Harmful Algal Blooms: Forecasting, Monitoring and Managing the Next

ThreatAnne Wilkinson PhD

Joe Bischoff

Colorado Lake and Reservoir Management Association, November 7, 2019

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Outline

• What are HABs?

• When are they a problem?

• How do we monitor them?

• How can we manage them?

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What are Harmful Algal Blooms?

Madison Lake, MN July 2016

200

µmAccumulations of toxic

freshwater microscopic

photosynthetic microorganisms-

Cyanobacteria!

Also known as Blue Green

Algae

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What are Cyanobacteria?

• Individual cells form colonies

• Cyanobacteria can regulation their buoyancy

• Cyanobacteria utilize phycocyanin as a supplementary photosynthetic pigment

• Thrive in warm temperatures as compared to other phytoplankton

50µm

50 µm

Microcystis

Dolichospermum

(Anabaena)

200

μm

Aphanizomenon

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Why are they important?

• There are many different types of cyanotoxins which can co-occur in freshwater systems

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Neurotoxin

(nervous system)

Hepatotoxin

(liver)

Dermatoxin

(skin)

Saxitoxin

Anatoxin

BMAA

Microcystin

Cylindrospermopsin

Lyngbyatoxin

Lipopolysaccharides

200 µm

Cyanotoxins Exposure

• Drinking water

-Microcystin is regulated in drinking water by the EPA and World Health Organization

• Recreational water

-Public and ecological health risk

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Impacts on Drinking Water

• Produce toxins

• Produce Taste and Odor

• Increase chlorine demand and TOC -> increases in disinfection by products

• Increase coagulant usage

• Clog intake screens

• Increases backwash requirements

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Taste & Odor and HABs

• Primary sources are algae and bacteria- some fungi and zooplankton can produce T&O

Common compounds from Cyanobacteria

-Geosmin – earthy and musty

-MIB (2-methylisoborneol) – muddy earthy and musty

-Others include: 2t,4c,7c-decatrienal, 2t,6c-nonadienal, linoienic acid, Beta-cyclocitral and isovaleric acid

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Geosmin and MIB• Produced by cyanobacteria, actinomycetes and other

bacteria

• Cyanobacteria produce it as secondary metabolite and released from cell during death

Look for Planktothrix, Oscillatoria, Dolichospermum, Aphanizomenon, Lyngbya

10Dolichospermum Aphanizomenon Lyngbya

When are they dangerous?• Blooms can be made up of different

types of cyanobacteria

• Some cyanobacteria can produce toxins while others cannot

• Different types of cyanobacteria produce different types of toxins

• Cyanobacteria that are capable of producing toxins don’t produce them all of the time

• Cyanobacteria can produce toxins when they are not in a bloom

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How long are they dangerous?

• Microcystin, can persist weeks-months

• Toxins degrade in UV

• Can be mixed and diluted into the water column

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Non-toxic harmful effects of HABs• Overnight fish kills

• Out-shading over benthic fauna and phytoplankton

• Taste and Odor problems

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Possible causes of HABs

• Excess macro-nutrients

• N, P, Fe

• Multiresource colimitation

• Warm temperatures

• Stable Stratification

Anthropogenic Influences

Industrialized Farming

Climate Change

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Cyanobacteria blooms and their risk factors are increasing

across the globe!

Risk Factors

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Lake Watershed Phosphorus

Loading

Sediment Redox Reactions

Sediment Phosphorus Dynamics

Sondergaard et al. 2001

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What is Causing Phosphorus Release?

�Historic equilibrium phosphorus concentrations represent a balance between burial and release

�Elevated phosphorus in sediment will diffuse into surface waters

� This cycle will continue until the sediment phosphorus peak is reduced

-16

-14

-12

-10

-8

-6

-4

-2

0

0 1 2 3Sedim

ent

depth

(cm

)

Redox- -1

-

Burial of phosphorus

Release of

Phosphorus

Sediment Core Collection

Anoxic P Release

Upper Lunsten

Anoxic P Release Rate

0

0.1

0.2

0.3

0.4

0.5

0 1 2 3 4 5 6 7 8

Days

Ph

os

ph

oru

s (

mg

)

Lower Lunsten

Anoxic P Release Rate

0

0.1

0.2

0 5 10 15 20

Days

Ph

os

ph

oru

s (

mg

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Recommendations for HAB Management in Lakes and Reservoirs

1. Monitoring

2. Management

3. Outreach

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Monitoring Approaches

• System Characterization and Risk Assessment• Physical features that may drive HABs

• Quiescent areas, stratification, high temperatures, nutrient hot spots

• Temperature/DO profiles, nutrients, phycocyanin• Synoptic surveys, routine grab sampling, modeling

• Early Detection and Response• Detect when conditions are high risk for HABs• Detect early, low concentration HAB blooms• Often requires real time monitoring and spatial network• Statistical and modeling tools still in development• Rudimentary understanding of risk factors

• HAB Severity and Longevity• Measure severity of bloom including toxin production• Measure persistence of bllom and toxins

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HAB Characterization

and Risk Assessment

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Spring

Early Summer

Summer

Late Summer

Winter

Accounting for Vertical Heterogeneity in Monitoring• Importance consistent

monitoring because of transient nature of HABs and transport potential

• There can be blind spots in HAB monitoring because of vertical heterogeneity

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Accounting for Horizontal Heterogeneity of HAB

• Accumulate down wind and sheltered areas but can originate in the pelagic zone

• Understand possible hot spots in the lake/reservoir

• Could provide early warnings for possible blooms downwind-

• Target monitoring or management

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HAB Severity and

Longevity

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Monitoring Tools

• In-situ Phycocyanin probe for bulk cyanobacteria

• Phytoplankton composition – in situ or routine grab samples

• Cyanotoxins along drinking water intake, public use areas or areas of frequent HABs

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Monitoring for HABs

1. Sampling options• Remote sensing

• Fixed Depth- in-situ or grab samples

• Depth integrated

2. Cyanobacteria biomass• Phytoplankton Identification-flow

cytometer

• Phycocyanin fluorometry

3.Cyanotoxin Measurements• Microcystin, anatoxin, BMAA…

• Total toxins

• ELISAs, Test Strips, LC/MS/MS

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Quick Tests or Checks

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MPCA CO EPA

Keep in mind –Safety First

- Don’t not intentional contact

water if you think it might be

an HAB without gloves

1. Place a sturdy stick in green floating mat

2. Slowly lift the stick from the water

3. Investigate the end of the stick

-if the stick pulls green strands or threads

it is a benign green algae

-if the stick appears to be covered in paint

it is likely an HAB

Quick Tests or Checks

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1. Safely collect a

water sample (wearing

gloves is encouraged)

2. Place sample in the

refrigerator

3. Leave undisturbed

overnight

4. Inspect the jars

Not an HAB

- the particulates have

settled to the bottom

HAB present

- the particulates have

floated to the top

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Early Detection and

Response

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Statistical Model for HABs

• Early warning indicators can be determined by multivariate analysis from consistent in-situ monitoring data

• Powerful statistical models be used to detangle multi-resource interactions triggering HABs

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Monitoring Summary

• Evaluate and Describe Your System• Know potential hot spots (downwind, stratification) • Sensitive areas (beaches, water intakes) • Identify factors that may lead to HAB

• Watershed loading• Sediment nutrient loading• Quiescent bays or arms• Mixing, prevailing winds, spatial heterogeniety

• Tailor Methods to Risks and Conditions• Known toxin events require more robust monitoring• Intakes, beaches, high risk area

• Develop analytical framework • Risk assessment and early warning/detection in real time• Characterization

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Recommendations for HAB Management

• Watershed Nutrient Management-P, N

• Avoidance Strategies-

Drinking Intake

• In-reservoir Management

• Chemical controls

• Physical controls

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HAB at boat launch. From WI DHS

Watershed Management

• Control external sources of N and P

• Soil conservation practices

• Riparian buffers

• Stormwater BMPs

• Septic and WWTF upgrades

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Avoidance Strategies

• Selective in-take depth

• Source Blending-dilute HABs

• Bypassing- use alternative source

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Chemical Treatments

• P inactivation of sediments- use of coagulants to prevent internal loading from reservoir sediments

• Algaecides- kills algae present in the water column

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Physical Management

• Ultrasonic Treatment-disrupts cell function, local effects

• Mechanical Mixing-removes cyanobacteria from the sun light, CO2 and does not allow for large accumulations of toxins

• Hypolimnetic oxygenation-remove anoxic conditions leading to compounds released from sediment

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Management Cost Applicability Pros Cons

Watershed

Management

High High external sources Reduce external

sources

Requires buy-in from

stakeholders,

Avoidance

Strategies

Moderate

/High

Drinking water

reservoirs, not for

recreation

Avoid intake of

HABs

Need multiple sources, high

frequency monitoring and

infrastructure, effective for

deep sources

Sediment

Inactivation

Moderate

/Low

Internal loading

potential

P reductions for

>10 years, can be

applied in shallow

and stratified lakes

P is not the only driver for

HABs

Hypolimnetic

Oxygenation

High Deep reservoirs, anoxic

conditions must be

present

Manage seasonal

blooms and other

reservoir WQ issues

including sediment

release

Not as effective for shallow

systems, no effect on HAB in

epilimnion

Mechanical

Mixing from

Moderate Deep systems with

anoxia or control of

highly buoyant blooms

Can help with HABs

and other reservoir

WQ issues

Must be well planned to be

effective for HAB control

Ultrasonic

control

Low Broad spectrum control

for local control

Inactivates cells but

does not lyse the

cells

Local effects only

Algaecide Low Bloom is already

present

Quick fix, broad

spectrum, simple to

apply

All toxins will be released,

Implemented when bloom is

just starting to emerge43

Recommendations for Outreach

• Post notices in areas with frequent HABs and popular recreational areas

• Educate residents on HAB health effects

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HAB Strategies Summary

• HAB early warning, detection, and characterization is challenging• Rapidly advancing science regarding HABs

• Early detection models and frameworks

• Risk factors and HAB drivers

• 3-Dimensional spatial heterogeneity

• System characterization is critical• Develop an understanding of conditions and locations that may favor

HABs• Downwind areas, sheltered areas, nutrient hot spots

• Monitor physical conditions that favor HABs

• Tailor monitoring intensity to risk

• Management strategies are limited by driver assessment• Many tools address symptoms after bloom starts• P reduction may not be enough – multi-resource limitation• Early detection assessments are in early stages of development and

only give a few days warning

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Thank you!

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