Diel oxygen profiles and water column community metabolism in the Florida Everglades, U.S.A. fig: 5 tab: 1
McCormick, Paul V.; Chimney, Michael J.; Swift, David R.
Archiv für Hydrobiologie Volume 140 Number 1 (1997), p. 117 - 129
published: Aug 13, 1997
ArtNo. ESP141014001008, Price: 29.00 €
A variety of ecosystem-level changes observed in the Florida Everglades during this century has been attributed to anthropogenic phosphorus inputs to the system. Diel oxygen profiles were measured periodically at three reference (minimal nutrient impact) sites in the Everglades between 1979 and 1985 to characterize background patterns of oxygen availability and community metabolism within the marsh. Oxygen profiles were also measured at a nutrient-enriched site to evaluate relative changes in water column primary productivity associated with increased phosphorus loading. Strong diel variations in water column oxygen concentration (0-12 mg 1-1) were recorded at all reference sites, whereas oxygen concentrations rarely exceeded 2 mg 1-1 at the enriched site and were often undetectable. Rates of gross primary productivity and aerobic respiration within the water column were higher, with average P/R ratios near unity, at reference sites than at the enriched site (P/R <0.5). Nutrient enrichment was associated with reduced periphyton productivity, a shift towards increasing community heterotrophy, and protracted periods of oxygen depletion.