Algal Toxin Production in Arid-Land Reservoirs

David Walker University of Arizona

NSF/UA Water Quality Center

http://walter.arizona.edu/

Drought and Wildfire

Rodeo-Chedeski Fire

• The largest wildfire in Arizona recorded history began on June 18th, 2002.

• Burned almost 500,000 acres in the White Mountains to the north and east of Phoenix.

• Several major drainages to the Salt River were within the burn area.

Pre- and Post-fire Nutrient LoadingTota

l N (

mg/L

)

0

5

10

15

20

25

30

35

1998-2001 2002-2004

Year

Missing Rows 15

Rsquare

Adj Rsquare

Root Mean Square Error

Mean of Response

Observations (or Sum Wgts)

0.44874

0.440512

5.617329

5.27942

69

Summary of Fit

Year

Error

C. Total

Source

1

67

68

DF

1720.9701

2114.1441

3835.1142

Sum of Squares

1720.97

31.55

Mean Square

54.5398

F Ratio

<.0001

Prob > F

Analysis of Variance

1998-2001

2002-2004

Level

34

35

Number

0.2124

10.2017

Mean

0.96336

0.94950

Std Error

-1.711

8.307

Lower 95%

2.135

12.097

Upper 95%

Std Error uses a pooled estimate of error variance

Means for Oneway Anova

Oneway Anova

Oneway Analysis of Total N (mg/L) By Year

Tota

l P (

mg/L

)

0

5

10

15

20

25

30

35

1998-2001 2002-2004

Year

Missing Rows 15

Rsquare

Adj Rsquare

Root Mean Square Error

Mean of Response

Observations (or Sum Wgts)

0.688917

0.684274

5.838316

8.924348

69

Summary of Fit

Year

Error

C. Total

Source

1

67

68

DF

5057.5511

2283.7576

7341.3087

Sum of Squares

5057.55

34.09

Mean Square

148.3765

F Ratio

<.0001

Prob > F

Analysis of Variance

1998-2001

2002-2004

Level

34

35

Number

0.2379

17.3626

Mean

1.0013

0.9869

Std Error

-1.76

15.39

Lower 95%

2.236

19.332

Upper 95%

Std Error uses a pooled estimate of error variance

Means for Oneway Anova

Oneway Anova

Oneway Analysis of Total P (mg/L) By Year

Increasing Hypolimnetic Anoxia in Roosevelt

DO

_mg_

per_

L

0

0.1

0.2

0.3

0.4

0.5

0.6

Summer 02 Summer 03 Summer 04

Sampling_Period

All Pairs

Tukey-Kramer

0.05

Rsquare

Adj Rsquare

Root Mean Square Error

Mean of Response

Observations (or Sum Wgts)

0.767716

0.758782

0.056288

0.189455

55

Summary of Fit

Sampling_Period

Error

C. Total

Source

2

52

54

DF

0.54452819

0.16475544

0.70928364

Sum of Squares

0.272264

0.003168

Mean Square

85.9318

F Ratio

<.0001

Prob > F

Analysis of Variance

Summer 02

Summer 03

Summer 04

Level

13

27

15

Number

0.356923

0.167407

0.084000

Mean

0.01561

0.01083

0.01453

Std Error

0.32560

0.14567

0.05484

Lower 95%

0.38825

0.18914

0.11316

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

Primary Production in Roosevelt

Primary Production in Apache, Canyon, and Saguaro

Components:

Chl_a_mgPerm3

DOC_ppm

TOC_ppm

Ammonia_N_mgPerL_asN

NitrateNitrite_N_ppm

Total_P_ppm

Total_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

History of Algal Toxins in Salt River Reservoirs

• August 2000 – Large die-off of Corbicula fluminea in the riverine zone of Saguaro reservoir.

• Found over 140 μg/L of anatoxin-a in aqueous samples.

Cylindrospermopsis raciborskii

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.

• 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.

• Subsequent fish kills, usually beginning in riverine sections, in winter/spring of 2004, 2005, 2006, and decreasing in 2007.

• No early indicators of fish kill activity this year.

• Salinity decreased in reservoirs due to adequate winter precipitation and snowmelt.

Prymnesium parvum

http://www.nies.go.jp/biology/mcc/images/100images/nies-1397.jpg

From Sasaki et al. 2006.

• Causes mass hemolysis of red blood cells.

• Structurally similar to brevotoxin.

• Mass in excess of 1400 AMUs.

• Structure would appear to make cell entry difficult.

•

• .

• Fish toxicosis difficult to explain.

• No studies showing any significant correlation between concentrations of prymnesin in the water to fish toxicosis.

• Likely a toxic fraction.

Fractionation and Quantification of Prymnesin Toxins

• JoAnn Burkholder (NCSU), Paul Zimba (USDA-ARS)– Grow unialgal cultures in bulk– Concentrate cell biomass and dissolved

organics.– Send cell pellets and SPE material for toxin

extraction/assessment.

• Peter Moeller (NOAA)– Biochemical fractionation, toxin class

identification, development of toxin bioassay(s).

– Identification of toxin/development of method for toxin assessment

Potential Factors for Algal Toxin Production in Reservoirs

• Changing nutrient ratios due to watershed disturbance.

Drought/Climate Change

Summary

• Different types of toxins can be produced by reservoirs due to changing environmental conditions.

• Toxin production and presence of species capable of producing toxins are poorly correlated.

• Toxin production of any given species also depends on as-of-yet ill-defined environmental triggers.

• In connected systems, differing nutrient ratios between upstream-downstream reservoirs may trigger toxin production.

• Massive watershed disturbance can result in favoring certain toxin-producing species over others.

Questions?