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

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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

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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”