From Waypoints to Watersheds: Cross-Scale Explorations of Stressor-State Correlations for the Inter-Tidal Zone of California

Joshua N. Collins, Martha Sutula, Eric Stein, Cristina Grosso, Eric Wittner

San Francisco Estuary Institute, 7770 Pardee Lane, Oakland, CA 94621,
josh@sfei.org, 510 746 7365

The EMAP Intensification Project for San Francisco Bay and the Southern California Bight was designed to (1) assess sediment chemistry, benthos, and vegetation per m2 plot of the inter-tidal zone; (2) assess vegetation per inter-tidal drainage system and encompassing habitat patch; and (3) explore cross-scale correlations between landscape-level stressors and the conditions within habitat patches, drainage systems, and plots. The project also enabled us to examine patterns of inter-tidal habitat fragmentation using regional rule sets to define alternative patch types, barriers between patches, and inter-patch distance. Initial results indicate that, as watersheds fill with people, the number of inter-tidal stressors increases, the amount of inter-tidal edge also increases, and the integrity of the plant community decreases, regardless of salinity regime. Cross-scale correlations between stressors and sediment chemistry or benthos remain to be tested. Since Euro-American contact, the inter-tidal ecosystem has become more fragmented for most, but not all, endemic wildlife of highest concern to mangers. The fragmentation is due to a decreased number of patches, and their increased isolation, rather than a change in the relative abundance of large patches. Small patches of habitat have always been an important component of these inter-tidal ecosystems. These findings have significant meaning in the context of coastal zone planning and restoration.

Keywords: Wetlands, Fragmentation, Multi-scale assessment