Implementation follows a tiered approach. Tier I (table cells highlighted in grey): minimal monitoring of hydrology, soils and sediments, and vegetation Core Variables that should occur at all sites. Tier II: recommended monitoring that includes Tier I plus one faunal indicator (nekton, birds, or invertebrates) wherever possible. Tier III: intensive monitoring of all Core Variables, which should occur at a relatively small number of sites. Tier IV: research to diagnose cause-effect relationships includes all Core and Additional Variables. Printer-friendly versions of the Gulf of Maine Salt Marsh Monitoring Protocol: Word (80 KB) • PDF (104 KB)
| Grey table cells: | Tier 1 Core Variables, necessary for minimal monitoring. |
Core Variables |
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Variable name |
Description |
Sampling method |
Annual sampling frequency (before and five consecutive years after restoration, except as noted) |
Hydrology |
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| Hydrology signal | Pattern of water-level change with respect to a reference point | Continuous water-level recorders upstream (impacted/restored) and downstream (reference) for non-ditchplug projects |
For tides, one 2-4 week period of operation (before and 1 year after restoration) |
| Elevation | Marsh-surface elevation at contour intervals of 15 centimeters or less | Contour map |
For all projects, once before (plus 1 year after restoration for excavation projects only) |
Soils and Sediments |
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| Pore-water salinity | Parts dissolved salts per thousand (also referenced to Practical Salinity Scale) of soil water collected from 5-25 centimeter depths | Groundwater wells, soil cores, or sippers at impacted/restored and reference sites | For all projects, at low tide between early (April/May) and mid- (July/August) growing seasons, including spring/neap tides (6 times per year) |
Vegetation |
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| Composition | Identity of all plant species occurring per square meter | Permanent or temporary plots (0.5-1 square meter) positioned random-systematically across the entire marsh or stratified by elevation (low marsh, high marsh, and upland edge) along transects running perpendicular to the main tidal channel at > 10-meter intervals starting at a random distance within first interval, at impacted/restored and reference sites. | For all projects, at time of maximum standing biomass: mid-July through August (once per year) |
| Abundance | Percent cover per square meter by species | ||
| Height | Mean height of 3 tallest individuals of each species of concern per square meter | ||
| Density | Number of shoots per square meter in plots restricted to species of concern | Permanent plots established within distinct stands of species of concern | |
Nekton |
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| Composition | Identity of each animal sampled |
Methods apply to all variables: Seine and block nets (0.25-inch mesh) in larger creeks and channels at impacted/ restored and reference sites (3 tows, 10-15 meters long/site). Record length, average width, average depth of towed area. And Throw traps or lift nets in pools and throw traps, lift, or ditch nets (all 0.125-inch mesh) in small creeks or ditches at impacted/restored and reference sites (5 pool and 5 creek and/or 5 ditch samples/site). Record length, width and average depth of sample. |
For all projects, at mid-tide during a spring tide in August (once per year) |
| Species richness | Total number of species represented | ||
| Density | Number of animals per square meter | ||
| Length | Length (fish, shrimp) or width (crabs) of 15-20 individual animals (randomly selected) per species, to nearest 0.5 mm | ||
| Biomass | Wet weight of 15-20 animals per species already measured for length | ||
Birds |
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| Density | Number of birds per hectare, by species |
Methods apply to all variables: 20-minute observation periods in the morning from site-specific vantage points that provide an uninterrupted view of at least a portion of the salt marsh, at impacted/restored and reference sites |
For all projects, at high and low tides: 2 times in May/June for breeding season; once per week March-April and October-November for waterfowl migration; once per week in July-September during shorebird migration (minimum 7 times per year April-October) |
| Guild richness | Number of birds per guild: waterfowl, shorebirds, wading birds, aerial foragers, or passerines | ||
Invertebrates |
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| Mosquitoes | Number of mosquito larvae and pupae per square meter | Permanent stations in pool/wet areas, with 3 dips of 350-milliliter cup in 3-meter-radius circles, at impacted/restored and reference sites (10 dip stations/site) | For all projects, at low tide, weekly from May-September (12-15 times per year) |
Additional variables |
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| Variable name | Description |
Hydrology |
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| Tidal creek cross-section | Cross-section profiles of major tidal creeks measured at permanent locations |
| Surface-water chemical and physical characteristics | Water quality parameters sampled in main tidal channel: dissolved oxygen, salinity, temperature, and pH |
| Current profiles | Tidal current in main channel assessed over several tidal cycles |
Soils and sediments |
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| Organic matter | Organic content of 20-centimeter soil cores sectioned into 5-centimeter segments |
| Sediment accretion rate | Accumulation of inorganic and organic material above a marker horizon over a known time interval |
| Sediment elevation | Short-term changes in sediment elevation measured with Sediment Elevation Tables |
| Redox potential | Redox potential at 1 centimeter and 15 centimeter depths |
| Peat depth | Vertical measure of subsurface peat layer |
| Sulfides | Concentration of sulfide in pore water |
Vegetation |
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| Photo stations | Panoramic views of entire marsh from permanent stations from several compass bearings |
| Above-ground biomass | Biomass of living, above-ground plant material collected from additional, randomly positioned quadrat in vicinity of permanent or temporary quadrat |
| Stem density | Number of shoots per square meter, by species, within permanent or temporary quadrats |
| Proportion flowering | Proportion of shoots of each species that are flowering within permanent or temporary quadrats |
Nekton |
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| Biomass | Wet weight of individuals in sample, by species, recorded from trap/net samples |
| Fish growth | Fish condition (length/biomass) within size classes for selected species collected in trap/net samples |
| Fish diet | Gut contents of subsample of fish collected in trap/net samples |
Birds |
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| Species richness | Total number of avian species represented |
| Feeding/breeding behavior | Type of behavior (e.g., feeding, roosting, breeding, preening) per observation interval, by species |
| Habitat suitability link | Habitat types used by bird species (e.g., mud flats, pool, creek, submerged aquatic vegetation, algal mats, marsh zone) |
| Small passerines and other cryptic species | 20-minute observation periods from center of 50-meter-radius counting circles established in the salt marsh |
| Birds in the buffer | 20-minute observation periods from center of 50-meter-radius counting circles established in the habitat adjacent to the salt marsh |
| Waterfowl in winter | 20-minute observation periods from site-specific vantage points continued throughout the winter (as long as marsh is ice free) |
Invertebrates |
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| Macroinvertebrate density | Number of macroinvertebrates per sample area |
| Macroinvertebrate richness | Number of macroinvertebrate taxa per sample area |
Printer-friendly versions of the Gulf of Maine Salt Marsh Monitoring Protocol:
Word (80 KB) • PDF (104 KB)
Original protocol developed in 1999 (includes background information and rationale):
Regional Standards to Identify and Evaluate Tidal Wetland Restoration in the Gulf of Maine: A GPAC Workshop Report