Macro-Tidal Salt Marsh Ecosystem Response to Culvert Expansion

Macro-Tidal Salt Marsh EcosystemResponse to Culvert ExpansionBowron, T 1 ., N. Neatt 1 , D. van Proosdij 2 , J.Lundholm 3 and J. Graham 11CB Wetlands and Environmental Specialists Inc.2Department of Geography, Saint Mary’s University3Department of Biology, Saint Mary’s UniversityRAE 2010Bowron, T., Neatt, N., van Proosdij, D., Lundholm, J., Grahams, J., 2009. Macro-tidal SaltMarsh Ecosystem Response to Culvert Expansion. Restoration Ecology.

Halifax, Nova Scotia (Canada)Full service coastal wetland restoration providerPartnership with Saint Mary’s University (Halifax)Emphasis on research & monitoringStrong ties with government & NGO communitywww.cbwes.com

•Cheverie Creek (2005)-5 yr post-restoration monitoring•Walton River (2005)–5 yr post-restoration monitoring•Smith Gut (2006)–4 yr post-restoration monitoring•Lawrencetown (2007)–3 yr post-restoration monitoring•St. Croix River (2009)•1 yr post-restoration monitoring•Cogmagun River (2009)-1 yr post-restoration monitoringSalt Marsh Restoration in NSFederal & Provincial compensationprojectsPartners:Dept. of TransportationFisheries & Oceans CanadaDept. of AgricultureSaint Mary’s UniversityDucks Unlimited CanadaEcology Action CentreLocal Communities

~62% of provincial saltmarshes~80% for the Bay of Fundy~65% of rivers partially tocompletely restricted

Cheverie Creek Salt Marsh Restoration Project•Eliminate tidalrestriction•Improve existingwetland conditions•Increase amountof salt marsh•Improve fishpassage & habitatconditions

6 Year Monitoring Program•Reference site•GPAC regionalmonitoringprotocol;CAMP; RCA•Hydrology•Soils &sediment•Vegetation•Fish•Invertebrates•Birds (DUC)

Cheverie paper – pre & 2 years post monitoring

Hydrology• DEM•Tidal signal & hydroperiod• Depth to groundwater• eliminated tidal restriction (tides

Soils & SedimentsInterstitial Pore Water Salinity• shallow & deep samples•Sipper & refractometerSoil Characteristics• OM, bulk density, water content, grain size•Sediment coresChanges in marsh surface elevation•Surface & subsurface process•Rod Sediment Elevation Tables (RSET)•Marker horizons•Sediment plates

Salinity•increase in levels & range•seasonal trend•levels significantly higher than @ referenceSoil Characteristics• soil types & patterns typical of Bay of Fundysalt marshBulk densityOrganic matterGrain size

Changes in marsh surface elevation• RSETs & MH - greatest change (increase) in surface elevation recorded post year 1(deposition & subsurface processes)• signif. diff. b/w sites (CHV 1.22 ± 0.68 cm/yr vrs. BAS 0.26 ± 0.03 cm/yrBy 2009 no significantdifference between sites(repeated measuresANOVA; F 1,3 = 0.711;P=0.437)Subsurface processes &changes in vegetationcommunity structure

Vegetation•26 transects & 119 sample plots (1 m 2 ) (study)•8 transects & 27 plots (reference)•Point & Line Intercept sample methods•Sampled annually - August• rapid decrease in non-halophytic vegetation• Increase in halophytic species• in species richness followed by an to a level approaching that of reference•Increase in area of marsh

Nekton (fish)•30 m beach seine•minnow traps•Fyke net•3 sampling events (spring tides); 1 – 3 pulls per eventa) Percent composition of total catch of fish species for CHV and CHV-R duringpre- and post-restoration sampling programs, all sampling methods and b) mean andmaximum density of fish per beach seine pull.•Year 2 saw greatest number of fish at CHV

Now be honest…Do these waders make me look fat?

Discussion & Conclusions• 8-fold Increase in area flooded, significantly increased the areaavailable for fish and habitat development.•Primary variables driving the ecosystem response are hydrology andsurface topography/elevation• Vegetation recovery can be rapid (2 years) when sources for recolonizationare nearby and shifts in abiotic conditions result in mortalityof terrestrial vegetation.•The availability of high resolution elevation data such as LiDAR & lowaltitude aerial photography can signification assist with restorationdesign & monitoring (flood plain modeling)

Discussion & Conclusions cont’d …• Pre & post restoration monitoring is critical. GPAC Protocol, whenmodified to be more responsive to local conditions, can be an effectivetool for determining project success•Culvert replacement & dyke breaching projects can be an effectiverestoration technique in macro-tidal environments as long as they areproperly designed – new culverts & breaches are sufficiently sized toallow the majority of spring tides to pass freely

AcknowledgementsSMU - MP_SpARC, CBEMNMt. Allison Wetland Research CenterAcadia Center Estuarine ResearchEnvirosphere Consultants Ltd.NSERCDr. Bob Pett (NSTIR)Ducks Unlimited CanadaFisheries & Oceans CanadaEcology Action CentreNS Dept. of Natural ResourcesNS Dept. of AgricultureGoMC/GPACTony Bowron902-431-5772tony.bowron@gmail.comwww.cbwes.comBowron, T., Neatt, N., van Proosdij, D., Lundholm, J., Grahams, J., 2009. MacrotidalSalt Marsh Ecosystem Response to Culvert Expansion. Restoration Ecology