Preliminary Paleontologic Report on Cores 19A and 19B,

from Russell Bank, Everglades National Park,

Florida Bay

by

G.L. Brewster-Wingard1, S.E. Ishman1, D.A. Willard1, L.E. Edwards1, and C.W. Holmes2

1 U.S. Geological Survey, Reston, VA

2

 U.S. Geological Survey, St. Petersburg, FL

Open-File Report 97-460

This report is preliminary and has not been reviewed for conformity with U.S. Geological Survey editorial standards

or with the North American Stratigraphic Code. Any use of trade, product, or firm names is for descriptive purposes

only and does not imply endorsement by the U.S. Government

1997
TABLE OF CONTENTS

Abstract

Introduction

Acknowledgments

Methods of Investigation

 Benthic Foraminifers and Molluscs

 Pollen and Dinocysts

 Isotopic Analyses

Analysis and discussion of the benthic fauna in core 19B

 Benthic Foraminifers

 Molluscs

 Benthic Faunal Patterns

Analysis and discussion of the flora in core 19A

 Pollen

 Dinocysts

 Floral Patterns

210Pb age model for the Russell Bank site

Summary

References Cited

FIGURES

1. Location map of Russell Bank

2. Cluster diagram of molluscan assemblages

3. Plot of percent abundance of benthic faunal indicators of marine salinity

4. Plot of percent abundance of molluscan substrate indicators

5. Plot of percent abundance of pollen taxa

6. Actual counts of pollen grains

7. Plot of percent and absolute abundances of dinocysts

8. Plot of absolute abundances of Polysphaeridium zoharyi and Spiniferites

9. 210Pb activity for core 19B

10. 210Pb activity for core 19C

TABLES

1. Russell Bank 19B: Percent abundance of benthic foraminifera

2. Russell Bank 19B: Percent abundance of molluscan fauna

3. Russell Bank 19A: Percent abundance of pollen

4. Dinocyst data from Russell Bank 19A
Preliminary Paleontologic Report on Cores 19A and 19B, from Russell Bank,

Everglades National Park, Florida Bay

ABSTRACT

 The fauna and flora preserved in two cores, 19A and 19B, from the south side of Russell Bank

(N 25 03.831’, W 80 37.486’) in north-central Florida Bay, Everglades National

Park, Florida, record a history of environmental change over the last century. The benthic

foraminifera and molluscs indicate fluctuating salinities with increasing average salinity upcore

in core 19B. Shifts from low salinity (12-15 ppt) to higher average salinity (30 ppt) occurred at

70-66 cm and 24-18 cm in core 19B (approximately 1937-1940 and 1975-1980). The inverse,

shifts from periods of higher average salinity to periods of lower salinity, occurred at 140 cm, 90

cm, and 42 cm (approximately 1880, 1921, and 1960). Significant changes in the molluscan

fauna indicative of specific substrate types occur at 88 cm, 68 cm, and 22 cm. The lower portion

of the core is dominated by a mixture of sediment and grass dwellers, the middle portion by

sediment dwellers, and the upper portion of the core by grass and finally grass and algae

dwellers. Changes occur in the floral assemblages in core 19A, but the significance of these

changes is unclear. Three subtle shifts occur in the pollen assemblages indicating the onshore

vegetation was responding to some environmental factor. Two peaks in dinocyst abundance

occur in core 19A, but the composition of dinocyst assemblages remains relatively stable

throughout the core. Correspondence between changes in salinity and onshore vegetation

changes is consistent with results from previous cores. The pattern of increased salinity upcore is

consistent with patterns seen in core T24 from the mouth of Taylor Creek and in core 6A from

Bob Allen mudbank.

INTRODUCTION

 The fragile and unique ecosystems of southern Florida, including Florida Bay, the terrestrial

Everglades, and Biscayne Bay, have been the focus of a substantial scientific effort in response

to environmental, economic and political concerns. These concerns are focused on returning the

Everglades to its "natural state" as mandated by the Everglades Forever Act (passed in 1994),

while at the same time addressing the conflicting interests of the ever-growing population of

southern Florida, the environmentalists, the farmers, and the tourist industry, among others.

Consequently, Federal, State, and local jurisdictions are faced with decisions related to the

ecosystem restoration goals, mediation of conflicting interests, and monitoring of change.

 An essential part of the decision making process is to understand the history of the ecosystem

prior to significant human alteration, and to separate natural variability in the ecosystem from

human-induced change. The U.S. Geological Survey (USGS), in cooperation with National

Oceanic and Atmospheric Administration (NOAA), South Florida Water Management District

(SFWMD), the National Park Service (NPS), the Army Corps of Engineers (ACOE), and other

Federal, State and local agencies, is conducting research to provide information on the history of
the Everglades ecosystem over the last 150-200 years. The distribution of fauna and flora in a

series of sediment cores taken throughout the Everglades ecosystem provides information on the

biological, physical and chemical parameters of the system over time.

 Sediment cores were taken in February of 1995 by researchers from the U.S. Geological

Survey (St. Petersburg, FL), in cooperation with South Florida Water Management District

(SFWMD) and the Everglades National Park (ENP), for use by USGS investigators conducting

research in Florida Bay. Three cores were taken from the south side of Russell Bank (N 25

03.831’, W 80 37.486’) in north-central Florida Bay (Figure 1). Cores 19A and 19B are

replicate cores, taken side by side from a grass bed in 0.51 m of water. Core 19C was taken 54 m

north of 19A and 19B from a mud flat, on top of the south side of Russell Bank. Core 19A

penetrated 140 cm of sediment, spanning approximately 115 years, and has been sampled for

210Pb and palynologic analyses. Core 19B penetrated 144 cm of sediment, spanning

approximately 118 years, and has been sampled for 210Pb and calcareous fossil analyses. Core

19C penetrated 158 cm of sediment and has been sampled for 210Pb analysis.

 This report is produced by the "Ecosystem History of Florida Bay and the Southwest Coast"

component of the U.S. Geological Survey’s Ecosystem Program, and is one of a series of USGS

Open-File Reports on the distribution of biogenic components in sediments sampled from the

southern Florida region. The data presented in these reports can be used to estimate changes in

salinity, substrate, and other critical components of the ecosystem over time.

ACKNOWLEDGMENTS

 We would like to thank Robert Halley and Gene Shinn, U.S. Geological Survey, St.

Petersburg, FL, for collecting the cores and making them available to us for analysis. We would

like to thank our colleagues at South Florida Water Management District, National Oceanic and

Atmospheric Administration, and Everglades National Park for their cooperation and assistance

in this investigation. We have benefited from discussions with William Lyons, Florida Marine

Research Institute, St. Petersburg, FL; and Thomas Scott, Florida Geological Survey,

Tallahassee, FL. Our reviewers, Thomas Cronin and John Sutter, U.S. Geological Survey,

Reston, VA, provided helpful comments and suggestions to improve this manuscript.

 Marci Marot, U.S. Geological Survey, St. Petersburg, FL, prepared the samples for isotopic

and calcareous analysis. Assistance in sample processing was provided by Jill D’Ambrosio, Ian

Graham, Lisa Weimer, Neil Waibel, Patrick Buchanan, Nancy Carlin, and Steve Wandrei of the

U.S. Geological Survey, Reston, VA. Rob Stamm and Patrick Buchanan, U.S. Geological

Survey, Reston, VA, assisted in the preparation of illustrations for this report and Jill

D’Ambrosio assisted in compiling the final report.
8

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JOHN PENNEKAMP

CORAL REEF

STATE PARK

ONAL

1

20
METHODS OF INVESTIGATION

Benthic Foraminifers and Molluscs

 Sediment samples from core 19B were collected at 2 cm intervals and every other sample,

starting with 0-2 cm and totaling 34 samples, was analyzed for calcareous benthic fauna. The

samples were washed through a 63μ m sieve and dried at <50 degrees C. When possible, a total of

300 benthic foraminifer specimens were picked from the sample and mounted on gridded

micropaleontologic slides. Large samples were put through a sample splitter to randomly reduce

the number of specimens. For samples containing fewer than 300 benthic foraminifer

individuals, all of the specimens present were picked. Molluscs were picked from the > =

850μ m size fraction. All molluscs, and fragments of molluscs recognizable to the generic level,

present in each interval were picked. Species abundances for the benthic fauna were standardized

by calculating relative abundances (percent).

Pollen and Dinocysts

 Material for palynological analysis was extracted from 1-2 cm sections of core 19A. For each

palynological sample, 7-40 g of material (dry weight) was treated in hydrochloric and

hydrofluoric acids and processed for palynological studies. All samples were treated with warm

KOH for 2-5 minutes, given ultrasonic pulse treatment for 5 seconds, acetolysed, and sieved

between 8-200μ m mesh. A tablet of Lycopodium marker grains was added to each sample. For

most samples, at least 300 pollen grains were counted for calculation of percent abundances and

absolute pollen concentration. To calculate absolute concentration of palynomorphs, the markergrain method was used (Benninghoff, 1962; Maker, 1981, Stockmarr, 1971). For two samples,

pollen was sparse enough that fewer than 300 grains were counted. For nine samples, one slide

was completely examined for dinocysts and all dinocyst taxa were tabulated. For two samples (0-

1 cm and 80-82 cm), two slides were examined completely for dinocysts.

Isotopic Analyses

 Samples were collected every 2 cm from cores 19B and 19C and analyzed for 210Pb, Ra,

137Ce, 7

Be, and total Pb. Analysis of 210Pb has been completed for 19B and Ra and 210Pb have

been completed for 19C. For details of the method see Robbins et al. (in press).
ANALYSIS AND DISCUSSION OF THE BENTHIC FAUNA IN CORE 19B

Benthic Foraminifers

 A total of 31 benthic foraminiferal species were identified and counted. The foraminiferal data

was standardized to relative abundance (percent of assemblage; Table 1) and was used for all

quantitative analyses. Species diversity as measured by Simpson’s Index ranged from 0.11 to

0.26, and the number of species ranged from 12 to 19.

 The foraminiferal assemblages are dominated by calcareous benthic forms with the

dominance patterns alternating between rotaliid taxa, Ammonia parkinsoniana tepida, A.

parkinsoniana typica, Elphidium galvestonense mexicanum, E. galvestonense typica, and E.

poeyanum; and miliolid taxa, Miliolinella cirlcularis, M. labiosa, Quinqueloculina bosciana, Q.

seminulum, Q. tenagos, Q. polygona, Q. poeyana, and Triloculina tricarinata. Other significant

species include Archaias angulatus, Peneroplis proteus, Rosalina floridana and Quinqueloculina

agglutinans.

 Two dominant assemblages can be identified in the cores, an Ammonia-Elphidium (A-E)

assemblage and a miliolid assemblage. Observations of the foraminiferal faunal changes

throughout core 19B show four intervals dominated by the miliolid assemblage (140 cm, 118-90

cm, 70-42 cm, and 18-0 cm), interrupted by three intervals of A-E assemblage dominance (140-

118 cm, 90-70 cm, and 42-18 cm).

Molluscs

 Twenty-six molluscan taxonomic categories were recognized and counted in the Russell Bank

19B core. The number of specimens per sample ranged from 2 to 517, so the faunal counts were

standardized to relative percent abundance (Table 2). The Simpson’s Diversity Index was

calculated for each sample (Table 2). Three sections in the core contained few individual

specimens (<40), and few molluscan taxonomic groups (1-9): 122-112cm, 62-52cm, 38-28cm.

Two species, Brachiodontes sp. and Transennella sp. make up greater than 50 percent of the

molluscan fauna in the entire core.

 A cluster analysis of Pearsons Correlation coefficient values, calculated for the molluscan

percent abundance data and plotted using average linkage method (Figure 2), revealed 3 primary

divisions of the molluscan assemblages within the core: 142-68 cm, 68-22 cm, and 22-0 cm. The

interval from 142-68 cm is dominated by Transennella sp., Brachiodontes sp., and Cerithium

spp.; Bittium varium, Rissoina spp., and Chione cancellata also are present in significant

amounts (5%) throughout the interval. The interval from 66-22 cm has the lowest within-group

similarity of the three molluscan assemblages in the core and is represented by 2 clusters in the

anlaysis. This interval from 66-22 cm contains 2 zones of very low molluscan abundance (62-52

cm and 38-28 cm). Brachiodontes sp. and Cerithium spp. dominate the 66-22 cm interval, with a

number of other species present in significant amounts (10%) in individual samples (see Table
Table 1

Russell Bank 19B

Percent Abundance of Benthic Foraminifera

Depth in Core

Ammonia parkinsoniana tepidaAmmonia parkinsoniana typicaArchaias angulatusBolivina lowmaniBolivina pseudoplicataClavulina tricarinataCyclogyra planorbisElphidium delicatulumElphidium galvestonense typicumElphidium galvestonense mexicanumElphidium poeyanumGrass dwellerMiliolinella circularisMiliolinella fichtelianaMiliolinella labiosaNodosariidaePeneroplis proteusQuinqueloculina agglutinansQuinqueloculina bosciana

0-2 cm 0.00 1.07 0.00 0.00 0.00 0.00 0.00 0.00 11.23 1.07 0.00 0.80 12.03 0.00 0.00 0.00 0.27 0.00 17.91

4-6 cm 0.00 0.98 1.64 0.00 0.00 0.00 0.00 0.00 9.18 3.28 0.00 0.33 7.87 0.00 0.00 0.00 0.00 0.66 14.43

8-10 cm 0.00 5.23 0.00 0.00 0.00 0.00 0.00 0.00 14.63 4.18 0.00 0.70 5.92 0.00 0.00 0.00 0.70 0.00 16.72

12-14 cm 0.00 6.42 5.20 0.00 0.00 0.00 0.00 0.00 8.87 13.76 0.00 0.00 6.73 0.00 0.31 0.00 0.92 0.61 7.65

16-18 cm 0.00 7.61 5.43 0.00 0.00 0.00 0.00 0.00 21.74 19.57 0.00 0.00 5.43 0.00 0.00 0.00 0.00 3.26 5.43

24-26 cm 0.00 8.88 1.64 0.00 0.00 0.00 0.00 0.00 5.59 10.86 0.00 0.66 3.29 0.33 0.00 0.00 0.66 3.95 21.71

28-30 cm 0.00 17.38 0.66 0.00 0.00 0.00 0.00 0.00 17.70 27.87 0.00 0.33 4.92 0.00 0.00 0.33 0.33 0.00 4.59

32-34 cm 0.00 12.94 1.29 0.00 0.00 0.00 0.00 0.00 19.74 19.09 0.00 0.00 3.88 0.00 0.00 0.00 0.00 0.00 30.10

36-38 cm 0.00 23.47 1.44 0.00 0.00 0.00 0.72 0.00 10.11 12.27 0.00 0.72 2.17 0.72 0.00 0.00 0.00 0.72 24.55

40-42 cm 0.00 5.56 0.65 0.00 0.00 0.00 0.65 0.00 12.42 0.00 0.00 1.96 7.52 0.00 0.00 0.00 0.00 0.33 35.62

44-46 cm 0.00 5.25 0.31 0.00 0.00 0.00 0.93 0.00 12.65 5.56 0.00 1.54 7.41 0.00 0.00 0.00 0.00 1.85 25.62

48-50 cm 0.00 9.94 0.00 0.00 0.29 0.00 0.29 0.00 0.00 31.29 0.00 1.75 2.92 0.00 0.00 0.00 0.00 0.29 24.27

52-54 cm 0.00 6.64 0.00 0.35 0.00 0.00 1.40 0.00 13.64 6.99 0.00 3.85 6.99 0.00 0.00 0.00 0.00 0.00 25.52

56-58 cm 0.00 2.81 1.12 0.00 0.00 0.00 0.56 0.00 11.80 5.34 0.00 8.71 9.27 0.00 0.00 0.00 0.00 0.56 23.88

60-62 cm 0.00 9.75 1.44 0.00 0.00 0.00 0.36 0.00 9.03 17.33 0.00 3.25 7.22 0.00 0.00 0.00 0.00 0.72 22.74

64-66 cm 0.00 7.67 1.84 0.00 0.00 0.31 0.61 0.00 7.06 16.26 0.00 2.76 7.36 0.00 0.00 0.00 0.61 1.23 14.42

68-70 cm 0.00 15.36 0.31 0.00 0.00 0.63 0.00 0.00 9.72 31.03 0.00 0.63 13.48 0.00 0.00 0.00 0.00 0.00 4.39

72-74 cm 0.00 16.91 3.44 0.00 0.00 0.00 0.00 0.00 12.61 24.36 0.00 0.86 8.02 0.00 0.00 0.00 0.00 1.15 8.60

76-78 cm 0.00 14.67 3.67 0.00 0.00 0.00 0.00 0.00 9.00 37.67 0.00 0.00 5.00 0.00 0.67 0.00 0.00 0.00 2.67

80-82 cm 0.00 19.21 2.13 0.00 0.00 0.00 0.00 0.00 7.93 39.94 0.00 0.00 2.13 0.00 0.00 0.00 0.00 1.22 0.30

84-86 cm 0.00 20.97 0.32 0.00 0.00 0.00 0.00 0.00 8.06 34.19 11.29 0.00 2.26 0.00 0.00 0.00 0.00 0.00 1.61

88-90 cm 0.00 18.64 0.34 0.00 0.00 0.00 0.00 0.00 0.00 39.32 11.53 0.00 2.37 0.00 0.00 0.00 0.34 0.34 1.02

92-94 cm 0.00 3.29 0.33 0.00 0.00 0.00 0.00 0.00 7.57 12.17 23.03 0.00 9.21 0.00 0.00 0.00 0.00 0.33 7.89

96-98 cm 0.00 5.38 0.28 0.00 0.00 0.00 0.00 27.20 6.52 11.33 0.00 0.00 7.37 0.00 0.00 0.00 0.00 0.00 14.16

100-102 cm 0.00 11.48 0.33 0.00 0.00 0.00 0.00 22.30 0.00 25.90 0.00 0.00 5.90 0.00 0.00 0.00 0.00 0.00 2.95

104-106 cm 0.00 6.35 1.59 0.00 0.00 0.00 0.00 20.32 3.17 13.33 0.00 0.00 7.94 0.00 0.00 0.00 0.63 1.27 15.56

108-110 cm 0.00 16.55 3.38 0.00 0.00 0.00 0.00 4.39 2.70 26.01 0.00 0.00 12.50 0.68 0.00 0.00 0.00 3.38 0.00

112-114 cm 0.80 4.79 1.33 0.00 0.00 0.00 0.00 0.00 17.29 10.64 0.00 0.00 15.96 0.27 0.00 0.00 0.53 1.33 19.41

116-118 cm 0.00 11.81 1.39 0.00 0.00 0.00 0.00 0.00 28.47 20.14 0.00 0.00 9.72 0.00 0.00 0.00 0.00 0.00 2.43

120-122 cm 0.00 17.61 0.66 0.00 0.00 0.00 0.00 0.00 20.93 22.92 0.00 0.00 5.32 0.00 0.00 0.00 0.00 0.66 0.00

124-126 cm 0.00 31.42 4.53 0.00 0.00 0.60 0.00 1.21 0.00 43.50 0.00 0.00 2.42 0.00 0.00 0.00 0.00 2.42 0.00

128-130 cm 0.00 27.86 3.52 0.00 0.00 0.00 0.00 5.28 0.00 41.64 0.00 0.00 5.87 0.00 0.00 0.00 0.00 4.11 0.29

132-134 cm 0.00 17.05 1.29 0.00 0.00 0.00 0.00 9.04 2.33 31.78 0.00 0.00 9.56 0.00 0.00 0.00 0.00 0.52 3.10

136-138 cm 0.00 8.43 4.21 0.00 0.00 0.00 0.00 8.99 3.93 12.36 0.00 0.00 24.44 0.00 0.28 0.00 0.84 1.97 4.49

140-142 cm 0.00 20.32 5.81 0.00 0.00 0.00 0.00 0.00 6.45 39.03 0.00 0.00 6.45 0.00 0.00 0.00 0.00 2.90 0.00
Table 1

Russell Bank 19B

Percent Abundance of Benthic Foraminifera

Depth in Core

0-2 cm 

4-6 cm 

8-10 cm 

12-14 cm 

16-18 cm 

24-26 cm 

28-30 cm 

32-34 cm 

36-38 cm 

40-42 cm 

44-46 cm 

48-50 cm 

52-54 cm 

56-58 cm 

60-62 cm 

64-66 cm 

68-70 cm 

72-74 cm 

76-78 cm 

80-82 cm 

84-86 cm 

88-90 cm 

92-94 cm 

96-98 cm 

100-102 cm 

104-106 cm 

108-110 cm 

112-114 cm 

116-118 cm 

120-122 cm 

124-126 cm 

128-130 cm 

132-134 cm 

136-138 cm 

140-142 cm 

Quinqueloculina seminulumQuinqueloculina tenagosQuinqueloculina polygonaQuinqueloculina poeyanaRosalina floridanaRosalina globularisSpiroloculina antillariumTriloculina lineianaTriloculina rotundaTriloculina triloculinaValvulina sp.Valvulineria laevigataNumber of Species Simpson's Diversity Index

13.37 1.07 4.81 32.35 2.14 0.00 0.27 0.00 0.00 1.60 0.00 0.00 14 0.19

5.25 0.00 12.79 39.34 0.66 0.00 0.98 0.00 0.00 2.62 0.00 0.00 14 0.21

7.32 2.79 2.44 32.75 0.35 0.00 0.00 0.00 0.00 6.27 0.00 0.00 13 0.18

3.67 1.53 2.14 28.75 0.92 0.00 0.00 0.00 0.31 10.09 0.00 2.14 17 0.14

2.17 0.00 6.52 14.13 0.00 0.00 1.09 0.00 0.00 7.61 0.00 0.00 12 0.13

2.30 9.54 6.91 14.80 0.99 0.00 0.00 0.00 4.93 1.64 0.00 1.32 18 0.11

8.85 0.00 3.93 10.82 2.30 0.00 0.00 0.00 0.00 0.00 0.00 0.00 13 0.17

0.00 0.00 6.47 5.83 0.65 0.00 0.00 0.00 0.00 0.00 0.00 0.00 9 0.19

0.72 2.89 2.17 13.72 0.00 0.00 0.00 0.00 2.17 1.08 0.36 0.00 17 0.16

10.46 1.63 1.63 19.93 0.65 0.00 0.00 0.00 0.65 0.00 0.00 0.33 15 0.20

6.48 3.40 3.70 23.77 1.54 0.00 0.00 0.00 0.00 0.00 0.00 0.00 14 0.16

3.22 1.75 1.17 16.37 2.05 0.00 0.00 0.00 2.05 2.34 0.00 0.00 15 0.20

2.45 1.40 0.00 27.97 1.40 0.00 0.00 0.00 0.00 1.40 0.00 0.00 13 0.18

3.65 0.00 1.69 26.69 0.56 0.00 0.00 0.00 0.00 3.37 0.00 0.00 14 0.16

10.11 1.81 3.97 12.27 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 13 0.13

5.21 2.15 7.06 19.33 2.45 0.00 0.00 0.00 1.23 2.15 0.00 0.31 19 0.11

8.78 0.00 0.00 13.17 2.19 0.00 0.00 0.00 0.00 0.31 0.00 0.00 12 0.18

2.01 0.86 4.01 11.46 1.15 0.00 0.00 0.00 0.00 4.01 0.00 0.57 15 0.14

6.67 0.00 4.67 11.00 1.33 0.00 0.00 0.00 0.00 2.67 0.00 0.33 13 0.20

5.49 0.00 6.71 7.32 0.00 0.00 0.00 0.00 2.13 4.88 0.00 0.61 13 0.22

2.90 0.00 0.32 15.16 0.00 0.00 0.00 0.00 0.97 1.94 0.00 0.00 12 0.21

8.81 0.00 5.08 7.80 0.00 0.00 0.00 0.00 1.36 2.71 0.00 0.34 14 0.22

19.08 0.99 2.96 11.84 1.32 0.00 0.00 0.00 0.00 0.00 0.00 0.00 13 0.14

8.78 0.00 2.27 10.20 1.70 0.00 1.42 0.00 3.40 0.00 0.00 0.00 13 0.14

15.41 0.00 4.26 7.87 0.33 0.00 0.66 0.00 1.97 0.66 0.00 0.00 13 0.17

12.38 0.00 2.22 13.97 0.95 0.32 0.00 0.00 0.00 0.00 0.00 0.00 14 0.13

10.14 0.34 5.74 7.77 0.00 0.00 0.00 0.00 2.36 3.38 0.00 0.68 15 0.14

9.84 0.00 2.93 10.11 2.13 0.00 0.00 0.00 1.33 0.80 0.00 0.53 17 0.13

16.32 1.04 2.08 4.86 0.35 0.00 0.00 0.00 0.35 1.04 0.00 0.00 13 0.18

20.93 0.00 1.66 5.65 1.00 0.00 0.00 0.00 0.33 1.00 1.33 0.00 13 0.18

0.00 2.72 2.42 3.93 0.00 0.00 0.00 0.30 0.91 3.63 0.00 0.00 13 0.30

0.00 0.29 2.35 3.23 0.29 0.00 0.00 0.00 0.59 4.11 0.00 0.59 14 0.26

11.11 0.00 2.07 6.20 0.52 0.00 0.00 0.00 3.36 2.07 0.00 0.00 14 0.17

9.83 1.40 2.53 9.55 1.69 0.00 0.00 0.00 1.12 2.53 0.00 1.40 18 0.12

2.58 0.32 4.19 5.48 0.00 0.00 0.65 0.00 0.65 2.58 0.00 2.58 14 0.21
Table 2

Russell Bank 19B

Percent Abundance of Molluscan Fauna

Depth in 

Core

GastropodsActeocina canaliculataAmaea spp.Bittium variumBulla sp.Caecum puchellum/floridanumCerithidea spp.Cerithium spp.Conus sp.Crepidula sp.MarginellidsModulus modulusOlivella sp.Rissoina spp.Turritella exoletaVitrinellidsRare Gastropods

Unidentified gastropod fragments, unknown sp., and juveniles

0-2 cm 0.00 0.00 1.28 0.00 1.47 0.00 5.68 0.00 0.73 0.92 1.83 0.00 2.20 0.00 0.37 0.37 0.55

4-6 cm 0.00 0.00 3.47 0.00 0.87 0.00 7.23 0.00 1.16 1.16 3.47 0.00 1.45 0.00 1.16 1.16 2.60

8-10 cm 0.00 0.00 1.72 0.00 0.00 0.00 2.59 0.00 0.00 0.86 5.17 0.00 3.45 0.00 3.45 0.86 3.45

12-14 cm 0.00 0.00 2.44 0.00 2.44 0.00 4.88 0.00 0.00 0.61 2.44 2.44 4.88 2.44 0.00 0.61 3.66

16-18 cm 0.00 0.00 2.44 0.00 0.00 0.00 6.10 0.00 1.22 0.00 1.22 1.22 8.54 0.00 0.00 1.22 3.66

20-22 cm 0.00 0.00 2.70 1.35 1.35 0.00 2.70 0.00 1.35 0.00 0.00 0.00 1.35 0.00 0.00 1.35 2.70

24-26 cm 1.72 0.00 3.45 0.00 3.45 1.72 15.52 0.00 6.90 0.00 0.00 1.72 1.72 0.00 0.00 0.00 1.72

28-30 cm 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00

32-34 cm 0.00 0.00 7.14 7.14 0.00 0.00 21.43 0.00 0.00 0.00 7.14 0.00 7.14 0.00 0.00 0.00 0.00

36-38 cm 0.00 0.00 21.43 0.00 0.00 0.00 35.71 3.57 0.00 0.00 3.57 10.71 0.00 0.00 0.00 0.00 10.71

40-42 cm 0.00 0.00 12.37 5.15 0.00 0.00 18.56 0.00 3.09 0.00 1.03 2.06 4.12 0.00 0.00 1.03 4.12

44-46 cm 0.00 0.00 2.15 0.00 0.00 0.00 8.60 0.00 0.00 0.00 6.45 1.08 9.68 0.00 1.08 0.00 4.30

48-50 cm 0.00 0.00 11.11 0.00 0.00 0.00 18.52 0.00 0.00 0.00 5.56 0.00 7.41 0.00 0.00 0.00 7.41

52-54 cm 0.00 0.00 0.00 0.00 0.00 0.00 8.11 0.00 0.00 0.00 43.24 0.00 2.70 0.00 0.00 0.00 5.41

56-58 cm 0.00 0.00 0.00 0.00 10.00 0.00 40.00 0.00 40.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00

60-62 cm 0.00 0.00 3.13 0.00 0.00 0.00 0.00 6.25 0.00 0.00 0.00 0.00 6.25 0.00 0.00 3.13 18.75

64-66 cm 0.00 0.00 8.00 2.00 1.00 0.00 14.00 0.00 3.00 1.00 2.00 0.00 3.00 0.00 0.00 0.00 4.00

68-70 cm 0.00 0.00 15.69 0.00 1.96 0.00 17.65 0.00 3.92 1.96 1.96 0.00 9.80 0.00 0.00 3.92 5.88

72-74 cm 0.00 0.00 19.18 0.00 1.37 0.00 19.18 0.00 6.85 0.00 1.37 0.00 0.00 0.00 0.00 0.00 5.48

76-78 cm 0.00 0.00 5.62 0.00 0.00 0.00 11.24 0.00 0.00 5.62 3.37 2.25 5.62 1.12 0.00 0.00 16.85

80-82 cm 0.00 0.00 4.14 0.00 0.00 0.00 5.52 0.00 0.00 1.38 0.69 1.38 0.00 1.38 0.00 0.00 9.66

84-86 cm 0.00 0.00 9.33 0.00 4.00 0.00 13.33 2.67 1.33 0.00 2.67 2.67 5.33 0.00 0.00 0.00 13.33

88-90 cm 0.00 0.00 2.19 0.00 0.00 0.00 16.06 0.00 0.00 0.00 0.00 2.92 8.03 2.19 0.00 1.46 15.33

92-94 cm 0.00 0.00 4.32 0.00 1.44 0.00 10.07 0.00 0.00 0.00 0.72 2.88 5.04 1.44 0.00 0.00 9.35

96-98 cm 3.03 0.00 1.52 0.00 1.52 0.00 13.64 0.00 1.52 0.00 0.00 1.52 7.58 1.52 0.00 3.03 1.52

100-102 cm 0.00 0.00 0.00 0.00 1.38 0.00 4.83 0.00 0.00 0.69 0.00 2.07 3.45 0.00 0.00 0.00 4.83

104-106 cm 0.00 0.67 7.38 0.00 0.67 1.34 16.11 0.67 0.00 1.34 0.00 1.34 4.70 0.67 0.00 1.34 4.70

108-110 cm 0.00 2.38 7.14 0.00 0.00 0.00 9.52 0.00 0.00 0.79 0.00 3.97 11.90 0.79 0.00 1.59 18.25

112-114 cm 2.86 0.00 8.57 0.00 0.00 0.00 17.14 0.00 2.86 0.00 2.86 0.00 0.00 0.00 0.00 0.00 11.43

116-118 cm 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 20.00

120-122 cm 0.00 0.00 3.45 0.00 3.45 0.00 6.90 0.00 0.00 0.00 0.00 3.45 6.90 10.34 0.00 0.00 3.45

124-126 cm 0.75 0.00 9.70 0.00 0.00 1.49 13.43 0.00 0.75 0.00 8.21 2.24 3.73 1.49 1.49 1.49 2.24

128-130 cm 0.00 1.43 2.57 0.00 0.86 0.00 8.57 0.00 1.14 0.86 0.86 0.00 2.86 0.29 0.00 0.29 5.71

132-134 cm 0.00 0.00 7.23 0.00 0.00 0.00 12.05 0.00 0.00 0.00 0.00 1.20 4.82 6.02 0.00 0.00 10.84

136-138 cm 0.51 0.51 7.69 0.51 1.03 1.03 6.15 0.00 0.00 1.03 0.00 1.03 0.00 2.56 1.03 2.56 4.10

140-142 cm 0.55 0.00 6.56 0.00 0.00 0.00 7.10 0.55 1.09 0.00 0.00 3.83 6.01 1.09 0.00 0.00 8.74
Table 2

Russell Bank 19B

Percent Abundance of Molluscan Fauna

Depth in 

Core

0-2 cm 

4-6 cm 

8-10 cm 

12-14 cm 

16-18 cm 

20-22 cm 

24-26 cm 

28-30 cm 

32-34 cm 

36-38 cm 

40-42 cm 

44-46 cm 

48-50 cm 

52-54 cm 

56-58 cm 

60-62 cm 

64-66 cm 

68-70 cm 

72-74 cm 

76-78 cm 

80-82 cm 

84-86 cm 

88-90 cm 

92-94 cm 

96-98 cm 

100-102 cm 

104-106 cm 

108-110 cm 

112-114 cm 

116-118 cm 

120-122 cm 

124-126 cm 

128-130 cm 

132-134 cm 

136-138 cm 

140-142 cm 

PelecypodsAnomalocardia sp.Arcopsis adamsiBrachiodontes sp.Chione cancellataCumingia tellinoideaLaevecardium spp.Nucula proximaPectinid Pinctada radiataTellina spp.Transennella spp.Rare PelecypodsUnidentified Pelecy. Frags.Total number of individual specimensNumber of faunal groupsSimpsons Diversity Index

0.00 0.18 70.33 0.73 0.55 0.00 0.00 0.00 12.64 0.00 0.00 0.18 0.00 517 16 0.52

0.00 1.16 64.16 0.87 0.00 0.00 0.00 0.00 9.54 0.00 0.00 0.29 0.29 331 16 0.43

0.00 0.00 73.28 0.86 0.00 0.00 0.00 0.00 2.59 0.00 0.00 0.00 1.72 49 12 0.55

0.00 1.83 57.32 2.44 0.61 0.00 0.00 0.00 10.37 0.00 0.00 0.00 0.61 145 16 0.35

0.00 0.00 57.32 3.66 1.22 0.00 0.00 0.00 2.44 0.00 7.32 0.00 2.44 62 14 0.35

0.00 0.00 77.03 0.00 0.00 0.00 0.00 0.00 0.00 0.00 2.70 0.00 5.41 62 11 0.60

0.00 0.00 24.14 3.45 0.00 1.72 0.00 0.00 1.72 1.72 17.24 0.00 12.07 50 16 0.14

0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 50.00 0.00 50.00 2 2 0.50

0.00 0.00 14.29 14.29 0.00 0.00 0.00 0.00 0.00 0.00 21.43 0.00 0.00 12 8 0.15

0.00 0.00 14.29 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 28 7 0.22

0.00 1.03 41.24 3.09 0.00 0.00 0.00 1.03 2.06 0.00 0.00 0.00 0.00 97 14 0.23

0.00 4.30 9.68 46.24 1.08 0.00 0.00 0.00 0.00 1.08 0.00 0.00 4.30 93 13 0.25

0.00 9.26 9.26 3.70 9.26 0.00 0.00 1.85 9.26 3.70 0.00 0.00 3.70 54 13 0.10

0.00 0.00 27.03 0.00 2.70 0.00 0.00 0.00 8.11 0.00 0.00 0.00 2.70 37 8 0.28

0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 10.00 10 4 0.34

0.00 0.00 50.00 0.00 0.00 3.13 0.00 0.00 3.13 0.00 0.00 0.00 6.25 32 9 0.30

0.00 0.00 29.00 1.00 0.00 1.00 0.00 10.00 9.00 2.00 3.00 1.00 6.00 100 18 0.14

0.00 0.00 5.88 5.88 1.96 0.00 0.00 1.96 0.00 0.00 9.80 0.00 11.76 51 15 0.10

0.00 0.00 19.18 5.48 0.00 0.00 2.74 0.00 0.00 0.00 19.18 0.00 0.00 73 10 0.16

0.00 1.12 19.10 0.00 0.00 0.00 0.00 0.00 3.37 0.00 7.87 0.00 16.85 89 13 0.12

0.00 2.07 26.90 8.97 0.00 0.00 0.00 0.00 1.38 0.00 24.14 3.45 8.97 145 14 0.16

0.00 0.00 8.00 9.33 0.00 0.00 0.00 0.00 2.67 0.00 12.00 0.00 13.33 75 14 0.10

4.38 0.00 4.38 6.57 0.73 0.00 0.00 0.00 0.00 0.73 28.47 0.00 6.57 137 14 0.15

2.16 2.88 7.19 6.47 0.00 0.72 0.00 0.00 5.04 0.00 27.34 0.00 12.95 139 16 0.13

1.52 0.00 6.06 4.55 0.00 1.52 0.00 0.00 0.00 0.00 45.45 0.00 4.55 66 16 0.24

0.00 0.00 12.41 4.83 0.00 0.00 0.00 0.00 0.00 0.00 48.97 0.00 16.55 145 10 0.29

6.71 0.00 0.67 1.34 0.00 0.00 0.00 0.00 0.67 0.00 36.24 0.00 13.42 149 18 0.19

0.00 0.00 7.14 2.38 0.00 0.79 1.59 0.00 1.59 0.00 23.02 0.00 7.14 126 16 0.13

0.00 0.00 0.00 5.71 0.00 0.00 0.00 0.00 0.00 0.00 37.14 0.00 11.43 35 9 0.21

0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 60.00 0.00 20.00 5 3 0.44

0.00 0.00 27.59 0.00 0.00 0.00 0.00 0.00 0.00 0.00 20.69 0.00 13.79 29 10 0.16

3.73 0.00 8.21 6.72 0.75 0.75 0.00 0.00 2.24 0.00 24.63 0.00 5.97 134 20 0.12

0.00 0.29 8.57 3.14 0.57 0.00 0.00 0.00 2.00 0.00 54.29 0.29 5.43 350 19 0.32

0.00 0.00 6.02 9.64 2.41 0.00 1.20 0.00 2.41 0.00 20.48 0.00 15.66 83 13 0.12

0.00 1.03 9.23 9.23 0.00 2.56 2.05 0.00 3.08 1.03 31.79 0.00 10.26 195 22 0.14

0.00 1.09 19.67 6.56 1.09 0.00 0.55 0.00 2.73 0.00 31.15 0.00 1.64 183 17 0.16

2). The cluster containing samples from the interval from 22-0 cm has high Pearsons Correlation

coefficient values for within-group similarity, and the largest between-group distances (see

Figure 2). This upper portion of the core is dominated by Brachiodontes sp., which comprises

greater than 50% of the molluscan assemblage in each sample from this section. Pinctada

radiata and Cerithium spp. are present in significant amounts (5%) in some samples from 22-0

cm.

Benthic Faunal Patterns

 Comparison of the benthic fauna present in core 19B with our modern data set, enables us to

interpret the salinity history for the Russell Banks site. The foraminiferal and molluscan records

from core 19B show distinct oscillations in salinity, with a gradual increase in salinity toward the

top of the core (Figure 3). In addition, a positive correlation (ρ =0.52) exists between increasing

Simpson diversity indices and decreasing salinity for the benthic foraminfera.

 The two dominant foraminiferal assemblages, Ammonia-Elphidium and miliolid, are very

similar to the Ammonia-Elphidium and Archaias-miliolid assemblages described from modern

Florida Bay sediments (Brewster-Wingard et al., 1996). The distribution of modern benthic

foraminifers in Florida Bay shows a strong association between the occurrence of A.

parkinsoniana and E. galvestonense mexicanum and typica with salinities less than 25 ppt

(Brewster-Wingard et al., 1996). Conversely, miliolids dominate where salinities are near normal

marine values (30 ppt). The intervals dominated by the miliolid assemblage (140 cm, 118-90 cm,

70-42 cm, and 18-0 cm) therefore indicate more stable and relatively higher average salinity (32-

35 ppt). These segments are interrupted by three periods of A-E assemblage dominance (140-118

cm, 90-70 cm, and 42-18 cm), indicating unstable and relatively low average salinity (<32 ppt).

 Molluscs are not as sensitive to variations in salinity as benthic foraminifers, consequently, the

molluscan data do not show the degree of fluctuation seen in the foraminiferal data (Figure 3).

The general trend of increasing percent abundance of euhaline and euhaline-polyhaline molluscs

upcore does follow the general trend of the foraminiferal plot, showing a gradual increase in

salinity upcore. No molluscan faunas restricted to terrestrial, fresh water, marsh, or upper

estuarine environments are present in core 19B, indicating this area has been relatively open bay

over the last century, and the salinity has probably not dropped below 12-15 ppt.

 Both the benthic foraminiferal assemblages and the molluscan assemblages show significant

changes between 70-66 cm and between 24-18 cm. These zones correspond to shifts from A-E

dominated assemblages to miliolid dominated assemblages, but the molluscs do not seem to

respond significantly to the decreases in salinity that mark the shift from miliolid assemblages

back to A-E assemblages. Almost all of the molluscs present in this core can be classified as

polyhaline and are tolerant of a wide range of salinities (from approximately 12 or 15 ppt to 30-

35 ppt), which could explain the patterns seen for the molluscs. If, however, the salinity had

dropped below ~15ppt during the periods of A-E dominance, then the molluscs would most

likely have shown a response. The areas of A-E dominance in the core represent salinities of 15-

25 ppt, with the lower number delineated by the absence of species of molluscs found in low

salinity waters of Florida Bay and the upper number constrained by the presence of low salinity

benthic foraminifera. The miliolid dominated zones represent salinities of 30 ppt or higher.
Foraminifers

Molluscs

Combined

1981

1962

1939
Hard Surface

Coarse Sediment or Sponges

Coarse Sediment

Coarse or Fine Sediment

Fine Sediment

Grass Beds or Sediment

Grass Beds or Coarse Sediment

90 100
 The suite of molluscs present in core 19B is more indicative of changes in substrate than

changes in salinity. Figure 4 illustrates the substrate patterns within the core, based on the

percent abundance of molluscs known to prefer those substrate types. The lowest portion of the

core, from 142-110 cm has significant numbers of both sediment dwellers and grass dwellers

present, with dominance of either group fluctuating. From 106-88 cm sediment dwellers

dominate, although grass dwellers are still present in significant numbers. The segment from 88-

22 cm is dominated by grass dwellers; above 68 cm the presence of species indicative of a

sediment substrate is negligible. The uppermost portion of the core, from 22 cm to the top, is

dominated by species that could live on either algae or grass.

 The shifts in abundance of molluscan substrate indicators at 88 cm, 68 cm, and 22 cm

correspond to changes seen in the benthic foraminiferal salinity indicators, but at this point the

significance of this relationship is not understood. However, since the benthic foraminifers used

for salinity indicators are not sensitive to changes in substrate, we believe the changing

foraminiferal patterns reflect changing salinity.

ANALYSIS AND DISCUSSION OF THE FLORA IN CORE 19A

Pollen

 The percent abundance data on pollen is presented in Table 3. Three pollen zones are

distinguishable based on both percent abundance and absolute pollen concentration (pollen

grains/gram dry sediment). The bottom zone (140-80 cm) is characterized by the highest

percentages of Pinus (pine) pollen (80-90%), and the lowest percentages of Quercus (oak)

(<6%), and pollen of the Chenopodiaceae/Amaranthaceae (pigweed family) and Asteraceae

(aster family) (Figure 5). No pollen of the Cyperaceae (sawgrass family) is present in this zone.

Total pollen concentration in this zone and the middle zone ranges from about 500-1,200

grains/gram, and the concentration of Quercus pollen is lower than the other zones, with <50

grains/gram (Figure 6).

 The middle zone (80-32 cm) is characterized by lower percentages of Pinus pollen (54-73%),

higher percentages of Quercus (6-10%), and higher concentrations of Quercus pollen (50-100

grains/gram). In both this and the upper zone, pollen of the Chenopodiaceae/Amaranthaceae and

Asteraceae are more abundant, comprising 3% and 2% of the assemblages, respectively. Pollen

of the Cyperaceae is present in low percentages in this and the upper zone.

 The upper zone has the highest pollen concentrations of the core, with most samples ranging

from 1,200-4,600 grains/gram. Several taxa contribute to these higher values, including Pinus,

Quercus, Myrica (wax myrtle), Chenopodiaceae/Amaranthaceae, and Asteraceae. Cephalanthus

(buttonbush) is present in low abundances (<1%) in this zone, and Liquidambar (sweet gum) is

absent from this zone.
Table 3

Russell Bank 19A

Percent Abundance of Pollen

Depth in core

AlnusApiaceaeAsteraceaeAvicenniaBetula BumeliaBursera simarubaCaryaCasuarinaCeltisCephalanthusChenopodiaceae/ AmaranthaceaeConocarpusCyperaceaeDecodonEricaceaeEuphorbiaceaeFabaceaeFraxinusIlexJuglans

0-1 cm 0.00 0.00 2.55 0.00 0.00 0.00 0.00 0.00 4.82 0.00 0.28 4.25 0.00 0.00 0.00 0.00 0.00 1.42 0.00 0.00 0.00

 4-5 cm 0.57 0.00 2.01 0.00 0.00 0.00 0.00 0.29 1.15 0.00 0.29 2.87 0.29 1.15 0.00 0.00 0.29 0.57 0.00 0.29 0.29

 8-9 cm 0.32 0.00 3.22 0.00 0.00 0.00 0.00 0.00 1.29 0.00 0.32 0.96 0.00 0.64 0.00 0.00 0.00 0.32 0.00 0.00 0.00

20-21 cm 0.00 0.00 4.09 0.31 0.00 0.00 0.00 0.00 3.14 0.00 0.63 5.97 0.00 0.00 0.00 0.00 0.00 2.20 0.00 0.00 0.00

32-34 cm 0.30 0.00 3.32 0.00 0.30 0.30 0.00 0.00 2.11 0.00 0.00 3.32 0.30 0.30 0.00 0.00 0.00 1.21 0.00 0.30 0.30

44-46 cm 0.80 0.00 7.77 0.00 0.00 0.00 0.00 0.27 2.14 0.00 0.00 4.29 0.00 0.80 0.00 0.00 0.27 1.07 0.00 0.54 0.00

56-58 cm 0.31 0.00 4.39 0.00 0.00 0.00 0.00 0.31 1.57 0.00 0.00 6.90 0.00 0.63 0.00 0.63 0.00 0.94 0.31 0.00 0.00

68-70 cm 1.68 0.00 2.51 0.00 0.28 0.00 0.28 0.84 0.56 0.00 0.00 3.07 0.00 0.56 0.00 0.00 0.00 0.84 0.00 0.00 0.00

80-82 cm 0.00 0.00 2.38 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 4.76 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00

92-94 cm 0.54 0.00 0.54 0.00 0.00 0.27 0.00 0.82 0.27 0.00 0.00 0.54 0.00 0.00 0.00 0.00 0.00 0.82 0.27 0.00 0.00

104-106 cm 0.00 0.29 1.15 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 2.30 0.00 0.00 0.57 0.00 0.00 1.15 0.00 0.00 0.00

116-118 cm 0.62 0.00 0.62 0.00 0.00 0.00 0.00 0.00 0.00 0.31 0.00 1.85 0.31 0.00 0.00 0.00 0.00 0.62 0.00 0.00 0.00

128-130 cm 0.00 0.00 0.61 0.00 0.00 0.00 0.00 0.30 0.00 0.00 0.00 0.91 0.00 0.00 0.00 0.30 0.00 0.61 0.00 0.00 0.00

136-138 cm 0.60 0.00 0.60 0.30 0.00 0.30 0.60 1.81 0.00 0.00 0.00 0.91 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00

138-140 cm 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.81 0.00 0.00 0.00 2.44 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00
Table 3

Russell Bank 19A

Percent Abundance of Pollen

Depth in core

0-1 cm 

 4-5 cm 

 8-9 cm 

20-21 cm 

32-34 cm 

44-46 cm 

56-58 cm 

68-70 cm 

80-82 cm 

92-94 cm 

104-106 cm 

116-118 cm 

128-130 cm 

136-138 cm 

138-140 cm 

LiquidambarMagnoliaMyricaNyssaOstrya/ CarpinusPinusPlaneraPoaceaeQuercusRhizophoraRutaceaeSagittariaSalix

Taxodiaceae/ Cupressaceae/ Taxaceae

TyphaUlmusTotal Pollen Counted

0.00 0.00 2.83 0.00 0.28 68.56 0.00 0.28 10.76 0.28 0.00 0.28 0.00 0.00 0.00 0.57 353

0.00 0.00 0.86 0.00 0.00 69.05 0.00 0.29 13.75 0.29 0.00 0.29 0.00 0.00 0.00 0.00 349

0.00 0.00 2.25 0.00 0.00 73.95 0.00 0.32 9.32 0.96 0.32 0.32 0.32 0.00 0.96 0.32 321

0.00 0.00 10.69 0.00 0.63 56.60 0.00 0.31 11.01 0.00 0.00 0.00 0.00 0.00 0.31 0.00 321

0.30 0.00 8.46 0.00 0.00 67.37 0.00 0.30 6.34 0.00 0.00 0.00 0.30 0.30 0.30 0.00 332

1.07 0.00 4.29 0.27 0.00 54.16 0.00 1.07 10.46 0.27 0.00 0.00 0.27 0.27 0.54 0.54 378

0.00 0.31 3.76 0.00 0.00 63.95 0.00 0.31 6.90 0.94 0.00 0.31 0.31 0.31 0.63 0.31 320

0.28 0.28 4.47 0.00 0.00 73.46 0.00 0.00 6.15 0.28 0.00 0.00 0.28 0.00 1.12 0.28 358

1.19 0.00 3.57 0.00 0.00 79.76 0.00 0.00 5.95 0.00 0.00 0.00 0.00 0.00 0.00 0.00 85

0.82 0.00 4.08 0.00 0.00 86.96 0.00 0.00 2.45 0.27 0.00 0.00 0.00 0.27 0.00 0.00 371

0.29 0.00 7.47 0.00 0.00 80.17 0.00 0.29 3.16 0.57 0.00 0.00 0.00 0.29 0.29 0.00 350

0.00 0.00 3.38 0.00 0.00 89.23 0.00 0.31 1.23 0.31 0.00 0.00 0.31 0.00 0.31 0.00 326

0.30 0.00 3.96 0.00 0.00 86.28 0.00 0.30 4.57 0.00 0.00 0.00 0.30 0.00 0.00 0.00 331

0.30 0.00 2.42 0.00 0.00 87.92 0.30 0.00 1.81 0.00 0.00 0.00 0.00 0.00 0.30 0.00 332

0.81 0.00 1.63 0.00 0.00 88.62 0.00 0.00 5.69 0.00 0.00 0.00 0.00 0.00 0.00 0.00 123
ca

CephalanthusChenopodiaceae/

 Amaranthaceae

PoaceaeCyperaceaeAsteraceae

10

20

30

40

50

60

e)

(Wax Myrtle)

(Button Bush)

(Pig Weed)

(Grass Family)

(Sawgrass Family)

(Aster Family)
0 50 100 150 200 250 300 350 400

Quercus

0 50

Casuarina

0 50 100 150 200 250 300

Myrica

0 50 100 150

Chenopods

0

Cyperaceae

0 50 100

Asteraceae 

10

20

30

40

50

60

70

80

90

100

110

120

130

Depth

cm Pinus

0 1000 2000 3000

Total Pollen Concentration

10

20

30

40

50

60

70

80

90

100

110

120

130

0 1000 2000 3000 4000

Figure 6: Total concentration of pollen (grains/gram) for core Russell Bank 19A (note different scales).
Dinocysts

 Dinocyst recovery in all samples was low. Most microscope slides are heavily dominated by

organic debris and the maximum number of specimens observed in any sample was 214.

Absolute abundance ranges from 77.9 to 473.6 cysts/gram. These values are one to two orders of

magnitude below those reported by Wall et al. (1977) for samples from the Middle Atlantic

Bight and western South Africa and are consistent with high sedimentation rates. These absolute

abundances in the sediments are far below bloom concentrations, in which the number of living

cells per ml of water may exceed 50 million.

 The dinocyst assemblages in the Russell Bank 19A core consist of less than 10 taxa (Table 4).

Various species of the genus Spiniferites Mantell dominate all samples (61 to 79 percent). Due to

poor preservation and taxonomic difficulties the individual species of this genus were not

differentiated; S. mirabilis (Rossignol) Sarjeant, S. ramosus (Ehrenberg) Mantell, S. scabratus

(Wall) Sarjeant, and other forms are present. Operculodinium Wall spp. (O. israelianum

(Rossignol) Wall or Operculodinium species undifferentiated) are present in all samples in

amounts of 5 to 19 percent. Polysphaeridium zoharyi (Rossignol) Bujak et al. is present in all

samples and comprises up to 16 percent of the assemblages. Most samples included low numbers

of Lingulodinium machaerophorum (Deflandre & Cookson) Wall, Nematosphaeropsis rigida

Wrenn, and (or) Tectatodinium pellitum Wall. Only two samples contained a single specimen

each of the family Congruentidiaceae.

 Most samples from Russell Bank core 19A are quite similar to one another (Figure 7).

Throughout the core, the dinocyst Polysphaeridium zoharyi ranges in abundance from 0-16

percent, which is considerably lower than in the Bob Allen 6A (Wingard et al., 1995) and Little

Madeira Bay T24 (Ishman et al., 1996) cores. With one exception (80-82 cm), increased absolute

abundance of Spiniferites spp. is accompanied by increased absolute abundance of P. zoharyi

(Figure 8). This relationship suggests that absolute abundances in this core are a function of

sediment supply rather than cyst production. The sample at 80-82 cm is anomalous: the high

absolute abundance of cysts is attributable to Spiniferites spp. and fewer than 30 total cysts were

found on each slide. This sample may represent a case of an increase in Spiniferites cyst

production and an increase in the amount of organic debris in proportion to sediment supply. The

lowest samples (132-134 cm and 136-138 cm) show both low absolute abundances of all cyst

types and low percentages of P. zoharyi.

Floral Patterns

 Changes occur in the pollen and dinocyst assemblages in core 19A, but the significance of

these changes is unclear. Three zones are distinguishable for the pollen, but the differences

among them are very subtle, and any interpretation of patterns of vegetational change would be

premature. However, it is apparent that the vegetation changed in response to some

environmental factor at those times; correlation with on-shore cores would be necessary to

establish the nature of the changes. Dinocyst abundance fluctuates in the core, with two peaks at

118-104 cm and 82-80 cm, but the assemblages are relatively stable throughout the core.
Table 4. Dinocyst data from Russell Bank 19A Polysphaeridium zoharyi Spiniferites spp. Operculodinium spp. Nematosphaeropsis rigida Lingulodinium machaerophorum Tectatodinium pellitum

Tuberculodinium vancampoaeCongruentidiaceaeOtherTOTAL DINOCYSTS COUNTED

Depth 

(cm)

Wt 

(g) Cysts/g

Slides 

examined

0-1 7.4 77.9 2 12.9 74.2 9.7 0.0 3.2 0.0 0.0 0.0 0.0 31

20-21 11.5 136.3 1 12.3 63.0 7.4 4.9 4.9 6.2 0.0 1.2 0.0 81

44-46 36.3 92.1 1 2.4 75.0 9.5 3.6 4.8 1.2 0.0 0.0 3.6 84

68-70 35.8 145.4 1 11.4 70.5 9.5 1.0 3.8 2.9 0.0 1.0 0.0 105

80-82 33.7 373.2 2 1.9 81.1 13.2 0.0 3.8 0.0 0.0 0.0 0.0 53

92-94 38.5 204.9 1 8.4 72.0 11.9 4.9 2.8 0.0 0.0 0.0 0.0 143

104-106 33.1 473.6 1 12.8 63.6 13.3 7.7 1.0 0.5 0.0 0.0 1.0 195

116-118 35.0 345.1 1 14.1 67.6 10.6 0.7 6.3 0.7 0.0 0.0 0.0 142

128-130 39.0 185.4 1 12.1 61.2 17.8 5.1 2.8 0.5 0.5 0.0 0.0 214

132-134 32.1 128.8 1 3.4 75.4 12.7 6.8 1.7 0.0 0.0 0.0 0.0 118

136-138 37.1 202.8 1 6.6 74.7 11.0 5.5 1.1 1.1 0.0 0.0 0.0 91

Species

Percent abundance
Comparison of these data to additional terrestrial and marine cores may lead to a better

understanding of the patterns seen here.

210PB AGE MODEL FOR THE RUSSELL BANKS SITE

 The activity of 210Pb (dpm/gram) is shown for 19B and 19C in Figures 9 and 10. The

sedimentation rate for the Russell Bank site is based on the results from 19C, because both 210Pb

and Ra analyses have been completed for that core; the rate equals 1.22 cm/year +/- 0.05.

The 210Pb curves for cores 19B and 19C are almost identical, therefore we make the assumption

that the rate of sediment accumulation is the same in the two cores. No 210Pb analyses have been

done for core 19A to date.

SUMMARY

 The fauna and flora present in the Russell Bank cores 19A and 19B record an approximately

120-year history of fluctuating environmental changes. The benthic foraminifera document

periods of fluctuating salinity, with a gradual increase in salinity upcore. The molluscan data are

consistent with the foraminiferal data, showing increasing salinity upcore, but without the degree

of fluctuation indicated by the benthic foraminifera. The benthic fauna show significant changes

in the assemblages at 70-66 cm and 24-18 cm, which correspond to approximately 1937-1940

and 1975-1980. A similar shift occurred at 118 cm (approximately 1898), which is not as clearly

seen in the molluscan faunal data. These periods represent shifts from low salinity (12-15 ppt) to

higher average salinity (30 ppt). In addition, the benthic foraminiferal assemblages shift from

periods of higher average salinity, to periods of lower salinity at 140 cm, 90 cm, and 42 cm,

which correspond to approximately 1880, 1921, and 1960 respectively.

 The molluscan fauna indicate changes occurring in the substrate at the Russell Banks site.

Sediment and grass (probably Thalassia) apparently were equally available for habitation from

142-110 cm, or approximately 1878-1904. Although grass was still available, bare-sediment

dominated the area from 106-88 cm, or approximately 1908-1922. From 88-22 cm, or

approximately 1922-1976, grass was the dominant substrate, and from approximately 1939 (68

cm) to the present, the presence of bare-sediment bottoms was negligible at the site.

Significantly, from 22 cm, or approximately 1976 to the present, the molluscan fauna is

dominated by species that can live equally well on algae or seagrass.

 The pollen present in core 19A show three periods of subtle shifts in the onshore vegetation in

response to some environmental factor. These changes occur at 80 cm and at 32 cm, or

approximately 1929 and 1968. If we assume that core 19A and 19B have similar sedimentation

rates, then the shifts in the onshore vegetation indicated by the pollen seen in 19A occur

approximately 7-8 years prior to changes in Florida Bay as indicated by the benthic fauna in

19B. However, until we see this pattern repeated in the same core or until a 210Pb analysis is
0 20 40 60 80 100

0-1

20-21

44-46

68-70

80-82

92-94

104-106

116-118

128-130

132-134

136-138

Operculodinium spp.

Nematosphaeropsis rigida

Lingulodinium machaerophorum

Spiniferites spp.

Polysphaeridium zoharyi

All others

Percent Cysts/gram 

0 100 200 300 400 500

Figure 7. Percent and absolute abundances of dinocysts for core 19A.

Depth (cm)
00 300 400

tes

gram

aeridium zoharyi


completed for core 19A, we can not be certain of its significance because our assumption of

similar sedimentation rates for cores 19A and 19B may not be correct.

 Two peaks in dinocyst abundance (cysts/gram) occur in the samples examined: 118-104 cm

(approximately 1898-1909) and 82-80 cm (approximately 1927-1929). These occur during a

period of near normal marine (30 ppt) and stable salinity, as indicated by the benthic

foraminifera. These periods may represent increased dinocyst production and decreased sediment

supply, but the composition of the dinocyst assemblages remains relatively stable throughout the

core.

 The pattern of increased salinity upcore, documented here for Russell Banks 19B, is consistent

with patterns seen in core T24 from the mouth of Taylor Creek in Little Madeira Bay (Ishman et

al., 1996), and in core 6A from Bob Allen mudbank (Wingard et al., 1995). The correspondence

between changes in salinity and onshore changes in vegetation is also consistent with results

from the previous cores. These patterns will continue to be investigated at additional sites in

Florida Bay and the terrestrial Everglades in order to establish the sequence and timing of events

throughout the ecosystem, and to determine linkages between the marine and terrestrial systems.
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