Vertical niche separation control of diversity and size disparity in planktonic Foraminifera

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doi: 10.1016/j.marmicro.2006.11.002
Author(s): Al-Sabouni, Nadia; Kucera, Michal; Schmidt, Daniela N.
Author Affiliation(s): Primary:
University of London, Royal Holloway, Department of Geology, London, United Kingdom
Eberhard Karls University of Tübingen, Federal Republic of Germany
University of Bristol, United Kingdom
Volume Title: Marine Micropaleontology
Source: Marine Micropaleontology, 63(1-2), p.75-90. Publisher: Elsevier, Amsterdam, Netherlands. ISSN: 0377-8398 CODEN: MAMIDH
Note: In English. 60 refs.; illus., incl. 2 tables, sketch map
Summary: Species distribution patterns in planktonic foraminiferal assemblages are fundamental to the understanding of the determinants of their ecology. Until now, data used to identify such distribution patterns was mainly acquired using the standard >150 µm sieve size. However, given that assemblage shell size-range in planktonic foraminifera is not constant, this data acquisition practice could introduce artefacts in the distributional data. Here, we investigated the link between assemblage shell size-range and diversity in Recent planktonic foraminifera by analysing multiple sieve-size fractions in 12 samples spanning all bioprovinces of the Atlantic Ocean. Using five diversity indices covering various aspects of community structure, we found that counts from the >63 µm fraction in polar oceans and the >125 µm elsewhere sufficiently approximate maximum diversity in all Recent assemblages. Diversity values based on counts from the >150 µm fraction significantly underestimate maximum diversity in the polar- and surprisingly also in the tropical provinces. Although the new methodology changes the shape of the diversity/sea-surface temperature (SST) relationship, its strength appears unaffected. Our analysis reveals that increasing diversity in planktonic foraminiferal assemblages is coupled with a progressive addition of larger species that have distinct, offset shell-size distributions. Thus, the previously documented increase in overall assemblage shell size-range towards lower latitudes is linked to an expanding shell-size disparity between species from the same locality. This observation supports the idea that diversity and shell size-range disparity in foraminiferal assemblages are the result of niche separation. Increasing SST leads to enhanced surface water stratification and results in vertical niche separation, which permits ecological specialisation. Specific deviations from the overall diversity and shell-size disparity latitudinal pattern are seen in regions of surface-water instability, indicating that coupled shell-size and diversity measurements could be used to reconstruct water column structures of past oceans. Abstract Copyright (2007) Elsevier, B.V.
Year of Publication: 2007
Research Program: ODP Ocean Drilling Program
Key Words: 07 Marine Geology and Oceanography; Atlantic Ocean; Biodiversity; Biogeography; Biozones; Ceara Rise; Cenozoic; Foraminifera; Habitat; Holocene; Invertebrata; Leg 154; Microfossils; New methods; North Atlantic; ODP Site 926; Ocean Drilling Program; Paleo-oceanography; Paleoecology; Planktonic taxa; Protista; Quaternary; Sea-surface temperature; Size; South Atlantic
Coordinates: N034309 N034309 W0425430 W0425430
Record ID: 2007116482
Copyright Information: GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data from CAPCAS, Elsevier Scientific Publishers, Amsterdam, Netherlands