ntertidal Ecological Health and StressorsAmbient Survey of

Project DescriptionAs part of the USEPA Western Pilot of Environmental Monitoring Assessment Program (WEMAP), the Southern California Coastal Water Research Project (SCCWRP) and the San Francisco Estuary Institute (SFEI) are: testing a stratified-random sampling design to assess ambient intertidal conditions, exploring correlations between intertidal conditions and indicators of anthropogenic

stress across spatial scales, anddeveloping new tools for profiling habitats and stressors.

This poster displays the study approach, initial landscape profiles, and preliminary assessments of bayland plant community structure for San Francisco Bay. Future analyses will focus on chemical profiles and benthic community structure.

Initial analyses focus on correlations between conditions at different spatial scales. These results help generate testable hypotheses about the effects of land use and human demographics at the watershed scale on the conditions of buffers, patches, drainage areas, and local intertidal plots.

A single plot measure of salinity helps explain plant species

richness of the encompassing marsh drainage system. As

salinity decreases, plant species richness increases.

Drainageand Plot

PatchSimilar numbers of plant

species are likely to inhabit small and large patches of

tidal marshland.

Tidal marsh patches with abundant edge per unit area tend to support fewer native plant species, regardless of

salinity regime.

The quality of tidal marsh buffers decreases with

adjacent increases in human population density.

Buffer

Exploring Data Across Spatial Scales

Joshua Collins1, Eric Wittner1, Cristina Grosso1, Diana Stralberg2, and Martha Sutula31San Francisco Estuary Institute, 7770 Pardee Lane, Oakland, CA 94621 2Point Reyes Bird Observatory, 4990 Shoreline Highway, Stinson Beach, CA 94970 3Southern California Coastal Water Research Project, 7171 Fenwick Lane, Westminster, CA 92683

USEPA provided funding for this project. We are very thankful to Tom Parker, Mike Vasey, Diana Benner, David Wright, Leslie Lazarotti, and Amy Langston of San Francisco State University, John Callaway of the University of San Francisco, and Rusty Fairey of the Moss Landing Marine Laboratory for field work and data entry. We thank Maggi Kelly of the University of California at Berkeley, Nadav Nur of PRBO, and Howard Shellhammer of San Jose State University for help with habitat patch definitions.

Acknowledgements

Random Sampling DesignThirty (30) 1-m2 sample plots were randomly selected from all possible plots in the intertidal zone of San Francisco Bay. The sampling design recognizes that each randomly selected plot exists within a local intertidal drainage system, which in turn exists within a patch of intertidal habitat, and that each patch can be assigned to a larger terrestrial watershed. This design yields paired values for stressors and response variables for all spatial scales of habitat restoration and land management.

Patch Type 4 includes diked as well as tidal baylands, and the modern condition therefore reflects the historical distribution and abundance of tidal marsh.

These two graphs show that Patch Types 1 and 4 tended to be larger before Euro-American contact. But even then, most patches were less than 10 ha in size, due to natural topographic controls. Small habitat patches were a natural feature of the intertidal zone for all wildlife.

Bayland Landscape ProfileHabitat fragmentation varies among wildlife species, depending on their habitat affinities and barriers to movement. Using rails, small mammals, passerine birds, shorebirds and waterfowl as examples, four types of habitat patches were delineated.

Type 1 patches are tidal marsh bounded by tidal flat, any non-tidal area or open water at least 200 feet wide, any man-made levees, and any roads four-lane or larger.

Type 2 includes Type 1 plus areas of tidal marsh or muted tidal marsh that are separated from Type 1 patches by man-made levees.

Type 3 includes Type 2 plus any areas of abandoned salt ponds, ruderal baylands, and diked managed marsh that are separated from Type 2 patches by man-made levees.

Type 4 includes Type 3 plus upland fill less than 60 m wide, low- and medium-salinity salt ponds, treatment ponds, and mudflats separated from Type 3 patches by levees, roads, or channels of any width.

Types 1 and 4 Bayland Habitat Patches Past and Present in North Bay

23 patches

Modern Type 1 Patches

26 patches

Modern Type 4 PatchesHistorical Type 1 Patches

76 patches

Findings: Simple marsh shapes are better

Cumulative Type 1 Patch Areas Past and Present

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Example of data hierarchy for a plot in Petaluma Marsh.

Plot

Cumulative Type 4 Patch Areas Past and Present

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Plant Species Richness of Drainage SystemRelated to Plot Porewater Salinity

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The median size class of Type 1 patches has significantly decreased since Euro-American contact, reflecting the unnatural loss and fragmentation of tidal marshland.

Type 1 Patch Buffer Quality Related to Human Population Densityin Adjacent Watershed

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WatershedThe amount of edge per unit area of tidal marsh decreases with development of the

adjacent watersheds.

1.The random design for regional ambient sampling was cost-effective.

2.Measures of intertidal habitat fragmentation are scale-and species-dependent.

3.Small patches are natural components of the intertidal landscape, but modern land use has increased the abundance of smallpatches.

4.Restoration of small patches can benefit the conservation of tidal marsh plant communities.

5.Tidal marsh plant species richness increases as porewater salinity decreases. Brackish marshes are relatively species-rich.

6.Patches of tidal marsh adjacent to development tend to have abundant edge per unit area.

7.For tidal marsh patches of any size and salinity, patches with less edge per unit area support more species of native plants.

8.The quality of marsh buffer zones declines as the number of people increases in adjacent watersheds.

9.Working hypothesis: adjacent development has led to unnaturally complex tidal marsh shapes with an overabundance of upland margin that becomes degraded as human population density increases, resulting in local decreases in native plant species diversity.

55 patches

Historical Type 4 Patches