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Submerged aquatic vegetation (SAV) abundance and diversity in the tidal Potomac River and estuary
By Nancy Rybicki, Jurate Landwehr, Edward Schenk, and Julie Baldizar
Goal: provide managers with information to help them understand variation in SAV coverage and determine strategies to meet the SAV restoration goal.
Tidal Fresh SAV
0
1000
2000
3000
78 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 00 01 02 03 04
Years
SAV restoration goal based on historical coverage (1930's and 1950's)
Variation in SAV coverage, Potomac RiverSAV data from http://www.vims.edu/bio/sav :
Oligohaline SAV
0
5001000
1500
2000
78 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 00 01 02 03 04
Years
SA
V (
Hec
tare
s)
SAV restoration goal based on historical coverage (1930's and 1950's)
Mesohaline Potomac SAV
01000200030004000
1978
1983
1984
1985
1986
1987
1988
1989
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004
SAV restoration goal based on historical coverage (1930's and 1950's)
No
data
River Flow
Phyto-plankton
Nutrients
Water Temperature
Total SuspendedSolids
Epiphytes
Solar radiation
Submersed Aquatic Vegetation
Light
Wind Speed
Water clarity is the primary factors influencing SAV abundance.
Literature review and analyses indicated MLRs of13% light for the fresh and oligohaline and22% for mesohaline to polyhaline SAV community (Carter et al. 2000, Batiuk et al. 2000, Kemp, et al. 2004)
Secchi depth of 0.7m = 13% light at 1m
1) EVALUATION OF SUBMERGED AQUATIC VEGETATION (SAV) AND WATERFOWL POPULATIONS WITH RESPECT TO EXOTIC SPECIES AND IMPROVING WATER QUALITY
2) POSSIBLE CAUSE OF VIRGINIA TRANSPLANTS 2003 & 2004
3) MAP SHOWING POTENTIAL AND CONTINUEING USGS WORK
Study Area
Improved water quality in an estuary with exotics enhances SAV diversity and waterfowl habitat,
by Rybicki and Landwehr
Data source:
SAV species, USGS and DC gov’t
SAV coverage, VIMS
Water quality, MDDNR
Waterfowl, Audobon Christmas bird count
Rybicki and Landwehr, in process
UTR
0
200
400
600
800
1000
1200
1400
1985
1987
1989
1991
1993
1995
1997
1999
2001
Other exotic Hydrilla
Native No species data
UOE
0
200
400
600
800
1000
1985
1987
1989
1991
1993
1995
1997
1999
2001
Other exotic Hydrilla verticillata
Native No species data
*****
LTR
0
200
400
600
800
1000
1985
1987
1989
1991
1993
1995
1997
1999
2001
Pro
du
ctiv
ity
(hec
tare
s)
Other exotic Hydrilla
Native No species data
0
500
1,000
1,500
0 500 1,000 1,500
SAV productivy previous year (ha)
SA
V p
rod
uct
ivit
y (h
a)
UTR LTR UOE Linear (All segments)
0
0.5
1
1.5
2
0 1 2 3
Total nitrogen (mg l-1)
Div
ersi
ty in
dex
UTR LTR UOE Linear (All segments)
SAV productivity is density specific SAV coverage, in hectares
0
50
100
150
200
250
1959
1962
1965
1968
1971
1974
1977
1980
1983
1986
1989
1992
1995
1998
2001
Wa
terf
ow
l co
un
t h
r-1 e
ffo
rt
0
500
1000
1500
2000
2500
SA
V (
he
cta
res
)
Waterfowl * SAV
Period 1 Myriophyllum present
Period 3 SAV returns, Hydrilla dominant
Period 2 No SAV
*******
Period
Wat
erfo
wl c
ou
nt
hr
-1 e
ffo
rt
0
10
20
30
40
50
80
100Oxyura
jamaicensisAthya affinis
and A. marila
Anasplatyrhynchos
Brantacanadensis
Aythyavalisineria
Fulicaamericana
Anasrubripes
Mergusmerganser
1 2 3 1 2 3 1 2 3 1 2 3 1 2 3 1 2 3 1 2 3 1 2 3
Period 1 = 1959-1966Period 2 = 1966-1982Period 3 = 1982-2001
A
BB
A
BAB
A
BB A
B AB
A
BAB
A
B
C
A
B B
A
B
C
(Ruddy) (Scaup sp.)
(Mallard) (Canada Goose)
(Canvas-back)
(Common Merganser)
(American Black)
(American Coot)
Conclusions 1985-2001 Potomac River-
Productivity of native, as well as exotic, SAV species was shown to vary with factors affecting water column light attenuation (TSS, Chlorophyll a).
Winter waterfowl increased significantly with SAV coverage, despite dominance by exotics.
SAV productivity was largely driven by Hydrilla productivity 1985-2001
Previous years propagules (tubers, seeds, etc) may dampen the effect of environmental variation
Our findings support management strategies to improve water clarity and reduce nutrient concentration in order to protect diversity and waterfowl habitat
Exploring Causes of a Seagrass Transplant Failure in the Potomac River (Virginia) –Mitigation for loss of SAV at Wilson Bridge construction site
We monitored a seagrass transplant site (Judith Sound) and a reference site (Dameron Marsh), in VA. The transplant site was one of six SAV transplant sites in the Potomac that have only been marginally successful since transplanting began in 2000 (written communication, Justin Reel) .
March to November, of 2003 and 2004, at both sites we measured habitat variables monthly, including sedimentation and erosion, shoot length and burial, salinity, and light attenuation.
Natural eelgrass at reference site and eelgrass tranplanted in fall 02 and fall 03 (written communication, Justin Reel) did poorly in 2003 and 2004
Figure 1. Precipitation and salinity during 2003 and 2004 at the transplant site and reference site. Precipitation data from Norfolk International Airport
Exploring Causes of a Seagrass Transplant Failure in the Potomac River (Virginia) –Mitigation for loss of SAV at Wilson Bridge construction site
1) Both sites were above the median 22 percent light level
2) The percent of shoot that was buried was greater at the transplant site (22 percent) than at the reference site (11 percent), although both percentages were below levels shown to be detrimental to eelgrass survival (Veermaat and others 1997).
3) Monitoring data support the conclusion that salinity not erosion or accretion, were the primary factors responsible for the decline of eelgrass at both sites.
4) Low sediment fertility may also play a role in lack of success at the eelgrass transplant site.
Exploring Causes of a Seagrass Transplant Failure in the Potomac River (Virginia) –Mitigation for loss of SAV at Wilson Bridge construction site
2003 SAV
Maryland
Potomac integrative analysis will enhance USGS SAV studies and other potential studies to explain ecosystem change to help assess the effectiveness of restoration strategies
Relationship between environmental variables and species of SAV
Field investigations of SAV health, sediment characteristics, water quality, and maximum depth of SAV, w/ many cooperators
Tracking sediment sources using isotopic tracers (Allen Gellis, USGS)
Dameron Marsh natural SAV health as a reference site for SAV transplantsImage from MDDNR website
Wetland restoration and sediment accretion studies