Proceedings of the Third International Conference on Invasive ...

<strong>Proceedings</strong> <strong>of</strong> <strong>the</strong> <strong>Third</strong> <strong>International</strong> <strong>Conference</strong> on Invasive SpartinaChapter 1: Spartina Biologywould provide additional leverage to help protect <strong>the</strong> areas<strong>of</strong> San Francisco Bay salt marshes that are so far notimpacted by <strong>the</strong> Spartina hybrid.In <strong>the</strong> long term, it certainly is possible that this hybridevolutionary unit will spread beyond San Francisco Bay. Infact, in 2001, a hybrid individual was found in BolinasLagoon (35 kilometers away), and in 2002, five hybridswere found in Drake’s Estero, some 45 kilometers from <strong>the</strong>nearest San Francisco Bay population <strong>of</strong> hybrid entities(Zaremba and McGowan 2004). Hybrids within <strong>the</strong> bay haveincreased some 317%, particularly in <strong>the</strong> Central Bay(Zaremba and McGowan 2004). Given that <strong>the</strong> Bay is amagnet for migratory shorebirds and waterfowl, and thatmany species are flying south during fall migration, it is hardto imagine that <strong>the</strong> hybrid won’t eventually colonize <strong>the</strong>sou<strong>the</strong>rn center <strong>of</strong> distribution for S. foliosa. On <strong>the</strong> o<strong>the</strong>rhand, even given dispersal to sou<strong>the</strong>rn California, it ispossible that <strong>the</strong> hybrid will not fare as well as S. foliosa in<strong>the</strong> hotter and drier sou<strong>the</strong>rn habitats. None<strong>the</strong>less, it isadvisable for sou<strong>the</strong>rn California and Baja Californiawetland managers to remain vigilant to this possibility and toact quickly to eliminate hybrids, as was <strong>the</strong> case in BolinasLagoon and Drake’s Estero.As known by wetland ecologists for decades, S. foliosais a vital force in shaping salt marsh communities in SanFrancisco Bay, sou<strong>the</strong>rn California, and Baja California. Theintroduction <strong>of</strong> S. alterniflora into San Francisco Bay hasmost likely begun a new chapter in <strong>the</strong> evolutionary fate <strong>of</strong>S. foliosa, and in so doing, is reorganizing its relationship toa host <strong>of</strong> o<strong>the</strong>r tidal wetland species in this region. We needto forge a realistic strategy to deal with this unexpecteddevelopment. Massive eradication efforts could have <strong>the</strong>irown unexpected consequences, especially if directedtowards <strong>the</strong> hybrid. From <strong>the</strong> perspective <strong>of</strong> S. foliosa, <strong>the</strong>fact that its genome is being transformed into a new hybridentity is not, in my view, extinction per se, although thisperspective can certainly be argued and it is not aninsignificant concern. The more compelling issue, however,is how <strong>the</strong> hybrid will affect future salt marsh and mud flathabitats. Given that large-scale wetland restoration projectsare planned for <strong>the</strong> South Bay and elsewhere, it might beworth taking a pluralistic approach to managing this crisis.Design restoration activities to test different approaches,from aggressive prevention to passive observation. Give<strong>the</strong>se trials enough time to evaluate <strong>the</strong> ecological impacts <strong>of</strong>wetland restoration projects that are influenced by hybrids.To <strong>the</strong> degree possible, as in <strong>the</strong> eradication effort at Bolinasand Drake’s Estero, aggressively contain hybrid colonistswherever <strong>the</strong>y can be caught in time. Like it or not, humansare part <strong>of</strong> nature, and nature is full <strong>of</strong> surprises. In <strong>the</strong> longterm, perhaps <strong>the</strong> best we can do is manage this complexitywith respect, active curiosity (including variousexperimental approaches), and perhaps, if not fatalism, atleast a degree <strong>of</strong> tolerance and humble appreciation for <strong>the</strong>evolutionary creativity inherent in this remarkable situation.ACKNOWLEDGMENTSI thank Peggy Ol<strong>of</strong>son for inviting me to contribute thispaper to <strong>the</strong> <strong>Third</strong> <strong>International</strong> <strong>Conference</strong> on InvasiveSpartina. Constructive comments on this manuscript havebeen contributed by Drew Talley and Tom Parker. MarkBertness provided helpful feedback on <strong>the</strong> topic <strong>of</strong>foundation species.REFERENCESAntilla, C.K., C.C. Daehler, N.E. Rank, D.R. Strong. 1998. 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