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<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 SpartinaA.sulfide (μM)35302520151050B.600ammonium (μM)5004003002001000CTRL HET ILY MACCTRL HET ILY MACFig. 1: Results from Experiment 1 by treatment (CTRL=defaunated control,HET=Heteromastus filiformis, ILY=Ilyanassa obsoleta, andMAC=Macoma petalum). A. Porewater sulfide concentration. B. Porewaterammonium concentration. N=6 for all treatments.treatments, although <strong>the</strong>se differences were not significant(Fig. 2B and 2C).DISCUSSIONOur preliminary results suggest that under laboratoryconditions benthic macroinvertebrates can affect bothporewater ammonium concentrations and Spartinaalterniflora seedling growth. We found that both H.filiformis and M. petalum lowered porewater ammoniumconcentrations relative to controls, while surface grazers hadno obvious effect on porewater ammonium or sulfides.Benthic invertebrates can decrease porewater ammoniumand soluble sulfide concentrations by flushing porewatersolutes from sediments during burrow construction andirrigation (Aller 1982; Christensen et al. 2000) and bystimulating oxidation-reduction reactions (Pelegri andBlackburn 1995; Rysgaard et al. 2000), but <strong>the</strong> magnitude <strong>of</strong>change is limited by <strong>the</strong> depth <strong>of</strong> <strong>the</strong> burrow (e.g., Aller1982; Francois et al. 2002; Michaud et al. 2006).Despite <strong>the</strong> negative effect on porewater ammoniumconcentrations, H. filiformis appeared to have a positiveeffect on soluble sulfide concentrations although this wasnot confirmed statistically. Past work has demonstrated thatinvertebrates can increase sulfate reduction rates in marinesediments (Hansen et al. 1996). A variety <strong>of</strong> mechanismsincluding removal <strong>of</strong> inhibitory metabolites, redistribution <strong>of</strong>particles, secretion <strong>of</strong> labile mucus along burrow walls, andtranslocation <strong>of</strong> labile organic matter from <strong>the</strong> surface to <strong>the</strong>deeper sediment during feeding could be responsible forincreased anaerobic metabolism and sulfide productionA.B.C.change in leaf length (cm)biomass (g)biomass (g)121086420-2-4-60.100.080.060.040.020.000.120.100.080.060.040.020.00CTRL HET ILY MACCTRL HET ILY MACCTRL HET ILY MACFig. 2: Results from Experiment 2 by treatment (CTRL=defaunated control,HET=Heteromastus filiformis, ILY=Ilyanassa obsoleta, MAC=Macomapetalum). A. Change in leaf length <strong>of</strong> Spartina alterniflora seedlings. B.Aboveground biomass <strong>of</strong> S. alterniflora seedlings. C. Belowground biomass<strong>of</strong> S. alterniflora seedlings. * indicates treatment means that differsignificantly from each o<strong>the</strong>r (post-hoc Tukey, p< 0.05). N = 9 for eachtreatment.(Wheatcr<strong>of</strong>t et al. 1994; Marinelli and Boudreau 1996; Allerand Aller 1998). However, it is not clear which mechanismswould account for <strong>the</strong> positive effect <strong>of</strong> H. filiformis onsoluble sulfides or why H. filiformis would have oppositeeffects on ammonium and sulfide.Significant differences between treatments for change intotal leaf length suggest that <strong>the</strong> benthic community has <strong>the</strong>- 167 -
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 Spartinapotential to substantially influence <strong>the</strong> establishment <strong>of</strong> S.alterniflora seedlings at <strong>the</strong> edge <strong>of</strong> <strong>the</strong> expanding marsh.Work from eastern U.S. marshes in <strong>the</strong> native range <strong>of</strong> S.alterniflora has shown growth and establishment can belimited by high porewater sulfide concentrations (Morris andDacey 1984; Bradley and Morris 1990) and by availability<strong>of</strong> ammonium in porewater (Tyler et al. 2003). At <strong>the</strong> sametime, very high ammonium can have a toxic effect on plantsalthough tolerances vary widely between species (Britto andKronzucker 2001). Ammonium toxicity for o<strong>the</strong>r marshspecies has been demonstrated at concentrations above 200μM (Tylova et al. 2008), although to our knowledge this hasnot been demonstrated for S. alterniflora. H. filiformisstimulated an increase in porewater sulfide concentrations, adecrease in porewater ammonium and a loss <strong>of</strong> S.alterniflora leaves (measured as <strong>the</strong> decrease in leaf length).In contrast, <strong>the</strong> low porewater sulfide and ammonium in <strong>the</strong>presence <strong>of</strong> M. petalum appeared to promote seedlingsuccess. In our experiments, concentrations <strong>of</strong> ammoniumexceeded 300 μM and it is possible that it had an inhibitoryeffect on seedling growth. While future work is needed toclarify <strong>the</strong> mechanisms linking benthic invertebratecommunities to seedling success, our results suggest thatboth low porewater sulfide and moderate levels <strong>of</strong> porewaterammonium are requisite for S. alterniflora seedling success.The spread <strong>of</strong> S. alterniflora and its hybrids in WestCoast estuaries may depend in part on complex interactionsbetween infaunal community structure and localbiogeochemical cycling that in turn dictate seedling success.As <strong>the</strong> invasion proceeds, changes in benthic communitystructure may ei<strong>the</strong>r facilitate or inhibit <strong>the</strong> success <strong>of</strong> S.alterniflora and its hybrids. Long-term goals for control,eradication, and restoration depend on an understanding <strong>of</strong><strong>the</strong> processes that control <strong>the</strong> establishment and expansion <strong>of</strong><strong>the</strong>se invaders.ACKNOWLEDGMENTSMany thanks to: Jay Stachowicz for generous use <strong>of</strong> hiswet lab, John Lambrinos for provision <strong>of</strong> seedlings, andRachael Blake, Nicole Christiansen, Nicole Smith, andCrystal Love for all <strong>the</strong>ir hard work. Funding was providedby NSF Biocomplexity Project (DEB-0083583).REFERENCESAller, R.C. 1982. The effects <strong>of</strong> macrobenthos on chemical properties<strong>of</strong> marine sediment and overlying water. In: P.L. McCall andM.J.S. Tevesz, eds. Animal-Sediment Relations. Plenum Press,New York, USA.Aller, R.C., and J.Y. Aller. 1998. The effect <strong>of</strong> bioirrigation intensityand solute exchange on diagenetic reaction rates in marinesediments. Journal <strong>of</strong> Marine Research 56:905–936.Berg P., and K.J. McGla<strong>the</strong>ry. 2001. A high-resolution pore watersampler for sandy sediments. Limnology and Oceanography46:203-10.Bradley, P.M., and J.T. Morris. 1990. Influence <strong>of</strong> oxygen andsulfide concentration on nitrogen uptake kinetics in Spartina alterniflora.Ecology 71:282-287.Britto, D.T., and H.J. Kronzucker. 2002. Journal <strong>of</strong> Plant Physiology159:567-584.Christensen, B., A. Vedel, and E. Kristensen. 2000. Carbon andnitrogen fluxes in sediment inhabited by suspension-feeding (Nereisdiversicolor) and non-suspension-feeding (N. virens) polychaetes.Marine Ecological Progress Series 192:203-217.Cline, J.D. 1969. Spectrophotometric determination <strong>of</strong> hydrogensulfide in natural waters. Limnology and Oceanography 14:454-8.Dai, T., and R.G. Wiegert. 1997. A field study <strong>of</strong> photosyn<strong>the</strong>ticcapacity and its response to nitrogen fertilization in Spartina alterniflora.Estuarine, Coastal, and Shelf Science 45:273-83.DeLaune, R.D., C.J. Smith, and W.H. Patrick, Jr. 1983. Relationship<strong>of</strong> marsh elevation, redox potential, and sulfide to Spartinaalterniflora productivity. Soil Science Society <strong>of</strong> America Journal47:930-5.Drake, J.A., H.A. Mooney, F. DiCastri, R.H. Groves, F.J. Kruger,M. Rejmanek, and M. Williamson, eds. 1989. Biological Invasions:A Global Perspective. John Wiley & Sons, Chichester,UK.Francois, F., M. Gerino, G. Stora, J. Durbec, and J. Poggiale. 2002.Functional approach to sediment reworking by gallery-formingmacrobenthic organisms: modeling and application with <strong>the</strong>polychaete Nereis diversicolor. Marine Ecological Progress Series229:127-136.Gallagher, J.L. 1975. Effect <strong>of</strong> an ammonium pulse on <strong>the</strong> growthand elemental composition <strong>of</strong> natural stands <strong>of</strong> Spartina alternifloraandJuncus roemerianus. American Journal <strong>of</strong> Botany62:644-648.Hansen, K., G. King, and E. Kristensen. 1996. Impact <strong>of</strong> <strong>the</strong> s<strong>of</strong>tshellclam Mya arenaria on sulfate reduction in an intertidalsediment. Aquatic Microbial Ecology 10:181 -194.King, G.M., M.J. Klug, R.G. Wiegert, and A.G. Chalmers. 1982.Relation <strong>of</strong> soil water movement and sulfide concentration toSpartina alterniflora production in a Georgia salt marsh. Science218:61-63.Levin, L.A., C. Neira, and E.D. Grosholz. 2006. Invasive cordgrassmodifies wetland trophic function. Ecology. 87:419-432.Marinelli, R.L., and B.P. Boudreau. 1996. An experimental andmodeling study <strong>of</strong> pH and related solutes in irrigated anoxiccoastal sediment. Journal <strong>of</strong> Marine Research 54:939-966.Michaud, E., G. Desrosiers, F. Mermillod-Blondin, B. Sundby, andG. Stora. 2006. The functional group approach to bioturbation:<strong>the</strong> effects <strong>of</strong> <strong>the</strong> Macoma balthica community on fluxes <strong>of</strong> nutrientsand dissolved organic carbon across <strong>the</strong> sediment-waterinterface. Journal <strong>of</strong> Experimental Marine Biology and Ecology.337:178-189.Morris, J.T., and J.W.H. Dacey. 1984. Effects <strong>of</strong> O 2 on ammoniumuptake and root respiration by Spartina alterniflora. AmericanJournal <strong>of</strong> Botany. 71:979-985.Neira, C., L.A. Levin, and E.D. Grosholz. 2005. Benthic macr<strong>of</strong>aunalcommunities <strong>of</strong> three sites in San Francisco Bay invaded byhybrid Spartina with comparison to uninvaded habitats. MarineEcological Progress Series 292:111-126.Neira, C., E.D. Grosholz, L.A. Levin, and R. Blake. 2006. Mechanismsgenerating modificaiton <strong>of</strong> benthos following tidal flat invasionby a Spartina hybrid. Ecological Applications 16:1391-1404.- 168 -
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FORWARD & ACKNOWLEDGEMENTSThe <stro
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Community Spartina Education and St
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CHAPTER ONESpartina Biology
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Chapter 1: Spartina Biology
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