Eutrophication of the Salt River Reservoirs due to the Rodeo-
Chedeski Fire.
Nutrient Loading into Roosevelt
Summer 02
Fall 02
Winter 02/03
Spring 03
Summer 03
Fall 03
Winter 04
Spring 04
Summer 04
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Y
Mean(Ammonia_N_mgPerL_asN)
Mean(NitrateNitrite_N_ppm)
Mean(Total_P_ppm)
Mean(Total_Kjeldahl_Nitrogen_mgPerl_as_N
TOC/DOC in the Salt River above Roosevelt
Summer 02
Fall 02
Winter 02/03
Spring 03
Summer 03
Fall 03
Winter 04
Spring 04
Summer 04
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OverlayChart
Y
Mean(TOC_ppm)
Mean(DOC_ppm)
Chart
Summer Nutrient Levels from Roosevelt (mean for all sites)
Summer 02
Summer 03
Summer 04
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Y
Mean(Ammonia_N_mgPerL_asN)
Mean(NitrateNitrite_N_ppm)
Mean(Total_P_ppm)
Mean(Total_Kjeldahl_Nitrogen_mgPe
0
0.1
0.4
0.5
0.6
Summer 02 Summer 03 Summer 04
Sampling_Period
All PairsTukey-Kramer 0.05
RsquareAdj RsquareRoot Mean Square ErrorMean of ResponseObservations (or Sum Wgts)
0.7677160.7587820.0562880.189455
55
Summary of Fit
Sampling_PeriodErrorC. Total
Source 2 52 54
DF0.544528190.164755440.70928364
Sum of Squares0.2722640.003168
Mean Square 85.9318
F Ratio <.0001Prob > F
Analysis of Variance
Summer 02Summer 03Summer 04
Level 13 27 15
Number0.3569230.1674070.084000
Mean0.015610.010830.01453
Std Error0.325600.145670.05484
Lower 95%0.388250.189140.11316
Upper 95%
Std Error uses a pooled estimate of error variance
Means for Oneway Anova
Oneway Anova
Oneway Analysis of DO_mg_per_L By Sampling_Period
DO
_mg_
per_
L0.2
0.3
Components:Chl_a_mgPerm3DOC_ppmTOC_ppmAmmonia_N_mgPerL_asNNitrateNitrite_N_ppmTotal_P_ppmTotal_Kjeldahl_Nitrogen_mgPerl_Prin Comp 1 Prin Comp 2 Prin Comp 3 Prin Comp 4 Prin Comp 5 Prin Comp 6 Prin Comp 7
Chl_a_m
DOC_ppm
TOC_ppm
Ammonia
Nitrate
Total_P
Total_K
x
y
z
Spinning Plot
PCA of Primary Production in Roosevelt
Mean Hypolimnetic DO Levels by Reservoir
DO
_mg_
per_
L
0
1
2
3
4
5
Apache Canyon Roosevelt Saguaro
Reservoir
RsquareAdj RsquareRoot Mean Square ErrorMean of ResponseObservations (or Sum Wgts)
0.0220820.009755 1.078820.719421
242
Summary of Fit
ReservoirErrorC. Total
Source 3
238 241
DF 6.25467
276.99705 283.25172
Sum of Squares 2.08489 1.16385
Mean Square 1.7914F Ratio
0.1495Prob > F
Analysis of Variance
ApacheCanyonRooseveltSaguaro
Level 105 13 58 66
Number 0.73124 1.10077 0.476900.83864
Mean0.105280.299210.141660.13279
Std Error0.523830.511330.197840.57704
Lower 95% 0.9386 1.6902 0.7560 1.1002
Upper 95%
Means for Oneway Anova
Oneway Anova
Mean Summer Hypolimnetic DO Levels for all Salt River Reservoirs by Year
Summer 02
Summer 03
Summer 04
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.0 .1 .2 .3 .4 .5 .6 .7 .8 .9 1.0Mean(DO_mg_per_L)
Sampling_Period Summer 02 Summer 03 Summer 04
Chart
PCA of Primary Production in Apache,
Canyon, and Saguaro
Components:Chl_a_mgPerm3DOC_ppmTOC_ppmAmmonia_N_mgPerL_asNNitrateNitrite_N_ppmTotal_P_ppmTotal_Kjeldahl_Nitrogen_mgPerl_Prin Comp 1 Prin Comp 2 Prin Comp 3 Prin Comp 4 Prin Comp 5 Prin Comp 6 Prin Comp 7
Chl_a_m
DOC_ppm
TOC_ppm
Ammonia
Nitrate
Total_P
Total_K
x
y
z
Spinning Plot
Mean Chlorophyll a values for Apache, Canyon, and Saguaro Reservoirs by Season and Year
Summer 02
Fall 02
Winter 02/03
Spring 03
Summer 03
Fall 03
Winter 04
Spring 04
Summer 04
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0 10Mean(Chl_a_mgPerm3)
• Autochthonous processes within the reservoirs may mean eutrophication proceeds unabated long after nutrient loading via the Salt River has diminished.
• This will have consequences, some severe and others subtle, on water quality entering the Valley for some years to come.
Algal Toxins in the Salt River Reservoirs
• We routinely sample for anatoxin-a, microcystin, and cylindrospermopsin.
• We first discovered C. raciborskii in Arizona in 2001.
• Numbers have increased in all reservoirs surrounding the Valley since that time
Analytical Methods• Anatoxin-a, Saxitoxin
– HPLC after fluorescent derivatization.
• Microcystin– Protein phosphatase inhibition assay.
• If greater than 0.5 µg/L, confirmed byHPLC using a PDA detector.
• Cylindrospermopsin– HPLC using a photodiode array detector
• Detection limit for all assays is less than 0.1 µg/L
Fish Kills• First major fish kill occurred in Apache
in March of 2004. • Subsequent fish kills occurred in
Canyon, Saguaro, and again in Apache throughout the spring and early summer.
• Multiple species involved.• All water quality variables were
“normal”
• A major fish kill occurred in the riverine portion of Saguaro on 6/10/04.
• Smaller fish (e.g., threadfin shad) were noticed dead or moribund in Canyon on 6/9/04.
• Relatively large background levels of microcystin in all watersheds.
• Etiology of the fish kills implicate a fast-acting neurotoxin such as anatoxin-a.
• While levels of C. raciborskiisteadily rose throughout the summer of 2004, only very low levels of cylindrospermopsin have been found.
Persistence/Degradation ofToxins
• Both cylindrospermopsin and microsystin are environmentally stable compounds.
• Anatoxin-a, however, is rapidly degraded by sunlight and alkaline conditions with a half life of perhaps only a few hours.
Anatoxin-a• Potent neurotoxin which causes
rapid death by respiratory arrest.• Postsynaptic, depolarising,
neuromuscular, blocking agent that binds strongly to the nicotinic acetylcholine receptor.
• Produced by species of Anabaena, Aphanizomenon, Oscillatoria, and Microcystis.
• No anatoxin-a found in aqueous samples.
• However, anatoxin-a found at toxic levels in stomachs of fish.
• Non-detectable amounts of fast-degrading toxins in aqueous samples can be dangerously misleading.
Potentially Toxic CyanobacteriaFound in Salt River Reservoirs
• Aphanizomenon flos-aquae• Anabaenopsis circularis• Anabaena laxa• Anabaena schremetievi• Anabaena torulosa• Anabaena variabilis• Cylindrospermopsis raciborskii• Merismopedia elegans• Microcystis• Pseudanabaena• Oscillatoria aghardii• Oscillatoria limnetica• and several more
• It is impossible to determine toxicity based upon presence of an algal species alone.
• The only way to quantify algal toxins is through direct measurement of either aqueous or biological samples.
• Most of the cyanobacteria found within the reservoirs are ubiquitous and probably do not produce toxins the majority of the time.
• Based upon our large database of algae identifications, there is NO correlation between numbers of potentially toxic species and toxic events.
Why Were the Toxic Events Worse in the Upper Reaches of Saguaro?
• Unknown but pump-back storage at Canyon may play a role.
• This area has had other toxic events and in 2001 we found over 140 µg/L of anatoxin-a.
• This was the highest level of anatoxin-a ever recorded by the reporting lab.
Toxicity based upon Environmental Conditions
• No correlation to toxicity and number of species suggests that a few of the suspect species produce copious amounts of toxin at a specific time based upon environmental conditions.
Allelopathy
Defense from Grazing by Zooplankton
Why were no Humans Affected?
• Fish and mollusks are especially susceptible due to rapid uptake across gills.
• Just because toxicity occurs in fish does not mean toxicity will occur in humans.
• However, fish and zooplankton serve as important biological indicators of toxicity.
Algal Toxin Summary
• Fish kills probably caused by anatoxin-a.• Possibly exacerbated by lysing of cells
due to pump-back storage. • Several potentially toxic species found in
ALL reservoirs surrounding the Valley and no correlation between biomass and toxicity.
• Toxicity probably due to environmental factors such as removal of nutrient limitation, allelopathy, defense from grazing, etc.
• C. raciborksii probably played no role in toxic events.
• Dr. Paul Zimba (USDA) growing 2 isolates of C. raciborskii to check for toxicity.
• Unialgal cultures of all potentially toxic species need to be established and then systematically checked for toxin production under different environmental conditions.
• Without this data, predicting future toxic events by looking for any individual species is meaningless.
Special Thanks• Susan Fitch, Linda Taunt, Jenny
Hickman, Sam Rector, and Amanda Fawley from ADEQ.
• Marc Dahlberg, Kevin Bright, and Larry Riley from AzG&F.
• Dr. Greg Boyer from SUNY
Questions?