Transcript NW Georges Bank Salinity Anomaly (0-30m)

NW Georges Bank Salinity Anomaly (0-30m)
0.5
0.0
-0.5
-1.0
1975
1980
1985
1990
1995
2000
Broad Scale Chlorophyll vs Salinity – Ted Durbin
2
Jan
1.5
Feb
Chlorophyll
1
Mar
Apr
0.5
May
June
0
-0.5
-1
y = -36.961x + 0.000 r 2 = 0.180
-1.5
-0.015 -0.01 -0.005
0
Salinity
0.005
0.01
0.015
Normalized deviations of
Georges Bank monthly mean
salinity vs chlorophyll. The
slope is significantly different
from zero, p<0.01. There was
no significant relation
between temperature and
chlorophyll, or between
temperature and salinity
(p>0.05).
Broad-scale copepod summary – Ted Durbin
Interannual Variability: All of the dominant copepods on Georges Bank show similar
patterns of variability between years.
3
Mean
Seasonal mean Georges Bank
normalized deviations of the total
population of each of the dominant
copepods for each year together with
the overall mean for the total
Mean Normalized Deviation
Calanus
Pseudocalanus
2
Centropages
Oithona
copepod population.
Temora
1
Metridia
0
-1
1994
1995
1996
1997
1998
1999
2000
Larval Growth Rates vs Prey – Larry Buckley & Ted Durbin
Pseudocalanus Prey for 7 mm Cod
Cod
Haddock
96
98
95
97
99
R esidual Grow th d( - 1)
0 .0 2
0 .0 1
0 .0 0
-0 . 0 1
-0 . 0 2
Haddock 4.5 –7 mm
-0 . 0 3
r2 = 0.58 p<0.01
-0 . 0 4
-1 . 0 0
-0 . 6 0
-0 . 2 0
0 .2 0
0 .6 0
Normalized Residual Prey
1 .0 0
Broad-scale larval analyses:
12
10
Haddock
Cod
8
Early larval mortality rate (ppd)
6
4
2
0
1994
1995
1996
1997
1998
1999
2000
10
8
Early Larval Mortality
Early larval mortality rate
(cod and haddock) vs
Salinity anomaly
6
4
2
0
-1.2
-1.0
-0.8
-0.6
Salinity Anomaly
(…and survivorship correlated with recruitment)
-0.4
-0.2
0.0
GB Salinity Anomaly vs Gulf Stream Position
250
0.5
300
0.0
350
400
-0.5
450
-1.0
-1.5
1992
500
1994
1996
1998
2000
2002
(Gulf Stream position from Tom Rossby)
Connections from:
Physical conditions
to Chlorophyll
to Zooplankton
to Larval growth and survival
to Recruitment
Physical conditions reflecting the ocean’s response
to climate scale forcing
GLOBEC!
No dynamics yet – go back to the beginning:
what’s up with the salinity?
0.5
0.0
-0.5
-1.0
1990 1992 1994 1996 1998 2000 2002
Gulf of Maine Inflows
44.5
44.5
44
44
43.5
43.5
43
43
42.5
42.5
42
42
41.5
41.5
41
41
40.5
40.5
40
-71
40
-71
-70.5
-70
-69.5
-69
-68.5
-68
-67.5
-67
-66.5
-66
-65.5
-65
1976-1979
-64.5
-70.5
-70
-69.5
-69
-68.5
-68
-67.5
-67
-66.5
-66
-65.5
-65
-64.5
-64
-64
1993-1996
More inflow of water from the Scotian Shelf (…lower in salinity)
during the 1990’s (i.e., not originating locally – but coming from
outside the region)
GoM Salinity Anomaly (0-30m)
1
0
-1
GBas
1975
1980
1985
1990
1995
2000
1980
1985
1990
1995
2000
1985
1990
1995
2000
1985
1990
1995
2000
1
0
-1
JBas
1975
1
0
-1
WBas
1975
1980
1
0
-1
GBnk
1975
1980
Wilkinson Basin Temperature 150-200m
8
7
MARMAP – filled circles
1990’s
– open circles
6
5
4
0
100
200
300
Calendar Day
Low surface layer salinities shut down
winter convective cooling
Temp Anomaly (150-200m)
3
2
1
0
R2 = 0.68
-1
-1.5
-1.0
-0.5
0.0
0.5
1.0
Salinity Anomaly (0-30m)
(Taylor and Mountain, submitted)
April Chlorophyll in Wilkinson Basin
(from SEAWIFS, courtesy of J. O’Reilly)
3.4
3.2
3.0
April Chlorophyll
2.8
2.6
2.4
2.2
2.0
1.8
1.6
1.4
-1.5
-1.0
-0.5
Surface Salinity Anoamly
0.0
0.5
OK, still – where is it coming from?
NW Georges Bank Salinity Anomaly (0-30m)
Salinity Anomaly
1.0
0.5
0.0
-0.5
-1.0
1975
1980
1985
1990
1995
2000
Year
O18 analysis indicates the low salinity in the 1990’s is from high latitude.
NW Georges Bank Salinity Anomaly (0-30m)
Salinity Anomaly
1.0
0.5
0.0
-0.5
-1.0
1975
1980
1985
1990
Year
1995
2000
Labrador Current Transport
(shifted one year)
And Georges Bank Salinity Anomaly
0.5
ds
0.0
3.0
-0.5
3.2
-1.0
1994
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004
2005
2006
lctsmooth
2.8
Could the changes we have seen on Georges Bank
be related to the changes in the Arctic and in the
large-scale North Atlantic Ocean?
A direct connection between climate change
and the Georges Bank ecosystem (?)
3 Questions:
Is influence of the low salinity through:
physics (i.e., stratification/mixing)?
nutrients?
resident plankton populations?
some combination of these?
Where is the influence of the low salinity occurring:
in the Gulf of Maine and result transported to GB?
on Georges Bank itself?
both in the GoM and GB?
What is the origin of the low salinity event?
Is it related to changes in the Arctic?
Was it progressive & episodic through the 90’s
(connection to the Arctic gives us a
seat at the Climate Change table)