Abstract
Nutrient and algae data were collected in the 1990s and
2000s by the U.S. Geological Survey for the National Water-
Quality Assessment program in the Ozark Highlands, southern
Missouri. These data were collected at sites of differing drainage
area, land use, nutrient concentrations, and physiography.
All samples were collected at sites with a riffle/pool structure
and cobble/gravel bed material. A total of 60 samples from
45 sites were available for analyses to determine relations
between nutrient concentrations and algal community structure
in this region. This information can be used by the Missouri
Department of Natural Resources to develop the State’s nutrient
criteria plan. Water samples collected for this study had
total nitrogen concentrations ranging from 0.07 to 4.41 milligram
per liter (mg/L) with a median of 0.26 mg/L, and total
phosphorus concentrations ranging from 0.003 to 0.78 mg/L
with a median of 0.007 mg/L. These nutrient concentrations
were transformed into nutrient categories consisting of varying
percentiles of data. Algal community data were entered into
the U.S. Geological Survey’s Algae Data Analysis System for
the computation of more than 250 metrics. These metrics were
correlated with nutrient categories, and four metrics with the
strongest relation with the nutrient data were selected. These
metrics were Organic Nitrogen Tolerance, Oxygen Tolerance,
Bahls Pollution Class, and the Saprobien index with the 25th
and 80th percentile nutrient categories. These data indicate
that near the 80th percentile (Total Nitrogen = 0.84 mg/L,
Total Phosphorus = 0.035 mg/L) the algae communities significantly
changed from nitrogen-fixing species dominance to
those species more tolerant of eutrophic conditions.
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First posted March 20, 2012
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