Common aquatic proxies

1
Common aquatic proxies
Structural material
Group
diatoms chrysophytes sponges radiolaria foraminife
ra ostracodes
Silicates Carbonates
agglutinated forams have clastic, not carbonate
tests
2
Diatoms
Unicellular, eukaryotic, generally photosynthetic
microorganisms encased in a cell wall impregnated
with silica. They tolerate a wide range of
thermal, pH and salinity conditions in aquatic
habitats and wetland soils.
photo Yuki Sawai
3
Centric and pennate diatoms
2
2
1
3
2
1
1. Valve face 2. Mantle 3. Girdle (bands
cingula)
3
4
Diatoms(major groups based on cell morphology
and ornamentation)
Eucentric - circular valve outline radially
symmetrical valve ornamentation. Eccentric -
bipolar or multipolar outline radial
symmetry. Araphid - bilateral symmetry to a
central thickening (sternum). Monoraphid -
bilateral symmetry sternum has fissure (raphe)
on onevalve only. Naviculoid - bilateral
symmetry sternum has raphe on both
valves. Cymbelloid - raphes on both valves
assymetric on either the longitudinal or
transverse axis. Nitzschoid - raphes on both
valves raised above valve on keel. Surirelloid -
raphes on both valves raised above valve on
wing. Epithemoid - raphes on both valves within a
canal.
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Eucentric diatoms
Thalassiosira
Aulacoseira lacustris
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Araphid (e.g. Fragilaria)and monoraphid
diatoms(e.g. Cocconeis)
Epivalve (with raphe) Hypovalve ( no
raphe)
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Naviculoid diatomsPinnularia abaujensis
Diploneis finnica
Frustulia rhomboides
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Cymbelloid diatoms
Cymbella affinis
Eunotioid diatoms
Eunotia formica
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Nitschzoid diatoms
Epithemoid diatoms
canal
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Surirelloid diatoms
www.marbot.gu.se/files/melissa/checklist/diatoms.h
tmllist
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Diatoms taxonomic problems(e.g. freshwater and
brackish Fragilariaceae)
Round, Crawford Mann (1990)
Krammer Lange-Bertalot (1991)
Asterionella Centronella Ceratoneis Diatoma Hannea
Meridion
Fragilaria Fragilariforma Pseudostaurosira Punctas
triata Staurosira Staurosirella Opephora(marine)
Martyana Ctenophora Neosynedra Synedra Tabularia
Asterionella Centronella Ceratoneis Diatoma Fragil
aria Meridion Opephora Synedra Tetracyclus Tabella
ria
Tabellariaceae
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Fragilariamorphology
Image in light microscope
a
b
c
SEM images a) Fragilariforma b) Staurosirella c)
Punctastriata d) Staurosira e) Pseudostaurosira
d
e
From Round et al. (1990) The Diatoms. Cambridge
U.P.
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Diatoms taxonomic problems - synonymies
In Great Lakes catalogue (www.umich.edu/phytolab
/Great lakes/DiatomHomePage) as Oestrupia
zachariasi
In California Academy of Sciences catalogue
(www.calacademy.org/research/diatoms)as
Oestrupia bicontracta
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Examples of applications of diatoms in
palaeoenvironmental studies
Sea-level changewestern Scotland Palaeoseismolo
gyDiscovery Bay, WA Palaeolimnologydepth
Lake Oloiden, Kenya pH Baby Lake,
Ontario temperature Längsee, Austria
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Diatom record of sea-level change in an
isolation basin on the west coast of Scotland
16
DiscoveryBay, WADiatom record of
tsunamiinundation of marshes
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Lake Oloiden, Kenya
(salt-tolerant benthic, naviculoid)
(planktonic centric)
18
Diatom-inferred pH change, Baby Lake, Ontario
(1870-1990)
pH
5 6 7
from Dixit et al. (1992) Water , Air and Soil
Pollution, 62, 75-87.
19
Late-Glacial summer surface water temperature,
Längsee (548 m asl), Austria
Pollen Diatoms Surface
Water Temp
from Schmidt et al. (1998) Aquatic Sciences, 60,
56-88.
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Chrysophytes
Although it is difficult to distinguish species
in LM, the resting spores of Chrysophytes may
prove useful as supplementary sources of
environmental information in freshwater habitats.
Chrysophyte stomatocyst (resting spore)
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Freshwater sponges (e.g. Heteromyenia sp.?)
1. sponge spicules and diatoms (Stump Lake,
BC) 2. gemmosclere 3. mega and microscleres
1
3
2
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Sponge palaeofaunas, 20 ka BP - PD (Jackson
Pond, KY)

H. latitientia now restricted to northern New
England
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Radiolarians
Rhizoplegma borealia

• marine unicellular protists
• siliceous skeletons in soft cytoplasm lipid
  globules in cytoplasm (and spines?) enhance
  buoyancy
• planktonic occur from surface to depths of
  several hundred meters
• size range 2 - 30 mm diameter
• families distinguished by skeletal shapes some
  groups are solitary, others colonial
• species abundance related to water temp.,
  salinity, and nutrient status.

Lophospyris pentagona
Lamprocyclas maritalis
source www. radiolaria.org
24
An example of the application of radiolarians in
palaeo-oceanographic studies
Core 1019
from Pisias et al (2001) Quat. Sci Rev., 20,
1561-1576
25
Radiolarian assemblages in the Pacific Ocean
from Pisias et al.(2001) Quat. Sci Rev., 20,
1561-1576.
Max. factor loadings
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Radiolarian assemblages in core 1019 (989 m water
depth)
YD
T1
green line GISP2 d18O record black
lineradiolarian record
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Foraminifera
Foraminifera are single-celled protists that live
in all marine environments. They inhabit the sea
floor (benthonic forms) or the surface layer of
the oceans (planktonic forms). Most of the soft
tissue of the cell of a foraminifer is enclosed
within a test which may be composed of secreted
organic compounds and mineral grains cemented
together (agglutinated test), or secreted calcite
or aragonite (calcareous test). The calcareous
tests are divided, in part, into hyaline and
porcellaneous types based on the orientation of
the calcium carbonate crystallites comprising the
test.
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Examples of (1) agglutinated and (2) calcareous
foraminifers
(1) Textularia forquata
(2) Elphidium excavatum
length 0.18 mm breadth 0.09 mm
max. diam. 0.48 mm thickness 0.20 mm
foram photos and info. from http//www.cs.uwindsor
.ca/meta-index/fossils/woop.html
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Examples of applications of foraminifera in
palaeoenvironmental studies coiling and ocean
temperature
N. pachy left
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Forams aplanktic episodes in the Red Sea
confirm eustatic lowstands
from Rohling et al. (1998) Nature, 394, 162-165.
Low RSL hypersaline Red Sea no planktonic
forams
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Palaeo-temperature, core DSDP-609(N. Atlantic)
based on N. pachy left
100
0
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Ostracodes
Bensonocythere americana
Ostracodes are crustaceans with two calcareous
valves hinged along the dorsal margin to form a
carapace which is commonly ovate or
kidney-shaped. They have adapted to marine
environments oceans, estuaries and lagoons
hypersaline environments freshwater environments
lakes, ponds, rivers and springs and
terrestrial environments such as the moist humus
of forests. The majority of ostracodes are
benthonic in habit.
dorsal view
lateral view
source www.cs.uwindsor.ca/meta-index/fossils/woop
.html
length 0.69 mm height 0.38 mm   width 0.35
mm
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Applications of ostracodes in Quaternary
palaeoenvironmental research Lake Manitoba
during the Holocene
Salinity (g/L)
1 2 3 4
from Curry (1997) Can. J. Earth Sci., 34,
699-708.
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Applications of ostracodeschanges in depth
ranges (controlled by water temperature)record
oceanographicconditions on Bahama Bank
pores
4 cooler
Krithe sp.
2 cooler
from Rodriguez-Lazaro Cronin (1999)
Palaeo3, 152, 339-364.
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Aquatic proxies as sources of proxy
dataadvantages

• short generation times quick response to
  environmental change
• many groups cosmopolitan (cf. regional floras and
  megafaunas)
• in situ, not derived from surrounding terrestrial
  habitats, therefore representative of conditions
  within the water body, rather than the watershed.

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Aquatic proxies as sources of proxy
datalimitations

• no parent for reference material (cf. pollen
  spores)
• species concept often difficult to apply
• small forms hard to distinguish in LM
• unstable taxonomies many synonyms
• meagre ecological information
• often responsive to a wide variety of
  inter-linked environmental stimuli (water
  temperature, conductivity, pH, nutrient status,
  depth)
• small size leads to homogenization by currents,
  etc. (i.e. allochthonous components common in
  fossil assemblages).