U. Kienel,
B. Brademann, N. Dräger, P. Dulski, F. Ott, B. Plessen, A. Brauer
Linking diatom deposition
with the spring temperature gradient
Lake Tiefer See (NE Germany)
Phacotus
Formation of varves and seasonal layers
Sedimen t depth [cm]
Ca [cps]
0 4000
? When, how much and which material
? Which conditions (Weather / Limnology)
? Signal transfer
50µm
20µm
Annual layer = Varve
Diatoms Siliceous algae Calcite Detritus
Si Ca
Si [cps] 100
Ti, K
Cyanobacteria
Subsample Material
Sequential trap 2‐Cylinder trap 4‐Cylinder trap (12 m + 5 m)
Monitoring station Weather staion Water probe T‐logger chain
Measure conditions
Lake Tiefer See Monitoring – Instrumentation
Lake Tiefer See Monitoring – Instrumentation
Water depth [m]
Matter formation + deposition Weather / Lake conditions
30 d 2 h
10 min.
183 d 15 d
30 days
T P Wind PAR Chemistry T logger Production Deposition
Increment Interval
Sequential Trap
2- cylinder
Trap 4-cylinder
Traps
Water probe
12 h T pH EC Turb. Chla
DO redox
Trapped hypolimnion deposition
0 1000 2000 3000 4000 5000 6000 7000
0 92 183 275 366 458 549 641 732
S. neoastrea + parvus C. comensis
A. formosa F. crotonensis Fragilaria chains A. islandica
A. islandica Fragilaria F. crotonensis A. formosa
Deposition [g m
‐2d
‐1]
no datano data
6.4
0.0 1.0 2.0 3.0 4.0 5.0
0 92 183 275 366 458 549 641 732
Day since 01.01.2012
Deposition [g m-2 d-1 ]
Organic matter CaCO
3non‐CaCO
3IM
2012 2013
C. comensis Stephanodiscus
10
6Diatoms [g m
‐2d
‐1]
Siliceous algae
IM deposition transferred to Diatom Si
0 1 2 3
0 92 183 275 366 458 549 641 732
0 1 2 3
0 92 183 275 366 458 549 641 732
Non‐CaCO
3IM Deposition [g m
‐2d
‐1]
Silica
Deposition [g m
‐2d
‐1]
Stephanodiscus
log10[silica content] = 1.03 log10[biovolume] ‐2.45 (Conley et al. 1989)
Si 10‐12 g per cell S. neoastrea 1545
S. parvus 371 C. comensis 103
No diatoms Low detritus
no datano data
2012 2013
0
20
40
60
0 92 183 275 366 458 549 641 732
Weather and Lake conditions –> Lake mixing
0
400
800
1200
0 92 183 275 366 458 549 641 732
-20 -10 0 10 20 30
0 92 183 275 366 458 549 641 732
Wind
fetch length [m]
Air temperature [°C]
Water
temperature [°C]
2012 2013
Ice cover Water
depth
[m]
Lake mixing depth related to T water and wind
Wedderburn number W = 1
depth to which water column is mixed by wind (Walsby & Schanz 2002)
W = (g h
2) / (
wU*
2L)
water density difference surface and depth h g gravitational acceleration
wwater density L wind fetch length
U* wind‐induced shear velocity (Spigel & Imberger 1987)
U*
2= (
a/
w) C
dU
w2
a/
wdensity ratio air / water (0.0012) C
ddrag coefficient (0.0013)
U
wwind speed
Buoyancy Wind action
L
Diatoms and Spring mixing ‐ transfer function
0 20 40
60
0 92 183 275 366 458 549 641 732
0 1 2 3
-20 -10 0 10 20 30
0 92 183 275 366 458 549 641 732
Mixing depth [m]
T
Air[°C]
Diatom Si
deposition [g m
‐2d
‐1] 2012 2013
0 °C 5 °C
T Duration 0 ‐ > 5 ° C
[days]
Sediment Si mean yr
‐1Schwerin TDur since 1890
no data
Transfer : Diatom Si = 1/Tduration 0 ‐ ≥ 5 ° C
0 20 40 60 80 100 120
0 20 40 60 80 100
Spring warming
0 – 5°C [days]
y = ‐1.01x + 105.33 R² = 0.31
Diatom Si
[count average yr‐1]
r = 0.56 N = 86 p < 0.0001
0 20 40 60 80 100 120 140 160 180
1920 1930 1940 1950 1960 1970 1980 1990 2000 2010 0 20 40 60 80 100
Calculated from FLake
(Mironow 2008)
Transfer : Diatom Si = 1/Spring warming
Spring warming
0 – 5°C [days]
Bucket elevator 1984‐1995 Lifestock
farming since 1975
0 20 40 60 80 100 120
0 20 40 60 80 100
y = ‐1.21x + 109.96 R² = 0.41
Diatom Si
[count average yr‐1]
Testing the stability of the Diatom – T relation
BLZ Diatom Si * 10
‐1count average yr‐1
Spring warming
0 – 5°C [days]
Si avg count yr-1 TSK vs. BLZ*10-1
y = 0.53x + 27.98 R2 = 0.33 0
20 40 60 80 100
0 20 40 60 80 100
y = -1.25x + 114.03 R2 = 0.22
0 20 40 60 80 100 120
0 20 40 60 80 100
y = ‐1.25x + 114.03 R² = 0.22
Breiter Luzin
*10
‐1Tiefer See
TSK
-20 0 20 40 60 80 100 120
1945 1955 1965 1975 1985 1995 2005 2015
0 20 40 60 80 100
y = 0.53x + 27.98
R² = 0.33
First‐step conclusions
Questions
TDuration 0 to ≥ 5°C 1/Diatom Si deposition
Process: Mixing depth ‐> Nutrients Light availablity Systematic?: Breiter Luzin
Chance: Nutrient threshold Problem: Detrital Si
Are the relations systematic?
Anthropogenic thresholds for climate signal transfer?
Stationarity of proxies?
What are the system response times?
~
Outlook: Carbonate 18 O preserves July temperature?
y = -0.16x - 1.69 R2 = 0.56
-6 -5 -4 -3
14 19 24
14 16 18 20 22 24
1975 1980 1985 1990 1995 2000 2005 2010 2015
-6
-5
-4
-3
Tair JUL [°C]
d18Ocarb ‰ BLZ
-0.04 0.00 0.04 0.08 0.12
1975 1980 1985 1990 1995 2000 2005 2010 2015
0 3 6 9
TP [mg/l] 5m CaCO3 [mg/l] 5m
18O
carb[%
oPDB]
T
Air[°C]
July T
Air[°C]
0 1 2 3
0 0 0 0 0 0 0 1 1 1 1 1 1J F M A M J J A S O N D
Month TP [mgL
‐1] 5m
1993 – 2012 y = ‐0.16x ‐0.69 R
2= 0.56
CaCO
3[mgL
‐1] 5m
Threshold: eutrophic
0 40 80 120 160
0 50 100 150 200 250 300 350 400 450 500 550 600 650 700
Spring warming 0 –> 5°C [days]
100 days 20 days
Si
[cps]
Varved
Potential for T ‐ transfer in TSK long core
Detrital Si
Age [yr BP]
Site map: Lakes and their varved sediments
Alt Gaarz
63 m / 65 m a.s.l.
Sophienhof Blücherhof
93.8 m a.s.l.
93.3 m a.s.l.
1 km
Lakes Tiefer See (TSK) Varved sediments [yr AD] since 1924
Lake volume [106m3] 14
Lake area [km²] 0.76
Lake depth max [m] 63
El. Conduct. [µS cm‐1] 520 / 560
TP [µg L‐1] 47 (0)
TN [mg L‐1] 1.3
Trophic state / reference Mesotr. / Oligotr.