Western Washington University
Western CEDAR
Salish Sea Ecosystem Conference
2014 Salish Sea Ecosystem Conference (Seattle)
Apr 30th, 10:30 AM - 12:00 PM
Can long term-nitrogen increases affect pelagic
food web processes and the vertical structure of
biogeochemical processes in Puget Sound?
Christopher Krembs
Washington (State). Department of Ecology, [email protected]
Skip Albertson
Washington (State). Department of Ecology
Julia Bos
Carol Maloy
Washington (State). Department of Ecology
Mya Keyzers
Washington (State). Department of Ecology
See next page for additional authors
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Part of the Terrestrial and Aquatic Ecology Commons
Krembs, Christopher; Albertson, Skip; Bos, Julia; Maloy, Carol; Keyzers, Mya; Sackmann, Brandon; Hermanson, Laura; and Dutch,
Maggie, "Can long term-nitrogen increases affect pelagic food web processes and the vertical structure of biogeochemical processes in
Puget Sound?" (2014). Salish Sea Ecosystem Conference. 19.
http://cedar.wwu.edu/ssec/2014ssec/Day1/19
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Presenter/Author Information
Christopher Krembs, Skip Albertson, Julia Bos, Carol Maloy, Mya Keyzers, Brandon Sackmann, Laura
Hermanson, and Maggie Dutch
This is available at Western CEDAR: http://cedar.wwu.edu/ssec/2014ssec/Day1/19
Can long term-nitrogen increases affect pelagic food web processes and
the vertical structure of biogeochemical processes in Puget Sound?
Christopher Krembs, Maggie Dutch, Julia Bos, Skip Albertson, Brandon Sackmann, Mya Keyzers, Laura Friedenberg, Carol Maloy
1.
Nitrate concentrations are increasing.
Large flagellate blooms occur near the surface
2.
Phytoplankton biomass is declining!
3.
Large Noctiluca blooms
Micro-zooplankton grazing (200µM) is important!
HS: Are energy and material cycling through the
lower pelagic food web changing?
Benthic species match observations in the water
Lower food web dynamics remain a knowledge gap in Puget Sound, yet is
indispensable to connect water quality to the marine food web.
Nitrate inter-annual
anomalies
( µM, 0-30m)
Change in
nitrate
Nitrate concentrations are increasing (non-oceanic cause)
Marine long-term
monitoring locations in
the greater Puget Sound
area (southern Salish Sea).
2.5
y = 0.2007x - 402.49
R² = 0.4003
2.0
1.5
1.0
0.5
0.0
-0.5
-1.0
-1.5
-2.0
-2.5
1998 2000 2002 2004 2006 2008 2010 2012 2014
Puget Sound Stations
Anomalies in nitrate
Red dots
monthly-visited
water-column
stations.
Si:N nutrient ratio is falling (eutrophication indicator)
Lower Si:N ratios can favor
non-silicified phytoplankton taxa
Large and abundant flagellate blooms
at the water surface
Si:N inter-annual anomalies (0-30m)
25
20
y = -0.9223x + 1855.4
R² = 0.3423
15
10
5
0
-5
-10
1998 2000 2002 2004 2006 2008 2010 2012 2014
Case Inlet, South Puget Sound 2011
Time ( years)
Nitrogen increases are driving the decline in the Si:DIN ratio!
Chlorophyll inter-annual anomalies (mg Chl a m-2,0-50m)
Phytoplankton biomass: a 14-year decline (0-50m)
100
y = -5.5987x + 11251
R² = 0.5312
80
60
40
20
0
-20
-40
1998
2000
2002
2004
2006
2008
2010
2012
2014
The Puget Sound-wide decline in phytoplankton biomass relative to baseline
conditions (1999-2008) does not follow the pattern of a bottom-up nutrient control.
Inter-annual variability in phytoplankton biomass
could explain changes in macro-nutrients?
Chlorophyll a inter-annual
anomalies
(mg
Chlm-2)
a m-2, 0-50m)
Chl a anomalies
(micro
gram
Nitrate and Chl a
100
Micro-zooplankton (<200 µm)
y = -19.507x + 20.642
R² = 0.6486
80
Micro-zooplankton grazers can remove
the entire diatom standing stock
each day!
60
40
(e.g., Verity et al., 1996a; Suzuki et al., 2002)
20
Balance between microzooplankton
grazing and phytoplankton growth in
Dabob Bay (Hood Canal)…
0
-20
Spearman Rank Corr. Coef. p=<0.05
-40
-3
-2
-1
0
1
2
3
Leising et al., 2005. The balance between microzooplankton
grazing and phytoplankton growth in a highly productive
estuarine fjord. Progress in Oceanography 67:366–383.
Nitrate
anomalies (micro
Nitrate
anomalies
(µM,Molar)
0-30m)
What controls phytoplankton inter-annual variability
could also control nutrients in Puget Sound surface water?
Noctiluca blooms are large (eutrophication indicator)
A strong competitor to copepods that feed on diatoms!
Food : No food preference! (Diatoms, flagellates, detritus, nauplii, copepod and fish eggs…)
sail boat
Note:
Blooms of Noctiluca are
linked to massive fish and
invertebrate kills.
(Okaichi & Nishio ,1976; Fukuyo et al., 1990)
Noctiluca rapidly recycles sinking fecal pellets and retains nutrients in the surface.
(Kiørboe, Thomas 2003)
Noctiluca blooms are large (eutrophication indicator)
A strong competitor to copepods that feed on diatoms!
Food : No food preference! (Diatoms, flagellates, detritus, nauplii, copepod and fish eggs…)
sail boat
Some juvenile salmons peak in June in PS
King County 2004, Juvenile salmon composition, timing, distribution and diet in
marine nearshore waters of central Puget Sound in 2001-2002
Note:
Blooms of Noctiluca are
linked to massive fish and
invertebrate kills.
(Okaichi & Nishio, 1976; Fukuyo et al., 1990)
Noctiluca rapidly recycles sinking fecal pellets and retains nutrients in the surface.
(Kiørboe, Thomas 2003)
Grazing is reflected in the seasonality of
Phytoplankton biomass and NH4 in Puget Sound
250
2.5
200
2.0
150
1.5
100
1.0
Noctiluca blooms
50
0.5
2011
2012
2013
0
1
2
3
4
5
6
7
Month
0.0
8
9
10
11
12
Ammonium conc. (µM l-1)
Chlorophyll content 0-50m (mg Chl a m-2)
10-year median, Puget Sound
Grazing is reflected in the seasonality of
Phytoplankton biomass and NH4 in Puget Sound
250
2.5
200
2.0
X
150
1.5
100
1.0
Noctiluca blooms
50
0.5
2011
2012
2013
0
1
2
3
4
5
6
7
Month
0.0
8
9
10
11
12
Ammonium conc. (µM l-1)
Chlorophyll content 0-50m (mg Chl a m-2)
10-year median, Puget Sound
Chl a summer peak looses its strength.
Question: Top-down control or abiotic factors?
Puget Sound wide avg. Chl a (mg Chl a m-2)
Note:
NH4 max also decreases in late summer; average is unchanged
Spring Max
Summer Max
Yearly AVG
500
400
y = -15.896x + 32153
R² = 0.4633
300
200
100
y = -6.9338x + 14045
R² = 0.58
0
1999
2001
2003
2005
2007
2009
2011
2013
Surface material eventually sinks to the bottom and feeds the
benthos. Why micro-zooplankton grazers do matter!
copepods
micro-grazers
e.g. Noctiluca
Ecology’s Marine Sediment Monitoring Program
Remineralization
Fast-sinking nutrient-rich
fecal pellets
Slow-sinking nutrientpoor loose aggregates
Are micro-grazers changing the organic particle export
to the benthos (the benthic-pelagic coupling)?
Marine long-term monitoring locations in the
greater Puget Sound area (southern Salish Sea).
Colored regions benthic monitoring regions.
Could micro-grazers change particles from fast-sinking nutrient-rich fecal
pellets to slow-sinking nutrient-poor loose aggregates?
Decadal decline in benthic abundance and taxa richness
Wednesday 4:15 PM
S-3A Changes in Salish
Sea water quality
Room: 615/616/617
Partridge, V.
Characterizing changes
in Puget Sound benthic
infaunal invertebrate
assemblages: A
functional approach
Are these signs of a reduced particle export to the benthos?
Hypothesis for combining a series of recent observations
affecting energy transfer to higher trophic levels
Increases in
nitrate conc. in
PS could be
caused by a topdown control on
phytoplankton
biomass.
Si:N
Is Noctiluca
a harbinger of a
food web
shift towards
increased microzooplankton
grazing?
POSTER:
Krembs, C. Changes in nutrient ratios drive changes in pelagic and benthic assemblages, and
benthic-pelagic coupling in Puget Sound: A compelling hypothesis linking water quality and
the benthos.