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Ecological distribution of recent deep-water Foraminifera around New Zealand

Bruce W. Hayward, Ashwaq T. Sabaa, Hugh R. Grenfell, Helen Neil and Helen Bostock
Ecological distribution of recent deep-water Foraminifera around New Zealand
Journal of Foraminiferal Research (October 2013) 43 (4): 415-442

Abstract

Census counts (>63 mu m) of 461 species in 361 samples are used as the basis for recognizing and mapping associations of deep-sea benthic foraminifera (50-5000-m depth) around New Zealand, southwest Pacific (28-60 degrees S, 155 degrees E-170 degrees W). Fourteen faunal associations are identified by cluster analysis with five of these subdivided into 20 subassociations. The deepest associations, dominated by Nuttallides spp., Globocassidulina subglobosa, and diverse agglutinated species, occur at middle-lower abyssal depths (>3600 m) right around New Zealand, where they have been impacted by differing levels of taphonomic modifications. Two large associations are widespread throughout the region: one (Alabaminella weddellensis-Epistominella exigua) at lower bathyal-middle abyssal depths (approximately 1500-4000 m) and the other (Cassidulina carinata-A. weddellensis-Abditodentrix pseudothalmanni) mostly at mid-bathyal-upper abyssal depths (approximately 500-3000 m). Two deep-water associations occur on current-swept submarine highs: one (Trifarina angulosa-Ehrenbergina glabra) at lower bathyal-upper abyssal depths (1000-2400 m) along the southeastern margin of the Camp-bell and Bounty plateaux and the other (Bolivina robusta-Globocassidulina canalisuturata) at mid-upper bathyal depths in coarse sediment east and southeast of New Zealand. Two large associations occur at mid-shelf-uppermost-bathyal depths (50-400 m): one (Cassidulina carinata-Bulimina marginata-Gavelinopsis praegeri) around the coast beneath warm Subtropical Water and the other (C. carinata-T. angulosa-G. praegeri) further south beneath the cooler Subtropical Front and Subantarctic Water. A major reason for this study was to understand the environmental drivers of foraminiferal faunal distribution in this region to assist in paleoenvironmental interpretations of fossil faunas which have a significant regional character. Canonical correspondence analysis indicates that the distribution of bathyal and abyssal associations is more strongly influenced by depth-related variables, while shallower associations are influenced by latitude-related differences in surface-water characteristics. Environmental variables that influence faunal patterns at abyssal and bathyal depths appear to be, in decreasing order: food supply (organic-carbon flux, chlorophyll-a proxies), bottom-oxygen concentration, and carbonate corrosiveness (Fragmentation Index, planktic % proxies). Latitude-related variables driving mid-shelf-uppermost bathyal faunal patterns are water temperature, followed by primary productivity (phosphate and chlorophyll-a proxies). Environmental variables related to bottom-current strength appear to drive the faunal composition of three associations at shelf and bathyal depths. Cluster analysis enables the recognition of 22 anomalously deep faunas that are inferred to have a significant displaced content. There are no significant diversity trends correlated with depth, but species diversity decreases with increasing latitude at all depths.


ISSN: 0096-1191
EISSN: 1943-264X
Coden: JFARAH
Serial Title: Journal of Foraminiferal Research
Serial Volume: 43
Serial Issue: 4
Title: Ecological distribution of recent deep-water Foraminifera around New Zealand
Affiliation: Geomarine Research, Auckland, New Zealand
Pages: 415-442
Published: 201310
Text Language: English
Publisher: Cushman Foundation for Foraminiferal Research, Ithaca, NY, United States
References: 108
Accession Number: 2013-088921
Categories: Invertebrate paleontology
Document Type: Serial
Bibliographic Level: Analytic
Annotation: Includes 6 appendices
Illustration Description: illus. incl. 5 tables, sketch maps
S47°30'00" - S34°30'00", E166°30'00" - E178°30'00"
Secondary Affiliation: National Institute of Water and Atmosphere, NZL, New Zealand
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2018, American Geosciences Institute. Abstract, Copyright, Cushman Foundation for Foraminiferal Research. Reference includes data from GeoScienceWorld, Alexandria, VA, United States
Update Code: 201352
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