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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0 5 10 15 20 25 30 35Y

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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.0 .1 .2 .3 .4 .5 .6 .7 .8 .9 1.0 1.1Y

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?