apms 2005, san antonio, texas production and growth rates of egeria densa in the sacramento-san...
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APMS 2005, San Antonio, Texas
Production and growth rates of Production and growth rates of Egeria densaEgeria densa in in the Sacramento-San Joaquin Delta, Californiathe Sacramento-San Joaquin Delta, California
Toni G. PenningtonToni G. Pennington&&
Mark D. SytsmaMark D. SytsmaCenter for Lakes & ReservoirsCenter for Lakes & Reservoirs
Portland State UniversityPortland State UniversityPortland, OregonPortland, Oregon
APMS 2005, San Antonio, Texas
Models of growth & Models of growth & productionproduction
• Important to know conditions that favor/limit growth of Important to know conditions that favor/limit growth of nuisance aquatic plants under variable climates nuisance aquatic plants under variable climates Light availability, temperature, nutrients, water velocity, Light availability, temperature, nutrients, water velocity,
alkalinityalkalinity• Better inform management decisionsBetter inform management decisions
Herbicide application time, herbivore requirementsHerbicide application time, herbivore requirements• To predict effects of changing plant assemblages on water To predict effects of changing plant assemblages on water
quality and vice versaquality and vice versa Restoration, changes in turbidityRestoration, changes in turbidity
APMS 2005, San Antonio, Texas
Egeria densaEgeria densa (Brazilian elodea)(Brazilian elodea)
• Submersed macrophyte Submersed macrophyte • DioeciousDioecious• Reproduces by fragmentationReproduces by fragmentation• Introduced through aquarium tradeIntroduced through aquarium trade• Widely naturalized (Japan, New Zealand, Australia, Widely naturalized (Japan, New Zealand, Australia,
Denmark, Germany, France, Chile) Denmark, Germany, France, Chile) • Impedes recreation & navigation Impedes recreation & navigation • Alters pH and temperatureAlters pH and temperature• Controlled by herbicides and mechanical meansControlled by herbicides and mechanical means
APMS 2005, San Antonio, Texas
E. densaE. densa distribution in US distribution in USw
ww
. pl
ant
s.us
da.g
ov
APMS 2005, San Antonio, Texas
www. ucce.ucdavis.edu
APMS 2005, San Antonio, Texas
PurposePurpose
• To describe seasonal phenological To describe seasonal phenological responses of responses of EgeriaEgeria growing in growing in Western waterways to improve Western waterways to improve management efforts management efforts
• Accomplished by determining Accomplished by determining seasonal changes in: seasonal changes in: – nitrogen allocation nitrogen allocation – rates of photosynthesis & growth rates of photosynthesis & growth
APMS 2005, San Antonio, Texas
HypothesesHypotheses
• Egeria Egeria exhibits changes in nitrogen allocation between plant exhibits changes in nitrogen allocation between plant parts and seasons parts and seasons
• There are seasonal differences in maximum photosynthetic There are seasonal differences in maximum photosynthetic rate, light saturation, and growth rates of rate, light saturation, and growth rates of EgeriaEgeria
APMS 2005, San Antonio, Texas
Methods & results overviewMethods & results overview
• Study siteStudy site• Seasonal nitrogen allocationSeasonal nitrogen allocation• Photosynthetic responsePhotosynthetic response
– Maximum photosynthetic Maximum photosynthetic rate (Pmax)rate (Pmax)
– Photosynthetic efficiencyPhotosynthetic efficiency– Light saturation levelsLight saturation levels
• Growth rateGrowth rate
APMS 2005, San Antonio, Texas
Methods - Methods - study sitestudy site
• Sacramento-San Joaquin Delta, Sacramento-San Joaquin Delta, CA (Disappointment Slough)CA (Disappointment Slough)– Upper San Francisco BayUpper San Francisco Bay– 700 mi. of channels and 700 mi. of channels and
sloughssloughs– California Bay-Delta California Bay-Delta
Restoration ProjectRestoration Project
Ray Sterner, John H
opkins Univ.
APMS 2005, San Antonio, Texas
Methods – nitrogen allocationMethods – nitrogen allocation
• Plants collected monthly Dec 2003 to June 2005Plants collected monthly Dec 2003 to June 2005• Separated into: Separated into:
– Tips (upper 3 cm)Tips (upper 3 cm)– Lower stems (1Lower stems (1stst 15 cm from root crown) 15 cm from root crown)– Root crownsRoot crowns– RootsRoots
• Dried at 70Dried at 70ººC and groundC and ground• Analyzed on CHN elemental analyzerAnalyzed on CHN elemental analyzer
APMS 2005, San Antonio, Texas
• In tips: highest in winter ( 5.5%) and lowest in late summer (3.5%)In tips: highest in winter ( 5.5%) and lowest in late summer (3.5%)• Lower stems: 2.7% Lower stems: 2.7% • Root crowns: 3.6% Root crowns: 3.6% • Roots: 2.7%Roots: 2.7%
Results - nitrogen allocation
1
2
3
4
5
6
O-0
3
N-0
3
D-0
3
J-04
F-0
4
M-0
4
A-0
4
M-0
4
J-04
J-04
A-0
4
S-0
4
O-0
4
N-0
4
D-0
4
J-05
F-0
5
M-0
5
A-0
5
M-0
5
J-05
J-05
% N
Tips
1
2
3
4
5
6
O-0
3
N-0
3
D-0
3
J-04
F-0
4
M-0
4
A-0
4
M-0
4
J-04
J-04
A-0
4
S-0
4
O-0
4
N-0
4
D-0
4
J-05
F-0
5
M-0
5
A-0
5
M-0
5
J-05
J-05
% N
Tips Lower stems
1
2
3
4
5
6
O-0
3
N-0
3
D-0
3
J-04
F-0
4
M-0
4
A-0
4
M-0
4
J-04
J-04
A-0
4
S-0
4
O-0
4
N-0
4
D-0
4
J-05
F-0
5
M-0
5
A-0
5
M-0
5
J-05
J-05
% N
Tips Lower stems Root crowns
1
2
3
4
5
6
O-0
3
N-0
3
D-0
3
J-04
F-0
4
M-0
4
A-0
4
M-0
4
J-04
J-04
A-0
4
S-0
4
O-0
4
N-0
4
D-0
4
J-05
F-0
5
M-0
5
A-0
5
M-0
5
J-05
J-05
% N
Tips Lower stems Root crowns Roots
APMS 2005, San Antonio, Texas
Methods – production rateMethods – production rate
• Monthly from Dec 2003 to June 2005 bet. 10 am and 2 pmMonthly from Dec 2003 to June 2005 bet. 10 am and 2 pm• Incubated 15 cm tips in 300 ml BOD bottles in shipboard Incubated 15 cm tips in 300 ml BOD bottles in shipboard
circulating water bathcirculating water bath• Five light levels: 0 to 100% of surface irradianceFive light levels: 0 to 100% of surface irradiance• Measured DO, pH, and DIC to model Measured DO, pH, and DIC to model Pmax, photosynthetic Pmax, photosynthetic
efficiency and light saturationefficiency and light saturation
APMS 2005, San Antonio, Texas
Photosynthesis versus Irradiance (P vs I) curvesPhotosynthesis versus Irradiance (P vs I) curvesMichaelis – MentenMichaelis – Menten
P = P = (Pmax * I)(Pmax * I)
Ik + IIk + I
Pmax
Photosynthetic efficiency
Light saturation (I sat)
APMS 2005, San Antonio, Texas
• Same PmaxSame Pmax• Different saturationDifferent saturation
APMS 2005, San Antonio, Texas
Results – production ratesResults – production rates
• For some months, maximum production rates were For some months, maximum production rates were not achievednot achieved
• Why? Low ambient lightWhy? Low ambient light
APMS 2005, San Antonio, Texas
Results – Results – Photosynthetic Photosynthetic
efficiencyefficiency
(-) surface irradiance (+) %N in upper stems(-) surface irradiance (+) %N in upper stems
y = -1E-05x + 0.0339
r2 = 0.61p = 0.0001
0
0.01
0.02
0.03
0.04
0.05
0 1000 2000 3000Surface irradiance
Ph
oto
sy
nth
eti
c e
ffic
ien
cy
y = 0.0126x - 0.0282
r2 = 0.32p = 0.018
0
0.01
0.02
0.03
0.04
0.05
0.06
2.5 3.5 4.5%N Upper stems
Ph
oto
sy
nth
eti
c e
ffic
ien
cy
APMS 2005, San Antonio, Texas
Results – monthly PmaxResults – monthly Pmax
• Where maximum photosynthetic rate was observed, model Where maximum photosynthetic rate was observed, model and observed mean Pmax in close agreementand observed mean Pmax in close agreement
• Positive but weak relationship between Pmax and Positive but weak relationship between Pmax and temperature (p = 0.06)temperature (p = 0.06)
0
2
4
6
8
10
12
D-0
3
J-04
F-0
4
M-0
4
A-0
4
M-0
4
J-04
J-04
A-0
4
S-0
4
O-0
4
N-0
4
D-0
4
J-05
F-0
5
M-0
5
A-0
5
M-0
5
J-05
Pm
ax
(m
g O
2/m
g D
W/h
)
Observed Mean Pmax
Modelled Pmaxy = 0.1526x + 2.2253
r2 = 0.25p = 0.06
0
2
4
6
8
10
8 12 16 20 24Temperature (C)
Pm
ax
APMS 2005, San Antonio, Texas
Results - light saturationResults - light saturation
• Light saturation for Light saturation for EgeriaEgeria ranged from 130 to 690 ranged from 130 to 690 µµE mE m-2-2 s s-1-1 and and averaged 400 averaged 400 µµE mE m-2-2 s s-1-1
• Low saturation levels positively associated with increased N contentLow saturation levels positively associated with increased N content
SpeciesSpecies Collection site Collection site (Temp C)(Temp C)
Saturation Saturation ((µµE mE m-2-2 s s-1-1))
ReferenceReference
V. americanaV. americana WI lake (25)WI lake (25) 140140 Titus & Adams 1979Titus & Adams 1979
E. densaE. densa CA Delta (8-25)CA Delta (8-25) 400400 Present studyPresent study
M. spicatumM. spicatum FL lakes (30)FL lakes (30) 600600 Van et al. 1976Van et al. 1976
H. verticillataH. verticillata FL lakes (30)FL lakes (30) 600600 Van et al. 1976Van et al. 1976
C. demersumC. demersum FL lakes (30)FL lakes (30) 700700 Van et al. 1976Van et al. 1976
APMS 2005, San Antonio, Texas
Methods – seasonal Methods – seasonal growth rategrowth rate
• ~20 plants tagged on six occasions ~20 plants tagged on six occasions • Measured for tip, stem and Measured for tip, stem and
branch/bud growthbranch/bud growth• Potted in Delta sediment and allowed Potted in Delta sediment and allowed
to grow ~ three weeks in situto grow ~ three weeks in situ
APMS 2005, San Antonio, Texas
Results – growth Results – growth ratesrates
• Tips: 0.2 to 0.7 cm Tips: 0.2 to 0.7 cm .. d d-1-1
• Stems: 0.02 to 0.3 cm Stems: 0.02 to 0.3 cm .. d d-1-1
• Branch/bud: 0.03 to 0.8 cm Branch/bud: 0.03 to 0.8 cm .. d d-1-1
• Cumulative: 1 cm dCumulative: 1 cm d-1-1 April 2005 April 2005
AA
B
AAA
0
0.2
0.4
0.6
0.8
1
Nov-03 Dec-03 Apr-04 Aug-04 Nov-04 Apr-05
Gro
wth
(c
m/d
)
Tip
A AA
B
AA
A
B
AB A
B
0
0.2
0.4
0.6
0.8
1
Nov-03 Dec-03 Apr-04 Aug-04 Nov-04 Apr-05
Gro
wth
(c
m/d
)
Tip Stem
A AA
B
AA
A
B
AB A
B
A
A
A
0
0.2
0.4
0.6
0.8
1
Nov-03 Dec-03 Apr-04 Aug-04 Nov-04 Apr-05
Gro
wth
(c
m/d
)
Tip Stem Branch/bud
APMS 2005, San Antonio, Texas
ConclusionsConclusions
• Maximum nitrogen content observed in tips during the winter Maximum nitrogen content observed in tips during the winter and least in roots compared to all plant partsand least in roots compared to all plant parts
• Nitrogen content positively associated with photosynthetic Nitrogen content positively associated with photosynthetic efficiency and negatively associated with light saturation efficiency and negatively associated with light saturation
– i.e. more nitrogen = more efficient with less lighti.e. more nitrogen = more efficient with less light
• Maximum photosynthetic rates occurred during the summer, Maximum photosynthetic rates occurred during the summer, however that relationship to temperature was weakhowever that relationship to temperature was weak
• Maximum growth rate occurred during in April and growth Maximum growth rate occurred during in April and growth continued through the wintercontinued through the winter
APMS 2005, San Antonio, Texas
SummarySummary
• EgeriaEgeria under ideal temperature under ideal temperature conditions in the Deltaconditions in the Delta
• No “winter-type” growth form as No “winter-type” growth form as observed in S. Carolina and Japanobserved in S. Carolina and Japan
• Rapid spring growth suggests early Rapid spring growth suggests early season systemic herbicide application season systemic herbicide application
• Capable of adapting to low lightCapable of adapting to low light
Reduced photosynthetic efficiency with increased lightReduced photosynthetic efficiency with increased light
Low light saturation levels during the winterLow light saturation levels during the winter
APMS 2005, San Antonio, Texas
AcknowledgementsAcknowledgements
California Bay-Delta AuthorityCalifornia Bay-Delta Authority
USDA-APHISUSDA-APHIS
Perry Lake ManagementPerry Lake Management
Aquatic Ecosystem Aquatic Ecosystem Restoration FoundationRestoration Foundation
Staff & Students at the Center Staff & Students at the Center for Lakes & Reservoirsfor Lakes & Reservoirs
San Marcos River, Texas 1998