Blue-green Algal Toxins in Minnesota Lakes

Harmful Algal Bloom Workshops 2008

Steve Heiskary & Matt Lindon

Outline Outline Brief history on MN algal toxin issues; Brief history on MN algal toxin issues; Overview 3 studies that examine blueOverview 3 studies that examine blue--green algal toxins in MN green algal toxins in MN –– focus on focus on microcystin (MC); microcystin (MC); Overview of findings Overview of findings Recommendations based on studies to Recommendations based on studies to date;date;

Minnesota History With Algal Toxins Minnesota History With Algal Toxins Accounts of algal toxicity in MN go back to 1800’s on live stock Increasing concern and reports world wide Three dog deaths in 2004 (Fish and Benton) prompted further work on this issue. 2005 MPCA joined MDNR, MDH and the Minnesota Veterinary Medicine Association (MVMA) to form the Minnesota Blue-green Algal Toxicity Workgroup 2006 study conducted to examine MC in several eutrophic lakes in two south central MN counties 2007

Five confirmed dog deaths Very high MC results (>80,000 µg/l)National Lake Assessment assessed MC in 50 randomly-selected lakes; MC monitored in 35 southern MN lakes;

Questions addressed in the 2006 studyQuestions addressed in the 2006 study

What is the range in MC in eutrophic / What is the range in MC in eutrophic / hypereutrophic MN Lakeshypereutrophic MN LakesIs there a significant difference in nearIs there a significant difference in near--shore shore MC as compared to midMC as compared to mid--lake?lake?Is there seasonality to MC concentrationIs there seasonality to MC concentrationss??What limnological and physical factors appear What limnological and physical factors appear to be associated with high MC?to be associated with high MC?How can these findings be used to How can these findings be used to communicate risk to lake users?communicate risk to lake users?

2006 South2006 South--Central MN StudyCentral MN Study

•12 eutrophic –hyperutrophic lakes

•Sampled six times May- Sept.;

•Mid-lake “pelagic” site – full water chemistry

•Near-shore (bloom hunting) site, typically downwind or distinctly higher algal concentration;

Methods Methods Surface grab samples were taken monthly MC samples underwent triple freezing, cell lysis procedure. MC analysis was done at MDH

ELISA (Enzyme-Linked ImmunoSorbent assay) Method detection limit (MDL) 0.15 µg/L. The analysis tests for total MC

No MN standardsNo MN standardsWorld Health Organization (WHO) Risk Categories World Health Organization (WHO) Risk Categories ((used as reference in our studyused as reference in our study))

<1 <1 µµg/L (ppb) very low (below drinking water guideline), g/L (ppb) very low (below drinking water guideline), 11--10 10 µµg/L Low, g/L Low, 1010--20 20 µµg/L Moderate, g/L Moderate, 2020--2000 2000 µµg/L High g/L High >2000 >2000 µµg/L Very highg/L Very high

Guidelines for safe recreational water environments (WHO, 2003).

Standards or guidelines

71 Pelagic samples56 nearshore samples142 Total samples

8 ND's

MC Distribution by Site and Risk Category

11

33

5

8

2

25

37

6 6

0

5

10

15

20

25

30

35

40

0.075-1 >1-10 >10-20 20-2000 >2000

Low Risk Low Risk ModerateRisk

High Risk Very HighRisk

MC ppb distribution within WHO risk categories in ppb

Freq

uenc

y

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

Cum

ulat

iveNear shore Sites

Pelagic Sites

Near shore Site Cumulative %

Pelagic Site Cumulative %

Near-shore: Scum vs. no Scum

2

8

32 2

9

24

1

3

0

5

10

15

20

25

30

0.075-1 >1-10 10-20 20-2000 >2000

Low Risk Low Risk Moderate High Risk Very High Risk

MC µg/L Range and WHO risk categories

Freq

uenc

y

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

Cum

ulat

iveBloom site w/ scum

Bloom site w/o scum

Cumulative % w/ scum

Cumulative % w/o scum

Near Shore sites

020406080100

Ballantyne

Cedar

Duck

Eagle

George

Hook

Loon

Madison

Marion

Otter

Silver

Stahl's

MC µg/L

99

2,200

140

8,250

High

R

MayJuneJulyAugust EarlyAugust LateSeptember

Pelagic sites

0 20 40 60 80 100

Ballantyne

Cedar

George

Madison

Marion

Stahl's

MC µg/L

MayJuneJulyAugust EarlyAugust LateSeptember

High Risk

Duck

Eagle

Hook

Loon

Otter

Silver

Primary sites

0 50 100 150 200

Ballantyne

Cedar

Duck

Eagle

George

Hook

Loon

Madison

Marion

Otter

Silver

Stahls

Chl-a ppbSeptember August Late August EarlyJuly June May

Pelagic Sites

Mean 64Median 47.5

Bloom sites

0 50 100 150 200

Ballantyne

Cedar

Duck

Eagle

George

Hook

Loon

Madison

Marion

Otter

Silver

Stahls

Chl-a ppb

September August Late August EarlyJuly June May

Near Shore Sites

Mean 95Median 65.1

Mid summer High Chl-a

But Low MC

0%10%20%30%40%50%60%70%80%90%

100%

10 or less >10-20 >20-30 30-60 >60

Chl-a Range (ppb) or Bloom Intensity

% M

C o

ccur

renc

e

>2000 >20-2000 >10-20 >1-10 .075-1

MC versus bloom intensity. Based on 109 pairs of MC & chl-a data

Percent occurrence of MC risk levels relative to algal bloom intensity

Low Moderate High

Spearman Rank Correlations for MC and Select Variables:

Sig. pos (+): pH, chl-a attributed to MC producers & chl-a/TSV

Sig. neg (-): alkalinity, conductivity, Secchi

-1.0-0.8-0.6-0.4-0.20.00.20.40.60.81.0

Alkalin

itySpe

c Con

d

Secch

i Dep

th% Phe

oORP

Zoo S

ize

Wind In

tensit

y Zo

o Ab

Temp

% Clou

dy ClDO Sat

Pheo

Color

DO TS

S TPSuit

Rec TKN

% BG

Phy C

ond

Chl a

TSV

Chl-a /

MC p pH

R

Conclusions from the 2006 Study Conclusions from the 2006 Study Likelihood of encountering measurable MC at pelagic site?Likelihood of encountering measurable MC at pelagic site?

94% MC results were above mdl at all sites (n=79)94% MC results were above mdl at all sites (n=79)How do they compare to WHO guideline levels?How do they compare to WHO guideline levels?

25% of the results were above the WHO low risk category 25% of the results were above the WHO low risk category Do MC conc. differ between nearDo MC conc. differ between near--shore and pelagic sites?shore and pelagic sites?

Significantly different distributions Significantly different distributions 40 % of mid40 % of mid--lake were less than 1 lake were less than 1 µµg/L vs. 23% of nearg/L vs. 23% of near--shoreshoreGreater occurrence of high risk levels at nearGreater occurrence of high risk levels at near--shore shore The likelihood of a moderate to high risk MC at a nearThe likelihood of a moderate to high risk MC at a near--shore with a scum is 25%shore with a scum is 25%

ContinuedContinued

Is there seasonality to MC levels in these lakes?Is there seasonality to MC levels in these lakes?No distinct seasonal trend evident; No distinct seasonal trend evident;

As bloom intensity increases is there a greater likelihood of As bloom intensity increases is there a greater likelihood of encountering high MC values? encountering high MC values?

Yes, as chlYes, as chl--a exceeded 30 a exceeded 30 µµg/L (severe nuisance bloom levels) g/L (severe nuisance bloom levels) risk of high MC increased to ~ 15%; in contrast at lower bloom risk of high MC increased to ~ 15%; in contrast at lower bloom levels all MC was in the low risk category.levels all MC was in the low risk category.

What limnological factors appear to be associated with high MC?What limnological factors appear to be associated with high MC?+ association with: pH, TSV and chl+ association with: pH, TSV and chl--a of MC producers a of MC producers -- association with: alkalinity, Cond. and Secchi association with: alkalinity, Cond. and Secchi

How can these findings be used to communicate risk to lake usersHow can these findings be used to communicate risk to lake users??Highest risk MC is most often associated with severe nuisance Highest risk MC is most often associated with severe nuisance blooms that result in low transparency (0.5 m or less), high pH blooms that result in low transparency (0.5 m or less), high pH (9.0 or more), and that occur most frequently in downwind near (9.0 or more), and that occur most frequently in downwind near shore areas;shore areas;

Algal Toxin studies: 2007

NLAP study with midNLAP study with mid--lake & nearlake & near--shore MC shore MC measures for 50 lakes;measures for 50 lakes;35 lakes in SW MN included Saxitoxin as 35 lakes in SW MN included Saxitoxin as well as MC;well as MC;Responding to reports of severe blueResponding to reports of severe blue--green green blooms, dog deaths and related concerns blooms, dog deaths and related concerns ––as early as June;as early as June;

NLAP Methods NLAP Methods

Analysis Analysis Cells were lysedCells were lysedAnalyzed with ELISA for total MCAnalyzed with ELISA for total MCMDH Lab for PCAMDH Lab for PCAUSGS Lawrence KS for EPA samplesUSGS Lawrence KS for EPA samples10 of EPA samples will be scanned 10 of EPA samples will be scanned MDL 0.15 MDL 0.15 µµg/L. g/L.

CollectionCollection

index site for EPA & MPCAindex site for EPA & MPCA

random nearrandom near--shore site shore site

NLAP: NLAP: Geographic Geographic

Distribution of Distribution of MCMC

Highest MC concentration: Upper Sakatah 44 ug/L

NLAP MC distributions for midNLAP MC distributions for mid--lake & nearlake & near--shoreshore

0.1 1.0 10.0MC µg/L

0.0

0.1

0.2

0.3

0.4

0.5

0.6

Proportion per B

ar

0

10

20

30

40

50

60

# of

sam

ples

Drinking Water Guidline

NLAP MC Study ConclusionsNLAP MC Study ConclusionsStratified random MC results were lower than previous Stratified random MC results were lower than previous targeted studies (MC max 44 ppb)targeted studies (MC max 44 ppb)Somewhat of a geographic trend in MC distribution Somewhat of a geographic trend in MC distribution Index and Nearshore results were similar (when lakes Index and Nearshore results were similar (when lakes and sites are selected randomly);and sites are selected randomly);

1

10

100

1000

10000

100000

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ton

Cry

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Bal

d Ea

gle

FOU

NTA

IN

PE

LTIE

R

Circ

le

µg/L

2004 200605 2007

Responding to Public ConcernsResponding to Public Concerns

Very High

High

Low

0.1 1.0 10.0 100.0 1000.0 10000.0Log MC µg/L

07 NLAP Index

07 NLAP Near-shore

Index 06 study

Near-shore 06 study

Response

Comparison of MC concentrations from: NLAP study, 2006 south-central MN lakes, & response –based monitoring.

SummarySummary2006 study supplied useful information relative to the range, seasonality and association of MC and other factors in eutrophic MN lakes. http://www.pca.state.mn.us/water/lake.html

2007 stratified-random study exhibited lower MC (relative to other studies); however it demonstrated that MC is present at measurable concentrations in a wide range of lakes in MN; (posted at: http://www.pca.state.mn.us/water/nlap.html )

Incident response sampling often results in high MC levels;

Based on these studies - Current recommendation to avoid contact with blue-green algal blooms is sound; further, blooms that yield very low transparency (< 0.5 m), high pH (>9.0), and distinct surface scums are highly likely to have high MC concentrations.