Gj. Nicholson et Ar. Longmore, Causes of observed temporal variability of nutrient fluxes from a southernAustralian marine embayment, MAR FRESH R, 50(6), 1999, pp. 581-588
Benthic chambers were used to measure temporal differences of sediment-wate
r column flux of dissolved oxygen (DO), ammonium, nitrite plus nitrate, pho
sphate, silicate and total carbon dioxide (TCO2) in Port Phillip Bay. Three
clear and three dark benthic chambers were deployed between October 1994 a
nd January 1996 at each of three sites: near the outflow of a major sewage
treatment plant, near the mouth of a river and in the deep centre of the ba
y. Analysis of variance indicated that chamber type did not significantly a
ffect magnitude of flux for the majority of deployments. Water temperature
at the time of deployment had a significant effect on the fluxes of DO, TCO
2, NH4, and SiO4 at the central bay site and for all fluxes at the other tw
o sites. There was a relationship between TCO2 flux in the sediment and C p
roduction in the water column (r(2) = 0.6552). The denitrification efficien
cy at the central bay site was usually >80% at all times, and altered by si
milar to 30% seasonally at the other two sites. It is likely that the effec
t of water temperature on a suite of biological processes is the predominan
t source of temporal variation in these benthic fluxes.