Assemblage Comparisons of Living Benthic Foraminifera at Bathyal Sites Oiled and Un-Oiled by

242 Pages·2017·4.2 MB·English

The University of Southern Mississippi
The Aquila Digital Community
Master's Theses
Summer 8-2014
Assemblage Comparisons of Living Benthic Foraminifera at
Bathyal Sites Oiled and Un-Oiled by the Deepwater Horizon
Blowout in the Northeastern Gulf of Mexico
Valerie Joanna Cruz
University of Southern Mississippi
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Cruz, Valerie Joanna, "Assemblage Comparisons of Living Benthic Foraminifera at Bathyal Sites Oiled and
Un-Oiled by the Deepwater Horizon Blowout in the Northeastern Gulf of Mexico" (2014). Master's Theses.
52.
https://aquila.usm.edu/masters_theses/52
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The University of Southern Mississippi

ASSEMBLAGE COMPARISONS OF LIVING BENTHIC FORAMINIFERA
AT BATHYAL SITES OILED AND UN-OILED BY THE
DEEPWATER HORIZON BLOWOUT IN THE
NORTHEASTERN GULF OF MEXICO

by

Valerie Joanne Cruz

A Thesis
Submitted to the Graduate School
of The University of Southern Mississippi
in Partial Fulfillment of the Requirements
for the Degree of Master of Science

Approved:

Dr. Charlotte Brunner_______________
Committee Chair

Dr. Vernon Asper__________________

Dr. Kevin Briggs___________________

Dr. Maureen Ryan_________________
Dean of the Graduate School

August 2014
ABSTRACT
ASSEMBLAGE COMPARISONS OF LIVING BENTHIC FORAMINIFERA
AT BATHYAL SITES OILED AND UN-OILED BY THE
DEEPWATER HORIZON BLOWOUT IN THE
NORTHEASTERN GULF OF MEXICO
by Valerie Joanne Cruz
August 2014
Live benthic foraminiferal assemblages were studied at contaminated and
uncontaminated bathyal sites around the wellhead of the Deepwater Horizon oil
spill. Samples collected in October of 2010 and 2011 and summer of 2012 were
divided into uncontaminated (GIP 12, 21, K, and 25 and Obs0), moderately oiled
(GIP 16 and 17) and heavily oiled groups (GIP 15), in which the TPAH
concentrations ranged from 29 to 7,553 ng/g in 2010. Metric multidimensional
scaling (MDS) and cluster analyses were conducted to compare all surface
samples. Additionally, the heavily oiled site (GIP 15) and an uncontaminated site
(GIP 25) were studied downcore to assess the impact on the foraminiferal depth
of habitation (DOH).
A total of 284 species from 6 suborders have been identified in the ≥ 45-
μm size fraction. Three pseudo-replicates at Obs0 had more similarity in species
distribution and diversity than any other site. The MDS and cluster analyses
show that the surface assemblages are within a single biofacies except for two
sites (GIP 21 and K). The assemblages from the heavily oiled and un-oiled cores
were distinctly different. In 2010, the standing stock was nearly two times greater
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at the heavily oiled site, but the DOH was half the depth of the un-oiled site. In
2011, the standing stock of the two sites was similar, but the DOH remained
shallower at the oiled site. The trends in density, DOH, standing stock, diversity,
and abundance of an opportunistic species (Bulimina aculeata) at the heavily
oiled site appear consistent with hypertrophy.

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DEDICATION
I dedicate this thesis to my loving family. To my amazing husband, Hugo
L. Rodriguez, this work would not have been possible without your loving support
and patience. The strong work put into this research and thesis writing would not
have been possible without the guidance and encouragement to always follow
my dreams from that of my wonderful parents, Sonia Abolafia Bezares and David
Cruz-Wells.

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ACKNOWLEDGMENTS
I would also like to acknowledge the committee members, Drs. Charlotte
Brunner, Kevin Briggs and Vernon Asper, for their advice and guidance
throughout the entire length of the project. Additional thanks to Dr. Kevin Briggs
for the use of his macrofaunal data. To my major professor, Dr. Charlotte
Brunner, I would like to give enormous appreciation for her support and guidance
but most of all for the honor of accepting me into her lab where I was granted the
opportunity in working with what I enjoy most, the Foraminifera.
I would like to give a warm thank you to Dr. Kevin Yeager of the
Department of Earth and Environmental Sciences at the University of Kentucky
for the use of his sedimentary data and for his good humor aboard the R/V Cape
Hatteras. Special thanks go to Dr. Brad Rosenheim of the College of Marine
Science at the University of South Florida for the opportunity to join the CARTHE
cruise in the summer of 2012 and collect the pseudo-replicates at the Obs0 site.
Appreciation is also in order for Dr. Barun Sen Gupta and Lorene Smith of the
Department of Geology and Geophysics at Louisiana State University for
allowing the use of their foraminiferal collection. Acknowledgment must go to Dr.
J.T. Johnson for his statistical guidance. Deepest thanks to the lab technicians
(Logan Dedeaux, Candis Mallett, Carlo Fortner, Jennifer Brizzolara, and Joseph
Keim) and fellow students (Franklin Williams, Shivakumar Shivarudrappa, and
Sarah Epps) for their help and guidance with sampling, processing, and data
analysis.

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TABLE OF CONTENTS
ABSTRACT .......................................................................................................... ii
DEDICATION ...................................................................................................... iv
ACKNOWLEDGMENTS ....................................................................................... v
LIST OF TABLES ............................................................................................... vii
LIST OF ILLUSTRATIONS ................................................................................ viii
LIST OF ABBREVIATIONS ................................................................................ xii
CHAPTER
I. INTRODUCTION............................................................................ 1
Background
Objectives
Hypotheses
II. METHODOLOGY ......................................................................... 15
Coring and Sampling
Data Calculations and Analyses
III. RESULTS .................................................................................... 23
Physical Variables
Foraminiferal Density
Foraminiferal Assemblage
Foraminiferal Diversity Measures
Foraminiferal Opportunistic and/or Stress Tolerant Species
IV. DISCUSSION ............................................................................... 92
Examining the Hypotheses
Comparisons to Other’s Works
Comparison of Foraminiferal Trends with Macrofaunal Trends
Conclusion

APPENDIXES ................................................................................................. 116
REFERENCES .................................................................................................205
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LIST OF TABLES
Table
1. Physical Variables of GIP and Obs Sites ................................................ 24
2. Specimen Densities of All Surface Samples ........................................... 27
3. Measures of Central Tendency for Specimen Density ............................ 28
4. Specimen Densities of GIP 25 Downcore Samples................................. 31
5. Downcore DOH, Living Percentage, and Standing Stock ........................ 33
6. Specimen Densities of GIP 15 Downcore Samples................................. 34
7. Diversity Indices for All Surface Samples ................................................ 74
8. Measures of Central Tendency for S Index ............................................. 75
9. Measures of Central Tendency for H’ Index ............................................ 80
10. Measures of Central Tendency for D Index ............................................. 81
11. Measures of Central Tendency for J Index ............................................. 81
12. Diversity Indices for GIP 25’s Downcore Samples .................................. 83
13. Diversity Indices for GIP 15’s Downcore Samples .................................. 87

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LIST OF ILLUSTRATIONS
Figure
1. Point-Source Pollution Model .................................................................... 6
2. Site locations for this in the northern Gulf of Mexico ............................... 16
3. Whisker plot of specimen density versus sites ........................................ 27
4. Specimen density of surface samples from 2010 .................................... 29
5. Specimen density of surface samples from 2011 .................................... 29
6. Specimen density of the three pseudo-replicates .................................... 30
7. Specimen density for downcore samples at GIP 25 (2010) ..................... 32
8. Specimen density for downcore samples at GIP 25 (2011) ..................... 32
9. Specimen density for downcore samples at GIP 15 (2010) ..................... 35
10. Specimen density for downcore samples at GIP 15 (2011) ..................... 35
11. Relative Frequency of Suborders from Obs0 .......................................... 38
12. Relative Frequency of Suborders from 2010 surface Samples ............... 39
13. Relative Frequency of Suborders from 2011 surface Samples ............... 40
14. Relative Frequency of Suborders from GIP25 downcore samples
(2010) ..................................................................................................... 41

15. Relative Frequency of Suborders from GIP25 downcore samples
(2011) .................................................................................................... 42

16. Relative Frequency of Suborders from GIP15 downcore samples
(2010) ..................................................................................................... 43

17. Relative Frequency of Suborders from GIP15 downcore samples
(2011) .................................................................................................... 44

18. Species with relative frequencies > 5% at Obs0 ..................................... 45
19. Species with relative frequencies > 5% for Surface Samples (2010) ...... 47
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20. Species with relative frequencies > 5% for Surface Samples (2011) ...... 48
21. Species with relative frequencies > 5% from GIP25 downcore samples
(2010) ..................................................................................................... 49

22. Species with relative frequencies > 5% from GIP25 downcore samples
(2011) ..................................................................................................... 50

23. Species with relative frequencies > 5% from GIP15 downcore samples
(2010) ..................................................................................................... 51

24. Species with relative frequencies > 5% from GIP15 downcore samples
(2011) ..................................................................................................... 52

25. Juvenile distribution for all surface samples ............................................ 54
26. Relative frequencies of juveniles present at Obs0 .................................. 55
27. Relative frequencies of juveniles present in all surface samples (2010) .. 56
28. Relative frequencies of juveniles present in all surface samples (2011) .. 57
29. Juvenile distribution for all downcore samples at GIP 25 and 15 ............ 59
30. Relative frequencies of juveniles present in GIP 25 downcore samples
(2010) ..................................................................................................... 59

31. Relative frequencies of juveniles present in GIP 25 downcore samples
(2011) ..................................................................................................... 61

32. Relative frequencies of juveniles in GIP 15 downcore samples (2010) ... 62
33. Relative frequencies of juveniles in GIP 15 downcore samples (2011) ... 63
34. MDS of all surface samples .................................................................... 64
35. Dendrogram of the Q-mode cluster analysis of all surface samples ........ 66
36. MDS of all downcore samples at GIP 25 and 15 ..................................... 67
37. Dendrogram of clusters for all downcore samples at GIP 25 and 15 ....... 68
38. MDS interpretation of the surface samples ............................................. 69
39. MDS interpretation of the downcore samples at GIP 25 and 15 .............. 70
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