Revising the Lower Trophic Level
Indicator
Presentation to the
Tidal Monitoring and Analysis Workgroup
June 12, 2012 Meeting
by
Jacqueline Johnson
Interstate Commission on the Potomac River
Basin
Components of the Habitats and
Lower Food Web Indicator
Phytoplankton
Wetlands
SAV
Benthos
Phytoplankton Reference Conditions
SEASON
Salinity
Regime
SPRING
Tidal Fresh
Oligohaline
Mesohaline
Polyhaline
SUMMER
Tidal Fresh
Oligohaline
Mesohaline
Polyhaline
Community
REFERENCE
DEGRADED
REFERENCE
DEGRADED
REFERENCE
DEGRADED
REFERENCE
DEGRADED
REFERENCE
DEGRADED
REFERENCE
DEGRADED
REFERENCE
DEGRADED
REFERENCE
DEGRADED
Secchi
Depth
>0.9
<=0.9
>0.7
<=0.7
>1.8
<=1.8
>2.15
<=2.15
>0.8
<=0.8
>0.6
<=0.6
>1.45
<=1.45
>1.85
<=1.85
PO4
NA
>0.007
NA
>0.007
NA
>0.007
NA
>0.007
NA
>0.007
NA
>0.007
<=0.007
>0.007
<=0.007
>0.007
DIN
NA
>0.070
NA
>0.070
NA
>0.070
NA
>0.070
NA
>0.070
NA
>0.070
<=0.070
>0.070
<=0.070
>0.070
Components of the PIBI
Habitat Class
Metric
BIOMASS_CHL_RATIO
CHLA_SURF
SPRING
SPRING
SPRING
SPRING
SUMMER
SUMMER
SUMMER
SUMMER
FRESH
OLIGOHALINE
MESOHALINE
POLYHALINE
FRESH
OLIGOHALINE
MESOHALINE
POLYHALINE
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
CRYPTO_BIO_PCT
CYANO_BIOMASS
X
DIATOM_BIOMASS
DINO_BIOMASS
DOC
MICROCYSTIS_AER_ABUND
PHEO
X
X
PICO_ABUND
PROROCENTRUM_MIN_ABUND
TOT_BIOMASS
1
2
3
4
5
X
X
X
X
X
X
X
X
X
X
X
Spring Index Performance
Base Period: 1984-2002
Recent Period: 2003-2010
Summer Index Performance
Base Period: 1984-2002
Recent Period: 2003-2010
Current PIBI Indicator
MRAT
Tributary PIBI Sample Count
45
40
35
30
25
20
15
10
5
0
1996
1997
1998
1999
2000
2001
2002
2003
2004
2005
2006
2007
2008
2009
CHOPTANK
PATAPSCO
PATUXENT
POTOMAC
RAPPAHANNOCK
YORK
ELIZABETH
JAMES
UPPER EAST
LOWER WEST
2010
2011
Mainstem PIBI Sample Counts
45
40
35
30
25
20
15
10
5
0
1996
1997
1998
1999
2000
2001
2002
UPPER BAY
2003
2004
MIDDLE BAY
2005
2006
2007
LOWER BAY
2008
2009
2010
2011
Choptank
Patapsco
Patuxent
Potomac
Lower West
Upper East
2011
2010
2009
2008
2007
2006
2005
2004
2003
2002
2001
2000
1999
1998
1997
1996
1995
1994
1993
1992
1991
1990
1989
1988
1987
1986
1985
Maryland Tributaries
100%
90%
80%
70%
60%
50%
40%
30%
20%
10%
0%
Patapsco River
5
10,000
4.5
3.5
1,000
PIBI SCORE
3
2.5
2
100
1.5
1
0.5
0
3/1/2011
4/1/2011
5/1/2011
6/1/2011
WT5.1
7/1/2011
flow
8/1/2011
9/1/2011
10
10/1/2011
Average Daily Stream Flow (CFS)
4
Potomac River
5
1,000,000
4.5
4
3.5
PIBI SCORE
3
2.5
10,000
2
1.5
1,000
1
0.5
0
3/1/2011
4/1/2011
5/1/2011
6/1/2011
TF2_3
7/1/2011
RET2_2
LE2_2
8/1/2011
flow
9/1/2011
100
10/1/2011
AVERAGE DAILY RIVER FLOW (CFS)
100,000
Issues and Options
• Due to reductions in sampling frequency the
annual mean PIBI score is more likely to
misrepresent a segment or a year with extreme
flow events .
– should we change the reporting window from 1 to 2
or more years?
– Should reporting be limited to areas with more than
one station
– What should be the minimum number of sampling
events for an area weighting analysis.
Discussion