Sheet Flow Effects on Sediment Transport in a Degraded Ridge‐and‐Slough Wetland: Insights Using Molecular Markers

Authors

Peter Regier, Department of Chemistry and Biochemistry and Southeast Environmental Research Center, Florida International University
Ding He, Department of Chemistry and Biochemistry and Southeast Environmental Research Center, Florida International UniversityFollow
Colin J. Saunders, South Florida Water Management District
Blanca Jara, Department of Chemistry and Biochemistry and Southeast Environmental Research Center, Florida International University
Chris Hansen, Department of Chemistry and Biochemistry and Southeast Environmental Research Center, Florida International University
Sue Newman, South Florida Water Management District
Erik Tate-Boldt, South Florida Water Management District
Carlos Coronado-Molina, South Florida Water Management District
Rudolf Jaffe, Department of Chemistry and Biochemistry and Southeast Environmental Research Center, Florida International UniversityFollow

Abstract

Wetland ecosystems are often characterized by self‐organized landscape patterning, driven by abiotic and biotic factors. In the Florida Everglades, natural sheet flow is hypothesized to have distributed sediments to form the pattern of linear emergent ridges and submerged sloughs. Drainage and barriers to flow have degraded these microtopographic features. As part of the Comprehensive Everglades Restoration Plan, the Decompartmentalization Physical Model is a landscape‐scale experiment to evaluate ecosystem responses to restored sheet flow by increasing freshwater inputs and removing barriers to flow. To test the proposed mechanism that flow rebuilds ridge‐slough microtopography by remobilizing slough sediments into ridges, four molecular markers capable of distinguishing ridge, slough, and microbial sources were evaluated in flocculent benthic sediments (floc) and advected sediments (collected in traps) during preflow, high‐flow, and postflow conditions over 4 years. The combined use of the four biomarkers, namely, the aquatic proxy (Paq), C20 highly branched isoprenoids, kaurenes, and botryococcenes, showed compositional patterns that clearly distinguished ridge and slough organic matter. Of these molecular parameters, the Paq was the most reliable in distinguishing among organic matter sources. Long‐term patterns in floc Paq at ridge and slough sites indicate a general increase, indicative of preferential mobilization of slough material. The Paq values for advected sediments are also strongly associated with slough environments, supporting temporal trends in floc samples. Our results tentatively confirm the hypothesis that increased flow in degraded ridge‐and‐slough wetlands, and associated sediment transport, is a potentially viable mechanism to restore historic patterns of microtopography.

Comments

Originally published in JGR Biogeosciences.

Recommended Citation

Regier, Peter; He, Ding; Saunders, Colin J.; Jara, Blanca; Hansen, Chris; Newman, Sue; Tate-Boldt, Erik; Coronado-Molina, Carlos; and Jaffe, Rudolf, "Sheet Flow Effects on Sediment Transport in a Degraded Ridge‐and‐Slough Wetland: Insights Using Molecular Markers" (2018). FCE LTER Journal Articles. 516.
https://digitalcommons.fiu.edu/fce_lter_journal_articles/516