Nutrient Controls on Biocomplexity of Mangrove Ecosystems
Nutrient Controls on Biocomplexity of Mangrove Ecosystems
Nutrient Controls on Biocomplexity of Mangrove Ecosystems
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<str<strong>on</strong>g>Nutrient</str<strong>on</strong>g> <str<strong>on</strong>g>C<strong>on</strong>trols</str<strong>on</strong>g> <strong>on</strong> <strong>Biocomplexity</strong> <strong>of</strong> <strong>Mangrove</strong> <strong>Ecosystems</strong><strong>Mangrove</strong> <strong>Ecosystems</strong><strong>Mangrove</strong> forests are important coastal ecosystems thatprovide a variety <strong>of</strong> ecological and societal services. Theseintertidal, tree-dominated communities al<strong>on</strong>g tropical coastlinesare <strong>of</strong>ten described as “simple systems,” compared to othertropical forests with larger numbers <strong>of</strong> plant species andmultiple understory strata; however, mangrove ecosystemshave complex trophic structures, and organisms exhibit uniquephysiological, morphological, and behavioral adaptati<strong>on</strong>sto envir<strong>on</strong>mental c<strong>on</strong>diti<strong>on</strong>s characteristic <strong>of</strong> the land-seainterface. Biogeochemical functi<strong>on</strong>ing <strong>of</strong> mangrove forestsis also c<strong>on</strong>trolled by interacti<strong>on</strong>s am<strong>on</strong>g the microbial, plant,and animal communities and feedback linkages mediated byhydrology and other forcing functi<strong>on</strong>s. Scientists with the U.S.Geological Survey (USGS) at the Nati<strong>on</strong>al Wetlands ResearchCenter are working to understand more fully the impact <strong>of</strong>nutrient variability <strong>on</strong> these delicate and important ecosystems.Worldwide, there are about 50 mangrove species, but speciesrichness in any particular forest stand may vary. In Florida andthe Caribbean regi<strong>on</strong>, the most comm<strong>on</strong> species is Rhizophoramangle (red mangrove) (fig.1), which typically dominates theshorelines <strong>of</strong> islands and low-lying regi<strong>on</strong>s al<strong>on</strong>g c<strong>on</strong>tinentalmargins. Red mangrove may occur with two other species;Avicennia germinans (black mangrove), and Lagunculariaracemosa (white mangrove), in additi<strong>on</strong> to a number <strong>of</strong>mangrove associates such as C<strong>on</strong>ocarpus erectus (butt<strong>on</strong>mangrove) and Batis maritima (maritime saltwort). In the Indo-West Pacific realm, forests may have over 30 mangrove speciesplus additi<strong>on</strong>al numbers <strong>of</strong> associates. Some mangrove forestsmay exhibit low structural complexity, but others may c<strong>on</strong>tain avariety <strong>of</strong> forbs, ferns, vines, and epiphytes such as orchidsand bromeliads.What is <strong>Biocomplexity</strong>?The study <strong>of</strong> biocomplexity is a rapidly developing area <strong>of</strong>research that seeks to better understand the emergent properties<strong>of</strong> ecosystems and how they may be affected as underlyingmechanisms or external forcing functi<strong>on</strong>s change. Habitatstability is an emergent property <strong>of</strong> ecosystems that arisesas a c<strong>on</strong>sequence <strong>of</strong> many processes interacting at differentspatio-temporal scales and at different levels <strong>of</strong> biologicalorganizati<strong>on</strong>. For mangroves, habitat stability is primarilyRhizophora mangle (red mangrove) Avicennia germinans (black mangrove) Laguncularia racemosa (white mangrove)Figure 1.Dominant mangrove species occurring in Florida and the Caribbean regi<strong>on</strong>.U.S. Department <strong>of</strong> the InteriorU.S. Geological SurveyFact Sheet 2004-3124March 2006
whole—even destabilizing the delicate balance between bioticand abiotic processes c<strong>on</strong>trolling soil elevati<strong>on</strong>s and habitatstability in peat-forming mangroves.A global comparis<strong>on</strong> <strong>of</strong> nutrient limitati<strong>on</strong>s to mangrove growthis essential to an understanding <strong>of</strong> how coastal eutrophicati<strong>on</strong>may impact these important ecosystems—in the United States,as well as in other countries. Collaborati<strong>on</strong> between theUSGS and the Smiths<strong>on</strong>ian Envir<strong>on</strong>mental Research Center inEdgewater, Maryland has led to the establishment <strong>of</strong> multipleexperimental sites in mangrove forests located in Florida,Louisiana, Belize, H<strong>on</strong>duras, Panama, Australia, and NewZealand (fig. 3). Research in different geographic areas will leadto more accurate models to predict global change impacts <strong>on</strong>mangrove ecosystems and better management plans fortheir c<strong>on</strong>servati<strong>on</strong>.References CitedFeller, I.C., McKee, K.L., Whigham, D.F., and O’Neill, J.P., 2003,Nitrogen vs phosphorus limitati<strong>on</strong> across an ecot<strong>on</strong>al gradient in amangrove forest: Biogeochemistry, v. 62, p. 145-175.Feller, I.C., Whigham,D.F., McKee, K.L., and Lovelock, C.E., 2003,Nitrogen limitati<strong>on</strong> <strong>of</strong> growth and nutrient dynamics in a disturbedmangrove forest, Indian River Lago<strong>on</strong>, Florida: Oecologia, v. 134,no. 3, p. 405-414.McKee, K.L., Feller, I.C., Popp, M., and Wanek,W., 2002, <strong>Mangrove</strong>isotopic fracti<strong>on</strong>ati<strong>on</strong> (δ 15 N and δ 13 C) across a nitrogen versusphosphorus limitati<strong>on</strong> gradient; Ecology, v. 83, no. 4, p. 1065-1075.For more informati<strong>on</strong>, c<strong>on</strong>tactKaren L. McKeeU.S. Geological SurveyNati<strong>on</strong>al Wetlands Research Center700 Cajundome Blvd.Lafayette, LA 70506337-266-8500http://www.nwrc.usgs.govRookery Bay,Florida, USAIndian River Lago<strong>on</strong>,Florida, USAPort Douglas, AustraliaPort Fourch<strong>on</strong>,Louisiana, USAHinchinbrook, AustraliaTwin Cays, BelizeCape Fergus<strong>on</strong>, AustraliaBay Island & Gulf <strong>of</strong> F<strong>on</strong>seca,H<strong>on</strong>durasBocas del Toro, PanamaWaikopua Creek,New ZealandFigure 3. Locati<strong>on</strong> <strong>of</strong> multiple experimental sites where USGS scientists are studying nutrient c<strong>on</strong>trols <strong>on</strong> mangroveecosystem structure and functi<strong>on</strong>.