Presentation is loading. Please wait.

Presentation is loading. Please wait.

APMS 2005, San Antonio, Texas Production and growth rates of Egeria densa in the Sacramento-San Joaquin Delta, California Toni G. Pennington & Mark D.

Similar presentations


Presentation on theme: "APMS 2005, San Antonio, Texas Production and growth rates of Egeria densa in the Sacramento-San Joaquin Delta, California Toni G. Pennington & Mark D."— Presentation transcript:

1 APMS 2005, San Antonio, Texas Production and growth rates of Egeria densa in the Sacramento-San Joaquin Delta, California Toni G. Pennington & Mark D. Sytsma Center for Lakes & Reservoirs Portland State University Portland, Oregon

2 APMS 2005, San Antonio, Texas Models of growth & production Important to know conditions that favor/limit growth of nuisance aquatic plants under variable climatesImportant to know conditions that favor/limit growth of nuisance aquatic plants under variable climates Light availability, temperature, nutrients, water velocity, alkalinity Light availability, temperature, nutrients, water velocity, alkalinity Better inform management decisionsBetter inform management decisions Herbicide application time, herbivore requirements Herbicide application time, herbivore requirements To predict effects of changing plant assemblages on water quality and vice versaTo predict effects of changing plant assemblages on water quality and vice versa Restoration, changes in turbidity Restoration, changes in turbidity

3 APMS 2005, San Antonio, Texas Egeria densa (Brazilian elodea) Submersed macrophyteSubmersed macrophyte DioeciousDioecious Reproduces by fragmentationReproduces by fragmentation Introduced through aquarium tradeIntroduced through aquarium trade Widely naturalized (Japan, New Zealand, Australia, Denmark, Germany, France, Chile)Widely naturalized (Japan, New Zealand, Australia, Denmark, Germany, France, Chile) Impedes recreation & navigationImpedes recreation & navigation Alters pH and temperatureAlters pH and temperature Controlled by herbicides and mechanical meansControlled by herbicides and mechanical means

4 APMS 2005, San Antonio, Texas E. densa distribution in US www. plants.usda.gov

5 APMS 2005, San Antonio, Texas www. ucce.ucdavis.edu

6 APMS 2005, San Antonio, TexasPurpose To describe seasonal phenological responses of Egeria growing in Western waterways to improve management effortsTo describe seasonal phenological responses of Egeria growing in Western waterways to improve management efforts Accomplished by determining seasonal changes in:Accomplished by determining seasonal changes in: –nitrogen allocation –rates of photosynthesis & growth

7 APMS 2005, San Antonio, TexasHypotheses Egeria exhibits changes in nitrogen allocation between plant parts and seasonsEgeria exhibits changes in nitrogen allocation between plant parts and seasons There are seasonal differences in maximum photosynthetic rate, light saturation, and growth rates of EgeriaThere are seasonal differences in maximum photosynthetic rate, light saturation, and growth rates of Egeria

8 APMS 2005, San Antonio, Texas Methods & results overview Study siteStudy site Seasonal nitrogen allocationSeasonal nitrogen allocation Photosynthetic responsePhotosynthetic response –Maximum photosynthetic rate (Pmax) –Photosynthetic efficiency –Light saturation levels Growth rateGrowth rate

9 APMS 2005, San Antonio, Texas Methods - study site Sacramento-San Joaquin Delta, CA (Disappointment Slough)Sacramento-San Joaquin Delta, CA (Disappointment Slough) –Upper San Francisco Bay –700 mi. of channels and sloughs –California Bay-Delta Restoration Project Ray Sterner, John Hopkins Univ.

10 APMS 2005, San Antonio, Texas Methods – 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) –Lower stems (1 st 15 cm from root crown) –Root crowns –Roots Dried at 70ºC and groundDried at 70ºC and ground Analyzed on CHN elemental analyzerAnalyzed on CHN elemental analyzer

11 APMS 2005, San Antonio, Texas In tips: highest in winter ( 5.5%) and lowest in late summer (3.5%) Lower stems: 2.7% Root crowns: 3.6% Roots: 2.7% Results - nitrogen allocation

12 APMS 2005, San Antonio, Texas Methods – 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 circulating water bathIncubated 15 cm tips in 300 ml BOD bottles in shipboard circulating 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 Pmax, photosynthetic efficiency and light saturationMeasured DO, pH, and DIC to model Pmax, photosynthetic efficiency and light saturation

13 APMS 2005, San Antonio, Texas Photosynthesis versus Irradiance (P vs I) curves Michaelis – Menten P = (Pmax * I) Ik + I Ik + I Pmax Photosynthetic efficiency Light saturation (I sat )

14 APMS 2005, San Antonio, Texas Same PmaxSame Pmax Different saturationDifferent saturation

15 APMS 2005, San Antonio, Texas Results – production rates For some months, maximum production rates were not achievedFor some months, maximum production rates were not achieved Why? Low ambient lightWhy? Low ambient light

16 APMS 2005, San Antonio, Texas Results – Photosynthetic efficiency (-) surface irradiance (+) %N in upper stems

17 APMS 2005, San Antonio, Texas Results – monthly Pmax Where maximum photosynthetic rate was observed, model and observed mean Pmax in close agreementWhere maximum photosynthetic rate was observed, model and observed mean Pmax in close agreement Positive but weak relationship between Pmax and temperature (p = 0.06)Positive but weak relationship between Pmax and temperature (p = 0.06)

18 APMS 2005, San Antonio, Texas Results - light saturation Light saturation for Egeria ranged from 130 to 690 µE m -2 s -1 and averaged 400 µE m -2 s -1Light saturation for Egeria ranged from 130 to 690 µE m -2 s -1 and averaged 400 µE m -2 s -1 Low saturation levels positively associated with increased N contentLow saturation levels positively associated with increased N content Species Collection site (Temp C) Saturation (µE m -2 s -1 ) Reference V. americana WI lake (25) 140 Titus & Adams 1979 E. densa CA Delta (8-25) 400 Present study M. spicatum FL lakes (30) 600 Van et al H. verticillata FL lakes (30) 600 Van et al C. demersum FL lakes (30) 700 Van et al. 1976

19 APMS 2005, San Antonio, Texas Methods – seasonal growth rate ~20 plants tagged on six occasions~20 plants tagged on six occasions Measured for tip, stem and branch/bud growthMeasured for tip, stem and branch/bud growth Potted in Delta sediment and allowed to grow ~ three weeks in situPotted in Delta sediment and allowed to grow ~ three weeks in situ

20 APMS 2005, San Antonio, Texas Results – growth rates Tips: 0.2 to 0.7 cm. d -1Tips: 0.2 to 0.7 cm. d -1 Stems: 0.02 to 0.3 cm. d -1Stems: 0.02 to 0.3 cm. d -1 Branch/bud: 0.03 to 0.8 cm. d -1Branch/bud: 0.03 to 0.8 cm. d -1 Cumulative: 1 cm d -1 April 2005Cumulative: 1 cm d -1 April 2005

21 APMS 2005, San Antonio, TexasConclusions Maximum nitrogen content observed in tips during the winter and least in roots compared to all plant partsMaximum nitrogen content observed in tips during the winter and least in roots compared to all plant parts Nitrogen content positively associated with photosynthetic efficiency and negatively associated with light saturationNitrogen content positively associated with photosynthetic efficiency and negatively associated with light saturation –i.e. more nitrogen = more efficient with less light Maximum photosynthetic rates occurred during the summer, however that relationship to temperature was weakMaximum photosynthetic rates occurred during the summer, however that relationship to temperature was weak Maximum growth rate occurred during in April and growth continued through the winterMaximum growth rate occurred during in April and growth continued through the winter

22 APMS 2005, San Antonio, TexasSummary Egeria under ideal temperature conditions in the DeltaEgeria under ideal temperature conditions in the Delta No winter-type growth form as observed in S. Carolina and JapanNo winter-type growth form as observed in S. Carolina and Japan Rapid spring growth suggests early season systemic herbicide applicationRapid spring growth suggests early season systemic herbicide application Capable of adapting to low light Reduced photosynthetic efficiency with increased light Low light saturation levels during the winter

23 APMS 2005, San Antonio, Texas Acknowledgements California Bay-Delta Authority USDA-APHIS USDA-APHIS Perry Lake Management Aquatic Ecosystem Restoration Foundation Staff & Students at the Center for Lakes & Reservoirs San Marcos River, Texas 1998


Download ppt "APMS 2005, San Antonio, Texas Production and growth rates of Egeria densa in the Sacramento-San Joaquin Delta, California Toni G. Pennington & Mark D."

Similar presentations


Ads by Google