Interactions between tidal marsh restoration and existing estuarine habitats: Local and large-scale effects

The restoration efforts of the South Bay Salt Pond Restoration Project (SBSPRP) involve a region with surface area comparable to the existing estuarine habitat to which these restored habitats will be connected.  This leads to a fundamental question for the restoration process: “What are the implications of restoration at this scale for the existing estuarine ecosystem?”    The effects of tidal marsh restoration around the perimeter of South San Francisco Bay will be manifested, to some extent, in changes to the tidal dynamics, the salinity distribution and the erosion, transport and deposition of sediment in the South Bay.  The magnitude and extent of these effects, however, are uncertain, and are the emphasis of our research on the system.  In 2006, two detailed field campaigns were carried out adjacent to one of the first restoration sites, the “Island Ponds”.   The first, in spring 2006, coincided with the breaching of the ponds and was characterized by large freshwater flows from the adjoining watershed.  Our instrument deployment focused on the axis of the adjoining estuary (Lower Coyote Creek) and we have analyzed the response of the system to both restoration and freshwater flows.  The second deployment, in fall 2006, was focused on the exchange between Lower Coyote Creek and the Island Ponds, with instrumentation adjacent to and within one of the breaches.  The emphasis of our analysis of this data is on the tidally-forced exchange between the restoration sites and the estuary. Based on these observations of tidal stage, currents, salinity, temperature and suspended sediments, we will discuss the nature of the connection between the restoration sites and the adjoining estuary, with an emphasis on the local dynamics.  We will conclude with a discussion of what modeling and analysis tools are required to extent our understanding to the larger-scale system.