What we know about ecological response in Narragansett Bay from sediment studies

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What we know about ecological response in
Narragansett Bay from sediment studies
Sea Grant Nutrient Symposium Block Island 11/18/04

• John King - Kathryn Ford - Carol Gibson
• URI-Graduate School of Oceanography
• Paleomagnetics and Environmental Chemistry Lab
• Mark Cantwell - Richard McKinney
• EPA
• Atlantic Ecology Division

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BACKGROUND

• Surface sediment (0-2 cm)
• Recent contaminant inputs (1-10 years)
• Recent trends in productivity
• Spatial variability/trends down bay
• Core sediment (5 meters)
• History of contaminant input
• Alteration of carbon nitrogen inputs
• Community/productivity shifts over time

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Change Over Time Population Impact

• Conclusions
• C/N shift is linked to copper increasesanthropog
  enic source
• Fields Point precedes Sabin Point?

Nixon, 2004
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Change Over Time Nutrient Impact?

• Conclusions
• Increases in TOC, TN correspond to increases in
  Cu anthropogenic influence
• C/N less variability now than in past because
  of more constant nutrient influx?
• Very stable d15N no community change? Same
  source of nitrogen, just greater quantities?

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Down River Trends d15 N
FOX POINT
CONIMICUT POINT
Average 4.47o/oo
Average 7.18o/oo
Average 8.32o/oo
Average 7.72o/oo

• Conclusions
• Increasing values down river simply a shift to
  more marine community?
• Up river cores have increasing values can this
  be linked to anthropogenic or natural changes?

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Potential

• Defining baseline
• Indicator studies diatom, foram, seed, pollen,
  bacteria, fossil pigments anoxia
• Isotope tracing (metals, nutrients)
• Down bay trends metals, organics, nutrients
  sediment trap studies
• Linkage to water quality data unique
  opportunity!