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The risk of brevetoxins to human health is further compounded by an increase in Karenia blooms. Center research has shown that average Karenia cell concentrations along the west coast of Florida have been increasing over the last 50 years, along with increases in the geographic extent and duration of the blooms [ 17 ]. Because K. The degree of human exposure to brevetoxin by this route depends upon a number of factors such as cell concentrations, wind speed and direction, and particle size of the aerosols [ 99 ]. Inhalation of aerosolized brevetoxins can lead to eye and respiratory irritation, bronchoconstriction, and a decrease in pulmonary function [ 18 , 99 ].

People affected begin coughing and sneezing, and develop runny noses, watery eyes, irritation in the throat, and have trouble breathing. Humans with asthma are particularly sensitive. A collaborative research project supported by NIEHS and other agencies, and involving Center scientists, has examined the human health consequences of exposure to brevetoxin aerosols. Emergency room admissions for pneumonia, bronchitis, asthma, and other respiratory problems were found to increase substantially during Karenia bloom events [ ].

While no deaths as a result of brevetoxin alone have ever been recorded [ 24 ], the possibility that brevetoxins or their effects could work in synergy with other preexisting health problems to increase death probabilities cannot be discounted. Center researchers are also examining the effects of sub-acute domoic acid DA exposure on gene expression in the vertebrate central nervous system using the zebrafish model system.

Zebrafish are currently recognized as one of the most important vertebrate model organisms for gene function and toxicogenomics studies [ ]. In addition, the zebrafish genome has been sequenced and large-scale genetic screens have been performed and extensively analyzed [ ].

Zebrafish mutations phenocopy many human disorders and results from these studies provide candidate genes and pathways for evaluation of disease in higher organisms. In terms of human health, there are growing concerns regarding toxicity due to chronic DA exposure particularly in Washington coastal Tribal communities that subsistence fish on razor clams, which are known to retain DA for up to a year [ 32 ].

Algal bloom - Wikipedia

The Quinault phrase ta'a Wshi xa'iits'os means "clam hungry," and illustrates the strong cultural reliance on razor clams for food. Schumacker, Quinault tribe, pers. A joint pilot project between two Centers used a zebrafish microarray to identify a subset of genes that were differentially expressed in the vertebrate central nervous system in response to low level asymptomatic DA exposure.

Connecting these genes identified in the zebrafish vertebrate model with the physiological processes they regulate will facilitate a more detailed understanding of the human health impacts of low-level chronic exposure to DA. The primary route of human exposure to microcystins in the Great Lakes is thought to be through drinking water and recreation.

Ecology of Harmful Algae

Another potential exposure route is through fish consumption due to the recreational and commercial importance of fishing in both regions of the Great Lakes and in inland lakes that have significant cyanobacterial HAB concentrations. Center scientists, in collaboration with university partners, have measured microcystin accumulation in the tissues of edible size fish caught in lakes with high cellular microcystin levels.

Concentrations of microcystin in the liver would be hazardous to human health, but quantities were significantly lower in muscle tissue [ ]. While most populations do not consume fish livers, this route of exposure needs to continue to be evaluated along with increased incidence of cyanobacterial blooms in the recreational and drinking waters, all of which could pose a significant concern for public health in the Great Lakes.

It is sometimes easy to lose sight of the risks that HABs pose to human health, because effective monitoring efforts prevent almost all shellfish poisoning events. The value of HAB research and monitoring is enormous in terms of risk avoidance and mitigation, but it makes epidemiological study of these phenomena extremely difficult.

Almost nothing is known about the effects of toxins below these regulatory limits, yet regular consumption of drinking water and seafood may result in chronic low-level toxin exposure. This risk can be particularly pronounced in certain sub-populations, for instance the elderly, or those whose diets rely heavily on seafoods for cultural or subsistence reasons. The risks of low-level toxin exposure during development, either in utero or during early childhood, are also unknown. Our understanding of the health risks of HAB toxins, and therefore our ability to mitigate those risks, is incomplete until we know the human health effects associated with both chronic and acute toxin exposures.

As mentioned above, one of the common goals of all of the OHH Centers is the development of predictive models that will help us to understand and avoid human health risks from HABs.


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Dyble et al. Center research generated two of three years of environmental monitoring data on in situ temperature, salinity, DIN, phosphate, and light that were incorporated into a series of regression equations to simulate seasonal patterns in these variables for the leeward and windward sides of the island of Hawaii.

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Cultured isolates were used to determine the physiological response curves of Hawaiian Gambierdiscus to different temperatures, nutrient concentrations, light, and salinities. These response curves were coupled with the seasonal patterns of the environmental variables in a Gambierdiscus population dynamics model. The model results were then compared to actual Gambierdiscus abundance data collected over the three year period at leeward and windward sites on the island of Hawaii to assess its accuracy and realism; preliminary results are shown in Figure 3.

In future modeling efforts, the environmental parameters will be subjected to randomized fluctuations within measured variability to study the various conditions that can cause a "bloom" of Gambierdiscus and a possible, subsequent outbreak of CFP. Preliminary results of a model simulating Gambierdiscus cell abundance per cm 3 of substrate versus actual Gambierdiscus abundance monthly-averaged over a three-year period for the leeward side of the island of Hawaii over a one-year period Julian Days.

Center researchers have also previously developed a coupled three-dimensional physical-biological model to understand, predict, and analyze Alexandrium blooms in the northeastern U. Alexandrium has a complex life cycle, which includes a resting "cyst" stage that forms at the end of a bloom, and enables the cells to remain dormant until the next spring bloom season begins.

The model includes germination of these cysts to begin the bloom, along with the speeds and directions of ocean currents, water temperature, salinity, winds, solar radiation, tides, river runoff, and nutrients to generate a simulation of an Alexandrium bloom.

Centers for Oceans and Human Health: a unified approach to the challenge of harmful algal blooms

Prior simulations have demonstrated that model predictions are quite similar to the actual bloom conditions observed in the field [ 77 ]. The model results also indicate that the behavior of the cells, the prevailing wind direction, and the input of fresh water from coastal rivers all play an important role in whether a bloom forms in a given year. Building upon their prior work, Center scientists used the model to perform "hindcast" simulations of a massive Alexandrium bloom in [ 6 ] to try to determine which factors were responsible for that unprecedented bloom. Three hypotheses were proposed: high resting cyst abundance, heavy rainfall and runoff, and major storm events "northeasters" that pushed surface waters and cells to the shore and along the coast.

Model conditions were systematically varied to produce the hindcast model simulations of the bloom; results indicate that high abundance of cysts in western GOM was the main cause of the bloom, although wind forcing was an important regulator. This suggests that monitoring of the regional abundance of cysts may hold the key to interannual forecasts of A. The combination of predictive modeling and the ability to perform hindcast simulations has tremendous power to help us understand the factors that are responsible for Alexandrium blooms, and represents a major advancement in HAB management.

In Florida, Center research has contributed to a notification system that uses a combination of remote sensing and ground-based monitoring to provide an early warning of K. The west coast of Florida is commonly affected by K. Florida government agencies routinely monitor the abundance of K. Because of the cost of widespread monitoring, remote sensing is used to target the water sampling.

High concentrations of chlorophyll detected by remote sensing are used as potential indicators of K. Targeted water sampling is then used to confirm the satellite data. Once elevated concentrations of K. Only the west coast is routinely monitored, since other areas are affected so infrequently that monitoring would not be cost effective. Remote sensing however, can track large blooms and monitor any long distance transport of them.

For areas not usually hit by K.

Thus, monitoring coupled with remote sensing allows for a more effective use of resources. Scientists use the satellite data, along with cell counts, meteorological data and oceanographic buoys to monitor bloom movement, for the purpose of predicting future developments.

This information is distributed to researchers and other interested partners weekly.

Information about K. Many tourist hotels along the beach also voluntarily provide such information, as tourists are much less aware of Florida's red tide than the local residents. Daily updates on the location of blooms are often posted on beaches, as well as websites, newspapers and radio stations, as K. A toll-free hotline is available for people to report any effects they have felt or to ask questions about Florida's red tide.

In the future, poison information center and other human health surveillance data as well as real-time monitoring by lifeguards on beaches will be incorporated into the system [ ]. The situations in Florida and the northeastern U. One reason for this is the lack of long-term observations and detailed laboratory studies to provide the data to parameterize and constrain the models. Development of the Alexandrium model benefited enormously from years of accumulated experimental data on the physiology of the dinoflagellate. This provided information on the behavior of the cysts and cells in response to light, nutrients, and temperature.

Numerous research cruises collected data on cell numbers and oceanographic conditions, during bloom and non-bloom years, and on the distribution and abundance of resting cysts in the sediments. All of this information was then coupled with an existing physical model of the region. For many organisms, these basic building blocks for a model are just not available.

This underscores the need for long-term observational field programs, and for basic physiological data on the organisms themselves. Our ability to understand and eventually predict HABs depends critically on this type of science. The establishment of the OHH Centers has greatly facilitated cooperation between researchers from different scientific disciplines and geographic regions. While Center research addresses the current challenges that HABs present, Center scientists are also cognizant of new, potentially unknown, problems in the future.

Two areas that are likely to become more prominent in the near future are emerging HAB species and events, and the effects of global environmental change on HABs see Moore et al. Paul Cox Institute for Ethno Medicine and colleagues. In Guam, human exposure to high quantities of BMAA results from unique components of the traditional Chamorro diet including cycad tortillas, flying foxes, and possibly other feral animals.

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The ubiquity of cyanobacteria in diverse terrestrial and aquatic environments suggests that ingestion of BMAA may occur through even less esoteric routes, including direct consumption of cyanobacteria or cyanobacterial hosts, bioaccumulation in additional food chains, or exposure to cyanobacteria-contaminated water supplies. Collaboration between two Centers is continuing this line of research by screening a variety of marine and freshwater ecosystems for evidence of BMAA biomagnification and potential human risk.

Structural similarities between the neurotransmitter L-glutamate and the neurotoxic carbamate adduct of BMAA. In addition to previously unknown HAB organisms or toxins, an additional threat comes from the expansion or emergence of known HABs in areas where they have not previously occurred. In the Gulf, oil platforms serve as colonization sites for G. The Gulf of Mexico has over of these producing sites, which provide a nexus for fisherman and potentially toxic fish.

Multiple CFP cases have been reported from fish caught near oil platforms [ ]. The steel archipelago of the northern and western Gulf of Mexico is a great experiment in providing refuges for tropical benthic species. This information is relevant to the advancement of diagnostic capabilities for ciguatera fish poisoning worldwide.