Download Harmful Algal Blooms Issue Brief

Issue Brief
Harmful Algal Blooms
Introduction
Healthy fresh and saltwater environments naturally contain some algae, but excess algae growth can
negatively impact water, food, and air quality. Red tides, one type of harmful algal bloom (HAB),
diminish the health of our environment, negatively impact public health, and have dramatic economic
consequences for fisheries, recreation, and tourism. Reports of adverse health impacts from HABs are
increasing, and the higher water temperatures and extreme weather events associated with climate
change make HABs even more likely to occur in the future. This brief explores why HABs are a problem
and what strategies are available to address them.1
Background
Algae form the foundation of aquatic ecosystems and act as a natural indicator of aquatic health. But
when these environments experience an excess in nutrient levels, an overabundance of algae, or
“bloom,” occurs. If those algae are one of a small percentage of toxin-producing species, the bloom is
referred to as harmful. HABs in saltwater affect all coastal states.2 In freshwater, factors like warm
temperatures, light, and increased phosphorus and nitrogen levels from agricultural runoff may increase
the possibility of a bloom. HABs can quickly cover water surfaces, deplete water of oxygen levels, and
block sunlight. Blue-green algae (also known as “cyanobacteria”) are common causes of HABs that
impact food and drinking water supplies and disrupt ecosystem functions.
Economic Consequences
HABs have extensive, adverse impacts
on the United States economy. A 2006
study estimated that HABs cost the
United States an average of $82 million
per year, 3 with the highest annual costs
associated with medical expenses
associated with HAB exposure and from
HABs’ impact on commercial fisheries.4
This is an increase of $40 million in
estimated impacts from 1987, 5 and
likely underestimate current HAB
economic impacts. These estimates do
not include the indirect costs associated
with loss of consumer confidence in
seafood products, loss of tourism
revenue, or impacts of HABs on the
Pacific Northwest considered. 6
The Cost of HABs4, 6
•Impact on commercial fisheries due to New
England red tide in Maine and Massachusetts in
2005.
$23
Million
•Annual impact of red tide in Florida
$19-32
Million
•Impact of commercial oyster fishery closures,
lost tourism, and beach cleanup due to red tide
in Galveston, Texas in 2000
$10
Million
•Annual impact of real estate value and hotel
business losses and increased clean-up costs due
to macroalgae in Maui, Hawaii.
$20
Million
•Impact on commercial, subsistence, and
recreational fisheries in the Pacific Northwest in
2002/2003.
$10-12
Million
Health Impacts
HABs have been shown to negatively impact health by contaminating food supplies, drinking water
supplies, and recreational waters.6 In most events, HAB exposure may cause nausea, rashes, or other
minor effects, but in some cases, exposure can cause serious injury or death. Consuming shellfish
contaminated with brevetoxins (the toxins associated with Florida’s red tides), may cause neurotoxic
© Association of State and Territorial Health Officials 2015
202-371-9090
2231 Crystal Drive, Ste 450, Arlington, VA
www.astho.org
Issue Brief
shellfish poisoning (NSP).7 Ciguatoxins, also capable of accumulating through food webs, are found in
larger fish such as barracuda and snapper, and cause similar neurological and gastrointestinal symptoms
to NSP if consumed.8 Increasing anecdotal evidence also suggests that breathing air near HABs or
swimming in polluted water may cause or exacerbate respiratory and skin irritations. HABs in freshwater
systems have been responsible for many reported illnesses across the United States along with Toledo,
Ohio’s recent drinking water supply shutdown.9, 10 In Washington state, freshwater HABs have been
observed in more than 132 lakes, resulting in animal and human illnesses and animal deaths in some
lakes.11
Policy
EPA is currently developing a comprehensive set of guidelines for managing HABs. In May 2015, EPA
released health advisories for cyanobacteria toxins that pertain to drinking water exposures to
microcystin and cylindrospermopsin for periods of up to 10 days. The table below shows that the health
advisory values are lower for young children than for adults:
Drinking Water Toxin Health Advisory Levels (Based on 10 Day Exposure)
Toxin
School-Aged Children and Adults
Microcystin
Bottle-Fed Infants and
Preschool Children
0.3 ug/L
Cylindrospermopsin
0.7 ug/L
3 ug/L
1.6 ug/L
Twenty states have guidelines or standards for drinking water or recreational waters, and the World
Health Organization published a guideline for one type of cyanobacteria toxin, microcystin-LR toxin, in
1988.12 Developing guidelines for the dozens of types of microcystins that may be present in a bloom is
hampered by the lack of adequate toxicity data for microcystins other than for microcystin-LR.13,14
Climate Change
Scientists predict that climate change will impact the frequency and duration of HAB events by changing
the conditions of freshwater and marine environments. Projections are summarized in the table below:
Climate Trend
Warming
temperatures
Impact on HAB


Warmer temperatures:
o Favor the growth of certain species of algae, some of which grow
faster at temperatures over 77 degrees Fahrenheit.15
o Impair the ability of wind to mix water, as well as the oxygen and
nutrients it contains, resulting in faster algae growth.
o Decrease the viscosity, or thickness, of water, increasing the speed at
which certain species of algae can float to the surface, where they
directly utilize atmospheric carbon dioxide (CO2) to grow at faster
rates.
HABs warm water temperatures, creating a positive feedback cycle and an
environment that is conducive to long-term growth.
© Association of State and Territorial Health Officials 2015
202-371-9090
2231 Crystal Drive, Ste 450, Arlington, VA
www.astho.org
Issue Brief
Climate Trend
Increased
precipitation
Increased
drought
Increased carbon
dioxide (CO2)
concentrations
Sea level rise
Impact on HAB
 Climate change is projected to increase extreme weather events, such as
storms and heavy rainfall.
 Surges in runoff transports nutrients into water, elevating phosphorus and
nitrogen levels. In urbanized areas, fertilized lawns contribute to elevated
nutrient levels in water bodies.
 Climate change is projected to increased dry periods, which lowers water
levels and increases salt concentration.
 Increased saline conditions favor marine algae invasion into freshwater
systems and stimulate the release of toxins.
 Because algae undergo photosynthesis, they grow faster in conditions with
elevated dissolved CO2.
 Human activities contribute to an increase in atmospheric and dissolved CO2,
which increases algae growth rates.16
 As algae float to the surface, they can utilize dissolved and atmospheric CO2.
 Under elevated CO2 levels, water acidity impacts zooplankton’s grazing
activity, which typically acts to naturally control HABs.
Sea level rise increases the magnitude of existing continental shelves, which
provide stable coastal environments that promote the growth of algae.
Monitoring and Management
The growing challenge of HABs highlights the need to conduct further research and advance monitoring
capabilities, which are critical to limiting health impacts by detecting toxins early. The National Oceanic
and Atmospheric Administration (NOAA) is authorized and mandated by the Harmful Algal Bloom and
Hypoxia Research and Control Amendments Act to advance such efforts. With funding secured from
2014-2018, progress is being made towards enhancing a national program to prevent HAB and hypoxia
events. 17 A 2007 report by the Interagency Working Group on Harmful Algal Blooms, Hypoxia, and
Human Health of the Joint Subcommittee on Ocean Science and Technology outlines the HAB prediction
and response efforts available to state resource managers:
1. Monitoring: Monitoring is a critical first step, because prediction and response is not possible
without quantitative data. Multiple methods are needed to characterize and identify each HAB
species and its toxins, as no single method can fulfill all purposes. Coordinating monitoring
activities may help predict which set of conditions are conducive to HABs. CDC’s National
Outbreak Reporting System, launched in 2009, supports voluntary outbreak reporting across the
states and territories.
2. Prediction: Prediction and tracking methods that integrate satellite data and transport models
with monitoring data are now operational for Karenia brevis off the Florida coast, and NOAA also
manages the HAB Operational Forecast System. Accuracy is improved when monitoring is tailored
to best address issues of concern in a particular location.18
3. Control: A number of new approaches for controlling HAB have been identified for some species,
including physical cell removal by clay flocculation, using natural by-products of aged barley straw
as algaecides, or using natural HAB-specific pathogens such as bacteria, viruses, and parasites19.
© Association of State and Territorial Health Officials 2015
202-371-9090
2231 Crystal Drive, Ste 450, Arlington, VA
www.astho.org
Issue Brief
4. Event Response: Several HAB event response programs have been established to minimize the
impacts of events, mobilize resources, and provide data to understand and predict future events.
5. Coordination: The wide range of available scientific tools and information has made it easier for
states to coordinate research, monitoring, and response efforts across researchers, public health
and resource managers, and federal agencies at both the local and national level.
An Integrated Approach to Management
Evidence strongly suggests that climate change will likely influence the frequency and severity of HAB
events. Despite the dearth of comprehensive programs to address HABs, states can still leverage
preventive strategies that both reduce the likelihood of HABs and mitigate climate change impacts.
EPA’s Healthy Watershed Program is one strategy that contributes to both of these outcomes. A healthy
watershed helps mitigate flooding during high rainfall events by providing good storm water infiltration
and groundwater storage. A well-functioning riparian zone also regulates air and water temperatures,
increasing water quality and preventing future HAB events, resulting in reduced spending for costly
water treatment infrastructure.
Across the United States, more than 700 cities are still using wastewater systems that combine storm
water with residential and commercial sewage. During high rainfall events, these systems become
overwhelmed, allowing industrial waste, toxic material, and nutrient-rich untreated human waste to
bypass treatment plants and overflow into waterways, triggering HAB events. By upgrading these
systems to more modern facilities, states can address the upstream factors associated with nutrient
runoff as well as manage flooding. Through the National Enforcement Initiative, EPA is beginning to take
action against municipal sewer systems that violate the Clean Water Act by unlawfully discharging raw
sewage into waterways. Several of these municipalities have since agreed to make significant upgrades
to their sewer systems to resolve their violations, which will effectively reduce the likelihood of HAB
events in their waterways.20
Conclusion
Maintaining healthy marine and freshwater resources is critical to ensuring the proper functioning of
ecosystems and the economic and social benefits that they provide. Algal blooms present a serious
threat to ecosystem health and the sustainability of natural resources, regardless of whether a bloom
event is toxic to humans. Over the past several decades, scientists have observed an increase in the
frequency and duration of blooms, which has led them to more closely examine the impacts of climate
change, which are projected to exacerbate HAB impacts. The ability to address HABs impacts effectively
is hampered by a lack of understanding of how to forecast, monitor, and assess toxin levels associated
with HAB events. Continued federal support for research and policy development can provide health
departments, researchers, and public health practitioners with the tools they need to develop better
guidance and recommendations and increase the HAB management options available to
decisionmakers. Complementary management strategies that reduce the incidence of HAB events and
mitigate the impacts of climate change are also showing promise while states continue to discuss
regulations and policies.
This resource was developed thanks to support from CDC Cooperative Agreement 5U38HM000454. Its
contents are solely the responsibility of the authors and do not necessarily represent the official views of
CDC.
© Association of State and Territorial Health Officials 2015
202-371-9090
2231 Crystal Drive, Ste 450, Arlington, VA
www.astho.org
Issue Brief
1
Woods Hole Oceanographic Institute. “Distribution of HABs in the US.” Available at
http://www.whoi.edu/science/B/redtide/HABdistribution/HABmap.html. Accessed 2-10-2015.
2
CDC. “Harmful Algal Blooms (HABs).” Available at http://www.cdc.gov/nceh/hsb/hab/. Accessed 11-13-2014.
3 National Oceanic and Atmospheric Administration. “Harmful Algal Blooms.” Available at http://oceanservice.noaa.gov/hazards/hab/. Accessed
11-13-2014.
4
National Centers for Coastal Ocean Science. “Economic Impacts of Harmful Algal Blooms (HABS).” Available at
http://www.cop.noaa.gov/stressors/extremeevents/hab/current/hab_econ.aspx. Accessed 2-9-2015.
5 Anderson DM, Hoagland P, Kaoru Y, White AW. Estimated Annual Economic Impacts from Harmful Algal Blooms (HABs) in the United States.
Woods Hole, MA; 2000:96. Available at: http://www.whoi.edu/fileserver.do?id=24159&pt=10&p=19132. Accessed 11-13-2014.
6
Ibid.
7 Ibid.
8 Ibid.
9 Hilborn, E., et al. (2014, January). Algal Bloom Associated Disease Outbreaks Among Users fo Freshwater Lakes. Morbidity and Mortality
Weekly Report, 63(01), 11-15.
10 Egan D. Toxic algal bloom shuts off water, but green slime limited so far to Toledo. Available at
http://www.cleveland.com/outdoors/index.ssf/2014/08/toxic_algal_bloom_shuts_off_wa.html. Accessed 3-24-2015.
11
Trainer, V.L., and F.J. Hardy. 2015. Integrative Monitoring of Marine and Freshwater Harmful Algae in Washington State for Public Health
Protection. Toxins, 7: 1206-1234.
12 EPA. “Nutrient Pollution Policy and Data.” Available at http://www2.epa.gov/nutrient-policy-data. Accessed 2-9-2015.
13 Minnesota Department of Health. “Microcystin-LR in Drinking Water”. Available at
http://www.health.state.mn.us/divs/eh/risk/guidance/gw/mclrinfo.pdf. Accessed 2-9-2015.
14
EPA. “Microcystins.” Available at http://iaspub.epa.gov/tdb/pages/contaminant/contaminantOverview.do?contaminantId=-1336577584.
Accessed 2-9-2015.
15 Center for Earth and Environmental Science. “What Causes Algal Bloom?” Available at http://www.cees.iupui.edu/research/algaltoxicology/bloomfactors. Accessed 11-13-2014.
16
Netherlands Organization for Scientific Research. “Rising CO2 levels will intensify algal blooms across the globe.” Available at
http://www.nwo.nl/en/news-and-events/news/2014/alw/rising-co2-levels-will-intensify-algal-blooms-across-the-globe.html. Accessed 11-132014.
17 Jewett, E.B., Lopez, C.B., Dortch, Q., Etheridge, S.M. 2007. National Assessment of Efforts to Predict and Respond to Harmful Algal Blooms in
U.S. Waters. Interim Report. Washington, DC; 2007: iii. Available at
http://www.cop.noaa.gov/stressors/extremeevents/hab/habhrca/Predict_Resp_IntRpt_0107.pdf. Accessed 11-13-2014.
18 NOAA. “NOAA HAB-OFS Newsletter.” Available at http://tidesandcurrents.noaa.gov/hab/newsletters/HAB-OFS_Newsletter_201406_08.pdf.
Accessed 2-9-2015.
19 National Sea Grant College Program. Prevention, Control and Mitigation of Harmful Algal Blooms A Research Plan. Silver Spring, MD; 2001:
13. Available at: http://www.whoi.edu/science/B/redtide/pertinentinfo/PCM_HAB_Research_Plan.pdf. Accessed 11-13-2014.
20
EPA. “National Enforcement Initiative: Keeping Raw Sewage and Contaminated Stormwater Out of Our Nation's Waters.” Available at
http://www2.epa.gov/enforcement/national-enforcement-initiative-keeping-raw-sewage-and-contaminated-stormwater-out-our. Accessed 29-2015.
© Association of State and Territorial Health Officials 2015
202-371-9090
2231 Crystal Drive, Ste 450, Arlington, VA
www.astho.org