Wetland Restoration

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Wetland Restoration
Definitions Motivations Types and
Approaches Costs Design Issues Ecological Theory
Monitoring Case Studies Southern California
Restoration Projects
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Wetland Restoration
Restoration - Returning a degraded wetland or
former wetland to a pre-existing condition or as
close to that condition as possible. Creation -
Converting a non-wetland (either dry land or
unvegetated water) to a wetland. Enhancement -
Increasing one or more of the functions
performed by an existing wetland beyond what
currently or previously existed in the wetland.
There may be a decrease in other
functions. Mitigation - the actual restoration,
creation or enhancement of wetlands to
compensate for permitted wetland losses.
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Restoration/Creation Motivation

• US - No Net Wetland Loss Policy
• Treating Urban Runoff
• (excess nutrients, contaminants)
• Excess sedimentation
• Mitigation - To compensate for loss
• on site or off site
• in kind or out of kind
• banking
• Improve habitat quality and function, expand
  existing wetlands

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Forms of Restoration

• Grading of upland to intertidal levels (marsh,
  mangrove, tidal flat)
• Hydrological improvement (e.g., dredging, opening
  lagoons to flushing)
• Creation of habitat via dredge spoil islands
  (often planted)
• Planting unvegetated bottom with seagrass or
  marsh grass
• Amending soils with nutrients or organic matter
  (e.g., peat, straw, alfalfa, kelp)

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Restoration Costs - Louisiana examples
Approach Restoration Rate Size (ha) /ha Crevass
e Splays 1.1 10-300 48 Agric. Impoundments
1 300-7,000 1 Backfilled canals 1.5 1-50 1,000
Spoil Bank Rest. 2.5 10-1000 10 Terracing 5 10-
100 4,686 Dredge Mat. wetlands
gt50 lt1-100 0-23,600 Excavated
wetlands gt20 1-100 44,600 Thin Layer Placement
? 1-100 ??? FROM Turner and Streever 2002
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Who Pays?

• Power companies
• Transit Authorities
• Port Authorities
• Cities, Counties, States (taxpayers)
• Federal Government

Attempts to value wetlands LA salt marshes
valued at 9-17K per acre (must be per year).
Kendall Frost property 1.6 million for 2.1 acres
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Restoration Design Issues

• Site limitations - in So. Calif. available space
  is limiting, especially for
• local mitigation. Land is expensive!
• 2. To plant or not. What to plant, Where to get
  plants from (genetic concerns)
• Rarely are animals introduced - it is assumed
  that if you build it, they will come.
• 3. Hydrology, creek design, edge habitat,
• 4. Ratios of low, mid, upper, transitional marsh
• Seagrass vs unvegetated
• 5. Need for upland and ocean end management as
  well.
• Difficult to create and manage a coastal wetland
  in isolation without control over
• adjacent habitats.
• 6. Incorporating science into the restoration
  effort (e.g., Mission Bay)
• Major limiting factor is knowledge about what
  maximizes productivity and health
• Prior history of habitat existence important.
• Failure greater where there was no historical
  wetland

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DANGER
THAT ABILITY TO MITIGATE WILL ENCOURAGE
DESTRUCTION OF NATURAL HABITAT To avoid this,
we must have strict rules about loss of natural
wetlands.
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Monitoring

• Comparison to reference sites
• Frequency and duration - 5 years is not enough!
• Adaptive monitoring - change in response to
  events
• Community involvement
• What and how to monitor.
• Plants, animals, fishes, birds,
• Increasing emphasis on function
• Should science be part of monitoring?
• Need success criteria
• Comparison to less disturbed reference wetlands
• Often these aren't available in urbanized
  estuaries.
• Standardized methods? - usually not.

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Structure vs Function

• Difference between structure (who and how many
  are there)
• and function (ecological processes productivity,
  nutrient cycling,
• trophic support, resistance to invasion).
• Success criteria try to incorporate both but it
  is difficult.
• Structure is easier to measure.
• Sometimes endangered species or top carnivores
  drive criteria.
• More often plants dominate.

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Restoration Approaches
Passive - Removing source of problem Benefits
- low cost, compatibility with surrounding
landscape Examples Removing dikes,
ponds Removing grazing cattle Active - Physical
intervention Recontouring to achieve desired
topography and elevation Changing water flow
(e.g., inlet opening, channel construction
wiers, culverts) Planting and
seeding Non-native species control Soil
enhancement
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Incorporating Research/Experiments(mensurative
or manipulative)
Allows for development and testing
of restoration theory (Zeder 2005) Allows for
Adaptive Restoration modification of
restoration plan over time.
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Relevant Ecological Theory and Practice(Zedler
2005)

• Controls and Reference sites (natural
  variability)
• Biodiversity and Ecosystem Function
• (productivity, invasion resistance, nutrient
  cycling)
• (critical function species)
• Eutrophication
• effects on wetland diversity
• wetlands as the cure
• Island Biogeography/Connectivity
• (applications may differ among organisms)

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Ecological Theory (cont)

• Succession
• primary succession
• microbial feedbacks
• plant-animal interactions
• Facilitation
• Competition
• Predator-Prey Interactions (e.g., birds in So.
  San Diego Bay)
• Food Web Theory/ Trophic Cascades
• Assembly Rules
• Extended phenotypes/ Hybridization genetic
  influences
• Invasion Biology how to prevent establishment
  of invasives
• Resilience

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Port Marsh, North Carolina

• Created in 1990 by grading 2.2 acre dry dredge
  spoil to sea level.
• Planting with S. alterniflora. 9 culm/m2.
• Isolated from adjacent natural system by
  oysters, sediment and
• land plants.
• 3 blocks each with OM treatments applied to 2 x 7
  m plots.

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• Spartina grew rapidly.
• By 1993 there were no differences in biomass
  or stem densities
• in created and adjacent natural marsh.
• By 1994 biomass and stem densities in
  created marsh were
• 2x those of natural marsh.
• Despite rapid vascular plant recovery, the
  animals did not
• recover as quickly.
• After 27 mo some epifauna like mussels, oysters,
  mud crabs
• and littorine snails never appeared.

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Natural Unplanted Planted
Density
Spp. number
Port Marsh Infauna
Levin et al. 1996, MEPS
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Organic Amendments - Straw Alfalfa, Peat, plus
inorganic N. Initially killed plants and
reduced animal densities in NC (figure) .
Effects disappeared after 6 months, except for
straw treatments which exhibited reduced
densities for several years.
Macrofaunal density
Natural
Levin et al. 1997
Straw
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Macrofauna Succession

• Early opportunistic polychaetes
• (S. benedicti, Capitella, Polydora cornuta)
• Total macro density and species richness reached
  ambient (natural) levels at 6 mo.
• For first few years these and turbellarians
• were 75-95 of fauna
• At year 4 diversity higher but sediments remained
  different. No oligochaetes
• (coarser and lower OM in created marsh).

Levin et al. 1996, MEPS
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BUT species composition and functional groups did
not resemble natural marsh. Species without
dispersive stages (lecithotrophs/direct
developers) were slow to recover. Species with
dispersive stages (planktotrophs, swimmers)
overshot natural marsh
Natural Unplanted Planted
Planktotrophs
Direct Developers
Levin et al. 1996, MEPS
Lecithotrophs
Swimmers
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Natural Unplanted Planted
Surface Feeders
Oligochaetes were 50 of natural marsh fauna but
rare in the created marsh. Instead of a
subsurface deposit- feeder dominated fauna, the
created marsh was surface-feeder dominated.
Subsurface Feeders
Carnivores Omnivores
Levin et al. 1996, MEPS
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Recommendationsfrom Port Marsh study

• Connections with natural marsh/direct contact
  desirable
• Seeding animals may help, particularly for
  non-dispersers
• Attention to sediment properties (Grain size, OM)

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Craft Sacco 2003 Marsh restoration sites in
North Carolina
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Dills Creek
Created from upland pine forest
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Craft Sacco 2003 Surface feeders recover more
quickly than subsurface feeders.
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Craft Sacco 2003 MEPS Soil organic matter is
correlated with faunal density.
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Craft Sacco 2003 MEPS Created marshes may
overshoot natural ones.
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Southern California has 29 small embayments,
many with restoration projects planned or in
progress.
Zedler 1996
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Southern California Restoration ProjectsZedler
1996 - Ecol. Applications
Goleta Slough Remove obstructions to increase
tidal flows Carpinteria Marsh Excavate adjacent
site to increase area of tidal influence Balona
Wetland Open tide gates, increase tidal flow to
salt marsh Los Cerritos Wetland Increase access
to tidal flow in diked marshes Seal Beach
NWR Maintain tidal systems Bolsa Chica
Wetland Entrance tidal access to diked marshes
and mudflats Santa Margarita Estuary Dredge mouth
to extend periods of tidal influence Agua
Hedionda Lagoon Dredge mouth periodically to
sustain tidal influence Batiquitos Lagoon Dredge
mouth to change nontidal to tidal wetland San
Elijo Lagoon Dredge mouth to change nontidal to
tidal wetland San Dieguito lagoon Restored
wetland, enhance hope water areas, open mouth Los
Penasquitos Lagoon Dredge mouth to extend periods
of tidal influence Famosa Slough Enlarge
culverts to extend tidal influence Mission
Bay Dredge to create salt marsh Sweetwater
Marsh/So. Bay Excavate to create salt marsh/
Restore salt ponds Tijuana Estuary Excavate
upland to create salt marsh and tidal creeks
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Diversity is lower in lagoons that close
periodically.
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Zedler
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Zedler
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Macrofaunal Recovery - Salicornia marshes in
southern California
Talley Levin 1999
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Talley Levin 1999 Comparison of macrofaunal
composition in created and natural Salicornia
marshes
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Crown Point Mitigation Site, Mission Bay CA
Crown Point Mitigation Site, Mission Bay
Natural marsh
Graded and Restored to tidal flushing Dec. 1995
Created marsh
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Southern California - Crown Point Mitigation Site
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Crown Point Mitigation Site - Opened Dec. 1995
January 1996 (1 mo)
April 1998 (2 yr 4 mo)
Summer 2001 ( 5 yr 6 mo)
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Belowground Plant Detritus
Created (CPMS)
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Natural NWP)
3
Detritus (grams/18 cm2 core)
2
1
0
1996
1997
1998
1999
2001
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Levin Talley 2002
CPMS created average NWP natural average
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Levin Talley 2002
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------------------April------------------
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Mission Bay Macrofauna-Natural marsh
100
Insect
75
Polychaete
Mollusc
Peracarid
Nadid
50
Percent
Enchytraeid
Tubificid
Other
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0
1996
1997
1998
1999
2001
2001 (fall)
-----------------April------------------
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Created Natural Marsh
During the El Niño (98) the created and
natural marsh macrofauna were most similar
Levin Talley 2002 MDS indicating similarity of
macrofaunal composition.
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Tijuana Friendship Marsh
20 acres Opened in Feb. 2000 Constructed creeks,
Planted Spartina
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3 tidal creeks kelp amendments 2 plant densities
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Friendship Marsh Macrofauna
data from Moseman et al.
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Upcoming Restoration Projects

• San Dieguito Lagoon
• Permanent inlet opening
• Wetland grading, planting
• Tijuana Estuary
• 380 additional acres salt marsh
• San Elijo and Los Penasquitos Lagoon
• Episodic inlet openings
• South San Diego Bay Wildlife Refuge Pond
  conversion to tidal habitat
• Grading of fill
• Kendall Frost - ?
• Frost Property,
• Campland Acquisition - 2017?