Risk Wise

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Development and implementation of a

forecasting and warning system for harmful

algal blooms by the US National Oceanic and

Atmospheric Administration (NOAA)

Nathalie Valette-Silver, Quay Dortch, Richard P. Stumpf, R.Wayne Litaker, Marc E. Suddleson and Gary C. Matlock

National Centers for Coastal Ocean Science, NOAA, USA

he US National Oceanic and Atmospheric Administration

(NOAA) is working with partners to develop forecasting

systems for harmful algal blooms (HABs) to increase the

capacity of local managers to mitigate impacts. HABs impact

human and animal health as well as coastal economies through

the production of toxins or deterioration of water quality. The

completed forecasting system will encompass areas prone to HABs

along the east, west, and Gulf of Mexico coasts of the US as well

as in the Great Lakes. An operational HAB forecast was estab-

lished on the west Florida shelf in 2004. A demonstration is

currently underway in the western Gulf along the Texas coast. A

second operational forecast is functioning in the Pacific Northwest

along the Olympic coast. Progress is also being made in the Gulf

of Maine, other areas of the Pacific Northwest, in California and

the Great Lakes. The forecasting and warning systems use in situ

and remote sensing observations, oceanographic models, and fore-

casts of physical forcing mechanisms to predict and detect blooms,

their movements, and impacts. New technologies are being devel-

oped to further these capabilities, including informing the public

and managers so as to maximize the likelihood for responding to

these potentially disastrous events.

Phytoplankton microscopic plants form the basis of the food webs

that support most aquatic life. While phytoplankton species are gener-

ally harmless, a few species can produce powerful toxins, hypoxia or

a significant degradation in water quality. These effects are most

serious when favourable conditions allow detrimental species to

proliferate, resulting in HABs. HABs are natural phenomena that

appear to have increased in recent years due to environmental changes

and human activities (e.g. increased water temperature, enhanced

nutrient supply, introduction of invasive species).

Many adverse

effects on both humans and living resources are due to toxins released

directly into the air and water, concentrated by shellfish or other

grazers and bio-accumulated in the food chain.

HABs became an issue when it was discovered that they impacted

human health and economic well being. In the marine systems, fish,

birds, marine mammals and humans can all suffer significant illness

or death after being in contact with the toxins (via swimming or

breathing) or after ingesting shellfish, fish or other food items tainted

with these dangerous toxins.

In freshwater systems, HAB toxins or

compounds cause taste and odour problems that impact

drinking and recreational waters. HAB events also result

in significant economic losses associated with reduced

tourism and restaurant business, regional fish or shell-

fish closures, aquaculture mortalities, increased cleanup

costs associated with dead fish and marine mammals or

unsightly accumulations and scum on the beaches. In

the US alone these losses are conservatively estimated

at USD82 million per year.

Need for early warning

Most of the human health impacts result either from

consumption of contaminated shellfish and drinking

water or from exposure to toxins during recreational

activities (e.g. beach-going, swimming, and boating).

Preventing or minimizing these impacts relies in the US

on extensive and costly monitoring programmes usually

conducted by state agencies. As soon as a HAB has been

detected, shellfish beds are closed to commercial or

recreational harvesting and warning signs are posted to

prevent use of beaches and recreational waters. Forecasts

and warnings allow state public health and resource

managers to better protect public health, reduce the

costs of monitoring, and minimize the economic impacts

of unnecessary closures.

Several kinds of forecasts are needed:

Nowcasts

– providing today’s HAB locations and

impacts, to better target sampling efforts

Forecasts

– giving the likely HAB locations and impacts

over the next few days, to allow time for managers to take

necessary actions in advance of the event

Long-term predictions

– anticipating when HABs are

likely to start, their potential severity, expected persis-

tence and timing of dissipation

Annual predictions

– assessing the likelihood of severe

HABs this year, using long-term data sets in conjunc-

tion with improved weather and hydrodynamic models.

Having these capabilities would allow strategic planning

weeks or months in advance by environmental