title: Cascading ecological effects of low-level phosphorus enrichment in the Florida everglades.
abstract: Few studies have examined long-term ecological effects of sustained low-level nutrient enhancement on wetland biota. To determine sustained effects of phosphorus (P) addition on Everglades marshes we added P at low levels (5, 15, and 30 microg L(-1) above ambient) for 5 yr to triplicate 100-m flow-through channels in pristine marsh. A cascade of ecological responses occurred in similar sequence among treatments. Although the rate of change increased with dosing level, treatments converged to similar enriched endpoints, characterized most notably by a doubling of plant biomass and elimination of native, calcareous periphyton mats. The full sequence of biological changes occurred without an increase in water total P concentration, which remained near ambient levels until Year 5. This study indicates that Everglades marshes have a near-zero assimilative capacity for P without a state change, that ecosystem responses to enrichment accumulate over time, and that downstream P transport mainly occurs through biota rather than the water column.
authors.affiliation: Southeast Environmental Research Center, Florida International University, Miami, FL 33199, USA. gaisere@fiu.edu
authors.forename: Evelyn E
authors.initials: EE
authors.lastname: Gaiser
authors.forename: Joel C
authors.initials: JC
authors.lastname: Trexler
authors.forename: Jennifer H
authors.initials: JH
authors.lastname: Richards
authors.forename: Daniel L
authors.initials: DL
authors.lastname: Childers
authors.forename: David
authors.initials: D
authors.lastname: Lee
authors.forename: Adrienne L
authors.initials: AL
authors.lastname: Edwards
authors.forename: Leonard J
authors.initials: LJ
authors.lastname: Scinto
authors.forename: Krish
authors.initials: K
authors.lastname: Jayachandran
authors.forename: Gregory B
authors.initials: GB
authors.lastname: Noe
authors.forename: Ronald D
authors.initials: RD
authors.lastname: Jones
mesh_terms: D000818:Animals; D017753:Ecosystem; D005431:Florida; D020387:Food Chain; D010758:Phosphorus / Q000032:analysis* / Q000378:metabolism*; D014867:Water / Q000737:chemistry; D014873:Water Pollutants / Q000032:analysis* / Q000378:metabolism*; D014881:Water Supply
chemical_list: D014873:Water Pollutants; D014867:Water; D010758:Phosphorus