title: Potential for Sulfate Reduction in Mangrove Forest Soils: Comparison between Two Dominant Species of the Americas.
abstract: AvicenniaandRhizophoraare globally occurring mangrove genera with different traits that place them in different parts of the intertidal zone. It is generally accepted that the oxidizing capacity ofAvicenniaroots is larger than that ofRhizophoraroots, which initiates more reduced conditions in the soil below the latter genus. We hypothesize that the more reduced conditions beneathRhizophorastands lead to more active sulfate-reducing microbial communities compared toAvicenniastands. To test this hypothesis, we measured sulfate reduction traits in soil samples collected from neighboringAvicennia germinansandRhizophora manglestands at three different locations in southern Florida. The traits measured were sulfate reduction rates (SRR) in flow-through reactors containing undisturbed soil layers in the absence and presence of easily degradable carbon compounds, copy numbers of thedsrBgene, which is specific for sulfate-reducing microorganisms, and numbers of sulfate-reducing cells that are able to grow in liquid medium on a mixture of acetate, propionate and lactate as electron donors. At the tidal locations Port of the Islands and South Hutchinson Islands, steady state SRR,dsrBgene copy numbers and numbers of culturable cells were higher at theA. germinansthan at theR. manglestands, although not significantly for the numbers at Port of the Islands. At the non-tidal location North Hutchinson Island, results are mixed with respect to these sulfate reduction traits. At all locations, the fraction of culturable cells were significantly higher at theR. manglethan at theA. germinansstands. The dynamics of the initial SRR implied a morein situactive sulfate-reducing community at the intertidalR. manglestands. It was concluded that in agreement with our hypothesisR. manglestands accommodate a more active sulfate-reducing community thanA. germinansstands, but only at the tidal locations. The differences betweenR. mangleandA. germinansstands were absent at the non-tidal, impounded location.
authors.affiliation: Department of Microbial Ecology, Netherlands Institute of Ecology-Royal Netherlands Academy of Arts and SciencesWageningen, Netherlands; Faculty of Geosciences, Utrecht UniversityUtrecht, Netherlands.
authors.forename: Melike
authors.initials: M
authors.lastname: Balk
authors.affiliation: Department of Microbial Ecology, Netherlands Institute of Ecology-Royal Netherlands Academy of Arts and SciencesWageningen, Netherlands; Ecology and Biodiversity Group, Department of Biology, Utrecht UniversityUtrecht, Netherlands.
authors.forename: Joost A
authors.initials: JA
authors.lastname: Keuskamp
authors.affiliation: Department of Microbial Ecology, Netherlands Institute of Ecology-Royal Netherlands Academy of Arts and SciencesWageningen, Netherlands; Ecology and Biodiversity Group, Department of Biology, Utrecht UniversityUtrecht, Netherlands.
authors.forename: Hendrikus J
authors.initials: HJ
authors.lastname: Laanbroek
keywords: Avicennia germinans; Rhizophora mangle; dsrB gene; mangroves; sulfate reduction