BIOCENOSES OF BENTHIC FORAMINIFERA OF THE AVEIRO CONTINENTAL SHELF (PORTUGAL): INFLUENCE OF THE UPWELLING EVENTS AND OTHER SHELF PROCESSES

Authors

  • Maria Virgínia Alves Martins Universidade do Estado do Rio de Janeiro, Faculdade de Geologia, Departamento de Estratigrafia e Paleontologia. Av. São Francisco Xavier, 524, sala 2020A, Maracanã, 20550-013 Rio de Janeiro, RJ
  • João Carlos Moreno Universidade de Lisboa, Faculdade de Ciências, Centro e Departamento de Geologia, Campo Grande, 1749-016, Lisbon, Portugal
  • Peter Miller Plymouth Marine Laboratory, Prospect Place, The Hoe, Plymouth, PL1 3DH
  • Paulo Miranda Universidade de Aveiro, GeoBioTec, Departamento de Geociências, Campus de Santiago, 3810-193 Aveiro
  • Lazaro Laut Universidade Federal do Estado do Rio de Janeiro – UNIRIO, Laboratório de Micropaleontologia - LABMICRO, Av. Pasteur, 458, IBIO/CCET, sala 500, Urca, Rio de Janeiro - RJ – Brazil, CEP 22.290-255
  • André Eduardo Piacentini Pinheiro Faculdade de Formação de Professores - FFP (UERJ), Universidade do Estado do Rio de Janeiro, Rua Dr. Francisco Portela, 1470 – Patronato, CEP: 24435-005 - São Gonçalo – RJ
  • Cintia Yamashita Universidade do Estado do Rio de Janeiro, Faculdade de Geologia, Departamento de Estratigrafia e Paleontologia. Av. São Francisco Xavier, 524, sala 2020A, Maracanã, 20550-013 Rio de Janeiro, RJ
  • Denise Lara Terroso Universidade de Aveiro, GeoBioTec, Departamento de Geociências, Campus de Santiago, 3810-193 Aveiro, Portugal.
  • Fernando Rocha Universidade de Aveiro, GeoBioTec, Departamento de Geociências, Campus de Santiago, 3810-193 Aveiro,
  • Cristina Bernardes Universidade de Aveiro, CESAM, Departamento de Geociências, Campus de Santiago, 3810-193 Aveiro

DOI:

https://doi.org/10.12957/jse.2017.28041

Keywords:

Living benthic foraminifera. Upwelling index. Total organic matter. Sediment granulometry. Portuguese continental margin

Abstract

This work aims to compare the dimensions and composition of benthic foraminiferal biocenoses (living specimens) during two summer sampling events. Forty-four sediment samples were collected on the Aveiro Continental Shelf (Center of Portugal) (latitude of 40º30'N-40º50'N, longitude of 8º46'W-9º20'W) for granulometry, total organic matter (TOM) and living foraminiferal analyses.

The sediment samples were collected during summers of 1994 and 1995, on stations located along transects (east-west direction) and between the bathymetries of 10-200 m. During the sampling campaigns, measurements of salinity, temperature and density data were recorded in the water column.

The results showed that the living assemblages were mainly found in stations located between 20-80 m depth. The abundance of living foraminifera was generally reduced at depths <20 m in the so-called “coastal deposits”, where the sediments are frequently remobilized and transported by the littoral drift. Living benthic foraminiferal densities were also reduced in stations at 80-200 m depth, despite the high sedimentary TOM contents. Results obtained in this work indicate that, in this marine setting, the most determinant factors for the dimension and composition of living foraminifera are not the sediments’ granulometry and organic matter content. In fact, the coastal dynamics, sediment stability, availability of quality food, among other factors, such as the bottom salinity oscillations and their combination, should better explain the abundance of living foraminifera and the biocenoses composition.

Published

2017-03-26

Issue

Section

Research article