title: Effects of increased summer flooding on nitrogen dynamics in impounded mangroves.
abstract: Mangroves are important for coastal protection, carbon sequestration and habitat provision for plants and animals in the tropics and subtropics. Mangroves are threatened by habitat destruction and sea level rise, but management activities such as impounding for mosquito control can also have negative effects. We studied the effects of Rotational Impoundment Management (RIM) on nitrogen dynamics in impoundments dominated by three types of Black mangrove (Avicennia germinans) stands along the Indian River Lagoon (Florida). RIM, designed for noxious insect control, involves pumping estuarine water into impoundments in this area during spring and summer to raise water levels by 30 cm. We compared aspects of the nitrogen cycle before and after the start of the RIM and measured the same variables in an impoundment without RIM management. RIM led to the accumulation of ammonium in the substrate which coincided with a lowering of nitrification rates and decreased denitrification rates. Salt pan habitats dominated by dwarf mangroves became less saline following RIM initiation. Shoot growth of mangroves increased in response to higher nitrogen availability and lower pore water salinity. Mangrove responses were greatest in areas with dwarf and sparse mangrove cover. Overall, RIM resulted in lower nitrification and denitrification leading to lower nitrogen losses and increased Black mangrove growth, all benefits of RIM beyond those associated with noxious insect control.
authors.affiliation: Ecology and Biodiversity, Institute of Environmental Biology, Utrecht University, Padualaan 8, 3584 CH Utrecht, The Netherlands; Smithsonian Environmental Research Center, P.O. Box 23, Edgewater, MA 21037, USA. Electronic address: j.t.a.verhoeven@uu.nl.
authors.forename: Jos T A
authors.initials: JT
authors.lastname: Verhoeven
authors.affiliation: Ecology and Biodiversity, Institute of Environmental Biology, Utrecht University, Padualaan 8, 3584 CH Utrecht, The Netherlands; Smithsonian Environmental Research Center, P.O. Box 23, Edgewater, MA 21037, USA; Department of Microbial Ecology, Netherlands Institute of Ecology (NIOO-KNAW), P.O. Box 50, 6700 AB Wageningen, The Netherlands. Electronic address: r.laanbroek@nioo.knaw.nl.
authors.forename: Hendrikus J
authors.initials: HJ
authors.lastname: Laanbroek
authors.affiliation: School of Geosciences, University of South Florida, 4202 East Fowler Ave, SCA528 Tampa, FL 33620, USA. Electronic address: mrains@usf.edu.
authors.forename: Mark C
authors.initials: MC
authors.lastname: Rains
authors.affiliation: Smithsonian Environmental Research Center, P.O. Box 23, Edgewater, MA 21037, USA. Electronic address: whighamd@si.edu.
authors.forename: Dennis F
authors.initials: DF
authors.lastname: Whigham
mesh_terms: D064751:Ammonium Compounds / Q000032:analysis; D032407:Avicennia / Q000254:growth & development*; D017753:Ecosystem; D005431:Florida; D007300:Insect Control / Q000379:methods*; D009584:Nitrogen / Q000032:analysis; D058458:Nitrogen Cycle; D012621:Seasons; D053833:Wetlands
chemical_list: D064751:Ammonium Compounds; D009584:Nitrogen
keywords: Avicennia; Hydroperiod; Mangrove; Mosquito control; Nitrogen cycling; Water management