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Nutrient and Ecological Histories in the Murderkill River

Nutrient and Ecological Histories in the Murderkill River. Drs. David Velinsky 1 , Christopher Sommerfield 2 , and Don Charles 1 1 The Academy of Natural Sciences Patrick Center for Environmental Research 2 University of Delaware, CMES Project update: 2 March 2010. Objectives.

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Nutrient and Ecological Histories in the Murderkill River

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  1. Nutrient and Ecological Histories in the Murderkill River Drs. DavidVelinsky1, Christopher Sommerfield2, and Don Charles1 1The Academy of Natural Sciences Patrick Center for Environmental Research 2University of Delaware, CMES Project update: 2 March 2010

  2. Objectives • Collect sediment cores from 3 marsh sites within the tidal • Murderkill River basin • Determine sediment accumulation rates using 210Pb and 137Cs geochronology • Analyze sediments for C, N, P and indicators of ecological • change (diatoms, stable isotopes, others) • Reconstruct history of ecological changes and environmental • management practices over time

  3. Coring sites

  4. Photos from the river

  5. Sediment physical properties

  6. Sediment physical properties

  7. Pb-210 & Cs-137 Pb-210 & Cs-137 Conceptual model of marsh accretion French (2006)

  8. Radionuclide profiles (MK 4B) 137Cs inventory = 9.2 dpm/cm2 137Cs accretion rate = 3.6 mm/yr 210Pb inventory = 55.4 dpm/cm2 210Pb accretion rate = 2.8 mm/yr • Observations • Evidence of Pb-210 influx from DE Bay • Evidence of Cs-137 desorption • Accretion rates typical for DE salt marshes

  9. Sediment age model

  10. Murderkill River: Coring sites Site 4 0.36 cm/yr Site 3 0.56 cm/yr 0.80 cm/yr Site 2 Site 1 0.80 cm/yr

  11. Delaware Estuary Sediment Core Sites Sites sampled from 2006-09 Sites sampled prior to 2006 Three cores were collected at each site in mid-marsh areas.

  12. Upper Bay Lower Bay Sediment Accretion Rates 0.72 ± 0.21 cm/yr (n=29) • Average (± 1s) =0.50 ± 0.4 cm/yr (n=32) • Max = 1.3 cm/yr • Min = 0.3 cm/yr Murderkill River Averages of multiple cores taken from one marsh system

  13. C to N reflects the differences between terrestrial versus marine sources of organic matter.. C/Nterrestrial = > 10 C/Nmarine ~ 6 to 8

  14. TBD TBD

  15. d13CSpartina ~ -12.5 to -13.6‰ (MRsp) d13C DE seston ~ -27 to -20‰ d13C terr ~ > -20‰ (lower bay)

  16. Analyze Data PaleolimnologicalApproach 210Pb 137Cs 14C Select Coring Site & Retrieve Sediment Cores Select Study Sites Section & Date Sediment Cores Sub-sample Sediments & Isolate Diatoms Identify and Count Diatoms

  17. Methods – Diatom species • 300-600 diatom valves counted; 50 – 90 taxa per sample • PCA – measure of main directions of variation of diatom assemblages • Trophic metrics – Van Dam • Cross-correlations – diatoms with sediment chemistry and climate records

  18. Diatom species – environmental gradient sp. 4 sp. 1 sp. 3 sp. 5 sp. 6 Abundance of taxa sp. 2 Low Nutrient >>>>>>>>>>> High Nutrient

  19. Murderkill Core 1 Planothidium frequentissimum Amphora sp. 1 MUR DME Navicula sp. 1 MUR DME Gyrosigma acuminatum Actynocyclus normanii Navicula digitoradiata Navicula tenelloides Amphora holsatica Tryblionella debilis Cymatosira belgica Fallacia pygmaea Denticula subtilis Cyclotella striata Cymbella pusilla Diploneis parma Paralia sulcata Navicula cincta Luticola mutica MURD0001 MURD0003 MURD0005 Depth MURD0006 MURD0007 MURD0009 MURD0011 MURD0013 MURD0015 MURD0021 MURD0029 % Relative abundance 0 20 0 0 0 0 0 0 0 0 0 0 0 0 20 0 0 0 20 0 20 40 0

  20. Christina R. – Churchman core - Relationships with sediment chemistry Sediment diatoms Sediment chemistry δ 15N eutroph mes-eut meso oligo PCA1 PCA2 TN δ13C PCBs Year 2000 1980 1960 1940 1920 1900 1880 0.1 0.4 0.8 -2 0 2 -28 -26 1860 4 6 8 20 60 2 6 10 0 2 4 0 2 -2 0 2 0 2000 Van Dam Index PCA Scores % permil permil ng/g

  21. In Progress • Done: Radionuclide measurements for 4 cores • Finish last 2 cores: Total P • Finish 2.5 cores: Diatom identification • Summary Report and QA: April 2010 • Sediment Accumulation (OM, IM, C, N, and P) • CNP changes with time • Ecological changes with diatoms

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