Foraminifera and Climate
Sindia Sosdian
Rutgers University
What is the job of an
oceanographer?
Biology Geology
Climate
Chemistry
Physics
What are Pale-oceanographers?
We study the history of the
oceans in the geologic past
+ = with regard to climate
change!
Changes in the ocean can affect climate!
What is climate?
• Climate is the average and variations of
weather over long periods of time.
What is a good indicator of climate?
Before the
temperature instrumental
record, how does
one measure
temperature?
Motivation
FORAMinifera …
the size of a grain of sand or smaller
Amoebas are….
• protozoa that moves by means of temporary projections called
psuedopods, and is well-known as a representative unicellular
organism.
• They have a shell like a clam that protects their body and helps them
survive.
1-Food time
(2:13)
2-Floating
around (3:15)
3-Hungry
again. (8:49)
In the ocean…
Forams live in the surface or deep. When they
die their shell rains down or is deposited into the
sediment.
Surface ocean
Deep ocean
Mud/Sediment
Planktonics-Forams that live in the surface ocean
(popcorn, inflated)
Benthics -Forams that live in the deep ocean
Benthic foraminifera
Some like to live in Some like to live on
the dirt like worms top of the dirt like
grasshoppers
“epifauna”
“infauna”
You can tell where they live by their body shape!
See 3-D example!
Difference in shell shape
Epifauna water
Abundance of epifauna/infauna
-Food supply
Infauna -Oxygen levels
-Current activity
Epifauna Oxygen and
sediment labile food
Low-oxygen
Infauna
tolerant and
refractory food
Example (1)-Benthic foraminifera abundance
Species abundance
epifauna
infauna
- +
Food
+ -
Oxygen
Shell (Test) Shape
• Shells are built of hollow chambers separated by partitions with
small opening that connects the chambers
• the shell may be made of organic compounds, sand grains and
other particles cemented together, or crystalline calcite (CaCO3)
Let’s try drawing and shaping
a test!!
Planktonics-float in the sea
O. universa
Classification
• Based on characters of shell shape unilocular -- a single chamber
– Wall composition and structure
– chamber shape and arrangement
– the shape and position of any apertures
– surface ornamentation
uniserial -- chambers added in a single
– other morphologic features of the shell linear series
biserial -- chambers added in a double linear series
tubular -- a simple hollow tube.
trochospiral -- chambers added in a
coil that forms a spire like a snail shell. planispiral -- chambers added in
a coil within a single plane.
Example (2) Classification of foraminifera
Word Bank
unilocular
uniserial
tubular
biserial
planispiral
trochospiral
Playing with mud
(shell collection)
modern
1000
years
ago!!
Let’s wash some mud
and find some forams
Take a look under the microscope
a b c d
infaunal epifaunal planktonic planktonic
benthic benthic
Geological slide
Just like trees…
some like
warm
weather It is cold down
here!
some like
cold
weather
Foraminifera and climate
• (1) Species abundance
• (2) Geochemical tracers in their shell
+
Planktonic Species
**abundance for each planktonic
Abundance foraminifera varies depending on
temperature
Gulf stream waters
Warm central Atlantic
From WHOI-Oceanus
Example (3)- Polar bear of Planktonic Foraminifera
• N. pachyderma
-left coiling (<8ºC) -right coiling (> 8ºC)
N. Pachy (left)/ N. Pachy (right)
100 1
% N. Pachyderma (left)
0 0
0 10 20 30 0 10 20 30
Sea surface temperature (ºC) Sea surface temperature (ºC)
Geochemical tracers
Substitution of Mg (for Ca) in calcium carbonate shells Ca2+
Mg
CaCO3 + Mg+2 -> MgCO3 + Ca+2
C
Mg/Ca=0.38exp(0.09x T)
Mg/Ca=0.867exp(0.11x T)
Benthic foraminifera Planktonic foraminifera
Mg/Ca ratio in calcite shells is a function of temperature!!
Example (4)- Temperature change during the last ice age
How cold was it for these sub-zero heroes during the
ice age?
Mg/Ca
Modern Ice age (20,000 years ago)
T (ºC) T (ºC) ice
Mg/Ca modern Mg/Ca ice age modern age Δ T (ºC)
Planktonic 2.5 1.9 20.5 17.5 3
Benthic 1.2 0.8 3 1 2
Geochemical tracers
Incorporation of Mg in calcium carbonate (calcite/aragonite) shells
CaCO3 + Mg+2 -> MgCO3 + Ca+2
Mg/Ca=0.38exp(0.09x T)
Mg/Ca=0.867exp(0.11x T)
Benthic foraminifera Planktonic foraminifera
Ocean acidification and foraminifera
The phenomenon is the result of
simple chemistry.
• Carbon dioxide dissolves in
seawater to form weak,
carbonic acid.
• The problem is, acids dissolve
limestone, or calcium
carbonate, which is the main
constituent of seashells.
• As the oceans become more
acidic, it will become
increasingly difficult for
creatures' shells to form.
Shell morphology and thickness
Plankton
pCO2
Go to the video!!
4:35 to 8:10
http://www.abc.net.au/catalyst/stories/s2029
333.htm
Thank you !!!
