Habitat Indicators Primary Production Winter Spring Diatom Bloom Summer Hypoxia and Fish Biomass Candace Oviatt Heather Stoffel Laura Reed Edwin Requintina Graduate School of Oceanography URI ID: 605857
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Slide1
The Bay After Nutrient Reduction
Habitat Indicators: Primary Production, Winter Spring Diatom Bloom, Summer Hypoxia and Fish Biomass
Candace
Oviatt
,
Heather
Stoffel
, Laura Reed, Edwin
Requintina
Graduate School of Oceanography, URI
CHRP Presentation – Coastal Institute
Hazzard
Rooms
May 19, 2016Slide2
Improvements in the Bay due to the Clean Water Act of 1972
and Amendments of 1977, 1987
1988 Used Oil Recycling Program
Heavy Metal Recycling Program
Millions of gallons of used oil collected and recycled.
Heavy metals at low background concentrations during 2001
Providence River Survey.
1993- Combined Sewer Over-Flow Abatement Program
Phase I and 2 completed in 2008 and 2014.
Reduced bacterial contamination of Bay beaches and new shell-fishing
grounds opened.
2005- 30% Reduction in
Standing Stock nitrogen concentrations in the
Bay
2013 50% Reduction in
Standing Stock nitrogen
concentrations
in the
BaySlide3
Summer Production 2013Slide4Slide5Slide6
Summer Surface System Apparent Production, g O
2 m-3 d-1Slide7
Winter-Spring Diatom Bloom 2014 in the Upper Bay (CP), Mid Bay (GB & TW) and Lower Bay (GSO
)Slide8
The Number of Summer Days of Hypoxia has Decreased.Slide9
Percent Reduction in
Hypoxia
from 2012 to 2013 - 2014
Phillipsdale
27
Bullock Reach
46
Conimicut Pt
19
North Prudence
43
Popposquash Pt
37
Greenwich Bay
32
Mt. View
32
T-Wharf
100
Quonset Pt
37
GSO Dock
100Slide10Slide11
Total Fish Biomass Before and After Nitrogen Reduction.Slide12
Conclusions
Managed DIN reduction has achieved about a 60% reduction.Primary Production in the Bay has declined
in mid Bay
by 31-45%.
The Winter-Spring Diatom Bloom has declined by over 50%.
Summer hypoxia has declined in the upper Bay by 30%.
Fish biomass in the Bay has increased particularly in upper Bay areas prone to hypoxia.
The fish biomass after the 50% nitrogen reduction has decreased but is still higher than the decade prior to nitrogen reduction. This trend bears watching.
Overall water quality in the Bay has improved.