An Ocean Mesocosm ExperimentEvaluation and Results

April 2013James W. Murray

Evelyn LessardBob Morris

Robin KodnerKelsey Gaessner

Mike FoyBarbara PaulAmanda Fay

Molly Roberts

EFANSA

Ocean Acidification impacts on ecosystems

Goals:How does chemistry and biology change:1.with time during bloom conditions?2.with CO2 levels?

As seen from Google Earth (like the Great Wall)The mesocosm dock with its space age domes is circled.

FHL is an HNLC Ocean Area (NO3 = 25 mM; PCO2 = 650 matm)The high nutrient and CO2 water is of natural origin.Source is the California Undercurrent.

3/263/273/283/293/303/31 4/1 4/20

20

40

Dock Nitrate

Series1

Date

Nitr

ate

(mm

ol l-

1)

12/7 1/26 3/17 5/6300500700900

Dock pCO2 (calculated)

pCO2 (calculated)

Date

pCO

2

Rich Thomson (IOS)

April 2012 Experiment

Effect of CO2 amendmentsobscured by a dramatic biological bloom.

Need to try something new!

Nine MesocosmsPolyurethane bags (commercially sealed)Total Length = 6mLength in water = 5m Diameter = 1mNominal volume = 3500 ltr

Mesocosm FramesEach with its own flotation

Mesocosms filled from a common reservoir filled with coarsely filtered seawater

Two important changes from 2012 Experiment1. Light reduction –to slow biology2. CO2 Control – the master variable

Cleaning Mesocosm Bags

Experiment Time PointsFilled mesocosms with filtered (0.5 mm) seawater at ~1 ltr min-1

Friday April 5 to Monday April 8 (50 hours)

April 8 – added 15 ltr of 4M NaCl to each bagMeasured salinity before and after to calculate volume

Added CO2 saturated SW to make six @ 1250 μatm

Controls at 650 μatm; High at 1250 μatm; Drift at 1250 μatm but no CO2 control

Sampled daily for 21 days starting at 800AM.

T0 sampling day on Tuesday April 9.

T10 (April 19) Top screens removed. Side screens lowered

T21 April 30 – last day of sampling

There were cloudy days and sunny days (especially just after T10!

Incoming PAR

Time (days)

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21

PA

R (E

iens

tein

s m

-2 d

-1)

0

10

20

30

40

50

OA Dock Logger

FHL weather stn.

29.029.530.030.531.031.532.032.5

Salinity

M1M2M3M4M5M6M7M8M9Dock

Time (Days)

Salin

ity

0 2 4 6 8 10 12 14 16 18 208.00

8.20

8.40

8.60

8.80

TemperatureM1M2M3M4M5M6M7M8M9Dock

Time (Days)

Tem

pera

ture

(C)

Bag Volume (L)1 33782 28813 30414 3411*5 28926 2396*7 27118 30209 3119 Average = 2983 ± 316 L

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 210

5

10

15

20

25

30

35

NO3

M1M2M3M4M5M6M7M8M9Dock

Time (Days)

NO

3 (m

mol

es L

-1)

106 CO2 + 16 HNO3 + H3PO4 + 122 H2O + trace elements (e.g. Fe)

(CH2O)106(NH3)16(H3PO4) + 138 O2

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 210

50

100

150

200

250

300

350

400

450

500

O2

M1 M2

M3 M4

M5 M6

M7 M8

M9 Dock

Time (Days)

O2

(mm

ol L-

1)

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 210

5

10

15

20

25

30

35

40

Chlorophyll

M1M2M3M4M5M6M7M8M9Dock

Time (Days)

Chlo

roph

yll (

mg

L-1)

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 210

200

400

600

800

1000

1200

1400

1600

1800

2000

pCO2

M1M2M3M4M5M6M7M8M9Dock

Time (Days)

pCO

2 (p

pm)

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 217.2

7.4

7.6

7.8

8

8.2

pH

M1M2M3M4M5M6M7M8M9Dock

Time (Days)

pH

DMS (a greenhouse gas) by Korean Team

The Brilliant 2013 Mesocosm Experiment Team

Ocean 492 – Ocean Acidification Apprenticeship Spring 2013

Porcino, Natsuko "chlorophyll and phytoplankton community changes in a shifting CO2 environment"Stephens, Amy "Phytoplankton Community and Abundance in High CO2 Conditions" Shutt, Kiely "Diaton Silicification changes in a high pCO2 environment: a mesocosm experiment"Newcomb, Daneil "Transparent exopolymer particle production under ocean acidification conditions: a mesocosm study"Baird, Andrew "Constraining Primary Production within a pCO2 Manipulation Mesocosm Experiment"Gravinese, Philip "The effects of elevated pCO2 on microzooplankton: a mesocosm approach"Govenar, Kelly "Phytoplankton Growth and Microzooplankton Grazing with Increased CO2 Levels“Apple, Jennifer “Effects of CO2 Manipulation on Heterotrophic Bacterioplankton: A mesocosm study”

Conclusions:1. Biological Production is limited by nutrients and light. We can control the light to slow biology. Our strategy worked.

2. CO2 is a master variable in OA experiments and should be kept constant. Our DIC addition techniques were successful.

In this experiment we had mesocosms called: Control = 650 matm High = 1250 matm Drift = 1250 matm to 500 matm

3. The results reflect two phases to the experiment T0 to T10 slower biological production T10 to T21 faster biological production

4. Many of the results are “first time” data for the FHL dock