The Contribution of Fine Sieve Fractions (63–150 μm) to Foraminiferal Abundance and Diversity in an Area of the Eastern Pacific Ocean Licensed for Polymetallic Nodule Exploration

The sieve mesh sizes used in benthic foraminiferal studies exert a strong influence on faunal densities and composition. We examined the consequences of including finer (63–150 µm) size classes in a study of Rose Bengal stained (‘live’) and dead foraminifera in 5 megacorer samples (0–1 cm layer) fro...

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Bibliographic Details
Published in:Frontiers in Marine Science 2019-04, Vol.6
Main Authors: Gooday, Andrew J., Goineau, Aurélie
Format: Article
Language:English
Subjects:
Abundance
abyssal benthic foraminifera
baseline survey
Benthic communities
Benthos
biodiversity
Clarion-Clipperton Zone
Dominant species
Ecosystems
Exploration
Ferromanganese nodules
Foraminifera
Laboratories
Nodules
Ocean floor
polymetallic nodules
Sediments
sieve mesh size
Species
Studies
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Summary:The sieve mesh sizes used in benthic foraminiferal studies exert a strong influence on faunal densities and composition. We examined the consequences of including finer (63–150 µm) size classes in a study of Rose Bengal stained (‘live’) and dead foraminifera in 5 megacorer samples (0–1 cm layer) from abyssal sites in the eastern Clarion-Clipperton Zone (CCZ; equatorial Pacific), a region with commercially-significant deposits of polymetallic nodules. More than 60% of intact specimens originated from the finer (90%) to the finer fractions; the corresponding number for the stained + dead assemblage was 12 out of 35. Of the 46 most abundant species in both assemblages combined, 35 were monothalamids (mainly spheres, Lagenammina spp., Nodellum-like forms, and saccamminids), the remainder being rotaliids (3), hormosinids (3), trochamminids (3) and textulariids (2). By far the most abundant species overall, a tiny agglutinated sphere, was almost entirely confined to the finer fractions. Although small foraminifera that pass through a 150-µm screen are time-consuming to analyse, they constitute an important part of abyssal Pacific assemblages and may include opportunistic species that respond to episodic food pulses as well as pioneer recolonisers of defaunated substrates. It is therefore important to consider them in studies of seabed mining impacts on abyssal benthic communities
ISSN:2296-7745
2296-7745
DOI:10.3389/fmars.2019.00114