The Beach Manager’s Manual HARMFUL ALGAL BLOOMS WHAT ARE HABs? Harmful algal blooms, commonly referred to as HABs, are an environmentally complex problem throughout the world. When algae grows rapidly in a confined area, grows to the point where a microscope is not needed to see it, or when it grows rapidly to form a dense population, it is referred to as an algal bloom. Blooms can be found within most growth; however, they are bacteria. bodies of water throughout the High nutrient levels, warm water Great Lakes. They thrive in shallow, temperatures and high light levels warm, non-moving bodies of water — or a combination of all three like bays, smaller lakes and ponds. A factors — may stimulate the rapid HAB, is a bloom of blue-green algae reproduction of cyanobacteria that contains toxins. HABs can cause until it dominates the local aquatic fish kills, foul up nearby coastlines ecosystem, forming an algae bloom. and produce conditions that pose health risks to aquatic life, as well as Cyanobacteria can survive in many humans. aquatic environments ranging from deep-sea vents in the Atlantic Ocean to the pond in your local park. Cyanobacterial blooms vary in appearance and can appear as foam, scum, or mats on the surface of freshwater lakes and ponds. These blooms may manifest in a variety of colors, including blue- green, bright green, brown, or red.1 Visual observation of a water body alone will not confirm the presence of cyanobacteria, nor can it confirm Figure 1. Harmful algal bloom formation in the the presence of toxins in the water. nearshore region. (Photo: D. Straw) Examination of a water sample and identification with a microscope ABOUT CYANOBACTERIA will confirm the presence of cyanobacteria. Further analysis is Blue-green algae are also referred to necessary to determine toxicity. as cyanobacteria. These organisms have been around for thousands of HOW AN ALGAL years and are naturally occurring. BLOOM FORMS It is very important to note that not all algae produce toxins; those that Blooms form when a specific type don’t are not considered harmful. of algae increases until it dominates the aquatic system (Figure 1). Cyanobacteria act like algae in The formation of a bloom is also that they photosynthesize and influenced by the physical and utilize light and nutrients, such biological characteristics of the as phosphorous and nitrogen, for water, as well as the season. 2 The Beach Manager’s Manual A B C D E Figure 2. (a) Microcystis sp.; (b) Anabaena flos-aquae; (c) Anabaena circinalis; (d) Aphanizomenon flos-aquae, and (e) Cylindrospermopsis raciborskii. The conditions that contribute to toxins and often there is more than bloom formation include: one toxin present. The presence n The presence of nutrients such as of more than one toxin is due to nitrogen and phosphorus. multiple algal species present in the water sample.2 n Water temperatures between 15° and 30°C. There are more than 40 freshwater n pH levels between 6 and 9. species of toxic cyanobacteria. n Late summer or early fall. The most common species of cyanobacteria in the Great Lakes While heavy rainstorms and high that can produce toxins are: water flows increase runoff and n Microcystis aeruginosa increase nutrients in the water, n the increased turbulence is not Anabaena circinalis favorable for the formation of a n Anabaena flos-aquae cyanobacterial bloom. The initial n Aphanizomenon flos-aquae impact of a rainstorm or other n Cylindrospermopsis raciborskii turbulence displaces the cells in the water column before they can The three main classes of toxins become a bloom. produced by these cyanobacterial species are: TOXINS IN ALGAE 1) Nerve toxins, also called As stated previously, cyanobacterial neurotoxins blooms may be the cause of a wide 2) Liver toxins called hepatotoxins range of problems for recreational 3) Skin toxins called dermatotoxins users and animals living in the aquatic environment because The dermatotoxins cause they produce toxins. People may itching, rashes, and other allergic come into contact with toxins by reactions. All cyanobacteria are ingesting contaminated waters or dermatotoxins (i.e., produce skin through recreation. Overall, 50-75 irritants). Also, all of these toxins percent of bloom strains produce may cause gastrointestinal distress. HARMFUL ALGAL BLOOMS 3 Human Cell Concentration Chlorophyll a Table 1. World Health Health Risk (per milliliter) Concentration Organization (2003) provisional guidelines for threats to human health Low < 20,000 cells 1-10 ppb from recreational contact Moderate 20,000-100,000 cells 10-50 ppb with cyanobacteria4. High > 100,000 cells Visible scums EFFECTS OF TOXINS The effects of these toxins vary widely among individuals. They are dependent on age, health and the sensitivity of the individual to the toxin. The World Health Organization (WHO) has put forth recommended guidelines for algal toxin exposure for humans, which translate into 1µg/L for drinking water and 20 µg/L for recreational water contact (Table 1).3 A dead fish resulting from toxins. (Photo: Jennifer Graham, USGS) The WHO developed provisional guidelines to identify concentrations IMPACTS ON ANIMALS of Microcystis sp. and the toxin Fish that are impacted by microcystin that may impact human cyanobacteria may develop skin health. Potential risk to human lesions, making them vulnerable health from recreational contact to infection and disease. Toxic is considered low at microcystin blooms may also impact gill concentrations up to 4 ppb and functioning. Gas exchange across moderate at 20 ppb. the gill surface is reduced by mucous over the gills.5 SYMPTOMS OF HABs Some dog and livestock deaths EXPOSURE have been attributed to the HUMANS: numbness of lips, tingling ingestion of toxic water. in fingers and toes, dizziness, headache, rash or skin irritation, abdominal pain, diarrhea, The extent to which and vomiting. cyanobacterial toxins move up the PETS: weakness, staggering, convulsions, food chain (e.g., through zebra difficulty in breathing, and vomiting. mussels and fish) is currently being researched in the Great Lakes. 4 The Beach Manager’s Manual IMPACTS ON HUMANS it may cause worse repercussions Humans who come into contact for human and animal health with a HAB will likely experience than simply waiting for the HAB mild skin irritation or a rash. to dissipate. Some cyanobacterial blooms of Some beaches post warning signs Microcystis, Anabaena, and others to alert the public of possible have been linked to incidences of cyanobacteria in the water. human illness in the United States However, because HABs are as well as other countries. not regulated or monitored for Reported instances of health toxins, the majority of beaches impacts associated with algal toxin in the Great Lakes do not post exposure are limited in the public warning signs for HABs. health community. This is due to the lack of reporting by recreational users who become ill after contact with the algal toxin, the lack of knowledge of symptoms associated with HAB exposure, as well as the lack of training from medical professionals on symptoms and diagnoses. Symptoms of algal toxin exposure can be similar to those of the common cold, flu, and food poisoning, which could contribute to the lack of reporting or to misdiagnosis. Because of possible health hazards, Grand Lake St. Marys Water Quality Advisory experts highly recommend that Sign, 2009. (Photo: Linda Merchant-Masonbrink, people avoid skin contact with Ohio EPA) water that has visible blooms — whether they are known to be harmful or not. In addition, water bodies that are treated with algaecides, may release algal toxins during cyanobacterial die offs, even if no cyanobacteria is visible in the water. It is not recommended that HABs be treated in this manner as HARMFUL ALGAL BLOOMS 5 Tom Archer Minnesota Pollution Control Agency CLIMATE CHANGE Algal seasonal successions in AND HABs aquatic environments are changing, It is generally accepted that the with cyanobacteria showing frequency, intensity, and duration of up earlier and staying longer HABs in all aquatic environments throughout the seasons. If bloom- are increasing globally,6 & 7 which forming species become prevalent, may be, in part, due to climate the result will likely be increased change. However, the link between production of toxins that will have climate change and HABs is poorly adverse impacts on drinking water understood due to limited research.8 treatment and public health. Scientists anticipate, however, that Bloom-forming species are climate change will produce new associated with toxin production, extremes in climatic conditions. taste and odor compounds, This may lead to warmer surface and chemical byproducts after water temperatures, increased wastewater treatment. Therefore, nutrient (carbon, nitrogen, and as blooms become more frequent, phosphorous) loadings, altered there will be need for increased hydrology (more frequent floods water monitoring plus increased and droughts), changes in thermal treatment at water treatment plants. stratification (temperature or This all adds up to increased costs. density layers in the water), changes For more information on climate in the duration of ice cover, and change and HABs, see the other environmental alterations, American Association for the which will have a significant Advancement of Science annual impact on algal ecology. Growth meeting synopsis concerning rates, different species present in climate change.9 the water, and frequencies of algal blooms will likely be impacted. 6 The Beach Manager’s Manual FACTORS INFLUENCING THE GROWTH OF HARMFUL ALGAL BLOOMS Illustration: Michigan Sea Grant HOW CAN I KEEP HOW CAN WE MY BEACHGOING PREVENT HABs? PUBLIC SAFE? Beach managers and other community members can If there are visible layers of algae, the water is encourage their neighbors to follow a few steps to green or discolored, or a HAB warning has been reduce the development of HABs. posted, it is best to have beach visitors avoid n Reduce or eliminate the use of fertilizers.