a buffet the size of the ocean! the heterotroph group: alison dominy, sean lu, ellen winant
TRANSCRIPT
A buffet the size of the ocean!
The heterotroph group:
Alison Dominy,
Sean Lu,
Ellen Winant
GOALS
A. Compare animal abundance within the benthos and water column.
B. Investigate heterotrophic processes that
influence rates of exchange of matter and energy between the water column and the benthos.
Zooplankton Feeding Experiment
Unusually high rates of ingestion and volume swept clear (VSC).
Data points from E. pileatus feeding experiment comparing volume swept clear per copepod per hour in relation to food
concentrations (cells/mL).
0
10
20
30
40
50
60
15 17 19 21 23 25 27 29
Food Concentrations (cells/mL)
VS
C (
mL/
cope
pod/
hr)
Data and the Studies
Top graph redrawn from Frost, 1972.
Bottom graph redrawn from Redrawn from Paffenhofer and Lewis, 1990
unstarved
starved
Phytoplankton Concentration
Ingestion rate
Phytoplankton Concentration
VolumeSwept Clear
Jar Copepod stage Ingestion (cells/copepod/day)
A 2 stage V 8878
D 3 stage V 7463.8
C t1 2 stage V 8101.2
C t2 2 stage V 20382.6
B t1 2 stage IV 850.2
B t2 2 stage IV 1986
THE Salp Invasion! Oh Noes!
Salps asexually reproducing
Is the beginning stage of an upwelling an optimal environment for Salp (Thaliacea) growth?
-Colder temperatures.
-Slight increase in nutrient concentration.
-Little competition with copepods for food.
-Leads to increased Organic Carbon……
Comparison of Animal Density within Cores to Zooplankton within the Water
Column “As a life’s work, I would remember everything-everything, against loss. I would go through life like a plankton net.” – Annie Dillard
-Well, if Annie was to go through life with our plankton net, she would miss a wealth of information. Sampling with our 500 micromesh excluded many of the smaller plankton-an order of magnitude to be precise.
Benthos Animal Density
Total density of fauna in each core per m^2
0.00 200.00 400.00 600.00 800.00 1000.00 1200.00 1400.00
C1
C2
C3
C4
C5
C6
Co
re N
um
ber
Denisty of Fauna (number of animals/m^2)
Mean number of benthic organisms at R2 = 833 individuals / m2.Based on literature values, zooplankton abundance in the water column is at least an order of magnitude greater.
Core Analysis
Cores were taken for fine sediment, chlorophyll, and ammonium analysis
Samples taken every 1 cm for fine sediment and chlorophyll analysis.
Sediment Fines
We might expect lower organic material because of greater mineralization rates
Possible higher levels of inorganic fines because less mixing
Figure 2. Mean fines per gram (+/- one standard deviation) of sediment for the top 15 cm of core samples taken at R2 on June 20, 2008.
0
2
4
6
8
10
12
14
16
0.00 0.50 1.00 1.50 2.00 2.50 3.00 3.50 4.00
Fines dry weight (g)
Dep
th fr
om s
urfa
ce (c
m)
The average ammonia concentration for three cores from time 0 (T0) and three cores from time final (TF).
0
1
2
3
4
5
6
7
8
9
10
11
0.00 50.00 100.00 150.00 200.00 250.00 300.00 350.00 400.00
Ammonia Concentration (μmol/l)
Dep
th (
cm)
T0
TF
Ammonia Concentration within the Pore Water
R. Jahnke et al. 2005.
Late Summer- at 27 meters in SAB
June 2008- at 27meters in SAB
Remineralization Estimates
-Remineralization is highest in the upper cm’s of the sediment.
-Amount of carbon found in the sediment was less than Jahnke’s findings.
0.00 2.00 4.00 6.00 8.00 10.00 12.00 14.00 16.00 18.00 20.00
OLW
0-1
1-2
2-3
3-4
4-5
5-6
6-7
7-8
8-9
9-10
Dep
th (
cm)
Average Remineraliztion rate of Carbon (μmol/l/h)
The data collected by KSU students on the R/V Savannah June 19 and 20th 2008 compared to the data used in the R. Jahnke 2005 paper for the rate of carbon remineralization in sediment cores.
mmol/m^2 day
KSU 6.55
Jahnke 20.5
Organic matter
PrimaryProductivity
CO2
NH4
CO2
NH4
RemineralizationDecompostion
CO2
NH4
>700 mgC/m2/d
679 mgC/m2/d
PrimaryProductivity
78.6 mgC/m2/d
Zooplankton grazinge.g. Eucalanus pileatus only
16 ugC/ind./d WATER COLUMN
BENTHIC SEDIMENTS
CO2
NH4?
An overview of water column and benthos rates
The Water Column and Benthic Interaction An Open and Dynamic
Filtration System
Organic carbon input from the water column (from organisms such as (eucalanus pileatus)+
tidal and current-bottom interactions remineralization
within the sediment by heterotrophic bacteria
inorganic carbon and nitrogen advected back out due to tidal
current-bottom interactions/ripples.
Conclusions
Unusually high feeding for Eucalanus suggesting low food concentration and high abundance of salp support the upwelling hypothesis.
Low rates remineralization relative to primary production suggest that the system is not in steady state. Remineralization rate may increase later as production subsides.
“GOODBYE”