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GEOREF RECORD

Foraminifera of hydrocarbon seeps, Gulf of Mexico

Melissa K. Lobegeier and Barun K. Sen Gupta
Foraminifera of hydrocarbon seeps, Gulf of Mexico
Journal of Foraminiferal Research (April 2008) 38 (2): 93-116

Abstract

One hundred and eighty-three species of benthic Foraminifera were identified in a study of sediment substrates and tubeworm surfaces in (a) the Green Canyon, Garden Banks and Mississippi Canyon (245-1081 m) and (b) the Alaminos, Farnella and De Soto Canyons (1848-2918 m), Gulf of Mexico; the samples were obtained from submersibles in both seep and non-seep (control) areas. None of the species is endemic to seeps, but 20 species were previously unknown in the Gulf of Mexico. The imprint of water depth on foraminiferal assemblages is clearly detectable, because the species are recruited from the surrounding non-seep habitats. The two high-level surface-sample groups (clusters) recognized by numerical data analysis are distinguishable based on the bathymetric location of the sample sites. The shallower-water group contains all samples (seep and non-seep) from depths of 245-1081 m; the deeper-water (deepest-bathyal and abyssal) group contains all samples from 1848-2918 m. Foraminiferal species of wide-ranging morphologic and taxonomic affinities are able to maintain sizeable populations at sites of hydrocarbon seepage; the high bacterial productivity at the seeps could be a major factor in the sustenance of these populations. The most conspicuous dominants at seep-influenced substrates (bacterial mats) in the shallower cluster are endobenthic species, especially species of Bolivina, which are possibly facultative anaerobes. The pattern is not as clear in the deepest-bathyal and abyssal group, because some epibenthic species (e.g., Nuttallides decorata) are present among the dominants. In the shallower areas, the diversity (species richness) of both calcareous and agglutinated Foraminifera is higher in non-seep than in seep substrates. This distinction too is not clear in the deepest-bathyal and abyssal areas. Post-mortem mixing of species from different microhabitats could have elevated the diversity at some sites. Twelve sessile, epibenthic Foraminifera have been found to colonize surfaces of vestimentiferan tubeworms (and possibly other elevated microhabitats) at the seeps, centimeters to decimeters above the sediment-water interface. These attachment points are sufficiently above locations of gas escape in the seafloor to provide the species with an oxic microhabitat with little or no H (sub 2) S.


ISSN: 0096-1191
EISSN: 1943-264X
Coden: JFARAH
Serial Title: Journal of Foraminiferal Research
Serial Volume: 38
Serial Issue: 2
Title: Foraminifera of hydrocarbon seeps, Gulf of Mexico
Affiliation: Middle Tennessee State University, Department of Geosciences, Murfreesboro, TN, United States
Pages: 93-116
Published: 200804
Text Language: English
Publisher: Cushman Foundation for Foraminiferal Research, Ithaca, NY, United States
References: 87
Accession Number: 2008-080735
Categories: Invertebrate paleontology
Document Type: Serial
Bibliographic Level: Analytic
Annotation: Includes 4 appendices
Illustration Description: illus. incl. 4 plates, 5 tables, sketch map
N26°21'00" - N26°21'00", W94°28'60" - W94°28'60"
N26°19'60" - N28°10'00", W91°30'00" - W89°00'00"
Secondary Affiliation: Louisiana State University, USA, United States
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Abstract, Copyright, Cushman Foundation for Foraminiferal Research. Reference includes data from GeoScienceWorld, Alexandria, VA, United States
Update Code: 200823
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