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The Double Irony of Hybrid Spartina in San Francisco Bay
Debra Ayres, Curt Daehler, Christina Sloop, Carina Antilla, Dino Rossi, Katie Zaremba, et
al. and Don Strong.
San Francisco Estuary.!
Spartina alterniflora introduced by Army Corps of Engineers, ca 1970.
Native California cord grass, Spartina foliosa hybridized with S. alterniflora and spread to ca. 325 ha by 2004 S. alterniflora
S. foliosa
Hybrid
S. alterniflora
x
S. foliosa
Debra Ayres, Christina Sloop, Curt Daehler et al. (and D. R. Strong) many publications from 1994.
More than 1 million shorebirds
38 species, 2 endangered, use SFB in annual migration.
SFB is a site of hemispheric importance,
highest possible conservation ranking
Hybrid Spartina in SFB is a substantial threat to the foraging areas on
open mud of migratory shorebirds.
Over 1 million shorebirds use San Francisco Bay each year. As a result, San Francisco Bay is recognized as a Western Hemisphere Shorebird Reserve Network Site of Hemispheric Importance for shorebirds – the highest possible ranking
The Invasive Spartina Project begun 2003 to control the hybrid swarm
Reduced the extent from ca. 325 ha to 13 ha by 2010.
This was a success.
Primary conservation objective preserving open mud for shorebirds.
By 2008 expert opinion focused on the fact that hybrid Spartina is a boon to the non-migratory,
endangered Ridgeway’s rail,
so reduced by hunting and habitat destruction to have received endangered species status.
Control of hybrid Spartina correlated with rapid decrease in numbers of rails.
The double irony is that tall dense Spartina acts to impede the highest
tides and erosion on shorelines (well studied in Europe).
San Francisco Bay will see substantial rise in sea level and high water.
Hybrid Spartina could be of great value in protection of the shore.