IntroductionIn <strong>sediment</strong>s of high O 2 dem<strong>and</strong> <strong>isoetid</strong>sroots are restricted to the uppermost <strong>sediment</strong>layer where O 2 supply to root tips is possible(S<strong>and</strong>-Jensen et al. 2005; Raun et al. 2010).Short roots offer low anchorage <strong>and</strong> is furtherweakened <strong>in</strong> organic <strong>sediment</strong>s by low density<strong>in</strong>creas<strong>in</strong>g the risk of uproot<strong>in</strong>g <strong>and</strong> loss ofpopulations (Pulido et al. 2010). Furthermore,anoxia <strong>in</strong> roots of <strong>isoetid</strong>s leads to reducedtranslocation of nutrients with decreasedphotosynthesis <strong>and</strong> low tissue content ofnutrients as a result (Sorrell 2004; Møller &S<strong>and</strong>-Jensen 2011). To promote the return of<strong>isoetid</strong>s to their former growth sites improvedunderst<strong>and</strong><strong>in</strong>g of how <strong>isoetid</strong>s respond <strong>and</strong> copewith changes <strong>in</strong> <strong>sediment</strong> biogeochemistry isneeded. This was the ma<strong>in</strong> aim of this thesis.ReferencesArmstrong W. 1979. Aeration <strong>in</strong> higher <strong>plant</strong>s. Advances<strong>in</strong> Botanical Research 7: 225–332.Arts GHP. 2002. Deterioration of Atlantic soft watermacrophyte communities by acidification, eutrophication<strong>and</strong> alkal<strong>in</strong>isation. Aquatic Botany 73: 373-393.Beck-Nielsen D, Madsen TV. 2001. Occurrence ofViscicular-arbuscular mycorrhiza <strong>in</strong> <strong>plant</strong>s from lakes <strong>and</strong>streams. Aquatic Botany 71: 141-148Christensen PB, Sørensen J. 1986. Temporal variationof denitrification activity <strong>in</strong> <strong>plant</strong>-covered, littoral<strong>sediment</strong> from Lake Hampen, Denmark. Applied <strong>and</strong>Environmental Microbiology 51: 1174-1179Christensen KK, Andersen FØ. 1996. Influence ofLittorella uniflora on phosphorus retention <strong>in</strong> <strong>sediment</strong>supplied with artificial porewater. Aquatic Botany 55:183-197Colmer TD. 2003. Long-distance transport of gases <strong>in</strong><strong>plant</strong>s: a perspective on <strong>in</strong>ternal aeration <strong>and</strong> radialoxygen loss from roots. Plant Cell Environment 26: 17-36.Farmer AM. 1985. The occurrence of vesiculararbuscularmycorrhiza <strong>in</strong> <strong>isoetid</strong>-type submerged aquaticmacrophytes under naturally vary<strong>in</strong>g conditions. AquaticBotany 21: 245-249.Geurts JJM, Smolders AJP, Verhoeven JTA, RoelofsJGM, Lamers LPM. 2008. Sediment Fe:PO 4 ratio as adiagnostic <strong>and</strong> prognostic tool for the restoration ofmacrophyte biodiversity <strong>in</strong> fen waters. FreshwaterBiology 53: 2101–2116.Jeppesen E, Søndergaard M, Jensen JP, Havens KE,Anneville O, Carvalho L & others. 2005. Lake responseto reduced nutrient load<strong>in</strong>g – an analysis of contemporarylong-term data from 35 case sturies. Freshwater Biology50:1747-1771Keeley JE. 1998. CAM photosynthesis <strong>in</strong> submergedaquatic <strong>plant</strong>s. The botanical Review 64:121-175.Madsen TV. 1985. A community of submerged aquaticCAM <strong>plant</strong>s <strong>in</strong> Lake Kalgaard, Denmark. Aquatic Botany23: 97-108Murphy KJ. 2002. Plant communities <strong>and</strong> <strong>plant</strong> diversity<strong>in</strong> softwater lakes of northern Europe. Aquatic Botany 73:287-324Møller CL, S<strong>and</strong>-Jensen K. 2008. Iron plaques improvethe oxygen supply to root meristems of the freshwater<strong>plant</strong>, Lobelia dortmanna. New Phytologist 179: 848-56.Møller CL, S<strong>and</strong>-Jensen K. 2011. High sensitivity ofLobelia dortmanna to <strong>sediment</strong> O2 depletion follow<strong>in</strong>gorganic enrichment. New Phytologist 190: 320-331.Nielsen KB, Kjøller R, Olsson PA, Schweiger PF,Andersen FØ, Rosendahl S. 2004. Colonization <strong>and</strong>molecular diversity of arbuscular mycorrhizal fungi <strong>in</strong> theaquatic <strong>plant</strong>s Littorella uniflora <strong>and</strong> Lobelia dortmanna<strong>in</strong> southern Sweden. Mycological research 108: 616-625.Ottosen LDM, Risgaard-Petersen N, Nielsen LP. 1999.Direct <strong>and</strong> <strong>in</strong>direct measurements of nitrification <strong>and</strong>denitrification <strong>in</strong> the rhizosphere of aquatic macrophytes.Aquatic Microbial Ecology 19: 81-91.Pedersen O, Andersen T, Ikejima K, Hossa<strong>in</strong> MZ,Andersen FØ. 2006. A multidiscipl<strong>in</strong>ary approach tounderst<strong>and</strong><strong>in</strong>g the recent <strong>and</strong> historical occurrence of thefreshwater <strong>plant</strong>, Littorella uniflora. Freshwater Biology51: 865-877.Pedersen O, S<strong>and</strong>-Jensen K, Revsbech NP. 1995. Dielpulses of O 2 <strong>and</strong> CO 2 <strong>in</strong> s<strong>and</strong>y lake-<strong>sediment</strong>s <strong>in</strong>habitedby Lobelia dortmanna. Ecology 76: 1536–1545.Raun AL, Borum J, S<strong>and</strong>-Jensen K. 2010. Influence of<strong>sediment</strong> organic enrichment <strong>and</strong> water alkal<strong>in</strong>ity ongrowth of aquatic <strong>isoetid</strong> <strong>and</strong> elodeid <strong>plant</strong>s. FreshwaterBiology 55: 1891-1904.Roelofs JGM. 1983. Impact of acidification <strong>and</strong>eutrophication on macrophyte communities <strong>in</strong> soft waters<strong>in</strong> the Netherl<strong>and</strong>s I. Field observations. Aquatic Botany17: 139-155.S<strong>and</strong>-Jensen K, Borum J, B<strong>in</strong>zer T. 2005. <strong>Oxygen</strong>stress <strong>and</strong> reduced growth of Lobelia dortmanna <strong>in</strong> s<strong>and</strong>ylake <strong>sediment</strong>s subject to organic enrichment. FreshwaterBiology 50:1034-1048.S<strong>and</strong>-Jensen K, Pedersen NL, Thorsgaard I, MoeslundB, Borum J, Brodersen KP. 2008. 100 Years ofvegetation decl<strong>in</strong>e <strong>and</strong> recovery <strong>in</strong> Lake Fure, Denmark.Journal of Ecology 96: 260-271S<strong>and</strong>-Jensen K, Prahl C. 1982. <strong>Oxygen</strong> exchange withthe lacunae <strong>and</strong> across leaves <strong>and</strong> roots of the submergedvascular macrophyte, Lobelia dortmanna L. NewPhytologist 91: 103–120.16
IntroductionS<strong>and</strong>-Jensen K, Prahl C, Stokholm H. 1982. <strong>Oxygen</strong>release from roots of submerged aquatic macrophytes.Oikos 50:1034-1048.S<strong>and</strong>-Jensen K, Riis T, Vestergaard O, Larsen S. 2000.Macrophyte decl<strong>in</strong>e <strong>in</strong> Danish lakes <strong>and</strong> streams over thepast 100 years. Journal of Ecology 88:1030-1040.Smith SE, Read DJ. 2008. Mycorrhizal symbiosis.Elsevier Academic Press, San Diego, CA, USA.Smits AJM, Laan P, Thier RH, V<strong>and</strong>ervelde G. 1990.Root aerenchyma, oxygen leakage patterns <strong>and</strong> alcoholicfermentation ability of the roots of some nymphaeid <strong>and</strong><strong>isoetid</strong> macrophytes <strong>in</strong> relation to the <strong>sediment</strong> type oftheir habitat. Aquatic Botany 38: 3–17.Smolders AJP, Lucassen ECTET, Roelofs JGM. 2002.The <strong>isoetid</strong> environment biogeochemistry <strong>and</strong> threats.Aquatic Botany 73: 325-350.Sorrell B. 2004. Regulation of root anaerobiosis <strong>and</strong>carbon translocation by light <strong>and</strong> root aeration <strong>in</strong> Isoetesalp<strong>in</strong>es. Plant, Cell <strong>and</strong> Environment 27:1102-1111.Søndergaard M, Laegaard S. 1977. Vesciculararbuscularmycorrhiza <strong>in</strong> some vascular <strong>plant</strong>s. Nature268: 232-233.Wig<strong>and</strong> C, Andersen FØ, Christensen KK, Holmer M,Jensen HS. 1998. Endomycorrhizae of <strong>isoetid</strong>s along abiogeochemical gradient. Limnology <strong>and</strong> Oceanography43: 508-515.Visser EJW, Colmer TD, Blom CWPM, VoesenekLACJ. 2000. Changes <strong>in</strong> growth, porosity, <strong>and</strong> radialoxygen loss from adventitious roots of selected mono<strong>and</strong>dicotyledonous wetl<strong>and</strong> species with contrast<strong>in</strong>gtypes of aerenchyma. Plant, Cell & Environment 23:1237–1245.Wium-Andersen S, Andersen JM. 1972a. Carbondioxide content of the <strong>in</strong>terstitial water <strong>in</strong> the <strong>sediment</strong> ofGrane Langsø, a Danish Lobelia lake. Limnology <strong>and</strong>Oceanography 17: 943–947.Wium-Andersen S, Andersen JM. 1972b. The <strong>in</strong>fluenceof vegetation on the redox profile of the <strong>sediment</strong> ofGrane Langsø, a Danish Lobelia lake. Limnology <strong>and</strong>Oceanography 17:948-952.17
Change language