trends in environmental conditions and plankton abundance and composition in the nw atlantic 1)...
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Trends in environmental conditions and plankton abundance and composition in the NW Atlantic
1) Observations from BIO cruises on the AR7W line in the Labrador Sea (1990-2006)
2) Observations from Continuous Plankton Recorder sampling in the southern Labrador Sea and on the Newfoundland and Scotian shelves (1957-2006)
Erica Head
with help from
Kumiko Azetsu-Scott, Glen Harrison, Ross Hendry, William Li, Igor Yashayaev, Philip Yeats
Tem
per
atu
re (
oC
)
SST anomalies relative to 1971-2000
“De-seasoned” 0-50 m temperatures during annual cruises and monthly SST anomalies relative to 1990-2006 averages.
Temperatures increased in all regions of the AR7W line between 1990 and 2006
Trends in temperature along the AR7W line 1990-2006
Sili
cate
(m
mo
l m-3)
Nit
rate
(m
mo
l m-3)
Trends in nutrient levels (60-200 m or 60-bottom on shelves) during annual cruises
Silicate decreased everywhere
Nitrate increased in the central basin and slope waters and decreased on the Greenland Shelf, with no change on the Labrador Shelf
Trends in integrated (0-100 m) or sea surface chlorophyll concentration in the Labrador Sea
Year
94 95 96 97 98 99 00 01 02 03 04 05 06 07 08 09
Ch
loro
ph
yll
(lo
g m
g m-2
)
0
1
2
3
4
Labrador Shelf
b = - 0.03 y-1
r2 = 0.15p = 0.17
Year
94 95 96 97 98 99 00 01 02 03 04 05 06 07 08 09C
hlo
rop
hyll
(lo
g m
g m-2
)0
1
2
3
4
Labrador Basin
b = + 0.009 y-1
r2 = 0.03p = 0.55
Year
94 95 96 97 98 99 00 01 02 03 04 05 06 07 08 09
Ch
loro
ph
yll
(lo
g m
g m-2
)
0
1
2
3
4
Greenland Shelf
b = + 0.015 y-1
r2 = 0.03p = 0.55
In
sit
u i
nte
gra
ted
ch
loro
ph
yll
(M
ay
, J
un
e o
r J
uly
, lo
g m
g m
-2)
0.4
0.6
0.8
1.0
1.2
1998 2000 2002 2004 2006
R2 = 0.18, p = 0.26 0.4
0.6
0.8
1.0
1.2
1998 2000 2002 2004 2006
R2 = 0.41, p = 0.05 0.4
0.9
1.4
1.9
2.4
1998 2000 2002 2004 2006
R2 = 0.02, p = 0.74
Sa
tell
ite
SS
ch
loro
ph
yll
(A
ve
rag
e A
pr.
-Au
g.,
mg
m-3)
Year Year Year
Labrador Shelf
Labrador Shelf
Central Labrador Basin
Central Labrador Sea
Greenland Shelf
Eastern Labrador Sea
R2 = 0.15, p = 0.17 R2 = 0.03, p = 0.55 R2 = 0.03, p = 0.55
Chlorophyll concentrations increased on the Labrador Shelf and in the central basin between 1998 and 2006 and in all regions the spring bloom started earlier.
Trends in phytoplankton groups differentiated by size (upper row, flow cytometry) or pigment composition (lower row, HPLC pigment analysis)
Pic
op
hyt
op
lan
kto
n (
log
cel
ls m
-2)
8
9
10
11
12
13
Sm
all
nan
op
hyt
op
lan
kto
n (
log
cel
ls m
-2)
8
9
10
11
12
13
Year
94 95 96 97 98 99 00 01 02 03 04 05 06
Lar
ge
nan
op
hyt
op
lan
kto
n (
log
cel
ls m
-2)
8
9
10
11
12
13
Labrador Shelf
Pic
op
hyt
op
lan
kto
n (
log
ce
lls
m-2
)
8
9
10
11
12
13
Sm
all
na
no
ph
yto
pla
nk
ton
(lo
g c
ell
s m
-2)
8
9
10
11
12
13
Year
94 95 96 97 98 99 00 01 02 03 04 05 06
La
rge
na
no
ph
yto
pla
nk
ton
(lo
g c
ell
s m
-2)
8
9
10
11
12
13
Labrador Basin
f mic
ro
0.0
0.2
0.4
0.6
0.8
1.0
f na
no
0.0
0.2
0.4
0.6
0.8
1.0
Year
94 95 96 97 98 99 00 01 02 03 04 05 06
f pic
o
0.0
0.2
0.4
0.6
0.8
1.0
f mic
ro
0.0
0.2
0.4
0.6
0.8
1.0
f na
no
0.0
0.2
0.4
0.6
0.8
1.0
Year
94 95 96 97 98 99 00 01 02 03 04 05 06
f pic
o
0.0
0.2
0.4
0.6
0.8
1.0
Large nano-
Micro-Micro-
Large nano-
Small nano-
Nano-
Small nano-
Nano-
Pico- Pico-
Pico-Pico-
No.
of c
ells
Fra
ctio
n of
chl
. in
grou
p
Between 1996 and 2005 the abundance/proportion of large cells decreased and the abundance/proportion of small cells increased on the Labrador Shelf and in the central basin.
Trends in zooplankton dry weight averaged over stations for different regions of the AR7W line (1995-2006)
0
2
4
6
1995
1997
1999
2001
2003
2005
0
2
4
6
1995
1997
1999
2001
2003
2005
0
2
4
68
10
12
14
1995
1997
1999
2001
2003
2005
Data from late May only
Zo
op
lan
kto
n d
ry w
eig
ht
(0-1
00 m
, g
m-2)
C. finmarchicus C. glacialis C. hyperboreus Other zooplankton
0
2
4
6
1995
1997
1999
2001
2003
2005
0
2
4
6
8
1995
1997
1999
2001
2003
2005
0
24
6
8
1012
14
1995
1997
1999
2001
2003
2005
Labrador Shelf Central Labrador Sea Eastern Labrador Sea
All data were collected between late May and late July
Labrador Shelf Central Labrador Sea Eastern Labrador Sea
Zooplankton biomass showed no obvious trend with time, even when data from only one 2-week period of the year was used to eliminate the effect of seasonal dynamics.
Positions where Continuous Plankton Recorder (CPR) samples used in this analysis were collected (1957-2006)
Latit
ude
(o N)
Longitude (oW)
WSSESS
SNL
53-45
45-40
40-35
35-30
30-25
<25
Sampling is supposed to be monthly via ships-of-opportunity but there are gaps.
Before 1991 for the entire line or parts of the line -some months were missed in some yearssome years were missed completely
From 1991-2006, monthly coverage was good
Samples are from ~7 m (near-surface)
Data on plankton abundance were averaged over the areas for a given month and year and then over a given month within a “decade” and finally over all months to give an annual average for each decade.
The “decades” used were 1957-1969, 1970-1979, 1980-1986, 1991-1999, 2000-2006.
0
20000
40000
60000
80000
100000
120000
140000
160000
w ss ess snf 53-45 45-40 40-35 35-30 30-25 <25
0.00
0.20
0.40
0.60
0.80
1.00
1.20
1.40
Diatoms Dinoflagellates PCI
Spatial patterns of phytoplankton abundance
Spatial patterns were calculated by averaging the decadal “annual” averages.
All three indices of phytoplankton abundance were higher west of 45oW than to the east.
Diatoms and the “Phytoplankton Colour Index” (PCI) co-varied and were most abundant in the 53-45oW region, over the Newfoundland Shelf/Slope, in the Labrador Current.
Dinoflagellates were most abundant on the south Newfoundland Shelf.
Dia
tom
/Din
ofl
ag
ell
ate
ab
un
da
nc
e
(Ce
lls
pe
r s
am
ple
)
PC
I (R
elat
ive
abun
dan
ce)
0
20000
40000
60000
80000
100000
120000
140000
160000
180000
200000
1960s 1970s 1980s 1990s 2000s
w ss
ess
snf
53-45
Decadal changes in phytoplankton abundance
West of 45oW East of 45oW
Dia
tom
ab
un
da
nc
e
(Ce
lls
pe
r s
am
ple
)
West of 45oW (i.e. Newfoundland Shelf/Slope, Scotian Shelf) diatom abundance was higher in the 1990s and 2000s than in the 1960s and 1970s.
East of 45oW diatom abundance did not change significantly.
Diatom abundance is shown here, but all three indices of phytoplankton abundance behaved in more-or-less the same way.
0
20000
40000
60000
80000
100000
120000
140000
160000
180000
200000
1960s 1970s 1980s 1990s 2000s
45-40
40-35
35-30
30-25
<25
Diatom abundance
0.0
0.2
0.4
0.6
0.8
1.0
wss ess snl 53-45
40-45
35-40
30-35
25-30
<25
C. glacialis V-VI C. hyperboreus III-VI
020406080
100120140160180
wss ess snl 53-45
40-45
35-40
30-35
25-30
<25
Calanus I-IV C. f inmarchicus V-VI
Spatial patterns of zooplankton abundanceC
ala
nu
s a
bu
nd
an
ce
(N
um
be
r p
er
sa
mp
le)
Young stage Calanus (Calanus I-IV, which are mostly C. finmarchicus) were most abundant over the Newfoundland Shelf/Slope, in the Labrador Current.
Arctic Calanus were most abundant over the Newfoundland Shelf/Slope, in the Labrador Current, but were much less abundant than Calanus I-IV or Calanus finmarchicus.
Arctic Calanus species
0
50
100
150
200
250
300
1960s 1970s 1980s 1990s 2000s
45-40
40-35
35-30
30-25
<25
0
50
100
150
200
250
300
1960s 1970s 1980s 1990s 2000s
WSS
ESS
SNF
53-45
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1960s 1970s 1980s 1990s 2000s
WSS
ESS
SNF
53-45
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1960s 1970s 1980s 1990s 2000s
45-40
40-35
35-30
30-25
<25
Decadal changes in zooplankton abundance
Calanus I-IVWest of 45oW East of 45oW
Calanus hyperboreus III-VI
In the Newfoundland Shelf/Slope waters (53-45oW): • Calanus I-IV (+ C. finmarchicus) abundance was lower in the 1990s and 2000s, than in the 1960s and
1970s.• C. hyperboreus (+ C. glacialis) abundance was higher in the 1990s and 2000s than in the 1960s and 1970s.
Summary
Along the AR7W line between 1995 and 2006:
• Temperatures increased• Nitrate levels increased, silicate levels decreased• The abundance/proportion of large phytoplankton decreased• The phytoplankton bloom started earlier • Calanus finmarchicus reproduction/development occurred earlier
Along the CPR route between 1957 and 2006:
• Phytoplankton abundance was highest in the 53-45oW region (Newfoundland Shelf/Slope waters, in the Labrador Current)
• West of 45oW phytoplankton abundance increased between the 1970s and 1990s.• The abundance of three Calanus categories was highest in the 53-45oW region.• Two Calanus categories are Arctic species and in the 53-45oW region their abundance
increased between the 1970s and the 1990s.• The third category (Calanus I-IV) is a boreal species and its abundance decreased in the 53-
45oW region between the 1970s and the 1990s.• The fourth Calanus category is also a boreal species and it also decreased in abundance in
the 53-45oW region between the 1970s and the 1990s.
The goal of the ESSAS programme:
to compare, quantify and predict the impact of climate variability and global change on the productivity and sustainability of Sub-Arctic marine ecosystems.
Primary Sub-Arctic regions: Sea of Okhotsk, Oyashio, Bering Sea, Hudson Bay, Labrador/ Newfoundland shelves, Gulf of St. Lawrence, West Greenland, Iceland, Nordic Seas, and Barents Sea
There are national programmes in Japan, Iceland and the US and ESSAS is co-ordinating a series of national and international projects in IPY.
Canada is involved with Norway in an international programme (NORCAN) comparing the Barents Sea/Norwegian Sea and Newfoundland/Labrador Shelf/Labrador Sea ecosystems.
The goal of the BASIN programme:
to understand and predict the impact of climate change on key species of plankton and fish, and associated ecosystems and biogeochemical dynamics in the North
Atlantic Subpolar Gyre System and surrounding shelves, in order to improve ocean management and conservation.
The aim is to have a co-ordinated North Atlantic wide programme with the EU and US researchers focussing on the sub-polar gyre and adjacent continental shelves.
Emerging issues: Trans-Arctic invasions?
A species of N Pacific phytoplankton (the diatom Neodenticula seminae) that is common in the Pacific Ocean, but that has been absent from the N Atlantic for 800,000 years has been seen in CPR samples in the NW Atlantic since 1999.
The absence of ice throughout much of the Canadian Arctic archipelago in 1998 may have allowed the species to move east from the Bering Sea, through the archipelago into Baffin Bay and from there south to the Labrador Sea.
Will other species follow?
Locations where CPR samples containing the Pacific diatom Neodenticula seminae have been collected, and collection years.
From Reid et al. (2007)
Scanning electromicrograph of Neodenticula seminae
Emerging issues: Ocean acidification
Trends in TIC and pH (100-500 m) in the Labrador Sea (AR7W line)
2140
2145
2150
2155
2160
2165
1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008
year
To
tal C
O2
con
c. (
µm
ol/k
g)
8.08
8.09
8.10
8.11
8.12
8.13
8.14
8.15
pH
Total CO2
pH
2140
2145
2150
2155
2160
2165
1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008
year
To
tal C
O2
con
c. (
µm
ol/k
g)
8.08
8.09
8.10
8.11
8.12
8.13
8.14
8.15
pH
Total CO2
pH
Tot
al i
nor
gani
c ca
rbon
con
cent
ratio
n (µ
mol
/kg
)
Year
pH
TIC
pH
Total inorganic carbon is increasing – pH is decreasing
Spatial patterns of the abundance of calcifying organisms
Foramnifera (Forams) and Coccolithophores have only been counted since the 1980s, before then there are only presence/absence data. So, the abundance index is the frequency of occurrence in samples.
Forams (microzooplankton) are more often seen to the east of 45oW than to the west.
Coccolithophores (phytoplankton) are most often seen south of Newfoundland or over the Reykjanes ridge.
Limacina spp. (a pteropod, zooplankton species) has always been counted. Here, both frequency of occurrence and abundance show maximum values at 40-35oW.
0.00
0.05
0.10
0.15
0.20
0.25
0.30
WSS ESS SNL 53-45 45-40 40-35 35-30 30-25 <25
0
5
10
15
20
25
30
Forams Coccolithophores Limacina Limacina concs.
Fre
qu
en
cy
of
oc
cu
rre
nc
e
Lim
acin
a ab
und
ance
(No.
pe
r sa
mpl
e)
0.00
0.05
0.10
0.15
0.20
0.25
0.30
0.35
1960s 1970s 1980s 1990s 2000s
WSS
ESS
SNL
53-45
0
10
20
30
40
50
60
70
80
1960s 1970s 1980s 1990s 2000s
WSS
ESS
SNL
53-45
0.00
0.05
0.10
0.15
0.20
0.25
0.30
0.35
1960s 1970s 1980s 1990s 2000s
45-40
40-35
35-30
30-25
<25
0
10
20
30
40
50
60
70
80
1960s 1970s 1980s 1990s 2000s
45-40
40-35
35-30
30-25
<25
Fre
quen
cy o
f oc
curr
enc
e
Lim
acin
a ab
und
ance
(No.
pe
r sa
mpl
e)
Decadal changes in the abundance of Limacina spp.
W of 45oW W of 45oW
E of 45oW E of 45oW
West of 45oW the frequency of occurrence and abundance data generally change in the same sense in the 1960s-1970s and 1990s-2000s, but not over the entire dataset.East of 45oW the frequency of occurrence data shows a decrease west of 30oW: the abundance data does not.
It may be that counting procedures have become more “rigorous” since the 1980s; changes from the 1990s to the 2000s were consistent for both datasets and abundance decreased in most areas.
6 0 5 5 5 0 4 54 5
5 0
5 5
6 0
6 5
Longitude (oW)
Latit
ude
(o N)
A
BC
The Labrador Sea
Filled circles are regular sampling stations on the AR7W line – sampled by physicists, chemists and biologists since 1990 or 1995.
The sampling periods covered during cruises have varied between late May and late July.
The boxes are areas over which STT and SSChl measurements were averaged to represent conditions on/in
A – the Labrador Shelf
B – the Central Labrador Sea
C – the Eastern Labrador Sea
Bathymetry: Grey line – 200 mBlack lines – 1000, 2000 and 3000 m
Trends in the C. finmarchicus Population Development Index in late May, late winter SST (1995-2006) and the timing of the start of the bloom (1998-2006)
0
10
20
30
40
50
1995 1997 1999 2001 2003 20050
10
20
30
40
50
60
70
1995 1997 1999 2001 2003 2005
0
20
40
60
80
100
1995 1997 1999 2001 2003 2005
r2 = 0.03, p = 0.75 r2 = 0.37, p = 0.20
r2 = 0.15, p = 0.44
C. f
inm
arch
icu
s P
DI
(Ab
. CI-
IIIs/
To
tal a
b.,
%)
50
100
150
200
1998 2000 2002 2004 2006
50
100
150
200
1998 2000 2002 2004 200650
100
150
200
1998 2000 2002 2004 2006Day
of
year
wh
en S
SC
hl.
reac
hes
1 m
g m
-3
r2 = 0.35, p = 0.10r2 = 0.14, p = 0. 31r2 = 0.47, p = 0.04
Ave
rag
e S
ST
Mar
.-M
ay (
oC
)
0
1
2
3
4
5
1995 1997 1999 2001 2003 2005
0
1
2
3
1995 1997 1999 2001 2003 20050
1
2
3
1995 1997 1999 2001 2003 2005
r2 = 0.52, p = 0.008r2 = 0.76, p < 0.001 r2 = 0.26, p = 0.09
Labrador Shelf Central Labrador Sea Eastern Labrador Sea
Population Development Index (PDI) = (Sum stages CI-CIII/Sum all stages) x 100
Population development in C. finmarchicus (1995-2006)
PDI (%) = (Sum CI+CII+CIII abundance) x 100 (Total abundance)
Late Early Late Early LateMay June June July July
PD
I (%
)
100
80
60
40
20
0
Lab. Shelf
Central Lab. Sea
Eastern Lab. Sea
Population Development Index (PDI) averaged over all 2 week sampling periods for all sampling years
0
20
40
60
80
100
1995 1997 1999 2001 2003 2005
0
10
20
30
40
50
1995 1997 1999 2001 2003 20050
20
40
60
80
100
1995 1997 1999 2001 2003 2005
0
10
20
30
40
50
1995 1997 1999 2001 2003 2005
Labrador Shelf
CentralLabrador Sea
EasternLabrador Sea
PD
I in
late
May
(%
)
PDI in late May in individual sampling years
PDI increased
PDI increased
PDI decreased
Increasing temperatures and earlier spring blooms lead to earlier reproduction and faster development in C. finmarchicus populations.