The Saltmarsh Project: Getting Fresh is a Good Thing

Early in 2002, Jeff Marliave, aided by the Aquarium's River Works program volunteers, created a saltmarsh at the Coal Harbour mouth of the BC Hydro Salmon Stream Project in Stanley Park. The saltmarsh project, originally proposed in order to give the Stream Project's salmon smolts a place to acclimatize to saltwater and feed before beginning their ocean journeys, was also designed to function as an experiment that would assess how much fresh water was needed for saltmarsh plants to thrive.

Because the seawall blocks any groundwater flows that would lower the salinity at the planting sites, plots consisting of soil beds of dredged silt were installed. The beds west of the stream included piping allowing for variable amounts of fresh water while beds east of the stream (the study's control sites) were left to be influenced only by the ocean. Next, in early spring, the saltmarsh was planted with 3 species specially-adapted for saltmarsh ecosystem: salt grass, gumweed and sedge. It wasn't long before some early results of this experiment were ver apparent.

At the control sites, where the plants were left to survive with simply salt water, only the salt grass survived. In contrast, at sites receiving fresh water, all three species thrived. These photomurals depict the differences in plant survival. These research plots highlight the benefits of having natural ground water flows at saltmarsh ecosystems.

This is the saltmarsh with only salt water: (click to enlarge)

This is the saltmarsh with added fresh water: (click to enlarge)