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Advisor(s)
Abstract(s)
Living (stained) benthic foraminiferal faunas were analyzed
in 51 surficial sediment samples taken from the northern Gulf
of Cadiz continental shelf between the mouths of the
Guadiana and Guadalquivir rivers. The distribution and
abundance of 26 species with relative abundance .5% were
related to water depth, sediment type, river discharge, water
temperature, salinity, turbidity, and primary productivity.
Hierarchical classification using R- and Q-mode cluster
analyses, and individual distributions, allowed these taxa to
be categorized into four general groups. Group 1 is
represented by Bolivina ordinaria and Hopkinsina atlantica.
These species are linked to river discharge, and are associated
with muddy sediments. They are considered the most
opportunistic species in the assemblage, and are associated
with the limits of productivity. Group 2, contains Ammonia
beccarii, Eggerelloides scaber, Elphidium gerthi, Quinqueloculina
laevigata, and Q. stelligera, and is characteristic of
shallow water depths. Its species are associated with different
sediment types and their distribution is influenced by river
discharge. Group 3 is dominated by Bulimina aculeata, B.
elongata, Elphidium excavatum, E. cuvillieri, Epistominella
vitrea, and Rectuvigerina phlegeri. These species display the
highest abundances between 30–100 m water depths. They
prevail in muds associated with weak hydrodynamics, low
oxygenation, and high organic matter. Group 4 includes
species that are more abundant in deep stations and is divided
into two subgroups. Subgroup 4A includes Bolivina catanensis,
B. italica, B. striatula, Cassidulina laevigata, Stainforthia
sp., Nouria polymorphinoides, and Nouria sp., with higher
abundances in one or two samples. Subgroup 4B, with
Brizalina dilatata, B. spathulata, Bulimina marginata,
Nonionella iridea, N. stella, and N. turgida, has patchy
distribution. Higher abundances of Nonionella species off the
Guadiana River are related to low temperature and salinity.
Description
Keywords
Benthic Foraminifera Ecology Continental shelf Environmental indicators
Citation
Mendes, I., Dias, J.A., Schönfeld, J., Ferreira, Ó., 2012. Distribution of living benthic foraminifera on the Northern Gulf of Cadiz continental shelf. Journal of Foraminiferal Research, 42(1), 18-38.
Publisher
Cushman Foundation for Foraminiferal Research