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Tidal Wetlands in the Delaware Estuary: Projected Effects of Salinity and Sea Level Rise and Potential Adaptation Strategies

Danielle KreegerScience DirectorPartnership for the Delaware Estuary

Importance of Tidal Wetlands

Tidal Wetlands

A Signature Trait of System

•Near Contiguous Band

•Diverse: Freshwater Tidal MarshesBrackish MarshesSalt Marshes

Tidal Wetlands

A Signature Trait

Ecological Values:

Structuralhabitat for fish and wildlifenurseries for imperiled taxa

Functionalfood webwater qualityflood protection

+ Many other supporting services

Milenium Ecosystem Assessment

1º Service2º Service 3º Service 4º Service

Provisioning

FoodFisheries Support

Algae and invertebrate production

Genetic Materials Phragmites control research

Biochemical Products Research in Antifungal Agents

Fiber and Fuel Cellulose stock

Regulating

Sequestration Carbon

Carbon Caps,

mitigation

Sediment StabilizationErosion control

Meet TMDLs for

sedimentStorm Protection/ Wave Attenuation/

Flood ProtectionProtect Property Values and

infrastructure

Gas RegulationCarbon Sequestration

Oxygen production

Water Quality Sequestration, Filtering TMDLs: Nutrients,

Pollutants

Cultural/ Spiritual

Human Well Being

Recreation Bird watching, hunting, boating

Spiritual and Inspirational Native American Uses

Educational

University reasearch & school

projects/trips

Aesthetic Value

Landscape pictures, paintings,

open space

Supporting

Habitat Wildlife, shellfish, insects

Biodiversity Maintain Plant Communities

Production Primary Production

Water Cycling/Hydrologic Regime

Nutrient Cycling/Biogeochemical

Processes

Maintain trophic cycles, soil

building

Wetland Ecosystem Services

Valuation of New

Jersey’s Natural

Capital and

Ecosystem Services

New Jersey Department of

Environmental Protection

Slide from Bill Mates, NJDEP 6Kreeger

Tidal Wetlands

A Signature Trait of the Delaware Estuary System

Ecological Values:

Structuralhabitat for fish and wildlifenurseries for imperiled taxa

Functionalfood webwater qualityflood protection

Concerns:

Degradation

Degradation

Moderately

Stressed

48%

Severely

Stressed

35%

Minimally

or Not

Stressed

17%

Tidal Wetlands

Ecological Values:

Structuralhabitat

Functionalfood webwater qualityflood protection

Concerns:Degradation

Conversion & Loss

Freshwater Tidal Wetland Acreage

Estimated

< 5% remains

Tidal Wetlands

Ecological Values:

Structuralhabitat

Functionalfood webwater qualityflood protection

Concerns:DegradationConversion & Loss

Sea level riseSalinity rise

Canary Creek Marsh, DE

1992

2006

Courtesy J. Gebert, ACOE

Courtesy D. Bushek, Rutgers

ShorelineErosion

Tidal Wetlands

Ecological Values:

Structuralhabitat

Functionalfood webwater qualityflood protection

Storms

Concerns:DegradationConversion & LossSea Level Rise

Living Shorelines 2008

Tidal Wetlands

Concerns:Degradation Conversion and LossSea Level RiseStorms

Sediment budget

1. Likely Physical Changes

2. Example Effects on Resources

Temp

Salinity Sea Level Rise

Marshes Bivalves

Storms

Climate Change in the Delaware Estuary

DK 17

Drinking Water

Climate

Adaptation

Planning

Tidal Marshes Bivalve Shellfish

ID

Vulnerabilities

Ecological

Valuation

Adaptation

Options

Recommendations

and Reporting

Case Studies

Drinking Water

18Kreeger

Tidal Wetland Vulnerability?

Freshwater Tidal Marshes

• Salinity Rise Causes Conversion to Brackish• Barriers to Landward Migration• Others: Tidal Range, Seasonal Drying/Wetting

Salt Marshes

• Sea Level Rise, Subsidence and Sediment Deficits Lead to Drowning

• Storms and Wind Wave Erosion• Barriers to Landward Migration• Others: Seasonal Wetting/Drying, Invasives

Slide adapted from Michael Craghan, Rutgers

Tidal marshes need to move:

1) horizontally(landward)

and/or

2) vertically(to keep pace)

Can they do it?

Where?

DK 20

Tidal Wetlands Adaptation PlanningGoal: Maximize long-term ecosystem health and resiliency

Wetland Tough Choices• Where will wetlands will be

converted to open water?• Where can we save them ?• Where is strategic retreat

the best option?DK 21

Projecting the Fate of Tidal Wetlands and Their Ecosystem

Services Using SLAMM Modeling - Industrial Economics

Areas for Model Improvement

• Erosion/Accretion Rates

• Better Vegetation Classifications

• Marsh Drowning Mechanisms

2000 2100

Added Complexity

•Dredging

•Ecological Flows

•Withdrawals

•LNG Terminal

•Horseshoe Crabs, Red Knots

•Inundation, SLR

•Emerging Pollutants

•Spills, NRDA

•Land Use Change

So What Can We Do?

What Can We Do? 1. Preserve Resiliency

Protect and Conserve (CCMP)

What Can We Do? 2. Monitor & Study

MACWA

The Mid-Atlantic Coastal Wetland

Assessment

What Can We Do? 3. Maintain, Enhance, Restore..

Shovel Ready Projects !!

…But Smartly

Regional Restoration for

Future Sustainability/

Changes in Wetland FunctionNatural versus Restored

time

Function

Reference Wetland Condition

Restored Wetlands

Existing Wetlands

Slide from Amy Jacobs (DE DNREC)

Principle: “Restore” for the Future

• Forecast future sustainable states• Smart “restoration” = climate adaptation

DK 31

• Shift policy and management paradigms

• Reduce wave energy

• Trap silt

• Reduce bank erosion

• Protect salt marsh

Shellfish as Natural Breakwaters

Slide from Dave Bushek, Rutgers

Delaware Estuary Living Shoreline Initiative

Geukensia demissa

Salt Marshes

Ecosystem Engineers

Mussel –SpartinaMutualism

Kathy Klein

Ribbed mussels as an alternative target restoration species

– Not commercially important, not eaten– No conflict between restoring shellfish and protecting human health

and industry

– Mussels provide ecological benefits like oysters– Filtration, habitat enrichment

– Biodeposition facilitates cord grass production and levee formation

– Shoreline stabilization

– Could combine with restoration of marshes and nearshore oyster reefs for greater impact, in some areas

Living Shorelines

Importance of Shellfish to

the Delaware Estuary

Watershed

Examples

Log + Log + Shell Bags

Site D - Lower Energy

Goal: Maximize Future Tidal Wetland Natural Capital

40Kreeger

Principles:1. Base natural capital on functional acreage, not just acreage

enhancing condition of existing wetlands may yield greater functional acreage in the long term compared to traditional restoration/creation (acreage focus)

2. Strive for high resilience and low vulnerabilityinvest in wetlands that are most sustainable

3. Consider Ways to Mitigate Watershed Stressorsbroad impacts (sediment deficits, nutrient imbalances) may be bestaddressed with management and policy decision-making

Carbon Sequestration Uplift

Preservation and Enhancement

(e.g. Living Shorelines)

Traditional Restoration,

Creation

Landward Migration

Investments

41Kreeger

CarbonSeq.

vs

acreage

condition function

How much CS per $in 1 year?in 30 years?

- End -

e.g., Carbon Sequestration

Some Literature

Temperate wetlands accumulate 1.42 tons C ha-1 yr-1

Wetlands represent the largest component of the terrestrial biological C pool

Average soil organic carbon density (Denmark)Wetlands: 35.6 kg m−2

Forests: 16.9 kg m−2

Agricultural areas: 14.0 kg m−2

Conversion of agricultural lands to wetlands can enhance C sequestration

In contrast to other wetlands, tidal salt marshes release negligible amounts of greenhouse gases and store more carbon per unit area