Comau fjord, Chile (∼42°S): Preliminary assessment including a site with chemosynthetic activity

    Science.gov (United States)

    Zapata-Hernández, Germán; Sellanes, Javier; Mayr, Christoph; Muñoz, Práxedes

    2014-12-01

    Using C and N stable isotopes we analyzed different trophic aspects of the benthic fauna at two sites in the Comau fjord: one with presence of venting of chemically reducing fluids and extensive patches of bacterial mats (XH: X-Huinay), and one control site (PG: Punta Gruesa) with a typical fjord benthic habitat. Due to the widespread presence of such microbial patches in the fjord and their recognized trophic role in reducing environments, we hypothesize that these microbial communities could be contributing to the assimilated food of consumers and transferring carbon into high trophic levels in the food web. Food sources in the area included macroalgae with a wide range of δ13C values (-34.7 to -11.9‰), particulate organic matter (POM, δ13C = -20.1‰), terrestrial organic matter (TOM, δ13C = -32.3‰ to -27.9‰) and chemosynthetic filamentous bacteria (δ13C = ∼-33‰). At both sites, fauna depicted typical values indicating photosynthetic production as a main food source (>-20‰). However, at XH selected taxa reported lower δ13C values (e.g. -26.5‰ in Nacella deaurata), suggesting a partial use of chemosynthetic production. Furthermore, enhanced variability at this site in δ13C values of the polyplacophoran Chiton magnificus, the limpet Fissurella picta and the tanaid Zeuxoides sp. may also be responding to the use of a wider scope of primary food sources. Trophic position estimates suggest three trophic levels of consumers at both sites. However, low δ15N values in some grazer and suspension-feeder species suggest that these taxa could be using other sources still to be identified (e.g. bacterial films, microalgae and organic particles of small size-fractions). Furthermore, between-site comparisons of isotopic niche width measurements in some trophic guilds indicate that grazers from XH have more heterogenic trophic niches than at PG (measured as mean distance to centroid and standard deviation of nearest neighbor distance). This last could be

  17. Micromorphological changes over time observed in the Vestfold Podzol chronosequence, SE Norway

    Science.gov (United States)

    Sauer, Daniela; Musztyfaga, Elżbieta; Sørensen, Rolf; Svendgård-Stokke, Siri; Rennert, Thilo; Sperstad, Ragnhild; Fuchs, Markus

    2016-04-01

    The Oslofjord region in SE-Norway has undergone steady glacio-isostatic uplift all over the Holocene. Hence, in the coastal areas land surface age continuously increases with elevation, providing ideal conditions for studying soil development with time. A chronosequence of soils on beach sand and sandy terraces of the Lågen River, showing progressive podzolisation with soil age, was studied in the Vestfold region, on the western side of the Oslofjord. In total, 31 pedons with soil ages ranging from 85 years (0.25 m a. s. l.) to ca. 10,150 years (62 m a. s. l.) were described and analysed. Soil ages were estimated by relating elevations of the sites to a Holocene relative sea level curve based on twelve AMS 14C-dates of gyttja from the isolation contact (marine/fresh water boundary) and six marine macrofossil 14C-dates (Sørensen et al., 2012). The climate in the study area is comparatively mild, with mean annual temperatures ranging from 5.3 °C (Ramnes) to 6.3 °C (Sandefjord, Larvik) and mean annual precipitation of 909 mm (Sandefjord) to 1150 mm (Stokke). The predominating vegetation is mixed forest. The parent material of the soils consists of 70-95% sand in most profiles, composed mainly of quartz and feldspars. Under these conditions, initial podzolisation becomes visible after 800-1200 years, and the development of a major Podzol requires about 6000 years. Bh and Bs horizons occur first in the 1220 year-old soil. Their combined thickness shows a logarithmic increase over time. Micromorphological changes of the Bh and Bs horizons with soil age include accumulation of increasing amounts of dark fine material in the Bh horizons and cloudy, iron-rich, reddish fine material in the Bs horizons over time. These accumulations turn the original coarse monic c/f-related distribution into chitonic and enaulic c/f-related distribution in the Bh and Bs horizons. The reddish colour of the granules of fine material in the Bs horizons becomes more intense with soil age. In

  18. Los patelogastrópodos intermareales de Chile y Perú Intertidal limpets of Chile and Peru

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    CARMEN ESPOZ

    2004-06-01

    diversos del mundo. Más aún, esta variabilidad y flexibilidad pueden ser responsables de las confusiones taxonómicas que han rodeado a este conjunto faunísticoIn this study we present a classification system reflecting the phylogenetic relationships for the intertidal patellogastropods of Chile and Peru. We infer phylogenetic relationships between limpets species using DNA sequences from the 16S region of the mitochondrial genome. We include a comparative limpet study of: shell structure, color and morphological patterns of the shell, radular teeth and anatomy. Additionally, we provide information about the distribution and ecology for members of this group within the studied area. The results show a Chilean-Peruvian Lottiidae fauna consisting of at least nine species, which are grouped into a single monophyletic clade Scurria (S. variabilis, S. zebrina, S. viridula, S. plana, S. scurra, S. araucana, S. ceciliana and a non identificated species, and a "problematic taxon" preliminarily assigned to the genus Lottia (Lottia orbignyi. The group of species is present in the intertidal rocky shores between 5º S and 54º S, from the upper to the lower intertidal fringes, ranging from exposed to protected areas. The systematic outcome of this study suggests the synonymization of S. parasitica to S. variabilis, and of S. ceciliana to S. boehmita. According to our field results, the species S. variabilis shows at least three ecophenotypes: (1 on rocky substrates along the full geographic range, (2 on the shells of the key-hole limpets: Fissurella crassa and F. limbata mainly in central and south of Chile, and (3 on the chiton plates of Enoplochiton niger in the north of Chile and south of Perú. S. ceciliana is a species in which morphology and color patterns are highly variable. In general, this variability indicates that the Chilean-Peruvian limpet species are among the most complex and diverse limpet fauna in the world. This, may reflects the taxonomic confusion which has