Prof Christopher Gobler of Stony Brook University, a global expert on algal blooms and their causes, presents his overview of Long Island's nitrogen pollution problem and how that is triggering destructive algal blooms throughout our bays. The main culprit? 500,000 septic tanks.

1. Nitrogen Driven Degradation of
Long Island Water Bodies
Christopher J. Gobler, Ph.D.
Stony Brook University, School of Marine and Atmospheric Sciences

2. “Nitrogen is the critical limiting factor to
algal growth in Long Island coastal
marine waters”
– Dr. John Ryther, Woods Hole Oceanographic Institute,
Science Magazine, 1971

3. Population, Suffolk County, NY, USA
>25,000,000 lbs of nitrogen per year from human waste
1,600,000
Population
1,400,000
1,200,000
1,000,000
800,000
New
York
City
600,000
400,000
200,000
0
1900 1910 1920 1930 1940 1950 1960 1970 1980 1990 2000 2010

4. Long Island Legacy:
Household wastewater
In Suffolk County, 70% of
homes have septic tanks or
cesspools.
Septic tank
In eastern Suffolk
County, more than 90% of
homes have septic tanks or
cesspools.
Nitrogen
Water table
/ aquifer
Groundwater
flow
Nitrogen

5. 18 year change in groundwater nitrogen levels
40%
increase
Nitrogen content (mg/L)
4
Glacial
Magothy
200%
increase
3
2
1
0
1987
Suffolk County Comprehensive Water Resources management plan, 2010
2005

6. Rising nitrogen levels in our bays
Total Kjeldahl nitrogen (mg/L)
1.80
Great South Bay
1.60
1.60
Peconic Estuary
1.40
1.40
1.20
1.20
1.00
y = 2E-05x - 0.03
R² = 0.041
0.80
0.60
1.00
y = 3E-05x - 0.657
0.80
0.60
0.40
0.40
0.20
0.20
0.00
12/2/73 5/25/79 11/14/84 5/7/90 10/28/95 4/19/01
0.00
4/16/75
10/6/80
3/29/86
9/19/91
3/11/97

7. NYSDEC Impaired Water Bodies list
Samples for eelgrass genetic analyses
Hempstead Bay, Great South Bay, Moriches Bay, Quantuck
Bay, and Shinnecock Bay listed on the NYSDEC 303d list of
impaired water bodies due to “onsite waste disposal and
urban runoff”.
100 kilometers!
¼ of L.I. coast!

8. Nitrogen budget for Great South Bay
Fertilizer
= 15%
Atmospheric
deposition
= 30%
Wastewater
=55%
Kinney and Valiela, 2011
•~70% of N entering Moriches and Shinnecock Bay is from
wastewater (Gobler et al, in progress for NYSDOS).

9. Peconic nitrogen loading budgets

10. What impairments are brought about by
excessive nitrogen loading?
•
•
•
•
•
•
Loss of critical habitats: Eelgrass, salt marshes
Low dissolved oxygen levels, hypoxia
Acidification, low pH
Macroalgal blooms: Sea lettuce, Ulva
Toxic algal blooms: Red tides, brown tides
Loss or depletion of shellfisheries and finfisheries

11. Nitrogen impacts on salt marshes
• Salt marshes are critical habitats for protecting land, filtering
terrestrial pollutants, migratory birds, and marine life on Long Island.
• Nitrogen is accelerating the disappearance of salt marshes across
Long Island.

12. Salt
marshes
protect
bayside
properties
from wave
energy

13. Nitrogen loading as a driver of salt marsh loss on Long
Island, Deegan et al 2012, Nature
CAT scans of marsh roots
Collapsing salt marsh
Western Bays, Nassau County

14. Eelgrass: Critical
benthic habitat

15. Eelgrass: Critical
benthic habitat

16. Nitrogen impacts on seagrasses
• Eelgrass are critical habitats
for marine life on Long Island.
• Nitrogen is accelerating the
disappearance of eelgrass
across Long Island.

17. Impacts of nitrogen loading on seagrass

18. Effect of nitrogen load on eelgrass
growth, Peconic Estuary
120
Leaf mass (mg / SS)
100
80
60
40
20
0
0
230
480
Nitrogen loading (µM)
Rodgers 2010; Rodgers, Peterson, Gobler, in prep
700

19. Regional view of nitrogen pollution index of salt marshes
Dr. Fred Short, UNH
Long Island eelgrass beds
show multiple signs of
degradation due to
enrichment with sewagederived nitrogen.

20. Low (no) oxygen -another consequence of
excessive nitrogen loading (Hewlett Bay)
Dissolved Oxygen, mg L⁻¹
12
10
8
6
4
2
0
Bottom
NYS acute standard

21. Samples for eelgrass genetic analyses
Harmful algal blooms across Long Island
Cochlodinium
PSP
Toxic cyanobacteria
PSP
DSP
PSP, DSP
Ulva
Toxic cyanos
Cochlodinium
Cochlodinium
PSP
PSP,
DSP
PSP
Ulva
Ulva
Brown tide
DSP
Toxic cyanos
Cochlodinium

23. Alexandrium red tides and paralytic shellfish
poisoning (PSP)
Alexandrium
Saxitoxin

24. Saxitoxin producing Alexandrium
fundyense in NY waters
= cells not detected
= < 100 cells L-1
= 100 - 1,000 cells L-1
= > 1,000 cells L-1

25. Northport-Huntington Bay
PSP-shellfish
bed closures
across Long
Island since
2006

26. Expansion of PSP-induced shellfish bed
closures on Long Island, 2005 – 2012
Prior to 2006, Long Island had never experienced a PSP event
Acres of shellfish beds closed by
PSP
14000
12000
10000
8000
6000
4000
2000
0
2005
2006
2007
2008
2009
2010
Northport Bay
Northport and Huntington Bay
2011
2012
Northport, Huntington, and
Shinnecock Bay, Mattituck
Inlet and Sag Harbor Cove
Northport, Huntington, and Shinnecock Bay

27. Wastewater-derived nitrogen is
promoting the intensity and toxicity
of Alexandrium blooms.
Waste
water
N

28. Samples for eelgrass genetic analyses
Enhanced nutrient loading
Gobler et al
2012
Cochlodinium
Wallace
and
Gobler, sub
mitted
Ulva
more intense &/or toxic HABs
Hattenrath
et al 2010
Alexandrium
Hattenrath et al
in prep
Dinophysis
Gobler et al
2011,
Gobler and
Sunda 2012
Brown tide

29. Nitrogen impacts on shellfish
• Landings of clams and scallops have declined 99% since 1980.
• Linkages to nitrogen driven HABs, habitat loss, and water quality
degradation.
Hard clam landings (bushels) in Great South Bay
800,000
700,000
600,000
500,000
400,000
300,000
200,000
100,000
2006
2004
2002
2000
1998
1996
1994
1992
1990
1988
1986
1984
1982
1980
1978
1976
1974
1972
1970
0

30. What impairments are brought about by
excessive nitrogen loading?
•
•
•
•
•
•
Loss of critical habitats: Eelgrass, salt marshes
Low dissolved oxygen levels, hypoxia
Acidification, low pH.
Macroalgal blooms: Sea lettuce, Ulva
Toxic algal blooms: Red tides, brown tides
Loss or depletion of shellfisheries and finfisheries