The shallow marine ostracod communities of the Azores (Mid- North Atlantic): taphonomy and palaeoecology

Authors

  • R. PIAZZA MEIRELES CIBIO, Centro de Investigação em Biodiversidade e Recursos Genéticos, InBIO Laboratório Associado, Pólo dos Açores – Departamento de Biologia da Universidade dos Açores 9501-801, Ponta Delgada, Açores, Portugal. MPB – Marine PalaeoBiogeography Working Group, University of the Azores Azores, Portugal
  • D. KEYSER Zoological Institute and Museum, University of Hamburg Martin-Luther-King Platz 3, 20146 Hamburg, Germany.
  • P.A. BORGES Department of Geoscience, University of the Azores Ponta Delgada, Azores, Portugal.
  • L. SILVA CIBIO, Centro de Investigação em Biodiversidade e Recursos Genéticos, InBIO Laboratório Associado, Pólo dos Açores – Departamento de Biologia da Universidade dos Açores 9501-801, Ponta Delgada, Açores, Portugal.
  • A.M. DE FRIAS MARTINS CIBIO, Centro de Investigação em Biodiversidade e Recursos Genéticos, InBIO Laboratório Associado, Pólo dos Açores – Departamento de Biologia da Universidade dos Açores 9501-801, Ponta Delgada, Açores, Portugal.
  • S.P. ÁVILA CIBIO, Centro de Investigação em Biodiversidade e Recursos Genéticos, InBIO Laboratório Associado, Pólo dos Açores – Departamento de Biologia da Universidade dos Açores 9501-801, Ponta Delgada, Açores, Portugal. MPB – Marine PalaeoBiogeography Working Group, University of the Azores Azores, Portugal Faculdade de Ciências da Universidade do Porto Rua Campo Alegre 1021/1055, 4169-007 Porto

DOI:

https://doi.org/10.1344/105.000002073

Keywords:

Ostracods, Recent, Oceanic island, Taphonomic processes, Palaeoecology, Bayesian model

Abstract

This is the first palaeoecological and taphonomical study of the Recent marine ostracods from the Azores. The aims of this work were to address the following questions: i) to establish the typical ostracod assemblages from the shallow waters of the Azores; ii) to determine the bathymetric ranges for each ostracod species; iii) to investigate the time span and depth in which significant transport occurs; iv) to quantify the amount of out of habitat transport between sandy beaches, tide pools and the sublittoral; v) to determine distinctive taphonomic features that can be used to recognize the amount of temporal resolution in ostracod assemblages. Fifteen species were recovered, representing 8 families and 12 genera (Loxoconcha, Neonesidea, Xestoleberis, Aurila, Urocythereis, Heterocythereis, Carinocythereis, Callistocythere, Leptocythere, Semicytherura, Lanceostoma and Cylindroleberis). The living assemblages are dominated by specimens of the Loxoconchidae, Xestoleberidae and Hemicytheridae, whereas the dead assemblages are dominated by specimens of the Loxoconchidae, Hemicytheridae, Bairdiidae, Xestoleberidae and Trachyleberidae. The shift from life-dominated assemblages in the shallower depths to death-dominated assemblages at greater depths is a consequence of significant transport downwards. The abundance of ostracods is higher in the first 10-20 m depth, especially in fine to medium sandy substrates. Considerable differences among islands were supported by the Bayesian model, as a consequence of the physical and hydrodynamic factors that differently affect each of the Azorean islands. Large-scale (sea-surface currents, Holocene relative sea-level, storms) and small-scale processes are responsible for shaping the Azorean Recent marine ostracod communities. No living specimens were found in the samples collected at the beach faces, thus reinforcing former interpretations of one of the authors (S. Ávila) that advocate that at a global scale, sandy beaches in oceanic islands located at temperate latitudes are almost or even completely devoid of life due to historical reasons related with the sea level changes.

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PIAZZA MEIRELES R, KEYSER D, BORGES P, SILVA L, DE FRIAS MARTINS A, ÁVILA S. The shallow marine ostracod communities of the Azores (Mid- North Atlantic): taphonomy and palaeoecology. GeA [Internet]. 2014Jun.17 [cited 2021Aug.3];12(1):53-70. Available from: https://revistes.ub.edu/index.php/GEOACTA/article/view/105.000002073

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