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Life on a sandy edge: conserving
beach ecosystems in the face of rising
seas
Jenny DuganMarine Science InstituteUniversity of California
Santa Barbara
Beaches = ~75% of open coast
• Recreation
• Coastal economy
• Aesthetics
• Cultural identity
Iconic Assets
Beach ecosystems are more than sand
Beaches as Ecosystems
Beach Ecosystem Functions & Services
• Water filtration• Nutrient cycling
Water filtration
Nutrient cycling
Beaches can absorb wave energy
Beach Ecosystem Functions & Services
Accumulate & Store Sand
Linked Dunes & Beaches as resilient buffers to climatic forcing
C. Bowdish
High Biodiversity & Rich Prey Resources for Birds & Fish
Beach Fisheries:
Pismo Clams
Surf Fishing
California Grunion
Grunion.orgJ. Flannery
A Special Fish
Critical Habitat & Prey for Shorebirds
Western Snowy Plover young chick with prey
C. Bowdish
Northern Elephant Seals
Beach EcosystemsHighly mobile animals and no attached plants
Unconsolidated sedimentsExtremely dynamic zonation
Variation in elevation & widthStrong influence of: – Wave exposure– Sediment supply– Habitat alteration
Beach Management: Grooming
S. Cal. Groomed Beaches = ~45% (>100 miles)
Post Hurricane Beach Filling: Galveston, Texas
Goleta Beach fill & sediment plume February 2011
Sandy Beaches
• Animals adapted to frequent disturbance of sand by waves & wind
• Rapid recovery from impacts assumed• Ecological monitoring absent
Coastal Squeeze Development Sea level rise
The Last BeachPilkey &
Cooper 2014
Predicted loss of up to 67% of beaches by 2100Vitousek et al 2017
Coastal Ecosystem Vulnerability Assessment:
Sandy Beaches Santa Barbara County
Jenny Dugan, Dave Hubbard, Alex Snyder*, Kyle Emery, Patrick Barnard*, Dan Hoover*
Marine Science Institute, UC Santa BarbaraUSGS Pacific Coastal & Marine Science Center, Santa Cruz*
Objectives:
• Integrate ecology & geomorphology of beaches
• Project ecosystem responses• Assess vulnerability of sandy beach
ecosystems to climate change
Upper/”dry”
High Tide
Strand HTS
Beach
Zones
Mid/damp
Low/wet
Water Table
Outcrop WTO
Upper beach zones
• Nesting Habitat• Ecotone - coastal
strand vegetation• Wrack deposition &
processing• 40% of biodiversity
• Buffer zone for mobile intertidal life during storms
ApproachGeo-referenced beach profiles,
widths & coastal
processes
Projected responses of beach ecosystem features
CoSMoS 3.0 Runup &
Shoreline Change
Ecological Framework & Validation
Total Water Level (TWL) as an Ecological Datum
• TWL = Predicted tide level + wave runup (incl wave setup)
• Approximation of high tide strand line (HTS),= lower bound upper intertidal zone
• Key beach taxa and functions e.g. talitrid amphipods, wrack, sand accumulation
• Critical boundary for beach nesting wildlife e.g. snowy plovers, sea turtles & grunion
• Annual peak TWL sets lower edge of coastal strand zone
Vulnerability of Beaches to Climate Change
Landward boundary determines scope for migration of ecosystem
– Bluffs
– Dunes
– Armoring and infrastructure
– Habitat alteration
Bluff-Backed Beaches85% loss of
upper beach zone
Armored Beaches99% loss of upper zone
Coastal SqueezeArroyo Quemado Seawall
•Upper beach zones already lost on many armored beaches
Dune-backed Beaches~ 60% loss of upper zone at 50 cm SLR
15% remains at 150 cm
Landward intertidal boundary moves inland:Erosion of dunes - Fall 2014
• Dune habitat area declines as beach retreats
Groomed Beaches 50% loss of upper zone at 50 cm SLR
< 5% remains at 150 cm
Beach Ecosystems Highly Vulnerable Tipping Point ~50 cm SLR
CoSMoS 3.0 Projections
Groomed Beaches
• Ecosystems degraded by grooming• Potential for restoration & conservation
Beaches as wetlands
Conserving Sandy Beach Ecosystems
• Manage more beaches for biodiversity & ecological function
• Restore resiliency: provide space for beaches to move
• Minimize impacts and interventions
• Maintain/enhance connectivity with land & sea
• Identify and restore beaches with scope for retreat
Made possible by support from:
• NOAA Climate Program Office• Sea Grant (National Office)• Santa Barbara Coastal LTER• National Science Foundation• United States Geological Survey• UCSB Coastal Fund
Beach Ecosystem Vulnerability Assessment
Questions?
Thank you!
Example
Bluff-backed beach
Arroyo Burro
SLR = 0 cm
SLR = 50 cm
SLR = 100 cm
SLR = 150 cm
SLR = 200 cm
SLR = 500 cm
•90% loss of upper beach zone with 50 cm SLR
Upp
er B
each
Zon
e W
idth
(m)
West East
CoSMoS 3.0 Model projectionsUpper Beach Zone
Armored beachSanta Claus Lane
•99% loss of upper beach zone with 50 cm SLR
Upp
er B
each
Zon
e W
idth
(m)
SLR = 0 cm
SLR = 50 cm
SLR = 100 cm
SLR = 150 cm
SLR = 200 cm
SLR = 500 cm
West East
CoSMoS 3.0 Model projectionsUpper Beach Zone
Dune-backed Beach
Sands/Ellwood
Upp
er B
each
Zon
e W
idth
(m)
SLR = 0 cm
SLR = 50 cm
SLR = 100 cm
SLR = 150 cm
SLR = 200 cm
SLR = 500 cm
West East
CoSMoS 3.0 Model projectionsUpper Beach Zone
•>60% loss of upper beach zone with 50 cm SLR•Much reduced upper beach zone, 9%, remains with 200 cm SLR
Groomed/Filled East Beach
•50% loss of upper beach zone with 50 cm SLR•Greatly reduced upper beach zone <5 m width persists with 150 cm SLR
Upp
er B
each
Zon
e W
idth
(m)
SLR = 0 cm
SLR = 50 cm
SLR = 100 cm
SLR = 150 cm
SLR = 200 cm
SLR = 500 cm
West East
CoSMoS 3.0 Model projectionsUpper Beach Zone
Key Axes of Influence