Cascading ecological effects of low-level phosphorus enrichment in the Florida everglades.
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.
Gaiser
Evelyn E
EE
Southeast Environmental Research Center, Florida International University, Miami, FL 33199, USA. gaisere@fiu.edu
Trexler
Joel C
JC
Richards
Jennifer H
JH
Childers
Daniel L
DL
Lee
David
D
Edwards
Adrienne L
AL
Scinto
Leonard J
LJ
Jayachandran
Krish
K
Noe
Gregory B
GB
Jones
Ronald D
RD
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
D014873:Water Pollutants; D014867:Water; D010758:Phosphorus