harmful algal blooms: forecasting, monitoring and managing ...harmful algal blooms: forecasting,...
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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
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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
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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!
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Risk Factors
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Lake Watershed Phosphorus
Loading
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Sediment Redox Reactions
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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
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Sediment Core Collection
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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
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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
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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
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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
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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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