Water Quality Sampling
of the Skidaway River Estuary
Verity (Skidaway Inst. of Oceanography, Savannah, Georgia, USA)
The National Science Foundation, Department of Energy, and Georgia Sea Grant
College Program all provided general support during the project period, although
the sampling program was not a grant-funded project.
1986 - ongoing
Starting in 1986, samples were taken at weekly intervals, at high and low tide
on the same day at a single site from the waters adjacent to the docks at the
Skidaway Institute of Oceanography. Hydrography, nutrients, chlorophyll
a, particulate matter, and microbial and plankton biomass and composition
- Salinity varied
inversely with river discharge and exhibited variability at all time scales,
but with no long-term trend.
- Water temperature
ranged over 25 degrees C, and was without apparent long-term trend.
- Seasonal cycles
in concentrations of NO3, NH4, PO4, Si(OH)4 and DON were observed, with annual
maxima generally occurring in late summer.
on seasonal cycles, all five nutrients exhibited steady increases in minimum,
mean, and maximum concentrations; mean concentrations increased c. 50-150%
during the decade.
- Nutrient concentrations
were highly correlated with water temperature over the 10-year period, but
weakly related to salinity and discharge.
- Nutrients were
strongly correlated with one another, and the relative ratios among inorganic
nutrients showed little long-term trend.
among temperature and nutrient concentration exhibited considerable inter-annual
- Major spikes
in organic and inorganic nutrient concentrations coincided with significant
- All classes
of particulate organic matter exhibited distinct seasonal patterns superimposed
upon significant long-term increases during the study period.
- Chl a
increased 18-61% over ten years (depending on size fraction).
organic carbon and nitrogen increased 16% over the decade, and exhibited increases
in annual amplitude.
- The C:N ratio
was typically 6.4-6.6 (wt:wt) and did not change significatntly, while the
annual mean C:Chl a ratio decreased 19% from 165 to 140.
explained 45-50% of the variance in particulate organic matter.
- Ambient concentrations
of dissolved organic nitrogen or PO4 explained 60-75% of the variance in chl
a, and particulate organic carbon and nitrogen.
- These data
strongly suggest that anthropogenic activities contributed to increased loading
of dissolved nutrients, which became incorporated into living and nonliving
P.G. 2002. A decade of change in the Skidaway River Estuary. I. Hydrography
and nutrients. Estuaries 25(5): 944-960.
P.G. 2002. A decade of change in the Skidaway River Estuary. II. Particulate
organic carbon, nitrogen, and chlorophyll a. Estuaries 25(5): 961-975.