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Over 100 years of environmental change recorded by foraminifers and sediments in a large Gulf of Mexico estuary, Mobile Bay, AL, USA

Estuarine and Continental Shelf Science

By:
,
DOI: 10.1016/j.ecss.2012.10.001

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Abstract

The marine microfauna of Mobile Bay has been profoundly influenced by the development and expansion of the primary shipping channel over the last ˜100 years. Foraminifers and sediments from seven box cores with excess lead-210 chronology document that channel dredging and spoil disposal have altered circulation, reduced estuarine mixing, changed sedimentation patterns, and caused a faunal turnover within the bay. Beginning in the late 1800s, changes in estuarine mixing allowed for greater low-pH freshwater influence in the bay, and ultimately began environmental changes that resulted in the loss of calcareous foraminifers. By the early 1900s, box cores throughout Mobile Bay record a ˜ 100-year trend of increasing calcareous test dissolution that continues to the present. Since the completion of the current shipping channel in the 1950s, restricted tidal flushing and increased terrestrial organic matter, documented by carbon-to-nitrogen ratios, stimulated an increase in agglutinated foraminiferal densities. However, in deeper areas of the bay, hypoxic water has negatively impacted the marine microfauna. Comparisons of the present-day foraminiferal assemblage with foraminifers collected in the early 1970s indicate that the continued biologic loss of calcareous foraminifers in the bay has allowed the introduction of a new agglutinated foraminiferal species into the bay.

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Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Over 100 years of environmental change recorded by foraminifers and sediments in a large Gulf of Mexico estuary, Mobile Bay, AL, USA
Series title:
Estuarine and Continental Shelf Science
DOI:
10.1016/j.ecss.2012.10.001
Volume
115
Year Published:
2012
Language:
English
Publisher:
Elsevier
Publisher location:
Amsterdam, Netherlands
Contributing office(s):
St. Petersburg Coastal and Marine Science Center
Description:
14 p.
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
Larger Work Title:
Estuarine and Continental Shelf Science
First page:
345
Last page:
358
Country:
United States
State:
Alabama
Other Geospatial:
Gulf Of Mexico;Mobile Bay
Additional Online Files(Y/N):
N