COS 23-7 - Restoring ecosystem function in the P-enriched Everglades: Creating an alternate regime

Tuesday, August 9, 2016: 9:50 AM
Floridian Blrm A, Ft Lauderdale Convention Center
Sue Newman1, Mark Cook1, Michael Manna1 and Scot Hagerthey2, (1)Everglades Systems Assessment, South Florida Water Management District, West Palm Beach, FL, (2)National Center for Environmental Assessment, U.S. EPA, Washington, DC

Four decades of elevated phosphorus (P) loads to the historically oligotrophic Everglades has resulted in a regime shift from the ridge (Cladium jamaicense Crantz)-and-slough landscape to large areal expanses of cattail (Typha domingensis Pers.).  To accelerate the recovery of P-impacted areas, restoration requires not only a reduction in the external P concentrations and loads, but also management activities that reduce the internal resilience and resistance inherent to the cattail regime. The cattail habitat improvement project (CHIP) is a large-scale in situ study comprised of 15 6.25 ha plots to test the ability to rehabilitate cattail areas by creating an alternative submerged aquatic vegetation (SAV) regime.

Using a combination of herbicides and fire, open areas were created in enriched and moderately enriched areas of the northern Everglades (Water Conservation Area-2A).  The two primary objectives were to assess whether creating openings in dense cattail areas sufficiently altered trophic dynamics such that wildlife diversity and abundance increased and, to what extent the ecological functions of these created open areas compared to those of the natural Everglades. 


Within weeks to months there was strong evidence of altered ecological function within the open plots relative to controls with; 1) increased dissolved oxygen concentrations, 2) increased microbial activity and associated decomposition, 3) extensive SAV, principally Chara cover, and 4) increased fish abundance.  Direct evidence of connections between altered nutrient cycling and foodweb dynamics were assessed using stoichiometric relationships.  Stoichiometric relationships indicated that the quality, quantity, and diversity of primary consumers were greater in open plots relative to controls.  In addition, because the active management strategy removed dense emergent macrophytes the higher quality prey were more readily accessible for consumption by wading birds.   A principal concern of the project was active management could exacerbate P issues in this already enriched landscape. During the first four years, floc P levels were elevated in open versus control plots, more recently, P concentrations have decreased and indicate P is being stored differently in potentially a less available form. Ten years since project initiation, it appears that with minimal effort and cost, the ecological benefits of this altered regime could be sustained in the long-term.