1 Research and monitoring at Elkhorn Slough:improved conservation through understanding

2 CONSERVATION RESEARCHAt Elkhorn Slough Reserve

3 PLACE-BASED SCIENCE

4 LONG-TERM MONITORING

5 CITIZEN SCIENTISTS

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7 INFORMING MANAGEMENT

8 RESTORATION EXPERIMENTS

9 SALT MARSH ECOLOGY

10 SALT MARSH ECOLOGY Marsh values Marsh habitat requirementsThreats and what we can do about them Marshes and sea level rise

11 SALT MARSH VALUES Rare habitat type Unique plants Support for animalsImproved water quality Shoreline protection Carbon sequestration

12 Salt marshes are rare on this coast

13 Few estuaries in CaliforniaAt scale of whole coast, very few estuaries with more than a few hundred acres of habitat. Much less habitat than this picture suggests – dots are much too large for all except SF Bay Like archipelago of islands – not continuous habitat

14 UNIQUE PLANTS found in salt marshes

15 PICKLEWEED - SalicorniaDominant in low marsh

16 High marsh plants Dodder – Cuscuta on pickleweedSalt grass – Distichlis About 40 % of cover in ecotone is pickleweed, about 30% is upland plants

17 High marsh plants Atriplex – Spear scale Frankenia – alkali heathAbout 40 % of cover in ecotone is pickleweed, about 30% is upland plants Jaumea Grindelia – gum plant

18 BIRDS USE MARSH HABITAT

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23 MARSH PROVIDES REFUGE FOR MARINE MAMMALS

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25 WILDLIFE USE OF MARSH-UPLAND ECOTONE

26 MARSH DETRITUS SUPPORTS ESTUARINE FOOD WEBS

27 MARSHES CAN TRAP POLLUTED RUN-OFF

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30 SHORELINE PROECTION From wind waves & storms

31 “BLUE CARBON” Carbon sequestration

32 Measuring carbon sequestration

33 Measuring gas emissions

34 SALT MARSH VALUES Rare habitat type Unique plants Support for animalsImproved water quality Shoreline protection Carbon sequestration

35 SALT MARSH ECOLOGY Marsh values Marsh habitat requirementsThreats and what we can do about them Marshes and sea level rise

36 WHAT SALT MARSHES NEED Light Nutrients Moisture Soil

37 Light: generally not limiting

38 Nutrients: supplied by ocean and freshwater

39 Moisture: some freshwater, but mostly salt water

40 Moisture: CRITICAL!!! Too little tidal inundation:desiccation and competition from upland plants Too much tidal inundation: roots don’t get enough oxygen and plants drown

41 IT’S ALL ABOUT ELEVATION

42 Lower areas: drowned marsh Higher areas: healthy marsh

43 Lower areas: drowned marsh Higher areas: healthy marsh

44 Soil: CRITICAL!!! Horizontal processes:Banks retreat if sediment supply is to low

45 Marsh plain needs to build upward to track rising seasSoil: CRITICAL!!! Vertical processes: Marsh plain needs to build upward to track rising seas

46 From D. Cahoon

47 HORIZONTAL: EXPANSION OR RETREAT OF EDGE VERTICAL: UPWARD GROWTH OF MARSH PLAIN TO TRACK SEA LEVEL

48 MARSH DROWNING Due to insufficient external sediment supply or insufficient organic matter internally to build soil

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50 WHAT SALT MARSHES NEED Light: usually not an issueNutrients: not too much or little Moisture: not too much or little (elevation!) Soil: need to keep building up to track SLR

51 SALT MARSH ECOLOGY Marsh values Marsh habitat requirementsThreats and what we can do about them Marshes and sea level rise

52 THREATS TO SALT MARSHES and what we can do about themDiking Erosion Decreased freshwater inputs Eutrophication Trampling Invasions

53 DIKING/DRAINING MARSHES

54 LEGACY OF DIKING: SUBSIDENCE

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56 LEGACY OF DIKING: SUBSIDENCE

57 1870 2000 Sediment addition project From Van Dyke & Wasson 2005Minhoto restoration site is circled Sediment addition project From Van Dyke & Wasson 2005

58 SEDIMENT ADDITION To restore elevation and marsh

59 ARTIFICIAL HARBOR MOUTH

60 MARSH BANK EROSION

61 DECREASE TIDAL CURRENTSParsons Sill project

62 FRESHWATER INPUTS DECREASEDProblem because marshes need sediments that come with rivers, and marsh diversity requires some freshwater inputs. Estuary is where river meets the sea – but freshwater inputs have been greatly decreased to Elkhorn. Groundwater overdraft has led to the vanishing of artesian wells and freshwater all along margins. See loss of brackish plants, hear about from beth today Also rivers and creeks don’t flow freely into the estuary anymore.

63 EUTROPHICATION

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65 ALGAL WRACK AND MARSH

66 DECREASED PLANT HEALTH

67 VEGETATION RETREAT AND BANK EROSION marsh retreat rate (cm/yr)R2 = 0.62, P = marsh retreat rate (cm/yr) Wrack index

68 CATTLE TRAMPLING Cattle grazing tool used by land managers for adjacent grasslands, increases native forbs At similar densities, not beneficial for marsh and ecotone (we had about 1 cow/hectare for this study)

69 CATTLE TRAMPLING Fencing prevents harm

70 HUMAN TRAILS

71 BOARDWALKS PROTECT MARSH

72 NON-NATIVE PLANT INVASIONSpoison hemlock ice plant MARSH MARSH

73 ICE PLANT REMOVAL

74 THREATS TO SALT MARSHES and what we can do about themDiking>>>restore tides, add sediment Erosion>>>reduce currents Decreased freshwater inputs>>>restore some Eutrophication>>>decrease nutrients Trampling>>>limit access Invasions>>>prevent and restore

75 SALT MARSH ECOLOGY Marsh values Marsh habitat requirementsThreats and what we can do about them Marshes and sea level rise

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77 GREENHOUSE GAS INCREASESSharp climb in past 100 yrs

78 SEA LEVEL RISE High uncertainty, but major increases projected

79 WARMING CAUSES SEA LEVEL RISE

80 SEA LEVEL RISE PROJECTIONS

81 KING TIDES OFFER PREVIEW

82 MONTEREY TIDE STATION Sea level rise still moderate

83 MONTEREY TIDE STATION Short term high water levels

84 Dieback of lower edge of marsh: High water levels during El Nino

85 RESILIENCE TO SEA LEVEL RISEExisting marshes tracking SLR; marsh survives in current area Migration of marshes upward; marshes occupy new areas

86 Coastal Marsh MHW intertidal MLW

87 Rapid sea level rise = marsh drowningMHW intertidal MLW SEA LEVEL RISE If a tidal marsh has an adequate sediment supply, it responds to sea level rise by accumulating sediments. Examples: 1. South San Francisco Bay and groundwater overdraft 2. sediment accumulation data from the past decades in the Mid-Atlantic (sediment accumulation appears to track tide cycles)

88 Adequate sediment or slow SLR = survivalMHW intertidal MLW organic sediment If a tidal marsh has an adequate sediment supply, it responds to sea level rise by accumulating sediments. Examples: 1. South San Francisco Bay and groundwater overdraft 2. sediment accumulation data from the past decades in the Mid-Atlantic (sediment accumulation appears to track tide cycles)

89 RESILIENCE TO SEA LEVEL RISE Factors that help existing marshesMarsh elevation>>>high marshes safer Tidal range>>>larger range provides buffer Elevation change>>>rising marshes safer Sediment supply>>>more helps track SLR Eutrophication>>>can cause subsidence Groundwater overdraft>>>ditto

90 Surveying elevation of marshes

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92 Measuring marsh elevation change

93 Measuring sea level

94 Elkhorn Slough resilience:Sea level rise: +1.4 mm/yr (and increasing) Marsh accretion: mm/yr Marsh subsidence: mm/yr Net elevation gain: +0.9 mm/yr Not enough….

95 How resilient are US marshes in the face of sea level rise? Analysis across the National Estuarine Reserves LDD Legend Number of metrics (of 10) that show high risk 1 2 3 4 >5

96 RESILIENCE TO SEA LEVEL RISEExisting marshes tracking SLR; marsh survives in current area Migration of marshes upward; marshes occupy new areas

97 BATHTUB RING Narrow band of marsh may result from upward migration on steep slopes

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99 SEA LEVE RISE PROJECTIONSNOAA’S SEA LEVEL RISE VIEWER https://coast.noaa.gov/slr/

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101 HOW CAN WE SUPPORT MARSH RESILIENCE?

102 SUPPLY SEDIMENT

103 DECREASE OTHER STRESSORS

104 FACILITATE MIGRATION

105 UNDERSTAND, APPRECIATE, CONSERVE AND RESTORE OUR SALT MARSHES!