MICROBIAL COMMUNITY PATTERNS ALONG A VEGETATION AND SALINITY GRADIENT IN MOBILE BAY ESTUARY, AL, USA: IMPLICATIONS FOR WETLAND ECOSYSTEM FUNCTIONS

Tidal wetlands host biodiversity, serve as barriers to storm surge, and are integral regulators of nitrogen, phosphorus, and sulfur cycling. Estuaries are critical to carbon storage and greenhouse gas production, balancing mineralization and burial of organic matter. We describe soil physicochemical and microbial diversity along a vegetation and salinity gradient in the Mobile Bay estuary, AL, USA – the sixth largest watershed in the US – and discuss how these factors feedback on ecosystem characteristics and the delivery of ecological functions. We incorporated microbial trait data including biomass, diversity, community composition, and inferred functions into patterns of coastal vegetation occurrence, salinity, sediment C/N/P/S content, and extracellular enzyme activities spanning the organic and mineral soil horizons. Modeling these parameters showed that vegetation type >> soil horizon > and salinity strongly influenced microbe-soil relationships. All biotic and abiotic factors indicated that tidal freshwater forested wetlands represent a distinct biome within the Mobile Bay estuary, distinct from zonation of increasingly salt-tolerant Typha, tidal shrub, and Juncus, which are considered “emergent marsh”. Forested wetlands contained 80% less organic carbon content, 75% less nitrogen, 33% less phosphorus, and 95% less sulfur than emergent marsh, correlating closely with a unique microbial community. Integration of biological diversity, enzymatic, and geochemical data layers are important steps to incorporating microbial trait data into soil carbon models in wetlands.

Primary Presenter: Eric Weingarten, U.S. Army Engineer Research and Development Center (microbialdiveric@gmail.com)

Authors:

Carina Jung, U.S. Army Engineer Research and Development Center  (carina.m.jung@usace.army.mil)

Fiona Crocker, U.S. Army Engineer Research and Development Center  (fiona.h.crocker@usace.army.mil)

Marissa Kneer, U.S. Army Engineer Research and Development Center  (marissa.l.kneer@usace.army.mil)

Nia Hurst, U.S. Army Engineer Research and Development Center  (nia.r.hurst@usace.army.mil)

Mark Chappell, U.S. Army Engineer Research and Development Center  (mark.a.chappell@usace.army.mil)

Jacob Berkowitz, U.S. Army Engineer Research and Development Center  (jacob.f.berkowitz@usace.army.mil)

Karl Indest, U.S. Army Engineer Research and Development Center  (karl.j.indest@usace.army.mil)