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Variable patterns in pteropod abundance between the shelf and slope from two decades of observations off
Newport Oregon, USA
Jennifer L. Fisher1, Bill Peterson2, Hongsheng Bi3, Brandon Chasco2 1Cooperative Institute for Marine Resources Studies, Oregon State University, Newport, OR , USA
2NOAA, Northwest Fisheries Science Center, Hatfield Marine Science Center, Newport, OR, USA 3University of Maryland, Center for Environmental Science, USA
Our study region is influenced by large-scale and local physical forcing
Alaska
BritishColumbia
U.S.A.
Alaska
BritishColumbia
U.S.A.Local Conditions Upwelling Coastal currents
ENSO
PDO NPGO
North America
Upwelling regions are particularly susceptible to ocean acidification as upwelling delivers CO2-rich water
onto the continental shelf
From the Seattle Times- Mark Nowlin
Upwelling regions have reduced habitat with respect to aragonite saturation
• High CO2 water that upwells onto the shelf has a low saturation value with respect to aragonite (Ωar)
• When Ωar <1 the water is undersaturated (or corrosive) and marine organisms with CaCO3 shells are susceptible to dissolution
From Feely et al. 2008
The fraction of water column that is corrosive has increased since the pre-industrial era
From Bednarsek at al. 2014
Severe shell dissolution was observed in regions with corrosive water
From Bednarsek at al. 2014
Shelf
Slope
Objectives of this study 1. Determine the seasonal and
inter-annual patterns of aragonite saturation and Limacina sp. on the shelf and slope
2. Investigate whether patterns in Limacina sp. abundance are correlated with aragonite saturation or other environmental parameters
3. Develop a model with a suite of environmental parameters that best characterize changes in Limacina sp. abundance
Methods
Newport Hydrographic
Line
Washington
Oregon
Columbia River
Cape Blanco
NH-25 300 m
NH-5 60 m
• Newport Hydrographic Line • Sampled biweekly/monthly 1996-
present • 2 stations
• Shelf- NH-5 (60 m) • Slope NH-25 (300 m)
• Pteropod collections • Limacina helicina • ½ m vertical net (202-um) • upper 100 m or 2 m off the bottom
• Aragonite saturation • Derived from CTD- temperature and
oxygen (Juranek et al. 2009) • 2006 – present (most consistent)
• Time series analysis and GLM • Determine seasonal and long term
trends (decompose in R) • Quantify effect of environmental
variables on pteropod density
Summer upwelling stronger on the shelf compared to the slope
Upper 100 m temperature slope- NH-25
Month
1 2 3 4 5 6 7 8 9 10 11 12
deg
C
8
9
10
11
Water column (60 m) temperature shelf- NH-5
Month
1 2 3 4 5 6 7 8 9 10 11 12
deg
C
8
9
10
11Slope station Shelf station
Slope station
Shelf station
More suitable habitat on the slope compared to the shelf
More suitable pteropod habitat on the slope compared to the shelf
Limacina helicina density- slope (NH-25)
Month1 2 3 4 5 6 7 8 9 10 11 12
Den
sity
(no.
m-3
± 1
SE
)
0
10
20
30
40
50
60Limacina helicina density- shelf (NH-5)
Month1 2 3 4 5 6 7 8 9 10 11 12
Den
sity
(no.
m-3
± 1
SE
)
0
10
20
30
40
50
60
Percent of upper 100 m corrosive- slope (NH-25)
Month1 2 3 4 5 6 7 8 9 10 11 12
unde
rsat
urat
ed w
ater
(%)
0
20
40
60
80Slope station
Percent of water column (60 m) corrosive- shelf (NH-5)
Month1 2 3 4 5 6 7 8 9 10 11 12
unde
rsat
urat
ed w
ater
(%)
0
20
40
60
80Shelf station
Percent of water column (60 m) corrosive- shelf (NH-5)
Month1 2 3 4 5 6 7 8 9 10 11 12
unde
rsat
urat
ed w
ater
(%)
0
20
40
60
80
100
Percent of upper 100 m corrosive- slope (NH-25)
Month1 2 3 4 5 6 7 8 9 10 11 12
unde
rsat
urat
ed w
ater
(%)
0
10
20
30
40
50
60
Patterns of undersaturated water consistent between 2011 (Bednarsek
et al. 2014) and present study
During peak period of undersaturation % individuals encountering sever dissolution:
Shelf = 75% Slope = 25%
From Bednarsek at al. 2014
Long term trends in Limacina helicina
Shelf- NH-5
Year
96 97 98 99 00 01 02 03 04 05 06 07 08 09 10 11 12 13 14 15 16 17 18
Log1
0 de
nsity
no.
/m3
0.0
0.5
1.0
1.5
2.0
2.5
3.0
Slope- NH-25
Year
96 97 98 99 00 01 02 03 04 05 06 07 08 09 10 11 12 13 14 15 16 17 18
Log1
0 de
nsity
no.
/m3
0.0
0.5
1.0
1.5
2.0
2.5
3.0
Shelf- NH-5
Year
96 97 98 99 00 01 02 03 04 05 06 07 08 09 10 11 12 13 14 15 16 17 18
Log1
0 de
nsity
no.
/m3
0.0
0.5
1.0
1.5
2.0
2.5
3.0
Slope- NH-25
Year
96 97 98 99 00 01 02 03 04 05 06 07 08 09 10 11 12 13 14 15 16 17 18
Log1
0 de
nsity
no.
/m3
0.0
0.5
1.0
1.5
2.0
2.5
3.0Slope- NH-25
Year
96 97 98 99 00 01 02 03 04 05 06 07 08 09 10 11 12 13 14 15 16 17 18
Log1
0 de
nsity
no.
/m3
0.0
0.5
1.0
1.5
2.0
2.5
3.0
Tren
d
0.00.20.40.60.81.01.21.4
Shelf- NH-5
Year
96 97 98 99 00 01 02 03 04 05 06 07 08 09 10 11 12 13 14 15 16 17 18
Log1
0 de
nsity
no.
/m3
0.0
0.5
1.0
1.5
2.0
2.5
3.0
Tren
d
0.00.20.40.60.81.01.21.4
Long term trends in Limacina helicina
Slope- NH-25
Year
96 97 98 99 00 01 02 03 04 05 06 07 08 09 10 11 12 13 14 15 16 17 18
Tren
d Li
mac
ina
no. /
m3
0.2
0.4
0.6
0.8
1.0
Shelf- NH-5
Year
96 97 98 99 00 01 02 03 04 05 06 07 08 09 10 11 12 13 14 15 16 17 18
Tren
d Li
mac
ina
no. /
m3
0.00.20.40.60.81.01.21.4
Long term trends in Limacina helicina
Slope- NH-25
Year
96 97 98 99 00 01 02 03 04 05 06 07 08 09 10 11 12 13 14 15 16 17 18
Tren
d Li
mac
ina
no. /
m3
0.2
0.4
0.6
0.8
1.0
% u
nder
satu
rate
d
0
5
10
15
20
25
30
Long term trends in Limacina sp. on the slope correlated with % of water column undersaturated
Slope- NH-25
Year
96 97 98 99 00 01 02 03 04 05 06 07 08 09 10 11 12 13 14 15 16 17 18
Tren
d Li
mac
ina
no. /
m3
0.2
0.4
0.6
0.8
1.0
% u
nder
satu
rate
d
0
5
10
15
20
25
30% undersaturated
r = -0.43 +7 mo. lag
Slope- NH-25
Year
96 97 98 99 00 01 02 03 04 05 06 07 08 09 10 11 12 13 14 15 16 17 18
Tren
d Li
mac
ina
no. /
m3
0.00.20.40.60.81.01.21.4
NPG
O
-3
-2
-1
0
1
2
3
NPGO r = -0.33 0 mo. lag
NPGO is correlated to upwelling source waters in this region (JO Peterson et al. 2013)
Shelf- NH-5
Year
96 97 98 99 00 01 02 03 04 05 06 07 08 09 10 11 12 13 14 15 16 17 18
Tren
d Li
mac
ina
no. /
m3
0.00.20.40.60.81.01.21.4
% u
nder
satu
rate
d
0
10
20
30
40
50
Long term trends in Limacina sp. on the shelf variable and not correlated with aragonite or NPGO
Shelf- NH-5
Year
96 97 98 99 00 01 02 03 04 05 06 07 08 09 10 11 12 13 14 15 16 17 18
Tren
d Li
mac
ina
no. /
m3
0.00.20.40.60.81.01.21.4
NPG
O
-4-3-2-10123
Generalized Linear Model preliminary results
working towards zero-inflated model
Slope- NH-25 Shelf- NH-5
Effect
Year * *
Month * *
% water Ω<1 * *
NPGO * *
PDO -- --
ONI -- --
Limacina sp. decreases rapidly in response to the fraction of the water column that is corrosive
Limacina sp. decreases rapidly in response to the fraction of the water column that is corrosive
Summary- nearshore • Shelf dominated (80%) by
corrosive water seasonally creating habitat unsuitable for Limacina sp.
• Limacina sp. abundance drops dramatically when the shelf waters are most corrosive
• Long term trends in Limacina sp. abundance not correlated with other variables
• Suitable habitat available during most of the year, with corrosive water occupying 30% of the upper 100 m during July - Oct
• Limacina sp. abundance peaks in May when the water is not corrosive
• Long term trends in pteropod abundance are correlated with the % of the water column undersaturated and with the NPGO
Summary- offshore
• Limacina sp. do not appear to be declining over the 20-year time series
• However, Limacina sp. abundance appears to be strongly influenced by the fraction of the water column that is corrosive
• Future ocean conditions with increased corrosivity will reduce pteropod habitat and likely lead to declines
Conclusions
Acknowledgements Samantha Zeman, Kym Jacobson, Cheryl Morgan, Jay Peterson, Leah Feinberg,
Tracy Shaw, Jennifer Menkel, Jesse F. Lamb, Toby Auth, Julie Keister, Aaron Chappell, Bobby Ireland, Thomas Murphy, Ryan Rykaczewski, Rian Hooff,
Ramiro Riquelmo, Jaime Gomez, Mitch Vance, Hui Lui
![Coastal-Change and Glaciological Map of the Larsen Ice Shelf … · 2009. 2. 19. · Larsen Ice Shelf ... and Palmer Land area (map I–2600–C)], was able to utilize the abundance](https://img.dokumen.tips/doc/110x75/60bab4d79050577b4507ab97/coastal-change-and-glaciological-map-of-the-larsen-ice-shelf-2009-2-19-larsen.jpg)
