HomeMy Public PortalAboutAttachment 1. Cyanobacteria Health Agent Guide 2022 by Karen Malkus-Benjamin
Managing cyanobacteria involves many different facets.
There are important questions health agents face, including:
What level of risk do Harmful Cyanobacterial Blooms (HCB) pose to the public in my
Town?
How are different segments of the public exposed to cyanotoxins at different beach sites?
What are the critical details and data I need to effectively make decisions to protect public
health?
Putting together all the factors to address cyanobacterial blooms can be
overwhelming.
The goal of this guide is to help frame the topic, and share helpful strategies to make
day-to-day life of a health agent more effective and manageable.
INTRODUCTION:
PUBLIC HEALTH AND CYANOBACTERIAL BLOOMS
Harmful cyanobacterial blooms (HCB’s) are becoming more common in the USA and on Cape
Cod. The risks are not well understood by the general public, and harm from exposure to toxins
is often avoidable.
Health risks to the public are organized in the charts above.
Health agents may be less concerned with low risk/and unlikely exposure to things like Cercaria (or
Swimmer’s Itch) which is miserable, but not life threatening. Health agents also consider different levels of
risk to different populations, shown-in the lower chart.
The greatest threats to public health at pond beaches are highlighted in red. Dealing with the risks of
cyanobacterial blooms is especially important because of the increasing frequency and the severity of
cyanotoxins.
The State Bathing Beach regulations gives authority and responsibility to local health agents to limit
swimming in waters that: “constitute a menace to health.”
When you consider the acute and chronic risk of cyanotoxins to public health, especially compared to other
beach risks, health agents need to weigh how to best protect their citizens and staff.
The State Law clarifies swimming should not be permitted if there is scum, or lack of clarity.
Moreover, highlighted in section C of 105 CMR, the public should not be exposed to hazardous
materials, which includes cyanotoxins.
WHO (World Health Organization) states “Cyanobacterial toxins are among the most
hazardous substances, widely found in waterbodies.” Health agents can protect public
health by helping beach goers to avoid these hazardous materials. When cyanotoxins are
at levels of concern, keeping the public out of the pond water and away from activities
with pond water spray-keeps the public safer.
Health agents have limited funds and time-so often monitoring ponds is not a choice.
However, when monitoring ponds specifically for cyanobacteria is possible, there are many
advantages both in the short term and long term.
PART 1
Stick test
The first step, when you see a bloom, is to ask yourself “Is it cyanobacteria?”
The always helpful-STICK TEST-can quickly give you important clues.
In this picture is a filamentous green algae that is edible by pond creatures and
not toxin producing… so…no worries!
Don’t assume you understand a bloom with one visit to a pond.
Depending on when you visit a pond-you can get inaccurate information about the status of a bloom.
Scum and Clarity
Concerns
If a bloom reduces visibility to
<4 feet, an automatic closure
posting is recommended at the
swimming beaches.
Poor visibility increases risk of
drowning, in addition to possible
exposure to endotoxins from the
dense cyanobacterial cells.
What is significant scum?
Thin scum lines should not be disregarded. Some of the
highest levels of toxins have been measured in ponds where
scum was not documented at the time of sampling.
Toxins are invisible.
Toxins can be at high levels as the cyanobacteria cells are
degrading and the water is becoming more clear.
The species of cyanobacteria in the
scum is the key information.
Microscope identification gives you
clues about toxicity.
https://www.inaturalist.org/guides/6092
Every pond is unique and there are yearly variations. Monitoring can capture variability and
help forecast blooms using the Cyanoscope and CyanoCasting (EPA, Leland-Haney methods.)
Regular weekly monitoring is most helpful to capture when blooms become toxic.
Links for methods: Cyanoscope https://cyanos.org/cyanoscope-details/#methods
CyanoCasting http://lim-tex.com/wp-content/uploads/2018/05/CyanoCasting_Handbook_v18.pd
PART 2
CYANOBACTERIA MONITORING
Chl-a = __
Phycocyanin = __
H20 Temperature= __
In the graphs above, you can see the different bloom patterns in two Marstons Mills ponds in Barnstable, MA.
The ponds are of similar size, about 50 acres, with different bathymetry-LPMM shallow, Shubael deep.
The CyanoCasting phycocyanin fluorometry data (PC in red) of the Bloom Forming Colonies (BFC)-shows changes in the
cyanobacteria population and periods of rapid growth of the bloom.
LPMM (Long Pond Marstons Mills) had a single bloom in July 2020.
Shubael had a long season of bloom peaks and a secondary fall bloom.
Both ponds were dominated by microcystis (LPMM microscope slide image.)
Both ponds in 2020 produced microcystin toxin above EPA and State recreational standards, which were measured with Abraxis MC
test kits using shore-line (WLW) grab samples.
Any questions about species identification can easily be resolved if microscope images are
shared with the Cyanoscope project on i-Naturalist. Species ID is confirm by multiple experts.
Monitoring regularly helps pond managers anticipate toxic events. Posting with multiple tiers, using the
monitoring data, species ID, and toxin information can achieve protective measures with less scrambling,
especially around peaks in the season like the Fourth of July, when blooms are common and Town offices
are closed.
“The most effective way of protecting public health from a harmful algal
bloom is knowing ahead of time to avoid water containing cyanobacteria.”
EPA toolkit
CYANOBACTERIA BLOOMS ARE INDICATORS OF POND HEALTH
Cyanobacteria monitoring is an effective tool to help understand overall pond health and to prioritize
town actions. Cyanobacterial blooms are indicators of ecosystem imbalances.
Blooms occur in struggling ponds. Yearly toxic events indicate the need for further review of the
human sources that are feeding the toxic cyanobacteria. Towns can focus resources to ponds where
the need is most urgent.
For example: Starting with redirecting and infiltrating storm run-off in the beach areas, and
shorelines of ponds, where we find the most toxic blooms.
Here is the overview a cyanobacteria management flow chart, which we will look at step-by-step:
Step 1= Picking monitoring sites
Step 2= Monitoring and screening for toxic blooms
Step 3= Testing and confirming toxicity
Step 4= Posting beach
PART 3 - PUTTING IT ALL TOGETHER
Pond site triage saves time and addresses critical health situations more effectively.
Monitoring gives a useful perspective, which is unavailable from snap-shot sampling.
Links for methods: Cyanoscope https://cyanos.org/cyanoscope-details/#methods
CyanoCasting http://lim-tex.com/wp-content/uploads/2018/05/CyanoCasting_Handbook_v18.pd
STEP 3 AND 4
Toxin tests to confirm bloom conditions are vital for an effective program.
Using clear decision paths that deal with specific toxins levels and flexible posting options
will help health agents deal with the dynamic risk assessment.
Reopening is complex-often misunderstood-TOXINS ARE INVISIBLE and degrade
at different rates!!!! The water may look clear and fluorometry pigment values low,
but toxins may be at their highest levels.
Here is an example of a safe reopening sequence with microcystin (MC) toxin
Currently, there are no State or EPA regulatory guidelines for anatoxin-a levels.
Anatoxin-a is a potent toxin impacting the nervous system and it is important to consider now
and plan for in the future.
PART 4 - COMMUNICATIONS