Narragansett Bay time series: 1959 to 1997

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Narragansett Bay time series 1959 to 1997
Meteorological Nutrients River flow
1959-97 NO3 1959-63, 69-97 Precipitation 1959
-97 NH3 1972-97 Wind speed 1959-97 PO4 1959
-63, 69-97 Irradiance 1959-97 SiO3 1959-63,
69-97 Temperature 1959-97 Urea 1972-78 Salin
ity 1959-97 NO3 reductase 1975-77 Secchi
depth 1972-97 PO4 reductase 1976-77 Phy
toplankton Zooplankton Species
composition 1959-97 Species composition 1972-90 A
bundance 1959-97 Numerical abundance 1972-90 Chl
orophyll 1968-69, 72-97 Dry wt .
biomass 1972-97 ATP-C biomass 1972-97 C, N
biomass 1972-97 Primary production 1979-90 Cten
ophore abundance 1973-97 Size fractionation 1972
-78, 87-88
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2
7
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Mean Annual PO4 (mM)
Mean Annual S (psu)
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Mean Annual Si(OH)4 (mM)
Mean Annual S (psu)
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Mean Annual Chlorophyll (mg m-3)
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Mean Annual S (psu)
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Mean Annual Chlorophyll (mg m-3)
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Mean Annual PO4 (mM)
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Mean Annual Carbon Production (g C m-3)
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Mean Annual S (psu)
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Annual Carbon Production (g C m-3 )
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Mean Annual NH4 NO3 (mM)
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Annual Carbon Production (g C m-3 y-1)
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Mean Annual PO4 (mM)
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Annual Carbon Production (g C m-3 )
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Mean Annual Si(OH)4 (mM)
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Mean Annual Zooplankton (mg dry wt m-2)
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Mean Annual salinity (psu)
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Mean Zooplankton Dry Weight (mg m-2)
Mean Annual Chlorophyll (mg m-3)
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GRADIENT ANALYSIS SUMMARY

• Gradients occur in
• Salinity, Nutrients, Phytoplankton (biomass,
  production), Zooplankton Ctenophore biomass
• Upper NBay exports nutrients, ctenophores downbay
• NBay Sanctuary region an important nutrient
  depuration zone
• Nutrient gradient pulsates with riverine
  discharge
• Uniform bloom behavior characterizes NBay
• Spatial shift from Si limitation in upper NBay to
  N limitation downbay
• Coupling occurs between
• Nutrients and salinity
• Chlorophyll and nutrients
• Primary production and nutrients
• Zooplankton - Phytoplankton Biomass
• Zooplankton - Phytoplankton Production

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Nitrogen
Monthly TSS Nitrogen Discharge (kg)
Phosphorus
Monthly TSS Phosphorus Discharge (kg)
Year
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Skeletonema potential from TSS Nitrogen
Skeletonema cells from TSS nitrogen
Year
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Chlorophyll potential from TSS Nitrogen
Estimated Chlorophyll from TSS Nitrogen (mg m-3)
Year
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r2 0.46 (all data) r2 0.75 (w/o 1983, 1996)
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4
3
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1955
1960
1965
1970
1975
1980
1985
1990
1995
2000
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NO3 (mM m-2)
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Mean Annual Diatom Flagellate Ratio
Year
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r2 0.69, plt0.0001
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r2 0.46, plt0.0005
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Narragansett Bay Skeletonema bloom timing,
magnitude and duration - NAOI effects
(cold)
(warm)
Bloom response (-) NAO Years () NAO Years p
value Annual maximum week 13 30 0.046 W-s
bloom duration (weeks) 9 4 0.025 Maximum w-s
abundance (cells ml-1) 24,967 1,713 0.009 1Q
mean abundance (cells ml-1) 5,536 399 0.016 2Q
mean abundance (cells ml-1) 2,578 166 0.009
weeks gt500 cells ml-1 0.43 0.23 0.028
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Mean Skeletonema costatum (cells ml-1)
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Cells ml-1
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Narragansett Bay Zooplankton - NAO Correlation
NAO annual 1Q NAOI 4Q NAOI
mean p value Annual mean Cladocerans 0.51
0.050 Annual mean Acartia
hudsonica 0.48 0.073 4Q Acartia
tonsa 0.58 0.57 0.027
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NBAY TIME SERIES SUMMARY

• Major changes, trends have occurred in
• Physical properties (temperature transparency)
• Macronutrients (concentrations ratios)
• Plankton
• Phytoplankton biomass, production bloom cycles,
  species
• Copepod abundance
• Plankton dynamics are regulated by two primary
  and confluent drivers
• Internal forcing (nutrient supply, ratios)
• External forcing (climate coastal shelf physics)
• Strong field evidence that plankton dynamics
  sensitive to nutrient and thermal conditions,
  consistent with transect and experimental data
• NBay a biogeographic transition zone this should
  be factored into studies evaluating responses to
  altered nutrient supply

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NBAY TIME SERIES SUMMARY

• Highly predictable open niche period sensitive
  to nutrients and grazers follows winter-spring
  bloom period, but
• Bloom species selection and grazer behavior
  unpredictable
• Aquaculture would become a relevant, new driver
• Functional group shifts have occurred
• Has a domain shift occurred?
• Essential that process-oriented monitoring at the
  Fox Island long-term station be resumed