effect of changing phosphorus concentrations on algae in headwater streams
TRANSCRIPT
Methods•After inoculation in each stream, tiles were placed in 1 L mesocosm stream water
Beakers incubated at 25°C and light intensity 500 (µE m-2 S-1)•Stream water amended with KH2PO4 to increase DP) or alum (to decrease DP) as required to achieve a range from 0 to 400 µg L-1
•Periphyton biomass (as chlorophyll-a) was determined after 7 days.
BackgroundRecent independent review stated that the U.S. EPA stressor-response approach is the most appropriate, scientifically based method for developing numeric nutrient criteria.It is necessary that algal-response characteristics be determined as a function of in-stream P sources and processing to provide the needed ‘weight-of-evidence’ data for Illinois River Watershed (IRW) streams.
The effect of changing DP concentrations on primary production in Ozark head
water streams
ObjectivesThis study was conducted to examine the effect of increasing and decreasing P concentrations on periphyton biomass in a pristine (Richland Creek) and nutrient enriched (Spring Creek) stream and to determine if hysteresis (past environment and nutrient conditions) had any effect on the response of periphyton.
Raymond Brennan1, Andrew Sharpley1*, Thad Scott1, Brian Haggard2, Mike Bowes3 , Helen Jarvie3
1 Crop, Soil and Environ. Sci. Dept., Division of Agriculture, University of Arkansas, Fayetteville, AR, 2 Arkansas Water Resource Centre, Division of Agriculture, 3 NERC Centre for Ecology and Hydrology, Wallingford, UK. *Presenting author. Contact: [email protected]
ConclusionsAs expected, changing DP increased periphyton biomass. The increase observed followed a similar trend in each stream, however, hysteresis clearly played a role in the magnitude of response. Periphyton accumulation alone does not predict DP concentrations.
4. Increasing soil M3P did not increase periphyton total phosphorus content proportionally once DP exceeded 0.1 mg L-1. The Spring Creek periphyton had a greater capacity to assimilate P.
2. Inoculated tile placed in mesocosm with 500 ml of stream water taken from the same stream as the tile.
1. Unglazed tiles (2 inch square) inoculated for 5 days streams before start of experiment.
3. Increasing DP increased chlorophyll a for periphyton from both streams. Approximately three times more chlorophyll a in Spring Creek.
5. Experiment successfully manipulated stream DP concentrations using KH2PO4 and alum. Biomass accumulation did not increase proportionally once DP exceeded 0.1 mg L-1.
Richland Creek, spring 2012
Spring Creek, spring 2012
0.000 0.050 0.100 0.150 0.200 0.250 0.3000.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
f(x) = 0.303492840957837 ln(x) + 1.63114058536107R² = 0.898629127625143
f(x) = − 45.4711252101199 x² + 21.461782009325 x + 0.530451930537611R² = 0.928365905083105
SpringPolynomial (Spring)RichlandLogarithmic (Richland)Ambient Spring Creek
Dissolved phosphorus (µgL-1)
Chlo
roph
yll a
(µg/
cm-2
)
ParameterRichland Creek
Spring Creek
Dissolved phosphorus (mg L-
1) 0.001 (0.001)0.073 (0.005)
Total phosphorus (mg L-1) 0.016 (0.002)0.088 (0.006)
Nitrate (mg L-1) 0.983 (0.009)3.810 (0.037)
0.000 0.050 0.100 0.150 0.200 0.250 0.3000.000
0.001
0.002
0.003
0.004
0.005
0.006
f(x) = 0.000555626266329343 ln(x) + 0.00310394381815759R² = 0.859614445610381
f(x) = 0.0052444822402271 x^0.267874678148116R² = 0.548728051713905
Spring Creek
Dissolved phosphorus (µgL-1)
Perip
hyto
n to
tal p
hosp
horu
s (m
g cm
-2)