macro-tidal salt marsh ecosystem response to culvert - cbwes

R E S E A R C H A R T I C L E

Macro-Tidal Salt Marsh Ecosystem Response toCulvert ExpansionTony Bowron,1 Nancy Neatt,1 Danika van Proosdij,2,3 Jeremy Lundholm4 and Jennie Graham1

AbstractThe purpose of this paper was to examine the vegeta-tive, sedimentary, nekton and hydrologic conditions pre-restoration and the initial 2 years post-restoration at apartially restricted macro-tidal salt marsh site. Replace-ment of the culvert increased tidal flow by 88%. This wasinstrumental in altering the geomorphology of the site,facilitating the creation of new salt marsh pannes, expan-sion of existing pannes in the mid and high marsh zones,and expansion of the tidal creek network by incorporat-ing relict agricultural ditches. In addition, the increase inarea flooded resulted in a significant increase in nekton use,fulfilling the mandate of a federal habitat compensationprogram to increase and improve the overall availabilityand accessibility of fish habitat. The restoration of a morenatural hydrological regime also resulted in the die-off offreshwater and terrestrial vegetation along the upland edge

of the marsh. Two years post-restoration, Salicornia euro-pea (glasswort) and Atriplex glabriuscula (marsh orache),were observed growing in these die-back areas. Similarchanges in the vegetation community structure were notobserved at the reference site; however, the latter did con-tain higher species richness. This study represents the firstcomprehensive, quantitative analysis of ecological responseto culvert replacement in a hypertidal ecosystem. Thesedata will contribute to the development of long-term datasets of pre- and post-restoration, and reference marsh con-ditions to determine if a marsh is proceeding as expected,and to help with models that are aimed at predicting theresponse of marshes to tidal restoration at the upper endof the tidal spectrum.

Key words: Bay of Fundy, GPAC protocol, LiDAR, nekton,restoration monitoring, RSET.

Introduction

Over approximately the last 1,000 years, human activitieshave reduced the amount of salt marsh and free-flowing tidalriver habitats in many areas, including Europe (e.g., Toniset al. 2002; Elias & van der Spek 2006), North America(e.g., Wells 1999; Neckles et al. 2002), and Australia (e.g.,Wolanski et al. 2001). Conservative estimates for the Bay ofFundy put the loss of salt marsh habitat between 80 and 85%(Gordon 1989), mostly associated with diking and conversionto agricultural land. Although these activities are of historicaland social significance, it is now recognized that the significantloss of habitat, species, and primary productivity that hasresulted from the construction of dikes, modern tidal barriers(causeways), and coastal development has had significant

1 CB Wetlands and Environmental Specialists Inc., 37 Royal Masts Way, Bedford,Nova Scotia B4A 4B1, Canada2 Department of Geography, Saint Mary’s University, 923 Robie St., Halifax, NSB3H 3C3, Canada3 Address correspondence to D. van Proosdij, email [email protected] Department of Biology, Saint Mary’s University, 923 Robie St., Halifax, NSB3H 3C3, Canada

© 2009 Society for Ecological Restoration Internationaldoi: 10.1111/j.1526-100X.2009.00602.x

ecological implications, which are preventable and repairable(Sinicrope et al. 1990; Burdick et al. 1997).

Salt marsh ecosystem function may be restored passivelywhen a dike is breached during a storm with little to no humaninterference (Crooks et al. 2002) or through active meansby planned removal or modification of a barrier to restorehydrology (Klotzli & Grootjans 2001). Examination of passiverestoration sites can provide long-term records about vege-tation and geomorphic recovery (Crooks et al. 2002; French2006; Byers & Chmura 2007); however, this provides lim-ited information about driving and/or limiting variables withinthe first few years after the breach event that may influ-ence the ultimate recovery of the system (e.g., Klotzli &Grootjans 2001; Able et al. 2008). Both the European andNorth American experiences have shown that salt marsh re-establishment is not inevitable at all sites following a breach(e.g., Haltiner et al. 1997; French et al. 2000; Klotzli & Groot-jans 2001; Williams & Orr 2002). Properly monitored restora-tion projects can sometimes provide additional informationon constraints that may have caused a restoration project toproceed along successional pathways not initially anticipated(Klotzli & Grootjans 2001). Constraints include inadequatesedimentation or hydrology, high groundwater salinity, lownutrient levels, erosion, and lack of appropriate seed source

Restoration Ecology 1

Marsh Response to Culvert Expansion

(e.g., Burdick et al. 1997; Haltiner et al. 1997; Williams &Orr 2002; French 2006).

Tidal wetlands are valuable ecosystems and their restora-tion has become a common practice in the Gulf of Maine overthe past two decades (Short et al. 2000; Neckles et al. 2002;Konisky et al. 2006). In Atlantic Canada, salt marsh restora-tion is in its infancy and although decommissioning projectshave been conducted by non-government organizations such asDucks Unlimited Canada (DUC) and government departmentssuch as Nova Scotia Department of Agriculture over the lastdecade, no formal salt marsh restoration projects with associ-ated monitoring programs were undertaken until this study.The Cheverie Creek (CHV) restoration project, undertakenby the Nova Scotia Department of Transportation and Infras-tructure Renewal (NSTIR) as a Habitat Compensation Project(”Harmful Alteration Disruption or Destruction of Fish Habi-tat” [HADD]), represents the first fully monitored, active saltmarsh restoration project undertaken in Atlantic Canada. As aHADD it must include a long-term (6-year) monitoring pro-gram to ensure project success.

We examined the hydrologic, sedimentary, vegetative, andnekton conditions pre-restoration and the initial 2 years post-restoration at a macro-tidal salt marsh site. A modified formof the Global Program of Action Coalition for the Gulf ofMaine Regional Monitoring Protocol (GPAC protocol) wasemployed (Neckles et al. 2002). Although culvert replacementprojects are a popular restoration practice in the Gulf ofMaine Region (Konisky et al. 2006), this study was the firstcomprehensive, quantitative data set of ecological responseto culvert replacement in a high macro-tidal ecosystem. Thegoals of the study were to evaluate the rate of vegetationrecovery after culvert replacement and to assess the influenceof marsh morphology, sediment dynamics, and hydrologyin re-establishing conditions and processes critical for self-maintenance of tidal marshes and fish habitat. We hypothesizedthat increasing the size of the culvert would permit naturalmarsh functions to be enhanced. In addition, we determinedif and how monitoring protocols need to be adapted inenvironments where abiotic factors are at the extreme range(e.g., tides and ice). Given the paucity of reference salt marshesin the region, we also evaluated the adequacy of a singlereference site as a control.

MethodsStudy Site

The Bay of Fundy is an extension of the Gulf of Maine, onthe east coast of Canada. It is a high macro-tidal estuarywith semidiurnal tides that may exceed 15 m, exposingextensive intertidal mud flats at low tide. Suspended sedimentconcentrations within the Minas Basin in the upper Bay arehigh, ranging from 150 mg/L over the marsh surface (vanProosdij et al. 2006a) to 4,000 mg/L (Amos & Tee 1989)in the Basin. This inorganic material contributes to the highsedimentation rates recorded on marshes within the region(e.g., Chmura et al. 2001; van Proosdij et al. 2006a, 2006b)

and their minerogenic nature. The CHV (45◦09′31.44′N,64◦10′09.84′W) marsh is located on the southern shore of theMinas Basin in the upper reaches of the Bay of Fundy. Thewater depth over the marsh during high tides can be upwardsof 1–1.5 m. In the winter, rafted ice floes can become trappedon the marsh surface, depositing sediment and root rhizomematerial in the spring (van Proosdij et al. 2006b).

The monitoring program was conducted on the front 29.5ha of CHV, with the majority of monitoring activities focusedon the north side of the creek. Highway 215 crosses the mouthof the CHV by way of a two-lane causeway-culvert structure.Historically, this system was diked (approximately 200 yearsago) and used for agricultural purposes. There are remnants ofthe abandoned dike on both sides of the main creek, runningperpendicular to the creek. The causeway was originallyconstructed approximately 50 m seaward of the dike with asmall bridge section spanning the main creek channel. Thebridge was replaced by a wooden box culvert with flap gate in1960, completely restricting tidal flow. Encroachment of tree,shrub, and freshwater species occurred over approximately 25years until tidal flow was partially restored when the flap gatewas removed unintentionally in the early 1980s. Tidal flowwas partially restricted at this time, causing a significant (1m) tidal restriction for spring tides, allowing tidal flow to 4–5ha of the marsh surface. Restoration activities consisted ofthe replacement of the remnants of the wooden box culvert(Fig. 1a) with a 9.2 × 5.5–m elliptical aluminum culvert(Fig. 1b), increasing the culvert opening approximately 7-foldfrom 4.7 to 32.6 m2. This restored tidal flow to 43 ha (430,000m2) of former marsh surface on spring tide events. This site isdirectly behind the causeway, which protects the marsh edgesfrom wave action (Fig. 2).

The zonation of the CHV vegetation community resemblesthat of other Fundy salt marshes such as Allen Creek (45◦52′N,64◦21′W; van Proosdij et al. 1999) and Dipper Harbour(45◦06′N, 66◦26′W; Byers & Chmura 2007). The majority ofthe marsh surface is of the high marsh variety, with low marshfringing the main creek and some marsh surface pannes anddrainage channels (Fig. 2).

The reference site for this compensation site is BassCreek (CHV-R), located in Bramber, 5 km North of CHV(45◦11′55.24′N, 64◦07′58.11′W). Highway 215 also crossesthe mouth of this creek with a causeway-bridge combination.The bridge spans the width of the creek and does not restricttidal flow. The study area at CHV-R is 5.9 ha.

Field Methods

A pre- and post-restoration monitoring program was devel-oped for the CHV Salt Marsh Restoration Project in 2005(Bowron & Chiasson 2006), which was based on the GPACprotocol with elements drawn from other programs/studies.The program involved a minimum of 1 year pre- and 5 yearspost-restoration data collection for a series of physical andbiological parameters within the ecological indicator cate-gories of hydrology, soils and sediments, vegetation, fish, andinvertebrates. The indicator categories, physical and biological

2 Restoration Ecology


(a) (b)

Figure 1. (a) Old box culvert at CHV in 2002 and (b) new culvert installed in December 2005.

Figure 2. Sampling design for first 8 of 26 lines at CHV superimposed over LiDAR elevations. LiDAR provided by T. Webster of the AdvancedGeomatics Research Group at COGS, 2007. Elevations expressed relative to CGVD28 vertical datum.



Tab

le1.

The

Che

veri

eC

reek

Salt

Mar

shR

esto

ratio

nm

onito

ring

prog

ram

,inc

ludi

ngco

rean

dad

ditio

nale

colo

gica

lind

icat

ors,

met

hodo

logi

es,a

ndth

esi

te-s

peci

ficap

plic

atio

n(X

:all

site

s;C

–C

HV

-R).

Pos

t

Cat

egor

yP

aram

eter

sSa

mpl

ing

Met

hod

Ann

ual

Sam

plin

gF

requ

ency

Pre

Yr

1Y

r2

Hyd

rolo

gyH

ydro

logy

sign

alD

aily

max

imum

wat

erle

vel

(man

ual

wat

erle

vel

reco

rder

),co

ntin

uous

(1-

or5-

min

ute

inte

rval

s)w

ater

leve

lre

cord

ers

(Sol

inst

Lev

elog

ger

Mod

el30

01)

Dai

lym

axim

ums:

CH

V:

18Se

ptem

ber–

2O

cto-

ber

2003

Con

tinu

ous

wat

erle

vel:

CH

V(5

min

utes

):3

Nov

embe

r–24

Nov

embe

r20

06;

CH

V(1

min

ute)

:19

Nov

embe

r–19

Dec

embe

r20

07;

and

CH

V-R

(5m

inut

es):

19D

ecem

ber

2006

–9

Janu

ary

2007

X—

X

Dep

thto

grou

ndw

ater

Gro

undw

ater

wel

ls(0

.02

m×

1m

sam

pled

atde

pth

0.9

m)

CH

Van

dC

HV

-R:

biw

eekl

yJu

ly–

Nov

embe

r20

03;

July

–N

ovem

ber

2004

;m

onth

lyfr

omJu

lyto

Sept

embe

r20

06an

dJu

lyto

Sept

embe

r20

07

XX

X

Pore

wat

ersa

linity

Gro

undw

ater

wel

ls;

sipp

erC

HV

and

CH

V-R

:bi

wee

kly

July

–N

ovem

ber

2003

;Ju

ly–

Nov

embe

r20

04;

mon

thly

from

July

toSe

ptem

ber

2006

and

July

toSe

ptem

ber

2007

XX

X

Soi

lsan

dse

dim

ents

Sedi

men

tel

evat

ion

Rod

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men

tE

leva

tion

Tabl

es(R

SETs

)C

HV

:fou

rsta

tions

,ins

talle

dJu

ne20

05,m

easu

red

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embe

r20

05,

2006

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d20

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HV

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two

stat

ions

inst

alle

dSe

ptem

ber

2006

,on

est

atio

nin

stal

led

Oct

ober

2006

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easu

red

Oct

ober

2006

and

2007

XX

X

Sedi

men

tac

cret

ion

Sedi

men

tpl

ates

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arke

rho

rizo

ns(t

hree

per

RSE

T)

sam

pled

usin

ga

cryo

geni

cco

rer

(Cah

oon

etal

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96)

Sedi

men

tpl

ates

—C

HV

:25

loca

tion

s;m

onth

lyfr

omJu

lyto

Dec

em-

ber

2002

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lyto

Oct

ober

2003

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nuar

yto

Nov

embe

r20

04;

annu

ally

July

2005

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06an

d20

07M

arke

rho

rizo

ns—

CH

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inst

alle

dJu

ne20

05,

mea

sure

dSe

ptem

ber

2006

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7C

HV

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lled

Oct

ober

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red

Oct

ober

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XX

X

Sedi

men

tch

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teri

stic

s(b

ulk

dens

ity,

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nic

mat

ter

cont

ent,

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men

tty

pe)

Sedi

men

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pair

edsa

mpl

es:

(30

mL

syri

nge

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tan

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×15

–cm

core

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CH

V:

25pa

ired

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ples

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ly20

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ired

sam

ples

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Tab

le1.

Con

tinue

d.

Pos

t

Cat

egor

yP

aram

eter

sSa

mpl

ing

Met

hod

Ann

ual

Sam

plin

gF

requ

ency

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Yr

1Y

r2

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etat

ion

Com

posi

tion

Abu

ndan

ceH

eigh

tPo

int

inte

rcep

tm

etho

d(1

-m2

plot

s)C

HV

:12

9pl

ots,

annu

ally

Aug

ust

2002

,A

ugus

t20

04,

Aug

ust

2006

,A

ugus

t20

07C

HV

-R:

27pl

ots,

annu

ally

Aug

ust

2003

,A

ugus

t20

06,

Aug

ust

2007

XX

X

Nek

ton

Com

posi

tion

Spec

ies

rich

ness

Den

sity

Len

gth

Min

now

trap

sin

pann

es,

tidal

cree

ks,

and

mai

nch

anne

l(s

mal

lfis

h);

beac

hse

ine

(30

m×

1m

;6

mm

mes

hsi

ze)

onm

arsh

surf

ace

(all

size

s)

All

site

s:sp

ring

tide

.Fou

rm

inno

wtr

aps

and

thre

epu

lls

wit

hbe

ach

sein

epe

rsa

mpl

ing

date

CH

V:

18O

ctob

er20

05;

17A

ugus

t20

06,

8Se

ptem

ber

2006

,6O

ctob

er20

06;2

007

and

CH

V-

R:

19O

ctob

er20

05;

11Se

ptem

ber

2006

,7

Oct

ober

2006

;20

07

XX

X

Inve

rteb

rate

sL

arva

lm

osqu

ito(a

bund

ance

)Si

xdi

psa

mpl

espe

rpa

nne

(dip

per)

CH

V:

10pa

nnes

;m

onth

lyfr

omJu

neto

Sept

em-

ber

2004

;m

onth

lyfr

omJu

lyto

Sept

embe

r20

05;

6Ju

ly20

06,

20Ju

ly20

06,

14A

ugus

t20

06;

mon

thly

from

June

toSe

ptem

ber

2007

CH

V-R

:m

onth

lyfr

omJu

neto

Sept

embe

r20

04;

mon

thly

from

July

toSe

ptem

ber

2005

;6

July

2006

,20

July

2006

,14

Aug

ust

2006

;m

onth

lyfr

omJu

neto

Sept

embe

r20

07

XX

X



parameters, data collection methods, and sampling frequencyare described in Table 1.

Sampling was conducted at all sites using transects estab-lished in a non-biased, systematic sampling design tied intosurveyed benchmarks. Twenty-six were established at CHV(Fig. 2) and eight at CHV-R. Data collection was conductedat sampling stations established at equal intervals along eachtransect, and surveyed with the Total Station.

Hydrology

A digital elevation model (DEM) was produced for eachsite using a 2004 1:10,000 aerial photograph, and elevationsurvey data collected using a combination of differentialglobal position system (DGPS), Leica TCR-705 Total Station,and 2007 LiDAR data (Fig. 2). All topographic data werereferenced to the Canadian Geodetic Vertical Datum 1928(CGVD28). The hydroperiod and summary hypsometric curvefor each site were modeled using the tidal signal and DEM forthe marsh surface (Table 1).

Depth to groundwater was sampled using seven ground-water wells installed adjacent to vegetation stations at CHV(Fig. 2), and six at CHV-R. A single measurement (centime-ters below marsh surface) was taken at each station during lowtide (Table 1).

Soils and Sediments

The location and frequency of pore water salinity samplingat all sites were matched with depth to groundwater sam-pling (Fig. 2). Salinity was measured at shallow (0.15 m)and deep (0.45 m) wells using a handheld refractometer(2003–2004). In 2005, the salinity well method was replacedby the use of a soil probe (sipper) (Roman et al. 2001). Due tothe high sediment concentration of water samples collected bythe sipper, samples were bottled and returned to the lab andallowed time for the sediment to settle out before a refrac-tometer reading was taken.

Marsh surface elevation change (+/ − 0.001 m) was mea-sured once per year using four rod sediment elevation tables(RSETs; Cahoon et al. 2002) at CHV and three at CHV-R. Allmeasurements were taken at low tide and at the same time inthe growing season (September) to minimize the influence ofevapotranspiration (Paquette et al. 2004).

Vertical accretion at all sites was measured using feldsparmarker horizons and a cryogenic corer as described by Cahoonet al. (1996). Three 0.5-m2 marker horizons per RSET stationwere established at each site (Table 1). In 2002, twenty-five10 × 20–cm aluminum plates were inserted 10 cm below themarsh at CHV (Fig. 2) according to the design, installation,and sampling method described in van Proosdij et al. (2006a).

Sediment cores (bulk density, organic matter [OM], andgrain size) were collected using a stratified random samplingprocedure paired with vegetation sampling plots (Fig. 2;Table 1). OM content was determined by loss on ignition(LOI), while grain size was analyzed using a Coulter LS200.

Vegetation

The marsh vegetation community was surveyed using perma-nent 1-m2 plots. A detailed vegetation survey (species com-position, percent cover, and height) was conducted at CHVin 2002 on the 92 plots on the first eight transects (Fig. 2).This method was replicated in 2004 on the remaining 27 plotsat CHV as well as on the 27 at CHV-R. Plots sampled in2002 were combined with plots sampled in 2004 to assess thepre-restoration condition. Post-restoration species compositionand abundance were determined within each plot using a pointintercept method (abundance = frequency of contact of eachspecies with 25 points within plot) (Roman et al. 2001).

Mean plot species richness and cover of bare ground werecompared between sites and years using repeated measuresanalysis of variance (ANOVA). Differences in vegetationcomposition were assessed using nonparametric multivariateANOVA (NPMANOVA), with species abundances as depen-dent variables (including only species occurring in five or moreplots; 100 permutations) (Anderson 2001).

Nekton

A beach seine and a set of four minnow traps were usedto sample nekton on the marsh surface, pannes, and tidalcreeks during spring tide events. Sampling with the beach seinewas conducted according to the methodology developed andused by the Community Aquatic Monitoring Project (CAMP)(Weldon et al. 2005). Smaller species in the salt pannes andtidal creeks were sampled using the minnow traps. The trapswere deployed before high tide and retrieved once the tidelevel had dropped (approximately 3.5 hours). Nekton densitymeasures were limited to samples of known area (i.e., minnowtrap excluded) (Konisky et al. 2006).

All captured specimens were held in buckets, identified tospecies level, counted (to a maximum of 300 per species), andmeasured for length (15 individuals per species).

ResultsHydrology

Based on the 2007 tidal signal data, LiDAR, and on-sitemeasurements including observed tree die-off, the total areaof recovering marsh at CHV has increased approximately 8-fold from 5 to 43 ha (Fig. 3). A comparison of the upstreamtidal signal to the downstream tidal signal (Table 1) indicatesthat the new culvert has eliminated the tidal restriction on alltides under 7.1 m (CGVD28) (85% of tides).

There was no significant difference in depth to watertable between pre- and post-measures at CHV (t test, t =1.20, df = 40, p = 0.235); however, depth to water table atCHV-R was significantly deeper than observed at CHV for allyears (t test, t = −3.16, df = 52, p = 0.003). The detectabledifference was therefore spatial in nature and there was notemporal change. Both sites showed strong seasonal trends,with the greatest depths to water table recorded in July.



Figure 3. Hypsometric curves pre- and post-restoration at CHV and baseconditions at CHV-R. Original culvert restricted tides to less than 6 mabove geodetic datum, new culvert permits tides up to 7.1 m.

Soils and Sediments

Average soil salinity ranged between 1 and 31 ppt at CHV-Rand 0–36 ppt at CHV and were generally lower in the summerand increasing in the fall (Fig. 4). Mean pore water salin-ity levels at CHV post-restoration were significantly higher (ttest, t = −6.78, df = 72, p = 2.75E−09) than pre-restorationlevels. The largest changes in salinity were observed at thehigh marsh stations and those further upstream. In addition,mean pore water salinities at CHV were found to be signif-icantly higher than those of CHV-R (t test, t = 14.15, df =77, p = 4.00E−23) in the same year. Pre-restoration, at CHV,no significant differences were detected between shallow anddeep wells (t test, t = −0.388, df = 134, p = 0.698). Whenthe shallow wells at CHV and CHV-R were compared, nosignificant difference was observed (t test, p < 0.174); how-ever, there was a significant difference (t test, t = 11.02, df =45, p = 2.23E−14) measured between the deep wells at bothsites (CHV > CHV-R). A significant difference was detectedpost-restoration between the shallow and deep samples at CHV(t test, t = 2.11, df = 26, p = 0.041).

A trend of decreasing bulk density and increasing organicmatter content with increasing geodetic elevation and distancefrom the main creek was observed both pre- and post-restoration at CHV (Fig. 5a & 5b). One year post-restorationthere was a minor increase in bulk density across the marsh(up to CHV-R levels) and a decrease in organic matter whencompared to pre-restoration conditions. Pre-restoration, CHVrecorded an increase in mean grain size with increasingelevation and distance from the main tidal creek (Fig. 5c).Post-restoration, mean grain size decreased with increasingelevation, but exhibited no discernable pattern at CHV-R.

The mean net change in surface elevation at CHV washighly variable both at a station between years and betweendifferent sites across the marsh within the same year (Table 2).After the first year, all of the sediment plates installed within

the first 0.5 m of the tidal creek were lost due to erosion,likely due to ice scour. There was no significant differencebetween pre- and post-sediment accretion rates using plates(paired t test: t = 1.2108, df = 12, p = 0.249). The mean pre-restoration accretion rate was 0.7 ± 0.5 cm/year comparedwith a 0.4 ± 0.5 cm/year rate from 2005 to 2007 (Table 2).

Table 2. Mean rate of change in marsh surface elevation measured at sed-iment plates at CHV pre- (2002–2005) and post-restoration (2005–2007).

Mean Rate of Change (cm/yr± SD)

Station Elevation (m) Pre Post

L1S2 4.4 0.7 ± 0.1 NAL1S6 4.8 0.3 ± 0.3 10.9 ± 4.9L1S8 5.1 0.4 ± 0.2 0.5 ± 0.3L2S6 6.2 1.1 ± 0.6 NAL3S2 4.2 0.7 ± 0.2 1.2 ± 0.5L3S4 5.2 1.3 ± 0.3 1.0 ± 0.9L5S2 4.6 0.7 ± 0.6 0.4 ± 0.4L5S4 5.6 2.0 ± 0.4 –1.3 ± 1.5L5S6 6.0 1.2 ± 0.2 0.3 ± 1.1L5S2(S) 6.1 0.5 ± 0.2 0.2 ± 0.1L7S2 5.6 0.4 ± 0.2 –0.4 ± 0.1L7S5 6.4 0.2 ± 0.3 0.2 ± 0.2L7S8 6.2 0.1 ± 0.2 NAL7S14 7.1 0.6 ± 0.2 1.1 ± 0.5L8S3 4.8 0.7 ± 0.0 0.4 ± 0.3L8S5 5.1 0.7 ± 0.2 0.0 ± 0.5Overall mean 0.7 ± 0.5 0.4 ± 0.7

All elevations relative to CGVD28 datum. NA = plate was not relocated post-restoration. Only stations that survived at least 1 year were included in the analysis.See Figure 2 for location of stations.

Since the RSET stations were not installed until 2005,no RSET data are available pre-restoration. One year post-restoration, the change in surface elevation was highest atRSET-02 and RSET-03, both with a net rate of change of2.2 cm/year (Fig. 6). The lowest recorded change in surfaceelevation was in the sedge community at RSET-04 with 0.6 ±0.1 cm/year (± SE). Both marker horizons and buried plates(within a 30 m radius of RSETs) were within the same range ofaccretion values (Fig. 6). Subtracting the marker horizon datafrom the RSET measurement leaves 0.35 cm to subsurfaceprocesses. The lowest value (0.63 cm/year) was at RSET-04indicating minimal subsurface processes at work. RSET-02had the highest change in surface elevation attributable tosubsurface processes (1.23 cm/year), which could be due topore water flux given its proximity to the tidal creek (Fig. 6).

Two years post-restoration, the 2005–2006 elevation trendswere repeated with slightly lower values (Fig. 5). There wasno significant difference between years (2006 vs. 2007) atCHV (t test: t = 1.6646, df = 3, p = 0.1946). However, sta-tistically significant differences in changes in surface elevationwere recorded between CHV (mean ± SE = 1.22 ± 0.08) andCHV-R (mean ± SE = 0.26 ± 0.03) (t test: t = −3.62, df =3.7, p = 0.025) in 2007.



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Figure 4. Change in mean pore water salinity at (a) deep and (b) shallow wells for CHV and CHV-R from 2002 to 2007.

Vegetation

Increased tidal inundation had the almost immediate effectof causing visible die-off of non-salt tolerant vegetationat the upper edge of the marsh (Fig. 7). Since the areainundated exceeded initial estimates, no sampling stations werelocated within the upper limits of inundation at high springtides. However, 2 years post-restoration, two primary saltmarsh colonizers, Salicornia europea (glasswort) and Atriplexglabriuscula (marsh orache), were observed growing in thesedie-back areas.

Species density (SD) has been consistently greater atCHV-R (Fig. 8a) (t tests: pre: t = 2.75, p = 0.01; 2006 : t =5.02, p = 0.0001; 2007 : t = 2.38, p = 0.02). Repeated mea-sures analysis shows a significant site by year interaction(F[2] = 3.9473, p = 0.008) (Table 3), which is caused by thedecline in SD at CHV immediately following reintroductionof tidal flow that recovered to pre-restoration levels by thesecond year post-restoration. The increase between year oneand year two post-restoration is due to the colonization ofCHV by more native halophytic species. The greater overall



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Figure 6. Mean annual change in surface elevation recorded at RSETs (± SE) and mean sediment accretion based on the marker horizons and sedimentplates (within area of RSETs) for the first 2 years post-restoration at CHV. Elevations expressed relative to CGVD28 datum.



Figure 7. Areas of change in vegetated community, panne expansion, and extent of die-off 2 years post-culvert replacement calculated from 2007LiDAR survey and on-site tide record. LiDAR provided by T. Webster of the Advanced Geomatics Research Group at COGS, 2007. Elevationsexpressed relative to CGVD28 vertical datum.

SD at CHV-R can be attributed to a number of uncommonspecies such as Solidago sempervirens (seaside goldenrod) andPlantago maritima (seaside plantain) that are more frequentat CHV-R. These are typically found in the upper marsh/saltmeadow areas where the dominants are Carex palacea (saltmarsh sedge) and Spartina pectinata (prairie cordgrass). Thesespecies do occur at CHV but less frequently; thus, they are lesslikely to contribute to greater average SD. Overall, speciesrichness (SR) (total number of species encountered in plots)was usually greater at CHV than CHV-R, but not consistentamong years (pre: 24 vs. 18, year 1 post: 20 vs. 22, and year 2post: 24 vs. 19). The amount of unvegetated area (bare ground)has been dynamic at both sites, with the formation of pannesbeing one of the main processes responsible for this. In bothyears post-restoration, there was a greater area of bare groundat CHV (site by year interaction: F[2] = 3.6579, p = 0.013)(Table 3; Fig. 8b).

The two sites had similar plant communities pre-restorationand year one post (NPMANOVA for site differences: pre-restoration F[1] = 1.592, p = 0.19; year 1 post F1 = 0.939,

Table 3. Repeated measures ANOVA for (a) species density and (b)unvegetated area.

(a)

Factor df SS MS F P

Site 1 148.97 148.97 24.846 <0.00001Residuals 128 767.46 6.00Year 3 15.12 5.04 4.3134 0.005Site × year 3 13.83 4.61 3.9473 0.008Residuals 384 448.55 1.17

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Site 1 123.5 123.5 0.5636 0.45Residuals 128 28046.6 219.1Year 3 1817 606 4.7095 0.003Site × year 3 1411 470 3.6579 0.013Residuals 384 49376 129

df = degrees of freedom; SS = sum of squares; MS = mean square.



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p = 0.37) but differed in year two post (year 2 post F[1] =2.862, p = 0.03). These differences are attributable to greaterabundances of Spartina alterniflora (smooth or salt marshcordgrass) and Spartina patens (salt meadow cordgrass) atCHV in year two post (Table 4). Plant communities alsochanged more over time in CHV compared with CHV-R(Table 4). In general, upland and dune vegetation at CHVbecame upper marsh/salt meadow vegetation characterized byC. palacea and S. pectinata. The change in vegetation compo-sition at CHV also reflected the increasing dominance of saltmarsh vegetation (S. alterniflora and S. patens) (Table 4).

Nekton

Post-restoration, five species of fish were caught, which istwo species less than was encountered prior to restoration

(Table 5). It is likely that the presence of Fundulus diaphanousduring pre-restoration and its absence during post-restorationsampling was due to misidentification of individuals dur-ing the initial year of survey work (later identified as Fun-dulus heteroclitus [mummichog]). Fundulus heteroclitus andMenidia menidia (Atlantic silverside) were consistently thedominant species at both sites during all sampling periods.However, at CHV, F. heteroclitus represented the largest per-centage of fish (56–95%) caught, whereas at the referencesite, M. menidia dominated (73–94%) (Table 5). There was amarked increase in the density of fish between pre- and post-restoration conditions, particularly within the pannes at CHV(Table 5).

Discussion

Culvert replacement resulted in an 8-fold increase in the areaflooded upstream of the causeway, significantly increasingthe area available for fish habitat and salt marsh ecosystemdevelopment thereby fulfilling the mandate of the HADDsproject. The increased hydrology, and its interaction withexisting marsh morphology, re-established conditions andprocesses critical for self-maintenance of tidal marshes andfish habitat. This was reflected by rapid changes in veg-etation community composition and development of newpannes.

As with most salt marsh restoration projects (e.g., Onaindiaet al. 2001; Hinkle & Mitsch 2005; Wolters et al. 2005a), theprimary variables driving the ecosystem response are hydrol-ogy and surface topography or elevation. Elevation relativeto the tidal frame has been known to be a primary determi-nant of vegetation colonization and succession (e.g., Boumanset al. 2002; Crooks et al. 2002). The restoration of a morenatural hydrological regime to CHV resulted in changes inthe biological community. The most visible indicator of thischange continues to be the die-off of freshwater and terres-trial vegetation (trees) along the upland edge of much of themarsh and recolonization by early successional salt marshspecies. In addition, there was a marked decline in the numberof freshwater and upland vegetation species and an increasein the abundance of halophytic vegetation (Spartina alterni-flora, Spartina patens, and Juncus gerardii ). While disper-sal limitations and/or competition with pre-existing vegetationcould still affect the salt marsh vegetation expansion at CHV,this study shows that vegetation recovery can be rapid whensources for recolonization are nearby and shifts in abiotic con-ditions result in mortality of terrestrial vegetation. The ratesof vegetation change within the first 2 years were rapid andcomparable to other culvert replacement projects (e.g., Burdicket al. 1997; Konisky et al. 2006).

The pre-restoration geomorphology of the site also con-tributed to the patterns of vegetation change and created con-ditions favorable for growth of halophytic vegetation and fishhabitat. For example, a new panne developed in an old filled-inoxbow. No new tidal creek channels were incised as have beenrecorded in other systems (Williams & Orr 2002; D’Alpaos



Table 4. Mean and standard error of plant cover (%) found at CHV and CHV-R pre- and post-restoration.

Pre-restoration

Species Name Short Form

Agrostis stolonifera Agr.sto 0.00 0.00 0.00 0.00 0.09 0.04 0.14 0.10 1.82 0.48 0.60 0.49

Algae Algae 0.00 0.00 0.88 0.91 0.00 0.00 0.98 0.76 0.00 0.00 1.47 0.82

Ammophila breviligulata Amm.bre 0.14 0.05 0.70 0.52 5.64 1.57 1.32 0.98 0.00 0.00 0.00 0.00

Ascophyllum nodosum* Asc.nod 0.00 0.00 0.00 0.00 0.36 0.17 0.00 0.00 0.00 0.00 0.11 0.11

Aster subulatus Ast.sub 0.00 0.00 0.04 0.05 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00

Atriplex glabriuscula Atr.gla 0.14 0.06 0.51 0.17 0.27 0.09 0.19 0.12 0.55 0.17 1.47 0.72

Calestygia sepium Cal.sep 0.00 0.00 0.00 0.00 0.36 0.17 0.00 0.00 0.09 0.04 0.11 0.11

Carex hormathodes Car.hor 0.00 0.00 0.00 0.00 0.00 0.00 0.14 0.15 0.00 0.00 0.00 0.00

Carex palacea Car.pal 2.37 0.83 1.50 0.86 5.27 1.77 2.42 1.11 11.45 2.53 6.60 2.13

Daucus carota Dau.car 0.00 0.00 0.09 0.09 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00

Distichlis spicata Dis.spi 0.00 0.00 0.00 0.00 3.73 1.57 0.93 0.88 2.00 0.63 1.23 0.63

Elymus repens Ely.rep 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 2.91 0.92 0.00 0.00

Elymus trachycaulus Ely.tra 0.00 0.00 0.00 0.00 1.18 0.50 0.04 0.04 0.00 0.00 0.00 0.00

Euthamia graminifolia Eut.gra 0.00 0.00 0.00 0.00 1.82 0.68 0.00 0.00 0.00 0.00 0.00 0.00

Festuca rubra Fes.rub 0.00 0.00 0.00 0.00 0.18 0.06 0.00 0.00 0.09 0.04 0.53 0.45

Glaux maritima Gla.mar 0.06 0.02 0.00 0.00 1.27 0.44 0.04 0.03 1.82 0.49 0.00 0.00

Juncus arcticusssp. Balticus Jun.arc 0.00 0.00 0.00 0.00 5.64 1.77 0.00 0.00 5.45 1.78 1.00 0.78

Juncus brevicaudatus Jun.bre 0.00 0.00 0.00 0.00 0.36 0.17 0.00 0.00 0.00 0.00 0.00 0.00

Juncus effusus Jun.eff 0.05 0.02 0.00 0.00 4.18 1.91 0.00 0.00 0.00 0.00 0.00 0.00

Juncus gerardii Jun.ger 10.73 2.69 8.10 2.31 21.55 3.50 16.74 3.34 34.64 4.00 11.60 2.84

Lathyrus martima Lat.mar 0.00 0.00 0.02 0.01 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00

Limonium nashii Lim.nas 0.55 0.21 0.64 0.29 0.64 0.18 0.82 0.38 0.18 0.08 0.56 0.24

Mentha sp. Mentha 0.00 0.00 0.04 0.05 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00

Mysotis laxa Myo.lax 0.00 0.00 0.02 0.02 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00

Plantago maritima Pla.mar 0.64 0.22 0.21 0.22 7.64 2.14 0.00 0.00 8.73 2.34 0.05 0.04

Potentilla simplex Pot.sim 0.00 0.00 0.22 0.23 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00

Puccinellia maritima Puc.mar 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.02 0.02

Rosa virginiana Ros.vir 0.00 0.00 0.28 0.21 0.00 0.00 0.02 0.02 0.00 0.00 0.00 0.00

Rubus strigosa Rub.str 0.00 0.00 0.04 0.05 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00

Ruppia maritima Rup.mar 0.00 0.00 0.00 0.00 0.00 0.00 0.60 0.37 0.00 0.00 0.39 0.40

Salicornia europaea Sal.eur 0.06 0.02 2.91 1.32 0.09 0.04 0.09 0.05 0.00 0.00 0.67 0.25

Scirpus acutus Sci.acu 0.00 0.00 1.22 0.97 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00

Solidago sempervirens Sol.sem 0.32 0.06 1.96 1.05 9.00 1.63 1.72 0.84 8.09 1.89 0.88 0.38

Spartina alterniflora Spa.alt 10.78 2.13 24.78 3.94 25.27 3.83 31.81 4.10 25.73 4.04 34.65 4.28

Spartina patens Spa.pat 37.45 3.35 42.60 4.26 36.55 4.12 42.56 4.53 40.91 4.46 51.63 4.52

Spartina pectinata Spa.pec 0.23 0.10 0.00 0.00 0.00 0.00 0.81 0.84 9.82 2.41 3.56 1.67

Sueda maritima Sue.mar 0.05 0.02 0.01 0.01 0.73 0.26 0.00 0.00 0.73 0.26 0.93 0.40

Symphotrichum lanceolatus Sym.lan 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 2.73 1.01 0.00 0.00

Symphotrichum novii-belgii Sym.nov 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.23 0.22

Triglochin maritima Tri.mar 0.00 0.00 0.00 0.00 0.00 0.00 0.07 0.07 0.18 0.08 0.14 0.11

Trifolium sp. Trifolium 0.00 0.00 0.02 0.02 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00

Typha latifolia Typ.lat 0.00 0.00 0.00 0.00 0.00 0.00 0.56 0.55 0.00 0.00 0.63 0.56

CHV-R

mean SE mean SE

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mean SE mean SE

CHV-R CHV

mean SE mean SE

CHV

Year 1 post restoration Year 2 post restoration

∗Indicates an alga species.



Table 5. (a) Percent composition of total catch of fish species for CHV and CHV-R during pre- and post-restoration sampling programs, all samplingmethods and (b) mean and maximum density of fish per beach seine pull.

(a)Pre-restoration Post-restoration Year One Post-restoration Year Two

Common Name Species Name CHV CHV-R CHV CHV-R CHV CHV-R

Atlantic silversidea Menidia menidia 10.0 74.1 6.5 94.0 4.6 72.7Banded Killifisha Fundulus heteroclitus 7.1 — — — — —Three-spine sticklebacka Gasterosteus aculeatus 11.4 0.8 1.4 — — —Nine-spine sticklebacka,b Pungitius pungitius — — 0.5 — 0.4 —Mummichoga Fundulus heteroclitus 55.7 24.9 91.5 6.0 94.9 26.6Tomcoda,b Microgadus tomcod 2.9 — — — — —American eela,b Anguilla rostrata 10.0 0.3 0.2 — 0.1 —Striped Bassc,b Morone saxatilis — — — — — —Brook trouta Salvelinus fontinalis 2.9 — — — — 0.8Total 100 100 100 100 100 100(b)Mean # fish per m2 per pull 0.02 0.83 0.07 0.11 1.28 0.11Maximum # fish per m2 per pull 0.03 1.48 0.19 0.18 3.56 0.18

aResident species.bMigratory species.cObserved being caught at mouth of system on the flood tide by local recreational fishermen (hook and line).

et al. 2007), likely due to the relatively elevated marsh plat-form and existing salt marsh vegetation. Rather, the returningfloodwaters reactivated the relict agricultural ditches whichprovided a conduit to the high marsh. Because this area wasalready waterlogged, it is not surprising that a large pannedeveloped and higher salinities were recorded as tidal watersevaporated. In addition, the increased tidal volume lead tomore flooding and created a hybrid network of channels incor-porating the ditches and natural tidal creeks. This system willlikely develop into the “superimposed” network type describedby Allen (2000).

The increased tidal channel density increased the proximityof segments of the marsh surface to a tidal channel (Lathropet al. 2000). Plant distribution is often related to tidal creeknetworks (e.g., Sanderson et al. 2000, 2001) and increaseddiversity has been recorded at other sites if drainage structuresare constructed and maintained (Wolters et al. 2005a). AtCHV, after an initial decline in species density immediatelyfollowing the reintroduction of tidal flow (likely due to theloss of upland species), colonization by native halophyticvegetation was rapid adjacent to the channel network and atthe upland boundary. With the reintroduction of tidal flow, theupland or freshwater plants were displaced and limited by theincreased salinity in these regions as found elsewhere (Crainet al. 2004).

Increasing the cross-sectional area of the culvert facilitatedmore effective tidal exchange, diminishing waterlogging insome areas of the marsh which is known to reduce vegetativecolonization (Haltiner et al. 1997; Crooks et al. 2002; Dausseet al. 2008), while inundating other areas leading to panneformation. Success was also dependent on the ability of themarsh surface to accrete vertically within the tidal frame(e.g., French 2006; Byers & Chmura 2007). Fundy marshestypically have high rates of sediment accretion (e.g., Chmura

et al. 2001; Ollerhead et al. 2003; van Proosdij et al. 2006b).Both CHV (pre- and post-restoration) and CHV-R recordedaccretion rates within the upper range of accretion ratesmeasured in the region. In addition, rates are still greater thancalculated rates of sea level rise for the region (0.55 cm/year;Shaw et al. 1998) and the presence of the causeway willprovide protection from the impact of storm waves. However,the rates recorded at CHV in both post-restoration years werethree times that of the reference site. We do not know ifthis difference is due to external variables such as suspendedsediment availability or position of the RSET stations withinthe marsh, which can significantly influence accretion rates(van Proosdij et al. 2006b). The increased tidal exchangemay also influence the amount of sediment deposition on themarsh surface by increasing the inundation frequency (e.g.,Cahoon & Reed 1995; French 2006; Byers & Chmura 2007).This increase was not observed at CHV post-restoration andalthough not statistically significant, there was a mean decreaseof 0.3 cm/year. There was considerable spatial variability insediment accretion across the marsh surface in all years whichis consistent with other studies (e.g., Allen 1992; van Proosdijet al. 2006a, 2006b).

The main way to assess success of restoration is by deter-mining similarity of vegetation cover and biomass betweenreference and restored marshes (e.g., Neckles et al. 2002; War-ren et al. 2002; Mitsch & Jorgensen 2004). Ideally, the refer-ence marsh should be similar in size, geometry, potential tidalrange, landscape position, adjacent land use, and water qual-ity (Neckles et al. 2002). However, the availability of undikedmarshes within the upper Bay is limited, reducing the numberof potential reference marshes. CHV-R marsh is comparableto CHV in most senses; however, it is smaller in size, thereforehas a smaller range of elevations. Thus, the two sites are posi-tioned differently within the tidal frame. The mean elevation



relative to CGVD28 datum of the CHV marsh platform is 5.49m (approximately 0.28 m less than mean high water [MHW])whereas CHV-R is 5.77 (= MHW). There is twice the rangeof elevation (2.4–7.4 m) at CHV versus CHV-R (4.2–6.6 m).This larger surface area and shallower upland slope will influ-ence the recolonization of the site and potentially the SR. Onceappropriate species colonize the study site, we might expectsignificant differences in overall species abundances (Onain-dia et al. 2001; Garbutt et al. 2006; Dausse et al. 2008): here adifference was detected just 2 years post-restoration. CHV hasa greater abundance of low marsh vegetation, characterized byS. alterniflora, whereas CHV-R has more high marsh or saltmeadow vegetation with Carex palacea and J. gerardii (blackgrass). The large vegetation growth range of S. alterniflora(Byers & Chmura 2007) will allow it to take advantage ofthe wide elevation range available at CHV. Furthermore, thissuggests that simple indicators such as SD may not be usefulindicators of restoration success, when restoration and refer-ence sites have environmental differences that select for plantcommunities with inherently different species pool sizes. Inthis case, low marsh communities are typically species poor,so CHV can be expected to have lower SD than CHV-R evenif the restoration of native salt marsh vegetation is success-ful and even though CHV has greater total species richness.Furthermore, certain species such as Plantago maritima havebeen found to thrive in the upper mid marsh which is regu-larly disturbed by ice (Chmura et al. 1997). Since CHV hasbeen isolated from the large ice blocks from the Bay whichtypically blanket undiked exposed marshes in the region dueto the presence of the causeway, the relative lack of Plantagomay be associated with lack of ice disturbance. Explicit mod-eling of the relationships between the biota and environmentalconditions may increase the utility of the single-reference siteapproach.

Faunal response is dependent on access to the shallowintertidal marsh surface and intertidal and subtidal creeks(Able et al. 2008). The response of nekton can be rapidwith an increase in density (Roman et al. 2002; Able et al.2008); however, SR can decrease (Raposa 2002). At CHV,there was a marked increase in the relative abundance of fishpre- and post-restoration, mostly due to the increased pannesize and creek network. This increased density was morepronounced in year two, which is consistent with findingsof other culvert replacement projects in the Gulf of Maine(Konisky et al. 2006). Consistently, more fish were caught atCHV compared to the reference site which may be attributedto the behavior of the dominant species. At CHV, Fundulusheteroclitus, a resident fish, dominated whereas at the referencesite Menidia menidia, a migrant species, occurred with thehighest frequency.

The monitoring program developed for this restorationproject was based largely on the GPAC protocol. The programexpanded on the protocols’ core indicators to include inver-tebrates (not reported in this paper) and winter conditions,modified a number of data collection methods (point inter-cept method for vegetation; sipper for interstitial pore watersalinity; capped/sealed wells and a breathing tube for depth

to water table; and beach seine and minnow traps for nek-ton), and increased the frequency of sampling events (nekton).Most of these modifications and additions were necessary inorder to accommodate the hydrological and climatic condi-tions experienced in the Bay of Fundy, issues of scale, andprogramming requirements. This modified monitoring pro-gram remains consistent enough with the GPAC protocolto facilitate comparisons with GPAC monitored sites, whilebeing more responsive to Bay of Fundy and other local site-specific conditions. Our results can provide insight into theecological interrelationships between biotic and abiotic vari-ables and contribute to the development of a set of referencemarsh conditions for future restoration projects in the Bayof Fundy.

Implications for Practice

• The availability of high-resolution elevation data suchas LiDAR early in the restoration process can signifi-cantly assist with effective placement of sampling sta-tions, particularly the RSETs and accurate tidal floodmodeling.

• Monitoring programs need to consider the spatial vari-ability of sedimentary processes such as sediment accre-tion within their sampling strategy.

• Simple indicators such as SR may not be useful indi-cators of restoration success, when restoration and ref-erence sites occupy different positions within the tidalframe or significant different ranges in elevation relativeto MHW.

• Culvert replacement projects can be an effective restora-tion technique in macro-tidal environments if the newculverts are sufficiently large to allow the majority ofspring tides to pass freely.

Acknowledgments

This restoration project would not have been possible with-out the financial and logistical assistance of the NSTIR, DFO,Ducks Unlimited Canada, local landowners/community, andthe Ecology Action Center. The Mount Allison Coastal Wet-lands Institute, Envirosphere Consultants, and R. Koniskyprovided assistance with laboratory analyses. G. Chmura isappreciated for assisting with RSET installations. G. Baker(Maritime Provinces Spatial Analysis Research Unit) providedinvaluable assistance with surveying and GIS analysis. T. Web-ster (COGS) generously provided the 2007 LiDAR survey.The Community Based Monitoring Network at Saint Mary’sUniversity is thanked for loaning water quality measuringequipment. Field data collection would not have been pos-sible without the assistance of E. O’Toole, A. Silver, and S.Townsend. Between 2002 and 2005, research was supportedfinancially by a wide range of sources (Bowron & Chiasson2006). Since 2005 funding has been provided by NSTIR andDFO-SCH.



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macro-tidal salt marsh ecosystem response to culvert - cbwes

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