Episodic disturbances drive nutrient dynamics along freshwater‐to‐estuary gradients in a subtropical wetland

Authors

Stephen E. Davis, The Everglades Foundation
Ross Boucek, Bonefish Tarpon Trust
Edward Castaneda-Moya, Department of Biological Sciences and Southeast Environmental Research Center, Florida International UniversityFollow
Shimelis Dessu, Department of Biological Sciences and Southeast Environmental Research Center, Florida International UniversityFollow
Evelyn E. Gaiser, Department of Biological Sciences and Southeast Environmental Research Center, Florida International UniversityFollow
John Kominoski, Department of Biological Sciences and Southeast Environmental Research Center, Florida International UniversityFollow
Jay P. Sah, Department of Biological Sciences and Southeast Environmental Research Center, Florida International UniversityFollow
Donatto Surratt, Everglades National Park
Tiffany Troxler-Gann, Southeast Environmental Research Center and Department of Biological Sciences, Florida International UniversityFollow

Abstract

Wetlands are biogeochemically active ecosystems where primary production and respiration interact with physico‐chemical conditions to influence nutrient availability across spatio‐temporal scales. The effect of episodic disturbances on water quality dynamics within wetlands is relatively unknown, especially in large oligotrophic wetlands such as the Everglades. We describe a range of episodic disturbance events and their impacts on the spatio‐temporal dynamics of surface water total N (TN) and total P (TP) concentrations in the Everglades as a means to understand their effect and legacies. Water quality monitoring along the two principal drainages—Taylor Slough (TS) and Shark River Slough (SRS)—has been ongoing since 2000, spanning myriad disturbances ranging from high‐energy storms such as Hurricane Wilma in 2005 to a record cold event in 2010 and large fires. Local events include pulsed rainfall, low marsh stage, and stage recession and recovery (i.e., droughts and subsequent dry‐to‐wet transitions). The deposition of marine‐derived sediment from Hurricane Wilma corresponded with a doubling of TP in SRS mangrove sites (from 0.39 to 0.84 μmol/L) before recovering to pre‐disturbance mean after 5–6 yr. A brief increase in TP within one week of the 2010 cold event was followed by delayed spikes in TN (>1000 μmol/L) and TN:TP exceeding 5000 after one month. In 2008, a large fire in upper SRS prior to the wet season caused a lagged TP pulse at downstream locations SRS2, SRS3, and possibly SRS4. TP also varied negatively with depth/stage in marsh sites and positively with salinity in estuarine sites, reflecting physical concentration or dilution effects. In upper TS, TP varied according to extremes such as high rainfall and low stage relative to normal conditions. Although excess P in the Everglades is generally derived from anthropogenic upland or natural marine sources, episodic disturbance mobilizes internal sources of nutrients along an Everglades freshwater‐to‐estuary continuum, affecting water quality from days to years depending on disturbance type and intensity. The capacity for resilience is high in coastal wetland ecosystems that are exposed to high‐energy tropical storms and other episodic events, even in the highly managed Florida Everglades.

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This work is licensed under a Creative Commons Attribution 4.0 License.

Comments

Originally published in Ecosphere.

Recommended Citation

Davis, Stephen E.; Boucek, Ross; Castaneda-Moya, Edward; Dessu, Shimelis; Gaiser, Evelyn E.; Kominoski, John; Sah, Jay P.; Surratt, Donatto; and Troxler-Gann, Tiffany, "Episodic disturbances drive nutrient dynamics along freshwater‐to‐estuary gradients in a subtropical wetland" (2018). FCE LTER Journal Articles. 491.
https://digitalcommons.fiu.edu/fce_lter_journal_articles/491