El Niño Southern Oscillation (ENSO) enhances CO2 exchange rates in freshwater Marsh ecosystems in the Florida everglades

PLoS One. 2014 Dec 18;9(12):e115058. doi: 10.1371/journal.pone.0115058. eCollection 2014.


This research examines the relationships between El Niño Southern Oscillation (ENSO), water level, precipitation patterns and carbon dioxide (CO2) exchange rates in the freshwater wetland ecosystems of the Florida Everglades. Data was obtained over a 5-year study period (2009-2013) from two freshwater marsh sites located in Everglades National Park that differ in hydrology. At the short-hydroperiod site (Taylor Slough; TS) and the long-hydroperiod site (Shark River Slough; SRS) fluctuations in precipitation patterns occurred with changes in ENSO phase, suggesting that extreme ENSO phases alter Everglades hydrology which is known to have a substantial influence on ecosystem carbon dynamics. Variations in both ENSO phase and annual net CO2 exchange rates co-occurred with changes in wet and dry season length and intensity. Combined with site-specific seasonality in CO2 exchanges rates, El Niño and La Niña phases magnified season intensity and CO2 exchange rates at both sites. At TS, net CO2 uptake rates were higher in the dry season, whereas SRS had greater rates of carbon sequestration during the wet season. As La Niña phases were concurrent with drought years and extended dry seasons, TS became a greater sink for CO2 on an annual basis (-11 to -110 g CO2 m-2 yr-1) compared to El Niño and neutral years (-5 to -43.5 g CO2 m-2 yr-1). SRS was a small source for CO2 annually (1.81 to 80 g CO2 m-2 yr-1) except in one exceptionally wet year that was associated with an El Niño phase (-16 g CO2 m-2 yr-1). Considering that future climate predictions suggest a higher frequency and intensity in El Niño and La Niña phases, these results indicate that changes in extreme ENSO phases will significantly alter CO2 dynamics in the Florida Everglades.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Carbon Dioxide / analysis*
  • Climatic Processes*
  • Florida
  • Fresh Water / chemistry
  • Hydrology
  • Wetlands*


  • Carbon Dioxide

Grant support

Funding for the research was provided by the National Science Foundations (NSF) Division of Atmospheric and Geospace Sciences (AGS) Atmospheric Chemistry program through grant 1233006 [GS SFO], the Department of Energy's (DOE) National Institute for Climate Change Research (NICCR) through grant 07-SC-NICCR-1059 [GS SFO], and the US Department of Education Graduate Assistantships in Areas of National Need (GAANN) grant [SLM]. This research was also supported by the National Science Foundation (NSF) through the Florida Coastal Everglades Long Term Ecological Research program under Cooperative Agreements DBI-0620409 and DEB-9910514 [GS SFO]. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.