Proceedings of the Third International Conference on Invasive ...

More documents

Recommendations

Info

<strong>Proceedings</strong> <strong>of</strong> <strong>the</strong> <strong>Third</strong> <strong>International</strong> <strong>Conference</strong> on Invasive SpartinaChapter 3: Ecosystem Effects <strong>of</strong> Invasive SpartinaAno<strong>the</strong>r assumption <strong>of</strong> our habitat value models wasthat exposed mudflat areas are used evenly by shorebirds,and thus in direct proportion to <strong>the</strong>ir temporal availability.However, we know that individuals <strong>of</strong> many species tendto forage along <strong>the</strong> rising or receding tide line (Colwell andLandrum 1993; Durell et al. 1997), as invertebrates are moreabundant and more accessible in wet substrates and tendto burrow deeper as <strong>the</strong> tide recedes and <strong>the</strong> mud dries out(Goss-Custard 1984; White 1995). For shorebirds that onlyforaged along <strong>the</strong> tide line, any given full tidal range mudflatshould support a constant number <strong>of</strong> birds as long as someminimum mudflat area was exposed, and shorebird densities(with respect to exposed mudflat) should increase as <strong>the</strong> tiderises. In reality, it is likely that some intermediate conditionexists and mudflat use patterns vary by species. In SanFrancisco Bay we have observed that Semipalmated Plover,Least Sandpiper, and Black-bellied Plover tend to foragehigher along <strong>the</strong> tidal gradient, whereas Dunlin, dowitchers,Marbled Godwit, and o<strong>the</strong>r species forage closer to <strong>the</strong> tideline (PRBO unpubl. data; USGS unpubl. data).Shorebird densities are also known to vary accordingto <strong>the</strong> uneven distribution <strong>of</strong> sediments, prey densities, andprey availability across <strong>the</strong> intertidal zone (Burger et al.1977; Goss-Custard et al. 1977; Puttick 1977; Page et al.1979; Quammen 1982, Colwell and Landrum 1993; Yates etal. 1993). This highlights <strong>the</strong> need to study <strong>the</strong> spatial distribution<strong>of</strong> shorebirds and <strong>the</strong>ir invertebrate prey over SanFrancisco Bay mudflats, especially given <strong>the</strong> dynamic nature<strong>of</strong> <strong>the</strong> largely non-native invertebrate community (Nichols etal. 1986; Cohen and Carlton 1998).With respect to our estimates <strong>of</strong> mudflat elevation andtidal inundation, we used a simple approach that involvedassuming an unrealistic linear mudflat slope. While highresolutiontopographic/ bathymetric data were not availablefor <strong>the</strong> entire South Bay mudflat region at <strong>the</strong> time <strong>of</strong> thisstudy, we hope that recently-obtained Light Detection andRanging (LiDAR) data (Foxgrover and Jaffe 2005) may beused to improve our models in <strong>the</strong> future.Finally, our model predictions were based on a staticpicture <strong>of</strong> mudflat spatial extent and elevation. In reality,<strong>the</strong>re are several factors in addition to hybrid Spartina spreadthat may affect mudflat extent and quality, including sea levelrise (Donnelly and Bertness 2001; Galbraith et al. 2002),tidal marsh restoration, and natural geomorphic processes(Foxgrover et al. 2004). Thus it would be useful to apply ourmodels to future mudflat predictions developed by coastalgeomorphologists.CONCLUSIONThe above-described models <strong>of</strong> Spartina inundationtolerance and shorebird habitat value allowed us to generatepreliminary predictions about <strong>the</strong> potential impact <strong>of</strong>future Spartina spread on South Bay shorebird populations.Because mudflat habitat availability and Spartina spreadpotential are both determined by tidal inundation frequency,<strong>the</strong> areas <strong>of</strong> greatest value to shorebirds coincide with <strong>the</strong>areas <strong>of</strong> greatest Spartina invasion potential. In addition,<strong>the</strong> eastern shore mudflats, which had <strong>the</strong> highest recordedshorebird densities, are adjacent to one <strong>of</strong> <strong>the</strong> sites <strong>of</strong> initialSpartina invasion at Coyote Hills Slough, increasing <strong>the</strong>irsusceptibility to Spartina encroachment.Due to various sources <strong>of</strong> uncertainty, our preliminaryanalysis resulted in a wide range <strong>of</strong> predictions: a 14% to 54%loss in mudflat area, and a 27% to 80% loss in habitat valueacross <strong>the</strong> three Spartina spread scenarios examined. At <strong>the</strong>low end, this represents a significant loss <strong>of</strong> habitat for shorebirds,which may or may not result in population declines.At <strong>the</strong> high end, our predictions suggest an extreme changein habitat availability that would almost certainly reduce <strong>the</strong>number <strong>of</strong> foraging shorebirds in <strong>the</strong> South Bay.At <strong>the</strong> same time, o<strong>the</strong>r major changes are occurring in<strong>the</strong> South Bay, including <strong>the</strong> restoration <strong>of</strong> up to 5,000 hectares<strong>of</strong> commercial salt ponds to tidal, muted, and managedmarsh. The loss <strong>of</strong> <strong>the</strong>se salt ponds, which currently serveas valuable foraging and roosting habitat, may also reduceshorebird numbers (Stralberg et al. 2006). Thus we suspectthat South Bay shorebird populations may suffer from multiplenegative impacts within a relatively short timeframe ifSpartina spread is not arrested, reducing <strong>the</strong> value <strong>of</strong> SanFrancisco Bay as a major migratory stopover and winteringsite. Additional research and modeling will be needed toassess <strong>the</strong> cumulative effects <strong>of</strong> habitat change on shorebirds,while large-scale, integrated habitat conservation planningmay help to mitigate <strong>the</strong>se negative effects.AUTHORS’ NOTE:Due to extensive Spartina control efforts since <strong>the</strong>writing <strong>of</strong> this paper, Spartina spread now poses much less<strong>of</strong> an immediate threat to shorebirds in San Francisco Bay.ACKNOWLEDGMENTSThis project was requested by <strong>the</strong> Invasive SpartinaProject (ISP), and funded by <strong>the</strong> California CoastalConservancy, <strong>the</strong> State Resources Agency, and <strong>the</strong> CALFEDProgram, under contract #02-212. We would like to thankKaty Zaremba and Peggy Ol<strong>of</strong>son <strong>of</strong> <strong>the</strong> ISP, Debra Ayres,Don Strong, Janie Civille and Ted Grosholz <strong>of</strong> UC Davis,and Bruce Jaffe and John Takekawa <strong>of</strong> USGS for <strong>the</strong>ir valuableinput and support. We are also grateful to Josh Collinsand Stuart Siegel for advice on methods, to Hildie Spautz forassistance with <strong>the</strong> literature review, and to an anonymousreviewer for feedback on an earlier draft <strong>of</strong> this manuscript.Finally, we are very grateful for <strong>the</strong> assistance <strong>of</strong> hundreds <strong>of</strong>volunteers who made <strong>the</strong> shorebird surveys possible. This isPRBO contribution number 1221.REFERENCESAnttila, C.K., C.C. Daehler, N.E. Rank, and D.R. Strong. 1998.Greater male fitness <strong>of</strong> a rare invader (Spartina alterniflora,Poaceae) threatens a common native (Spartina foliosa) withhybridization. Am. J. Bot. 85:1597–1601.Ayres, D.R., D. Garcia-Rossi, H.G. Davis, and D.R. Strong. 1999.Extent and degree <strong>of</strong> hybridization between exotic (Spartina- 181 -
Chapter 3: Ecosystem Effects <strong>of</strong> Invasive Spartina<strong>Proceedings</strong> <strong>of</strong> <strong>the</strong> <strong>Third</strong> <strong>International</strong> <strong>Conference</strong> on Invasive Spartinaalterniflora) and native (S. foliosa) cordgrass (Poaceae) inCalifornia, USA determined by random amplified polymorphicDNA (RAPDs). Mol. Ecol. 8:1179-1186.Ayres, D.R., Zaremba, K., Sloop, C.M., Strong, D.R., 2008. Sexualreproduction <strong>of</strong> cordgrass hybrids (Spartina foliosa x al-terniflora)invading tidal marshes in San Francisco Bay. Divers.Distrib. 14:187-195.Bascand, L.D. 1970. The roles <strong>of</strong> Spartina species in New Zealand.Proc. N.Z. Ecol. Soc. 17:33-40.Buchanan, J.B. 2003. Spartina invasion <strong>of</strong> Pacific coast estuariesin <strong>the</strong> United States: implications for shorebird conservation.Wader Study Group Bulletin 100:47-49.Burger, J., M.A. Howe, D.C. Hahn, and J. Chase. 1977. Effects<strong>of</strong> tide cycles on habitat selection and habitat partitioning bymigrating shorebirds. Auk 9:743-758.Callaway, J.C., and M.N. Josselyn. 1992. The introduction andspread <strong>of</strong> smooth cordgrass (Spartina alterniflora) in South SanFrancisco Bay. Estuaries 15:218-226.Civille, J.C., K. Sayce, S.D. Smith, and D.R. Strong. 2005.Reconstructing a century <strong>of</strong> Spartina alterniflora invasion withhistorical records and contemporary remote sensing. Ecoscience12:330-338.Cohen, A.N. and J.T. Carlton. 1998. Accelerating invasion rate in ahighly invaded estuary. Science 279:555-558.Collins, J.N. 2002. Invasion <strong>of</strong> San Francisco Bay by smooth cordgrass,Spartina alterniflora: a forecast <strong>of</strong> geomorphic effects on<strong>the</strong> intertidal zone. Unpublished report <strong>of</strong> San Francisco EstuaryInstitute, Oakland, CA.Colwell, M.A. and S.L. Landrum. 1993. Nonrandom shorebirddistribution and fine-scale variation in prey abundance. Condor95:94-103.Daehler, C.C. and D.R. Strong. 1996. Status, prediction and prevention<strong>of</strong> introduced cordgrass Spartina spp. invasions in Pacificestuaries, USA. Biological Conservation 78:51-58.Daehler, C.C. and D.R. Strong. 1997. Hybridization betweenintroduced Smooth Cordgrass (Spartina alterniflora) and nativeCalifornia cordgrass (S. foliosa) in San Francisco Bay, California,USA. American Journal <strong>of</strong> Botany 84:607-611.Donnelly, J.P. and M.D. Bertness. 2001. Rapid shoreward encroachment<strong>of</strong> salt marsh cordgrass in response to accelerated sea-levelrise. PNAS 98:14218-14223.Durell, S.E., A. LeDit, J.D. Goss-Custard, and R.T. Clarke. 1997.Differential response <strong>of</strong> migratory subpopulations to winterhabitat loss. J. Appl. Ecol. 34:1155-1164.ESRI. 2002. ArcInfo 8.3. Environmental Systems Research Institute,Redlands, CA.Evans, P.R. 1986. Use <strong>of</strong> <strong>the</strong> herbicide ‘Dalapon’ for control <strong>of</strong>Spartina encroaching on intertidal mudflats: beneficial effectson shorebirds. Colonial Waterbirds 9:171-175.Foxgrover, A.C., S.A. Higgins, M.K. Ingraca, B.E. Jaffe, and R.E.Smith. 2004. Deposition, erosion, and bathymetric change inSouth San Francisco Bay: 1858-1983: U.S. Geological SurveyOpen-File Report 2004-1192.Foxgrover, A.C., B.E. Jaffe. 2005. South San Francisco Bay 2004topographic lidar survey: Data overview and preliminaryquality assess-ment, U.S. Geological Survey Open-File ReportOFR-2005-1284, version 1.0. http://pubs.usgs.gov/<strong>of</strong>/2005/1284/.Galbraith, H., R. Jones, R. Park, J. Clough, S. Herrod-Julius, B.Harrington, and G. Page. 2002. Global climate change and sealevel rise: potential losses <strong>of</strong> intertidal habitat for shorebirds.Waterbirds 25:173-183.Goss-Custard, J.D. 1979. Effect <strong>of</strong> habitat loss on <strong>the</strong> numbers <strong>of</strong>overwintering shorebirds. Studies in Avian Biology 2:167-177.Goss-Custard, J. D. 1984. Intake rates and food supply in migratingand wintering shorebirds. In: Burger, J. and B.L. Olla, eds.Shorebirds: Migration and Foraging Behaviour, pp. 233-270.Plenum Press, London and New York.Goss-Custard, J.D. 2003. Fitness, demographic rates and managing<strong>the</strong> coast for wader populations. Wader Study Group Bulletin100:183-191.Goss-Custard, J.D., R.E. Jones, and P.E. Newbery. 1977. Theecology <strong>of</strong> <strong>the</strong> Wash. I. Distribution and diet <strong>of</strong> wading birds(Charadrii). J. Appl. Ecol. 14:681-700.Goss-Custard, J. D. and M. E. Moser. 1988. Rates <strong>of</strong> change in <strong>the</strong>numbers <strong>of</strong> Dunlin, Calidris alpina, wintering in British estuariesin relation to <strong>the</strong> spread <strong>of</strong> Spartina Anglica. J. Appl. Ecol.25:95-109.Jaques, D. 2002. Shorebird status and effects <strong>of</strong> Spartina alternifloraat Willapa NWR Unpublished report. US Fish and WildlifeService, Willapa Bay National Wildlife Refuge.Josselyn, M. 1983. The ecology <strong>of</strong> San Francisco Bay tidal marshes:a community pr<strong>of</strong>ile. U.S. Fish and Wildlife Service, Div. <strong>of</strong>Biological Services, FWS/OBS-83/23. Washington D.C.Josselyn, M., J. Zedler, and T. Griswold. 1990. Wetland mitigationalong <strong>the</strong> Pacific Coast <strong>of</strong> <strong>the</strong> United States. In: Kentula, J,A, andM.E. Kusler, eds. Wetland Creation and Restoration: <strong>the</strong> Status<strong>of</strong> <strong>the</strong> Science. Island Press, Washington D.C.Nichols, F.H., J.E. Cloern, S.N. Luoma, and D.H. Peterson. 1986.The modification <strong>of</strong> an estuary. Science 231:567-573.Page, G.W., L.E. Stenzel, and J.E. Kjelmyr. 1999. Overview <strong>of</strong>shorebird abundance and distribution in wetlands <strong>of</strong> <strong>the</strong> PacificCoast <strong>of</strong> <strong>the</strong> contiguous United States. Condor 101:461-471.Page, G.W., L.E. Stenzel, and C.M. Wolfe. 1979. Aspects <strong>of</strong> <strong>the</strong>occurrence <strong>of</strong> shorebirds on a central California estuary. Studiesin Avian Biology 2:15-32.Puttick, G.M. 1977. Spatial and temporal variations in intertidalanimal distribution at Langebaan Lagoon, South Africa. RoyalSociety <strong>of</strong> South Africa. Trans. 42:403-440.Quammen, M.L. 1982. Influence <strong>of</strong> subtle substrate differenceson feeding by shorebirds on intertidal mudflats. Mar. Biol.71:339-343.Ranwell, D.S. 1964. Spartina salt marshes in sou<strong>the</strong>rn England:II. rate and seasonal pattern <strong>of</strong> sediment accretion. J. Ecol.52:79-94.Sayce, K. 1988. Introduced cordgrass, Spartina alterniflora Loiselin saltmarshes and tidelands <strong>of</strong> Willapa Bay, Washington. Reportto US Fish and Wildlife Service, Willapa NWR.SFEI. 1998. EcoAtlas beta release, version 1.5b4. San FranciscoEstuary Institute, Oakland, CA.Stata. 2003. Intercooled Stata 8.0 for Windows. Stata Corporation,College Station, TX.Stenzel, L.E., C.M. Hickey, J.E. Kjelmyr, and G.W. Page. 2002.Abundance and distribution <strong>of</strong> shorebirds in <strong>the</strong> San FranciscoBay area. Western Birds 33:69-98.Stralberg, D., M. Herzog, N. Warnock, N. Nur, and S. Valdez. 2006.Habitat-based modeling <strong>of</strong> wetland bird communities: an evaluation<strong>of</strong> potential restoration alternatives for South San FranciscoBay. PRBO unpubl. report to California Coastal Conservancy.http://www.prbo.org/wetlands/hcm.Takekawa, J.Y., N. Warnock, G.M. Martinelli, A.K. Miles, andD. C. Tsao. 2002. Waterbird use <strong>of</strong> bayland wetlands in <strong>the</strong> San- 182 -
Page 2 and 3:
Proceedings <stron
Page 4 and 5:
FORWARD & ACKNOWLEDGEMENTSThe <stro
Page 6 and 7:
TABLE OF CONTENTSForward & Acknowle
Page 9 and 10:
Community Spartina Education and St
Page 11 and 12:
included the docum
Page 14:
CHAPTER ONESpartina Biology
Page 17 and 18:
Chapter 1: Spartina Biology
Page 19 and 20:
Page 21 and 22:
Page 23 and 24:
Page 25 and 26:
Page 28 and 29:
Proceedings <stron
Page 30 and 31:
Proceedings <stron
Page 32 and 33:
Proceedings <stron
Page 34:
Proceedings <stron
Page 37 and 38:
Page 39 and 40:
Page 42 and 43:
Proceedings <stron
Page 44:
Proceedings <stron
Page 47 and 48:
Page 49 and 50:
Page 51 and 52:
Page 53 and 54:
Page 55 and 56:
Page 57 and 58:
Page 60 and 61:
Proceedings <stron
Page 62 and 63:
Proceedings <stron
Page 64 and 65:
Proceedings <stron
Page 66:
Proceedings <stron
Page 69 and 70:
Page 71 and 72:
Page 74 and 75:
Proceedings <stron
Page 76:
Proceedings <stron
Page 79 and 80:
Chapter 2: Spartina Distribution an
Page 81 and 82:
Page 83 and 84:
Page 86 and 87:
Proceedings <stron
Page 88 and 89:
Proceedings <stron
Page 90 and 91:
Proceedings <stron
Page 92 and 93:
Proceedings <stron
Page 94 and 95:
Proceedings <stron
Page 96 and 97:
Proceedings <stron
Page 98:
Proceedings <stron
Page 101 and 102:
Page 103 and 104:
Page 105 and 106:
Page 108 and 109:
Proceedings <stron
Page 110:
Proceedings <stron
Page 113 and 114:
Page 115 and 116:
Page 117 and 118:
Page 119 and 120:
Page 122 and 123:
Proceedings <stron
Page 124 and 125:
Proceedings <stron
Page 126 and 127:
Proceedings <stron
Page 128:
Proceedings <stron
Page 131 and 132:
Page 134 and 135:
Proceedings <stron
Page 136 and 137:
Proceedings <stron
Page 138 and 139:
Proceedings <stron
Page 140:
CHAPTER THREEEcosystem Effects <str
Page 143 and 144: Chapter 3: Ecosystem Effects <stron
Page 148 and 149: Proceedings <stron
Page 152: Proceedings <stron
Page 244 and 245:
Proceedings <stron
Page 246:
Proceedings <stron
Page 249 and 250:
Chapter 4: Spartina Control and Man
Page 251 and 252:
Page 253 and 254:
Page 255 and 256:
Page 257 and 258:
Page 259 and 260:
Page 261 and 262:
Page 263 and 264:
Page 265 and 266:
Page 267 and 268:
Page 269 and 270:
Page 271 and 272:
Page 273 and 274:
Page 276 and 277:
Proceedings <stron
Page 278 and 279:
Proceedings <stron
Page 280 and 281:
Proceedings <stron
Page 282 and 283:
Proceedings <stron
Page 284 and 285:
Proceedings <stron
Page 286 and 287:
Proceedings <stron
Page 288 and 289:
Proceedings <stron
Page 290:
Proceedings <stron
show all

Proceedings of the Third International Conference on Invasive ...

Create successful ePaper yourself

Delete template?

Save as template?