Effects of Drought on Restored and
Reference Brackish Marshes in the
Northwestern Gulf of Mexico
Erin L. Kinney,
Anna R. Armitage and Antonietta Quigg
Texas A&M University at Galveston
Texas “Exceptional Drought” of
2010 – 2011
• Oct 2010 – Sept 2011 = driest 12 months on
record for the state of Texas
• Average of 11” (-16” from avg)
Objectives
• To evaluate effects of extreme drought in
Texas coastal systems
• Took advantage of ongoing monitoring project
in a brackish marsh restoration project
• Before/after impact of extreme drought on
brackish system
Study site
Lower Neches Wildlife Management Area
Texas
Lower
Neches
WMA
Louisiana
Florida
Lower Neches Restoration Location
• Chenier plain used to receive water via sheetflow, but highly disrupted
• Freshwater flow was reduced and salt water
introduced through construction of canals and
inter-coastal waterway
• Native vegetation largely died off, converted into
open water
• Mitigation is being undertaken to bring
vegetation back (2007)
• LNR site is now rain-fed with some tidal influence
• Brackish (typically 2 – 14 ppt)
Lower Neches Wildlife Management Area
Marsh
c.a. 1953
Lower Neches Wildlife Management Area
Open Water
c.a. 2006
Lower Neches Wildlife Management Area
Restored marsh
Reference marsh
c.a. 2008
Lower Neches Restoration
• Mounds built in 2007 – 2008
• Planted with Spartina alterniflora Vermilion
• Quarterly sampling
– Salinity and water quality
– Emergent vegetation
– Submerged aquatic
vegetation
– Fauna associated with
SAV
Summer 2007
Summer 2008
0
Ap 9
r0
Ju 9
n
0
Au 9
g
0
O 9
ct
0
Ja 9
n
1
Ap 0
r1
Ju 0
n
1
Se 0
p
1
Ja 0
n
1
Ap 1
r1
Ju 1
n
1
Se 1
p
1
Ja 1
n
1
Ap 2
r1
2
n
Ja
Salinity (ppt)
Salinity 3x higher than normal in summer 2011
30
Restored
Reference
25
20
15
10
5
0
Date
n
Ap 09
r0
Ju 9
n
Au 09
g
O 09
ct
J a 09
n
Ap 10
r
Ju 10
n
Se 10
p
Ja 10
n
Ap 11
r
Ju 11
n
Se 11
p
Ja 11
n
Ap 12
r1
2
Ja
Emergent vegetation density
(# stems/m2 )
Emergent vegetation density was not
affected by drought
2000
Restored
Reference
1500
1000
500
0
Date
09
pr
0
Ju 9
n
0
A 9
ug
0
O 9
ct
0
Ja 9
n
1
A 0
pr
1
Ju 0
n
1
S 0
ep
1
Ja 0
n
1
A 1
pr
1
Ju 1
n
1
S 1
ep
1
Ja 1
n
1
A 2
pr
12
A
Ja
n
S. alterniflora Chl a
(mg/ mg leaf)
S. alterniflora fitness did not change
during drought
0.5
Restored
Reference
0.4
0.3
0.2
0.1
0.0
Date
n
0
Ap 9
r0
Ju 9
n0
Au 9
g0
O 9
ct
0
Ja 9
n1
Ap 0
r1
Ju 0
n1
Se 0
p1
Ja 0
n1
Ap 1
r1
Ju 1
n
Se 11
p
J a 12
n
1
Ap 2
r1
2
Ja
Myriophyllum spicatum
dry biomass (g/m 2)
Aquatic: Myriophyllum spicatum
absent in spring 2011
1000
Restored
Reference
800
600
400
200
0
Date
0
Ap 9
r0
Ju 9
n
0
Au 9
g
0
O 9
ct
0
Ja 9
n
1
Ap 0
r1
Ju 0
n
1
Se 0
p
1
Ja 0
n
1
Ap 1
r1
Ju 1
n
1
Se 1
p
1
Ja 1
n
1
Ap 2
r1
2
n
Ja
Salinity (ppt)
Salinity 3x higher than normal in summer 2011
30
Restored
Reference
25
20
15
10
5
0
Date
600
Restored
Reference
500
400
300
200
100
0
Ja
n
0
Ap 9
r0
Ju 9
n0
Au 9
g0
O 9
ct
0
Ja 9
n1
Ap 0
r1
Ju 0
n1
Se 0
p1
Ja 0
n1
Ap 1
r1
Ju 1
n
Se 11
p
1
Ja 1
n
1
Ap 2
r1
2
Ruppia maritima dry biomass
(g/m2)
Ruppia maritima biomass may have
recovered slightly in response to M.
spicatum decline
Date
n
0
Ap 9
r0
Ju 9
n
0
Au 9
g
0
N 9
ov
0
Fe 9
b
1
M 0
ay
1
Se 0
p
1
Ja 0
n
1
Ap 1
r1
Ju 1
n
1
Se 1
p
11
Ja
2
Total fish density (#/m )
Fish density declined during drought
160
Restored
Reference
140
120
100
80
60
40
20
0
Date
Possible shifts in fish species present?
• General reduction in fish abundance, 10-fold
reduction in Poecilia latipinna
• Gulf menhaden Brevoortia patronus present
April – June 2011
Invertebrate density declined dramatically
– largely due to disappearance of the snail
Probythinella louisianae
Reference
600
500
400
300
200
100
n
09
Ap
r0
Ju 9
n
0
Au 9
g
0
N 9
ov
0
Fe 9
b
1
M 0
ay
1
Se 0
p
10
Ja
n
1
Ap 1
r1
Ju 1
n
1
Se 1
p
11
0
Ja
Invertebrate density
(#/m2)
Restored
Date
0
Ap 9
r0
Ju 9
n
0
Au 9
g
0
N 9
ov
0
Fe 9
b
1
M 0
ay
1
Se 0
p
1
Ja 0
n
1
Ap 1
r1
Ju 1
n
1
Se 1
p
11
n
Ja
Invertebrate density - no snails
(#/m2)
Invertebrate density, without snails,
was lower during drought
120
Restored
Reference
100
80
60
40
20
0
Date
Invertebrate species composition
changed beginning April 2011
• Probythinella louisianae decreased from
500/m2 at restored sites in September 2010
to 0/m2 in September 2011
• Penaeus aztecus (brown shrimp) appeared
in April 2011 (3-24/m2)
Summary
• Salinity was three times higher in June 2011
than in June 2010
• Emergent vegetation was not impacted by
drought
• SAV biomass was much lower in drought year
• Fish and invertebrates densities were much
lower in drought year
Drought and Construction Techniques Influence
Ecosystem-Level Restoration of a Brackish Marsh
Poster #345 Session 2 (Wed-Fri)
Conclusions and Implications
• Brackish systems are particularly susceptible to
extreme drought effects because of salinity changes
• Extreme drought affected SAV much more than
emergent vegetation
– Vermilion S. alterniflora was resistant to drought
conditions, including low rainfall and high salinity
– SAV biomass and faunal community declined during
drought, likely due to increased salinity
• Monitoring programs should include both emergent
vegetation and aquatic habitats
• Ecosystem services (refuge, wave dampening, nutrient
uptake by SAV) provided by aquatic habitats may be
impacted by extreme drought
Thanks!
Any questions?
• The Coastal Wetlands and Phytoplankton Dynamics teams at TAMUG
• Funding: TGLO Oil Spill Prevention & Response Division, TGLO Coastal
Management Program
• Texas Parks & Wildlife Department: Jim Sutherlin, Andrew Peters, and
Mike Rezsutek
• Chevron: Jim Myers and Jerry Hall
Lower Neches Restoration Location
Lower Neches Restoration Location
c.a. 2011