Pelagic Ecosystem CO Enrichment Study -The copepods point of view-

choppedspleenMechanics

Feb 21, 2014 (3 years and 5 months ago)

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Pelagic Ecosystem CO
2

Enrichment Study

-
The copepods point of view
-



S.Jansen
1
, U.Bathmann
1
, U.Riebesell
2

1
Alfred Wegener Instiute for Polar and Marine Research, Bremerhaven, Germany;
2
Leibniz Institut für Meereswissenschaften IFM
-
GEOMAR, Kiel, Germany

2

4

6

8

10

12

1

2

3

4

2

4

6

8

10

2

4

6

8

10

12

24

36

48

60

Mesocosm 1

Mesocosm 4

Mesocosm 7

t

t

t

µg Chl a / l

4

6

8

10

12

14

16

18

20

0


30


60


90

120

150

180

210

4

6

8

10

12

14

16

18

20

4

6

8

10

12

14

16

18

20

Mesocosm 1

Mesocosm 4

Mesocosm 7

The

aim

of

the

study

was

to

examine

effects

of

different

CO
2

concentrations

on

a

natural

plankton

community

during

the

course

of

a

diatom

bloom
.

In

a

total

of

9

mesocosms

the

seawater

carbonate

system

was

manipulated

to

achieve

3

different

CO
2

levels

with

3

replicates

each
.

A

detailed

description

of

the

experimental

setup

is

given

in

a

poster

by

Riebesell

at

al
.

(this

session)
.


With

the

focus

on

mesocosm

1

(
Year

2100
-
),

4

(
present
-
)

and

7

(
Glacial
-

atmospheric

CO
2

level)

the

zooplankton

abundance

was

determined

and

a

number

of

egg

and

fecal

pellet

production

experiments

were

performed

throughout

the

3

weeks

of

the

experimenal

setup

in

Bergen,

Norway
.

Fecal pellet production experiments

Fecal pellet carbon (FPC) sedimentation

Zooplankton Abundance

Egg production of
Calanus finmarchicus

Mesocosm 1

Nauplien

Calanus


other calanoid copepods

Oithona

other zooplankton

Mesocosm 4

Mesocosm 7

Individuals / liter

Start

t0

t9

t14

Start

t0

t9

Start

t0

t9

t14

0

1

2

3

4

5

6

7

Start

t0

t9

t14

0

10

20

30

40

50

Start

t0

t9

t14

Start

t0

t9

Mesocosm 1

Mesocosm 4

Mesocosm 7

µg C / liter

Zooplankton

abundance

was

determined

in

the

beginning

of

the

experiment
.

Additionally

net

samples

were

taken

3

times

during

the

experiment

with

a

small

zooplankton

net

(
9
,
3

cm

diameter
;

90
µm

mesh

size)

from

8
-
0

meter
.

Zooplankton

was

classified,

size

was

measured

and

convered

into

carbon
.

Calanus

finmarchicus

made

up

for

the

largest

part

of

zooplankton

carbon

in

all

mesocosms

for

the

first

10

days
.


7

8

9

10

11

0

20

40

60

80

100

7

8

9

10

11

7

8

9

10

11

20

40

60

80

100

120

Mesocosm 1

Mesocosm 4

Mesocosm 7

t

t

t

Incubation

water

for

the

experiments

was

taken

from

mesocosm

1
,

4

and

7
.

C
.

finmarchicus

was

incubated

for

24

hours

at

constant

temperature

and

dim

light
.

Egg

production

rate

was

determined

after

24

hours

and

eggs

were

incubated

for

additional

48

hours

for

hatching
.


Egg

production

rate

and

hatching

success

of

C
.

finmarchicus

was

very

high

throughout

the

hole

experiment
.

Fecal

pellet

production

of

C
.

finmarchicus

was

determined

in

the

laboratory

at

5

times

througout

the

mesocosm

experiment
.

Fecal

pellets

were

counted

under

the

binocular
.

Length

and

diameter

of

the

fecal

pellets

were

measured

and

volume

and

fecal

pellet

carbon

was

calculated
.

Fecal pellet production was converted into „ingested carbon“
(Nejstgaard et al. 2001)



~ 20 µgC Copepod
-
1

day
-
1

were ingested by one
C. finmarchicus
.

Produced fecal pellet carbon: 1


4 µgC Calanus
-
1

day
-
1

Sediment

traps

from

the

mesocosms

were

retrieved

and

splitted

ten

times

during

the

experiment
.

Length

and

diameter

of

sedimented

fecal

pellets

were

measured

and

volume

was

converted

into

carbon

(mgC

m
-
2

d
-
1
)
.



FPC sedimentation ranges between 30


150 mgC
m
-
2

d
-
1

t

t

t

Maximum

C
.

finmarchicus

biomass

was

reached

in

the

beginning

of

the

experiment

with

more

than

45

µg

C

/

liter
.


Fig.1: Development of the zooplankton community in the first 14 days of the experiment.

Fig.2: Results of the egg production and egg hatching experiments of
Calanus finmarchicus
. Experiments

were performed in the lab with water from three different mesocosms.

Fig.3: Results from the fecal pellet production experiment (
Calanus finmarchicus
). Incubation water was taken

from the mesocosms. Chlorophyll concentration from the incubation water is indicated.

Fig.4: Fecal pellet carbon (FPC) sedimentation over the three weeks of the mesocosm experiment.

Calanus
sp.