Spatial and temporal patterns and ecological effects of canal-water intrusion into the A.R.M. Loxahatchee National Wildlife Refuge

Project Investigators: Paul McCormick, William H. Orem Project Personnel: Judson Harvey Project Start Date: 2004 End Date: 2007 Recent Funding: (FY07) USGS GE PES, USGS/BRD, (FY06) USGS GE PES, (FY05) USGS GE PES Work Plans Project Summaries Publications

Summary

The purpose of this study is to understand causes and predict patterns of canal-water intrusion and to assess effects on sensitive wetland biota and functions.

Alterations to groundwater and surface-water hydrology and water chemistry in south Florida have contributed to increased flows of mineral-rich (i.e., high conductivity) canal water into historically rainfall-driven (low conductivity) areas of the Everglades. The Loxahatchee National Wildlife Refuge has largely retained its historic low conductivity or “soft-water” condition, which supports a characteristic periphyton community, wetland plant species that may also be adapted to soft-water conditions, and lower rates of key ecosystem processes (e.g., decomposition) than in areas of the Everglades exposed to canal discharges. Recent monitoring data indicate a trend towards increased intrusion of canal water into the Refuge interior, but the causes (e.g., changing water management strategies, weather patterns) and magnitude of ecological effects resulting from this intrusion are not clear.

This study is part of a coordinated effort between USGS and the Refuge to understand causes and predict patterns of canal-water intrusion and to assess effects on sensitive wetland biota and functions. Synoptic surveys, monitoring along canal-water gradients, and field experimentation were initiated in FY04 with the following objectives:

(1) document spatial and temporal patterns of canal-water intrusion into the Refuge;
(2) quantify nutrient concentrations and shifts in the nature and degree of nutrient limitation along canal-water gradients;
(3) quantify changes in key microbial, periphyton, and plant processes along these gradients;
(4) link changes in biota and process rates to water chemistry changes caused by canal-water intrusion through field experimentation.

Work Plans

• 2005
• 2006
• 2007

Project Summaries

• 2004
• 2005
• 2006

Publications

Abstracts

• Vegetation Responses to Mineral Gradients in an Ombrotrophic Northern Everglades Peatland, the Arthur R. Marshall Loxahatchee National Wildlife Refuge (from the GEER Conference, June 2006)