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Transcript of > Inner Transitional Outer PWS 1.Large zooplankton were collected with 1-m2 square MOCNESS with 500 ...
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Inner
Transitional
Outer
PWS
GLOBEC LTOP cruises in the northern GOA.
Month
Year Mar Apr May July Aug Oct
1997 X
1998 X X X X X
1999 X X X X X
2000 X X X X X
2001 X X X X X X
2002 X X X X X X
2003 X X X X X X
2004 X X X X
1. Large zooplankton were collected with 1-m2 square MOCNESS with 500 m mesh. Samples collected in 20 m depth increments from 100 m to the surface at night.
2. Small zooplankton were collected with a 25 cm diameter CalVET net with 150 m mesh. Vertical tows from 100 m to surface during the day.
3. Water column profiles were collected with a Seabird model 911 plus CTD and fluorometer.
4. Samples were collected during years and months listed below:
Collection Sites:1) 13 Stations along Seward Line (labeled GAK)2) 5 Stations in Prince William Sound (PWS box)3) 4 Stations at Hinchinbrook Entrance (HE)
N. plumchrus & N. flemingeri
Month
Mar Apr May Jun Jul Aug Sep Oct
Mea
n A
bund
ance
(N
o. m
-3)
0
20
40
60
80
100
120
140
160
180
InnerTransOuterPWS
Mean Abundance (No. m-3)
0.0 0.5 1.0 1.5 2.0 2.5
Dep
th (
m)
-120
-100
-80
-60
-40
-20
0
Oithona similis
Month
Mar Apr May Jun Jul Aug Sep Oct
Mea
n A
bund
ance
(N
o. m
-3)
0
500
1000
1500
2000
2500
3000
3500
InnerTransOuterPWS
Animals widely distributed across the shelf tend to occur in the upper mixed layer day and night
Neocalanus cristatus
Month
Mar Apr May Jun Jul Aug Sep OctM
ean
Abu
ndan
ce (
No.
m-3
)
0
5
10
15
20
25InnerTransOuterPWS
Mean Abundance (No. m-3)
0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6
Dep
th (m
)
-120
-100
-80
-60
-40
-20
0
Eucalanus bungii
Month
Mar Apr May Jun Jul Aug Sep Oct
Mea
n A
bund
ance
(N
o. m
-3)
0
10
20
30
40
50
InnerTransOuterPWS
Mean Abundance (No. m-3 X 10-1)
0 1 2 3 4 5 6 7
Dep
th (
m)
-120
-100
-80
-60
-40
-20
0
Calanus marshallae
Month
Mar Apr May Jun Jul Aug Sep Oct
Mea
n A
bund
ance
(N
o. m
-3)
0
10
20
30
40
50
60
InnerTransOuterPWS
Mean Abundance (No. m-3)
0.0 0.2 0.4 0.6 0.8 1.0 1.2
Dep
th (m
)
-120
-100
-80
-60
-40
-20
0
Pseudocalanus spp.
Month
Mar Apr May Jun Jul Aug Sep Oct
Mea
n A
bund
ance
(N
o. m
-3)
0
1000
2000
3000
4000
5000
InnerTransOuterPWS
Animals restricted to the outer or inner shelf tend to occur between the thermocline and permanent halocline
Ostracods
Month
Mar Apr May Jun Jul Aug Sep Oct
Mea
n A
bund
ance
(N
o. m
-3)
0
2
4
6
8
10
12
14
InnerTransOuterPWS
Mean Abundance (No. m-3 X 10-1)
0.0 0.5 1.0 1.5 2.0 2.5 3.0
Dep
th (m
)
-100
-80
-60
-40
-20
0
Pasiphaea pacifica
Month
Mar Apr May Jun Jul Aug Sep Oct
Mea
n A
bund
ance
(N
o. m
-3)
0.00
0.01
0.02
0.03
0.04
0.05
0.06
0.07
InnerTransOuterPWS
Mean Abundance (No. m-3 X 10-5)
0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6
Dep
th (m
)
-100
-80
-60
-40
-20
0
Pareuchaeta elongata
Month
Mar Apr May Jun Jul Aug Sep Oct
Me
an
Ab
un
da
nce
(N
o.
m-3 )
0
2
4
6
8
InnerTransOuterPWS
Mean Abundance (No. m-3 X 10-1)
0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8
Dep
th (m
)
-120
-100
-80
-60
-40
-20
0
Cyphocaris challengeri
Month
Mar Apr May Jun Jul Aug Sep Oct
Me
an
Ab
un
da
nce
(N
o.
m-3
)
0
1
2
3
4
5
6
7
InnerTransOuterPWS
Mean Abundance (No. m-3 X 10-3)
0 2 4 6 8 10
Dep
th (
m)
-120
-100
-80
-60
-40
-20
0
Animals which avoid the upper mixed layer, even at night, occur primarily in the fjord
Thysanoessa spinifera
Month
Mar Apr May Jun Jul Aug Sep Oct
Mea
n A
bund
ance
(N
o. m
-3)
0.0
0.2
0.4
0.6
0.8
1.0
InnerTransOuterPWS
Mean Abundance (No. m-3 X 10-2)0 2 4 6 8 10
Dep
th (m
)
-120
-100
-80
-60
-40
-20
0
Euphausia pacifica
Month
Mar Apr May Jun Jul Aug Sep Oct
Mea
n A
bund
ance
(N
o. m
-3)
0.0
0.5
1.0
1.5
2.0InnerTransOuterPWS
Mean Abundance (No. m-3 X 10-2)0 1 2 3 4 5 6 7
Dep
th (
m)
-120
-100
-80
-60
-40
-20
0
Metridia pacifica
Month
Mar Apr May Jun Jul Aug Sep Oct
Mea
n A
bund
ance
(N
o. m
-3)
0
50
100
150
200
250
300
InnerTransOuterPWS
Mean Abundance (No. m-3)
0 5 10 15 20 25 30 35
Depth
(m
)
-120
-100
-80
-60
-40
-20
0
Thysanoessa inermis
Month
Mar Apr May Jun Jul Aug Sep Oct
Mea
n A
bund
ance
(N
o. m
-3)
0.0
0.2
0.4
0.6
0.8
1.0
InnerTransOuterPWS
Mean Abundance (No. m-3 X 10-2)
0.0 0.2 0.4 0.6 0.8 1.0 1.2
Dep
th (
m)
-120
-100
-80
-60
-40
-20
0
Diurnal vertical migrators, residing in the upper mixed layer at night and below the permanent halocline during the day tend to be more abundant on the inner shelf (except E. pacifica)
N. plumchrus & N. flemingeri
Month
Mar Apr May Jun Jul Aug Sep Oct
Mea
n A
bund
anc
e (
No
m3 )
-20
0
20
40
60
80
100
120
140
160
180
199719981999200020012002
Neocalanus, an oceanic species, was more abundant in 1998 and 2002 than in 2000 and 2001 (error bar are 95% confidence intervals)
Correlation between major water column properties and abundance of Neocalanus plumchrus-flemingeri during May, 1998 – 2002; outer nine stations
Upper Mixed Temperature 0.025283
Lower Mixed Temperature 0.421468
Mean Water Column Temperature 0.343750
Potential Energy (Stability) -0.223003
Upper Mixed Salinity -0.757058
Lower Mixed Salinity -0.768888
Mean Salinity -0.783464
Total Redundancy: 63%; Canonical R: 0.79; p = 0.0000027
Neocalanus are negatively correlated to salinity, contrary to expectations for an oceanic species (station outside the ACC)
2001
Distance (km)
0 50 100 150 200
Abu
ndan
ce (
No
m3 )
0
100
200
300
400
500
OTHERSCalanus marshallaeEucalanus bungiiMetridia spp.Neocalanus cristatusN. plumchrus & N. flemingeri
2000
0 50 100 150 2000
100
200
300
400
500
0 5 0 1 0 0 1 5 0 2 0 0
D ista n ce (k m )
-1 0 0
-8 0
-6 0
-4 0
-2 0
0
Dep
th (
m)
0 5 0 1 0 0 1 5 0 2 0 0
-1 0 0
-8 0
-6 0
-4 0
-2 0
0
Dep
th (
m)
30.4
30.8
31.1
31.5
31.8
32.2
32.6
32.9
33.3
33.6
Salinity and Copepod abundance; Seward Line; MayLine is 32.4
Neocalanus populations were low when oceanic water occurs on the shelf, confining brackish water to the ACC
30.4
30.8
31.1
31.5
31.8
32.2
32.6
32.9
33.3
33.6
Salinity and Copepod abundance; Seward Line; MayLine is 32.4
Neocalanus populations were high when low-salinity water is mixed across the shelf to the shelf break or beyond (color key in right panel)
2002
Distance (km)
0 50 100 150 2000
100
200
300
400
500 1998
0 50 100 150 200
Abu
ndan
ce (
No
m3 )
0
100
200
300
400
500
0 5 0 1 0 0 1 5 0 2 0 0
-1 0 0
-8 0
-6 0
-4 0
-2 0
0
Dep
th (
m)
0 5 0 1 0 0 1 5 0 2 0 0 2 5 0
D ista n ce (k m )
-1 0 0
-8 0
-6 0
-4 0
-2 0
0
Dep
th (
m)
March, April, August 1999
29.530
30.531
31.532
32.533
33.534
34.535
0 5 10 15 20 25 30 35 40 45 50
NO3 (um/l)
Sa
lin
ity
(p
su
)
From a poster at ASLO, 2000, by Childers, Whitledge, Stockewll, Weingartner, Danielson, Coyle: Major nutrient distributions in relation to the physical structure of the Gulf of Alaska shelf.
Nitrate is on average positively correlated to salinity
4 0 4 2 4 4 4 6 4 8 5 0 5 2 5 4 5 6 5 8
L a t i t u d e ( d e g r e e s )
-500
-400
-300
-200
-100
Dep
th (
m)
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
Iron concentrations (nmol/kg) from Ocean Station P to the Gulf of Alaska shelf break (Martin et al., 1989)
Iron concentrations in the euphotic zone are very low from ocean station P in the central Gulf of Alaska gyre
northward to the self break off Seward Alaska
Wu, Jingfeng: measured iron on the Seward Line in the upper mixed layer during May, 2004
Iron concentrations (Wu, personal communication)
0
0.5
1
1.5
2
2.5
3
3.5
4
4.5
5
0 50 100 150 200 250
Distance (km)
nmol
kg
-1
Iron concentration in the euphotic zone increased across the shelf from minimal values near the shelf break to maximum values in the Alaska Coastal Current
Summary of observations1) Copepod abundance is strongly and negatively
correlated to salinity.2) Copepod abundance shows little or negative correlation
to water column stability.3) Copepod abundance shows little or no correlation to
upper mixed temperatures.4) When copepod abundance is low, intrusion of oceanic
water onto the shelf constrains the mixing zone to a narrow band near the outer edge of the coastal current.
5) When copepod abundance is high, the mixing zone is spread across the shelf from the coastal current to the shelf break front.
6) Macronutrient concentrations are positively correlated to salinity.
7) Iron concentrations are near threshold detection levels in the mixed layer at the shelf break but about an order of magnitude higher in the Alaska Coastal Current (ACC).
Cross Shelf Distribution of Major Zooplankton Species Relative to Depth Distribution (bar graph insets)
Animals which occur in the upper mixed layer day and night are moved back and forth across the shelf in the wind-mixed layer (Oithona, Neocalanus plumchrus / flemingeri)
Animals residing between the thermocline and permanent halocline tend to be separated on the shelf (Neocalanus cristatus, Eucalanus bungii, Calanus marshallae, Pseudocalanus).
Diurnal vertical migrators, residing below the halocline during the day and above the thermocline at night are apparently avected shoreward in the bottom layer and tend to concentrate on the inner shelf (Metridia spp., Euphausiids)
Mesopelagic animals that occur below the thermocline, even at night are apparently advected shorward in the bottom layer and tend to concentrate in the fjord system of Prince William Sound (Cyphocaris challengeri, Pasaphaea pacifica, Pareuchaeta elongata, pelagic ostracods)
Summary of Distribution
Methods
Introduction: Zooplankton abundance and distribution on the northern Gulf of Alaska shelf are tightly linked to physical processes influencing production and advection of water on and off the shelf. A primary goal of the LTOP project was to document the cross shelf distribution and abundance of major zooplankton taxa relative to water mass movements and to elucidate processes leading to interannual differences is abundance. This poster illustrates cross shelf distribution of major zooplankton species relative to their depth distribution and water mass movements. Contrary to expectation, the abundance of Neocalanus flemingeri, an oceanic species, is negatively correlated to salinity. The abundance-salinity correlation and interannual differences in Neocalanus abundance are related to physical processes, potentially influencing production.Acknowledgments: This research was conducted on the R. V. Alpha Helix. Technical support was provided by the captain, crew and ships technicians (Steve Hartz, Brian Rowe, Dave Aldridge and Dan Mahalck). Aid in sample processing and data entry was provided by Chris Stark, Janet Ballek and Elizabeth Stockmar. The research was multidisciplinary, involving the cooperation of a number of researchers and institutions. They include: Tom Royer, Old Dominion University; Amy Childers, Tom Weingartner, Seth Daniels, Steve Okkonen, Dean Stockwell and Terry Whitledge, University of Alaska Fairbanks. We thank all of the above for their participation in this research effort. The Long Term Observation Program was funded by US GLOBEC award number NA67RJ0147AMD7
Distribution and abundance of zooplankton on the northern Gulf of Alaska shelf relative to water massesKenneth O. Coyle; School of Fisheries and Ocean Science, University of Alaska, Fairbanks Alaska
Interannual Differences in Abundance of Neocalanus flemingeri
Hypothesis: The most likely explanation for the observations is that horizontal mixing between high-nutrient, low-iron oceanic water and high-iron, low-nutrient ACC water promotes elevated primary production in the mixing zone, leading to elevated production of zooplankton grazers.
N. plumchrus & N. flemingeri
Month
Mar Apr May Jun Jul Aug Sep Oct
Mea
n A
bund
anc
e (
No
m3 )
-20
0
20
40
60
80
100
120
140
160
180
199719981999200020012002
Neocalanus, an oceanic species, was more abundant in 1998 and 2002 than in 2000 and 2001 (error bar are 95% confidence intervals)